Random and exhaustive generation of permutations and cycles

In 1986 S. Sattolo introduced a simple algorithm for uniform random generation of cyclic permutations on a fixed number of symbols. This algorithm is very similar to the standard method for generating a random permutation, but is less well known. We consider both methods in a unified way, and discuss their relation with exhaustive generation methods. We analyse several random variables associated with the algorithms and find their grand probability generating functions, which gives easy access to moments and limit laws.Comment: 9 page

Климатические особенности и статистические оценки изменения элементов климата в районах вечной мерзлоты на территории севера Западной Сибири

Актуальность работы связана с необходимостью оценки изменений климата, влияющих на многолетнюю мерзлоту, в связи с возможным увеличением выбросов парниковых газов и увеличения аварийности на объектах промышленной, в том числе и нефтегазовой, инфраструктуры при таянии многолетнемерзлых пород. Цель работы: исследование современных изменений характеристик климата, непосредственно влияющих на термическое состояние почвогрунтов в районах распространения многолетней мерзлоты севера Западной Сибири. Методы исследования. Анализ многолетних изменений метеорологических данных включал в себя проверку нулевых гипотез о случайности и однородности рядов наблюдений и наличия тренда. Проверка на однородность осуществлялась с помощью теста Аббе, на случайность - критерием Питмена, на наличие тренда производилась с помощью критерия инверсий. Вывод о неслучайном изменении или нарушении однородности рядов соответствовал условию, когда расчетная статистика превышала соответствующее критическое значение при уровне значимости 0,05. Результаты. Рассмотрены особенности климата севера Западной Сибири и его изменчивость в последние годы. Исследованы изменения температуры воздуха и почвогрунтов на глубинах 160 и 320 см, продолжительность прямой солнечной радиации, суммы атмосферных осадков и высоты снежного покрова на основе инструментальных данных за последние 35 лет. В результате статистического анализа установлено сохранение темпов роста температуры воздуха в теплое время года, увеличение температуры почвогрунтов в течение всего года, выявлен зональный характер изменения суммы атмосферных осадков и снежного покрова. Микроклиматические изменения характеристик метеорологических величин могут искажать реальную картину изменения климата.The relevance of the research is related to the necessity to assess climate changes affecting the permafrost due to the possible growth of greenhouse gas emissions and increase of accident rate in industrial, oil and gas infrastructure at permafrost thawing. The aim of the research is to estimate the current changes in climate characteristics, which affect directly the thermal state of soils in permafrost areas in the north of Western Siberia. Methods. Analysis of long-term changes of meteorological data consisted of tests of null hypothesis of randomness and homogeneity of observation series and trend presence. The homogeneity test was carried out using the Abbe test, the test of randomness was carried out by Pitman criterion, the trend presence was checked using the criterion of inversions. The conclusion on nonrandom change or violation of the homogeneity of rows corresponded to the condition, when the modulus of the estimated statistics exceeded the corresponding critical value at significance level of 0,05. Results. The paper considers the climatic features in the north of Western Siberia and its variability in recent years. The analysis of temperature changes of air and soil at depths of 160 and 320 cm, the amount of precipitation and snow cover based on the instrumental data for the last 35 years has shown that air temperature continues rising in the warmer months, soil temperature increases throughout the year. The authors have revealed zonal character of changes in the amount of precipitation and snow cover. Microclimatic changes in characteristic of meteorological values can distort the real picture of climate change

Mlh2 is an accessory factor for DNA mismatch repair in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, the essential mismatch repair (MMR) endonuclease Mlh1-Pms1 forms foci promoted by Msh2-Msh6 or Msh2-Msh3 in response to mispaired bases. Here we analyzed the Mlh1-Mlh2 complex, whose role in MMR has been unclear. Mlh1-Mlh2 formed foci that often colocalized with and had a longer lifetime than Mlh1-Pms1 foci. Mlh1-Mlh2 foci were similar to Mlh1-Pms1 foci: they required mispair recognition by Msh2-Msh6, increased in response to increased mispairs or downstream defects in MMR, and formed after induction of DNA damage by phleomycin but not double-stranded breaks by I-SceI. Mlh1-Mlh2 could be recruited to mispair-containing DNA in vitro by either Msh2-Msh6 or Msh2-Msh3. Deletion of MLH2 caused a synergistic increase in mutation rate in combination with deletion of MSH6 or reduced expression of Pms1. Phylogenetic analysis demonstrated that the S. cerevisiae Mlh2 protein and the mammalian PMS1 protein are homologs. These results support a hypothesis that Mlh1-Mlh2 is a non-essential accessory factor that acts to enhance the activity of Mlh1-Pms1

Suspension-adapted Chinese hamster ovary-derived cells expressing green fluorescent protein as a screening tool for biomaterials

Synthetic biomaterials play an important role in regenerative medicine. To be effective they must support cell attachment and proliferation in addition to being non-toxic and non-immunogenic. We used a suspension-adapted Chinese hamster ovary-derived cell line expressing green fluorescent protein (GFP) to assess cell attachment and growth on synthetic biomaterials by direct measurement of GFP-specific fluorescence. To simplify operations, all cell cultivation steps were performed in orbitally-shaken, disposable containers. Comparative studies between this GFP assay and previously established cell quantification assays demonstrated that this novel approach is suitable for rapid screening of a large number of samples. Furthermore the utility of our assay system was confirmed by evaluation of cell growth on three polyvinylidene fluoride polymer scaffolds that differed in pore diameter and drawing conditions. The data presented here prove the general utility of GFP-expressing cell lines and orbital shaking technology for the screening of biomaterials for tissue engineering application

