February 2010 arXiv papers — page 20

A. Cattaneo, G. A. Mamon, K. Warnick, A. Knebe

We introduce a toy model that describes (in a single equation) the mass in stars as a function of halo mass and redshift. Our model includes the suppression of gas accretion from gravitational shock heating and AGN jets mainly for M_halo > M_shock ~ 10^12 M_Sun and from a too hot IGM onto haloes with v_circ < 40 km/s, as well as stellar feedback that drives

Luis A. Pugnaloni, Iván Sánchez, Paula A. Gago, José Damas

We analyze, experimentally and numerically, the steady states, obtained by tapping, of a 2D granular layer. Contrary to the usual assumption, we show that the reversible (steady state branch) of the density--acceleration curve is nonmonotonous. Accordingly, steady states with the same mean volume can be reached by tapping the system with very different inten

Iwan Schenker, Frank T. Filser, Ludwig J. Gauckler

The recently developed void expansion method (VEM) allows for an efficient generation of porous packings of spherical particles over a wide range of volume fractions. The method is based on a random placement of the structural particles under addition of much smaller &#34;void-particles&#34; whose radii are repeatedly increased during the void expansion. The

C. M. Bender, S. P. Klevansky

An elementary field-theoretic mechanism is proposed that allows one Lagrangian to describe a family of particles having different masses but otherwise similar physical properties. The mechanism relies on the observation that the Dyson-Schwinger equations derived from a Lagrangian can have many different but equally valid solutions. Nonunique solutions to the

Fernando Domínguez, Gloria Platero, Sigmund Kohler

We study electron transport through a triple quantum dot in ring configuration at finite bias. In particular, we analyze the influence of a gate voltage that detunes one of the dots, such that one branch of the interferometer becomes off-resonant. It turns out that then interference effects fade away, i.e., the current becomes independent of a penetrating fl

Osamu Iyama, Idun Reiten

In this paper we investigate the endomorphism algebras of standard cluster tilting objects in the stably 2-Calabi-Yau categories $\Sub{Λ_w}$ with elements $w$ in Coxeter groups in \cite{BIRSc}. They are examples of the 2-Auslander algebras introduced in \cite{I1}. Generalizing work in \cite{GLS1} we show that they are quasihereditary, even strongly quasihere

G. Leloudas, J. Sollerman, A. J. Levan, J. P. U. Fynbo

Aims: We study the distribution of Wolf-Rayet (WR) stars and their subtypes with respect to their host galaxy light distribution. We thus want to investigate whether WR stars are potential progenitors of stripped-envelope core-collapse supernovae (SNe) and/or long-duration gamma-ray bursts (LGRBs). Methods: We derived the relative surface brightness (fractio

M. Toorani

The electronic mail plays an unavoidable role in the humankind communications. With the great interest for the connection via mobile platforms, and the growing number of vulnerabilities and attacks, it is essential to provide suitable security solutions regarding the limitations of resource restricted platforms. Although some solutions such as PGP and S/MIME

M. Toorani, A. A. Beheshti

The GSM network with the greatest worldwide number of users, succumbs to several security vulnerabilities. The short message service (SMS) is one of its superior and well-tried services with a global availability in the GSM networks. The main contribution of this paper is to introduce a new secure application layer protocol, called SSMS, to efficiently embed

Benjamin Piwowarski, Ingo Frommholz, Mounia Lalmas, Keith van Rijsbergen

In Information Retrieval (IR), whether implicitly or explicitly, queries and documents are often represented as vectors. However, it may be more beneficial to consider documents and/or queries as multidimensional objects. Our belief is this would allow building &#34;truly&#34; interactive IR systems, i.e., where interaction is fully incorporated in the IR fr

M. Toorani, A. A. Beheshti

Recently, the mobile industry has experienced an extreme increment in number of its users. The GSM network with the greatest worldwide number of users succumbs to several security vulnerabilities. Although some of its security problems are addressed in its upper generations, there are still many operators using 2G systems. This paper briefly presents the mos

M. C. Amirani, M. Toorani, A. A. Beheshti

File type identification and file type clustering may be difficult tasks that have an increasingly importance in the field of computer and network security. Classical methods of file type detection including considering file extensions and magic bytes can be easily spoofed. Content-based file type detection is a newer way that is taken into account recently.

