Random transverse-field Ising chain with long-range interactions

We study the low-energy properties of the long-range random transverse-field Ising chain with ferromagnetic interactions decaying as a power alpha of the distance. Using variants of the strong-disorder renormalization group method, the critical behavior is found to be controlled by a strong-disorder fixed point with a finite dynamical exponent z_c=alpha. Approaching the critical point, the correlation length diverges exponentially. In the critical point, the magnetization shows an alpha-independent logarithmic finite-size scaling and the entanglement entropy satisfies the area law. These observations are argued to hold for other systems with long-range interactions, even in higher dimensions.Comment: 6 pages, 4 figure

Rendezetlen rendszerek statisztikus fizikája = Statistical physics of disordered systems

A pályázat keretében nagy szabadsági fokú fizikai rendszerek kooperatív viselkedését vizsgáltuk rendezetlenség jelenlétében. A szingularitásokat (fázisátalakulások, Griffiths effektusok) kísérő jelenségeket tanulmányoztuk és egyensúlyi és egyensúlytól távoli folyamatokat is vizsgáltunk. A rendezetlen kvantum rendszerek esetén korábbi kutatásainkat folytatva az un. erős rendezetlenségi renormálási csoport alkalmazásával különböző egy- és kétdimenziós rendszerek fázisdiagramját és alacsony energiás gerjesztéseit vizsgáltuk. Emellett új eredményeket értünk el a kvantumállapotok összefonódását mérő Neumann-féle entrópia meghatározásánál is. Az egyensúlytól távoli rendszereknél részint az öregedés jelenségével foglalkoztunk a kritikus nemegyensúlyi relaxáció során, részint hajtott rácsgáz modelleket rendezetlenség jelenlétében vizsgáltunk. Végül, a rendezetlenség dominálta klasszikus rendszereknél fázisátalakulásokat és az azokat kísérő geometriai objektumok (klaszterek, fürtök) tulajdonságait vizsgáltuk. A projekt keretében elért eredményeket 29 idegennyelvű szakcikkben közöltük, melyek összesített impakt faktora több mint 90 és melyekre ezidáig több mint 130 független hivatkozás érkezett. A pályázat futamideje alatt egy sikeres PhD védés történt és további két PhD disszertáció védésre be van nyújtva. | Within the project the cooperative behavior of physical systems with large degree of freedom is studied in the presence of disorder. We have determined the properties of singularities (phase transitions, Griffiths effects) and studied both equilibrium and nonequilibrium processes. For disordered quantum systems we have continued our studies on the use of the strong disorder renormalization group method to obtain the phase diagram and low energy excitations of different one- and two-dimensional systems. We have also obtained new results about entanglement of quantum systems and the related von Neumann entropy. For nonequilibrium systems we have studied ageing during nonequilibrium critical relaxation, as well as driven lattice gas systems in the presence of disorder. Finally, in the third field of disorder dominated classical systems we have studied phase transitions and the related geometrical problems of clusters. Our results obtained during this project have been published in 29 papers in international journals and for these we have already obtained more than 130 citations. During the project 1 PhD dissertation has been succesfully defended and two others are submitted for defence

Entanglement between random and clean quantum spin chains

The entanglement entropy in clean, as well as in random quantum spin chains has a logarithmic size-dependence at the critical point. Here, we study the entanglement of composite systems that consist of a clean and a random part, both being critical. In the composite, antiferromagnetic XX-chain with a sharp interface, the entropy is found to grow in a double-logarithmic fashion ${\cal S}\sim \ln\ln(L)$, where $L$ is the length of the chain. We have also considered an extended defect at the interface, where the disorder penetrates into the homogeneous region in such a way that the strength of disorder decays with the distance $l$ from the contact point as $\sim l^{-\kappa}$. For $\kappa<1/2$, the entropy scales as ${\cal S}(\kappa) \simeq (1-2\kappa){\cal S}(\kappa=0)$, while for $\kappa \ge 1/2$, when the extended interface defect is an irrelevant perturbation, we recover the double-logarithmic scaling. These results are explained through strong-disorder RG arguments.Comment: 12 pages, 7 figures, Invited contribution to the Festschrift of John Cardy's 70th birthda

Génexpressziós profil vizsgálata a pajzsmirigy hámeredetű tumoraiban = Gene-expression profiles in the thyroid tumors of epithelial origin

