Structured Coalescent Processes on Different Time Scales

It is demonstrated that the structured coalescent model can readily be extended to include phenomena such as partial selfing and background selection through the use of an approximation based on separation of time scales. A model that includes these phenomena, as well as geographic subdivision and linkage to a polymorphism maintained either by local adaptation or by balancing selection, is derived, and the expected coalescence time for a pair of genes is calculated. It is found that background selection reduces coalescence times within subpopulations and allelic classes, leading to a high degree of apparent differentiation. Extremely high levels of subpopulation differentiation are also expected for regions of the genome surrounding loci important in local adaptation. These regions will be wider the stronger the local selection, and the higher the selfing rate.     

Genomic Evidence of Rapid and Stable Adaptive Oscillations over Seasonal Time Scales in Drosophila

In many species, genomic data have revealed pervasive adaptive evolution indicated by the fixation of beneficial alleles. However, when selection pressures are highly variable along a species'' range or through time adaptive alleles may persist at intermediate frequencies for long periods. So called “balanced polymorphisms” have long been understood to be an important component of standing genetic variation, yet direct evidence of the strength of balancing selection and the stability and prevalence of balanced polymorphisms has remained elusive. We hypothesized that environmental fluctuations among seasons in a North American orchard would impose temporally variable selection on Drosophila melanogaster that would drive repeatable adaptive oscillations at balanced polymorphisms. We identified hundreds of polymorphisms whose frequency oscillates among seasons and argue that these loci are subject to strong, temporally variable selection. We show that these polymorphisms respond to acute and persistent changes in climate and are associated in predictable ways with seasonally variable phenotypes. In addition, our results suggest that adaptively oscillating polymorphisms are likely millions of years old, with some possibly predating the divergence between D. melanogaster and D. simulans. Taken together, our results are consistent with a model of balancing selection wherein rapid temporal fluctuations in climate over generational time promotes adaptive genetic diversity at loci underlying polygenic variation in fitness related phenotypes.     

Liquidity Spillover in International Stock Markets through Distinct Time Scales

This paper identifies liquidity spillovers through different time scales based on a wavelet multiscaling method. We decompose daily data from U.S., British, Brazilian and Hong Kong stock markets indices in order to calculate the scale correlation between their illiquidities. The sample is divided in order to consider non-crisis, sub-prime crisis and Eurozone crisis. We find that there are changes in correlations of distinct scales and different periods. Association in finest scales is smaller than in coarse scales. There is a rise on associations in periods of crisis. In frequencies, there is predominance for significant distinctions involving the coarsest scale, while for crises periods there is predominance for distinctions on the finest scale.     

Evidence for Two Main Domestication Trajectories in Saccharomyces cerevisiae Linked to Distinct Bread-Making Processes

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Modeling of Proton Transfer in Polymer Electrolyte Membranes on Different Time and Length Scales

Polymer electrolyte membranes (PEMs) are key component materials in fuel cell technology. Understanding the relationship between the elementary acts of proton transport and the operation of the entire cell on different time and length scales is therefore particularly rewarding. We discuss the results of recent atomistic computer simulations of proton transport in porous PEMs. Different models cover the range from individual local proton hops to diffusion processes with polymer mobility included.     

Locally Adaptive Inversions Modulate Genetic Variation at Different Geographic Scales in a Seaweed Fly

Across a species range, multiple sources of environmental heterogeneity, at both small and large scales, create complex landscapes of selection, which may challenge adaptation, particularly when gene flow is high. One key to multidimensional adaptation may reside in the heterogeneity of recombination along the genome. Structural variants, like chromosomal inversions, reduce recombination, increasing linkage disequilibrium among loci at a potentially massive scale. In this study, we examined how chromosomal inversions shape genetic variation across a species range and ask how their contribution to adaptation in the face of gene flow varies across geographic scales. We sampled the seaweed fly Coelopa frigida along a bioclimatic gradient stretching across 10° of latitude, a salinity gradient, and a range of heterogeneous, patchy habitats. We generated a chromosome-level genome assembly to analyze 1,446 low-coverage whole genomes collected along those gradients. We found several large nonrecombining genomic regions, including putative inversions. In contrast to the collinear regions, inversions and low-recombining regions differentiated populations more strongly, either along an ecogeographic cline or at a fine-grained scale. These genomic regions were associated with environmental factors and adaptive phenotypes, albeit with contrasting patterns. Altogether, our results highlight the importance of recombination in shaping adaptation to environmental heterogeneity at local and large scales.     

