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Owing to its numerical simplicity, a two-dimensional two-electron model atom, with each electron moving in one direction, is an ideal system to study non-perturbatively a fully correlated atom exposed to a laser field. Frequently made assumptions, such as the ``single active electron''- approach and calculational approximations, e.g. time dependent density functional theory or (semi-) classical techniques, can be tested. In this paper we examine the multiphoton short pulse-regime. We observe ``non-sequential'' ionization, i.e.\ double ionization at lower field strengths as expected from a sequential, single active electron-point of view. Since we find non-sequential ionization also in purely classical simulations, we are able to clarify the mechanism behind this effect in terms of single particle trajectories. PACS Number(s): 32.80.Rm
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arxiv:physics/9712031
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In the present report the author presents a simple and systematically defined formula for the fine structure constant based only on the number $\pi$. The difference between the suggested value and the currently known experimental one is about 60 times smaller than the uncertainty interval.
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arxiv:physics/9712044
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The Reply to G. W. Bruhn is added.
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arxiv:physics/9801024
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We present an approach to the origin of inertia involving the electromagnetic component of the quantum vacuum and propose this as an alternative to Mach's principle. Preliminary analysis of the momentum flux of the classical zero-point radiation impinging on accelerated objects as viewed by an inertial observer suggests that the resistance to acceleration attributed to inertia may be at least in part a force of opposition originating in the vacuum. This analysis avoids the ad hoc modeling of particle-field interaction dynamics used previously to derive a similar result. This present approach is not dependent upon what happens at the particle point, but on how an external observer assesses the kinematical characteristics of the zero-point radiation impinging on the accelerated object. A relativistic form of the equation of motion results from the present analysis. Its covariant form yields a simple result that may be interpreted as a contribution to inertial mass. Our approach is related by the principle of equivalence to Sakharov's conjecture of a connection between Einstein action and the vacuum. The argument presented may thus be construed as a descendant of Sakharov's conjecture by which we attempt to attribute a mass-giving property to the electromagnetic component -- and possibly other components-- of the vacuum. In this view the physical momentum of an object is related to the radiative momentum flux of the vacuum instantaneously contained in the characteristic proper volume of the object. The interaction process between the accelerated object and the vacuum (akin to absorption or scattering of electromagnetic radiation) appears to generate a physical resistance (reaction force) to acceleration suggestive of what has been historically known as inertia.
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arxiv:physics/9802030
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This paper has been withdrawn by the authors until some changes are made.
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arxiv:physics/9802032
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Induced representations of Brauer algebra $D_{f}(n)$ from $S_{f_{1}}\times S_{f_{2}}$ with $f_{1}+f_{2}=f$ are discussed. The induction coefficients (IDCs) or the outer-product reduction coefficients (ORCs) of $S_{f_{1}}\times S_{f_{2}}\uparrow D_{f}(n)$ with $f\leq 4$ up to a normalization factor are derived by using the linear equation method. Weyl tableaus for the corresponding Gel'fand basis of SO(n) are defined. The assimilation method for obtaining CG coefficients of SO(n) in the Gel'fand basis for no modification rule involved couplings from IDCs of Brauer algebra are proposed. Some isoscalar factors of $SO(n)\supset SO(n-1)$ for the resulting irrep $[\lambda_{1},~\lambda_{2},~ \lambda_{3},~\lambda_{4},\dot{0}]$ with $\sum\limits_{i=1}^{4}\lambda_{i}\leq .
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arxiv:physics/9803045
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We theoretically study reflection of light by a phase-conjugating mirror preceded by a partially reflecting normal mirror. The presence of a suitably chosen normal mirror in front of the phase conjugator is found to greatly enhance the total phase-conjugate reflected power, even up to an order of magnitude. Required conditions are that the phase-conjugating mirror itself amplifies upon reflection and that constructive interference of light in the region between the mirrors takes place. We show that the phase-conjugate reflected power then exhibits a maximum as a function of the transmittance of the normal mirror.
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arxiv:physics/9804003
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A new measurement of the 1S-2S energy splitting of muonium by Doppler-free two-photon spectroscopy has been performed at the Rutherford Appleton Laboratory in Chilton, Didcot, UK. Increased accuracy is expected compared to a previous experiment. Spectroscopy of this transistion promises an improvement of the muon mass value.
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arxiv:physics/9805020
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A general model is presented for coupling of high-$Q$ whispering-gallery modes in optical microsphere resonators with coupler devices possessing discrete and continuous spectrum of propagating modes. By contrast to conventional high-Q optical cavities, in microspheres independence of high intrinsic quality-factor and controllable parameters of coupling via evanescent field offer variety of regimes earlier available in RF devices. The theory is applied to the earlier-reported data on different types of couplers to microsphere resonators and complemented by experimental demonstration of enhanced coupling efficiency (about 80%) and variable loading regimes with Q>10^8 fused silica microspheres.
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arxiv:physics/9805030
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This is a pedagogical paper which explains some ideas in cosmology at a level accessible to undergraduate students. It does not use general relativity, but uses the ideas of Newtonian cosmology worked out by Milne and McCrea. The cosmological constant is also introduced within a Newtonian framework. Following standard quantization procedures the Wheeler-DeWitt equation in the minisuperspace approximation is derived for empty and non-empty universes.
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arxiv:physics/9806004
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The Clifford pentads of the 4X4 complex matrices define the current vectors of the particles. The weak isospin transformation divides the particles on two components, which scatter in the 2-dimensional antidiagonal Clifford matrices space. A physics objects move in the 3-dimensional diagonal Clifford matrices space. This sectioning of the 5-dimensional space on the 3-dimensional and the 2-dimensional subspaces defines the Newtonian gravity principle. The Clifford pentads sextet contains single light pentad and three chromatic pentads. The Cartesian frame rotations confound the chromatic pentads. The combination of the chromatic particles (the hadron monad) exists, which behaves as the particle for such rotations. PACS 12.15.-y 12.38.-t 12.39.-x 12.40.-q 04.20.-q
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arxiv:physics/9806007
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We present a detailed study of the effects of the initial distribution on the kinetic evolution of the irreversible reaction A+B -> 0 in one dimension. Our analytic as well as numerical work is based on a reaction-diffusion model of this reaction. We focus on the role of initial density fluctuations in the creation of the macroscopic patterns that lead to the well-known kinetic anomalies in this system. In particular, we discuss the role of the long wavelength components of the initial fluctuations in determining the long-time behavior of the system. We note that the frequently studied random initial distribution is but one of a variety of possible distributions leading to interesting anomalous behavior. Our discussion includes an initial distribution with correlated A-B pairs and one in which the initial distribution forms a fractal pattern. The former is an example of a distribution whose long wavelength components are suppressed, while the latter exemplifies one whose long wavelength components are enhanced, relative to those of the random distribution.
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arxiv:physics/9806012
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The multigrid algorithm is a multilevel approach to accelerate the numerical solution of discretized differential equations in physical problems involving long-range interactions. Multiresolution analysis of wavelet theory provides an efficient representation of functions which exhibit localized bursts of short length-scale behavior. Applications such as computing the electrostatic field in and around a molecule should benefit from both approaches. In this work, we demonstrate how a novel interpolating wavelet transform, which in itself is the synthesis of finite element analysis and wavelet theory, may be used as the mathematical bridge to connect the two approaches. The result is a specialized multigrid algorithm which may be applied to problems expressed in wavelet bases. With this approach, interpolation and restriction operators and grids for the multigrid algorithm are predetermined by an interpolating multiresolution analysis. We will present the new method and contrast its efficiency with standard wavelet and multigrid approaches.
