Diffraction dissociation in proton-proton collisions at s\sqrt{s} = 0.9 TeV, 2.76 TeV and 7 TeV with ALICE at the LHC

The relative rates of single- and double- diffractive processes were measured with the ALICE detector by studying properties of gaps in the pseudorapidity distribution of particles produced in proton-proton collisions at $\sqrt{s}$ = 0.9 TeV, 2.76 TeV and 7 TeV. ALICE triggering efficiencies are determined for various classes of events, using a detector simulation validated with data on inclusive particle production. Cross-sections are determined using van der Meer scans to measure beam properties and obtain a measurement of the luminosity

Surface Electronic Structures and Field Emission Currents at Sodium Overlayers on Low-Index Tungsten Surfaces

The total energy distributions (TEDs) of the emission currents in field emission and surface photofield emission and the overlayer-induced modifications in the surface electronic structures from the technologically important W surfaces with the commensurate W(100)/Na c(2x2), W(110)/Na (2x2) and W(111)/Na (1x1) overlayers are calculated. The TEDs obtained by our recent numerical method that extends the full-potential linear augmented plane wave method for the electronic structures to the study of field and photofield emission are used to interpret the shifts of the peaks in the experimental TEDs in field emission and photofield emission from the W(100) and W(110) surfaces at sub-monolayer and monolayer Na coverage. Hybridization of the 3s Na states with the pairs of dz2-like surface states of the strong Swanson hump in clean W(100) and surface resonances in clean W(111) below the Fermi energy shifts these W states by about -1.2 eV and -1.0 eV, thus stabilizing these states, to yield new strong peaks in the TEDs in field emission and photofield emission from W(100)/Na c(2x2) and W(111)/Na (1x1) respectively. The effect of Na intralayer interactions are discussed and are shown to shift the strong s- and p-like peaks in the surface density of states of W(110) below and above the Fermi energy respectively to lower energy with increased Na coverage, in agreement with experiments.Comment: 12 page

Counting Berg partitions

We call a Markov partition of a two dimensional hyperbolic toral automorphism a Berg partition if it contains just two rectangles. We describe all Berg partitions for a given hyperbolic toral automorphism. In particular there are exactly (k + n + l + m)/2 nonequivalent Berg partitions with the same connectivity matrix (k, l, m, n)

EVALUATION OF THE APRICOT GENE POOL IN THE SOUTHERN URALS

Anatomic, morphological and physiological characteristics of the genus Zinnia L. have been studied in the climatic environments of the foothill zone of the Crimea. Xeromorphic features have been identified in the anatomical structure of the stem and leaf in the species Zinnia рeruviana L., Z. violacea Cav., and Z. haageana Regel. Comparative analysis of the genus Zinnia L. has shown that its species differ in the degree of lignification of their tissues and the intensity of pubescence. As for water scarcity, the most drought-resistant species has been found: Z. violacea Cav. (4.6%)

Bayesian detection of unmodeled bursts of gravitational waves

The data analysis problem of coherently searching for unmodeled gravitational-wave bursts in the data generated by a global network of gravitational-wave observatories has been at the center of research for almost two decades. As data from these detectors is starting to be analyzed, a renewed interest in this problem has been sparked. A Bayesian approach to the problem of coherently searching for gravitational wave bursts with a network of ground-based interferometers is here presented. We demonstrate how to systematically incorporate prior information on the burst signal and its source into the analysis. This information may range from the very minimal, such as best-guess durations, bandwidths, or polarization content, to complete prior knowledge of the signal waveforms and the distribution of sources through spacetime. We show that this comprehensive Bayesian formulation contains several previously proposed detection statistics as special limiting cases, and demonstrate that it outperforms them.Comment: 18 pages, 3 figures, revisions based on referee comment

A review of simulation and modeling approaches in microbiology

Bacterial communities are tightly interconnected systems consisting of numerous species making it challenging to analyze their structure and relations. There are several experimental techniques providing heterogeneous data concerning various aspects of this object. A recent avalanche of metagenomic data challenges not only biostatisticians but also biomodelers, since these data are essential to improve the modeling quality while simulation methods are useful to understand the evolution of microbial communities and their function in the ecosystem. An outlook on the existing modeling and simulation approaches based on different types of experimental data in the field of microbial ecology and environmental microbiology is presented. A number of approaches focusing on a description of such microbial community aspects as its trophic structure, metabolic and population dynamics, genetic diversity as well as spatial heterogeneity and expansion dynamics is considered. We also propose a classification of the existing software designed for simulation of microbial communities. It is shown that although the trend for using multiscale/hybrid models prevails, the integration between models concerning different levels of biological organization of communities still remains a problem to be solved. The multiaspect nature of integration approaches used to model microbial communities is based on the need to take into account heterogeneous data obtained from various sources by applying high-throughput genome investigation methods

Magnetic Catalysis and Quantum Hall Ferromagnetism in Weakly Coupled Graphene

We study the realization in a model of graphene of the phenomenon whereby the tendency of gauge-field mediated interactions to break chiral symmetry spontaneously is greatly enhanced in an external magnetic field. We prove that, in the weak coupling limit, and where the electron-electron interaction satisfies certain mild conditions, the ground state of charge neutral graphene in an external magnetic field is a quantum Hall ferromagnet which spontaneously breaks the emergent U(4) symmetry to U(2)XU(2). We argue that, due to a residual CP symmetry, the quantum Hall ferromagnet order parameter is given exactly by the leading order in perturbation theory. On the other hand, the chiral condensate which is the order parameter for chiral symmetry breaking generically obtains contributions at all orders. We compute the leading correction to the chiral condensate. We argue that the ensuing fermion spectrum resembles that of massive fermions with a vanishing U(4)-valued chemical potential. We discuss the realization of parity and charge conjugation symmetries and argue that, in the context of our model, the charge neutral quantum Hall state in graphene is a bulk insulator, with vanishing longitudinal conductivity due to a charge gap and Hall conductivity vanishing due to a residual discrete particle-hole symmetry.Comment: 35 page

