bluuebunny/crossref_metadata_2025 huggingface dataset:
A new baphetid (stem tetrapod) from the Upper Carboniferous of Tyne and Wear, U.K., and the evolution of the tetrapod occiput
Authors: Clack J A
Published: May 2003

A new genus and species of baphetid, Kyrinion martilli, is described from the Westphalian A (Upper Carboniferous) of Tyne and Wear, England. The skull, braincase, and partial lower jaws are preserved in a nodule of iron-rich seat-earth, in an almost uncrushed state. The occiput and both stapes are in place. The palate and braincase are united by a continuous sheet of denticulated pterygoid and parasphenoid eliminating the interpterygoid vacuities completely, and the parasphenoid bounds deep parasphenoidal tubera; the marginal palatal bones, pterygoid, and dentary are united by interdigitated sutures, rendering the whole skull akinetic. The orbits are approximately triangular, without the "pinching in" that defines an antorbital embayment in other baphetids. The maxilla has a very narrow exposure beneath and posterior to the orbit, and though it and the lacrimal lack lateral line grooves, there is a short stretch on the quadratojugal. Unlike Megalocephalus, the lower jaw symphysis is relatively simple and does not bear a "brassicate" structure and the parasymphysial plate lacks teeth. The stapes is broad and flat distally, with its distal end lying against the palatal bones as in other early tetrapods, but it is difficult to envisage a structural role for this element as suggested by recent hypotheses. The basi- and exoccipitals co-ossified as in some specimens of Greererpeton and Acanthostega, but unlike the latter, the condyle is almost fully ossified. The exoccipitals do not contact the skull roof as they do in temnospondyls, but fully ossified paroccipital processes suture with the tabulars, a feature suggested as synapomorphous for baphetids plus temnospondyls. The specimen also preserves a rib, possibly but not certainly cervical, and an atlas arch. The proatlantes of Loxomma are descibed and figured.
A review of nonmarine turtles from the Late Cretaceous of Alberta
Authors: Brinkman Donald B
Published: May 2003

The Late Cretaceous of Alberta preserves one of the most complete records of fossil turtles within a single geographic area in North America. The Cenomanian Dunvegan Formation contains the earliest record of the family Trionychidae in North America. The Santonian Milk River Formation contains a minimum of ten taxa with Adocus, a small trionychid, and a member of the Solemydidae being the most abundant. Diversity remains high in the mid-Campanian Judith River Group. The solemyidid last occurs in the basal beds of the Judith River Group. A member of the Macrobaenidae first occurs in the Dinosaur Park Formation, the uppermost formation in the Judith River Group. Turtles diversity is low in the late Campanian lower Horseshoe Canyon Formation, and they are absent in the early Maastrichtian upper Horseshoe Canyon Formation. Diversity increases in the late Maastrichtian Scollard Formation, although it is much less than in the contemporaneous Hell Creek Formation of Montana. Two of the taxa present in the Scollard Formation, Compsemys and Plastomenus, occur in late Campanian or early Maastrichtian formations in more southerly areas of North America. The changes in turtle diversity through the Campanian and Maastrichtian are interpreted as a result of shifts in a latitudinal turtle diversity gradient resulting from changes in climate. Based on this interpretation a decrease in temperature from the mid-Campanian to early Maastrichtian, followed by a rapid increase at the beginning of the late Maastrichtian is supported.
Early rhinocerotids (Mammalia: Perissodactyla) from South Asia and a review of the Holarctic Paleogene rhinocerotid record
Authors: Antoine Pierre-Olivier , Ducrocq Stéphane , Marivaux Laurent , Chaimanee Yaowalak , Crochet Jean-Yves , Jaeger Jean-Jacques , Welcomme Jean-Loup
Published: May 2003

The earliest rhinocerotids from South Asia are identified on the basis of few dental remains originating from the Late Eocene of Thailand (Wai Lek mine, Krabi Basin) and the Early Oligocene of Pakistan (Paali nala C2, Bugti Hills). Once synthesized, the Holarctic Paleogene rhinocerotid record points out a westward diachronism of rhinocerotid First Appearance Data, from North America to Europe via Asia, throughout mid-Cenozoic times. The faunal similarity among mammal localities from the Late Eocene and Early Oligocene of peninsular Thailand, southern China, and Pakistan suggests the existence of a single South Asian paleoprovince during this interval and the persistence of a tropicalsubtropical climate. Substantial faunal changes recorded in eastern Balochistan reveal a significant climatic deterioration from the middle part of the Oligocene. Neither provinciality nor endemism is noticeable for rhinocerotoid taxa recognized in the Oligocene of the Indian subcontinent: neither the Himalayas nor the Tibet Plateau was a paleogeographic barrier for large mammals during this interval.
LINDSTRÖM QUANTIFIERS AND LEAF LANGUAGE DEFINABILITY
Authors: BURTSCHICK HANS-JÖRG , VOLLMER HERIBERT
Published: May 2003

We introduce second-order Lindström quantifiers and examine analogies to the concept of leaf language definability. The quantifier structure in a second-order sentence defining a language and the quantifier structure in a first-order sentence characterizing the appropriate leaf language correspond to one another. Under some assumptions, leaf language definability and definability with second-order Lindström quantifiers may be seen as equivalent. Along the way we tighten the best up to now known leaf language characterization of the classes of the polynomial time hierarchy and give a new model-theoretic characterization of PSPACE.
Nonlinear System Identification Using a Neo Fuzzy Neuron Algorithm: Electrical Drive Application
Authors: LANDIM RÉGIS P. , MENEZES BENJAMIM R. DE , SILVA SELÊNIO R. , CAMINHAS WALMIR M.
Published: May 2003

