September 2007 arXiv papers — page 31

Jian-Wu Wu, Chun-Wen Li, Jing Zhang, Tzyh-Jong Tarn

This paper discusses the energy optimal control problem for the class of quantum systems that possess dynamical symmetry of SU(1,1), which are widely studied in various physical problems in the quantum theory. Based on the maximum principle on Lie group, the complete set of optimal controls are analytically obtained, including both normal and abnormal extrem

Sujatha Ramachandran, Robert H. Blick, Daniel W. van der Weide

We present measurements on direct radio-frequency pumping of ion channels and pores bound in bilipid membranes. We make use of newly developed microcoaxes, which allow delivering the high frequency signal in close proximity to the membrane bound proteins and ion channels. We find rectification of the radio-frequency signal, which is used to pump ions through

M. Molina, M. Giroletti, A. Malizia, R. Landi

In this paper we present radio and high energy observations of the INTEGRAL source IGR J21247+5058, a broad line emitting galaxy obscured by the Galactic plane. Archival VLA radio data indicate that IGR J21247+5058 can be classified as an FRII Broad Line Radio Galaxy. The spectrum between 610 MHz and 15 GHz is typical of synchrotron self-absorbed radiation w

Abdelhak Djouadi, Joseph Lykken, Klaus Mönig, Yasuhiro Okada

This article reviews the physics case for the ILC. Baseline running at 500 GeV as well as possible upgrades and options are discussed. The opportunities on Standard Model physics, Higgs physics, Supersymmetry and alternative theories beyond the Standard Model are described.

Hal Schenck, Stefan O. Tohaneanu

Let ${\mathcal C}= \bigcup_{i=1}^n C_i \subseteq \mathbb{P}^2$ be a collection of smooth rational plane curves. We prove that the addition-deletion operation used in the study of hyperplane arrangements has an extension which works for a large class of arrangements of smooth rational curves, giving an inductive tool for understanding the freeness of the modu

A. Morriss-Andrews, R. J. Gooding

An anisotropic t-J-U model Hamiltonian is used to model electron behaviour in quasi-2d materials in the dilute limit, and as a highly simplified representation of the weakly coupled CuO2 planes of the high-Tc cuprates we model the very poor out-of-plane conductivity via the complete suppression of interplanar hopping. However, we do include the very weak int

M. L. Pretorius, C. Knigge, D. O'Donoghue, J. P. Henry

We use the ROSAT North Ecliptic Pole (NEP) survey to construct a small, but purely X-ray flux-limited sample of cataclysmic variable stars (CVs). The sample includes only 4 systems, 2 of which (RX J1715.6+6856 and RX J1831.7+6511) are new discoveries. We present time-resolved spectroscopy of the new CVs and measure orbital periods of 1.64 \pm 0.02 h and 4.01

Raphael Hirschi, Cristina Chiappini, Georges Meynet, Sylvia Ekstrom

Mass loss plays a dominant role in the evolution of massive stars at solar metallicity. After discussing different mass loss mechanisms and their metallicity dependence, we present the possibility of strong mass loss at very low metallicity. Our models at Z=1e-8 show that stars more massive than about 60 solar masses may lose a significant fraction of their

Andre M. C. Souza, Hans Herrmann

The local electronic structure on nanoscale chains is investigated theoretically. We propose a mechanism to explain the even-odd oscillation of length distribution of atom chains. We study the spatial peak structure as obtained by scanning tunneling microscopy (STM) constant-current topography as a function of the electron-electron interaction, band filling

Won Kyung Seong, Ji Yeong Huh, Won Nam Kang, Jeong-Woon Kim

Epitaxial MgB2 thick films were grown on Al2O3 substrates at 600 oC by using the hybrid physical chemical vapor deposition (HPCVD) technique. In order to obtain a high magnesium vapor pressure around the substrates, we used a special susceptor having a susceptor cap and achieved a very high growth rate of 0.17 um/min. Hexgonal-shaped columnar structures were

L. B. Lucy

Following procedures pioneered by Castor, Abbott & Klein (1975, [CAK]), spherically-symmetric supersonic winds for O stars are computed for matching to plane-parallel moving reversing layers (RL's) from Paper I (Lucy 2007). In contrast to a CAK wind, each of these solutions is singularity-free, thus allowing its mass-loss rate to be fixed by the regulari