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arxiv:physics/9806034
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The regional phase Lg is used to estimate location and magnitude for sources closer than 1500 km. The complexity of Lg waveforms makes it difficult to consistently determine Lg arrival time, thus affecting source location with a single station or array. This study tests an automatic method for timing Lg arrivals using wavelet transforms to decompose the Lg signal into its components localized both in time and scale. A Continuous Wavelet Transform (CWT) using a Daubechies order two (db2) wavelet is applied to 10 seconds of raw data, containing the start of Lg. Initial positioning of the window is obtained using the standard Lg travel time tables. The coefficients at scale 8 from the db2 decomposition are squared and the resulting time series is represented by an approximation of the 4'th level Discrete Wavelet Transform (DWT) using a Haar wavelet. A threshold detector is then applied to the resulting time series to determine the Lg arrival time. The method was tested using well located earthquakes (USGS) and explosions from known mines (mb less than 4.0), recorded on the vertical components at TXAR (Lajitas, Texas) and PDAR (Pinedale, Wyoming) arrays. The Lg arrival time was automatically picked with a standard deviation of less than 1.5 seconds (less than 10 km location error) for well known locations. Location errors are larger with the increase in distance and smaller with the increase in signal to noise ratio of events.
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arxiv:physics/9806041
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In 1923 Louis de Broglie (1892-1987) discovered the material waves and six years later received the Nobel price for this discovery. Apart these well known facts this French physicist nevertheless seems to be forgotten. Details of his life are as unknown as his efforts to describe quantum mechanics in a deterministic and objective way. Especially the actual discussion concerning the interpretation of quantum mechanics seems to justify a deeper occupation with the scientific work of Louis de Broglie. In this context the important influence of Albert Einstein is of special interest; for his photons announce the existence of material waves and it may surprise that Einstein himself did not postulate them. The basis of this short scientific biography are the publications of de Broglie (a complete bibliography is given at the end), some more or less short memories of his students and some unpublished documents found in the "Archives de l'Academie des Sciences" at Paris. The original text of the correspondence between de Broglie and Einstein is enclosed in German translation in the appendix.
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arxiv:physics/9807012
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The analytical and numerical investigations of the energy loss rate of the test particle in a magnetized electron plasma are developed on the basis of the Vlasov-Poisson equations, and the main results are presented. The Larmor rotation of a test particle in a magnetic field is taken into account. The analysis is based on the assumption that the energy variation of the test particle is much less than its kinetic energy. The obtained general expression for stopping power is analyzed for three cases: (i) the particle moves through a collisionless plasma in a strong homogeneous magnetic field; (ii) the fast particle moves through a magnetized collisionless plasma along the magnetic field; and (iii) the particle moves through a magnetized collisional plasma across a magnetic field. Calculations are carried out for the arbitrary test particle velocities in the first case, and for fast particles in the second and third cases. It is shown that the rate at which a fast test particle loses energy while moving across a magnetic field may be much higher than the loss in the case of motion through plasma without magnetic field.
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arxiv:physics/9807024
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We derive the force exerted in the background plasma by an arbitrary distribution of non interacting quasi-particles, corresponding to either collective excitations of the plasma (plasmons, phonons) or em dressed particles (photons, neutrinos). Our approach is based on the effective Hamiltonian describing the quasi-classical dynamics of the individual particles in the presence of a background medium. We recover the usual results for the relativistic ponderomotive force of a photon gas, and we derive the force, due to weak interactions, exerted by the electron-neutrinos in a background medium containing electrons, positrons and neutrons with arbitrary distribution functions. Generalization to other background species and other neutrino flavors is also discussed.
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arxiv:physics/9807049
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The time-dependent local-density approximation (TDLDA) is applied to the optical response of conjugated carbon molecules in the energy range of 0-30 eV, with calculations given for carbon chains, polyenes, retinal, benzene and C_60. The major feature of the spectra, the collective pi-pi* transition, is seen at energies ranging from below 2 to 7 eV, and is reproduced by the theory to a few tenths of an eV with a good account of systematic trends. However, there is some indication that TDLDA predicts too much fragmentation of the strength function in large molecules. Transition strengths are reproduced with a typical accuracy of 20%. The theory also predicts a broad absorption peak in the range 15-25 eV, and this feature agrees with experiment in the one case where quantitative data is available (benzene).
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arxiv:physics/9808015
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The interaction of intense fs laser pulses with thin foils that have an imposed deformation is compared with thick targets that develop bow shocks. Both target types yield good absorption. Up to 80% absorption is obtained for a $0.2\mu m$ thick, 15 times over-dense foil at $4 \cdot 10^{18} W/cm^2$. A value of 50% is obtained for a $4 \mu m$ thick, 2 times over-dense thick target at $10^{18} W/cm^2$. For comparable extension and curvature of the laser-plasma interfaces absorption levels in both targets become similar. In both absorption scales weakly with intensity and density. Energy transport in thin foils and thick targets, however, is different.
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arxiv:physics/9808039
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The convergent close-coupling method is applied to the calculation of fully differential cross sections for ionization of atomic hydrogen by 15.6 eV electrons. We find that even at this low energy the method is able to yield predictive results with small uncertainty. As a consequence we suspect that the experimental normalization at this energy is approximately a factor of two too high.
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arxiv:physics/9810053
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We study the modifications of synchrotron radiation of charges in a storage ring as they are cooled. The pair correlation lengths between the charges are manifest in the synchrotron radiation and coherence effects exist for wavelengths longer than the coherence lengths between the charges. Therefore the synchrotron radiation can be used as a diagnostic tool to determine the state (gas, liquid, crystal) of the charged plasma in the storage ring. We show also that the total power of the synchrotron radiation is enormously reduced for crystallized beams. This opens the possibility of accelerating particles to ultra-relativistic energies using small-sized cyclic accelerators.
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arxiv:physics/9811007
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The performance of hybrid GaAs pixel detectors as X-ray imaging sensors were investigated at room temperature. These hybrids consist of 300 mu-m thick GaAs pixel detectors, flip-chip bonded to a CMOS Single Photon Counting Chip (PCC). This chip consists of a matrix of 64 x 64 identical square pixels (170 mu-m x 170 mu-m) and covers a total area of 1.2 cm**2. The electronics in each cell comprises a preamplifier, a discriminator with a 3-bit threshold adjust and a 15-bit counter. The detector is realized by an array of Schottky diodes processed on semi-insulating LEC-GaAs bulk material. An IV-charcteristic and a detector bias voltage scan showed that the detector can be operated with voltages around 200 V. Images of various objects were taken by using a standard X-ray tube for dental diagnostics. The signal to noise ratio (SNR) was also determined. The applications of these imaging systems range from medical applications like digital mammography or dental X-ray diagnostics to non destructive material testing (NDT). Because of the separation of detector and readout chip, different materials can be investigated and compared.
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arxiv:physics/9812039
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The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides continued work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (CoM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay ($\pi \to \mu \nu_{\mu}$) channel, muon cooling, acceleration, storage in a collider ring and the collider detector. We also present theoretical and experimental R & D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the R & D since the Feasibility Study of Muon Colliders presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].
