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A model on the effects of leader, media, viruses, and worms and other agents on the opinion of individuals is developed and utilized to simulate the formation of consensus in society and price in market via excess between supply and demand. Effects of some time varying drives, (harmonic and hyperbolic) are also investigated. Key words: Opinion; Leader; Media; Market; Buyers; Sellers; Excess
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arxiv:physics/0607264
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Many proteins interact with and deform double-stranded DNA in cells. Single-molecule experiments have studied the elasticity of DNA with helix-deforming proteins, including proteins that bend DNA. These experiments increase the need for theories of DNA elasticity which include helix-deforming proteins. Previous theoretical work on bent DNA has examined a long DNA molecule with many nonspecifically binding proteins. However, recent experiments used relatively short DNA molecules with a single, well-defined bend site. Here we develop a simple theoretical description of the effect of a single bend. We then include the description of the bend in the finite worm like chain model (FWLC) of short DNA molecules attached to beads. We predict how the DNA force-extension relation changes due to formation of a single permanent kink, at all values of the applied stretching force. Our predictions show that high-resolution single-molecule experiments could determine the bend angle induced upon protein binding.
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arxiv:physics/0607267
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Deviations from the average can provide valuable insights about the organization of natural systems. This article extends this important principle to the more systematic identification and analysis of singular local connectivity patterns in complex networks. Four measurements quantifying different and complementary features of the connectivity around each node are calculated and multivariate statistical methods are then applied in order to identify outliers. The potential of the presented concepts and methodology is illustrated with respect to a word association network.
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arxiv:physics/0607272
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We use a replica approach to deal with portfolio optimization problems. A given risk measure is minimized using empirical estimates of asset values correlations. We study the phase transition which happens when the time series is too short with respect to the size of the portfolio. We also study the noise sensitivity of portfolio allocation when this transition is approached. We consider explicitely the cases where the absolute deviation and the conditional value-at-risk are chosen as a risk measure. We show how the replica method can study a wide range of risk measures, and deal with various types of time series correlations, including realistic ones with volatility clustering.
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arxiv:physics/0608035
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We demonstrate area-enclosing atom interferometry based on a moving guide. Light pulses along the free propagation direction of a magnetic guide are applied to split and recombine the confined atomic matter-wave, while the atoms are translated back and forth along a second direction in 50 ms. The interferometer is estimated to resolve ten times the earth rotation rate per interferometry cycle. We demonstrate a ``folded figure 8'' interfering configuration for creating a compact, large-area atom gyroscope with multiple-turn interfering paths.
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arxiv:physics/0608083
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The goal of the EUDET project is the development and construction of infrastructure to permit detector R&D for the International Linear Collider (ILC) with larger scale prototypes. It encompasses major detector components: the vertex detector, the tracker and the calorimeters. We describe here the status and plans of the project with emphasis on issues related to data acquisition for future test beam experiments.
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arxiv:physics/0608090
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We observed new effect which we called photonic flame effect (PFE). Several 3-dimensional photonic crystals (artificial opals) were posed on Cu plate at the temperature of liquid nitrogen (77K). Typical distance between them was 1-5 centimeters. Long-continued optical luminescence was excited in one of them by the ruby laser pulse. Analogous visible luminescence manifesting time delay appeared in other samples of the crystals. Experiments were realized for opal crystals and for nanocomposites (opals filled with nonlinear liquids).
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arxiv:physics/0608150
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The STAR experiment at the Relativistic Heavy Ion Collider RHIC studies the new state of matter produced in relativistic heavy ion collisions and the spin structure of the nucleon in collisions of polarized protons. In order to improve the capabilities for heavy flavor measurements and the reconstruction of charged vector bosons an upgrade of the tracking system both in the central and the forward region is pursued. The integrated system providing high resolution tracking and secondary vertex reconstruction capabilities will use silicon pixel, strip and GEM technology.
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arxiv:physics/0608199
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We will focus on the Quantum theory and starting from simple philosophical conjectures, we infer possible different physical realities. Also we argue of possible wavefunction emerging under specific conditions of the physical reality. Finally, we affirm that the "hidden choice" of the ontic elements as primitive is a fundamental step to analyze the construction of any theory.
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arxiv:physics/0608208
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Portfolio theory is a very powerful tool in the modern investment theory. It is helpful in estimating risk of an investor's portfolio, which arises from our lack of information, uncertainty and incomplete knowledge of reality, which forbids a perfect prediction of future price changes. Despite of many advantages this tool is not known and is not widely used among investors on Warsaw Stock Exchange. The main reason for abandoning this method is a high level of complexity and immense calculations. The aim of this paper is to introduce an automatic decision - making system, which allows a single investor to use such complex methods of Modern Portfolio Theory (MPT). The key tool in MPT is an analysis of an empirical covariance matrix. This matrix, obtained from historical data is biased by such a high amount of statistical uncertainty, that it can be seen as random. By bringing into practice the ideas of Random Matrix Theory (RMT), the noise is removed or significantly reduced, so the future risk and return are better estimated and controlled. This concepts are applied to the Warsaw Stock Exchange Simulator http://gra.onet.pl. The result of the simulation is 18 % level of gains in comparison for respective 10 % loss of the Warsaw Stock Exchange main index WIG.
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arxiv:physics/0608293
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The eigenmode spectrum is a fundamental starting point for the analysis of plasma stability and the onset of turbulence, but the characterization of the spectrum even for the simplest plasma model, ideal magnetohydrodynamics (MHD), is not fully understood. This is especially true in configurations with no continuous geometric symmetry, such as a real tokamak when the discrete nature of the external magnetic field coils is taken into account, or the alternative fusion concept, the stellarator, where axisymmetry is deliberately broken to provide a nonzero winding number (rotational transform) on each invariant torus of the magnetic field line dynamics (assumed for present purposes to be an integrable Hamiltonian system). Quantum (wave) chaos theory provides tools for characterizing the spectrum statistically, from the regular spectrum of the separable case (integrable semiclassical dynamics) to that where the semiclassical ray dynamics is so chaotic that no simple classification of the individual eigenvalues is possible (quantum chaos). The MHD spectrum exhibits certain nongeneric properties, which we show, using a toy model, to be understable from the number-theoretic properties of the asymptotic spectrum in the limit of large toroidal and poloidal mode (quantum) numbers when only a single radial mode number is retained. Much more realistically, using the ideal MHD code CAS3D, we have constructed a data set of several hundred growth-rate eigenvalues for an interchange-unstable three-dimensional stellarator equilibrium with a rather flat, nonmonotonic rotational transform profile. Statistical analysis of eigenvalue spacings shows evidence of generic quantum chaos, which we attribute to the mixing effect of having a large number of radial mode numbers.
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arxiv:physics/0608304
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The Hurst exponent $H$ of long range correlated series can be estimated by means of the Detrending Moving Average (DMA) method. A computational tool defined within the algorithm is the generalized variance $ \sigma_{DMA}^2={1}/{(N-n)}\sum_i [y(i)-\widetilde{y}_n(i)]^2\:$, with $\widetilde{y}_n(i)= {1}/{n}\sum_{k}y(i-k)$ the moving average, $n$ the moving average window and $N$ the dimension of the stochastic series $y(i)$. This ability relies on the property of $\sigma_{DMA}^2$ to scale as $n^{2H}$. Here, we analytically show that $\sigma_{DMA}^2$ is equivalent to $C_H n^{2H}$ for $n\gg 1$ and provide an explicit expression for $C_H$.