This work presents a Neo-Fuzzy-Neuron algorithm for the identification of nonlinear dynamic systems at the point of view of a rotor flux observer. The algorithm training is on-line, has low computational cost, does not require previous training and its convergence in one step is proved. The gradient descent method is used for its weights adjustment. Simulation and experimental results demonstrate the effetiveness of the algorithm for flux observer of induction motor drive system.
BLACK HOLE AND BRANE PRODUCTION IN TEV GRAVITY: A REVIEW
Authors: CAVAGLIÀ MARCO
Published: May 2003

In models with large extra dimensions, particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate nonperturbative gravitational objects such as black holes and branes. The formation and the subsequent decay of these super-Planckian objects would be detectable in particle colliders and high energy cosmic ray detectors, and have interesting implications in cosmology and astrophysics. In this paper we present a review of black hole and brane production in TeV-scale gravity.
EXCLUSIVE B MESON RARE DECAYS AND GENERAL RELATIONS OF FORM FACTORS IN EFFECTIVE FIELD THEORY OF HEAVY QUARKS
Authors: ZHONG M. , WU Y. L. , WANG W. Y.
Published: May 2003

B meson rare decays ([Formula: see text] and B → K* γ) are analyzed in the framework of effective field theory of heavy quarks. The semileptonic and penguin type form factors for these decays are calculated by using the light cone sum rules method at the leading order of 1/mQexpansion. Four exact relations between the two types of form factors are obtained at the leading order of 1/mQexpansion. In particular, the relations are found to hold for the whole momentum transfer region. We also investigate the validity of the relations resulting from the large energy effective theory based on the general relations obtained in the present approach. The branching ratios of the rare decays are presented and their potential importance for extracting the CKM matrix elements and probing new physics is emphasized.
DYONIC BLACK HOLES WITH STRING-LOOP CORRECTIONS
Authors: IOFA MIKHAIL Z.
Published: May 2003

In heterotic string theory compactified to four dimensions with N = 2 supersymmetry, string-loop corrections to the universal sector of the low-energy effective action are studied. Within the framework of N = 2 supersymmetric formulation of the theory, in the first order in string coupling constant, we solve the system of the loop-corrected Maxwell and Killing spinor equations. Taking as the input the tree-level dyonic black hole solution, we calculate string-loop corrections to the string tree-level metric and moduli of dyonic black hole.
MAGNETIC CHARGE, ANGULAR MOMENTUM AND NEGATIVE COSMOLOGICAL CONSTANT
Authors: VAN DER BIJ J. J. , RADU EUGEN
Published: May 2003

We argue that there are no axially symmetric rotating monopole solutions for a Yang–Mills–Higgs theory in flat space–time background. We construct axially symmetric Yang–Mills–Higgs solutions in the presence of a negative cosmological constant, carrying magnetic charge n and a nonvanishing electric charge. However, these solution are also nonrotating.
ULTRAHIGH ENERGY COSMIC RAYS: THE STATE OF THE ART BEFORE THE AUGER OBSERVATORY
Authors: ANCHORDOQUI LUIS , PAUL THOMAS , REUCROFT STEPHEN , SWAIN JOHN
Published: May 2003

In this review we discuss the important progress made in recent years towards understanding the experimental data on cosmic rays with energies ≳ 1019eV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition, and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the conjectured nearby cosmic ray sources. We then turn to theoretical notions of physics beyond the Standard Model where we consider both exotic primaries and exotic physical laws. Particular attention is given to the role that TeV-scale gravity could play in addressing the origin of the highest energy cosmic rays. In the final part of the review we discuss the potential of future cosmic ray experiments for the discovery of tiny black holes that should be produced in the earth's atmosphere if TeV-scale gravity is realized in Nature.
GAUGING BY SYMMETRIES
Authors: NETO J. ANANIAS , NEVES C. , OLIVEIRA W.
Published: May 2003

We propose a new procedure to embed second class systems by introducing Wess–Zumino (WZ) fields in order to unveil hidden symmetries existent in the models. This formalism is based on the direct imposition that the new Hamiltonian must be invariant by gauge-symmetry transformations. An interesting feature in this approach is the possibility to find a representation for the WZ fields in a convenient way, which leads to preserve the gauge symmetry in the original phase space. Consequently, the gauge-invariant Hamiltonian can be written only in terms of the original phase-space variables. In this situation, the WZ variables are only auxiliary tools that permit to reveal the hidden symmetries present in the original second class model. We apply this formalism to important physical models: the reduced-SU(2) Skyrme model, the Chern–Simons–Proca quantum mechanics and the chiral bosons field theory. In all these systems, the gauge-invariant Hamiltonians are derived in a very simple way.
FUZZY COMPLEX GRASSMANNIAN SPACES AND THEIR STAR PRODUCTS
Authors: DOLAN BRIAN P. , JAHN OLIVER
Published: May 2003

We derive an explicit expression for an associative star product on noncommutative versions of complex Grassmannian spaces, in particular for the case of complex two-planes. Our expression is in terms of a finite sum of derivatives. This generalizes previous results for complex projective spaces and gives a discrete approximation for the Grassmannians in terms of a noncommutative algebra, represented by matrix multiplication in a finite-dimensional matrix algebra. The matrices are restricted to have a dimension which is precisely determined by the harmonic expansion of functions on the commutative Grassmannian, truncated at a finite level. In the limit of infinite-dimensional matrices we recover the commutative algebra of functions on the complex Grassmannians.
PARTICLE PRODUCTION IN RHIC, THE pT-SPECTRA AND A NEW APPROACH
Authors: DE BHASKAR , BHATTACHARYYA S. , GUPTAROY P.
Published: May 2003