M. Persic, A. DeAngelis, F. Longo, M. Tavani

We describe the emission properties of blazars, i.e. the AGNs that, due to their peculiar orientation w.r.t. the observer, allow the most penetrating and direct view of their central engine. After showing that the extragalactic GeV-TeV sky is dominated by blazars of various types, we discuss the kind of blazars that are likely to be jointly detected by AGILE

Y. Osone

We will describe the thermal performance of power semiconductor module, which consists of hetero-junction bipolar transistors (HBTs), for mobile communication systems. We calculate the thermal resistance between the HBT fingers and the bottom surface of a multi-layer printed circuit board (PCB) using a finite element method (FEM). We applied a steady state a

Y. Lai, N. Cordero, F. Barthel, F. Tebbe

With the advances in the technology of materials based on GaN, high brightness white light emitting diodes (LEDs) have flourished over the past few years and have shown to be very promising in many new illumination applications such as outdoor illumination, task and decorative lighting as well as aircraft and automobile illuminations. The objective of this p

N. Neumayer, M. Cappellari, J. Reunanen, H. -W. Rix

We present two-dimensional gas-kinematic maps of the central region in Centaurus A. The adaptive optics (AO) assisted SINFONI data from the VLT have a resolution of 0.12" in K-band. The ionized gas species (Br_gamma, [FeII], [SiVI]) show a rotational pattern that is increasingly overlaid by non-rotational motion for higher excitation lines in direction o

A. Dozolme, H. Metwally, T. Marchal

Using the finite volume CFD software FLUENT, one fan was studied at a given flow rate (1.5m3/min) for three different operational rotating speeds : 2,000, 2,350 and 2,700 rpm. The turbulent air flow analysis predicts the acoustic behavior of the fan. The best fan operating window, i.e. the one giving the best ratio between noise emissions and cooling perform

G. Mura, G. Cassanelli

Starting from two case histories, where only after thorough Failure Analysis the suddenly appearance of a failure was linked to much earlier events, the possibility of improving the reliability and of adjusting the reliability prediction tools are discussed.

Cheong Xin Chan, Robert G. Beiko, Mark A. Ragan

Genetic recombination can produce heterogeneous phylogenetic histories within a set of homologous genes. Delineating recombination events is important in the study of molecular evolution, as inference of such events provides a clearer picture of the phylogenetic relationships among different gene sequences or genomes. Nevertheless, detecting recombination ev

D. Szente-Varga, Gy. Horvath, M. Rencz

In this paper the methodology and the results of creating temperature dependent battery models for ambient intelligence applications is presented. First the measurement technology and the model generation process is presented in details, and then the characteristic features of the models are discussed.

S. Kondo, Qiang Yu, T. Shibutani, M. Shiratori

The recent development of electric and electronic devices has been remarkable. The miniaturization of electronic devices and high integration are progressing by advances in mounting technology. As a result, the reliability of fatigue life has been prioritized as an important concern, since the thermal expansion difference between a package and printed circui

D. Benoy

This paper presents a study of accuracy issues in thermal modeling of high power LED modules on system level. Both physical as well as numerical accuracy issues are addressed. Incorrect physical assumptions may result in seemingly correct, but erroneous results. It is therefore important to motivate the underlying key physical assumptions of a thermal model.

Z. Suszynski, R. Duer, M. Kosikowski

This paper presents the consideration of the presence and the influence of non-linear distortion of photo-acoustic measurement set-up on the results of thermal properties analysis for the multi-layer semiconductor structure. The authors propose a method which will eliminate such an influence.

C. Sapia

The aim of this work is to develop a simple optical method for the visualization of the natural convection flow generated in an electronic system during its normal operation. The presented experimental set-up allows to reveal local refractive index changes in a phase objects. A fringe pattern is acquired, through the cooling fluid under analysis, with a digi

J. Das, H. Oprins, H. Ji, A. Sarua

Galliumnitride has become a strategic superior material for space, defense and civil applications, primarily for power amplification at RF and mm-wave frequencies. For AlGaN/GaN high electron mobility transistors (HEMT), an outstanding performance combined together with low cost and high flexibility can be obtained using a System-in-a-Package (SIP) approach.

Z. Suszynski, M. Kosikowski, R. Duer

In this paper, the solution of the problem of identification of thermal properties of investigated multi-layer structure is presented. In order of that, artificial neural network was used to find the set of thermal properties for which the complex contrast characteric derived fits the best to the one evaluated basing upon experimenatal data.