Clinical Evidence for Three Distinct Gastric Cancer Subtypes: Time for a New Approach

Background

Recently, a new classification for gastric cancer (GC) has been proposed, based on Lauren''s histology and on anatomic tumour location, identifying three subtypes of disease: type 1 (proximal non diffuse GC), type 2 (diffuse GC) and type 3 (distal non diffuse GC). Aim of our analysis was to compare clinical outcome according to different GC subtypes (1,2,3) in metastatic GC patients receiving first-line chemotherapy.

Patients and Methods

Advanced GC pts treated with a first-line combination chemotherapy were included in our analysis. Pts were divided in three subgroups (type 1, type 2 and type 3) as previously defined.

Results

A total of 248 advanced GC pts were included: 45.2% belonged to type 2, 43.6% to type 3 and 11.2% to type 1. Patients received a fluoropyrimidine-based chemotherapy doublet or three drugs regimens including a platinum derivate and a fluoropyrimidine with the addition of an anthracycline, a taxane or mytomicin C. RR was higher in type 1 pts (RR = 46.1%) and type 3 (34,3%) compared to type 2 (20,4%), (p = 0.015). Type 2 presented a shorter PFS, median PFS = 4.2 months, compared to type 1, mPFS = 7.2 months, and type 3, mPFS = 5.9 months (p = 0.011) and also a shorter OS (p = 0.022).

Conclusions

Our analysis suggests that GC subtypes may be important predictors of benefit from chemotherapy in advanced GC patients. Future clinical trials should take in account these differences for a better stratification of patients.     

Reduction of Nonautonomous Population Dynamics Models with Two Time Scales

The purpose of this work is reviewing some reduction results to deal with systems of nonautonomous ordinary differential equations with two time scales. They could be included among the so-called approximate aggregation methods. The existence of different time scales in a system, together with some long-term features, are used to build up a simpler system governed by a lesser number of state variables. The asymptotic behavior of the latter system is then used to describe the asymptotic behaviour of the former one. The reduction results are stated in two particular but important cases: periodic systems and asymptotically autonomous systems. The reduction results are illustrated with the help of simple spatial SIS epidemic models including either periodic or asymptotically autonomous terms.     

Evidence Supporting the Recognition of Cole latent virus as a Distinct Carlavirus

Some molecular properties are described of Cole latent virus (CoLV), hitherto designated a tentative species of the Carlavirus genus. CoLV genomic RNA (Ribonucleic acid) of 8.3 Kb is polyadenylated. Two unencapsidated polyadenylated subgenomic RNAs (2.6 and 1.3 Kb) and three double-stranded RNAs (dsRNAs) (8.3, 2.6 and 1.3 Kbp), which are twice the size of the genomic and subgenomics ssRNAs, are produced in CoLV-infected plants; two additional dsRNAs (7.2 and 6.3 Kbp) were also detected in plant extracts. By using a Carlavirus specific primer and a CoLV cDNA, a-3'-terminus fragment of 116 bp was amplified; it had homology with the carlaviruses Potato virus M (62%), Hop latent virus (37%) and Blueberry scorch virus (36%) but no significant homology with 11 other carlaviruses. These results support the classification of CoLV as a distinct species of the Carlavirus genus.     