The RHIC measurements on the transverse momentum spectra of the main category of secondary particles produced in the Au + Au collisions were reported in the recent past. The combination of the phenomenological approaches we adopted provide a satisfactory, alternative framework for understanding and explaining the latest data-spurts on charged pions, kaons and the protons–antiprotons. The comparison of the performances by the contesting models on a select kind of secondary (π+) which belongs to the most abundant variety has also been made. The impact and implications of all these have also been spelt out in the end.
VANISHING OF THE BARE COUPLING IN FOUR DIMENSIONS
Authors: ELIAS V. , MCKEON D. G. C.
Published: May 2003

We examine two restructurings of the series relationship between the bare and renormalized coupling constant in dimensional regularization. In one of these restructurings, we are able to demonstrate via all-orders summation of leading and successive ∊ = 0 (dimensionality = 4) poles that the bare coupling vanishes in the dimension-4 limit.
DIFFRACTION ON ICOSAHEDRAL DANZER TILINGS
Authors: GARCÍA ESCUDERO JUAN , GARCÍA JAVIER GARCÍA
Published: May 2003

An interpretation of Icosahedral Danzer tilings in terms of algebraic substitutions is used in order to study the Fourier transform of suitable mass distributions. Numerical results are obtained for a mass distribution placed on vertex positions.
EQUIVALENT CIRCUIT MODEL OF Ca1-xYxTi1-xCoxO3 USING IMPEDANCE SPECTROSCOPY
Authors: KATARE RAJESH KUMAR , PANDEY LAKSHMAN , THAKUR O. P. , PARKASH OM , KUMAR DEVENDRA
Published: May 2003

Computer simulated complex immittance spectra of model equivalent circuits involving resistive and capacitive elements are calculated. A comparison of experimentally obtained complex immittance plots of the system Ca 1-x Y x Ti 1-x Co x O 3(x=0.05) with these simulated diagrams greatly facilitates the search for the most appropriate equivalent circuit representing the electrical properties of electronic ceramics.
GAUGE INVARIANT DRESSED HOLON AND SPINON IN DOPED CUPRATES
Authors: FENG SHIPING , MA TIANXING , QIN JIHONG
Published: May 2003

We develop a partial charge-spin separation fermion-spin theory implemented by the gauge invariant dressed holon and spinon. In this novel approach, the physical electron is decoupled as the gauge invariant dressed holon and spinon, with the dressed holon behaviors like a spinful fermion, and represents the charge degree of freedom together with the phase part of the spin degree of freedom, while the dressed spinon is a hard-core boson, and represents the amplitude part of the spin degree of freedom, then the electron single occupancy local constraint is satisfied. Within this approach, the charge transport and spin response of the underdoped cuprates is studied. It is shown that the charge transport is mainly governed by the scattering from the dressed holons due to the dressed spinon fluctuation, while the scattering from the dressed spinons due to the dressed holon fluctuation dominates the spin response.
DESIGN OF STABLE 3D RECURSIVE DIGITAL FILTERS USING 3-VARIABLE VERY STRICTLY HURWITZ POLYNOMIAL
Authors: EL-FEGHI I. , AHMADI M. , MILLER W. C. , SID-AHMED M. A. , RAMACHANDRAN V.
Published: May 2003

In this paper, methods for generating 3-variable Very Strictly Hurwitz Polynomials (VSHP's) are presented. It is shown that the derived 3-variable VSHP's could be used to design stable three-dimensional digital filters satisfying prescribed magnitude specifications.
2D ZERO-PHASE FIR FILTER DESIGN WITH NONUNIFORM FREQUENCY SAMPLING
Authors: RAMACHANDRAN V. , NINOV V.
Published: May 2003

In this paper, nonuniform frequency sampling techniques used in the design of two-dimensional zero-phase FIR filters are proposed and investigated. The design problem is treated as a bivariate interpolation problem with unevenly spaced data. The main idea is to select (find) sampling locations in the (ω1, ω2) frequency plane and corresponding sample values Hd(ω1k, ω2k) of the desired filter frequency response such that the designed filter performance is high. Although the filters designed with the proposed techniques are not optimal, the methods are conceptually simple and produce filters with high degree of shape regularity and approximation error comparable and sometimes even smaller than the "conventional" 2D FIR filter design methods.
LOW-POWER 2D MOTION ESTIMATION ARCHITECTURE WITH COMPLEMENTARY EMBEDDED MEMORY BANKS
Authors: KIM KYUNG-SAENG , LEE KWYRO
Published: May 2003

This letter describes a motion estimation architecture with complementary access types of memory banks, one for column vector access and the other for row vector access. It handles 2D image very efficiently for full-search block matching algorithm and maximizes a useful data transfer rate by reducing the overhead clocks for extra data reading and alignment. The results show that power saving is improved by using complementary access types of memory banks and amounts to 27.3% when the full-search block matching algorithm is applied for the CCIR-601 format compared to an identical design without the proposed enhancements.
AN ACCURATE EXPLORATION OF TIMING AND AREA TRADE-OFFS IN ARITHMETIC OPTIMIZATION USING CARRY-SAVE-ADDERS
Authors: KIM YOUNG-TAE , KIM TAEWHAN
Published: May 2003

Carry-save adder (CSA) is one of the most widely used implementation units for arithmetic circuits. However, the existing approaches to the CSA transformation have an inherent limitation in the scope of CSA application, i.e., transforming each of operation trees separately without any interaction among them, which results in a locally optimized CSA circuit. To overcome the limitation, we introduce a new concept called tree-boundary optimization techniques, based on which we propose a practically efficient algorithm for exploring timing and area trade-offs in optimizing arithmetic circuits using CSAs. The proposed algorithm is applicable to any arithmetic circuits with multiple operation trees, which appear in most filter designs. From experimentations on a number of digital filter designs, we confirm that the proposed algorithm reduces the circuit timing by 4%–40% without any area increase compared to those produced by the conventional CSA transformations.
APPLICATION OF THE TWO-DIMENSIONAL FREQUENCY DOMAIN LEAST SQUARES ALGORITHM TO AIRBORNE SURVEILLANCE RADAR DETECTION
Authors: ZHANG QINGWEN , MIKHAEL WASFY B.
Published: May 2003