Pascal Vallet, Philippe Loubaton, Xavier Mestre

We consider the problem of subspace estimation in situations where the number of available snapshots and the observation dimension are comparable in magnitude. In this context, traditional subspace methods tend to fail because the eigenvectors of the sample correlation matrix are heavily biased with respect to the true ones. It has recently been suggested th

Arun Sridharan, C. Emre Koksal, Elif Uysal-Biyikoglu

Information theoretic Broadcast Channels (BC) and Multiple Access Channels (MAC) enable a single node to transmit data simultaneously to multiple nodes, and multiple nodes to transmit data simultaneously to a single node respectively. In this paper, we address the problem of link scheduling in multihop wireless networks containing nodes with BC and MAC capab

J. Bünemann

We introduce a new slave-boson mean-field theory which allows the investigation of general multi-band Hubbard models. Unlike earlier attempts of such a generalisation, in our approach the quantum-mechanical problem is exactly reformulated in an extended Hilbert space of Fermions and Bosons before a mean-field approximation is applied. Systems with supercondu

A. Blasi, N. Maggiore, N. Magnoli, S. Storace

The Maxwell-Chern-Simons (MCS) theory with planar boundary is considered. The boundary is introduced according to Symanzik&#39;s basic principles of locality and separability. A method of investigation is proposed, which, avoiding the straight computation of correlators, is appealing for situations where the computation of propagators, modified by the bounda

H. Nikolic

It is often argued that hypothetic nonlocal reality responsible for nonlocal quantum correlations between entangled particles cannot be consistent with relativity. I review the most frequent arguments of that sort, explain how they can all be circumvented, and present an explicit Bohmian model of nonlocal reality (compatible with quantum phenomena) that full

Daijiro Suematsu, Takashi Toma, Tetsuro Yoshida

The radiative seesaw model with an inert doublet has been shown to be attractive from a viewpoint of both neutrino masses and cold dark matter. However, if we apply this model to the explanation of the positron excess in the cosmic ray observed by PAMELA, a huge boost factor is required although it can be automatically explained that no anti-proton excess ha

Jeroen Keiren, Michel A. Reniers, Tim A. C. Willemse

We analyse the problem of solving Boolean equation systems through the use of structure graphs. The latter are obtained through an elegant set of Plotkin-style deduction rules. Our main contribution is that we show that equation systems with bisimilar structure graphs have the same solution. We show that our work conservatively extends earlier work, conducte

Yong-Su Kim, Hyang-Tag Lim, Young-Sik Ra, Yoon-Ho Kim

We report experimental verification of the commutation relation for Pauli spin operators using quantum interference of the single-photon polarization state. By superposing the quantum operations $σ_z σ_x$ and $σ_x σ_z$ on a single-photon polarization state, we have experimentally implemented the commutator, $[σ_{z}, σ_{x}]$, and the anticommutator, $\{σ_{z},

N. apRoberts-Warren, A. P. Dioguardi, A. C. Shockley, C. H. Lin

CePt$_2$In$_7$ is a new heavy fermion system with a structure similar to the CeMIn$_5$ system but with greater two-dimensional character. We report the synthesis and characterization of phase pure polycrystalline material, which reveals an antiferromagnetic transition at $T_N = 5.2$ K. Nuclear Quadrupolar Resonance (NQR) studies indicate that the antiferroma

Shuai Wei, Isabella Gallino, Ralf Busch, C. Austen Angell

The glass transition GT is usually thought of as a structural arrest that occurs during the cooling of a liquid, or sometimes a plastic crystal, trapping a metastable state of the system before it can recrystallize to stabler forms1. This phenomenon occurs in liquids of all classes, most recently in bulk metallic glassformers2. Much theoretical interest has

E. Harikumar

We derive the Maxwell&#39;s equations on the $κ$-deformed spacetime, valid up to first order in the deformation parameter, using the Feynman&#39;s approach. We show that the electric-magnetic duality is a symmetry of these equations. It is also shown that the laws of electrodynamics are {\it different} for particles of equal charges, but with different masse

Emanuele Delucchi, Aaron Pixton, Lucas Sabalka

Brenti and Welker have shown that for any simplicial complex X, the face vectors of successive barycentric subdivisions of X have roots which converge to fixed values depending only on the dimension of X. We improve and generalize this result here. We begin with an alternative proof based on geometric intuition. We then prove an interesting symmetry of these

Kiyoshi Tamaki, Go Kato

One of the simplest security proofs of quantum key distribution is based on the so-called complementarity scenario, which involves the complementarity control of an actual protocol and a virtual protocol [M. Koashi, e-print arXiv:0704.3661 (2007)]. The existing virtual protocol has a limitation in classical postprocessing, i.e., the syndrome for the error-co