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arxiv:physics/9901022
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We study how the spectral properties of resonance fluorescence propagate through a two-atom system. Within the weak-driving-field approximation we find that, as we go from one atom to the next, the power spectrum exhibits both sub-natural linewidth narrowing and large asymmetries while the spectrum of squeezing narrows but remains otherwise unchanged. Analytical results for the observed spectral features of the fluorescence are provided and their origin is thoroughly discussed.
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arxiv:physics/9902020
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A new algorithm for determining the eigenstates of n-dimensional billiards is presented. It is based on the application of the Cauchy theorem for the determination of the null space of the boundary overlap matrix. The method is free from the limitations associated with the shape of the billiard and could be applied even for nonconvex geometries where other algorithms face difficulties. Moreover it does not suffer from the existence of eigenvalue degeneracies which is another serious shortcoming of many methods. In the paper we apply the algorithm to a few simple cases where the analytical solutions exist. Numerical solutions have been investigated for the case of annular billiard.
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arxiv:physics/9902057
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The time variation of the gravitational constant G in the recently discussed large number cosmologies accounts for the galactic rotational velocity curves without invoking dark matter and also for effects like the precession of the perhelion of Mercury.
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arxiv:physics/9904022
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It is shown that recently measured cross sections for double ionization of negative ions ($H^-, O^-$, and $C^-$) possess a universal shape when plotted in suitable dimensionless units. The shape can be represented with a simple analytical function, following the same principles as it has been done in establishing a universal shape function for single ionization [Rost and Pattard 1997 Phys. Rev. A {\bf 55} R5]. Thereby, it is demonstrated that direct double ionization dominates the cross section for the targets considered.
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arxiv:physics/9904032
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A discontinuity of a turbulent ideal fluid is considered. It is supposed to be split and dispersed, or spread in the stochastic environment forming a gas without hydrostatic pressure. Two equal-mass fragments of a discontinuity are indistinguishable from each other. A gas, that possesses such properties, must behave itself as the Madelung medium.
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arxiv:physics/9904034
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It is shown in this paper that recent results that below the Fermi temperature, Fermions obey anomalous semionic statistics, could explain such apparently diverse phenomena as the magnetism of Pulsars and White Dwarfs on the one hand and earth like planets, on the other.
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arxiv:physics/9904059
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In this paper we first show that the usual three dimensionality of space, which is taken for granted, results from the spinorial behaviour of Fermions, which constitute the material content of the universe. It is shown that the resulting three dimensionality rests on two factors which have been hitherto ignored, viz., a Machian or holistic property and the stochastic underpinning of the universe itself. However the dimensionality is scale dependent in the sense that at very large scales, or at very small scales, we encounter a different dimensionality, as indeed is borne out by observation and experiment. For example the large scale structures in the universe are cellular in nature on the one hand, and we encounter fractional charges and handedness at very small scales. Finally it is shown how fractal dimensions can emerge and as an illustrative example it is shown how this could explain the magnetism of objects like Planets on the one hand and White Dwarf stars and Pulsars on the other.
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arxiv:physics/9908004
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An important question of theoretical physics is whether sound is able to propagate in vacuums at all and if this is the case, then it must lead to the reinterpretation of one zero-restmass particle which corresponds to vacuum-sound waves. Taking the electron-neutrino as the corresponding particle, its observed non-vanishing rest-energy may only appear for neutrino-propagation inside material media. The idea may also influence the physics of dense matter, restricting the maximum speed of sound, both in vacuums and in matter to the speed of light.
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arxiv:physics/9908010
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High energy muon colliders, such as the TeV-scale conceptual designs now being considered, are found to produce enough high energy neutrinos to constitute a potentially serious off-site radiation hazard in the neighbourhood of the accelerator site. A general characterization of this radiation hazard is given, followed by an order-of-magnitude calculation for the off-site annual radiation dose and a discussion of accelerator design and site selection strategies to minimize the radiation hazard.
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arxiv:physics/9908017
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We present a simple model based on a reaction-diffusion equation to explain pattern formation in a multicellular bacterium (Streptomyces). We assume competition for resources as the basic mechanism that leads to pattern formation; in particular we are able to reproduce the spatial pattern formed by bacterial aerial mycelium in case of growth in minimal (low resources) and maximal (large resources) culture media.
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arxiv:physics/9909012
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This pedagogical review presents the Shell Correction Method (SCM) and variants thereof, appropriate for describing shape deformations and electronic shell effects, energetics and decay pathways of metal-cluster fragmentation processes (e.g., monomer/dimer dissociation and fission). The experimental trends are compared to the theoretical SCM interpretations, and in addition theoretical results for fission from first-principles molecular-dynamics simulations are discussed. Some latest insights concerning the importance of electronic-entropy and finite-temperature effects are given special attention.
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arxiv:physics/9909022
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When the Hamiltonian of a system is represented by a finite matrix, constructed from a discrete basis, the matrix representation of the resolvent covers only one branch. We show how all branches can be specified by the phase of a complex unit of time. This permits the Hamiltonian matrix to be constructed on a real basis; the only duty of the basis is to span the dynamical region of space, without regard for the particular asymptotic boundary conditions that pertain to the problem of interest.
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arxiv:physics/9909028
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Relying on a fundamental empirical identity of heavy and inertial mass it is proposed to bring a status of general theory of relativity (GTR) of Einstein up to a level of Unified Field Theory. To do this, a thoroughgoing revision of physical interpretation of energy-momentum tensor components within GTR is required. A complete system of equations for numerical simulation of the hierarchical structure of the real universe on the basis of curvature tensor invariants is proposed.
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arxiv:physics/9909040
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The physical idea of the natural origin of diseases and deaths has been presented. The fundamental microscopical reason is the destruction of any metastable state by thermal activation of a nucleus of a nonreversable change. On the basis of this idea the quantitative theory of age dependence of death probability has been constructed. The obtained simple Death Laws are very accurately fulfilled almost for all known diseases.
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arxiv:physics/9910008
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An interpretation of the formation of halo in accelerators based on quantum-like theory by a diffraction model is given in terms of the transversal beam motion. Physical implications of the longitudinal dynamics are also examined.
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arxiv:physics/9910026
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Bayesian inference is applied to the level fluctuations of two coupled microwave billiards in order to extract the coupling strength. The coupled resonators provide a model of a chaotic quantum system containing two coupled symmetry classes of levels. The number variance is used to quantify the level fluctuations as a function of the coupling and to construct the conditional probability distribution of the data. The prior distribution of the coupling parameter is obtained from an invariance argument on the entropy of the posterior distribution.
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arxiv:physics/9910035
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Crater has shown that, for two particles (with masses $m_1$ and $m_2$) in a Coulombic bound state, the charge distribution is equal to the sum of the two charge distributions obtained by taking $m_1\to\infty$ and $m_2\to\infty$ respectively, while keeping the same Coulombic potential. We provide a simple scaling criterion to determine whether an arbitrary Hamiltonian possesses this property. In particular we show that, for a Coulombic system, fine structure corrections preserve this Crater property while two-particle relativistic corrections and/or hyperfine corrections may destroy it.