The application of the two-dimensional frequency domain least squares (2D–FD–LS) algorithm to parametric-based airborne radar detection is discussed herein. Several issues such as model order selection and model stabilization are considered. The frequency-domain version of the test statistic is also derived here. Simulation-based results demonstrate that good performance can be obtained.
A NOVEL ANALYTICAL SPACE-VARIANT POINT SPREAD FUNCTION MODEL FOR UNDERCORRECTED OPTICAL SYSTEMS
Authors: COSTELLO THOMAS P. , MIKHAEL WASFY B.
Published: May 2003

An analytical model is developed for the space-variant (SV) point-spread-function (PSF) of an undercorrected optical system with a rectangular aperture. The model accommodates broadening and shifting of the central lobe, as well as sidelobe asymmetry of the PSF, as field angle increases. These effects are exhibited by diffraction-based PSF models. The proposed model uses eight parameters for any specific field position, compared to ~ 210 parameters required for direct sampling of an individual PSF. The model is adapted to PSFs developed from diffraction theory using an adaptive system with gradient descent parameter adjustment. Consequently, the model is useful for applying certain SV digital image restoration methods because it significantly reduces the memory required to store PSF sample functions. In addition, the model does not require samples of the PSF or a DFT operation to obtain samples of the optical transfer function (OTF). Thus, the efficiency of SV restoration methods applied in the frequency domain, such as sectioning approaches, is further improved. Data presented confirms the accuracy and the computational advantage of the model by quantifying its adaptation to a physical PSF over a range of field angles.
AN APPROACH TO OBJECT SYSTEM MODELING BY STATE-BASED OBJECT PETRI NETS
Authors: NEWMAN A. , SHATZ S. M. , XIE X.
Published: May 2003

For many years, Petri nets have been used for modeling the behavior of various types of concurrent systems. While these net models are especially well suited to capture the behavior of concurrent systems, it is still the case that net models do not easily capture some important structural aspects of a system, such as modularity. In terms of software systems for distributed applications, the object-oriented paradigm has become a standard for defining modularity and reuse of software. Thus, an evolving direction in Petri net technology is the blending of net features with object-oriented capability. This paper discusses one such approach for state-based object systems.
A SYMBOLIC CIRCUIT MODELING PROGRAM FOR DC/DC POWER CONVERTER CIRCUITS
Authors: LAI Y. M. , TSE C. K. , MEHTA P.
Published: May 2003

In this letter a computer-based symbolic circuit modeling program, applicable to any arbitrary PWM dc/dc converter circuit, is presented. From the circuit description, this program automatically generates a time-invariant averaged model which represents the low frequency behavior of the original circuit. With the aid of a general simulation program such as SPICE, the low frequency characteristics of the circuit can be easily obtained.
GENERALISED SPLIT-RADIX ALGORITHMS FOR DFT
Authors: BI GUOAN , KOT A. C. , MENG ZIHOU
Published: May 2003

This letter presents a general split-radix algorithm based on the decimation-in-time decomposition. It can flexibly compute the discrete Fourier transforms of length-q*2m where q is an odd integer. In comparison with other reported algorithms, our proposed one supports a wider range of sequence lengths, achieves a reduction of arithmetic operations and requires a simple computational structure.
ROUTING SPACE ESTIMATION AND ASSIGNMENT FOR MACRO-CELL PLACEMENT
Authors: YAN JIN-TAI
Published: May 2003

In general, the routing space between two adjacent macro-cells is estimated and assigned after completing the placement of all the macro-cells. In this paper, the routing space in a macro-cell placement is divided into straight channels. First, based on a probabilistic analysis, a new routing space estimation approach for a channel is proposed. For the assignment of routing space between two adjacent macro-cells, it is desired that this assignment does not change the topological relation between any pair of adjacent macro-cells in a macro-cell placement. Hence, the assignment of a previous channel will not be modified by the assignment of a recent channel during the assignment process of routing space. A safe routing space assignment approach is further proposed for obtaining a complete macro-cell placement. It is proved that the time complexity of a safe routing space assignment is O(Nlog N), where N is the number of macro-cells in a macro-cell netlist. Finally, the experimental results show that the proposed estimation and assignment of routing space is effective in a macro-cell placement.
A LEARNING PARALLEL ANALOG-TO-DIGITAL VECTOR QUANTIZER
Authors: LUBKIN JEREMY , CAUWENBERGHS GERT
Published: May 2003

A mixed-mode VLSI architecture for learning vector quantization (LVQ), with on-chip adaptation and dynamic storage of the analog templates, converts analog vectorial data in parallel to digital format. The architecture is digitally configurable, and extends to commonly used algorithms for codebook adaptation besides k-means clustering such as Fuzzy Adaptive Resonance Theory (ART) and Kohonen self-organizing maps. The analog memory and adaptive element of the LVQ cell comprise 6 MOS transistors and one capacitor, and provide for robust self-refresh of the dynamic analog storage. Total cell size including distance and adaptive computations is 80×70 lambda in scalable MOSIS technology. Experimental results from a fabricated 16×16 cell prototype in 2μm CMOS are included.
ON THE MASS NEUTRINO PHASE ALONG THE GEODESIC LINE AND THE NULL LINE IN CURVED AND FLAT SPACETIME
Authors: ZHANG C. M. , BEESHAM A.
Published: May 2003