Alexandru Chirvasitu

For a matrix coalgebra $C$ over some field, we determine all small subcoalgebras of the free Hopf algebra on $C$, the free Hopf algebra with a bjective antipode on $C$, and the free Hopf algebra with antipode $S$ satisfying $S^{2d}={\rm id}$ on $C$ for some fixed $d$. We use this information to find the endomorphisms of these free Hopf algebras, and to deter

S. Hamed Hassani, Kasra Alishahi, Rudiger Urbanke

We provide upper and lower bounds on the escape rate of the Bhattacharyya process corresponding to polar codes and transmission over the the binary erasure channel. More precisely, we bound the exponent of the number of sub-channels whose Bhattacharyya constant falls in a fixed interval $[a,b]$. Mathematically this can be stated as bounding the limit $\lim_{

Xiande Yang

An associative ring $R$ with identity is left pseudo-morphic if for every $a$$\in$$R$, there exists $b$$\in$$R$ such that $Ra=l_R(b)$. If, in addition, $l_R(a)=Rb$, then $R$ is called left morphic. $R$ is morphic if it is both left and right morphic. We characterize left pseudo-morphic rings; identify the cases a (left) pseudo morphic ring is (left) quasi-mo

M. D. Birowosuto, S. E. Skipetrov, W. L. Vos, A. P. Mosk

We experimentally study spatial fluctuations of the local density of states (LDOS) inside three-dimensional random photonic media. The LDOS is probed at many positions inside the random photonic media by measuring emission rates of a large number of individual fluorescent nanospheres. The emission rates are observed to fluctuate spatially. We analyze the var

D. Turaev, S. Zelik

We prove that the attractor of the 1D quintic complex Ginzburg-Landau equation with a broken phase symmetry has strictly positive space-time entropy for an open set of parameter values. The result is obtained by studying chaotic oscillations in grids of weakly interacting solitons in a class of Ginzburg-Landau type equations. We provide an analytic proof for

S. A. Farrell, M. Servillat, S. R. Oates, I. Heywood

The brightest Ultra-Luminous X-ray source HLX-1 in the galaxy ESO 243-49 currently provides strong evidence for the existence of intermediate mass black holes. Here we present the latest multi-wavelength results on this intriguing source in X-ray, UV and radio bands. We have refined the X-ray position to sub-arcsecond accuracy. We also report the detection o

Pierre-François Loos, Peter M. W. Gill

We consider the high-density-limit correlation energy $\Ec$ in $D \ge 2$ dimensions for the $^1S$ ground states of three two-electron systems: helium (in which the electrons move in a Coulombic field), spherium (in which they move on the surface of a sphere), and hookium (in which they move in a quadratic potential). We find that the $\Ec$ values are strikin

G. M. Williger, R. F. Carswell, R. J. Weymann, E. B. Jenkins

We present an analysis of the Ly-a forest toward 3C 273 from the Space Telescope Imaging Spectrograph at ~7 km/s resolution, along with re-processed data from the Far Ultraviolet Spectroscopic Explorer. The high UV flux of 3C 273 allows us to probe the weak, low z absorbers. The main sample consists of 21 HI absorbers that we could discriminate to a sensitiv

Pierre-François Loos, Peter M. W. Gill

We show that the exact wave function for two electrons, interacting through a Coulomb potential but constrained to remain on the surface of a $\mathcal{D}$-sphere ($\mathcal{D} \ge 1$), is a polynomial in the interelectronic distance $u$ for a countably infinite set of values of the radius $R$. A selection of these radii, and the associated energies, are rep

Pierre-François Loos, Peter M. W. Gill

We have performed a comprehensive study of the singlet ground state of two electrons on the surface of a sphere of radius $R$. We have used electronic structure models ranging from restricted and unrestricted Hartree-Fock theory to explicitly correlated treatments, the last of which lead to near-exact wavefunctions and energies for any value of $R$. Møller-P

Hirohito Aizawa, Kazuhiko Kuroki, Harukazu Yoshino, Keizo Murata

We study the origin of the large thermopower in quasi-two-dimensional a $τ$-type organic conductor, $τ-(EDO-S,S-DMEDT-TTF)_2(AuBr_2)_{1+y}$ ($y \le 0.875$), from the view point of a &#34;pudding mold&#34;-type band structure. We calculate the electronic band structure using an \textit{ab initio} band calculation package, and obtain a tight binding model fit

H. Yoshino, H. Aizawa, K. Kuroki, G. C. Anyfantis

Dimensionless thermoelectric figure of merit $ZT$ is investigated for two-dimensional organic conductors $τ-(EDO-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$, $τ$-(EDT-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$ and $τ$-(P-S,S-DMEDT-TTF)_2(AuI_2)_{1+y}$ ($y \le 0.875$), respectively. The $ZT$ values were estimated by measuring electrical resistivity, thermopower and thermal conductivi

