April 2006 arXiv papers — page 32

David Duchemin

We prove that every quaternionic-contact structure can be embedded in a quaternionic manifold and define a second fundamental form for a such embedding.

S Satheesh, E Sandhya

We discuss semi-selfdecomposable laws in the minimum scheme and characterize them using an autoregressive model. Semi-Pareto and semi-Weibull laws of Pillai (1991) are shown to be semi-selfdecomposable in this scheme. Methods for deriving this class of laws are then attempted from the angle of randomization. Finally, discrete analogues of these results are a

Ruslan Sharipov

The Standard Model of the theory of elementary particles is based on the $U(1)\times SU(2)\times SU(3)$ symmetry. In the presence of a gravitation field, i. e. in a non-flat space-time manifold, this symmetry is implemented through three special vector bundles. Connections associated with these vector bundles are studied in this paper. In the Standard Model

Oliver Goertsches

Motivated by a paper of Zirnbauer, we develop a theory of Riemannian supermanifolds up to a definition of Riemannian symmetric superspaces. Various fundamental concepts needed for the study of these spaces both from the Riemannian and the Lie theoretical viewpoint are introduced, e.g. geodesics, isometry groups and invariant metrics on Lie supergroups and ho

Svante Janson

An example is given which shows that, in general, conditioned Galton-Watson trees cannot be obtained by adding vertices one by one, as has been shown in a special case by Luczak and Winkler.

Peter Kuchment

The paper discusses relations between the structure of the complex Fermi surface below the spectrum of a second order periodic elliptic equation and integral representations of certain classes of its solutions. These integral representations are analogs of those previously obtained by S. Agmon, S. Helgason, and other authors for solutions of the Helmholtz eq

Elemer E Rosinger

Nonrigid mathematical structures may no longer form usual Eilenberg - Mac Lane categories, but more general ones, as illustrated by pseudo-topologies. A rather general concept of pseudo-topology was used in constructing differential algebras of generalized functions containing the Schwartz distributions, [4-6,8-11]. These algebras proved to be convenient in

Henry Wilton

This article gives solutions to the exercises in Bestvina and Feighn's paper on Sela's work on limit groups. We prove that all constructible limit groups are limit groups and give an account of the shortening argument of Rips and Sela.

V. P. Kurenok

Using the method of Krylov's estimates, we prove the existence of weak solutions of stochastic differential equations driven by purely discontinuous Levy processes satisfying an additional assumption. The diffusion coefficient is assumed to be one and the time-dependent drift is measurable and bounded.

Senthamarai Kannan

In this paper we give top most and least indices of non vanishing cohomology modules of line bundles in the Kac Moody setting in terms of Weyl group combinatorics. We also prove a surjection Theorem.

Katarzyna Grabowska, Janusz Grabowski, PawełUrbański

A general, consistent and complete framework for geometrical formulation of mechanical systems is proposed, based on certain structures on affine bundles (affgebroids) that generalize Lie algebras and Lie algebroids. This scheme covers and unifies various geometrical approaches to mechanics in the Lagrangian and Hamiltonian pictures, including time-dependent

Vladimir S. Rabinovich, Steffen Roch

We establish a necessary and sufficient criterion for the Fredholmness of a general locally compact band-dominated operator $A$ on $L^p(R)$ and solve the long-standing problem of computing its Fredholm index in terms of the limit operators of $A$. The results are applied to operators of convolution type with almost periodic symbol.

kais Hamza, Fima C. Klebaner

We construct a family of non-Gaussian martingales the marginals of which are all Gaussian. We give the predictable quadratic variation of these processes and show they do not have continuous paths. These processes are Markovian and inhomogeneous in time, and we give their infinitesimal generators. Within this family we find a class of piecewise deterministic

N. V. Krylov

The maximum principle for SPDEs is established in multidimensional $C^{1}$ domains. An application is given to proving the Hölder continuity up to the boundary of solutions of one-dimensional SPDEs.

Doyoon Kim, N. V. Krylov

We investigate the unique solvability of second order parabolic equations in non-divergence form in $W_p^{1,2}((0,T) \times \bR^d)$, $p \ge 2$. The leading coefficients are only measurable in either one spatial variable or time and one spatial variable. In addition, they are VMO (vanishing mean oscillation) with respect to the remaining variables.