On the mass neutrino phase calculations along both the particle geodesic line and the photon null line, there exists a double counting, a factor of 2, when comparing the geodesic phase with the null phase. Moreover, we compare the phase calculations with the same-energy description and the same-momentum description by means of the Minkowski diagram, and obtain the practical equivalence of these two descriptions. On the same-velocity description, although not corresponding any real physical process, we still indicate its phase calculation in the Minkowski diagram, which has the same result as those of same-energy and same-momentum cases. Furthermore, in the curved spacetime, we also prove the existence of the double counting of the geodesic phase to the null phase. Our conclusions are the same as others' results by the different methods.
RUDIMENTS OF HOLOGRAPHY
Authors: ÁLVAREZ ENRIQUE , CONDE JORGE , HERNÁNDEZ LORENZO
Published: May 2003

An elementary introduction to Maldacena's AdS/CFT correspondence is given, with some emphasis in the Fefferman–Graham construction. This is based on lectures given by one of us (E.A.) at the Universidad Autonoma de Madrid.
SYMPLECTIC CUTS AND PROJECTION QUANTIZATION FOR NON-HOLONOMIC CONSTRAINTS
Authors: BOJOWALD MARTIN , STROBL THOMAS
Published: May 2003

Projection quantization, which is a method to quantize systems with non-holonomic constraints like the condition Det q > 0 in general relativity, is shown to coincide with a reduced phase space quantization in a class of cases which is specified in the main text. This is inferred in the context of geometric quantization using the symplectic cutting technique.
RADIATING SPHERICAL COLLAPSE WITH HEAT FLOW
Authors: GOVENDER M. , GOVINDER K. S. , MAHARAJ S. D. , SHARMA R. , MUKHERJEE S. , DEY T. K.
Published: May 2003

We present here a simple model of radiative gravitational collapse with radial heat flux which describes qualitatively the stages close to the formation of a superdense cold star. Starting with a static general solution for a cold star, the model can generate solutions for the earlier evolutionary stages. The temporal evolution of the model is specified by solving the junction conditions appropriate for radiating gravitational collapse. The results will be useful in constructing models for the evolution of X-ray pulsars, like Her X-1.
FLUCTUATION SPECTRUM FROM A SCALAR-TENSOR BIMETRIC GRAVITY THEORY
Authors: CLAYTON M. A. , MOFFAT J. W.
Published: May 2003

Predictions of the CMB spectrum from a bimetric gravity theory (BGT)1 are presented. The initial inflationary period in BGT is driven by a vanishingly small speed of gravitational waves vg in the very early universe. This initial inflationary period is insensitive to the choice of scalar field potential and initial values of the scalar field. After this initial period of inflation, vg will increase rapidly and the effects of a potential will become important. We show that a quadratic potential introduced into BGT yields an approximately flat spectrum with inflation parameters: ns=0.98, nt=-0.027, αs=-3.2×10-4 and αt=-5.0×10-4, with r ≥ 0.014.
A NOTE ON THE COSMOLOGICAL DYNAMICS IN FINITE-RANGE GRAVITY
Authors: SAMI M.
Published: May 2003

In this note we consider the homogeneous and isotropic cosmology in the finite-range gravity theory recently proposed by Babak and Grishchuk. In this scenario the universe undergoes late time accelerated expansion if both the massive gravitons present in the model are tachyons. We carry out the phase space analysis of the system and show that the late-time acceleration is an attractor of the model.
CONICAL SINGULAR SOLUTIONS IN (2+1)-DIMENSIONAL GRAVITY EMPLOYING THE ADM CANONICAL FORMALISM
Authors: KENMOKU MASAKATSU , UCHIDA SATOKO , MATSUYAMA TOYOKI
Published: May 2003

Topological solutions in the (2+1)-dimensional Einstein theory of gravity are studied within the ADM canonical formalism. It is found that a conical singularity appears in the closed expanding de Sitter universe solution as a topological defect in the case of the Einstein theory with a cosmological constant. Quantum effects on the conical singularity are studied using the de Broglie-Bohm interpretation. Finite quantum tunneling effects are obtained for the closed de Sitter universe, while no quantum effects are obtained for an open universe.
ON THE PRIMORDIAL MAGNETIC FIELD FROM DOMAIN WALLS
Authors: CEA P. , TEDESCO L.
Published: May 2003

In this paper we discuss once more the zero mode contribution to the vacuum energy density. We show that a careful treatment of the zero modes leads to the conclusion that domain walls may be ferromagnetic, and could generate a magnetic field of cosmological interest.
ESSENTIAL AND INESSENTIAL FEATURES OF HAWKING RADIATION
Authors: VISSER MATT
Published: May 2003

There are numerous derivations of the Hawking effect available in the literature. They emphasise different features of the process, and sometimes make markedly different physical assumptions. This article presents a "minimalist" argument, and strips the derivation of as much excess baggage as possible. All that is really necessary is quantum physics plus a slowly evolving future apparent horizon (not an event horizon). In particular, neither the Einstein equations nor Bekenstein entropy are necessary (nor even useful) in deriving Hawking radiation.
SCALE INVARIANT COSMOLOGY II: EXTRA DIMENSIONS AND THE REDSHIFT OF DISTANT SUPERNOVAE
Authors: PETIT JEAN-PIERRE , MIDY PIERRE
Published: May 2003

The cosmological problem is studied here starting from a metric with a variable scale factor for time and two different ones for space, noted R for ordinary space and S for the extra dimensions. Once R has been obtained from physical principles, one is left for S with a differential equation which can be solved through Lie group analysis and dynamical systems theory, and a frequent use of computer algebra has been made in the ensuing calculations. This leads to a good agreement with the recent observational results relating to distant supernovae. However, the solution obtained for S is particularly simple if spacetime has a dimension at least equal to ten, a result to be compared with those given by superstring or M theories.
NON-MARGINALLY BOUND INHOMOGENEOUS DUST COLLAPSE IN HIGHER DIMENSIONAL SPACE–TIME
Authors: GHOSH S. G. , BANERJEE A.
Published: May 2003

