Charge Kondo anomalies in PbTe doped with Tl impurities

We investigate the properties of PbTe doped with a small concentration $x$ of Tl impurities acting as acceptors and described by Anderson impurities with negative onsite correlation energy. We use the numerical renormalization group method to show that the resulting charge Kondo effect naturally accounts for the unusual low temperature and doping dependence of normal state properties, including the self-compensation effect in the carrier density and the non-magnetic Kondo anomaly in the resistivity. These are found to be in good qualitative agreement with experiment. Our results for the Tl s-electron spectral function provide a new interpretation of point contact data.Comment: 5 pages, 3 figures; published versio

Seismic Retrofitting Using Micropile Systems Centrifugal Model Studies

A series of centrifuge tests were conducted on micropile group and network systems in order to investigate the response to earthquake loading and soil-micropile interaction behavior. Model tests on group and network systems embedded in loose to medium dry sand are described. Micropile bending moment, deflection, and acceleration were measured during testing. Dynamic p-y curves were derived from the measurements for low and high levels of shaking and were compared with the backbone p-y curves for sand recommended by API and other published data. Group and network effects were investigated for different configurations and at different levels of loading. For the selected frequency of excitation, the results indicate a positive group effect increasing with the number of piles and the batter angle. This paper describes the experimental procedures used to carry out the centrifugal model tests and summarizes the main preliminary results

Accurate screened exchange band structures for transition metal monoxides MnO, FeO, CoO and NiO

We report calculations of the band structures and density of states of the four transition metal monoxides MnO, FeO, CoO and NiO using the hybrid density functional sX-LDA. Late transition metal oxides are prototypical examples of strongly correlated materials, which pose challenges for electronic structure methods. We compare our results with available experimental data and show that our calculations yield accurate predictions for the fundamental band gaps and valence bands of FeO, CoO and NiO. For MnO, the band gaps are underestimated, suggesting additional many-body effects that are not captured by our screened hybrid functional approach.Comment: 9 pages, 3 figures, 3 table

Molecular and biological characterization of low-pathogenic H9N2 influenza viruses isolated in Israel

All Israeli H9N2-strain viruses used in the present study were subdivided among three groups: groups A and B viruses contained – in all eight segments – 90658/00-like and 1304/03-like sequences, respectively; Group C comprised viruses isolated in 2006-2010, which contained four 1304/03-like segments and four 1525/06-like segments. Molecular analysis revealed that most of the isolates had an RSSR motif at the cleavage site of haemagglutinin. Most of the viruses had an haemagglutinin with L216 typical of humans, and internal proteins associated with the avian host specificity. The studied viruses infected the majority of the directly inoculated birds. Exposure to the virus with full8length PB1-F2 protein for 24 h caused destruction of mitochondria and cell death in cultures of human macrophages, and this effect was not associated with activation of protein p53. A virus with truncated PB1-F2 protein exhibited no destructive effect on mitochondria, but induced enhanced production of pro-apoptotic P53 proteinВсі ізраїльські віруси штаму H9N2, що використовуються в цьому дослідженні, були розділені на групи: віруси груп А і В містили відповідно - у всіх восьми сегментах - 90658/00-подібні і 1304/03-подібні послідовності; група C складалася з вірусів, виділених у 2006-2010 роках, які містили чотири 1304/03-подібних сегмента і чотири 1525/06-подібних сегмента. Молекулярний аналіз показав, що більшість штамів мали RSSR-мотив в сайті розщеплення гемаглютиніну. Більшість вірусів містили гемаглютинін з типовим для людей L216, і, крім того, внутрішні білки, характерні для птахів. Вивчені віруси заразили більшість щеплених птахів безпосередньо. Вплив вірусу з повнорозмірною PB1-F2 білка протягом 24 год викликав руйнування мітохондрій і загибель клітин в культурах людських макрофагів, і цей ефект не був пов’язаний з активацією білка р53. Вірус з усіченою ланцюгом білка PB1-F2 не чинив руйнівного впливу на мітохондрії, але індукував підвищений сінтез проапоптотического білка Р53.Всі ізраїльські віруси штаму H9N2, що використовуються в цьому дослідженні, були розділені на групи: віруси груп А і В містили відповідно - у всіх восьми сегментах - 90658/00-подібні і 1304/03-подібні послідовності; група C складалася з вірусів, виділених у 2006-2010 роках, які містили чотири 1304/03-подібних сегмента і чотири 1525/06-подібних сегмента. Молекулярний аналіз показав, що більшість штамів мали RSSR-мотив в сайті розщеплення гемаглютиніну. Більшість вірусів містили гемаглютинін з типовим для людей L216, і, крім того, внутрішні білки, характерні для птахів. Вивчені віруси заразили більшість щеплених птахів безпосередньо. Вплив вірусу з повнорозмірною PB1-F2 білка протягом 24 год викликав руйнування мітохондрій і загибель клітин в культурах людських макрофагів, і цей ефект не був пов’язаний з активацією білка р53. Вірус з усіченою ланцюгом білка PB1-F2 не чинив руйнівного впливу на мітохондрії, але індукував підвищений сінтез проапоптотического білка Р53

