Solitary and compact-like shear waves in the bulk of solids

We show that a model proposed by Rubin, Rosenau, and Gottlieb [J. Appl. Phys. 77 (1995) 4054], for dispersion caused by an inherent material characteristic length, belongs to the class of simple materials. Therefore, it is possible to generalize the idea of Rubin, Rosenau, and Gottlieb to include a wide range of material models, from nonlinear elasticity to turbulence. Using this insight, we are able to fine-tune nonlinear and dispersive effects in the theory of nonlinear elasticity in order to generate pulse solitary waves and also bulk travelling waves with compact support

The Mating System of the Wild-to-Domesticated Complex of Gossypium hirsutum L. Is Mixed

The domestication syndrome of many plants includes changes in their mating systems. The evolution of the latter is shaped by ecological and genetic factors that are particular to an area. Thus, the reproductive biology of wild relatives must be studied in their natural distribution to understand the mating system of a crop species as a whole. Gossypium hirsutum (upland cotton) includes both domesticated varieties and wild populations of the same species. Most studies on mating systems describe cultivated cotton as self-pollinated, while studies on pollen dispersal report outcrossing; however, the mating system of upland cotton has not been described as mixed and little is known about its wild relatives. In this study we selected two wild metapopulations for comparison with domesticated plants and one metapopulation with evidence of recent gene flow between wild relatives and the crop to evaluate the mating system of cotton’s wild-to-domesticated complex. Using classic reproductive biology methods, our data demonstrate that upland cotton presents a mixed mating system throughout the complex. Given cotton’s capacity for outcrossing, differences caused by the domestication process in cultivated individuals can have consequences for its wild relatives. This characterization of the diversity of the wild relatives in their natural distribution, as well as their interactions with the crop, will be useful to design and implement adequate strategies for conservation and biosecurity

Radiation temperature measurements in laser-heated hohlraums

Two x-ray spectrographs have been used on the Trident laser at LANL to monitor the radiation temperature of small Au hohlraums. The cylindrical targets are smaller than 1 mm. The x radiation produced by {approximately} 400 J of 0.53-{micro}m laser light is detected with a 7-channel VNIIEF soft-x-ray spectrometer. Each channel employs a multi-layer mirror and a filter to limit the channel bandwidth to 1--3% of the channel energy. X rays are detected with calibrated Al x-ray diodes. A second spectrometer is based on a free-standing Au transmission grating for spectral dispersion and a multi-channel diamond photo-conductive device detector. The small hohlraum results are consistent with radiation temperatures exceeding 100 eV. Simple computer modeling shows that late in the plasma discharge, radiation of this temperature is emitted from the target

Close Packing of Atoms, Geometric Frustration and the Formation of Heterogeneous States in Crystals

To describe structural peculiarities in inhomogeneous media caused by the tendency to the close packing of atoms a formalism based on the using of the Riemann geometry methods (which were successfully applied lately to the description of structures of quasicrystals and glasses) is developed. Basing on this formalism we find in particular the criterion of stability of precipitates of the Frank-Kasper phases in metallic systems. The nature of the ''rhenium effect'' in W-Re alloys is discussed.Comment: 14 pages, RevTex, 2 PostScript figure

Влияние кровенаполнения сосудов головного мозга на гемодинамику глаза и течение глаукомного процесса

PURPOSE: To investigate the effect of cerebral blood flow on ocular haemodynamics in control subjects and in patients with primary open-angle glaucoma (POAG), depending on the age and dynamics of glaucoma process. METHODS: Blood filling of cerebral and ocular vessels was investigated with the use of rheoencephalography and rheoophthalmography in 115 patients with POAG and in 31 subjects of the control group with no signs of glaucoma, including 33 patients (66 eyes) with non-progressive glaucoma and 82 patients (164 eyes) with progressive POAG. The age range was 50-89 years. Intraocular pressure in all subjects was between 19-21mm Hg. Cerebral hemodynamics was analyzed by the intensity of blood vessel pulse in the cerebral vessels (rheographic index), by the maximum speed of blood during the periods of rapid and slow blood flow, as well as the dicrotic and diastolic indices. Intraocular perfusion was analyzed by the following parameters: largest pulse volume, time of rapid and slow blood flow in ocular vessels, Kedrov’s pulse volume and Yantchu rheographic coefficient. RESULTS: Control group members aged 70-79 and 80-89 showed a significant decrease of blood filling of cerebral and ocular vessels (p=0.02). In patients’ age groups 50-59 and 60-69, with nonprogressive course of POAG no significant decrease of hemodynamics of cerebral and ocular vessels has been revealed as compared to the control group (p=0.02). In age groups of 70-79, 80-89 there was a decrease in blood flow speed in cerebral and ocular vessels. In patients with progressive glaucoma a significant decrease in cerebral and ocular hemodynamics parameters has been revealed starting at the age of 50-59 with further deterioration in the following age groups: 60-69, 70-79, 80-89 (p=0.02). CONCLUSION: A correlation between ocular blood supply and cerebral hemodynamics has been established. A more prominent correlation is detected in patients with progressive course of POAG (p=0.01, r=0.97).ЦЕЛЬ. Исследовать влияние пульсового кровенаполнения сосудов головного мозга на гемодинамику глаза у лиц контрольной группы и у больных с первичной открытоугольной глаукомой (ПОУГ) в зависимости от возраста и динамики глаукомного процесса. МАТЕРИАЛЫ И МЕТОДЫ. Исследование проводили с помощью реоэнцефалографии и реоофтальмографии. Обследованы 115 больных ПОУГ и 31 человек контрольной группы без признаков глаукомы, в возрасте от 50 до 89 лет. Тонометрическое внутриглазное давление у всех исследуемых находилось в пределах 19-21 мм рт.ст. Со стабилизированным течением ПОУГ было 33 больных (66 глаз), с нестабилизированным течением - 82 больных (164 глаза). Церебральную гемодинамику анализировали по интенсивности пульсового кровенаполнения сосудов головного мозга - реографическому индексу, по максимальной скорости периода быстрого и медленного кровенаполнения, по дикротическому и диастолическому индексам. Внутриглазное кровенаполнение анализировали по величине пульсового кровенаполнения, времени быстрого и медленного кровенаполнения сосудов глаза, пульсовому объему по Кедрову и реографическому коэффициенту по Янтчу. РЕЗУЛЬТАТЫ. У лиц контрольной группы в возрасте 70-79 и 80-89 лет выявлено снижение кровенаполнения сосудов головного мозга и глаза (p=0,02). У больных со стабилизированным течением ПОУГ во всех возрастных группах выявлено незначительное снижение гемодинамики в сосудах головного мозга и глаза и оно недостоверно (p=0,06-0,08). При нестабилизированном течении ПОУГ обнаружено существенное снижение кровенаполнения в церебральных и интраокулярных сосудах у больных в возрасте 50-59 лет, эти показатели продолжали ухудшаться в возрастных группах 60-69, 70-79 и 80-89 лет (p=0,01). ЗАКЛЮЧЕНИЕ. Выявлено существенное влияние кровенаполнения сосудов головного мозга на гемодинамику глаза и тяжесть течения глаукомы, особенно у больных с нестабилизированным течением ПОУГ, у которых имеется достоверное снижение кровоснабжения глаза во всех возрастных группах (p=0,01, r=0,97)