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arxiv:physics/9910038
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The presence of skew quadrupole fields will linearly couple the x and y motions. The x and y motions can then be written as the sum of two normal modes >. This paper presents analytical perturbation theory results for the tunes of the normal modes. The results for the normal mode tunes are first found correct to lowest order in the skew quadrupole fields. The results are then carried one step further to include the next higher order terms in the skew quadrupole fields. These analytical results show that for the higher order shift in the tune, the important harmonics of the skew quadrupole field are the harmonics near the sum of the tunes. However the harmonics closest to the sum of the tunes do not contribute to the higher order tune splitting, the seperation of the tunes, as they shift the two tunes about equally.This results in a lack of a dominant harmonic for the higher order part of the tune splitting, which complicates the understanding and correction of the higher order part of the tune splitting.
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arxiv:physics/9910047
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We describe the object-oriented implementation of a higher-order finite-difference density-functional code in Fortran 90. Object-oriented models of grid and related objects are constructed and employed for the implementation of an efficient one-way multigrid method we have recently proposed for the density-functional electronic-structure calculations. Detailed analysis of performance and strategy of the one-way multigrid scheme will be presented.
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arxiv:physics/9911031
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Physical processes ranging from the Lamb shift to the energy loss dE/dx of a charged particle traversing a plasma entail processes that occur over a wide range of energy or length scales. Different physical mechanisms dominate at one or the other end of this range. For example, in the energy loss problem, soft collisions that are screened by collective effects are important at large distances, while at short distances hard collisions are important where the exact details of the single-particle interactions must be taken into account. We introduce a novel application of dimensional continuation. The soft processes dominate at all scales when the spatial dimension \nu is less than 3, and we use them to compute the result to leading order for \nu < 3. On the other hand, the hard processes dominate at all scales for \nu > 3, and we use them to compute the result to leading order for these spatial dimensions. We then explain why the sum of the analytic continuation of these disparate mechanisms yields the correct leading-order result for the physical limit at \nu = 3 dimensions. After applying this new method to the energy loss problem in some detail, we then show how it also provides a very short and easy way to compute the Lamb shift.
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arxiv:physics/9911056
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In nonrelativistic approximation one-dimensional motion of Sommerfeld sphere in the case of potential barrier is numerically investigated. The effect of classical tunneling is confirmed once more - Sommerfeld sphere overcomes the barrier and finds itself in the forbidden, from classical point of view, area.
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arxiv:physics/9911059
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We propose a new spectroscopic method for measuring weak transitions in cold and trapped atoms, which exploits the long interaction times and tight confinement offered by dark optical traps together with an electron shelving technique to achieve extremely high sensitivity. We demonstrate our scheme by measuring a 5S_{1/2}-> 5D_{5/2} two-photon transition in cold Rb atoms trapped in a new single-beam dark optical trap, using an extremely weak probe laser power of 25 micro-Watt. We were able to measure transitions with as small excitation rate as 0.09 sec^(-1).
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arxiv:physics/9912002
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A simple model which can explain the observed vertical distribution and size spectrum of atmospheric aerosol has been proposed. The model is based on a new physical hypothesis for the vertical mass exchange between the troposphere and the stratosphere. The vertical mass excange takes place through a gravity wave feedback mechanism. There is a close agreement between the model predicted aerosol distribution and size spectrum and the observed distributions.
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arxiv:physics/9912014
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Nonlinear relativistic ionization phenomena induced by a strong laser radiation with elliptically polarization are considered. The starting point is the classical relativistic action for a free electron moving in the electromagnetic field created by a strong laser beam. The application of the relativistic action to the classical barrier-suppression ionization is briefly discussed. Further the relativistic version of the Landau-Dykhne formula is employed to consider the semiclassical sub-barrier ionization. Simple analytical expressions have been found for: (i) the rates of the strong-field nonlinear ionization including relativistic initial and final state effects; (ii) the most probable value of the components of the photoelectron final state momentum; (iii) the most probable direction of photoelectron emission and (iv) the distribution of the photoelectron momentum near its maximum value.
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arxiv:physics/9912036
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Considerations on the complementary time-dependent coordinate transformations emboding Lorentz transformation (LT) show that the relativistic energy-momentum relationship, implicitly the relativistic mass and energy, do not depend on the square root appearing in LT, being associated to the absolute motion of a particle and related to its inner structure. Results concerning the concept of operational theory and its application to the electromagnetic and gravitational field theories, as well as to the quantum mechanics are given in appendixes.
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arxiv:physics/9912040
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The profile of a Bennett hole induced by laser field in ionic distribution in collisional plasma is calculated. Influence of Chandrasekhar's dependence of coefficients of velocity space transport on the profile is included into the calculation for the first time. It is found that the hole narrows down as the field detuning frequency increases. Physical cause of the effect is the falling dependence of Coulomb collision frequency on the ionic velocity. Estimations show that the effect is quite observable under conditions of high-current gas-discharge plasma.
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arxiv:plasm-ph/9503002
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We study certain family of finite-dimensional modules over the Yangian $Y(gl_N)$. The algebra $Y(gl_N)$ comes equipped with a distinguished maximal commutative subalgebra $A(gl_n)$ generated by the centres of all algebras in the chain $Y(gl_1)\subset Y(gl_2)\subset...\subset Y(gl_N)$. We study the finite-dimensional $Y(gl_N)$-modules with a semisimple action of the subalgebra $A(gl_N)$. We call these modules tame. We provide a characterization of irreducible tame modules in terms of their Drinfeld polynomials. We prove that every irreducible tame module splits into a tensor product of modules corresponding to the skew Young diagrams and some one-dimensional module. The eigenbases of $A(gl_N)$ in irreducible tame modules are called Gelfand-Zetlin bases. We provide explicit formulas for the action of the Drinfeld generators of the algebra $Y(gl_N)$ on the vectors of Gelfand-Zetlin bases.
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arxiv:q-alg/9502008
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We build the $q=-1$ defomation of plane on a product of two copies of algebras of functions on the plane. This algebra constains a subalgebra of functions on the plane. We present general scheme (which could be used as well to construct quaternion from pairs of complex numbers) and we use it to derive differential structures, metric and discuss sample field theoretical models.
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arxiv:q-alg/9503007
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The paper is devoted to the Poisson brackets compatible with multiplication in associative algebras. These brackets are shown to be quadratic and their relations with the classical Yang--Baxter equation are revealed. The paper also contains a description of Poisson Lie structures on Lie groups whose Lie algebras are adjacent to an associative structure.
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arxiv:q-alg/9503019
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We consider how a vertex operator algebra can be extended to an abelian intertwining algebra by a family of weak twisted modules which are {\em simple currents} associated with semisimple weight one primary vectors. In the case that the extension is again a vertex operator algebra, the rationality of the extended algebra is discussed. These results are applied to affine Kac-Moody algebras in order to construct all the simple currents explicitly (except for $E_8$) and to get various extensions of the vertex operator algebras associated with integrable representations.
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arxiv:q-alg/9504008
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A $q$-analogue of the multiple gamma functions is introduced, and is shown to satisfy the generalized Bohr-Morellup theorem. Furthermore we give some expressions of these function.
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arxiv:q-alg/9505013
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The wave functions of the Calogero-Sutherland model are known to be expressible in terms of Jack polynomials. A formula which allows to obtain the wave functions of the excited states by acting with a string of creation operators on the wave function of the ground state is presented and derived. The creation operators that enter in this formula of Rodrigues-type for the Jack polynomials involve Dunkl operators.