Enhanced superconducting pairing interaction in indium-doped tin telluride

The ferroelectric degenerate semiconductor Sn$_{1-\delta}$Te exhibits superconductivity with critical temperatures, $T_c$, of up to 0.3 K for hole densities of order 10$^{21}$ cm$^{-3}$. When doped on the tin site with greater than $x_c$ $= 1.7(3)$ indium atoms, however, superconductivity is observed up to 2 K, though the carrier density does not change significantly. We present specific heat data showing that a stronger pairing interaction is present for $x > x_c$ than for $x < x_c$. By examining the effect of In dopant atoms on both $T_c$ and the temperature of the ferroelectric structural phase transition, $T_{SPT}$, we show that phonon modes related to this transition are not responsible for this $T_c$ enhancement, and discuss a plausible candidate based on the unique properties of the indium impurities.Comment: 7 page

Lattice Dynamics and Specific Heat of α\alpha - GeTe: a theoretical and experimental study

We extend recent \textit{ab initio} calculations of the electronic band structure and the phonon dispersion relations of rhombohedral GeTe to calculations of the density of phonon states and the temperature dependent specific heat. The results are compared with measurements of the specific heat. It is discovered that the specific heat depends on hole concentration, not only in the very low temperature region (Sommerfeld term) but also at the maximum of $C_p/T^3$ (around 16 K). To explain this phenomenon, we have performed \textit{ab initio} lattice dynamical calculations for GeTe rendered metallic through the presence of a heavy hole concentration ($p$ $\sim$ 2$\times$ 10$^{21}$ cm$^{-3}$). They account for the increase observed in the maximum of $C_p/T^3$.Comment: 8 pages, 7 figures, ref. 19 correcte

Self-stabilizing algorithms for Connected Vertex Cover and Clique decomposition problems

In many wireless networks, there is no fixed physical backbone nor centralized network management. The nodes of such a network have to self-organize in order to maintain a virtual backbone used to route messages. Moreover, any node of the network can be a priori at the origin of a malicious attack. Thus, in one hand the backbone must be fault-tolerant and in other hand it can be useful to monitor all network communications to identify an attack as soon as possible. We are interested in the minimum \emph{Connected Vertex Cover} problem, a generalization of the classical minimum Vertex Cover problem, which allows to obtain a connected backbone. Recently, Delbot et al.~\cite{DelbotLP13} proposed a new centralized algorithm with a constant approximation ratio of $2$ for this problem. In this paper, we propose a distributed and self-stabilizing version of their algorithm with the same approximation guarantee. To the best knowledge of the authors, it is the first distributed and fault-tolerant algorithm for this problem. The approach followed to solve the considered problem is based on the construction of a connected minimal clique partition. Therefore, we also design the first distributed self-stabilizing algorithm for this problem, which is of independent interest

Human Gene and Protein Database (HGPD): a novel database presenting a large quantity of experiment-based results in human proteomics