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arxiv:physics/0608313
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The effectiveness of carbon supported polyaniline as anode catalyst in a fuel cell (FC) with direct formic acid electrooxidation is experimentally demonstrated. A prototype FC with such a platinum-free composite anode exhibited a maximum room-temperature specific power of about 5 mW/cm2
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arxiv:physics/0609025
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We describe the setup to create a large Bose-Einstein condensate containing more than 120x10^6 atoms. In the experiment a thermal beam is slowed by a Zeeman slower and captured in a dark-spot magneto-optical trap (MOT). A typical dark-spot MOT in our experiments contains 2.0x10^10 atoms with a temperature of 320 microK and a density of about 1.0x10^11 atoms/cm^3. The sample is spin polarized in a high magnetic field, before the atoms are loaded in the magnetic trap. Spin polarizing in a high magnetic field results in an increase in the transfer efficiency by a factor of 2 compared to experiments without spin polarizing. In the magnetic trap the cloud is cooled to degeneracy in 50 s by evaporative cooling. To suppress the 3-body losses at the end of the evaporation the magnetic trap is decompressed in the axial direction.
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arxiv:physics/0609028
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The paper explores a possible application of the discrete thermodynamics to a 2-level laser. The model accounts for the laser openness to incoming pumping power and coming out energy with the emitted light. As an open system, a laser should be in open equilibrium with thermodynamic forces, related to both energy flows. Conditions of equilibria are expressed by a logistic map with specially developed dynamic inverse pitchfork bifurcation diagrams for graphical presentation of the solutions. The graphs explicitly confirm the triggering nature of a laser where bistability is manifested by pitchfork ground and laser branches, with the relative population equilibrium values close to 1 and 0 correspondingly. Simulation was run for a 2-level laser emitting light from far infrared to short wave UV. A newly discovered feature of such a laser is the line spectrum of up and down transitions of the laser excitable dwellers, occurring between the laser and the ground pitchfork branches beyond bifurcation point. The density of the spectra lines tangibly increases as the branches approach their limits. Transitions of both types are overlapping in opposite phases. This effect is a new confirmation of the Einstein's prohibition on practical realization of a 2-level laser. Wide enough gaps between the lines of the spectra were also discovered in this research. The gaps are shielding the light irradiation and may be considered as potential areas of control over the 2-level laser emissions.
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arxiv:physics/0609044
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"Conventional" scenario of metastable melting in ordinary substances in the limit of zero temperature assumes that the melting curve reaches the matter zero isotherm ("cold curve"). The same is true for standard variant of one-component plasma model on rigid compensating background in both limits: classical and "cold" quantum melting. The modified OCP on uniform, but compressible background shows the completely different scenario of the metastable melting closure. The remarkable feature of this scenario is that the liquid freezing curve terminates at liquid spinodal curve of 1st-order liquid gas phase transition, which takes place in this type of OCP models ("spinodal decomposition").
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arxiv:physics/0609059
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Electron cooling that results when a bunch of electrons overlaps a bunch of ions , with both bunches moving at the same velocity, may be considered to be an intrabeam scattering process. The process is similar to the usual intrabeam scattering, where the ions scatter from each other and usually results in beam growth. An important difference is that in electron cooling the mass of the ion is different from and much larger than the mass of the electron. This difference considerably complicates the intrabeam scattering theory. It introduces a new term in the emittance growth rate, which vanishes when the particles are identical and their masses are equal, and can give rise to emittance cooling of the heavier particles . The term that gives rise to beam growth for the usual intrabeam scattering is also present but is much smaller than the cooling term when one particle is much heavier than the other. This paper derives the results found for the emittance cooling rates due to the scattering of the ions in the ion bunch by the electons in the electron bunch.
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arxiv:physics/0609076
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The importance of finite-size effects for the electronic structure of long zigzag and armchair carbon nanotubes is studied. We analyze the electronic structure of capped (6,6), (8,0), and (9,0) single walled carbon nanotubes as a function of their length up to 60 nm, using a divide and conquer density functional theory approach. For the metallic nanotubes studied, most of the physical features appearing in the density of states of an infinite carbon nanotube are recovered at a length of 40 nm. The (8,0) semi-conducting nanotube studied exhibits pronounced edge effects within the energy gap that scale as the inverse of the length of the nanotube. As a result, the energy gap reduces from the value of ~1 eV calculated for the periodic system to a value of ~0.25 eV calculated for a capped 62 nm long CNT. These edge effects are expected to become negligible only at tube lengths exceeding 6 micrometers. Our results indicate that careful tailoring of the nature of the system and its capping units should be applied when designing new nanoelectronic devices based on carbon nanotubes. These conclusions are expected to hold for other one-dimensional systems such as graphene nanoribbons, conducting polymers, and DNA molecules.
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arxiv:physics/0609091
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The linear instability and nonlinear dynamics of collisional (resistive) and collisionless (due to electron inertia) double tearing modes (DTMs) are compared with the use of a reduced cylindrical model of a tokamak plasma. We focus on cases where two q = 2 resonant surfaces are located a small distance apart. It is found that regardless of the magnetic reconnection mechanism, resistivity or electron inertia, the fastest growing linear eigenmodes may have high poloidal mode numbers m ~ 10. The spectrum of unstable modes tends to be broader in the collisionless case. In the nonlinear regime, it is shown that in both cases fast growing high-m DTMs lead to an annular collapse involving small magnetic island structures. In addition, collisionless DTMs exhibit multiple reconnection cycles due to reversibility of collisionless reconnection and strong ExB flows. Collisionless reconnection leads to a saturated stable state, while in the collisional case resistive decay keeps the system weakly dynamic by driving it back towards the unstable equilibrium maintained by a source term.
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arxiv:physics/0609115
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We demonstrate the detection of magnetic particles carried by water in a continuous flow using an atomic magnetic gradiometer. Studies on three types of magnetic particles are presented: a single cobalt particle (diameter ~150 um, multi-domain), a suspension of superparamagnetic magnetite particles (diameter \~1 um), and ferromagnetic cobalt nanoparticles (diameter ~10 nm, 120 kA/m magnetization). Estimated detection limits are 20 um diameter for a single cobalt particle at a water flow rate 30 ml/min, 5x10^3 magnetite particles at 160 ml/min, and 50 pl for the specific ferromagnetic fluid at 130 ml/min. Possible applications of our method are discussed.
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arxiv:physics/0609197
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The studies of crystal collimation in the experiments at Relativistic Heavy Ion Collider and Tevatron and in computer simulations reveal strong coherent effects observed in a very broad angular range. Our theory explains the effects by coherent scattering on the potential of bent crystal atomic planes, which amplifies beam diffusion in accelerator by orders of magnitude. This coherent scattering in bent crystal is being studied in a CERN SPS experiment. We present Monte Carlo predictions for the SPS and Tevatron experiments, and show the implications of the coherent scattering effect for crystal collimation in the Large Hadron Collider.
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arxiv:physics/0609214
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A hydrodynamic model for determining the electrophoretic speed of a polyelectrolyte through a nanopore is presented. It is assumed that the speed is determined by a balance of electrical and viscous forces arising from within the pore and that classical continuum electrostatics and hydrodynamics may be considered applicable. An explicit formula for the translocation speed as a function of the pore geometry and other physical parameters is obtained and is shown to be consistent with experimental measurements on DNA translocation through nanopores in silicon membranes. Experiments also show a weak dependence of the translocation speed on polymer length that is not accounted for by the present model. It is hypothesized that this is due to secondary effects that are neglected here.
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arxiv:physics/0609244
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We calculate bisoliton solutions using a slowly varying stroboscopic equation. The system is characterized in terms of a single dimensionless parameter. We find two branches of solutions and describe the structure of the tails for the lower branch solutions.
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arxiv:physics/0609246
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We present a new kind of generator of internal waves which has been designed for three purposes. First, the oscillating boundary conditions force the fluid particles to travel in the preferred direction of the wave ray, hence reducing the mixing due to forcing. Secondly, only one ray tube is produced so that all of the energy is in the beam of interest. Thirdly, temporal and spatial frequency studies emphasize the high quality for temporal and spatial monochromaticity of the emitted beam. The greatest strength of this technique is therefore the ability to produce a large monochromatic and unidirectional beam.