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arxiv:q-alg/9509003
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The Gauss decomposition of quantum groups and supergroups are considered. The main attention is paid to the R-matrix formulation of the Gauss decomposition and its properties as well as its relation to the contraction procedure. Duality aspects of the Gauss decomposition are also touched. For clarity of exposition a few simple examples are considered in some details.
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arxiv:q-alg/9511004
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Generators of multiparameter deformations $U_{q;s_1,s_2,...,s_{n-1}}(gl_n)$ of the universal enveloping algebra $U(gl_n)$ are realized bilinearly by means of appropriately generalized form of anyonic oscillators (AOs). This modification takes into account the parameters $s_1,...,s_{n-1}$ and yields usual AOs when all the $s_i$ are set equal to unity.
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arxiv:q-alg/9511017
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We check The Vaisman condition of geometric quantization for R-matrix type Poisson pencil on a coadjoint orbit of a compact Lie group. It is shown that this condition isn't satisfied.
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arxiv:q-alg/9512021
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In this paper we continue with the program to explore the topography of the space of W-type algebras. In the present case, the starting point is the work of Khesin, Lyubashenko and Roger on the algebra of q-deformed pseudodifferential symbols and their associated integrable hierarchies. The analysis goes on by studying the associated hamiltonian structures for which compact expressions are found. The fundamental Poisson brackets yield q-deformations of W_{KP} and related W-type algebras which, in specific cases, coincide with the ones constructed by Frenkel and Reshetikhin. The construction underlies a continuous correspondence between the hamiltonian structures of the Toda lattice and the KP hierarchies.
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arxiv:q-alg/9512025
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The bicovariant differential calculus on the three-dimensional Kappa-Poincar'e group and the corresponding Lie-algebra structure are described. The equivalence of this Lie-algebra structure and the three-dimensional $\kappa$-Poincar\'e algebra is proved.
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arxiv:q-alg/9602004
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This is an extension of quantum spinor construction of $U_q(\hat {\frak gl}(n))$. We define quantum affine Clifford algebras based on the tensor category and the solutions of q-KZ equations, and construct quantum spinor representations of $U_q(\hat{\frak o}(N))$.
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arxiv:q-alg/9602021
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Let $V_1 \otimes V_2$ be a tensor product of VOAs. Using Zhu theory we discuss the theory of representations of V (associative algebra, modules and fusion rules). We prove that this theory is more or less the same as representation theory of tensor product of the associative algebras.
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arxiv:q-alg/9602026
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The ``classical BRST construction'' as developed by Batalin-Fradkin-Vilkovisky is a homological construction for the reduction of the Poisson algebra $P = C^\infty (W)$ of smooth functions on a Poisson manifold $W$ by the ideal $I$ of functions which vanish on a constraint locus. This ideal is called first class if $I$ is closed under the Poisson bracket; geometers refer to the constraint locus as coisotropic. The physicists' model is crucially a differential Poisson algebra extension of a Poisson algebra $P$; its differential contains a piece which reinvented the Koszul complex for the ideal $I$ and a piece which looks like the Cartan-Chevalley-Eilenberg differential. The present paper is concerned purely with the homological (Poisson) algebraic structures, using the notion of ``model'' from rational homotopy theory and the techniques of homological perturbation theory to establish some of the basic results explaining the mathematical existence of the classical BRST-BFV construction. Although the usual treatment of BFV is basis dependent (individual constraints) and nominally finite dimensional, I take care to avoid assumptions of finite dimensionality and work more invariantly in terms of the ideal. In particular, the techniques are applied to the `irregular' case (the ideal is not generated by a regular sequence of constraints), although the geometric interpretation is less complete.
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arxiv:q-alg/9603021
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A systematic study of the representation theory of double affine Hecke algebras and related harmonic analysis is started in this paper. Continuing the previous papers we use the technique of intertwining operators to create Macdonald polynomials, estimate their denominators, generalize the classical representations of p-adic affine Hecke algebras in the spaces of functions on affine Weyl groups, and to find out when induced representations are irreducible and co-spherical. The connection with recent results by Sahi and Knop on the integrality of the Macdonald polynomials is established.
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arxiv:q-alg/9605014
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We study some properties of the Askey-Wilson polynomials (AWP) when q is a primitive N-th root of unity. For general four-parameter AWP, zeros of the N-th polynomial and the orthogonality measure are found explicitly. Special subclasses of the AWP, e.g., the continuous q-Jacobi and big q-Jacobi polynomials, are considered in detail. A set of discrete weight functions positive on a real interval is described. Some new trigonometric identities related to the AWP are obtained. Normalization conditions of some polynomials are expressed in terms of the Gauss sums.
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arxiv:q-alg/9605034
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The interpretation of the Meixner-Pollaczek, Meixner and Laguerre polynomials as overlap coefficients in the positive discrete series representations of the Lie algebra su(1,1) and the Clebsch-Gordan decomposition leads to generalisations of the convolution identities for these polynomials. Using the Racah coefficients convolution identities for continuous Hahn, Hahn and Jacobi polynomials are obtained. From the quantised universal enveloping algebra for su(1,1) convolution identities for the Al-Salam and Chihara polynomials and the Askey-Wilson polynomials are derived by using the Clebsch-Gordan and Racah coefficients. For the quantised universal enveloping algebra for su(2) q-Racah polynomials are interpreted as Clebsch-Gordan coefficients, and the linearisation coefficients for a two-parameter family of Askey-Wilson polynomials are derived.
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arxiv:q-alg/9607010
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For the current realization of the affine quantum groups, a simple comultiplication for the quantum current operators was given by Drinfeld. With this comultiplication, we study the zeros and poles of the quantum current operators and present a condition of integrability on the quantum current of $U_q\left(\hat{\frak sl}(2)\right)$, which is a deformation of the corresponding condition for $\hat{\frak sl}(2)$. We also present the results about the zeros and poles of the quantum current operators of $U_q\left(\hat{\frak sl}(n)\right)$.
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arxiv:q-alg/9608001
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In this article we propose a new and so-called holomorphic deformation scheme for locally convex algebras and Hopf algebras. Essentially we regard converging power series expansion of a deformed product on a locally convex algebra, thus giving the means to actually insert complex values for the deformation parameter. Moreover we establish a topological duality theory for locally convex Hopf algebras. Examples coming from the theory of quantum groups are reconsidered within our holomorphic deformation scheme and topological duality theory. It is shown that all the standard quantum groups comprise holomorphic deformations. Furthermore we show that quantizing the function algebra of a (Poisson) Lie group and quantizing its universal enveloping algebra are topologically dual procedures indeed. Thus holomorphic deformation theory seems to be the appropriate language in which to describe quantum groups as deformed Lie groups or Lie algebras.
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arxiv:q-alg/9612015
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The generators $(J_{\pm}, J_0)$ of the algebra $U_q(sl(2))$ is our starting point. An invertible nonlinear map involving, apart from q, a second arbitrary complex parameter h, defines a triplet $({\hat X},{\hat Y},{\hat H})$. The latter set forms a closed algebra under commutation relations. The nonlinear algebra $U_{q,h}(sl(2))$, thus generated, has two different limits. For $q \to 1$, the Jordanian h-deformation $U_{h}(sl(2))$ is obtained. For $h \to 0$, the q-deformed algebra $U_{q}(sl(2))$ is reproduced. From the nonlinear map, the irreducible representations of the doubly-deformed algebra $U_{q,h}(sl(2))$ may be directly and explicitly obtained form the known representations of the algebra $U_q(sl(2))$. Here we consider only generic values of q.