L. Pohl, V. Szekely

The high dissipation of integrated circuits means serious problems for packaging and for the design of complex electronic systems. Another important area of research and development nowadays is the integration of sensors and micromechanical systems (MEMS) with electronic circuits. The original Successive Node Reduction (SUNRED) algorithm handles well the fir

E. Kollár, V. Szekely

The thermal response function given to a unit-step dissipation accurately characterizes the thermal system. Instead of the thermal response function the so-called structure function describing three-dimensional as the equivalent model of one-dimensional heat-spreading, created from the thermal response function with the help of complex mathematical procedure

D. Jarecka, J. Kalinowski, S. F. King, J. P. Roberts

The neutralino sector of the U(1) extended SUSY is presented and some collider and cosmology-related phenomenology discussed.

E. Rotem, J. Hermerding, A. Cohen, H. Cain

Modern CPUs with increasing core frequency and power are rapidly reaching a point where the CPU frequency and performance are limited by the amount of heat that can be extracted by the cooling technology. In mobile environment, this issue is becoming more apparent, as form factors become thinner and lighter. Often, mobile platforms trade CPU performance in o

Q. Yu, T. Shibutani, M. Shiratori, T. Matsuzaki

In recent years, interfacial fracture becomes one of the most important problems in the assessment of reliability of electronics packaging. Especially, underfill resin is used with solder joints in flip chip packaging for preventing the thermal fatigue fracture in solder joints. In general, the interfacial strength has been evaluated on the basis of interfac

D. Hennig, S. Fugmann, L. Schimansky-Geier, P. Hänggi

We present the noise free escape of a chain of linearly interacting units from a metastable state over a cubic on-site potential barrier. The underlying dynamics is conservative and purely deterministic. The mutual interplay between nonlinearity and harmonic interactions causes an initially uniform lattice state to become unstable, leading to an energy redis

C. A. Stephan

Gauge unification is widely considered to be a desirable feature for extensions of the standard model. Unfortunately the standard model itself does not exhibit a unification of its running gauge couplings but it is required by grand unified theories as well as the noncommutative version of the standard model [2]. We will consider here the extension of the no

J. Tzuo-Sheng Tsai, H. Chiueh

High linear voltage references circuitry are designed and implemented in TSMC 0.18$μ$m CMOS technology. Previous research has proposed the use of MOS transistors operating in the weak inversion region to replace the bipolar devices in conventional PTAT(proportional to absolute temperature) circuits. However such solutions often have linearity problem in high

C. -I. Björnsson

The optical-UV component in GRB 060218 is assumed to be due to optically thick cyclotron emission. The key aspect of this model is the high temperature of the absorbing electrons. The heat input derives from nuclei accelerated in semi-relativistic internal shocks, like in ordinary gamma-ray bursts. Coulomb collisions transfer part of that energy to electrons

P. -L. Komarov, M. G. Burzo, P. -E. Raad

This work introduces a thermoreflectance-based system designed to measure the surface temperature field of activated microelectronic devices at submicron spatial resolution with either a laser or a CCD camera. The article describes the system, outlines the measurement methodology, and presents validation results. The thermo-reflectance thermography (TRTG) sy

Masahito Kubo, Kiyoshi Ichimoto, Toshifumi Shimizu, Saku Tsuneta

Vector magnetic fields of moving magnetic features (MMFs) are well observed with the Solar Optical Telescope (SOT) aboard the Hinode satellite. We focus on the evolution of three MMFs with the SOT in this study. We found that an MMF having relatively vertical fields with polarity same as the sunspot is detached from the penumbra around the granules appeared

D. Schweitzer

This paper presents a very straightforward method to compute the transient thermal response to arbitrary power dissipation profiles in electronic devices with multiple heat sources. Using cubic spline interpolation of simulated or measured unit power step response curves (Zth-functions), additional errors due to model reduction can be avoided. No effort has

Peter E. Raad, Pavel L. Komarov, M. Burzo

This work builds on the previous introduction [1] of a coupled experimental-computational system devised to fully characterize the thermal behavior of complex 3D submicron electronic devices. The new system replaces the laser-based surface temperature scanning approach with a CCD camera-based approach. As before, the thermo-reflectance thermography system is