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arxiv:physics/0609256
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In this paper we introduce a hands-on activity in which introductory astronomy students act as gravitational wave astronomers by extracting information from simulated gravitational wave signals. The process mimics the way true gravitational wave analysis will be handled by using plots of a pure gravitational wave signal. The students directly measure the properties of the simulated signal, and use these measurements to evaluate standard formulae for astrophysical source parameters. An exercise based on the discussion in this paper has been written and made publicly available online for use in introductory laboratory courses.
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arxiv:physics/0610028
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To investigate the finite time singularity in three-dimensional (3D) Euler flows, the simplified model of 3D axisymmetric incompressible fluids (i.e., two-dimensional Boussinesq approximation equations) is studied numerically. The system describes a cap-like hot zone of fluid rising from the bottom, while the edges of the cap lag behind, forming eye-like vortices. The hot liquid is driven by the buoyancy and meanwhile attracted by the vortices, which leads to the singularity-forming mechanism in our simulation. In the previous 2D Boussinesq simulations, the symmetricial initial data is used. However, it is observed that the adoption of symmetry leads to coordinate singularity. Moreover, as demonstrated in this work that the locations of peak values for the vorticity and the temperature gradient becomes far apart as $t$ approaches the predicted blow-up time. This suggests that the symmetry assumption may be unreasonable for searching solution blow-ups. One of the main contributions of this work is to propose an appropriate asymmetric initial condition, which avoids coordinate singularity and also makes the blow-up to occur much earlier than that given by the previously simulations. The shorter simulation time suppresses the development of the round-off error. On the numerical side, the pseudo-spectral method with filtering technique is adopted. The resolutions adopted in this study vary from $1024^2$, $2048^2$, $4096^2$ to $6144^2$. With our proposed asymmetric initial condition, it is shown that the $4096^2$ and $6144^2$ runs yield convergent results when $t$ is fairly close to the predicted blow-up time. Moreover, as expected the locations of peak values for the vorticity and the temperature gradient are very close to each other as $t$ approaches the predicted blow-up time.
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arxiv:physics/0610053
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It is shown that the contribution to the induction which at an internal point of a spin density distribution is mathematically described as a local is virtually caused by the summing-up of the fields created by all elements of this distribution. Therefore, the proportionality coefficient between this contact (Fermi) field and magnetic moment density at the point of observation is equal to 8pi/3 only for spherically symmetrical s-shells. If the symmetry of spin density distribution lowers, the value of this coefficient becomes dependent on the spin direction. As a sequence, in low-symmetry crystals and molecules additional anisotropic contributions to the hyperfine field emerge.
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arxiv:physics/0610060
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Large spherical scintillation detectors are playing an increasingly important role in experimental neutrino physics studies. From the instrumental point of view the primary signal response of these set-ups is constituted by the time and amplitude of the anode pulses delivered by each individual phototube following a particle interaction in the scintillator. In this work, under some approximate assumptions, we derive a number of analytical formulas able to give a fairly accurate description of the most important timing features of these detectors, intended to complement the more complete Monte Carlo studies normally used for a full modelling approach. The paper is completed with a mathematical description of the event position distributions which can be inferred, through some inference algorithm, starting from the primary time measures of the photomultiplier tubes.
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arxiv:physics/0610080
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Two approaches to studying the correlation functions of the binary Markov sequences are considered. The first of them is based on the study of probability of occurring different ''words'' in the sequence. The other one uses recurrence relations for correlation functions. These methods are applied for two important particular classes of the Markov chains. These classes include the Markov chains with permutative conditional probability functions and the additive Markov chains with the small memory functions. The exciting property of the self-similarity (discovered in Phys. Rev. Lett. 90, 110601 (2003) for the additive Markov chain with the step-wise memory function) is proved to be the intrinsic property of any permutative Markov chain. Applicability of the correlation functions of the additive Markov chains with the small memory functions to calculating the thermodynamic characteristics of the classical Ising spin chain with long-range interaction is discussed.
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arxiv:physics/0610081
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We consider one-dimensional classical time-dependent Hamiltonian systems with quasi-periodic orbits. It is well-known that such systems possess an adiabatic invariant which coincides with the action variable of the Hamiltonian formalism. We present a new proof of the adiabatic invariance of this quantity and illustrate our arguments by means of explicit calculations for the harmonic oscillator. The new proof makes essential use of the Hamiltonian formalism. The key step is the introduction of a slowly-varying quantity closely related to the action variable. This new quantity arises naturally within the Hamiltonian framework as follows: a canonical transformation is first performed to convert the system to action-angle coordinates; then the new quantity is constructed as an action integral (effectively a new action variable) using the new coordinates. The integration required for this construction provides, in a natural way, the averaging procedure introduced in other proofs, though here it is an average in phase space rather than over time.
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arxiv:physics/0610084
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The refractive index of single microparticles is derived from precise measurement and rigorous modeling of the stiffness of a laser trap. We demonstrate the method for particles of four different materials with diameters from 1.6 to 5.2 microns and achieve an accuracy of better than 1%. The method greatly contributes as a new characterization technique because it works best under conditions (small particle size, polydispersion) where other methods, such as absorption spectroscopy, start to fail. Particles need not be transferred to a particular fluid, which prevents particle degradation or alteration common in index matching techniques. Our results also show that advanced modeling of laser traps accurately reproduces experimental reality.
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arxiv:physics/0610087
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We consider complex-valued solutions of the three-dimensional Navier-Stokes system without external forcing on $R^3$. We show that there exists an open set in the space of 10-parameter families of initial conditions such that for each family from this set there are values of parameters for which the solution develops blow up in finite time.
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arxiv:physics/0610101
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We discuss the special challenges posed by measuring diffractive and forward physics at the LHC at high luminosity and the solutions proposed by the FP420 R&D collaboration.
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arxiv:physics/0610156
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Strong reciprocity is a fundamental human characteristic associated with our extraordinary sociality and cooperation. Laboratory experiments on social dilemma games and many field studies have quantified well-defined levels of cooperation and propensity to punish/reward. The level of cooperation is observed to be strongly dependent on the availability of punishments and/or rewards. Here, we suggest that the propensity for altruistic punishment and reward is an emergent property that has co-evolved with cooperation by providing an efficient feedback mechanism through both biological and cultural interactions. By favoring high survival probability and large individual gains, the propensity for altruistic punishment and rewards reconciles self- and group interests. We show that a simple cost/benefit analysis at the level of a single agent, who anticipates the action of her fellows, determines an optimal level of altruistic punishment, which explains quantitatively experimental results on the third-party punishment game, the ultimatum game and altruistic punishment games. We also report numerical simulations of an evolutionary agent-based model of repeated agent interactions with feedback-by-punishments, which confirms that the propensity to punish is a robust emergent property selected by the evolutionary rules of the model.
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arxiv:physics/0610225
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We perform an objective change-point analysis on 106 years of historical hurricane number data. The algorithm we use looks at all possible combinations of change-points and compares them in terms of the variances of the differences between real and modelled numbers. Overfitting is avoided by using cross-validation. We identify four change-points, and show that the presence of temporal structure in the hurricane number time series is highly statistically significant.
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arxiv:physics/0611071
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The Bruggeman formalism provides an estimate of the effective permittivity of a composite material comprising two constituent materials, with each constituent material being composed of electrically small particles. When one of the constituent materials is silver and the other is an insulating material, the Bruggeman estimate of the effective permittivity of the composite exhibits resonances with respect to volume fraction that are not physically plausible.
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arxiv:physics/0611087
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Radiation spectrum of extreme relativistic electrons and a probability of electron-positron pair production by energetic photons in a strong plasma wakefield are derived in the framework of a semiclassical approach. It is shown that that the radiation losses of the relativistic electron in the plasma wakefield scale as $ \propto \epsilon ^{2 / 3}$ in the quantum limit when the energy of the radiated photon becomes close to the electron energy, $\epsilon $. The quantum effects will play a key role in future plasma-based accelerators operating at ultrahigh energy of the electrons.