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arxiv:q-alg/9612028
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Let $P(N,V)$ denote the vector space of polynomials of maximal degree less than or equal to $N$ in $V$ independent variables. This space is preserved by the enveloping algebra generated by a set of linear, differential operators representing the Lie algebra $gl(V+1)$. We establish the counterpart of this property for the vector space $P(M,V) \oplus P(N,V)$ for any values of the integers $M,N,V$. We show that the operators preserving $P(M,V) \oplus P(N,V)$ generate an abstract superalgebra (non linear if $\Delta=\mid M-N\mid\geq 2$). A family of algebras is also constructed, extending this particular algebra by $\Delta -1$ arbitrary complex parameters.
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arxiv:q-alg/9701016
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This paper is a continuation of "Quantization of Lie bialgebras, I" (q-alg/9606005). We show that the quantization procedure defined in "Quantization of Lie bialgebras, I" is given by universal acyclic formulas and defines a functor from the category of Lie bialgebras to the category of quantized universal enveloping algebras. We also show that this functor defines an equivalence between the category of Lie bialgebras over k[[h]] and the category quantized universal enveloping (QUE) algebras.
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arxiv:q-alg/9701038
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Recently Varagnolo and Vasserot established that the q-deformed Fock spaces due to Hayashi, and Kashiwara, Miwa and Stern, admit actions of the quantum toroidal algebra $U_q(sl_n,tor)$ (n > 2) with the level (0,1). In the present article we propose a more detailed proof of this fact then the one given by Varagnolo and Vasserot. The proof is based on certain non-trivial properties of Cherednik's commuting difference operators. The quantum toroidal action on the Fock space depends on a certain parameter. We find that with a specific choice of this parameter the action on the Fock spaces gives rise to the toroidal action on irreducible level-1 highest weight modules of the affine quantum algebra $U_q(\hat{sl}_n)$. Similarly, by a specific choice of the parameter, the level (1,0) vertex representation of the quantum toroidal algebra gives rise to a $U_q(sl_n,tor)$-module structure on irreducible level-1 highest weight $U_q(\hat{sl}_n)$-modules.
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arxiv:q-alg/9702024
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We introduce a new class of 2-cocycles defined explicitly on the generators of certain multiparameter standard quantum groups. These allow us, through the process of twisting the familiar standard quantum groups, to generate new as well as previously known examples of non-standard quantum groups. In particular we are able to construct generalisations of both the Cremmer-Gervais deformation of SL(3) and the so called esoteric quantum groups of Fronsdal and Galindo in an explicit and straightforward manner.
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arxiv:q-alg/9702028
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Using the isomorphism between highest weight U_q(sl_2)-modules and homologies of certain local systems on the configuration spaces, constructed by Varchenko, we give a geometric construction of the dual of the Lusztig's canonical basis in a tensor product of irreducible finite-dimensional U_q(sl_2)-modules.
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arxiv:q-alg/9703007
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Following the introduction of the invariant distance on the non-commutative C-algebra of the quantum group SU_q(2), the Green function and the Kernel on the q-homogeneous space M=SU(2)_q/U(1) are derived. A path integration is formulated. Green function for the free massive scalar field on the non-commutative Einstein space R^1xM is presented.
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arxiv:q-alg/9703032
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With slight modifications in the zero modes contributions, the positive and negative screening currents for the quantum deformed W-algebra W_{q,p}(g) can be put together to form a single algebra which can be regarded as an elliptic deformation of the universal enveloping algebra of \hat{g}, where g is any classical simply-laced Lie algebra.
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arxiv:q-alg/9704018
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A two-parametric non-standard (Jordanian) deformation of the Lie algebra $gl(2)$ is constructed, and then, exploited to obtain a new, triangular R-matrix solution of the coloured Yang-Baxter equation. The corresponding coloured quantum group is presented explicitly.
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arxiv:q-alg/9705027
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We give an analogue of the Hom functor and prove a generalized form of the nuclear democracy theorem of Tsuchiya and Kanie by using a notion of tensor product for two modules for a vertex operator algebra.
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arxiv:q-alg/9706012
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A rational Ansatz is proposed for the generating function $\sum_{j,k} \beta_{2j+k,2j}x^j y^k$, where $\beta_{m,u}$ is the number of primitive chinese character diagrams with $u$ univalent and $2m-u$ trivalent vertices. For $P_m:=\sum_{u\ge2}\beta_{m,u}$, the conjecture leads to the sequence $$1,1,1,2,3,5,8,12,18,27,39,55,\underline{78,108,150,207,284,388,532,726}$$ for primitive chord diagrams of degrees $m\le20$, with predictions underlined. The asymptotic behaviour $\lim_{m\to\infty}P_m/r^m= 1.06260548918755$ results, with $r=1.38027756909761$ solving $r^4=r^3+1$. Vassiliev invariants of knots are then enumerated by $$0,1,1,3,4,9,14,27,44, 80,132,232,\underline{384,659,1095,1851,3065,5128,8461,14031}$$ and Vassiliev invariants of framed knots by $$1,2,3,6,10,19,33,60,104,184,316, 548,\underline{932,1591,2686,4537,7602,12730,21191,35222}$$ These conjectures are motivated by successful enumerations of irreducible Euler sums. Predictions for $\beta_{15,10}$, $\beta_{16,12}$ and $\beta_{19,16}$ suggest that the action of sl and osp Lie algebras, on baguette diagrams with ladder insertions, fails to detect an invariant in each case.
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arxiv:q-alg/9709031
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We study quantized enveloping algebras called twisted Yangians. They are analogues of the Yangian Y(gl(N)) for the classical Lie algebras of B, C, and D series. The twisted Yangians are subalgebras in Y(gl(N)) and coideals with respect to the coproduct in Y(gl(N)). We give a complete description of their finite-dimensional irreducible representations. Every such representation is highest weight and we give necessary and sufficient conditions for an irreducible highest weight representation to be finite-dimensional. The result is analogous to Drinfeld's theorem for the ordinary Yangians. Its detailed proof for the A series is also reproduced. For the simplest twisted Yangians we construct an explicit realization for each finite-dimensional irreducible representation in tensor products of representations of the corresponding Lie algebras.
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arxiv:q-alg/9711022
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The Poincare duality of classical cohomology and the extension of this duality to quantum cohomology endows these rings with the structure of a Frobenius algebra. Any such algebra possesses a canonical ``characteristic element;'' in the classical case this is the Euler class, and in the quantum case this is a deformation of the classical Euler class which we call the ``quantum Euler class.'' We prove that the characteristic element of a Frobenius algebra A is a unit if and only if A is semisimple, and then apply this result to the cases of the quantum cohomology of the finite complex Grassmannians, and to the quantum cohomology of hypersurfaces. In addition we show that, in the case of the Grassmannians, the [quantum] Euler class equals, as [quantum] cohomology element and up to sign, the determinant of the Hessian of the [quantum] Landau-Ginzbug potential.
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arxiv:q-alg/9712025
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We discuss the consequences of the possibility that Vassiliev invariants do not detect knot invertibility as well as the fact that quantum Lie group invariants are known not to do so. On the other hand, finite group invariants, such as the set of homomorphisms from the knot group to M_11, can detect knot invertibility. For many natural classes of knot invariants, including Vassiliev invariants and quantum Lie group invariants, we can conclude that the invariants either distinguish all oriented knots, or there exist prime, unoriented knots which they do not distinguish.