T. Kemper, Y. Zhang, Z. Bian, A. Shakouri

One of the crucial steps in the design of an integrated circuit is the minimization of heating and temperature non-uniformity. Current temperature calculation methods, such as finite element analysis and resistor networks have considerable computation times, making them incompatible for use in routing and placement optimization algorithms. In an effort to re

R. Schacht, D. May, B. Wunderle, O. Wittler

In this paper new characterization equipment for thermal interface materials is presented. Thermal management of electronic products relies on the effec-tive dissipation of heat. This can be achieved by the optimization of the system design with the help of simulation methods. The precision of these models relies also on the used material data. For the deter

Alain Barbu, Emmanuel Clouet

The aim of this paper is to give a short review on cluster dynamics modeling in the field of atoms and point defects clustering in materials. It is shown that this method, due to its low computer cost, can handle long term evolution that cannot, in many cases, be obtained by Lattice Kinetic Monte Carlo methods. Indeed, such a possibility is achieved thanks t

T. Baba, K. Ishikawa, T. Yagi, N. Taketoshi

Thermoreflectance methods by picosecond pulse heating and by nanosecond pulse heating have been developed under the same geometrical configuration as the laser flash method by the National Metrology Institute of JAPAN, AIST. Using these light pulse heating methods, thermal diffusivity of each layer of multilayered thin films and boundary thermal resistance b

F. Amiranoff, D. Bernard, B. Cros, F. Jacquet

We present a summary of the beatwave particle acceleration program developed at Ecole Polytechnique. In dedicated experiments, plasma formation, plasma wave generation and saturation, and particle acceleration were successively studied and understood in detail. A maximum energy gain of 1.3 MeV was obtained, which is compatible with an accelerating gradient o

Z. Radivojevic, K. Andersson, K. Hashizume, M. Heino

Manufacturing electronic devices by printing techniques with low temperature sintering of nano-size material particles can revolutionize the electronics industry in coming years. The impact of this change to the industry can be significant enabling low-cost products and flexibility in manufacturing. implementation of a new production technology with new mate

A. Humphrey, F. Iwamuro, M. Villar-Martin, L. Binette

We present an investigation into the spatial variation of the rest-frame UV and optical line and continuum emission along the radio axis of the z=2.6 radio galaxy 0828+193, using long-slit spectra from the Keck II and Subaru telescopes. Line brightnesses, line ratios and electron temperatures are examined, and their relationship with the arm-length asymmetry

F. Schreuder, J. -G. Bij De Vaate

In the Square Kilometre Array (SKA) telescope [1], [2], the noise temperature of the first LNA must be reduced in order to reduce the necessary active area and the total system costs. Cooling the LNA locally would significantly decrease the noise figure but also the necessary power since not the whole system has to be cooled. For optimal thermal isolation, a

Marika Taylor

Recently exact agreement has been found between three-point correlators of chiral operators computed in string theory on AdS_3 x S^3 x T^4 with NS-NS flux and those computed in the symmetric orbifold CFT. However, it has also been shown that these correlators disagree with those computed in supergravity, under any identification of single particle operators

Xiang Ma, Peng Wang

Spacelike Willmore surfaces in 4-dimensional Lorentzian space forms, a topic in Lorentzian conformal geometry which parallels the theory of Willmore surfaces in $S^4$, are studied in this paper. We define two kinds of transforms for such a surface, which produce the so-called left/right polar surfaces and the adjoint surfaces. These new surfaces are again co

V. Szekely, G. Mezosi

Some years ago we have proposed a thermal mount with electronically variable thermal resistance [1]. In this earlier work the feasibility of such a structure has been demonstrated. Now we intend to realize this mount in a maturated form, suitable to the everyday use in the practice of package thermal qualification and modeling. The design of such a device ra

P. -O. Chapuis, S. Kumar Saha, S. Volz

A way to increase the Scanning Thermal Microscope (SThM) sensitivity in the harmonic 3w mode is to heat the probe with an AC current sufficiently high to generate a coupling between the AC and the DC signals. We detail in this paper how to properly take into account this coupling with a Wollaston-probe SThM. We also show how to link correctly the thermal con

M. Marcu, M. Vladutiu, H. Moldovan, M. Popa

Power consumption and heat dissipation become key elements in the field of high-end integrated circuits, especially those used in mobile and high-speed applications, due to their increase of transistor count and clock frequencies. Dynamic thermal management strategies have been proposed and implemented in order to mitigate heat dissipation. However, there is