We investigate the occurrence and nature of a naked singularity in the gravitational collapse of an inhomogeneous dust cloud described by a self-similar higher dimensional Tolman–Bondi space–time. Bound, marginally bound and unbound space–times are analyzed. The degree of inhomogeneity of the collapsing matter necessary to form a naked singularity is given.
STUDY OF PROTO STRANGE STARS IN TEMPERATURE AND DENSITY DEPENDENT QUARK MASS MODEL
Authors: GUPTA V. K. , GUPTA ASHA , SINGH S. , ANAND J. D.
Published: May 2003

We report on the study of the mass–radius (M–R) relation and the radial oscillations of proto strange stars. For the quark matter we have employed the very recent modification, the temperature and density dependent quark mass model of the well known density dependent quark mass model. We find that the maximum mass the star can support increases significantly with the temperature of the star in this model which implies that transition to a black hole at the early stage of formation of the star is inhibited. As for the effect of the neutrinos, we find, contrary to expectation, that the values of mass, radius and oscillation frequencies are almost independent of the neutrino chemical potentials.
X-RAY SPECTRAL ANALYSIS OF SU UMa TYPE DWARF NOVAE OBSERVED WITH ROSAT
Authors: GÜN GÜLNUR ÝKİS , ERCAN E. NİHAL
Published: May 2003

X-ray spectral parameters were determined for eight SU UMa type Dwarf Novae observed with the ROSAT PSPC. The raw data were fitted with various spectral models and the best fit spectral models are found to be that of Raymond–Smith and Thermal Bremsstrahlung. The best fit temperatures were estimated to be between kT ~ 1.1-1.8 keV while the Column Densities were found to be between NH ~ 2.4×1020-4.1×1020 cm -2. The estimated 0.1-2.4 keV fluxes were in the range of log FX=-13 to -11 ergs cm-2 s-1. FX/F UV and FX/F opt rates were calculated to be between ~0.09 and ~0.37. This shows that most of the energy is radiated in the Optical and Ultraviolet band from the accretion disk in the quiescent state.

Many of the SU UMa type Dwarf Novae show an Ultraviolet lag in their outburst spectrum, the Coronal Siphon Flow Model of Meyer and Meyer-Hofmeister may explain this phenomenon. This model proposes a corona at the boundary layer of a system when it is a quiescent state and suggests that some parts of the X-rays come from the corona. For these reasons, the equations of this model were applied to the results of the spectral analysis. Using this model, the mass accretion rates, the mass evaporation rates, and the radii of the coronas were calculated to be ~10-12.3-10-11.3 M⊙ yr -1, ~10-6.5-10-5.5 g cm -2 s -1 and ~109.1-109.9 cm , respectively. The pressures in the coronas were less than ~1200 g cm -2 s -1 for (z) up to ~10×109 cm . The obtained values suggest that the Corona model can indeed operate in SU UMa type Dwarf Novae.
ESTIMATES FOR THE ERROR TERM IN A UNIFORM ASYMPTOTIC EXPANSION OF THE JACOBI POLYNOMIALS
Authors: WONG R. , ZHAO Y.-Q.
Published: May 2003

There are now several ways to derive an asymptotic expansion for [Formula: see text], as n → ∞, which holds uniformly for [Formula: see text]. One of these starts with a contour integral, involves a transformation which takes this integral into a canonical form, and makes repeated use of an integration-by-parts technique. There are two advantages to this approach: (i) it provides a recursive formula for calculating the coefficients in the expansion, and (ii) it leads to an explicit expression for the error term. In this paper, we point out that the estimate for the error term given previously is not sufficient for the expansion to be regarded as genuinely uniform for θ near the origin, when one takes into account the behavior of the coefficients near θ = 0. Our purpose here is to use an alternative method to estimate the remainder. First, we show that the coefficients in the expansion are bounded for [Formula: see text]. Next, we give an estimate for the error term which is of the same order as the first neglected term.
UNIFORM ASYMPTOTIC APPROXIMATIONS FOR THE WHITTAKER FUNCTIONS Mκ,iμ(z) AND Wκ,iμ(z)
Authors: DUNSTER T. M.
Published: May 2003

Uniform asymptotic approximations are obtained for the Whittaker's confluent hypergeometric functions Mκ, iμ(z) and Wκ, iμ(z), where κ, μ and z are real. Three cases are considered, and when taken together, result in approximations which are valid for κ → ∞ uniformly for 0 ≤ μ < ∞, 0 < z < ∞, and also for μ → ∞ uniformly for 0 ≤ κ < ∞, 0 < z < ∞. The results are obtained by an application of general asymptotic theories for differential equations either having a coalescing turning point and double pole with complex exponent, or a fixed simple turning point. The resulting approximations achieve a uniform reduction of free variables from three to two, and involve either modified Bessel functions or Airy functions. Explicit error bounds are available for all the approximations.
DISCRETE ANALOGUES OF THE LAGUERRE INEQUALITY
Authors: KRASIKOV ILIA
Published: May 2003

It is shown that [Formula: see text], m = 0,1,…, where f(x) is either a real polynomial with only real zeros or an allied entire function of a special type, provided that the distance between two consecutive zeros of f(x) is at least [Formula: see text]. These inequalities are surprisingly similar discrete analogues of higher degree generalizations of the Laguerre and Turán inequalities. Applied to the classical discrete orthogonal polynomials, they yield sharp, explicit bounds, uniform in all parameters involved, on the polynomials and their extreme zeros. This is illustrated for the case of Krawtchouk polynomials.
A LAGUERRE POLYNOMIAL ORTHOGONALITY AND THE HYDROGEN ATOM
Authors: DUNKL CHARLES F.
Published: May 2003