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arxiv:physics/0611094
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We present preliminary results of measurements of the quenching factor for Na recoils in NaI(Tl) at room temperature, made at a dedicated neutron facility at the University of Sheffield. Measurements have been performed with a 2.45 MeV mono-energetic neutron generator in the energy range from 10 keV to 100 keV nuclear recoil energy. A BC501A liquid scintillator detector was used to tag neutrons. Cuts on pulse-shape discrimination from the BC501A liquid scintillator detector and neutron time-of-flight were performed on pulses recorded by a digitizer with a 2 ns sampling time. Measured quenching factors range from 19% to 26%, in agreement with other experiments. From pulse-shape analysis, a mean time of pulses from electron and nuclear recoils are compared down to 2 keV electron equivalent energy.
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arxiv:physics/0611156
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We concentrate on several relatively new aspects of the study of fast electron scattering by atoms and atom-like objects, namely endohedral atoms and fullerenes. We show that the corresponding cross sections, being expressed via so-called Generalized Oscillator Strengths (GOS), give information on the electronic structure of the target and on the role of electron correlations in it. We consider what sort of information became available when analyzing the dependence of GOS upon their multipolarity, transferred momentum and energy. We demonstrate the role of nondipole corrections in the small-angle fast-electron inelastic scattering. There dipole contribution dominates while non-dipole corrections can be considerably and controllably enhanced as compared to the case of low and medium energy photoionization. We show also that analyses of GOS for discrete level excitations permit to clarify their multipolarity. The results of calculations of Compton excitation and ionization cross-sections for noble gas atoms are presented. Attention is given to cooperative effects in inelastic fast electron - atom scattering that results in directed motion of the secondary electrons, a phenomenon that is similar to drag currents in photoionization. We demonstrate how one should derive GOS for endohedral atoms, e.g. A@C60 and what is the additional information that can be obtained from corresponding GOS. Most of discussions are illustrated by the results of concrete calculations.
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arxiv:physics/0611218
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Rates for rotational excitation of HC3N by collisions with He atoms and H2 molecules are computed for kinetic temperatures in the range 5-20K and 5-100K, respectively. These rates are obtained from extensive quantum and quasi-classical calculations using new accurate potential energy surfaces (PES).
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arxiv:physics/0611258
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Recent progress in the spectroscopy of antiprotonic helium has allowed for measuring the separation between components of the hyperfine structure (HFS) of the (37,35) metastable states with an accuracy of 300 MHz, equivalent to a relative accuracy of 3x10^{-5}. The analysis of the uncertainties of the available theoretical results on the antiprotonic helium HFS shows that the accuracy of the value of the dipole magnetic moment of the antiproton (currently known to only 0.3 %) may be improved by up to 2 orders of magnitude by measuring the splitting of appropriately selected components of the HFS of any of the known metastable states. The feasibility of the proposed measurement by means of an analog of the triple resonance method is also discussed.
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arxiv:physics/0612021
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Codes were written to simulate the propagation of monochromatic light through a bare optical resonator, using a computational Fourier method to solve the Huygens-Fresnel integral. This was used, in the Fox-Li method, to find the lowest-loss eigenmodes of arbitrary cavity designs. An implicit shift `hopping' method was employed to allow a series of increasingly higher-loss eigenmodes to be found, limited in number by computational time. Codes were confirmed in their accuracy against the literature, and were used to investigate a number of different cavity configurations. In addition to confirming the fractal nature of eigenmodes imaged at the conjugate plane of a symmetric (g<-1) resonator, an initial study was made of how the (imperfect) quality of the fractal fit varied as the defining aperture was moved around the cavity. A comparison was also made with the fractal-patterns produced by codes written to simulate basic video-feedback.
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arxiv:physics/0612027
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The network approach plays a distinguished role in contemporary science of complex systems/phenomena. Such an approach has been introduced into seismology in a recent work [S. Abe and N. Suzuki, Europhys. Lett. 65, 581 (2004)]. Here, we discuss the dynamical property of the earthquake network constructed in California and report the discovery that the values of the clustering coefficient remain stationary before main shocks, suddenly jump up at the main shocks, and then slowly decay following a power law to become stationary again. Thus, the network approach is found to characterize main shocks in a peculiar manner.
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arxiv:physics/0612058
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We reminisce on the first steps of the cosmology community in Portugal, which can be traced back to about 20 years ago, and discuss its achievements and current specificities. We also reflect on the aspirations, hopes and challenges for the future.
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arxiv:physics/0612066
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Agents are represented by nodes on a random graph (e.g., small world or truncated power law). Each agent is endowed with a zero-mean random value that may be either positive or negative. All agents attempt to find relief, i.e., to reduce the magnitude of that initial value, to zero if possible, through exchanges. The exchange occurs only between agents that are linked, a constraint that turns out to dominate the results. The exchange process continues until a Pareto equilibrium is achieved. Only 40%-90% of the agents achieved relief on small world graphs with mean degree between 2 and 40. Even fewer agents achieved relief on scale-free like graphs with a truncated power law degree distribution. The rate at which relief grew with increasing degree was slow, only at most logarithmic for all of the graphs considered; viewed in reverse, relief is resilient to the removal of links.
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arxiv:physics/0612085
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The heart beat data recorded from samples before and during meditation are analyzed using two different scaling analysis methods. These analyses revealed that mediation severely affects the long range correlation of heart beat of a normal heart. Moreover, it is found that meditation induces periodic behavior in the heart beat. The complexity of the heart rate variability is quantified using multiscale entropy analysis and recurrence analysis. The complexity of the heart beat during mediation is found to be more.
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arxiv:physics/0612088
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Based on first principles solutions in a unified framework of quantum mechanics and electromagnetism we predict the presence of a universal attractive depolarisation radiation (DR) Lorentz force ($F$) between quantum entities, each being either an IED matter particle or light quantum, in a vacuuonic dielectric vacuum. Given two quantum entities $i=1,2$ of either kind, of characteristic frequencies $\nu_i^0$, masses $m_i^0=h\nu_i^0 / c^2$ and separated at a distance r^0, the solution is $F=- G m_1^0 m_2^0/ (r^0)^2$, where $G= \chi_0^2 e^4/12 \pi^2 \epsilon_0^2 \rho_\lambda$, $\chi_0$ is the susceptibility and $\rho_\lambda$ is the reduced linear mass density of the dielectric vacuum. This force $F$ is accurate at the weak $F$ limit and resembles in all respects Newton's gravity; hence $G$ is the gravitational constant. The DR wave fields and hence the gravity is propagated in the dielectric vacuum at the speed of light $c$; these can not be shielded by matter. A test particle $\mu$ of mass $m^0$ at $r^0$ apart from a large mass $M$ is therefore gravitated by all of the building particles of M directly, by a total gravitational potential $V = -G M m^0/ r^0$. For a finite $V$ and hence a total Hamiltonian $H= m^0 c^2 +V$, solution for the eigenvalue equation of $\mu$ presents a red-shift in the eigen frequency $\nu= \nu^0 (1- GM/r^0 c^2)$ and accordingly other wave variables. The quantum solutions combined with the wave nature of the gravity further lead to dilated gravito optical distance $r=r^0/(1- GM/r^0 c^2) $ and time $t=t^0/(1- GM/r^0 c^2) $, and modified Newton's gravity and Einstein's mass energy relation. Applications of these give predictions of the general relativistic effects manifested in the four classical test experiments of Einstein's general relativity (GR), in direct agreement with the experiments and the predictions given based on GR.
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arxiv:physics/0612096
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The TOTEM experiment will detect leading protons scattered in angles of microradians from the interaction point at the Large Hadron Collider. This will be achieved using detectors with a minimized dead area at the edge. The collaboration has developed an innovative structure at the detector edge reducing the conventional dead width to less than 100 microns, still using standard planar fabrication technology. In this new development, the current of the surface is decoupled from the sensitive volume current within a few tens of micrometers. The basic working principle is explained in this paper. Final size detectors have been produced using this approach. The current-voltage and current-temperature characteristics of the detectors were studied and the detectors were successfully tested in a coasting beam experiment.