Shock Wave Structure in a Strongly Nonlinear Granular Lattice with Viscous Dissipation

The shock wave structure in a one-dimensional lattice (e.g. granular chain) with a power law dependence of force on displacement between particles with viscous dissipation is considered and compared to the corresponding long wave approximation. A dissipative term depending on the relative velocity between neighboring particles is included in the discrete model to investigate its influence on the shape of steady shock profiles. The critical viscosity coefficient is obtained from the long-wave approximation for arbitrary values of the exponent n and denotes the transition from an oscillatory to a monotonic shock profile in stronly nonlinear systems. The expression for the critical viscosity coefficient converges to the known equation for the critical viscosity in the weakly nonlinear case. Values of viscosity based on this expression are comparable to the values obtained in the numerical analysis of a discrete particle lattice with a Herzian contact interaction corresponding to n = 3/2. An initial disturbance in a discrete system approaches a stationary shock profile after traveling a short distance that is comparable to the width of the leading pulse of a stationary shock front. The shock front width is minimized when the viscosity is equal to its critical value.Comment: 20 pages, 6 figure

Automatically extracting functionally equivalent proteins from SwissProt

In summary, FOSTA provides an automated analysis of annotations in UniProtKB/Swiss-Prot to enable groups of proteins already annotated as functionally equivalent, to be extracted. Our results demonstrate that the vast majority of UniProtKB/Swiss-Prot functional annotations are of high quality, and that FOSTA can interpret annotations successfully. Where FOSTA is not successful, we are able to highlight inconsistencies in UniProtKB/Swiss-Prot annotation. Most of these would have presented equal difficulties for manual interpretation of annotations. We discuss limitations and possible future extensions to FOSTA, and recommend changes to the UniProtKB/Swiss-Prot format, which would facilitate text-mining of UniProtKB/Swiss-Prot

Interpreting 16S metagenomic data without clustering to achieve sub-OTU resolution

The standard approach to analyzing 16S tag sequence data, which relies on clustering reads by sequence similarity into Operational Taxonomic Units (OTUs), underexploits the accuracy of modern sequencing technology. We present a clustering-free approach to multi-sample Illumina datasets that can identify independent bacterial subpopulations regardless of the similarity of their 16S tag sequences. Using published data from a longitudinal time-series study of human tongue microbiota, we are able to resolve within standard 97% similarity OTUs up to 20 distinct subpopulations, all ecologically distinct but with 16S tags differing by as little as 1 nucleotide (99.2% similarity). A comparative analysis of oral communities of two cohabiting individuals reveals that most such subpopulations are shared between the two communities at 100% sequence identity, and that dynamical similarity between subpopulations in one host is strongly predictive of dynamical similarity between the same subpopulations in the other host. Our method can also be applied to samples collected in cross-sectional studies and can be used with the 454 sequencing platform. We discuss how the sub-OTU resolution of our approach can provide new insight into factors shaping community assembly.Comment: Updated to match the published version. 12 pages, 5 figures + supplement. Significantly revised for clarity, references added, results not change

Where is the UK's pollinator biodiversity? The importance of urban areas for flower-visiting insects

Insect pollinators provide a crucial ecosystem service, but are under threat. Urban areas could be important for pollinators, though their value relative to other habitats is poorly known. We compared pollinator communities using quantified flower-visitation networks in 36 sites (each 1 km2) in three landscapes: urban, farmland and nature reserves. Overall, flower-visitor abundance and species richness did not differ significantly between the three landscape types. Bee abundance did not differ between landscapes, but bee species richness was higher in urban areas than farmland. Hoverfly abundance was higher in farmland and nature reserves than urban sites, but species richness did not differ significantly. While urban pollinator assemblages were more homogeneous across space than those in farmland or nature reserves, there was no significant difference in the numbers of rarer species between the three landscapes. Network-level specialization was higher in farmland than urban sites. Relative to other habitats, urban visitors foraged from a greater number of plant species (higher generality) but also visited a lower proportion of available plant species (higher specialization), both possibly driven by higher urban plant richness. Urban areas are growing, and improving their value for pollinators should be part of any national strategy to conserve and restore pollinators