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arxiv:q-alg/9712048
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We study a recent model for calcium signal transduction. This model displays spiking, bursting and chaotic oscillations in accordance with experimental results. We calculate bifurcation diagrams and study the bursting behaviour in detail. This behaviour is classified according to the dynamics of separated slow and fast subsystems. It is shown to be of the Fold-Hopf type, a type which was previously only described in the context of neuronal systems, but not in the context of signal transduction in the cell.
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arxiv:q-bio/0310018
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Two rate code models -- a reconstruction network model and a control model -- of the hippocampal-entorhinal loop are merged. The hippocampal-entorhinal loop plays a double role in the unified model, it is part of a reconstruction network and a controller, too. This double role turns the bottom-up information flow into top-down control like signals. The role of bottom-up filtering is information maximization, noise filtering, temporal integration and prediction, whereas the role of top-down filtering is emphasizing, i.e., highlighting or `paving of the way' as well as context based pattern completion. In the joined model, the control task is performed by cortical areas, whereas reconstruction networks can be found between cortical areas. While the controller is highly non-linear, the reconstruction network is an almost linear architecture, which is optimized for noise estimation and noise filtering. A conjecture of the reconstruction network model -- that the long-term memory of the visual stream is the linear feedback connections between neocortical areas -- is reinforced by the joined model. Falsifying predictions are presented; some of them have recent experimental support. Connections to attention and to awareness are made.
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arxiv:q-bio/0311030
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We reexamine the generalized cognitive homunculus, an organism's internalized image of its physiological, psychological, and social state, which, when properly adjusted, can quickly detect subtle deviations from a reference configuration. We particularly seek to extend the treatment beyond 'language-of-thought' systems modeled as ergodic information sources. Such extension would generate an exceedingly rich response repertoire, not limited by fixed patterns of grammar and syntax. Rather, these would themselves be tunable according to the changing short-term contextual demands faced by the organism, possibly providing significant long-term adaptive advantage.
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arxiv:q-bio/0312003
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We have computed the widely neglected first-order interaction between neutral atoms. At interatomic separations typical of condensed media, it is nearly equal to the 1/r^6 second-order London energy inferred from interactions in gasses. Our results, without the exchange forces that lead to covalent bonding, suggest that the quality of non-bonding attraction between neutral atoms of molecules in condensed media differs from the 1/r^6 form usually ascribed to it. If we add first-order and all second-order terms, we obtain energies nearly five times the 1/r^6 London energies which dominate only at the atomic separations found in gasses. For computation, we propose a practical, accurate form of energy to replace the qualitatively inaccurate Lennard-Jones and harmonic forms casually assumed to hold at the interatomic separations found in condensed media.
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arxiv:q-bio/0312005
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We propose a two-dimensional model for a complete description of the dynamics of molecular motors, including both the processive movement along track filaments and the dissociation from the filaments. The theoretical results on the distributions of the run length and dwell time at a given ATP concentration, the dependences of mean run length, mean dwell time and mean velocity on ATP concentration and load are in good agreement with the previous experimental results.
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arxiv:q-bio/0312040
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For many applications one wishes to decide whether a certain set of numbers originates from an equiprobability distribution or whether they are unequally distributed. Distributions of relative frequencies may deviate significantly from the corresponding probability distributions due to finite sample effects. Hence, it is not trivial to discriminate between an equiprobability distribution and non-equally distributed probabilities when knowing only frequencies. Based on analytical results we provide a software tool which allows to decide whether data correspond to an equiprobability distribution. The tool is available at http://bioinf.charite.de/equifreq/. Its application is demonstrated for the distribution of point mutations in coding genes.
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arxiv:q-bio/0401041
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Recognition and binding of specific sites on DNA by proteins is central for many cellular functions such as transcription, replication, and recombination. In the process of recognition, a protein rapidly searches for its specific site on a long DNA molecule and then strongly binds this site. Here we aim to find a mechanism that can provide both a fast search (1-10 sec) and high stability of the specific protein-DNA complex ($K_d=10^{-15}-10^{-8}$ M). Earlier studies have suggested that rapid search involves the sliding of a protein along the DNA. Here we consider sliding as a one-dimensional (1D) diffusion in a sequence-dependent rough energy landscape. We demonstrate that, in spite of the landscape's roughness, rapid search can be achieved if 1D sliding is accompanied by 3D diffusion. We estimate the range of the specific and non-specific DNA-binding energy required for rapid search and suggest experiments that can test our mechanism. We show that optimal search requires a protein to spend half of time sliding along the DNA and half diffusing in 3D. We also establish that, paradoxically, realistic energy functions cannot provide both rapid search and strong binding of a rigid protein. To reconcile these two fundamental requirements we propose a search-and-fold mechanism that involves the coupling of protein binding and partial protein folding. Proposed mechanism has several important biological implications for search in the presence of other proteins and nucleosomes, simultaneous search by several proteins etc. Proposed mechanism also provides a new framework for interpretation of experimental and structural data on protein-DNA interactions.
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arxiv:q-bio/0402005
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Viral kinetics have been extensively studied in the past through the use of spatially homogeneous ordinary differential equations describing the time evolution of the diseased state. However, spatial characteristics such as localized populations of dead cells might adversely affect the spread of infection, similar to the manner in which a counter-fire can stop a forest fire from spreading. In order to investigate the influence of spatial heterogeneities on viral spread, a simple 2-D cellular automaton (CA) model of a viral infection has been developed. In this initial phase of the investigation, the CA model is validated against clinical immunological data for uncomplicated influenza A infections. Our results will be shown and discussed.
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arxiv:q-bio/0402012
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The purpose of research was to check up the influence of decrease of nonequality of ventilating (after bronchodilator (berotec) inhalation (BI)) on the magnitude of dynamic compliance of lungs (Cdyn) at asthma patients with ventilating infringements. Methods and materials: 20 patients (with 2 and 3 degrees of ventilating infringements (VC<73%, FEV1<51%, MVV<56%), without restrictive disease of lungs, suffering from bronchial asthma were studied before and after BI by plotting volume, rate flow, against the transpulmonare pressure. About the change of nonequality of ventilating we consider by the change after BI of Cdyn, Cdyn at once after flow interruption (Cdyn1), tissue resistance at inhalation (Rti in) and exhalation (Rti ex), parameters of ventilating and general parameters of respiratory mechanics. Results: the parameters of ventilating were improved (P < 0,05). General parameters of respiratory mechanics also improved. Rti in and Rti ex are made 0,48+0,16; 1,05+0,25 kPa/l/s before BI and decreased 0,09+0,04; 0,28+0,09 kPa/l/s after BI (P < 0,05; P < 0,05). But Cdyn and Cdyn1 are not changed after BI. Conclusions: 1. The decrease of ventilation nonequality and tissue friction after BI do not influence on the initially reduced dynamic compliance of lungs at asthma patients without any restrictive diseases of lungs. 2. The cause of not increasing of dynamic compliance after BI probably due by changes in elastic component of parenchyma of lungs, insensitive to berotec.