Spatial Heterogeneity and Soil Nitrogen Dynamics in a Burned Black Spruce Forest Stand: Distinct Controls at Different Scales

We evaluated spatial patterns of soil N and C mineralization, microbial community composition (phospholipid fatty acids), and local site characteristics (plant/forest floor cover, soil pH, soil %C and %N) in a 0.25-ha burned black spruce forest stand in interior Alaska. Results indicated that factors governing soil N and C mineralization varied at two different scales. In situ net N mineralization was autocorrelated with microbial community composition at relatively broad scales (∼ ∼8 m) and with local site characteristics (`site' axis 1 of non-metric scaling ordination) at relatively fine scales (2–4 m). At the scale of the individual core, soil moisture was the best predictor of in situ net N mineralization and laboratory C mineralization, explaining between 47 and 67% of the variation (p < 0.001). Ordination of microbial lipid data showed that bacteria were more common in severely burned microsites, whereas fungi were more common in low fire severity microsites. We conclude that C and N mineralization rates in this burned black spruce stand were related to different variables depending on the scale of analysis, suggesting the importance of considering multiple scales of variability among key drivers of C and N transformations.     

Adaptive Characteristics of Skiers with Different Types of Energy Supply of Skeletal Muscles to Graded Exercise and Athletic Training

Thirty-five skiers with different types of energy supply to skeletal muscle were studied over a one-year training cycle. The adaptive characteristics of the adolescent boys were assessed by Baevskii's index of stress in the body's regulatory systems (stress index) caused by exercise at high workloads (3 and 6 W/kg); by the physiological cost of the exercise; by the time to exhaustion at a moderate workload (1.5 W/kg) in a bicycle ergometer test; and by athletic results. The stress index, the physiological cost of exercise and their changes over a one-year training cycle were clearly correlated with the type of energy production. It was suggested that training brings into play genetically determined adaptive programs and that an increase in the functional capabilities during ontogenesis is under control of the genome and mainly determined by individual and typological features of the body.     

时标下具Hassell-Varley型功能性反应的捕食者-食饵系统的周期性(英文)

利用重合度理论中的连续性定理研究了时标下具Hassell-Varley型功能性反应的捕食者-食饵系统的周期性,得到周期解存在的充分条件,所得结果推广了已有文献中的相关结论.     

Adaptive Cluster Synchronization of Directed Complex Networks with Time Delays

This paper studied the cluster synchronization of directed complex networks with time delays. It is different from undirected networks, the coupling configuration matrix of directed networks cannot be assumed as symmetric or irreducible. In order to achieve cluster synchronization, this paper uses an adaptive controller on each node and an adaptive feedback strategy on the nodes which in-degree is zero. Numerical example is provided to show the effectiveness of main theory. This method is also effective when the number of clusters is unknown. Thus, it can be used in the community recognizing of directed complex networks.     

Inferring Synaptic Structure in Presence of Neural Interaction Time Scales

Biological networks display a variety of activity patterns reflecting a web of interactions that is complex both in space and time. Yet inference methods have mainly focused on reconstructing, from the network’s activity, the spatial structure, by assuming equilibrium conditions or, more recently, a probabilistic dynamics with a single arbitrary time-step. Here we show that, under this latter assumption, the inference procedure fails to reconstruct the synaptic matrix of a network of integrate-and-fire neurons when the chosen time scale of interaction does not closely match the synaptic delay or when no single time scale for the interaction can be identified; such failure, moreover, exposes a distinctive bias of the inference method that can lead to infer as inhibitory the excitatory synapses with interaction time scales longer than the model’s time-step. We therefore introduce a new two-step method, that first infers through cross-correlation profiles the delay-structure of the network and then reconstructs the synaptic matrix, and successfully test it on networks with different topologies and in different activity regimes. Although step one is able to accurately recover the delay-structure of the network, thus getting rid of any a priori guess about the time scales of the interaction, the inference method introduces nonetheless an arbitrary time scale, the time-bin dt used to binarize the spike trains. We therefore analytically and numerically study how the choice of dt affects the inference in our network model, finding that the relationship between the inferred couplings and the real synaptic efficacies, albeit being quadratic in both cases, depends critically on dt for the excitatory synapses only, whilst being basically independent of it for the inhibitory ones.     