V. V. Zhuravlev, N. I. Shakura

The instability of non-homoentropic axisymmetric flow of perfect fluid with respect to non-axisymmetric infinitesimal perturbations was investigated by numerical integration of hydrodynamical differential equations in two-dimensional approximation. The non-trivial influence of entropy gradient on unstable sound and surface gravity waves was revealed. In part

F. Stefani, P. -E. Bagnoli

This communication deals with a theoretical study of the hot spot onset (HSO) in cellular bipolar power transistors. This well-known phenomenon consists of a current crowding within few cells occurring for high power conditions, which significantly decreases the forward safe operating area (FSOA) of the device. The study was performed on a virtual sample by

W. Habra, P. Tounsi, J. -M. Dorkel

This paper presents an improved methodology to generate Compact Thermal Models "CTMs" by using (VHDL-AMS) modeling language. This methodology makes it possible to have Boundary Conditions Independent "BCI" CTMs for multi chip components and systems while taking into account the nonlinear thermal conductivity of semiconductors and other materi

G. Pupillo, A. Griessner, A. Micheli, M. Ortner

We study the realization of lattice models, where cold atoms and molecules move as extra particles in a dipolar crystal of trapped polar molecules. The crystal is a self-assembled floating mesoscopic lattice structure with quantum dynamics given by phonons. We show that within an experimentally accessible parameter regime extended Hubbard models with tunable

Tiina Suomijarvi

The Surface Detector of the Pierre Auger Observatory will consist of 1600 water Cherenkov tanks sampling ground particles of air showers produced by energetic cosmic rays. The arrival times are obtained from GPS and power is provided by solar panels. The construction of the array is nearly completed and a large number of detectors has been operational for mo

G. Buonaiuto, A. Irace, G. Breglio, P. Spirito

In this paper we report on a novel simulation tool designed for the 3D coupled electro-thermal simulation of Smart Power Mosfets, that is a tool capable of taking into account not only the electrical (and thermal) behaviour of the power device but also the different driving strategies as they are imposed by a control logic circuit which usually resides on th

G. Bognár, V. Szekely, M. Rencz

In this paper the methodology and the results of a quasi real-time thermal characterization tool and method for the temperature mapping of circuits and boards based on sensing the infrared radiation will be introduced. With the proposed method the IR radiation-distribution of boards from the close proximity of the sensor card is monitored in quasi real-time.

D. Pierscinska, K. Pierscinski, M. Bugajski, J. W. Tomm

In this work we present results of the analysis of thermal properties of high-power laser bars obtained by spatially resolved thermoreflectance (TR) spectroscopy. Thermoreflectance is a modulation technique relying on periodic facet temperature modulation induced by pulsed current supply of the laser. The periodic temperature change of the laser induces vari

J. Banaszczyk, G. De Mey, M. Janicki, A. Napieralski

This paper presents dynamic thermal analyses of a power amplifier. All the investigations are based on the transient junction temperature measurements performed during the circuit cooling process. The presented results include the cooling curves, the structure functions, the thermal time constant distribution and the Nyquist plot of the thermal impedance. Th

K. Fukutani, R. Singh, A. Shakouri

A network identification by deconvolution (NID) method is applied to the thermal transient response of packaged and unpackaged microcoolers. A thin film resistor on top of the device is used as the heat source and the temperature sensor. The package and the bonding thermal resistances can be easily identified by comparing structure functions. High-speed copl

A. Poppe, G. Farkas, G. Horvath

Besides their electrical properties the optical parameters of LEDs also depend on junction temperature. For this reason thermal characterization and thermal management play important role in case of power LEDs, necessitating both physical measurements and simulation tools. The focus of this paper is a combined electrical, thermal and optical characterization

A. Poppe, Y. Zhang, J. Wilson, G. Farkas

Thermal measurement and modeling of multi-die packages became a hot topic recently in different fields like RAM chip packaging or LEDs / LED assemblies, resulting in vertical (stacked) and lateral arrangement. In our present study we show results for a mixed arrangement: an opto-coupler device has been investigated with 4 chips in lateral as well as vertical

N. Vchare, M. Pecht

Prognostics is a process of assessing the extent of deviation or degradation of a product from its expected normal operating condition, and then, based on continuous monitoring, predicting the future reliability of the product. By being able to determine when a product will fail, procedures can be developed to provide advanced warning of failures, optimize m

