Nonlinear Modulation of Multi-Dimensional Lattice Waves

The equations governing weakly nonlinear modulations of $N$-dimensional lattices are considered using a quasi-discrete multiple-scale approach. It is found that the evolution of a short wave packet for a lattice system with cubic and quartic interatomic potentials is governed by generalized Davey-Stewartson (GDS) equations, which include mean motion induced by the oscillatory wave packet through cubic interatomic interaction. The GDS equations derived here are more general than those known in the theory of water waves because of the anisotropy inherent in lattices. Generalized Kadomtsev-Petviashvili equations describing the evolution of long wavelength acoustic modes in two and three dimensional lattices are also presented. Then the modulational instability of a $N$-dimensional Stokes lattice wave is discussed based on the $N$-dimensional GDS equations obtained. Finally, the one- and two-soliton solutions of two-dimensional GDS equations are provided by means of Hirota's bilinear transformation method.Comment: Submitted to PR

Analysis of the Microbiome of Human Lungs and Respiratory System in Lung Disorders: a Review

Микробиота легочной системы способна оказывать значимое влияние на стабильность структуры и функциональную активность легких. Инициация и прогрессирование некоторых заболеваний легких зависит от патогенных факторов, экспрессируемых легочной микробиотой, и состояния дисбиоза в целом. Метагеномные исследования, основанные на секвенировании генов 16S рРНК, позволили получить актуальные данные о составе легочной микробиоты. Гены 16S рРНК состоят из 9 вариабельных участков (V1- V9). Определение более консервативных в эволюционном плане участков последовательностей 16S рРНК гена позволяет относить исследуемые геномы бактерий к таксонам более высокого порядка, в то время как получение информации о менее консервативных участках позволяет определять принадлежность бактерий к роду или виду. В настоящее время также активно развивается метатранскриптомика, основанная на оценке числа копий транскриптов легочной микробиоты. Существование разнообразия и избыточности генов, а также вариабельность их активности в разных условиях предполагает использование таких высокопроизводительных технологий, как секвенирование РНК и методы параллельного секвенирования. Полученные данные по метатранскриптомному анализу в значительной степени дополняют результаты метагеномных исследований, в то же время предполагается, что метатранскриптомный подход более информативен, что касается исследований функциональных взаимодействий между микробиотой и организмом-хозяином. Эти подходы предполагают оценку биологической активности различных компонентов микробиома в норме и патологии. В обзоре рассмотрены методические особенности применения метагеномного анализа, а также метатранскриптомных исследований при некоторых тяжелых заболеваниях легочной системы (рак легкого, хроническая обструктивная болезнь легких, астма и муковисцидоз)The structural stability of the respiratory system and the functional activity of the lungs are influenced by the local microflora. The initiation and the progression of some lung diseases are determined by pathogenic factors produced by the lung microbiota and the dysbiotic conditions in general. Metagenomic studies based on sequencing of the genes for 16S ribosomal RNA have been used to collect direct data on the composition of the lung microbiota. 16S rRNA genes consist of 9 variable regions (V1-V9). By determining highly conservative 16S rRNA regions, bacterial genomes can be assigned to higher-level taxa, while based on information about less conservative regions of these genes, the genera or species of bacteria can be identified. Metatranscriptomics, which is based on estimating the number of copies of transcripts from the pulmonary microbiota, is also rapidly developing. The diversity and redundancy of genes and their variable activity in different conditions are prerequisites for using high-performance technologies such as RNA‑seq and parallel sequencing methods. The metatranscriptomic analysis data significantly complement metagenomics; at the same time, metatranscriptomics is assumed to be more informative in examination of functional interactions between microbiome and host organism. These approaches offer an estimation of the biological activity of different components in the microbiome under normal and pathological conditions. This review summarizes the results of recent metagenomic and metatranscriptomic studies regarding a number of serious diseases of the respiratory system (lung cancer, chronic obstructive lung disease, asthma, and cystic fibrosis

Search for rare or forbidden decays of the D0 meson

We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type D0→h'−h−ℓ'+ℓ+ and D0→h'−h+ℓ'±ℓ∓, where h and h′ represent a K or π meson and ℓ and ℓ′ an electron or muon. The analysis is based on 468 fb−1 of e+e− annihilation data collected at or close to the Υ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes, and we establish 90% confidence level upper limits on the branching fractions in the range (1.0–30.6)×10−7. The limits are between 1 and 3 orders of magnitude more stringent than previous measurements.publishedVersio

Measurements of the absolute branching fractions of B± →k±Xc c

A study of the two-body decays B±→Xc¯cK±, where Xc¯c refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb−1. The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B+→X(3872)K+ at the 3σ level. The absolute branching fraction B[B+→X(3872)K+]=[2.1±0.6(stat)±0.3(syst)]×10−4 is measured for the first time. It follows that B[X(3872)→J/ψπ+π−]=(4.1±1.3)%, supporting the hypothesis of a molecular component for this resonance.publishedVersio

Light meson spectroscopy from Dalitz plot analyses of ηc decays to η0 K+K− , η0 π + π − , and ηπ + π − produced in two-photon interactions

We study the processes γγ→ηc→η′K+K−, η′π+π−, and ηπ+π− using a data sample of 519  fb−1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− collider at center-of-mass energies at and near the Υ(nS) (n=2, 3, 4) resonances. This is the first observation of the decay ηc→η′K+K− and we measure the branching fraction Γ(ηc→η′K+K−)/(Γ(ηc→η′π+π−)=0.644±0.039stat±0.032sys. Significant interference is observed between γγ→ηc→ηπ+π− and the nonresonant two-photon process γγ→ηπ+π−. A Dalitz plot analysis is performed of ηc decays to η′K+K−, η′π+π−, and ηπ+π−. Combined with our previous analysis of ηc→K¯Kπ, we measure the K∗0(1430) parameters and the ratio between its η′K and πK couplings. The decay ηc→η′π+π− is dominated by the f0(2100) resonance, also observed in J/ψ radiative decays. A new a0(1700)→ηπ resonance is observed in the ηc→ηπ+π− channel. We also compare ηc decays to η and η′ final states in association with scalar mesons as they relate to the identification of the scalar glueball.publishedVersio

Recent Results on Two-Photon Physics at BaBar

The authors present measurements of the {gamma}{gamma}* {yields} {pi}{sup 0} transition form factor for the momentum transfer range Q{sup 2} = 4-40 GeV{sup 2} and the {gamma}{gamma}* {yields} {eta}{sub c} transition form factor for the range Q{sup 2} = 2-50 GeV{sup 2}. The results of the measurement of the {eta}{sub c} mass, total and two-photon widths are also presented