Junhao Shen

We introduce "embedding dimensions" of a family of generators of a finite von Neumann algebra when the von Neumann algebra can be faithfully embedded into the ultrapower of the hyperfinite II$_1$ factor. These embedding dimensions are von Neumann algebra invariants, i.e., do not depend on the choices of the generators. We also find values of these in

John Crisp, Marcelo Laca

We study the quotients of the Toeplitz C*-algebra of a quasi-lattice ordered group (G,P), which we view as crossed products by a partial actions of G on closed invariant subsets of a totally disconnected compact Hausdorff space, the Nica spectrum of (G,P). Our original motivation and our main examples are drawn from right-angled Artin groups, but many of our

Ahmed Abbes, Takeshi Saito

We introduce the characteristic class of an l-adic etale sheaf using a cohomological pairing due to Verdier (SGA5). As a consequence of the Lefschetz-Verdier trace formula, its trace computes the Euler-Poincare characteristic of the sheaf. We compare the characteristic class to two other invariants arising from ramification theory. One is the Swan class of K

Takashi Aoki, Shuzo Izumi, Yasuo Ohno, Manabu Ozaki

Let S be a set of n ideals of a commutative ring A. Let G_{even} (respectively G_{odd}) denote the product of all the sums of even (respectively odd) number of ideals of S. If n<7 the product of G_{even} and the intersection of all ideals of S is included in G_{odd}. In the case A is an Noetherian integral domain, this inclusion is replaced by equality if an

Masanori Asakura

Modular section added

Almut Burchard, Hichem Hajaiej

The rearrangement inequalities of Hardy-Littlewood and Riesz say that certain integrals involving products of two or three functions increase under symmetric decreasing rearrangement. It is known that these inequalities extend to integrands of the form F(u_1,..., u_m) where F is supermodular; in particular, they hold when F has nonnegative mixed second deriv

Jon P. Bannon, Mohan Ravichandran

In this article we introduce an isomorphism invariant for type II_1 factors using the Connes-Folner condition. We compute bounds of this number for free group factors.

Amnon Yekutieli, James J. Zhang

A quasi-coherent ringed scheme is a pair (X,A), where X is a scheme, and A is a noncommutative quasi-coherent O_X-ring. We introduce dualizing complexes over quasi-coherent ringed schemes and study their properties. For a separated differential quasi-coherent ringed scheme of finite type over a field, we prove existence and uniqueness of a rigid dualizing co

Josef L. P. Karthauser, P. M. Saffin

In this paper we consider cosmological scaling solutions in general relativity coupled to scalar fields with a non-trivial moduli space metric. We discover that the scaling property of the cosmology is synonymous with the scalar fields tracing out a particular class of geodesics in moduli space - those which are constructed as integral curves of the gradient

Rutger Boels, Lionel Mason, David Skinner

We construct a twistor space action for N=4 super Yang-Mills theory and show that it is equivalent to its four dimensional spacetime counterpart at the level of perturbation theory. We compare our partition function to the original twistor-string proposal, showing that although our theory is closely related to string theory, it is free from conformal supergr

Makoto Sakaguchi, Kentaroh Yoshida

We explore noncommutative D-branes in the AdS_5xS^5 background from the viewpoint of κ-invariance of a covariant open string action in the Green-Schwarz formulation. Boundary conditions to ensure the κ-invariance of the action lead to possible configurations of noncommutative D-branes. With this covariant method, we derive configurations of 1/4 BPS noncommut

S. J. Gates, S. Penati, G. Tartaglino-Mazzucchelli

In this note, we establish the formulation of 6D, N=1 hypermultiplets in terms of 4D chiral-nonminimal (CNM) scalar multiplets. The coupling of these to 6D, N=1 Yang-Mills multiplets is described. A 6D, N=1 projective superspace formulation is given in which the above multiplets naturally emerge. The covariant superspace quantization of these multiplets is s

Victor Gayral, Bruno Iochum, Joseph C. Varilly

We extend the isospectral deformations of Connes, Landi and Dubois-Violette to the case of Riemannian spin manifolds carrying a proper action of the noncompact abelian group $R^l$. Under deformation by a torus action, a standard formula relates Dixmier traces of measurable operators to integrals of functions on the manifold. We show that this relation persis