Evidence that Mechanosensors with Distinct Biomechanical Properties Allow for Specificity in Mechanotransduction

Various cell types can sense and convert mechanical forces into biochemical signaling events through a process called mechanotransduction, and this process is often highly specific to the types of mechanical forces applied. However, the mechanism(s) that allow for specificity in mechanotransduction remain undefined. Thus, the goal of this study was to gain insight into how cells distinguish among specific types of mechanical information. To accomplish this goal, we determined if skeletal myoblasts can distinguish among differences in strain, strain rate, and strain-time integral (STI). Our results demonstrate that mechanically induced signaling through the c-jun N-terminal kinase 2 [JNK2] is elicited via a mechanism that depends on an interaction between the magnitude of strain and strain rate and is independent of STI. In contrast to JNK2, mechanically induced signaling through the ribosomal S6 kinase [p70(389)] is not strain rate sensitive, but instead involves a magnitude of strain and STI dependent mechanisms. Mathematical modeling also indicated that mechanically induced signaling through JNK2 and p70(389) can be isolated to separate viscous and elastic mechanosensory elements, respectively. Based on these results, we propose that skeletal myoblasts contain multiple mechanosensory elements with distinct biomechanical properties and that these distinct biomechanical properties provide a mechanism for specificity in mechanotransduction.     

不同时间服用比索洛尔对非杓型高血压血压的影响

目的:观察不同给药时间分别给予比索洛尔对非杓型原发性高血压患者的降压疗效和血压节律恢复的影响。方法:选取60例非杓型高血压患者,采取随机平行对照试验,观察比索洛尔(n=30)每日早晨(8:00)给药2.5-10mg、比索洛尔(n=30)每日夜间(20:00)给药2.5-10mg治疗8周后的降压疗效。结果:两种给药方法均能降低非杓型高血压患者的全天血压(P<0.05)。两种给药方法在白天的血压控制上无显著性差异(P>0.05),但在夜间血压的控制上夜间服药降压效果具有显著性差异(P<0.05)。夜间服药在血压节律恢复方面优于早晨服药(P<0.05),早晨服药组有10例恢复杓型,夜间服药组有19例恢复杓型。结论:比索洛尔的两种给药方式均能安全有效的降压,但对于非杓型高血压患者夜间服药优于早晨服药,更有利于血压节律的恢复。     

时标上一捕食二食饵系统的周期解（英文）

研究时标上一捕食二食饵系统.运用时标上Gaines和Mawhin的连续拓扑度定理,得到了系统存在周期解的新的充分条件.其研究方法可以广泛地运用来研究微分或者差分方程的周期解存在性问题.     

时标上脉冲混合动态系统实用渐近稳定性（英文）

在此篇论文中,采用Lyapunov直接法研究了一类时标脉冲混合动态系统关于两个测度的实用稳定性,进而将多个Lyapunov函数法推广到实用渐近稳定的研究中,并得到了相应的结论.     

Genetic Analysis of Invasive Plant Populations at Different Spatial Scales

Measuring genetic diversity requires selection of a spatial scale of analysis. Different levels of genetic structuring are revealed at different spatial scales, however, and the relative importance of factors driving genetic structuring varies along the spatial scale continuum. Unequal gene flow is a major factor determining genetic structure in plant populations at the local level, while the effect of selection imposed by environmental heterogeneity increases with the spatial scale of analysis. At a continental and global scale genetic structure of invasive plant populations is significantly affected by founder effect and propagule transport via human vectors. Although genetic analysis at one spatial scale provides only partial information about the invasion process, little published research reports such data for the same species at multiple scales. A multi-faceted approach to investigating the genetic structure of invasive plant species that incorporates sampling at different spatial and temporal scales would provide a more complete picture of the role of genetic forces in invasion.