A thyroid tumorok kialakulása az epitelialis carcinogenezis többlépcsős modelljeként irható le. Tumor szuppresszor gének, és az onkogének három fő csoportjába tartozó gének (GTP-kötő protein, sejtmagi transzkripciós faktor, tirozin kináz) mutációinak, expressziós mintázatának megváltozása szerepet játszik a tumor kialakulásában, progressziójában. Célkitűzéseink között szerepelt az irodalomban közölt génexpressziós mintázatok magyarországi populáción való vizsgálata, valamint egyéni rizikóbecslés alátámasztása érdekében egyes gének genetikai polimorfizmusának vizsgálata pajzsmirigy tumoros betegek mintáiból. RNS micro array segítségével meghatározzuk különböző, de főként hámeredetű pajzsmirigy tumorok jellemző génexpressziós profilját, mely megalapozza egy, un: "thyroid chip" megszerkesztését, létrehozását. Eredményeink azt mutatják, hogy meghatározható egy jellegzetes - 90-100 génből álló -génexpressziós profil pajzsmirigy tumorok esetén, de kutatási eredményeink még kvantitatív RT-PCR-os alátámasztásra szorulnak (jelenleg folyó kísérlet), valamint nagyobb mintaszámon vissza kell ellenőrizni hipotézisünket. | Thyroid tumors can be considered as a multi-step model of epithelial carcinogenesis. Tumor-suppressor genes and three classes of oncogenes - coding GPT-binding proteins, nuclear transcription factors and tyrosine kinases - play roles in its development and progression. We aimed to study the pattern of gene expressions in the Hungarian population according to the data in specialized literature, and also analyzing the polymorphism of certain genes from samples of patient with thyroid cancer in the interest of personal risk assessment. We determine the various, but mainly epithelial thyroid tumors' specific profile of gene expression by applying RNA micro array. This might establish the accomplishment of the "thyroid chip". Our results show, that a specific profile of gene expression - consisting of 90-100 genes - is could be determined concerning thyroid tumors, but these results should be supported by using quantitative RT-PCR method (this experiment is currently runs in our institute) in addition our hypothesis is needed to be controlled in wider population

Calculations of Performance Losses for Automobile Vehicles

Vehicle-energetic-models are used to analyze the performances and when a comprehensive structure is established even optimization could be done. For these kinds of models, the losses of the vehicles have to be known. These losses could significantly effect of the vehicle fuel consumption. From these losses the rolling resistance, drive elements and aerodynamic drag are discussed. This paper reviews some of the literatures that describes the calculation methods and gives us some idea about the degree of their value. Our further goals are to have an UpToDate loss coefficient dataset and calculation methods for further vehicle-energetic modelling

Effects of yeast trehalose-6-phosphate synthase 1 on gene expression and carbohydrate contents of potato leaves under drought stress conditions

BACKGROUND: The development of drought-tolerant, elite varieties of potato (Solanum tuberosum L.) is a challenging task, which might be achieved by introducing transgenic lines into breeding. We previously demonstrated that strains of the White Lady potato cultivar that express the yeast trehalose-6-phosphate synthase ( TPS1) gene exhibit improved drought tolerance. RESULTS: We investigated the responses of the drought-sensitive potato cultivar White Lady and the drought-tolerant TPS1 transgenic variant to prolonged drought stress at both the transcriptional and metabolic levels. Leaf mRNA expression profiles were compared using the POCI microarray, which contains 42,034 potato unigene probes. We identified 379 genes of known function that showed at least a 2-fold change in expression across genotypes, stress levels or the interaction between these factors. Wild-type leaves had twice as many genes with altered expression in response to stress than TPS1 transgenic leaves, but 112 genes were differentially expressed in both strains. We identified 42 transcription factor genes with altered expression, of which four were uniquely up-regulated in TPS1 transgenic leaves. The majority of the genes with altered expression that have been implicated in photosynthesis and carbohydrate metabolism were down-regulated in both the wild-type and TPS1 transgenic plants. In agreement with this finding, the starch concentration of the stressed leaves was very low. At the metabolic level, the contents of fructose, galactose and glucose were increased and decreased in the wild-type and TPS1 transgenic leaves, respectively, while the amounts of proline, inositol and raffinose were highly increased in both the wild-type and TPS1 transgenic leaves under drought conditions. CONCLUSIONS: To our knowledge, this study is the most extensive transcriptional and metabolic analysis of a transgenic, drought-tolerant potato line. We identified four genes that were previously reported as drought-responsive in non-transgenic Andean potato cultivars. The substantial increases in proline, inositol and raffinose contents detected in both the wild-type and TPS1 transgenic leaves appears to be a general response of potatoes to drought stress. The four transcription factors uniquely up-regulated in TPS1 transgenic leaves are good candidates for future functional analyses aimed at understanding the regulation of the 57 genes with differential expression in TPS1 transgenic leaves