Marcelo Gleiser, Rafael C. Howell

We investigate the emergence of time-dependent nonperturbative configurations during the evolution of nonlinear scalar field models with symmetric and asymmetric double-well potentials. Complex spatio-temporal behavior emerges as the system seeks to establish equipartition after a fast quench. We show that fast quenches may dramatically modify the decay rate

Stefan Leupold

As an alternative to the two-quark condensate we propose a specific four-quark condensate as an order parameter of chiral symmetry restoration. We show that this four-quark condensate is closer connected to observable quantities. Within a resonance gas model we calculate the in-medium changes of two- and four-quark condensate as functions of temperature and

Ph. Boucaud, Th. Brüntjen, J. P. Leroy, A. Le Yaouanc

We show that a finite non-vanishing ghost dressing function at zero momentum satisfies the scaling properties of the ghost propagator Schwinger-Dyson equation. This kind of Schwinger-Dyson solutions may well agree with lattice data and provides an interesting alternative to the widely spread claim that the gluon dressing function behaves like the inverse squ

Stefan Leupold

A current-current correlator with the quantum numbers of the omega meson is studied in a nuclear medium. Using weighted finite energy sum rules and dispersion relations for the current-nucleon forward scattering amplitude it is shown that strict vector meson dominance and QCD sum rules are incompatible with each other. This implies that at least one of these

Birger Steinmueller, Stefan Leupold

The possible in-medium changes of the properties of an omega meson placed in cold nuclear matter are constrained by QCD sum rules. It is shown that the sum rules cannot fully determine the in-medium spectral shape of the omega meson. However, for a given parameterization the sum rules can constrain or correlate the hadronic parameters. It is shown that weigh

A. Mitov, S. Moch, A. Vogt

We have investigated the next-to-next-to-leading order (NNLO) corrections to inclusive hadron production in e^+e^- annihilation and the related parton fragmentation distributions, the `time-like&#39; counterparts of the `space-like&#39; deep-inelastic structure functions and parton densities. We have re-derived the corresponding second-order coefficient func

Boris A. Arbuzov, Mikhail K. Volkov, Ivan V. Zaitsev

We apply Bogolubov approach to QCD with two light quarks to demonstrate a spontaneous generation of an effective interaction, leading to the Nambu -- Jona-Lasinio model. The resulting theory contains two parameters: average low-energy value of $α_s$ and current light quark mass $m_0$. All other low-energy parameters: the pion decay constant, mass of the $π$-

Bryan Webber

In theories with large extra dimensions and TeV-scale gravity, black holes are copiously produced in particle collisions at energies well above the Planck scale. I briefly review some recent work on the phenomenology of this process, with emphasis on theoretical uncertainties and possible strategies for measuring the number of extra dimensions.

D0 Collaboration, V. Abazov

We present a search for the flavor-changing neutral current decay B0_s -> phi mu+ mu- using about 0.45 fb^-1 of data collected in p \bar p collisions at sqrt{s} =1.96 TeV with the DØdetector at the Fermilab Tevatron Collider. We find an upper limit on the branching ratio of this decay normalized to B0_s -> J/psi phi of B(B0_s -> phi mu+ mu-)/B(B0_s -> J/psi

The BABAR Collaboration, B. Aubert

A search for the decay of the tau lepton to five charged and two neutral pions is performed using data collected by the BABAR detector at the PEP-II asymmetric-energy e+e- collider. The analysis uses 232 fb-1 of data at center-of-mass energies on or near the Y(4S) resonance. We observe 10 events with an expected background of 6.5^{+2.0}_{-1.4} events. In the

The BABAR Collaboration, B. Aubert

We report the observation of decays B0->D_s(*)+pi- and B0->D_s(*)-K+ in a sample of 230*10^6 Upsilon(4S)->BBbar events recorded with the BaBar detector at the PEP-II asymmetric-energy e+e- storage ring. We measure the branching fractions B(B0->D_s+pi-)=(1.3 +/- 0.3 (stat.) +/- 0.2 (syst.))*10^{-5}, B(B0->D_s-K+)=(2.5 +/- 0.4 (stat.) +/- 0.4 (syst.))*10^{-5},

R. A. d&#39;Inverno, P Lambert, J. A. Vickers

We derive a canonical analysis of a double null 2+2 Hamiltonian description of General Relativity in terms of complex self-dual 2-forms and the associated SO(3) connection variables. The algebra of first class constraints is obtained and forms a Lie algebra that consists of two constraints that generate diffeomorphisms in the two surface, a constraint that g