Francesco Shankar, Federico Marulli, Mariangela Bernardi, Michael Boylan-Kolchin

We discuss how the effective radius Phi(Re) function (ERF) recently worked out by Bernardi et al. (2009) represents a new testbed to improve the current understanding of Semi-analytic Models of Galaxy formation. In particular, we here show that a detailed hierarchical model of structure formation can broadly reproduce the correct peak in the size distributio

V. G. Kogan

Following the work of Abrikosov and Gor&#39;kov on the pair-breaking effects, one can derive the temperature dependencies of the electronic specific heat $C_s/T=γ^\prime+μT^2$ (with the jump at the superconducting transition $ΔC \propto T_c^3$) for materials with zero Fermi surface average of the order parameter $<Δ>=0$ (e.g. d-wave) or for those with $<Δ> \

A. Sagnotti

The simplest higher-spin interactions involve classical external currents and symmetric tensors $ϕ_{\m_1 ... \m_s}$, and convey three instructive lessons. The first is a general form of the van Dam-Veltman-Zakharov discontinuity in flat space for this class of fields. The second is the rationale for its disappearance in (A)dS spaces. Finally, the third is a

Avner Ash, Paul E. Gunnells, Mark McConnell

We report on the computation of torsion in certain homology theories of congruence subgroups of SL(4,Z). Among these are the usual group cohomology, the Tate-Farrell cohomology, and the homology of the sharbly complex. All of these theories yield Hecke modules. We conjecture that the Hecke eigenclasses in these theories have attached Galois representations.

Anh-Thu Le, R. R. Lucchese, C. D. Lin

We present theoretical calculations for polarization and ellipticity of high-order harmonics from aligned N$_2$, CO$_2$, and O$_2$ molecules generated by linearly polarized lasers. Within the rescattering model, the two polarization amplitudes of the harmonics are determined by the photo-recombination amplitudes for photons emitted parallel and perpendicular

Yong Zeng, Qi Wu, Douglas H. Werner

In this Letter, we develop an electrostatic theory for designing bulk composites with effective lossless negative permittivities. The theory and associated design procedure are validated by comparing their predictions with those of rigorous full-wave simulations. It is demonstrated that the excitation of the Frohlich mode (the first-order surface mode) of th

Helmut Hofer, Kris Wysocki, Eduard Zehnder

We survey a (nonlinear) Fredholm theory for a new class of ambient spaces called polyfolds, and develop the analytical foundations for some of the applications of the theory. The basic feature of these new spaces, which can be finite and infinite dimensional, is that in general they may have locally varying dimensions. These new spaces are needed for a funct

Kelly Holley-Bockelmann, Miroslav Micic, Steinn Sigurdsson, Louis Rubbo

We calculate the gravitational wave signal from the growth of 10 million solar mass supermassive black holes (SMBH) from the remnants of Population III stars. The assembly of these lower mass black holes is particularly important because observing SMBHs in this mass range is one of the primary science goals for the Laser Interferometer Space Antenna (LISA),

G. Ghisellini, G. Ghirlanda

The GeV emission of Gamma Ray Bursts, first detected by EGRET in an handful of bursts, is now an established property of roughly the 10% of all bursts, thanks to the Fermi/LAT observations. GRB 090510, a short burst, is particularly interesting because the good timing allows to derive a severe limit to theories of quantum gravity. With the dozen bursts detec

Yan Qu, Paola Di Matteo, Matthew Lehnert, Wim van Driel

We have investigated the impact of dissipationless minor galaxy mergers on the angular momentum of the remnant. Our simulations cover a range of initial orbital characteristics and the system consists of a massive galaxy with a bulge and disk merging with a much less massive (one-tenth or one-twentieth) gasless companion which has a variety of morphologies (

Brent Groves, Mark Allen

We present a new software tool to enable astronomers to easily compare observations of emission line ratios with those determined by photoionization and shock models, ITERA, the IDL Tool for Emission-line Ratio Analysis. This tool can plot ratios of emission lines predicted by models and allows for comparison of observed line ratios against grids of these mo

M. Santiago-Cortes, Y. D. Mayya, D. Rosa-Gonzalez

We study the population of compact stellar clusters (CSCs) in M81, using the HST/ACS images in the filters F435W, F606W and F814W covering, for the first time, the entire optical extent of the galaxy. Our sample contains 435 clusters of FWHM less than 10 ACS pixels (9 pc). The sample shows the presence of two cluster populations, a blue group of 263 objects