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arxiv:physics/0612105
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As education systems move toward business models of operation, there is a strong tendency to misidentify the student as the customer. Misidentifying the student as the customer leads to interpretation of the course credit or degree as the product. The true product is the additional knowledge, skill, and ability that course credit and degree should represent. Consequences are potentially disastrous, because the notion that "the customer is always right" can lead to the perceived product (course credit or degree) meeting the desires of the misidentified "customer" (student) rather than the real product (value added to student) meeting the standards of the properly identified customers (future employers and taxpayers).
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arxiv:physics/0612117
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We describe how we can precisely measure variations in the entropy S of small solid samples below room temperature, as a function the temperature T or the external magnetic field H, respectively. A simple differential-thermal analysis (DTA) technique allows, in principle, for the measurement of variations in S without any instrumental broadening of the data. The method is particularly well suited for the detection of sharp phase transitions in samples of milligram size.
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arxiv:physics/0612130
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We prove with an exact relativistic computation that the spherosymmetric gravitational collapses with a time-dependent pressure end in bodies with a small, but finite volume. Against a diffuse, wrong conviction.
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arxiv:physics/0612160
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The interplay between magic number stabilities and superfluidity of small para-hydrogen clusters with sizes $N = 5$ to 40 and temperatures $0.5 K \leq T \leq 4.5 $K is explored with classical and quantum Path Integral Monte Carlo calculations. Clusters with $N < 26$ and T $\leq 1.5 K$ have large superfluid fractions even at the stable magic numbers 13, 19, and 23. In larger clusters, superfluidity is quenched especially at the magic numbers 23, 26, 29, 32, and 37 while below 1 K, superfluidity is recovered for the pairs $(27,28)$, $(30,31)$, and $(35,36)$. For all clusters superfluidity is localized at the surface and correlates with long exchange cycles involving loosely bound surface molecules.
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arxiv:physics/0612161
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A suite of numerical model-derived turbulence assessment products has recently been developed by NESDIS/STAR and implemented on the World Wide Web. The existing product suite is intended to provide turbulence information to aircraft flying in the vicinity of the jet stream. Turbulence is also a frequently occurring phenomenon in the boundary layer and may pose a threat to low-flying aircraft and aircraft during the take-off and landing phases of flight. Therefore, a numerical model-derived boundary layer turbulence product is under development. The boundary layer turbulence index (TIBL) product is designed to assess the potential for turbulence in the lower troposphere, generated using National Center for Environmental Prediction (NCEP) Rapid Update Cycle (RUC)-2 model data. The index algorithm approximates boundary layer turbulent kinetic energy (TKE) by parameterizing vertical wind shear, responsible for mechanical production, and kinematic heat flux, responsible for buoyant production. The TIBL product is expected to be most effective during the afternoon hours in a regime characterized by a quasi-steady state convective mixed layer. Preliminary case studies and validation have revealed a strong correlation between the presence of TKE maxima and peak wind gust magnitude observed at the surface in evolving morning or mature afternoon mixed layers.
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arxiv:physics/0612189
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The anisotropy of the speed of light at 1 part in 10^3 has been detected by Michelson and Morley (1887), Miller (1925/26), Illingworth (1927), Joos (1930), Jaseja et al. (1964), Torr and Kolen (1984), De Witte (1991) and Cahill (2006) using a variety of experimental techniques, from gas-mode Michelson interferometers (with the relativistic theory for these only determined in 2002) to one-way RF coaxial cable propagation timing. All agree on the speed, right ascension and declination of the anisotropy velocity. The Stephan Marinov experiment (1984) detected a light speed anisotropy using a mechanical coupled shutters technique which has holes in co-rotating disks, essentially a one-way version of the Fizeau mechanical round-trip speed-of-light experiment. The Marinov data is re-analysed herein because the velocity vector he determined is in a very different direction to that from the above experiments. No explanation for this difference has been uncovered.
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arxiv:physics/0612201
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Using a TE/TM decomposition for an angular plane-wave spectrum of free random electromagnetic waves and matched boundary conditions, we derive the probability density function for the energy density of the vector electric field in the presence of a semi-infinite isotropic medium. The theoretical analysis is illustrated with calculations and results for good electric conductors and for a lossless dielectric half-space. The influence of the permittivity and conductivity on the intensity, random polarization, statistical distribution and standard deviation of the field is investigated, both for incident plus reflected fields and for refracted fields. External refraction is found to result in compression of the fluctuations of the random field.
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arxiv:physics/0612228
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Author offers to complete research on a new method and cheap applicatory design for land and sea textile dams. The offered method for the protection of the USA's major seaport cities against hurricane storm surge waves, tsunamis, and other weather-related inundations is the cheapest (to build and maintain of all extant anti-flood barriers) and it, therefore, has excellent prospective applications for defending coastal cities from natural weather-caused disasters. It may also be a very cheap method for producing a big amount of cyclical renewable hydropower, land reclamation from the ocean, lakes, riverbanks, as well as land transportation connection of islands, and islands to mainland, instead of very costly over-water bridges and underwater tunnels.
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arxiv:physics/0701059
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We introduce nonlinear attractive effects into a spatial Prisoner's Dilemma game where the players located on a square lattice can either cooperate with their nearest neighbors or defect. In every generation, each player updates its strategy by firstly choosing one of the neighbors with a probability proportional to $\mathcal{A}^\alpha$ denoting the attractiveness of the neighbor, where $\mathcal{A}$ is the payoff collected by it and $\alpha$ ($\geq$0) is a free parameter characterizing the extent of the nonlinear effect; and then adopting its strategy with a probability dependent on their payoff difference. Using Monte Carlo simulations, we investigate the density $\rho_C$ of cooperators in the stationary state for different values of $\alpha$. It is shown that the introduction of such attractive effect remarkably promotes the emergence and persistence of cooperation over a wide range of the temptation to defect. In particular, for large values of $\alpha$, i.e., strong nonlinear attractive effects, the system exhibits two absorbing states (all cooperators or all defectors) separated by an active state (coexistence of cooperators and defectors) when varying the temptation to defect. In the critical region where $\rho_C$ goes to zero, the extinction behavior is power law-like $\rho_C$ $\sim$ $(b_c-b)^{\beta}$, where the exponent $\beta$ accords approximatively with the critical exponent ($\beta\approx0.584$) of the two-dimensional directed percolation and depends weakly on the value of $\alpha$.
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arxiv:physics/0701082
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'EPECUR' experiment setup is under construction at the beam line 322 of the ITEP proton synchrotron. The experiment requires several large area drift chambers to provide reasonable acceptance and fine pitch proportional chambers for beam particle tracking with total number of electronic channels of about 7000. New compact and cost effective readout system for these gaseous detectors was designed, prototyped and tested in the latest two years based on the modern technologies in analog and digital electronics, as well as in data transfer protocols. Mass production of the proportional chamber electronics is close to the end, while the boards for the drift chambers are manufactured in the amount to equip one 8-plane module. The paper presents the functional description of the whole DAQ system and its main parts together with some of the test results as an illustration of the excellent performance of the system. The appendix contains specific information which may be useful for the system users or code developers.
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arxiv:physics/0701108
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In this paper we describe the operation and performance of the HERA-B Outer Tracker, a 112674 channel system of planar drift tube layers. The performance of the HERA-B Outer Tracker system fullfilled all requirements for stable and efficient operation in a hadronic environment, thus confirming the adequacy of the honeycomb drift tube technology and of the front-end readout system. The detector was stably operated with a gas gain of 30000 in an Ar/CF4/CO2 (65:30:5) gas mixture, yielding a good efficiency for triggering and track reconstruction, larger than 95 % for tracks with momenta above 5 GeV/c. The hit resolution of the drift cells was 300 to 320 micrometers and the relative momentum resolution can be described as: sigma(p)/p (in %) = (1.61 +- 0.02) + (0.0051 +- 0.0006) p. At the end of the HERA-B running no aging effects in the Outer Tracker cells were observed.