The radial part of the wave function of an electron in a Coulomb potential is the product of a Laguerre polynomial and an exponential with the variable scaled by a factor depending on the degree. This note presents an elementary proof of the orthogonality of wave functions with differing energy levels. It is also shown that this is the only other natural orthogonality for Laguerre polynomials. By expanding in terms of the usual Laguerre polynomial basis, an analogous strange orthogonality is obtained for Meixner polynomials.
SOLUTION ESTIMATES OF NONLINEAR VECTOR VOLTERRA–STIELTJES EQUATIONS
Authors: GIL' M. I. , KLOEDEN P. E.
Published: May 2003

Supremum and L2-norms estimates of the solutions of nonlinear vector Volterra–Stieltjes equations in the complex Euclidean space [Formula: see text] are derived using recently established estimates for the norm of vector-valued functions and the resolvents of quasi–nilpotent operators. Such equations include both continuous time Volterra integral equations and discrete time Volterra difference equations as well as mixtures of these two basic types of time scales. The estimates are formulated in terms of the coefficients of the equations, which are separated into a linear part and a nonlinear part satisfying a local Lipschitz condition. Stability conditions are then derived from these estimates.
WEYL TRANSFORMS ASSOCIATED WITH THE SPHERICAL MEAN OPERATOR
Authors: RACHDI L. T. , TRIMÈCHE K.
Published: May 2003

Using the harmonic analysis associated with the spherical mean operator ℛ, we define and study the Weyl transforms Wσ associated with ℛ where σ is a symbol in Sm, m ∈ ℝ, and we give criteria in terms of σ to obtain the boundedness and compactness of the transform Wσ.
LIFE-OF-PROJECT ENVIRONMENTAL MANAGEMENT STRATEGY: CASE STUDY OF THE CONFEDERATION BRIDGE PROJECT, CANADA
Authors: BARNES JEFFREY L. , LEMON DAVID
Published: May 2003

The developer of the Confederation Bridge Project in eastern Canada is successfully implementing a life-of-project environmental management strategy for this privately-funded public project. The cornerstone of this strategy is the Environmental Management Plan (EMP), an umbrella document which describes how the developer is managing all environmental aspects of the project throughout the construction phase and the subsequent 35-year period of private ownership. The EMP is comprised of several dynamic plans and programmes. Owing to unique circumstances, the EMP was developed prior to the completion of the environmental assessment, providing an example of the benefit of such, especially for a finance-build-own-operate-transfer infrastructure project. The experience of this project leads to the conclusion that the use of environmental management systems to encapsulate environmental management strategies early in project planning would be beneficial.
On a nonlinear compactness lemma in Lp(0, T; B)
Authors: Maitre Emmanuel
Published: May 2003

We consider a nonlinear counterpart of a compactness lemma of
Simon (1987), which arises naturally in the study of doubly
nonlinear equations of elliptic‐parabolic type. This
paper was motivated by previous results of Simon (1987), recently
sharpened by Amann (2000), in the linear setting, and by a
nonlinear compactness argument of Alt and Luckhaus (1983).
Angiotensin II Inhibits Endothelial Cell Motility Through an AT1-Dependent Oxidant-Sensitive Decrement of Nitric Oxide Availability
Authors: Desideri Giovambattista , Bravi Maria Cristina , Tucci Marzia , Croce Giuseppe , Marinucci Maria Contina , Santucci Anna , Alesse Edoardo , Ferri Claudio
Published: May 2003

Objective—The migratory capability of vascular endothelial cells plays a pivotal role in the maintenance of vessel wall integrity and is stimulated by nitric oxide (NO). Angiotensin II increases NAD(P)H oxidase activity in endothelial cells, thereby promoting reactive oxygen species (ROS) generation. Because ROS can both reduce NO synthase activity and increase NO breakdown, thus impairing NO availability in endothelial cells, we evaluated the effect of angiotensin II on human vascular endothelial cell (HUVEC) motility.

Methods and Results—Angiotensin II dose- and time-dependently reduced HUVEC migration. Besides inhibiting HUVEC motility, angiotensin II altered intracellular glutathione redox status. The generation of ROS by cultured HUVECs was significantly increased by angiotensin II. Furthermore, angiotensin II reduced NO metabolite concentrations in culture media. The angiotensin II type 1 receptor antagonist candesartan cilexetil attenuated the inhibitory action exerted by angiotensin II on HUVEC motility, reversed the angiotensin II-induced increase in intracellular oxidative stress, and restored NO availability. Similar effects were exerted by the flavonoid inhibitor diphenylene iodinium and the antioxidant agentN-acetyl-l-cysteine.

Conclusions—All together, our data demonstrate that angiotensin II inhibits HUVEC motility by reducing NO availability. Such reduction is due to an angiotensin II type 1 receptor-dependent increment in intracellular ROS generation.
Electron Spin Resonance Detection of Hydrogen Peroxide as an Endothelium-Derived Hyperpolarizing Factor in Porcine Coronary Microvessels
Authors: Matoba Tetsuya , Shimokawa Hiroaki , Morikawa Keiko , Kubota Hiroshi , Kunihiro Ikuko , Urakami-Harasawa Lemmy , Mukai Yasushi , Hirakawa Yoji , Akaike Takaaki , Takeshita Akira
Published: May 2003

Objective—

Endothelium-derived hyperpolarizing factor (EDHF) plays an important role in modulating vascular tone, especially in microvessels, although its nature has yet to be elucidated. This study was designed to examine whether hydrogen peroxide (H
2
O
2
) is an EDHF in porcine coronary microvessels with use of an electron spin resonance (ESR) method to directly detect H
2
O
2
production from the endothelium.