Iver B. Sperstad, Einar B. Stiansen, Asle Sudbo

The dynamical critical exponent $z$ is a fundamental quantity in characterizing quantum criticality, and it is well known that the presence of dissipation in a quantum model has significant impact on the value of $z$. Studying quantum Ising spin models using Monte Carlo methods, we estimate the dynamical critical exponent $z$ and the correlation length expon

Evelyn Sander, James A. Yorke

The appearance of infinitely-many period-doubling cascades is one of the most prominent features observed in the study of maps depending on a parameter. They are associated with chaotic behavior, since bifurcation diagrams of a map with a parameter often reveal a complicated intermingling of period-doubling cascades and chaos. Period doubling can be studied

Marat Gilfanov, Akos Bogdan

There is wide agreement that Type Ia supernovae (used as standard candles for cosmology) are associated with the thermonuclear explosions of white dwarf stars. The nuclear runaway that leads to the explosion could start in a white dwarf gradually accumulating matter from a companion star until it reaches the Chandrasekhar limit, or could be triggered by the

Patrick Marsch, Gerhard Fettweis

Coordinated Multi-Point (CoMP) is known to be a key technology for next generation mobile communications systems, as it allows to overcome the burden of inter-cell interference. Especially in the uplink, it is likely that interference exploitation schemes will be used in the near future, as they can be used with legacy terminals and require no or little chan

Akos Bogdan, Marat Gilfanov

We aim to place upper limits on the combined X-ray emission from the population of steady nuclear-burning white dwarfs in galaxies. In the framework of the single-degenerate scenario these systems are believed to be likely progenitors of Type Ia supernovae. From the Chandra archive, we selected normal early-type galaxies with the point source detection sensi

Akos Bogdan, Marat Gilfanov

We investigate unresolved X-ray emission from M31 based on an extensive set of archival XMM-Newton and Chandra data. We show that extended emission, found previously in the bulge and thought to be associated with a large number of faint compact sources, extends to the disk of the galaxy with similar X-ray to K-band luminosity ratio. We also detect excess X-r

Taras Banakh, Olena Hryniv

We prove that for a complete quasivariety $K$ of topological $E$-algebras of countable discrete signature $E$ and each submetrizable $ANR(k_ω)$-space $X$ its free topological $E$-algebra $F_K(X)$ in the class $K$ is a submetrizable $ANR(k_ω)$-space.

N. G. Mensah

Surface (2D) acoustomagnetoelectric effect (SAME) and bulk (3D) acoustomagnetoelectric effect (AME) have been studied in a degenerate semiconductor with nonparabolic energy dispersion law. Expressions are obtained for the acoustomagnetoelectric fields i.e. SAME E and AME E under weak wt <<1 and strong (wt >>1) magnetic fields. It is shown that SAME E and AME

D. K. Pratt, A. Kreyssig, S. Nandi, N. Ni

Inelastic neutron scattering measurements have been performed on underdoped Ba(Fe1-xCox)2As2 (x = 4.7%) where superconductivity and long-range antiferromagnetic (AFM) order coexist. The broad magnetic spectrum found in the normal state develops into a magnetic resonance feature below TC that has appreciable dispersion along c-axis with a bandwidth of 3-4 meV

Giulia Pagliaroli, Fernando Rossi-Torres, Francesco Vissani

Based on recent improvements of the supernova electron antineutrino emission model, we update the limit on neutrino mass from the SN1987A data collected by Kamiokande-II, IMB and Baksan. We derive the limit of 5.8 eV at 95 % CL, that we show to be remarkably insensitive to the astrophysical uncertainties. Also we evaluate the ultimate mass sensitivity of thi

S. Elhandi, S. Taj, Y. attaourti, B. Manaut

The effect of the electron&#39;s anomalous magnetic moment on the relativistic electronic dressing for the process of electron-hydrogen atom elastic collisions is investigated. We consider a laser field with circular polarization and various electric field strengths. The Dirac-Volkov states taking into account this anomaly are used to describe the process in

Alireza Avanaki

The SSIM-optimized exact global histogram specification (EGHS) is shown to converge in the sense that the first order approximation of the result&#39;s quality (i.e., its structural similarity with input) does not decrease in an iteration, when the step size is small. Each iteration is composed of SSIM gradient ascent and basic EGHS with the specified target