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arxiv:physics/0701122
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We report a new method to measure the velocity of a fluid in the vicinity of a wall. The method, that we call Particle-Shadow Tracking (PST), simply consists in seeding the fluid with a small number of fine tracer particles of density close to that of the fluid. The position of each particle and of its shadow on the wall are then tracked simultaneously, allowing one to accurately determine the distance separating tracers from the wall and therefore to extract the velocity field. We present an application of the method to the determination of the velocity profile inside a laminar density current flowing along an inclined plane.
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arxiv:physics/0701131
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There is a clear positive correlation between boreal summer tropical Atlantic sea-surface temperature and annual hurricane numbers. This motivates the idea of trying to predict the sea-surface temperature in order to be able to predict future hurricane activity. In previous work we have used simple statistical methods to make 5 year predictions of tropical Atlantic sea surface temperatures for this purpose. We now compare these statistical SST predictions with SST predictions made by an ensemble mean of IPCC climate models.
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arxiv:physics/0701165
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Understanding how opinions spread through a community or how consensus emerges in noisy environments can have a significant impact on our comprehension of social relations among individuals. In this work a model for the dynamics of opinion formation is introduced. The model is based on a nonlinear interaction between opinion vectors of agents plus a stochastic variable to account for the effect of noise in the way the agents communicate. The dynamics presented is able to generate rich dynamical patterns of interacting groups or clusters of agents with the same opinion without a leader or centralized control. Our results show that by increasing the intensity of noise, the system goes from consensus to a disordered state. Depending on the number of competing opinions and the details of the network of interactions, the system displays a first- or a second-order transition. We compare the behavior of different topologies of interactions: one-dimensional chains, and annealed and complex networks.
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arxiv:physics/0701169
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We are developing a computer-aided detection (CAD) system for the identification of small pulmonary nodules in screening CT scans. The main modules of our system, i.e. a dot-enhancement filter for nodule candidate selection and a neural classifier for false positive finding reduction, are described. The preliminary results obtained on the so-far collected database of lung CT are discussed.
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arxiv:physics/0701245
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We have performed quantum molecular dynamics simulations for dense helium to study the nonmetal-to-metal transition at high pressures. We present new results for the equation of state and the Hugoniot curve in the warm dense matter region. The optical conductivity is calculated via the Kubo-Greenwood formula from which the dc conductivity is derived. The nonmetal-to-metal transition is identified at about 1 g/ccm. We compare with experimental results as well as with other theoretical approaches, especially with predictions of chemical models.
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arxiv:physics/0701248
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The ubiquity of modular structure in real-world complex networks is being the focus of attention in many trials to understand the interplay between network topology and functionality. The best approaches to the identification of modular structure are based on the optimization of a quality function known as modularity. However this optimization is a hard task provided that the computational complexity of the problem is in the NP-hard class. Here we propose an exact method for reducing the size of weighted (directed and undirected) complex networks while maintaining invariant its modularity. This size reduction allows the heuristic algorithms that optimize modularity for a better exploration of the modularity landscape. We compare the modularity obtained in several real complex-networks by using the Extremal Optimization algorithm, before and after the size reduction, showing the improvement obtained. We speculate that the proposed analytical size reduction could be extended to an exact coarse graining of the network in the scope of real-space renormalization.
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arxiv:physics/0702015
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The development of Information and Communication Technologies suggests some spectacular changes in the methods used for teaching scientific subjects. Nowadays, the development of software and hardware makes it possible to simulate processes as close to reality as we want. However, when we are trying to explain some complex physical processes, it is better to simplify the problem under study using simplified pictures of the total process by eliminating some elements that make it difficult to understand this process. In this work we focus our attention on the Doppler effect which requires the space-time visualization that is very difficult to obtain using the traditional teaching resources. We have designed digital simulations as a complement of the theoretical explanation in order to help students understand this phenomenon.
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arxiv:physics/0702036
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An ultrametric topology formalizes the notion of hierarchical structure. An ultrametric embedding, referred to here as ultrametricity, is implied by a natural hierarchical embedding. Such hierarchical structure can be global in the data set, or local. By quantifying extent or degree of ultrametricity in a data set, we show that ultrametricity becomes pervasive as dimensionality and/or spatial sparsity increases. This leads us to assert that very high dimensional data are of simple structure. We exemplify this finding through a range of simulated data cases. We discuss also application to very high frequency time series segmentation and modeling.
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arxiv:physics/0702064
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A transverse Zeeman slower composed of an array of compact discrete neodymium magnets is considered. A simple and precise model of such a slower based on magnetic dipoles is developed. The theory of a general Zeeman slower is modified to include spatial nonuniformity of the slowing laser beam intensity due to its convergence and absorption by slowed atoms. The slower needs no high currents or water cooling and the spatial distribution of its magnetic field can be adjusted. In addition the slower provides a possibility to cool the slowed atoms transversally along the whole length of the slower. Such a slower would be ideal for transportable optical atomic clocks and their future applications in space physics.
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arxiv:physics/0702074
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Within a simple model context, the sensitivity and stability of the thermohaline circulation to finite amplitude perturbations is studied. A new approach is used to tackle this nonlinear problem. The method is based on the computation of the so-called Conditional Nonlinear Optimal Perturbation (CNOP) which is a nonlinear generalization of the linear singular vector approach (LSV). It is shown that linearly stable thermohaline circulation states can become nonlinearly unstable and the properties of the perturbations with optimal nonlinear growth are determined. An asymmetric nonlinear response to perturbations exists with respect to the sign of finite amplitude freshwater perturbations, on both thermally dominated and salinity dominated thermohaline flows. This asymmetry is due to the nonlinear interaction of the perturbations through advective processes.
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arxiv:physics/0702083
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Traditional problem-based exams are not efficient instruments for assessing the "structure" of physics students' conceptual knowledge or for providing diagnostically detailed feedback to students and teachers. We present the Free Term Entry task, a candidate assessment instrument for exploring the connections between concepts in a student's understanding of a subject. In this task, a student is given a general topic area and asked to respond with as many terms from the topic area as possible in a given time; the "thinking time" between each term-entry event is recorded along with the response terms. The task was given to students from two different introductory physics classes. Response term thinking times were found to correlate with the strength of the association between two concepts. In addition, sets of thinking times from the task show distinct, characteristic patterns which might prove valuable for student assessment. We propose a quantitative dynamical model named the Matrix Walk Model which is able to match many aspects of the observed data. One particular feature of the data -- a distinct "spike" superimposed on the otherwise log-normal distribution of most thinking time sets -- has not been fit. The spike, other patterns observed in the data, and the proposed phenomenological model could all benefit from a grounding in cognitive theory.
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arxiv:physics/0702111
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In an effort to study the applicability of adaptive mesh refinement (AMR) techniques to atmospheric models an interpolation-based spectral element shallow water model on a cubed-sphere grid is compared to a block-structured finite volume method in latitude-longitude geometry. Both models utilize a non-conforming adaptation approach which doubles the resolution at fine-coarse mesh interfaces. The underlying AMR libraries are quad-tree based and ensure that neighboring regions can only differ by one refinement level. The models are compared via selected test cases from a standard test suite for the shallow water equations. They include the advection of a cosine bell, a steady-state geostrophic flow, a flow over an idealized mountain and a Rossby-Haurwitz wave. Both static and dynamics adaptations are evaluated which reveal the strengths and weaknesses of the AMR techniques. Overall, the AMR simulations show that both models successfully place static and dynamic adaptations in local regions without requiring a fine grid in the global domain. The adaptive grids reliably track features of interests without visible distortions or noise at mesh interfaces. Simple threshold adaptation criteria for the geopotential height and the relative vorticity are assessed.