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arxiv:q-bio/0402025
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Accurate demographic functions help scientists define and understand longevity. We summarize a new demographic model, the Weon model, and show the application to the demographic data for Switzerland (1876-2002). Particularly, the Weon model simply defines the maximum longevity, which is induced in nature by the mortality dynamics. In this study, we reconsider the definition of the maximum longevity and the effectiveness for longevity by the combined effect of the survival and mortality functions. The results suggest that the mortality function should be zero at the maximum longevity, since the density function is zero but the survival function is not zero. Furthermore, the effectiveness for longevity can be maximized at the characteristic life by the complementarity between the survival and mortality functions, which suggests that there may be two parts of rectangularization for longevity. The historical trends for Switzerland (1876-2002) implies that there may be a fundamental limiting force to restrict the increase of the effectiveness. As a result, it seems that the density function is essential to define and understand the mortality dynamics, the maximum longevity, the effectiveness for longevity, the paradigm of rectangularization and the historical trends of the effectiveness by the complementarity between the survival and mortality functions.
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arxiv:q-bio/0403017
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We first review how to determine the rate of vibrational energy relaxation (VER) using perturbation theory. We then apply those theoretical results to the problem of VER of a CD stretching mode in the protein cytochrome c. We model cytochrome c in vacuum as a normal mode system with the lowest-order anharmonic coupling elements. We find that, for the ``lifetime'' width parameter $\gamma=3 \sim 30$ cm$^{-1}$, the VER time is $0.2 \sim 0.3$ ps, which agrees rather well with the previous classical calculation using the quantum correction factor method, and is consistent with spectroscopic experiments by Romesberg's group. We decompose the VER rate into separate contributions from two modes, and find that the most significant contribution, which depends on the ``lifetime'' width parameter, comes from those modes most resonant with the CD vibrational mode.
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arxiv:q-bio/0403019
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The PHASE software package allows phylogenetic tree construction with a number of evolutionary models designed specifically for use with RNA sequences that have conserved secondary structure. Evolution in the paired regions of RNAs occurs via compensatory substitutions, hence changes on either side of a pair are correlated. Accounting for this correlation is important for phylogenetic inference because it affects the likelihood calculation. In the present study we use the complete set of tRNA and rRNA sequences from 69 complete mammalian mitochondrial genomes. The likelihood calculation uses two evolutionary models simultaneously for different parts of the sequence: a paired-site model for the paired sites and a single-site model for the unpaired sites. We use Bayesian phylogenetic methods and a Markov chain Monte Carlo algorithm is used to obtain the most probable trees and posterior probabilities of clades. The results are well resolved for almost all the important branches on the mammalian tree. They support the arrangement of mammalian orders within the four supra-ordinal clades that have been identified by studies of much larger data sets mainly comprising nuclear genes. Groups such as the hedgehogs and the murid rodents, which have been problematic in previous studies with mitochondrial proteins, appear in their expected position with the other members of their order. Our choice of genes and evolutionary model appears to be more reliable and less subject to biases caused by variation in base composition than previous studies with mitochondrial genomes.
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arxiv:q-bio/0404031
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Within a case study on the protein-protein interaction network (PIN) of Drosophila melanogaster we investigate the relation between the network's spectral properties and its structural features such as the prevalence of specific subgraphs or duplicate nodes as a result of its evolutionary history. The discrete part of the spectral density shows fingerprints of the PIN's topological features including a preference for loop structures. Duplicate nodes are another prominent feature of PINs and we discuss their representation in the PIN's spectrum as well as their biological implications.
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arxiv:q-bio/0405021
|
Novel techniques are currently being developed and established for the accurate chemical analysis and detection of single cancer cells, single embryos and single seeds by Fourier Transform Near Infrared (FT-NIR) Microspectroscopy, Fourier Transform Infrared (FT-IR), Fluorescence and High-Resolution NMR (HR-NMR). The first FT-NIR chemical images of biological systems approaching 1micron resolution are here reported. 400 and 500 MHz, H-1 NMR analyses were carried out that allowed the selection of mutagenized embryos. Detailed chemical analyses are being demonstrated to be also possible by FT-NIR Chemical Imaging/ Microspectroscopy of single cancer cells. FT-NIR Microspectroscopy and Chemical Imaging are also shown to be potentially important in Functional Genomics and Proteomics research through the rapid and accurate detection of high-content microarrays (HCMA). Multi-photon (MP), pulsed femtosecond laser NIR Fluorescence Excitation techniques were shown to be capable of Single Molecule Detection (SMD. Thus, MP NIR excitation for Fluorescence Correlation Spectroscopy (FCS) allowed not only single molecule detection, but also molecular dynamics observations and high resolution, submicron imaging of sub-femtoliter volumes inside living cells with 0.25 micron spatial resolution, in both normal and cancer cells, as well as neoplastic tissues. These novel, ultra-sensitive and rapid FT-NIR/FCS analyses have, therefore, substantial potential for numerous applications in important research areas, such as: medicine, medical/cancer research, pharmacology, agricultural biotechnology, food safety, as well as clinical diagnosis of viral diseases and cancers.
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arxiv:q-bio/0407006
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The complexity of a neuronal cell shape is known to be related to its function. Specifically, among other indicators, a decreased complexity in the dendritic trees of cortical pyramidal neurons has been associated with mental retardation. In this paper we develop a procedure to address the characterization of morphological changes induced in cultured neurons by over-expressing a gene involved in mental retardation. Measures associated with the multiscale connectivity, an additive image functional, are found to give a reasonable separation criterion between two categories of cells. One category consists of a control group and two transfected groups of neurons, and the other, a class of cat ganglionary cells. The reported framework also identified a trend towards lower complexity in one of the transfected groups. Such results establish the suggested measures as an effective descriptors of cell shape.
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arxiv:q-bio/0408004
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As subjects perceive the sensory world, different stimuli elicit a number of neural representations. Here, a subjective distance between stimuli is defined, measuring the degree of similarity between the underlying representations. As an example, the subjective distance between different locations in space is calculated from the activity of rodent hippocampal place cells, and lateral septal cells. Such a distance is compared to the real distance, between locations. As the number of sampled neurons increases, the subjective distance shows a tendency to resemble the metrics of real space.
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arxiv:q-bio/0408008
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Being HIV-1-PR an essential enzyme in the viral life cycle, its inhibition can control AIDS. Because the folding of single domain proteins, like HIV-1-PR is controlled by local elementary structures (LES, folding units stabilized by strongly interacting, highly conserved amino acids) which have evolved over myriads of generations to recognize and strongly attract each other so as to make the protein fold fast, we suggest a novel type of HIV-1-PR inhibitors which interfere with the folding of the protein: short peptides displaying the same amino acid sequence of that of LES. Theoretical and experimental evidence for the specificity and efficiency of such inhibitors are presented.
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arxiv:q-bio/0408013
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Small Ubiquitin-related modifier (SUMO) proteins are widely expressed in eukaryotic cells, which are reversibly coupled to their substrates by motif recognition, called sumoylation. Two interesting questions are 1) how many potential SUMO substrates may be included in mammalian proteomes, such as human and mouse, 2) and given a SUMO substrate, can we recognize its sumoylation sites? To answer these two questions, previous prediction systems of SUMO substrates mainly adopted the pattern recognition methods, which could get high sensitivity with relatively too many potential false positives. So we use phylogenetic conservation between mouse and human to reduce the number of potential false positives.
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arxiv:q-bio/0409011
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