Harvey B. Meyer

We investigate the thermal correlator of the trace of the energy-momentum tensor in the SU(3) Yang-Mills theory. Our goal is to constrain the spectral function in that channel, whose low-frequency part determines the bulk viscosity. We focus on the thermal modification of the spectral function, $ρ(ω,T)-ρ(ω,0)$. Using the operator-product expansion we give th

B. Georgeot, O. Giraud, D. L. Shepelyansky

We study numerically the spectrum and eigenstate properties of the Google matrix of various examples of directed networks such as vocabulary networks of dictionaries and university World Wide Web networks. The spectra have gapless structure in the vicinity of the maximal eigenvalue for Google damping parameter $α$ equal to unity. The vocabulary networks have

S. N. Singh, A. K. Singh

With the increasing concern about global environmental protection and energy demand due to rapid growth of population in developing countries and the diminishing trend of resources of conventional grid supply, the need to produce freely available pollution free natural energy such as solar/wind energy has been drawing increasing interest in every corner of t

Ha-ryong Song, Vladimir Shin

This paper is concerned with distributed limited memory prediction for continuous-time linear stochastic systems with multiple sensors. A distributed fusion with the weighted sum structure is applied to the optimal local limited memory predictors. The distributed prediction algorithm represents the optimal linear fusion by weighting matrices under the minimu

Asok De, N. S. Raghava, Sagar Malhotra, Pushkar Arora

Selection of the most suitable substrate for a Microstrip antenna is a matter of prime importance. This is because many limitations of the microstrip antenna such as high return loss, low gain and low efficiency can be overcome by selecting an appropriate substrate for fabrication of the antenna, without shifting the resonant frequency significantly. The sub

Daniel Lecoanet, Ellen G. Zweibel, Richard H. D. Townsend, Yi-Min Huang

Shear flow instabilities can profoundly affect the diffusion of momentum in jets, stars, and disks. The Richardson criterion gives a sufficient condition for instability of a shear flow in a stratified medium. The velocity gradient $V&#39;$ can only destabilize a stably stratified medium with squared Brunt-Vaisala frequency $N^2$ if $V&#39;^2/4>N^2$. We find

M. S. Clemens, A. Scaife, O. Vega, A. Bressan

We describe radio observations at 244 and 610 MHz of a sample of 20 luminous and ultra-luminous IRAS galaxies. These are a sub-set of a sample of 31 objects that have well-measured radio spectra up to at least 23 GHz. The radio spectra of these objects below 1.4 GHz show a great variety of forms and are rarely a simple power-law extrapolation of the synchrot

Ijaj Md. Laisuzzaman, Nahid Imran, Abdullah Al Nahid, Md. Ziaul

In this paper, we describe an effective framework for adapting electronic commerce or e-commerce services in developing countries like Bangladesh. The internet has opened up a new horizon for commerce, namely electronic commerce (e-commerce). It entails the use of the internet in the marketing, identification, payment and delivery of goods and services. At p

Sargam Parmar, Bhuvan Unhelkar

Commercial cellular networks, like the systems based on DS-CDMA, face many types of interferences such as multi-user interference inside each sector in a cell to interoperate interference. Independent Component Analysis (ICA) has been used as an advanced preprocessing tool for blind suppression of interfering signals in DS-CDMA communication systems. The rol

Andrew Goodall, Anna de Mier

Masbaum and Vaintrob&#39;s &#34;Pfaffian matrix tree theorem&#34; implies that counting spanning trees of a 3-uniform hypergraph (abbreviated to 3-graph) can be done in polynomial time for a class of &#34;3-Pfaffian&#34; 3-graphs, comparable to and related to the class of Pfaffian graphs. We prove a complexity result for recognizing a 3-Pfaffian 3-graph and

M. Tarighi, S. A. Motamedi, S. Sharifian

In this paper, we show that performance of the virtualized cluster servers could be improved through intelligent decision over migration time of Virtual Machines across heterogeneous physical nodes of a cluster server. The cluster serves a variety range of services from Web Service to File Service. Some of them are CPU-Intensive while others are RAM-Intensiv

Md. M. Hossain, J. Hossain

One of the biggest drawbacks of the wireless environment is the limited bandwidth. However, the users sharing this limited bandwidth have been increasing considerably.Space Division Multiple Access (SDMA) is a new technology by which the capacity of existing mobile communication systems can economically be increased. This paper has been presented how the cap

Zach Medin, Andrew Cumming

We develop a method for calculating the equilibrium properties of the liquid-solid phase transition in a classical, ideal, multi-component plasma. Our method is a semi-analytic calculation that relies on extending the accurate fitting formulae available for the one-, two-, and three-component plasmas to the case of a plasma with an arbitrary number of compon