Methods and Results—

Isometric tension and membrane-potential recordings demonstrated that bradykinin and substance P caused EDHF-mediated relaxations and hyperpolarizations of porcine coronary microvessels in the presence of indomethacin and
N
ω
-nitro-
l
-arginine. The contribution of H
2
O
2
to the EDHF-mediated responses was demonstrated by the inhibitory effect of catalase and by the relaxing and hyperpolarizing effects of exogenous H
2
O
2
. Endothelial production of H
2
O
2
was quantified in bradykinin- or substance P–stimulated intact blood vessels by ESR spectroscopy. Tiron, a superoxide scavenger that facilitates H
2
O
2
formation, enhanced bradykinin-induced production of H
2
O
2
, as well as the EDHF-mediated relaxations and hyperpolarizations. By contrast, cytochrome P-450 inhibitors (sulfaphenazole or 17-octadecynoic acid) or a gap junction inhibitor (18α-glycyrrhetinic acid) failed to inhibit the EDHF-mediated relaxations. Involvement of endothelium-derived K
+
was not evident in experiments with ouabain plus Ba
2+
or exogenous K
+
.

Conclusion—

These results provide ESR evidence that H
2
O
2
is an EDHF in porcine coronary microvessels.
Nitric Oxide Regulation of Myocardial Contractility and Calcium Cycling
Authors: Khan Shakil A. , Skaf Michel W. , Harrison Robert W. , Lee Kwangho , Minhas Khalid M. , Kumar Anil , Fradley Mike , Shoukas Artin A. , Berkowitz Dan E. , Hare Joshua M.
Published: May 2003

The mechanisms by which nitric oxide (NO) influences myocardial Ca
2+
cycling remain controversial. Because NO synthases (NOS) have specific spatial localization in cardiac myocytes, we hypothesized that neuronal NOS (NOS1) found in cardiac sarcoplasmic reticulum (SR) preferentially regulates SR Ca
2+
release and reuptake resulting in potentiation of the cardiac force-frequency response (FFR). Transesophageal pacing (660 to 840 bpm) in intact C57Bl/6 mice (WT) stimulated both contractility (dP/dt
max
normalized to end-diastolic volume; dP/dt-EDV) by 51±5% (
P
<0.001) and lusitropy (tau; τ) by 20.3±2.0% (
P
<0.05). These responses were markedly attenuated in mice lacking NOS1 (NOS1
−/−
) (15±2% increase in dP/dt-EDV;
P
<0.001 versus WT; and no change in τ;
P
<0.01 versus WT). Isolated myocytes from NOS1
−/−
(≈2 months of age) also exhibited suppressed frequency-dependent sarcomere shortening and Ca
2+
transients ([Ca
2+
]
i
) compared with WT. SR Ca
2+
stores, a primary determinant of the FFR, increased at higher frequencies in WT (caffeine-induced [Ca
2+
]
i
at 4 Hz increased 107±23% above 1 Hz response) but not in NOS1
−/−
(13±26%;
P
<0.01 versus WT). In contrast, mice lacking NOS3 (NOS3
−/−
) had preserved FFR in vivo, as well as in isolated myocytes with parallel increases in sarcomere shortening, [Ca
2+
]
i
, and SR Ca
2+
stores. NOS1
−/−
had increased SR Ca
2+
ATPase and decreased phospholamban protein abundance, suggesting compensatory increases in SR reuptake mechanisms. Together these data demonstrate that NOS1 selectively regulates the cardiac FFR via influences over SR Ca
2+
cycling. Thus, there is NOS isoform-specific regulation of different facets of rate-dependent excitation-contraction coupling; inactivation of NOS1 has the potential to contribute to the pathophysiology of states characterized by diminished frequency-dependent inotropic responses.
Interleukin-1 Receptor Antagonist (IL-1RN) Genotype Modulates the Replicative Capacity of Human Endothelial Cells
Authors: Dewberry Rachael M. , Crossman David C. , Francis Sheila E.
Published: May 2003

Endothelial cells (ECs) undergo a finite number of cell divisions before growth arrest or replicative senescence, modulated in part by the proinflammatory cytokine, interleukin-1 (IL-1). IL-1 and its family members are expressed in human atherosclerotic vessels, mainly in the endothelium. EC replicative senescence and IL-1 have been associated with atherosclerosis. Genetic variants at the IL-1 locus have been associated with a variety of coronary phenotypes. In this study, we examined the relationship between the interleukin-1 receptor antagonist variable number tandem repeat allele 2 (IL-1RN*2*2) and EC replicative capacity. A significant decrease in EC cumulative population doublings (CPDs) was associated with the rare allele (IL-1RN*2*2) at IL-1RN, 8.56±0.97 (n=7) versus 13.14±1.00 (IL-1RN*1*1, n=20),
P
=0.0118. Proliferation of IL-1RN*2*2 ECs detected by Ki67 expression was also significantly reduced particularly at later passage, passage 6: 21.76±0.93% (n=6) versus 48.10±8.81% (IL-1RN*1*1, n=7) (
P
=0.0323) and passage 8: 22.48±3.08% (n=6) versus 42.29±3.06% (IL-1RN*1*1, n=7) (
P
=0.0028). IL-1RN*2 carriage was associated with increased numbers of senescent ECs. Basal apoptosis, telomerase activity, and telomere length were not different with respect to IL-1RN genotype. Addition of exogenous IL-1ra (1 ng/mL) increased CPDs in a number of human umbilical vein endothelial cell cultures and increased proliferating cells from 12.11±1.21% to 27.82±2.82% (
P
=0.0216, IL-1RN*2*2, passage 8, n=2). These data suggest genetic control of EC proliferation and life span by the IL-1 locus and imply that IL-1ra may have a function connected with EC growth.