Parthasarathi Majumdar

Beginning with a brief sketch of the derivation of Hawking&#39;s theorem of horizon area increase, based on the Raychaudhuri equation, we go on to discuss the issue as to whether generic black holes, undergoing Hawking radiation, can ever remain in stable thermal equilibrium with that radiation. We derive a universal criterion for such a stability, which rel

V. Dorofeev

Gravitational interactions are treated as non-associative part of a Lagrangian of octonion fields. The Lagrangian is defined in the charge space as squared curvature with respect to the octonion fields. The applications of suggested formalism to homogeneous and isotropic space are studied.

Joel Friedman

In a previous paper we have suggested a number of ideas to attack circuit size complexity with cohomology. As a simple example, we take circuits that can only compute the AND of two inputs, which essentially reduces to SET COVER. We show a very special case of the cohomological approach (one particular free category, using injective and superskyscraper sheav

Sameet Sreenivasan, Reuven Cohen, Eduardo López, Zoltán Toroczkai

We consider the effects of network topology on the optimality of packet routing quantified by $γ_c$, the rate of packet insertion beyond which congestion and queue growth occurs. The key result of this paper is to show that for any network, there exists an absolute upper bound, expressed in terms of vertex separators, for the scaling of $γ_c$ with network si

Nima Sarshar, Behnam A. Rezaei, Vwani P. Roychowdhury

This paper is concerned with the scaling of the number of hops in a large scale wireless ad-hoc network (WANET), a quantity we call network latency. A large network latency affects all aspects of data communication in a WANET, including an increase in delay, packet loss, required processing power and memory. We consider network management and data routing ch

K. Venkatesh Prasad, TJ Giuli, David Watson

Over the past five years, there has been considerable growth and established value in the practice of modeling automotive software requirements. Much of this growth has been centered on requirements of software associated with the established functional areas of an automobile, such as those associated with powertrain, chassis, body, safety and infotainment.

Xenofontas Dimitropoulos, Dmitri Krioukov, George Riley, kc claffy

Although the Internet AS-level topology has been extensively studied over the past few years, little is known about the details of the AS taxonomy. An AS &#34;node&#34; can represent a wide variety of organizations, e.g., large ISP, or small private business, university, with vastly different network characteristics, external connectivity patterns, network g

Jeremy Avigad, Kevin Donnelly, David Gray, Paul Raff

The prime number theorem, established by Hadamard and de la Vall&#39;ee Poussin independently in 1896, asserts that the density of primes in the positive integers is asymptotic to 1 / ln x. Whereas their proofs made serious use of the methods of complex analysis, elementary proofs were provided by Selberg and Erd&#34;os in 1948. We describe a formally verifi

Yongxi Cheng, Xi Chen, Yiqun Lisa Yin

Suppose $P_n=\{1,2,...,n\}$ is a partially ordered set with the partial order defined by divisibility, that is, for any two distinct elements $i,j\in P_n$ satisfying $i$ divides $j$, $i<_{P_n} j$. A table $A_n=\{a_i|i=1,2,...,n\}$ of distinct real numbers is said to be \emph{consistent} with $P_n$, provided for any two distinct elements $i,j\in \{1,2,...,n\}

Rafael C. Howell, Steven D. Conradson, Angel J. Garcia-Adeva

The phase coexistence of chemically ordered L1_0 and chemically disordered structures within binary alloys is investigated, using the NiMn system as an example. Theoretical and numerical predictions of the signatures one might expect in data from local and extended probes are presented, in an attempt to explain the presence of antiferromagnetism in NiMn when

Paolo Schwendimann, Antonio Quattropani

A model describing amplification and quantum statistics of the exciton polaritons with k=0 in a non-resonantly excited semiconductor quantum well embedded in a microcavity is presented. Exploiting the bottleneck effect for exciton polaritons, it is assumed that the polaritons with k different from 0 act as a reservoir. The time evolution of the k=0 polariton

Guangming Luo, Sarka Malkova, Jaesung Yoon, David G. Schultz

Synchrotron x-ray reflectivity is used to study ion distributions at the liquid-liquid interface between a nitrobenzene solution of tetrabutylammonium tetraphenylborate (TBATPB) and a water solution of tetrabutylammonium bromide (TBABr). The concentration of TBABr is varied to alter the ion distribution. Our x-ray measurements are inconsistent with several c