Boris S. Verkhovsky

Topological design of terrestrial networks for communication via satellites is studied in the paper. Quantitative model of the network cost-analysis minimizing the total transmission and switching cost is described. Several algorithms solving combinatorial problem of the optimal topology design based on binary partitioning, a minimax parametric search and dy

A. F. Rappazzo, M. Velli, G. Einaudi, R. B. Dahlburg

The plasma density enhancements recently observed by the Large-Angle Spectrometric Coronagraph (LASCO) instrument onboard the Solar and Heliospheric Observatory (SOHO) spacecraft have sparked considerable interest. In our previous theoretical study of the formation and initial motion of these density enhancements it is found that beyond the helmet cusp of a

S. C. Gallagher, P. R. Durrell, D. M. Elmegreen, R. Chandar

The handful of low-mass, late-type galaxies that comprise Hickson Compact Group 31 is in the midst of complex, ongoing gravitational interactions, evocative of the process of hierarchical structure formation at higher redshifts. With sensitive, multicolor Hubble Space Telescope imaging, we characterize the large population of <10 Myr old star clusters that s

M. A. Alhabeeb, A. M Almuhaideb, P. D Le

Denial of service attacks (DoS) can cause significant financial damages. Flooding and Malicious packets are two kinds of DoS attacks. This paper presents a new security approach which stops malicious packets and prevents flooding in the critical systems. New concepts of packet stamp a dynamic-multi-communication-point mechanism has been identified for this p

A. Ciattoni, C. Rizza, E. Palange

We consider a sub-wavelength periodic layered medium whose slabs are filled by arbitrary linear metamaterials and standard nonlinear Kerr media and we show that the homogenized medium behaves as a Kerr medium whose parameters can assume values not available in standard materials. Exploiting such a parameter availability, we focus on the situation where the l

Raungrong Suleesathira

Combined with space-time coding, the orthogonal frequency division multiplexing (OFDM) system explores space diversity. It is a potential scheme to offer spectral efficiency and robust high data rate transmissions over frequency-selective fading channel. However, space-time coding impairs the system ability to suppress interferences as the signals transmitte

Haozhao Liang, Wen Hui Long, Jie Meng, Nguyen Van Giai

The spin symmetry in the Dirac negative energy spectrum and its origin are investigated for the first time within the density-dependent relativistic Hartree-Fock (DDRHF) theory. Taking the nucleus $^{16}$O as an example, the spin symmetry in the negative energy spectrum is found to be a good approximation and the dominant components of the Dirac wave functio

Steffen Schreiber, Thomas Fischer, Walter Zimmermann

At low Reynolds numbers, the hydrodynamic interaction between dumbbells driven by an external rotating field can be attractive or repulsive. Dumbbells of dissimilar asymmetric shape or different coupling to the external field undergo conformational rearrangements that break the time reversal symmetry. The parameter ranges leading to attraction or repulsion a

Yusuke Watanabe, Kenji Fukumizu

We propose a new approach to the analysis of Loopy Belief Propagation (LBP) by establishing a formula that connects the Hessian of the Bethe free energy with the edge zeta function. The formula has a number of theoretical implications on LBP. It is applied to give a sufficient condition that the Hessian of the Bethe free energy is positive definite, which sh

Robert C. Helling, Wolfgang Spitzer

We show that the entanglement entropy associated to a region grows faster than the area of its boundary surface. This is done by proving a special case of a conjecture due to Widom that yields a surprisingly simple expression for the leading behaviour of the entanglement entropy.

T. Straus, B. Fleck, S. M. Jefferies, M. Carlsson

In our studies of the dynamics and energetics of the solar atmosphere, we have detected, in high-quality observations from Hinode SOT/NFI, ubiquitous small-scale upflows which move horizontally with supersonic velocities in the quiet Sun. We present the properties of these fast moving upflows (FMUs) and discuss different interpretations.