V. Pankovic, M. Predojevic, P. Grujic

We propose a simple procedure for evaluating the main thermodynamical attributes of a Schwarzschild's black hole: Bekenstein-Hawking entropy, Hawking's temperature and Bekenstein's quantization of the surface area. We make use of the condition that the circumference of a great circle on the black hole horizon contains finite number of the corresp

J. Jiménez-Vicente, A. Castillo-Morales, E. Mediavilla, E. Battaner

We report the discovery of a galactic wind in the central region of the galaxy M100. This result is based on a careful 2D spectroscopic study performed on observations made with the fibre system INTEGRAL on the WHT. The primary evidence of the wind is the presence of blueshifted interstellar NaD absorption lines. The velocity field of the absorbers show a cl

Alejandra Valencia, Alessandro Cerè, Xiaojuan Shi, Gabriel Molina-Terriza

We demonstrate experimentally the tunable control of the joint spectrum, i.e. waveform and degree of frequency correlations, of paired photons generated in spontaneous parametric downconversion. This control is mediated by the spatial shape of the pump beam in a type-I noncollinear configuration. We discuss the applicability of this technique to other source

Dirk Schuricht, Fabian H. L. Essler

We determine dynamical response functions $<{\cal O}^\dagger(t,x_1){\cal O}(0,x_2)>$ in the scaling limit of the quantum Ising chain on the half line in the presence of a boundary magnetic field. Using a spectral representation in terms of infinite volume form factors and a boundary state, we derive an expansion for the correlator that is found to be rapidly

M. Teshima, B. Dolgoshein, R. Mirzoyan, J. Nincovic

The SiPM is a novel solid state photodetector which can be operated in the single photon counting mode. It has excellent features, such as high quantum efficiency, good charge resolution, fast response, very compact size, high gain of 106, very low power consumption, immunity to the magnetic field and low bias voltage (30-70V). Drawbacks of this device curre

Andreas Peters

This is a short presentation of the results for the pion-nucleon distribution amplitudes which are expressed in terms of the nucleon distribution amplitudes with the help of current algebra. Everything is considered to be at threshold.

Takashi Sekii, Alexander G. Kosovichev, Junwei Zhao, Saku Tsuneta

Results from initial helioseismic observations by Solar Optical Telescope onboard Hinode are reported. It has been demonstrated that intensity oscillation data from Broadband Filter Imager can be used for various helioseismic analyses. The k-omega power spectra, as well as corresponding time-distance cross-correlation function that promises high-resolution t

Fabio Fontanot, Pierluigi Monaco, Laura Silva, Andrea Grazian

In order to gain insight into the physical mechanisms leading to the formation of stars and their assembly in galaxies, we compare the predictions of the MOdel for the Rise of GAlaxies aNd Active nuclei (MORGANA) to the properties of K- and 850 micron-selected galaxies (such as number counts, redshift distributions and luminosity functions) by combining MORG

Hiroshi Imai

Highly collimated jets found in AGB and post-AGB stars are expected to play an important role for shaping planetary nebulae. Recent VLBI observations of H2O maser sources have revealed that some of the spatio-kinematical structures of H2O maser sources exhibit stellar jets with extremely spatially and kinematically high collimation. Such stellar H2O maser je

Georgi Pavlovski, Christian R. Kaiser, Edward C. D. Pope

We present a phenomenological model of the dynamics of buoyant bubbles in the atmosphere of a cluster of galaxies. The derived equations describe velocity, size, mass, temperature and density of the buoyant bubbles as functions of time based on several simple approximations. The constructed model is then used to interpret results of a numerical experiment of

Hidetomo Sawai, Kei Kotake, Shoichi Yamada

A series of numerical simulations on magnetorotational core-collapse supernovae are carried out. Dipole-like configurations which are offset northward are assumed for the initially strong magnetic fields together with rapid differential rotations. Aims of our study are to investigate effects of the offset magnetic field on magnetar kicks and on supernova dyn

Raphael M. Jungers, Vladimir Y. Protasov, Vincent D. Blondel

Overlap-free words are words over the binary alphabet $A=\{a, b\}$ that do not contain factors of the form $xvxvx$, where $x \in A$ and $v \in A^*$. We analyze the asymptotic growth of the number $u_n$ of overlap-free words of length $n$ as $ n \to \infty$. We obtain explicit formulas for the minimal and maximal rates of growth of $u_n$ in terms of spectral