S. Ospelkaus, C. Ospelkaus, O. Wille, M. Succo

We observe a localized phase of ultracold bosonic quantum gases in a 3-dimensional optical lattice induced by a small contribution of fermionic atoms acting as impurities in a Fermi-Bose quantum gas mixture. In particular we study the dependence of this transition on the fermionic 40K impurity concentration by a comparison to the corresponding superfluid to

G. Mohammadkhani, M. Zareyan

We study the effect of the interfacial transparency on the Josephson current in a diffusive ferromagnetic contact between two superconductors. In contrast to the cases of the fully transparent and the low-transparency interfaces, the current-phase relation is shown to be nonsinusoidal for a finite transparency. It is demonstrated that even for the nearly ful

Dmitry Pozdnyakov, Vadim Galenchik, Vladimir Borzdov, Fadei Komarov

An approach to calculation of the ionized impurity and surface roughness scattering rates of electrons in very thin semiconductor quantum wires taking into account the energy level broadening is worked out. It is assumed that all the electrons in the structure are in the electric quantum limit. The screening is taken into account while considering the ionize

Massimo Pica Ciamarra, Antonio Coniglio, Mario Nicodemi

We discuss the microscopic origin of dynamical instabilities and segregation patterns discovered in granular mixtures under oscillating horizontal shear, by investigating, via molecular dynamics simulations, the effective interaction between like-particles. This turns out to be attractive at short distances and strongly anisotropic, with a longer range repul

J. P. Keating, F. Mezzadri, M. Novaes

We propose a new correlator in one-dimensional quantum spin chains, the $s-$Emptiness Formation Probability ($s-$EFP). This is a natural generalization of the Emptiness Formation Probability (EFP), which is the probability that the first $n$ spins of the chain are all aligned downwards. In the $s-$EFP we let the spins in question be separated by $s$ sites. T

Deepa Kasinathan, A. B. Kyker, D. J. Singh

The magnetic nature of Cs$_{2}$AgF$_{4}$, an isoelectronic and isostructural analogue of La$_2$CuO$_4$, is analyzed using density functional calculations. The ground state is found to be ferromagnetic and nearly half metallic. We find strong hybridization of Ag-$d$ and F-$p$ states. Substantial moments reside on the F atoms, which is unusual for the halides

Michael Wilkinson, Bernhard Mehlig, Vlad Bezuglyy

We show quantitatively how the collision rate of droplets of visible moisture in turbulent air increases very abruptly as the intensity of the turbulence passes a threshold, due to the formation of fold caustics in their velocity field. The formation of caustics is an activated process, in which a measure of the intensity of the turbulence, termed the Stokes

Semen A. Trygubenko, David J. Wales

Analysing stationary point databases to extract phenomenological rate constants can become time-consuming for systems with large potential energy barriers. In the present contribution we analyse several different approaches to this problem. First, we show how the original rate constant prescription within the discrete path sampling approach can be rewritten

Gautam I. Menon

Three problems in the statistical mechanics of models for an assembly of molecular motors interacting with cytoskeletal filaments are reviewed. First, a description of the hydrodynamical behaviour of density-density correlations in fluctuating ratchet models for interacting molecular motors is outlined. Numerical evidence indicates that the scaling propertie

B. V. Karpenko, L. D. Falkovskaya, A. V. Kuznetsov

With use of homogeneous model for magnetic sub-lattice of compound La1-x CaxMnO3 allowing for Heisenberg superexchange and double exchange between nearest neighbors the temperature dependence of spontaneous magnetization on a separate site is investigated in molecular field approximation. The difference from the usual magnets with one type of magnetic ions i

B. Gaveau, L. S. Schulman

Stochastic dynamics is generated by a matrix of transition probabilities. Certain eigenvectors of this matrix provide observables, and when these are plotted in the appropriate multi-dimensional space the phases (in the sense of phase transitions) of the underlying system become manifest as extremal points. This geometrical construction, which we call an \te

A. Camjayi, R. Chitra, M. J. Rozenberg

We study the electronic state of the doped Mott-Hubbard insulator within Dynamical Mean Field Theory. The evolution of the finite temperature spectral functions as a function of doping show large redistributions of spectral weight in both antiferromagnetic and paramagnetic phases. In particular, a metallic antiferromagnetic state is obtained with a low frequ