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arxiv:physics/0702133
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We simulate the nonlinear dynamic responses in Kirchhoff rod by including the important effects due to inertia and kinematic coupling of tension and torsion. We begin by reviewing a dynamic rod model of a strand (length of cable or DNA) in the form of a 12th order partial differential equation system. Numerical solutions reveal the effects of dynamics on clamped strands due to slow movements of their ends. We note that inertia plays a critical role in this process, particularly under loading conditions that pass through an instability. For example, we simulated a dynamic trasition path between two possible equilibria of a clamped rod subject to very slow compression.
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arxiv:physics/0702201
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An analytical formulation for the band structure and Bloch modes in elliptically birefringent magnetophotonic crystals is presented. The model incorporates both the effects of gyrotropy and linear birefringence generally present in magneto-optic thin film devices. Full analytical expressions are obtained for the dispersion relation and Bloch modes in a layered stack photonic crystal and their properties are analyzed. It is shown that other models recently discussed in the literature are contained as special limiting cases of the formulation presented herein.
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arxiv:physics/0702230
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We describe the characteristics of low-cost ultra-high-power light emitting diodes (LEDs) for use in optical imaging experiments. We use the LEDs in experiments with bullfrog cardiac tissue and find that the signal-to-noise ratio is comparable to other commonly used illumination sources.
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arxiv:physics/0702241
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Efficient design and performance of electrically actuated MEMS devices necessitate accurate estimation of electrostatic forces on the MEMS structures. This in turn requires thorough study of the capacitance of the structures and finally the charge density distribution on the various surfaces of a device. In this work, nearly exact BEM solutions have been provided in order to estimate these properties of a parallel narrow beam structure found in MEMS devices. The effect of three-dimensionality, which is an important aspect for these structures, and associated fringe fields have been studied in detail. A reasonably large parameter space has been covered in order to follow the variation of capacitance with various geometric factors. The present results have been compared with those obtained using empirical parametrized expressions keeping in view the requirement of the speed of computation. The limitations of the empirical expressions have been pointed out and possible approaches of their improvement have been discussed.
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arxiv:physics/0703060
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It is hard for us humans to recognize things in nature until we have invented them ourselves. For image-forming optics, nature has made virtually every kind of lens humans have devised. But what about lensless "imaging"? Recently, we showed that a bare array of sensors on a curved substrate could achieve resolution not limited by diffraction- without any lens at all provided that the objects imaged conform to our a priori assumptions. Is it possible that somewhere in nature we will find this kind of vision system? We think so and provide examples that seem to make no sense whatever unless they are using something like our lensless imaging work.
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arxiv:physics/0703096
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Systems evolving according to the standard concept of biological or technological evolution are often described by catalytic evolution equations. We study the structure of these equations and find a deep relationship to classical thermodynamics. In particular we can demonstrate the existence of several distinct phases of evolutionary dynamics: a phase of fast growing diversity, one of stationary, finite diversity, and one of rapidly decaying diversity. While the first two phases have been subject to previous work, here we focus on the destructive aspects - in particular the phase diagram - of evolutionary dynamics. We further propose a dynamical model of diversity which captures spontaneous creation and destruction processes fully respecting the phase diagrams of evolutionary systems. The emergent timeseries show a Zipf law in the diversity dynamics, which is e.g. observable in actual economical data, e.g. in firm bankruptcy data. We believe the present model is a way to cast the famous qualitative picture of Schumpeterian economic evolution, into a quantifiable and testable framework.
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arxiv:physics/0703103
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Antiprotonic helium, a neutral exotic three-body system consisting of a helium nucleus, an electron and an antiproton, is being studied at the Antiproton Decelerator of CERN by the ASAUCSA collaboration. Using laser spectroscopy of the energy levels of the antiproton in this system and comparison to theory, a value of the antiproton-to-electron mass ratio with an error of 3 ppb could be obtained. This result agrees with the most precise measurement of the value of the proton and allows us to extract a limit of the equality of the proton and antiproton charge and mass of 2 ppb. Using microwave spectroscopy, the hyperfine structure of antiprotonic helium has been measured to 30 ppm. Experimental improvements are expected to soon provide a new value for the magnetic moment of the antiproton.
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arxiv:physics/0703127
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A new nanoscale device for fluctuation-enhanced sensing is proposed.
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arxiv:physics/0703140
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The effects of elasticity on filament thinning and breakup are investigated in microchannel cross flow. When a viscous solution is stretched by an external immiscible fluid, a low 100 ppm polymer concentration strongly affects the breakup process, compared to the Newtonian case. Qualitatively, polymeric filaments show much slower evolution, and their morphology features multiple connected drops. Measurements of filament thickness show two main temporal regimes: flow- and capillary-driven. At early times both polymeric and Newtonian fluids are flow-driven, and filament thinning is exponential. At later times, Newtonian filament thinning crosses over to a capillary-driven regime, in which the decay is algebraic. By contrast, the polymeric fluid first crosses over to a second type of flow-driven behavior, in which viscoelastic stresses inside the filament become important and the decay is again exponential. Finally, the polymeric filament becomes capillary-driven at late times with algebraic decay. We show that the exponential flow thinning behavior allows a novel measurement of the extensional viscosities of both Newtonian and polymeric fluids.
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arxiv:physics/0703161
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Using a single particle density distribution for a system of self-gravitating particles which ultimately forms a black hole, we from a condensed matter point of view derive the Schwarzschild radius and by including the quantum mechanical exchange energy we find a small correction to the Schwarzschild radius, which we designate as the skin of the black hole.
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arxiv:physics/0703173
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A compact liquid organic neutron spectrometer (CLONS) based on a single NE213 liquid scintillator (5 cm diam. x 5 cm) is described. The spectrometer is designed to measure neutron fluence spectra over the energy range 2-200 MeV and is suitable for use in neutron fields having any type of time structure. Neutron fluence spectra are obtained from measurements of two-parameter distributions (counts versus pulse height and pulse shape) using the Bayesian unfolding code MAXED. Calibration and test measurements made using a pulsed neutron beam with a continuous energy spectrum are described and the application of the spectrometer to radiation dose measurements is discussed.
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arxiv:physics/0703211
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We first define the functions which ensure the transformation of momentum and energy of a tardyon, the transformation of the wave vector and the frequency of the associated wave. Having done this, we show that they ensure the relativistic invariance of the quotient between momentum and wave vector and between energy and frequency if the product between particle velocity u and phase velocity w is a relativistic invariant (uw=c^2), a condition which is a natural combination of special relativity theory and quantum mechanics.
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arxiv:physics/0703228
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We have measured the spectral correlations and intensity statistics of random lasing modes in weakly scattering systems, and compared them to those of the amplified spontaneous emission spikes. Their dramatic differences revealed the distinct physical mechanisms. We find that local excitation of a weakly scattering system may greatly reduce the number of lasing modes even without absorption outside the pumped region. The lasing modes can be very different from the quasimodes of the passive system due to selective amplification of the feedback from the scatterers within the local gain region.
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arxiv:physics/0703255
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It is noted that the results of recent experiments on the enhancement of turbulent kinetic energy (TKE) dissipation below surface waves can be stated as follows. TKE dissipation is enhanced by a factor $15 H_{ws}/z$ at depths $0.5 H_{ws} < z < 20 H_{ws}$ with respect to the wall-layer result $\epsilon = u_{*w}^3/\kappa z$, where $u_{*w}$ is the friction velocity in water and $H_{ws}$ is the significant wind-sea wave height. For open ocean conditions, this reduces in most cases to an enhancement factor $10^6 u_{*w}^2/gz \approx U_{10}^2/gz$.
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arxiv:physics/9610002
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Using the Unruh-DeWitt detector, it is shown that a universal and continuous Lorentz transformaion of temperature cannot exist for black-body radiation. Since any valid Lorentz transformation of temperature must be able to deal with black-body radiation, it is concluded that a universal and continuous temperature transformation does not exist.