Completion of human genome sequencing has greatly accelerated functional genomic research. Full-length cDNA clones are essential experimental tools for functional analysis of human genes. In one of the projects of the New Energy and Industrial Technology Development Organization (NEDO) in Japan, the full-length human cDNA sequencing project (FLJ project), nucleotide sequences of approximately 30 000 human cDNA clones have been analyzed. The Gateway system is a versatile framework to construct a variety of expression clones for various experiments. We have constructed 33 275 human Gateway entry clones from full-length cDNAs, representing to our knowledge the largest collection in the world. Utilizing these clones with a highly efficient cell-free protein synthesis system based on wheat germ extract, we have systematically and comprehensively produced and analyzed human proteins in vitro. Sequence information for both amino acids and nucleotides of open reading frames of cDNAs cloned into Gateway entry clones and in vitro expression data using those clones can be retrieved from the Human Gene and Protein Database (HGPD, http://www.HGPD.jp). HGPD is a unique database that stores the information of a set of human Gateway entry clones and protein expression data and helps the user to search the Gateway entry clones

Experimental study of negative photoconductivity in n-PbTe(Ga) epitaxial films

We report on low-temperature photoconductivity (PC) in n-PbTe(Ga) epitaxial films prepared by the hot-wall technique on -BaF_2 substrates. Variation of the substrate temperature allowed us to change the resistivity of the films from 10^8 down to 10_{-2} Ohm x cm at 4.2 K. The resistivity reduction is associated with a slight excess of Ga concentration, disturbing the Fermi level pinning within the energy gap of n-PbTe(Ga). PC has been measured under continuous and pulse illumination in the temperature range 4.2-300 K. For films of low resistivity, the photoresponse is composed of negative and positive parts. Recombination processes for both effects are characterized by nonexponential kinetics depending on the illumination pulse duration and intensity. Analysis of the PC transient proves that the negative photoconductivity cannot be explained in terms of nonequilibrium charge carriers spatial separation of due to band modulation. Experimental results are interpreted assuming the mixed valence of Ga in lead telluride and the formation of centers with a negative correlation energy. Specifics of the PC process is determined by the energy levels attributed to donor Ga III, acceptor Ga I, and neutral Ga II states with respect to the crystal surrounding. The energy level corresponding to the metastable state Ga II is supposed to occur above the conduction band bottom, providing fast recombination rates for the negative PC. The superposition of negative and positive PC is considered to be dependent on the ratio of the densities of states corresponding to the donor and acceptor impurity centers.Comment: 7 pages, 4 figure

ТЕРМОЭЛЕКТРИЧЕСКИЕ СВОЙСТВА МАТЕРИАЛА НА ОСНОВЕ (Bi,Sb)2Te3, ПОЛУЧЕННОГО МЕТОДОМ ИСКРОВОГО ПЛАЗМЕННОГО СПЕКАНИЯ

Thermoelectric properties of (Bi,Sb)2Te3 nanostructured bulk material as a function of composition and spark plasma sintering temperature were investigated. The Bi0,4Sb1,6Te3 alloys at sintering temperature 450—500 °C with ZT=1,25—1,28 figure of merit was fabricated. Thermoelectric properties ad a function ofsintering temperature above 400 °C correlate with fine structure change. It was found that point structure defects introduce essential contribution to the formation of nanostructured material thermoelectric properties.Исследована зависимость термоэлектрических свойств наноструктурированного объемногоматериала (Bi,Sb)2Te3 от состава и температуры SPS−спекания ТSPS. Обнаружено, что твердыйраствор Bi0,4Sb1,6Te3, спеченный при температуре 450—500 °С, имеет термоэлектрическуюэффективность ZT = 1,25÷1,28. Зависимость термоэлектрических свойств от температурыспекания ТSPS выше 400 °С коррелирует с изменением тонкой структуры материала, котороеопределяется перераспределением донорных точечныхдефектов вакансионного типа впроцессе повторной рекристаллизации. Установлено, что точечные структурные дефекты вносятсущественный вклад в формирование термоэлектрическихсвойств наноструктурированногоматериала