Ana Maria Rey, Indubala I. Satija, Charles W. Clark

Hanbury-Brown-Twiss interferometry (HBTI) is used to study integer and fractionally filled Mott Insulator (MI) phases in period-2 optical superlattices. In contrast to the quasimomentum distribution, this second order interferometry pattern exhibits high contrast fringes in the it insulating phases. Our detailed study of HBTI suggests that this interference

Tai-I Weng, G. Y. Guo

Two-dimensional (2D) honeycomb photonic crystals with cylinders and connecting walls have the potential to have a large full band gap. In experiments, 2D photonic crystals do not have an infinite height, and therefore, we investigate the effects of the thickness of the walls, the height of the slabs and the type of the substrates on the photonic bands and ga

Angela Kopp, Xun Jia, Sudip Chakravarty

In the thermodynamic limit two distinct states of matter cannot be analytic continuations of each other. Classical phase transitions are characterized by non-analyticities of the free energy. For quantum phase transitions (QPTs) the ground state energy often assumes the role of the free energy. But in a number of important cases this criterion fails to predi

N. G. Parker, R. M. W. van Bijnen, A. M. Martin

We present a comprehensive theoretical study of vortex lattice formation in atomic Bose-Einstein condensates confined by a rotating elliptical trap. We consider rotating solutions of the classical hydrodynamic equations, their response to perturbations, as well as time-dependent simulations. We discriminate three distinct, experimentally testable, regimes of

M. N. Kiselev, K. Kikoin, R. I. Shekhter, V. M. Vinokur

We investigate theoretically a mechanically assisted Kondo effect and electric charge shuttling in nanoelectromechanical single-electron transistor (NEM-SET). It is shown that the mechanical motion of the central island (a small metallic particle) with the spin results in the time dependent tunneling width which leads to effective increase of the Kondo tempe

K. P. N. Murthy

Ludwig Boltzmann had a hunch that irreversibility exhibited by a macroscopic system arises from the reversible dynamics of its microscopic constituents. He derived a nonlinear integro-differential equation - now called the Boltzmann equation - for the phase space density of the molecules of a dilute fluid. He showed that the Second law of thermodynamics emer

Jon Hakkila, Timothy W. Giblin

A simple scheme delineates Long GRBs with similar time histories using the Internal Luminosity Function power-law index and the spectral lag. Several generalizations are made about time history morphologies: 1) GRBs with long spectral lags contain fewer pulses that are broader than those found in bursts with short spectral lags, 2) short-lag bursts with smal

O. Fors

(Abridged) In the first part of this thesis, a general methodology for applying image deconvolution to wide-field CCD imagery. Results show that wavelet-based deconvolution can increase limiting magnitude up to 0.6 mag and improve limiting resolution 1 pixel with respect to original image with no astrometric accuracy degradation. In the second part, a new ob

Motoyuki Saijo, Shin&#39;ichirou Yoshida

We study the nature of non-axisymmetric dynamical instabilities in differentially rotating stars with both linear eigenmode analysis and hydrodynamic simulations in Newtonian gravity. We especially investigate the following three types of instability; the one-armed spiral instability, the low T/|W| bar instability, and the high T/|W| bar instability, where T

C. E. Navia, C. R. A. Augusto

We report results on an ``one-way light path&#39;&#39; laser diffraction experiment as a function of the laser beam alignment relative to the Earth&#39;s velocity vector obtained by COBE measurements of the Doppler shift in the cosmic microwave background radiation (CMBR). An amplified Doppler shift is observed in the diffraction images, and the effect is co

N. R. Badnell

We have calculated partial final-state resolved radiative recombination (RR) rate coefficients from the initial ground and metastable levels of all elements up to and including Zn, plus Kr, Mo, and Xe, for all isoelectronic sequences up to Na-like forming Mg-like. The data are archived according to the Atomic Data and Analysis Structure (ADAS) data class adf

Uros Seljak, Anze Slosar

String models can produce successful inflationary scenarios in the context of brane collisions and in many of these models cosmic strings may also be produced. In scenarios such as KKLMMT the string contribution is naturally predicted to be well below the inflationary signal for cosmic microwave background (CMB) temperature anisotropies, in agreement with th