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arxiv:physics/9610016
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A simple analytical solution for the problem of multiphoton detachment from negative ions by a linearly polarized laser field is found. It is valid in the wide range of intensities and frequencies of the field, from the perturbation theory to the tunneling regime, and is applicable to the excess-photon as well as near-threshold detachment. Practically, the formulae are valid when the number of photons is greater than two. They produce the total detachment rates, relative intensities of the excess-photon peaks, and photoelectron angular distributions for the hydrogen and halogen negative ions, in agreement with those obtained in other, more numerically involved calculations in both perturbative and non-perturbative regimes. Our approach explains the extreme sensitivity of the multiphoton detachment probability to the asymptotic behaviour of the bound-state wave function. Rapid oscillations in the angular dependence of the $n$-photon detachment probability are shown to arise due to interference of the two classical trajectories which lead to the same final state after the electron emerges at the opposite sides of the atom when the field is close to maximal.
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arxiv:physics/9702002
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Book Review of Quantum Field Theory by Lewis H. Ryder. An observation on Ryder's derivation of Dirac equation is made. The review ends as, "A rare combination of a thorough understanding and appreciation of the essential logical structure of quantum field theory and deep pedagogic skills have intermingled to create a masterpiece on the elementary introduction to quantum field theory in less than five hundred pages... . Without reservations, I give my strongest recommendation to every beginning student of physics to acquire and read Quantum Field Theory by L. H. Ryder."
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arxiv:physics/9702005
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Einstein equations for several matter sources in Robertson-Walker and Bianchi I type metrics, are shown to reduce to a kind of second order nonlinear ordinary differential equation $\ddot{y}+\alpha f(y)\dot{y}+\beta f(y)\int{f(y) dy}+\gamma f(y)=0$. Also, it appears in the generalized statistical mechanics for the most interesting value q=-1. The invariant form of this equation is imposed and the corresponding nonlocal transformation is obtained. The linearization of that equation for any $\alpha, \beta$ and $\gamma$ is presented and for the important case $f=by^n+k$ with $\beta=\alpha ^2 (n+1)/((n+2)^2)$ its explicit general solution is found. Moreover, the form invariance is applied to yield exact solutions of same other differential equations.
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arxiv:physics/9702029
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We analyze the supersymmetry and the shape invariance of the potentials of the (1+1) relativistic oscillators we have recently proposed.
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arxiv:physics/9705011
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We calculate an effective electric field on the unpaired electron in the YbF molecule. This field determines sensitivity of the molecular experiment to the electric dipole moment of the electron. We use experimental value of the spin-doubling constant to estimate the admixture of the configuration with the hole in the 4f-shell of Ytterbium to the ground state of the molecule. This admixture reduces the field by 7%. Our value for the effictive field is 5.1 a.u. = 2.5 10^{10} V/cm.
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arxiv:physics/9705042
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In a preceeding paper alternative reflections on gravitation were developed. There it was assumed that the primary interaction between two masses is not of attractive but of repulsive nature. The repulsive force results from the impuls transfer produced by the gravitational radiation which is emitted and absorbed by both masses. The observed attractive force between the two masses according to Newton`s law of gravitation, however, is a secondary effect and a consequence of the existence of all the masses in the universe. The mutual screening of the gravitational radiation of all masses of the universe by the two masses under consideration leads to the gravitational attraction between them. The balance between primary, repulsive and secondary, attractive forces can stabilize highly concentrated spherical mass accumulations with a linear dependence of their mass on the square of their diameter. Such objects can really be observed in the universe in the form of globular star clusters, elliptical galaxies and spherical clusters of galaxies. The scatter of the data of every group is rather large. But the collection of the objects of all three groups, reaching from the smallest globular star cluster to the largest spherical cluster of galaxies, with masses differing by almost 12 orders of magnitude, clearly shows the proposed mass-diameter relation.
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arxiv:physics/9706001
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We submit the viewpoint that, perhaps, some of the controversies in gravitation occurred during this century are not due to insufficiencies of Einstein's field equations, but rather to insufficiencies in the mathematics used for their treatment. For this purpose we treat the same equations with the novel, broader isomathematics and related isominkowskian geometry, and show an apparently final resolution in favor of existing relativities of controversies such as: the lack of invariance of the basic units of space and time; lack of compatibility between gravitational and relativistic conservation laws; lack of meaningful relativistic limit of gravitation; and others. However, an apparent necessary condition for the resolution of these controversies is the abandonment of the notion of curvature used in this century in favor of a conceptual and mathematical broader notion. A number of intriguing implications and experimental verifications are pointed out.
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arxiv:physics/9707018
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An extension of the traditional modulation transfer function (MTF), the detective MTF, is proposed for the evaluation of the resolution of X-ray imaging detectors with non-uniform efficiency on the scale of individual detector elements. The dMTF is shown to give a better representation than does the MTF of the improved resolution reported when the readout of the detectors is enhanced.
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arxiv:physics/9708025
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Full size single-sided GaAs microstrip detectors with integrated coupling capacitors and bias resistors have been fabricated on 3'' substrate wafers. PECVD deposited SiO_2 and SiO_2/Si_3N_4 layers were used to provide coupling capacitaces of 32.5 pF/cm and 61.6 pF/cm, respectively. The resistors are made of sputtered CERMET using simple lift of technique. The sheet resistivity of 78 kOhm/sq. and the thermal coefficient of resistance of less than 4x10^-3 / degree C satisfy the demands of small area biasing resistors, working on a wide temperature range.
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arxiv:physics/9709041
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Reported here are results of theoretical calculations on the hexaaquoferric complex and deprotonated products to investigate the molecular mechanisms of hydrolysis of ferric ion in water. The combination of density functional electronic structure techniques and a dielectric continuum model for electrostatic solvation applied to the Fe(H$_2$O)$_6$$^{3+}$ complex yields -1020~kcal/mol (experimental values -1037~kcal/mol to -1019~kcal/mol) for the absolute free energy of the aqueous ferric ion. The predicted reaction energy change for the first hydrolysis is 2 kcal/mol (compared to 3 kcal/mol experimental). For the second hydrolysis, we found an unexpected low energy isomer of Fe(H$_2$O)$_4$(OH)$_2$$^{+}$ with five ligands in the inner sphere and one water outside. The cis and trans isomers are, respectively, slightly lower and higher in energy. Extrusion of the additional water to the outer sphere is nearly thermoneutral. The reaction free energy for the second hydrolysis is predicted in the range 16-18~kcal/mol, higher than the experimental value of 5~kcal/mol. Since the theoretical predictions for the second hydrolysis are higher than experimental values and novel structures were encountered, we argue that conformational entropy is important in these reactions.
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arxiv:physics/9710026
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Two simple, interpolatory-like linearizations are shown for the simple pendulum which can be used for any initial amplitude.
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arxiv:physics/9710029
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The purpose of this paper is to provide definitions for, and proofs of, the asymptotic formulae given by Edmonds, which relate the 3j and 6j symbols to rotation matrices.
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arxiv:physics/9710037
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The distinction between point and line resolution in transmission electron microscopy (TEM) arises because an ability to image sub-0.2 nm fringes is a necessary, but not a sufficient, condition for imaging individual atoms. In scanned tip microscopy, as in TEM, empirical data on instrument response should precede assertions about point resolution. In the ``slow scan limit'', time-domain noise and geometry effects decouple, and tip shape can take on the role of a 2-dimensional impulse response function. We indicate here that nuclear track pits can be used to quantitatively measure tip geometry with nanometer-scale resolution in three dimensions, that stationary tip images provide a robust measure of time-domain instabilities, and that when these data are taken before and after imaging an unknown, images with instrument response quantitatively constrained by experiment are possible. Specimen-induced tip effects also become measurable in situ.
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arxiv:physics/9712003
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The relativistic extension of non-relativistic hydrodynamics suffers from notorious difficulties. In non-relativistic hydrodynamics where difficulties also abound, it has proved a useful supplement to study lattice models which can imitate viscous fluid flow. In this paper we construct a relativistic spacetime lattice and construct a dynamics of points, thus a relativistic cellular automaton over it, to model relativistic fluid flow. A simple example is also explicitly studied, and some numerical results with figures are shown in the last section.
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arxiv:physics/9712018
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