Eugenio Lippiello, Lucilla de Arcangelis, Cataldo Godano

A crucial point in the debate on feasibility of earthquake prediction is the dependence of an earthquake magnitude from past seismicity. Indeed, whilst clustering in time and space is widely accepted, much more questionable is the existence of magnitude correlations. The standard approach generally assumes that magnitudes are independent and therefore in pri

Sung Seok A. Seo, Jun Hee Lee, Ho Nyung Lee, Matthew F. Chisholm

We report on the growth and properties of high quality bicolor oxide superlattices, composed of two perovskites out of BaTiO3, CaTiO3, and SrTiO3. The artificially grown superlattices are structurally unique and have a macroscopically homogeneous phase, which is not feasible to recreate in bulk form. By artificial structuring, it is found that the polarizati

Erik Koelink, Walter Van Assche

We study a q-logarithm which was introduced by Euler and give some of its properties. This q-logarithm did not get much attention in the recent literature. We derive basic properties, some of which were already given by Euler in a 1751-paper and 1734-letter to Daniel Bernoulli. The corresponding q-analogue of the dilogarithm is introduced. The relation to th

Svante Janson, Andrew Thomason

We consider the number of vertices that must be removed from a graph G in order that the remaining subgraph has no component with more than k vertices. Our principal observation is that, if G is a sparse random graph or a random regular graph on n vertices with n tending to infinity, then the number in question is essentially the same for all values of k suc

Fuminobu Takahashi

We have recently shown that, if the inflaton has a nonzero vacuum expectation value, it generically couples to any matter fields that appear in the superpotential at the tree level, and to any gauge sectors through anomalies in the supergravity. Through these processes, the inflaton decays into the supersymmetry breaking sector, producing many gravitinos. Th

M. Perucho, J. M. Marti

The evolution of FRI jets has been long studied in the framework of the FRI-FRII dichotomy. In this paper, we test the present theoretical and observational models via a relativistic numerical simulation of the jets in the radio galaxy 3C 31. We use the parameters derived from the modelling presented by \cite{lb02a,lb02b} as input parameters for the simulati

Masahiro Hoshino

A particle acceleration mechanism by radiation pressure of precursor waves in a relativistic shock is studied. For a relativistic, perpendicular shock with the upstream bulk Lorentz factor of $γ_1 \gg 1$, large amplitude electromagnetic (light) waves are known to be excited in the shock front due to the synchrotron maser instability, and those waves can prop

V. Nosenko, S. Zhdanov, G. Morfill

Experimental results on the dislocation dynamics in a two-dimensional plasma crystal are presented. Edge dislocations were created in pairs in lattice locations where the internal shear stress exceeded a threshold and then moved apart in the glide plane at a speed higher than the sound speed of shear waves, $C_T$. The experimental system, a plasma crystal, a

Alexander A. Ershov

Simultaneous dual-frequency observations of giant pulses from the Crab pulsar were performed at the frequencies of 61 and 111 MHz. It is shown that scattering of giant pulses from the Crab pulsar occurs at thick, and not at thin screen.

Sixia Yu, Qing Chen, C. H. Oh

We introduce a purely graph-theoretical object, namely the coding clique, to construct quantum errorcorrecting codes. Almost all quantum codes constructed so far are stabilizer (additive) codes and the construction of nonadditive codes, which are potentially more efficient, is not as well understood as that of stabilizer codes. Our graphical approach provide

E. Cizmar, M. Ozerov, O. Ignatchik, T. P. Papageorgiou

Results of magnetization and high-field ESR studies of the new spin-1 Haldane-chain material [Ni(C2H8N2)2NO2](BF4) (NENB) are reported. A definite signature of the Haldane state in NENB was obtained. From the analysis of the frequency-field dependence of magnetic excitations in NENB, the spin-Hamiltonian parameters were calculated, yielding Delta = 17.4 K, g

Nguyen Tu Cuong, Tran Tuan Nam

We introduce a local homology theory for linearly compact modules which is in some sense dual to the local cohomology theory of A. Grothendieck. Some basic properties such as the noetherianness, the vanishing and non-vanishing of local homology modules of linearly compact modules are proved. A duality theory between local homology and local cohomology module