Levon Pogosian, Ira Wasserman, Mark Wyman

In a recent publication, we used the data from WMAP and SDSS to constrain the primordial perturbations and to predict the B-mode polarization sourced by cosmic string networks. We have been alerted by A. Slosar to the existence of errors in the code we used to calculate the Cosmic Microwave Background anisotropies from cosmic strings. Correcting the errors l

Joern Rossa, Roeland P. van der Marel, Torsten Boeker, Joris Gerssen

(Abridged) We study the nuclear star clusters in spiral galaxies of various Hubble types using spectra obtained with STIS on-board HST. We observed the nuclear clusters in 40 galaxies, selected from two previous HST/WFPC2 imaging surveys. The spectra provide a better separation of cluster light from underlying galaxy light than is possible with ground-based

A. Mucciarelli, L. Origlia, F. R. Ferraro, C. Maraston

We present deep J,H,Ks photometry and accurate Color Magnitude Diagrams down to K ~18.5, for a sample of 13 globular clusters in the Large Magellanic Cloud. This data set combined with the previous sample of 6 clusters published by our group gives the opportunity to study the properties of giant stars in clusters with different ages (ranging from ~80 Myr up

Carl-Jakob Walcher, Torsten Boeker, Stephane Charlot, Luis C. Ho

(Abridged) As part of an ongoing effort to study the stellar nuclei of very late-type, bulge-less spirals, we present results from a high-resolution spectroscopic survey of nine such nuclear star clusters, undertaken with VLT/UVES. We fit the spectra with population synthesis models and measure Lick-type indices to determine mean luminosity-weighted ages, wh

Maurizio Salaris, Achim Weiss, Jason W. Ferguson, David J. Fusilier

Self-enrichment processes occurring in the early stages of a globular cluster lifetime are generally invoked to explain the observed CNONaMgAl abundance anticorrelations within individual Galactic globulars.We have tested, with fully consistent stellar evolution calculations, if theoretical isochrones for stars born with the observed abundance anticorrelatio

Massimo Giovannini

An appropriate gauge-invariant framework for the treatment of magnetized curvature and entropy modes is developed. It is shown that large-scale magnetic fields, present after neutrino decoupling, affect curvature and entropy perturbations. The evolution of different magnetized modes is then studied across the matter-radiation transition both analytically and

Peter M. Frinchaboy

It has been previously noted that the outermost open clusters in the Milky Way seem to lie in a string-like configuration that is coincident with, and may be associated to, the Galactic anticenter stellar structure (GASS) or the ``Monoceros Ring&#39;&#39;. Among the clusters that have been suggested to be associated with GASS are Berkeley 29 (Be29) and BH176

J. D. Kurk, A. Cimatti, E. Daddi, M. Dickinson

One of the main questions of galaxy formation is how and when galaxies assembled their mass. Observations suggest that most mass assembly and star formation occured at 1 < z < 3. However, in the same redshift range, fully assembled old and massive galaxies co-exist with star-bursting systems still in their assembling stage. In order to explore galaxy evoluti

Stan Woosley, Alexander Heger

The chief distinction between ordinary supernovae and long-soft gamma-ray bursts (GRBs) is the degree of differential rotation in the inner several solar masses when a massive star dies, and GRBs are rare mainly because of the difficulty achieving the necessary high rotation rate. Models that do provide the necessary angular momentum are discussed, with emph

Rosemary F. G. Wyse, Gerard Gilmore

The star formation, mass assembly and chemical enrichment histories of galaxies, and their present distributions of dark matter, remain encoded in their stellar populations. Distinguishing the actual distribution functions of stellar age, metallicity and kinematics at several locations in a range of galaxies, sampling across Hubble types and representative e

F. Patat, O. Ugolnikov, O. Postylyako

Twilight studies have proved to be important tools to analyze the atmospheric structure with interesting consequences on the characterization of astronomical sites. Active discussions on this topic have been recently restarted in connection with the evaluation of Dome C, Antarctica as a potential astronomical site and several site-testing experiments, includ

Dario Nunez, Roberto A. Sussman, Jesus Zavala, Lukas Nellen

We explore the use of two criteria to constraint the allowed parameter space in mSUGRA models. Both criteria are based in the calculation of the present density of neutralinos as dark matter in the Universe. The first one is the usual ``abundance&#39;&#39; criterion which is used to calculate the relic density after the ``freeze-out&#39;&#39; era. To compute