Martin Reiris

We discuss a set of relations, set in the form of results, conjectures and problems, between the L^{2}-norm of the Ricci curvature of a 3-manifold, the scalar curvature and the volume radius. We illustrate the scope of these relations with potential applications to the Einstein Constant Mean Curvature flow (or GR seen as a geometric flow of constant mean cur

A. P. Misra, S. Banerjee, F. Haas, P. K. Shukla

The temporal dynamics of the quantum Zakharov equations (QZEs) in one spatial dimension, which describes the nonlinear interaction of quantum Langmuir waves (QLWs) and quantum ion-acoustic waves (QIAWs) is revisited by considering their solution as a superposition of three interacting wave modes in Fourier space. Previous results in the literature are modifi

J. B. R. Oonk, W. Jaffe, M. N. Bremer, R. J. van Weeren

We have used the SINFONI integral field spectrograph to map the near-infrared K-band emission lines of molecular and ionised hydrogen in the central regions of two cool core galaxy clusters, Abell 2597 and Sersic 159-03. Gas is detected out to 20 kpc from the nuclei of the brightest cluster galaxies and found to be distributed in clumps and filaments around

Neil Smith, Matthew J. Carey, Jeffrey R. Childress

In-situ, device level measurement of thermal mag-noise spectral linewidths in 60nm diameter CPP-GMR spin-valve stacks of IrMn/ref/Cu/free, with reference and free layer of similar CoFe/CoFeGe alloy, are used to simultaneously determine the intrinsic Gilbert damping for both magnetic layers. It is shown that careful alignment at a &#34;magic-angle&#34; betwee

Boris Aronov, Otfried Cheong, Xavier Goaoc, Günter Rote

A line g is a transversal to a family F of convex polytopes in 3-dimensional space if it intersects every member of F. If, in addition, g is an isolated point of the space of line transversals to F, we say that F is a pinning of g. We show that any minimal pinning of a line by convex polytopes such that no face of a polytope is coplanar with the line has siz

Robert Ehrlich

Evidence is provided that the global distribution of tropical hurricanes is principally determined by a universal function H of a single variable z that in turn is expressible in terms of the local sea surface temperature and latitude. The data-driven model presented here carries stark implications for the large increased numbers of hurricanes which it predi

Vasileios Maroulas

Uniform large deviation principles for positive functionals of all equivalent types of infinite dimensional Brownian motions acting together with a Poisson random measure are established. The core of our approach is a variational representation formula which for an infinite sequence of i.i.d real Brownian motions and a Poisson random measure was shown in [5]

Douglas Ulmer

This is a survey article written for a workshop on L-functions and random matrix theory at the Newton Institute in July, 2004. The goal is to give some insight into how well-distributed sets of matrices in classical groups arise from families of $L$-functions in the context of function fields of curves over finite fields. The exposition is informal and no pr

A. Gurevich

It is shown that the electric charge of vortices can result in a helical instability of straight vortex lines in layered superconductors, particularly Bi-based cuprates or organic superconductors. This instability may result in a phase transition to a uniformly twisted vortex state, which could be detected by torque magnetometry, neutron diffraction, electro

M. L. Nesterov, D. Martin-Cano, A. I. Fernandez-Dominguez, E. Moreno

We demonstrate that the introduction of a subwavelength periodic modulation into a metallic structure strongly modifies the guiding characteristics of the surface plasmon modes supported by the system. Moreover, it is also shown how a new type of a tightly confined surface plasmon polariton mode can be created by just milling a periodic corrugation into a me

Samuel Johnson, Joaquin J. Torres, J. Marro, Miguel A. Munoz

Why are most empirical networks, with the prominent exception of social ones, generically degree-degree anticorrelated, i.e. disassortative? With a view to answering this long-standing question, we define a general class of degree-degree correlated networks and obtain the associated Shannon entropy as a function of parameters. It turns out that the maximum e

B. Fleck, T. Straus, M. Carlsson, S. M. Jefferies

The present study addresses the following questions: How representative of the actual velocities in the solar atmosphere are the Doppler shifts of spectral lines? How reliable is the velocity signal derived from narrowband filtergrams? How well defined is the height of the measured Doppler signal? Why do phase difference spectra always pull to 0 degrees phas

H. S. Borges, L. Sanz, J. M. Villas-Boas, A. M. Alcalde

Semiconductor quantum dots coherently driven by pulsed laser are fundamental physical systems which allow studying the dynamical properties of confined quantum states. These systems are attractive candidates for a solid-state qubit, which open the possibility for several investigations in quantum information processing. In this work we study the effects of a

Duc-Manh Nguyen

Flat surfaces with erasing forest are obtained by deforming the flat metric structure of translation surfaces, the moduli space of such surfaces is a deformation of the moduli space of translation surfaces. On the moduli space of flat surfaces with erasing forest, one can define some energy function involving the area of the surface, and the total length of

Skip Garibaldi, Holger P. Petersson

The epicenter of this paper concerns Pfister quadratic forms over a field $F$ with a Henselian discrete valuation. All characteristics are considered but we focus on the most complicated case where the residue field has characteristic 2 but $F$ does not. We also prove results about round quadratic forms, composition algebras, generalizations of composition a