Divergence in Dialogue

Copyright: 2014 Healey et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This work was supported by the Economic and Social Research Council (ESRC; http://www.esrc.ac.uk/) through the DynDial project (Dynamics of Conversational Dialogue, RES-062-23-0962) and the Engineering and Physical Sciences Research Council (EPSRC; http://www.epsrc.ac.uk/) through the RISER project (Robust Incremental Semantic Resources for Dialogue, EP/J010383/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Self-assembly of ordered wurtzite/rock salt heterostructures—A new view on phase separation in MgxZn1−xO

The self-assembled formation of ordered, vertically stacked rocksalt/wurtzite Mg x Zn 1−xO heterostructures by planar phase separation is shown. These heterostructures form quasi “natural” two-dimensional hetero-interfaces between the different phases upon annealing of MgO-oversaturated wurtzite Mg x Zn 1−xO layers grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. The optical absorption spectra show a red shift simultaneous with the appearance of a cubic phase upon annealing at temperatures between 900 °C and 1000 °C. Transmission electron microscopy reveals that these effects are caused by phase separation leading to the formation of a vertically ordered rock salt/wurtzite heterostructures. To explain these observations, we suggest a phase separation epitaxy model that considers this process being initiated by the formation of a cubic (Mg,Zn)Al2O4 spinel layer at the interface to the sapphire substrate, acting as a planar seed for the epitaxial precipitation of rock salt Mg x Zn 1−xO. The equilibrium fraction x of magnesium in the resulting wurtzite (rock salt) layers is approximately 0.15 (0.85), independent of the MgO content of the as-grown layer and determined by the annealing temperature. This model is confirmed by photoluminescence analysis of the resulting layer systems after different annealing temperatures. In addition, we show that the thermal annealing process results in a significant reduction in the density of edge- and screw-type dislocations, providing the possibility to fabricate high quality templates for quasi-homoepitaxial growth

The Role of Bile in the Regulation of Exocrine Pancreatic Secretion

As early as 1926 Mellanby (1) was able to show that introduction of bile into the duodenum of anesthetized cats produces a copious flow of pancreatic juice. In conscious dogs, Ivy & Lueth (2) reported, bile is only a weak stimulant of pancreatic secretion. Diversion of bile from the duodenum, however, did not influence pancreatic volume secretion stimulated by a meal (3,4). Moreover, Thomas & Crider (5) observed that bile not only failed to stimulate the secretion of pancreatic juice but also abolished the pancreatic response to intraduodenally administered peptone or soap

A global database of lake surface temperatures collected by in situ and satellite methods from 1985–2009

Global environmental change has influenced lake surface temperatures, a key driver of ecosystem structure and function. Recent studies have suggested significant warming of water temperatures in individual lakes across many different regions around the world. However, the spatial and temporal coherence associated with the magnitude of these trends remains unclear. Thus, a global data set of water temperature is required to understand and synthesize global, long-term trends in surface water temperatures of inland bodies of water. We assembled a database of summer lake surface temperatures for 291 lakes collected in situ and/or by satellites for the period 1985–2009. In addition, corresponding climatic drivers (air temperatures, solar radiation, and cloud cover) and geomorphometric characteristics (latitude, longitude, elevation, lake surface area, maximum depth, mean depth, and volume) that influence lake surface temperatures were compiled for each lake. This unique dataset offers an invaluable baseline perspective on global-scale lake thermal conditions as environmental change continues

Software Model Checking with Explicit Scheduler and Symbolic Threads

In many practical application domains, the software is organized into a set of threads, whose activation is exclusive and controlled by a cooperative scheduling policy: threads execute, without any interruption, until they either terminate or yield the control explicitly to the scheduler. The formal verification of such software poses significant challenges. On the one side, each thread may have infinite state space, and might call for abstraction. On the other side, the scheduling policy is often important for correctness, and an approach based on abstracting the scheduler may result in loss of precision and false positives. Unfortunately, the translation of the problem into a purely sequential software model checking problem turns out to be highly inefficient for the available technologies. We propose a software model checking technique that exploits the intrinsic structure of these programs. Each thread is translated into a separate sequential program and explored symbolically with lazy abstraction, while the overall verification is orchestrated by the direct execution of the scheduler. The approach is optimized by filtering the exploration of the scheduler with the integration of partial-order reduction. The technique, called ESST (Explicit Scheduler, Symbolic Threads) has been implemented and experimentally evaluated on a significant set of benchmarks. The results demonstrate that ESST technique is way more effective than software model checking applied to the sequentialized programs, and that partial-order reduction can lead to further performance improvements.Comment: 40 pages, 10 figures, accepted for publication in journal of logical methods in computer scienc

A paradox of syntactic priming: why response tendencies show priming for passives, and response latencies show priming for actives

Speakers tend to repeat syntactic structures across sentences, a phenomenon called syntactic priming. Although it has been suggested that repeating syntactic structures should result in speeded responses, previous research has focused on effects in response tendencies. We investigated syntactic priming effects simultaneously in response tendencies and response latencies for active and passive transitive sentences in a picture description task. In Experiment 1, there were priming effects in response tendencies for passives and in response latencies for actives. However, when participants' pre-existing preference for actives was altered in Experiment 2, syntactic priming occurred for both actives and passives in response tendencies as well as in response latencies. This is the first investigation of the effects of structure frequency on both response tendencies and latencies in syntactic priming. We discuss the implications of these data for current theories of syntactic processing