Dario Nunez, Roberto A. Sussman, Jesus Zavala, Luis G. Cabral-Rosetti

We study a dark matter halo model from two points of view: the ``stellar polytrope&#39;&#39; (SP) model coming from Tsallis&#39; thermodynamics, and the one coming from the Navarro-Frenk-White (NFW) paradigm. We make an appropriate comparison between both halo models and analyzing the relations between the global physical parameters of observed galactic disk

R. Davies, J. Thomas, R. Genzel, F. Mueller Sanchez

We report R~4300 VLT SINFONI adaptive optics integral field K-band spectroscopy of the nucleus of the Seyfert 1 galaxy NGC3227 at a spatial resolution of 0.085&#34; (7pc). We present the morphologies and kinematics of emission lines and absorption features, and give the first derivation of a black hole mass in a Seyfert 1 nucleus from spatially resolved stel

M. Massi, J. Forbrich, K. M. Menten, G. Torricelli-Ciamponi

The pre-main sequence binary system V773 Tau A shows remarkable flaring activity around periastron passage. Here, we present the observation of such a flare at a wavelength of 3 mm (90 GHz) performed with the Plateau de Bure Interferometer. We examine different possible causes for the energy losses responsible for the e-folding time of 2.3 hours of that flar

R. A. Angiras, C. J. Jog, A. Omar, K. S. Dwarakanath

The HI surface density maps for a sample of 18 galaxies in the Eridanus group are Fourier analysed. This analysis gives the radial variation of the lopsidedness in the HI spatial distribution. The lopsidedness is quantified by the Fourier amplitude $A_1$ of the $m=1$ component normalized to the average value. It is also shown that in the radial region where

J. Holder, R. W. Atkins, H. M. Badran, G. Blaylock

The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic Radiation Imaging Telescope Array System) has been in operation since February 2005. We present here a technical description of the instrument and a summary of its performance. The calibration methods are described, along with the results of Monte Carlo simulations of the telescope and

O. Habibi, U. R. Patihnedj, M. O. Dhar

We report the consequences of a destabilization process on a simulated General Purpose Analog Computer. This new technology overcomes problems linked with serial ambiguity, and provides an analog bias to encode algorithms whose complexity is over polynomial. We also implicitly demonstrate how countermesures of the Stochastic Aperture Degeneracy could efficie

M. Argerami, P. Massey

Given a II$_1$ factor M and a masa A of M, we prove a version of the Schur-Horn Theorem, together with a contractive version. These results are inspired on a recent conjecture of Arveson and Kadison (math.OA/0508482).

Mats Holmström

Observations and simulations show that Mars&#39; atmosphere has large seasonal variations. Total atmospheric density can have an order of magnitude latitudinal variation at exobase heights. By numerical simulations we show that these latitude variations in exobase parameters induce asymmetries in the hydrogen exosphere that propagate to large distances from

Douwe Jan Bonthuis, Jingshan Zhang, Breton Hornblower, Jerome Mathe

The current-voltage characteristics of the alpha-Hemolysin protein pore during the passage of single-stranded DNA under varying ionic strength, C, are studied experimentally. We observe strong blockage of the current, weak super-linear growth of the current as a function of voltage, and a minimum of the current as a function of C. These observations are inte

Barbara Drinovec-Drnovsek, Franc Forstneric

We study the existence of topologically closed complex curves normalized by bordered Riemann surfaces in complex spaces. Our main result is that such curves abound in any noncompact complex space admitting an exhaustion function whose Levi form has at least two positive eigenvalues at every point outside a compact set, and this condition is essential. The pr

Paul Mantsch

The Pierre Auger Observatory was designed for a high statistics, full sky study of cosmic rays at the highest energies. Energy, direction and composition measurements are intended to illuminate the mysteries of the most energetic particles in nature. The Auger Observatory utilizes a surface array together with air fluorescence telescopes which together provi

Warren R. Brown, Margaret J. Geller, Scott J. Kenyon, Michael J. Kurtz

We discuss our targeted search for hypervelocity stars (HVSs), stars traveling with velocities so extreme that dynamical ejection from a massive black hole is their only suggested origin. Our survey, now half complete, has successfully identified a total of four probable HVSs plus a number of other unusual objects. Here we report the most recently discovered