QCD Corrections to QED Vacuum Polarization

We compute QCD corrections to QED calculations for vacuum polarization in background magnetic fields. Formally, the diagram for virtual $e\bar{e}$ loops is identical to the one for virtual $q\bar{q}$ loops. However due to confinement, or to the growth of $\alpha_s$ as $p^2$ decreases, a direct calculation of the diagram is not allowed. At large $p^2$ we consider the virtual $q\bar{q}$ diagram, in the intermediate region we discuss the role of the contribution of quark condensates \left and at the low-energy limit we consider the $\pi^0$, as well as charged pion $\pi^+\pi^-$ loops. Although these effects seem to be out of the measurement accuracy of photon-photon laboratory experiments they may be relevant for $\gamma$-ray burst propagation. In particular, for emissions from the center of the galaxy (8.5 kpc), we show that the mixing between the neutral pseudo-scalar pion $\pi_0$ and photons renders a deviation from the power-law spectrum in the $TeV$ range. As for scalar quark condensates \left and virtual $q\bar{q}$ loops are relevant only for very high radiation density $\sim 300 MeV/fm^3$ and very strong magnetic fields of order $\sim 10^{14} T$.Comment: 15 pages, 4 figures; Final versio

Magnetic Catalysis: A Review

We give an overview of the magnetic catalysis phenomenon. In the framework of quantum field theory, magnetic catalysis is broadly defined as an enhancement of dynamical symmetry breaking by an external magnetic field. We start from a brief discussion of spontaneous symmetry breaking and the role of a magnetic field in its a dynamics. This is followed by a detailed presentation of the essential features of the phenomenon. In particular, we emphasize that the dimensional reduction plays a profound role in the pairing dynamics in a magnetic field. Using the general nature of underlying physics and its robustness with respect to interaction types and model content, we argue that magnetic catalysis is a universal and model-independent phenomenon. In support of this claim, we show how magnetic catalysis is realized in various models with short-range and long-range interactions. We argue that the general nature of the phenomenon implies a wide range of potential applications: from certain types of solid state systems to models in cosmology, particle and nuclear physics. We finish the review with general remarks about magnetic catalysis and an outlook for future research.Comment: 37 pages, to appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Yee. Version 2: references adde

ОСНОВНЫЕ НАПРАВЛЕНИЯ СЕЛЕКЦИОННОЙ РАБОТЫ С САДОВЫМИ РОЗАМИ В УСЛОВИЯХ ЮЖНОГО БЕРЕГА КРЫМА

The article presents the analysis of breeding work with garden roses, carried out in the Nikitsky Botanical Gardens (NBG) from 1824 to the present time. There are three main historical stages, which have different breeding tasks, as well as methods of work: the first stage is connected with the work of N.A. Hartwiss, the second stage – N.D. Kostetsky and the third one – V.N. Klimenko, Z.K. Klimenko and K.I. Zykov. The most significant breeding achievements of the NBG’s rose breeders are indicated. Based on the analysis of the results of the introduction study of garden roses in the NBG, the main features of garden roses cultivation in the Southern Coast of the Crimea (SCC) are specified and the requirements for cultivars created for these conditions are determined. It is established that currently in the breeding work with roses in the NBG, there are four main directions. The first direction is the creation of cultivars with multiple long flowering, the total duration of which can exceed 200 days. A cultivar must endure difficult xerothermic conditions of the Southern Coast in July – August without losing of decorative value. The second task is the selection work with garden groups that are difficult to cultivate in the more northern areas. Among them, under conditions of the SCC, there are highly promising garden groups of miniature and climbing roses. The third direction of breeding is to increase resistance to major fungal diseases affecting roses under the conditions of the SCC. The basic breeding methods to achieve this objective are given. The fourth research line is the creation of cultivars with a strong aroma. These cultivars can be used in aerophytotherapeutic rosaries, arrangement of which in the SCC is relevant in connection with the development of the resort industry.В статье представлен анализ селекционной работы с садовыми розами, проводимой в Никитском ботаническом саду (НБС) с 1824 г и до настоящего времени. Выделены три основных исторических этапа (первый связан с работой Н.А. Гартвиса, второй – Н.Д. Костецкого, третий – В.Н. Клименко, З.К. Клименко и К.И. Зыкова), отличающиеся селекционными задачами, а также методами работы. Указаны наиболее значимые селекционные достижения селекционеров роз НБС. На основании анализа результатов интродукционного изучения садовых роз в НБС сформулированы основные особенности культивирования садовых роз в условиях Южного берега Крыма (ЮБК) и определены требования к сортам, создаваемым для этих условий. Установлено, что в настоящее время в селекционной работе с розами в НБС существуют четыре основных направления. Первое направление – это создание сортов с многократным, продолжительным цветением, суммарная продолжительность которого может превышать 200 дней. При этом сорт должен переносить сложные ксеротермические условия ЮБК в июле – августе без снижения декоративности. Второй задачей является селекционная работа с садовыми группами, которые трудны в культивировании в более северных районах. Из их числа в условиях ЮБК высоко перспективными являются садовые группы миниатюрных и плетистых роз. Третьим направлением селекции является повышение устойчивости к основным грибным болезням, поражающим розы в условиях ЮБК. Приведены основные селекционные методы, позволяющие достичь этой цели. Четвертое направление – создание сортов с сильным ароматом. Такие сорта могут использоваться в аэрофитотерапевтических розариях, устройство которых на ЮБК актуально в связи с развитием курортной индустрии