P. K. Grimes, O. G. King, G. Yassin, M. E. Jones

We present the design and test results of a compact C-band orthomode transducer which comprises four rectangular probes orthogonally arranged in a circular waveguide, designed to work in the WG13 band. Measurements of the system in the frequency range 4.64 GHz to 7.05 GHz agree very well with simulation results and show a cross-polarisation level below -58 d

Heng Lian

Super-resolution is an important but difficult problem in image/video processing. If a video sequence or some training set other than the given low-resolution image is available, this kind of extra information can greatly aid in the reconstruction of the high-resolution image. The problem is substantially more difficult with only a single low-resolution imag

Jan Wiersig, Martina Hentschel

A drawback of high-quality modes in optical microdisks is their isotropic light emission characteristics. Here we report a novel, robust, and general mechanism that results in highly directional light emission from those modes. This surprising finding is explained by a combination of wave phenomena (wave localization along unstable periodic ray trajectories)

S. Moch, C. Schneider

We report on the calculation of multi-loop Feynman integrals for single-scale problems by means of difference equations in Mellin space. The solution to these difference equations in terms of harmonic sums can be constructed algorithmically over difference fields, the so-called Pi-Sigma-fields. We test the implementaion of the Mathematica package Sigma on ex

Imed Basdouri, Mabrouk Ben Ammar

We compute the first cohomology spaces $H^1(\mathfrak{osp}(1|2);\mathfrak{D}_{λ,μ})$ ($λ, μ\in\mathbb{R}$) of the Lie superalgebra $\mathfrak{osp}(1|2)$ with coefficients in the superspace $\mathfrak{D}_{λ,μ}$ of linear differential operators acting on weighted densities on the supercircle $S^{1|1}$. The structure of these spaces was conjectured in \cite{gmo

Kentaro Nagao

We have two constructions of the level-$(0,1)$ irreducible representation of the quantum toroidal algebra of type $A$. One is due to Nakajima and Varagnolo-Vasserot. They constructed the representation on the direct sum of the equivariant K-groups of the quiver varieties of type $\hat{A}$. The other is due to Saito-Takemura-Uglov and Varagnolo-Vasserot. They

M. Shibata, Y. Sekiguchi, R. Takahashi

We present our first numerical results of axisymmetric magnetohydrodynamic simulations for neutrino-cooled accretion tori around rotating black holes in general relativity. We consider tori of mass $\sim 0.1$--0.4$M_{\odot}$ around a black hole of mass $M=4M_{\odot}$ and spin $a=0$--$0.9M$; such systems are candidates for the central engines of gamma-ray bur

N. D. Hari Dass, Peter Matlock

A covariant calculus for the construction of effective string theories is developed. Effective string theory, describing quantum string-like excitations in arbitrary dimension, has in the past been constructed using the principles of conformal field theory, but not in a systematic way. Using the freedom of choice of field definition, a particular field defin

V. S. Zapasskii, G. G. Kozlov

It is shown that the effect of hole-burning under conditions of coherent population oscillations as well as the light pulse delay in a saturable absorber (a modification of the &#34;slow light&#34; effect) can be interpreted, in a comprehensive way, in terms of {\it intensity spectrum} of the light and {\it intensity-related susceptibility} of the non-linear

Xiao-Wu Chen

We introduce the notion of relative singularity category with respect to any self-orthogonal subcategory $ω$ of an abelian category. We introduce the Frobenius category of $ω$-Cohen-Macaulay objects, and under some reasonable conditions, we show that the stable category of $ω$-Cohen-Macaulay objects is triangle-equivalent to the relative singularity category

J. P. Willis, F. Courbin, J. P. Kneib, D. Minniti

We present the results of a continuing survey to detect Lya emitting galaxies at redshifts z~9: the ZEN (&#34;z equals nine&#39;&#39;) survey. We have obtained deep VLT/ISAAC observations in the narrow J-band filter NB119 directed towards three massive lensing clusters: Abell clusters 1689, 1835, and 114. The foreground clusters provide a magnified view of t

Sei-ichiro Watanabe, D. N. C. Lin

Protoplanetary disks are mainly heated by radiation from the central star. Since the incident stellar flux at any radius is sensitive to the disk structure near that location, an unstable feedback may be present. Previous investigations show that the disk would be stable to finite-amplitude temperature perturbations if the vertical height of optical surface