Mycobacterium tuberculosis nucleoid-associated DNA-binding protein H-NS binds with high-affinity to the Holliday junction and inhibits strand exchange promoted by RecA protein

A number of studies have shown that the structure and composition of bacterial nucleoid influences many a processes related to DNA metabolism. The nucleoid-associated proteins modulate not only the DNA conformation but also regulate the DNA metabolic processes such as replication, recombination, repair and transcription. Understanding of how these processes occur in the context of Mycobacterium tuberculosis nucleoid is of considerable medical importance because the nucleoid structure may be constantly remodeled in response to environmental signals and/or growth conditions. Many studies have concluded that Escherichia coli H-NS binds to DNA in a sequence-independent manner, with a preference for A-/T-rich tracts in curved DNA; however, recent studies have identified the existence of medium- and low-affinity binding sites in the vicinity of the curved DNA. Here, we show that the M. tuberculosis H-NS protein binds in a more structure-specific manner to DNA replication and repair intermediates, but displays lower affinity for double-stranded DNA with relatively higher GC content. Notably, M. tuberculosis H-NS was able to bind Holliday junction (HJ), the central recombination intermediate, with substantially higher affinity and inhibited the three-strand exchange promoted by its cognate RecA. Likewise, E. coli H-NS was able to bind the HJ and suppress DNA strand exchange promoted by E. coli RecA, although much less efficiently compared to M. tuberculosis H-NS. Our results provide new insights into a previously unrecognized function of H-NS protein, with implications for blocking the genome integration of horizontally transferred genes by homologous and/or homeologous recombination.

Involvement of the Global Regulator H-NS in the Survival of Escherichia coli in Stationary Phase

Long-term batch cultures of Escherichia coli grown in nutrient-rich medium accumulate mutations that provide a growth advantage in the stationary phase (GASP). We have examined the survivors of prolonged stationary phase to identify loci involved in conferring a growth advantage and show that a mutation in the hns gene causing reduced activity of the global regulator H-NS confers a GASP phenotype under specific conditions. The hns-66 allele bears a point mutation within the termination codon of the H-NS open reading frame, resulting in a longer protein that is partially functional. Although isolated from a long-term stationary-phase culture of the parent carrying the rpoS819 allele that results in reduced RpoS activity, the hns-66 survivor showed a growth disadvantage in the early stationary phase (24 to 48 h) when competed against the parent. The hns-66 mutant is also unstable and reverts at a high frequency in the early stationary phase by accumulating second-site suppressor mutations within the ssrA gene involved in targeting aberrant proteins for proteolysis. The mutant was more stable and showed a moderate growth advantage in combination with the rpoS819 allele when competed against a 21-day-old parent. These studies show that H-NS is a target for mutations conferring fitness gain that depends on the genetic background as well as on the stage of the stationary phase.

有二次涡的激波边界层干扰流动的DPNS和NS方程计算

针对具有二次涡复杂分离再附现象的激波边界层干扰流动，数值地考察了扩散抛物化Navier-Stokes (DPNS)方程组的适用情况。壁面摩阻和压力、主涡和二次涡的涡高和涡长、分离再附位置以及流线图等特性的计算表明：DPNS方程组的数值结果均与NS方程组的数值结果很好相符。

Navier-Stokes(NS)方程组差分计算中的物理和网格尺度效应及NS方程组的简化

对于高Re数流动计算,在通常二阶精度NS差分格式和网格数条件下,存在某些粘性项落入修正微分方程截断误差项的问题。这类NS方程组计算实际是计算某种简化NS方程组,而且重复计算误差物理粘性项既浪费机时和内存,误差积累又会对数值解产生不可预测的影响。避免上述缺陷的办法一个是提高NS差分格式的精度 ,另一个是丢掉可能落入截断误差项的物理粘性项,把NS方程组简化为广义NS方程组。广义NS计算避免了误差物理粘性项误差积累对数值解的不可知影响,又可节省内存和机时,对高Re数流体工程计算很有好处。利用广义NS方程组计算超声速绕前向和后向台阶流动的结果表明:广义NS方程组与NS方程组的数值结果很好相符。

NS方程激波计算的摄动有限差分方法

摄动有限差分（PFD）方法从一阶迎风差分格式出发，将差分系数展开为网格步长的幂级数，通过提高修正微分方程的逼近精度来获得更高精度的差分格式。由于格式基于一阶迎风格式，因此具有迎风效应、网格节点少等特点。本文首先通过对Burgers方程的摄动差分格式的推导，将摄动有限差分格式引入时间相关法的计算，并构造了守恒形式的摄动有限差分格式，然后推广到一维Navier-Stokes方程组的计算。数值比较研究表明：本文构造的NS方程摄动有限差分格式具有比一阶迎风较高的精度和分辨率，而且保持了一阶迎风格式的无振荡性质。

Histoire d'un pays situe dans le nouveau monde, Nomme Amerique

Este é o tomo III da Coleção Voyages, relations et mémoires originaux pour servir a l'histoire de la découverte de l'Amerique, da editora Ternaux-Compans. Embora o prefácio do editor francês afirme ser esta a primeira versão francesa do famoso livro de Staden so o Brasil, J.C. Rodrigues fala de uma edição francesa em Amsterdã, de 1714, se, contudo, fornecer detalhes. Mesmo sendo esta a segunda tradução francesa, é também rara. Narra a odisséia vivida pelo autor durante nove meses como prisioneiro dos Tupinambás, fonte de consulta importante sobre o período inicial de nossa história. Staden descreve, além das experiências de seu cativeiro, suas viagens ao Brasil, desde os portos de origem. Preocupa-se em citar os nomes das pessoas, com quem lidou em diversas circunstâncias. é a primeira publicação sobre os índios brasileiros e, ainda hoje, na opinião de Borba de Moraes "constitui uma das mais valiosas fontes da etnologia em geral e da tupinologia especialmente".

NS方程数值模拟多学科问题-离散阵风响应(英文)

<正>BasedonNavier-Stokesequationsandstructuralandflightdynamicequationsofmotion,dynamicresponsesinverticaldiscretegustflowperturbationareinvestigatedforasupersonictransportmodel.Atightlycoupledmethodwasdevelopedbysubiterationsbetweenaerodynamicequationsanddynamicequationsofmotion.First,undertheassumptionofrigid-bodyandsinglefreedomofmotionintheverticalplunging,theresultsofdirect-couplingmethodarecomparedwiththeresultsofquasi-steadymodelmethod.Thengustresponsesfortheone-minus-cosinegustprofileareanalyzedwithtwo-freedomsofmotioninplungingandpitchingfortheairplaneconfigurationswithandwithout

NS方法数值预测跨音速气动颤振边界(英文)

本文通过耦合求解三维薄层Navier-Stokes方程与结构运动方程数值模拟了跨音速气动颤振现象。其中,流动控制方程的求解采用具有三阶精度的HLLEW(Harten-Lax-vanLeer-EinfeldtWada)迎风TVD空间离散格式和LU-SGS内迭代时间推进方法,同样的内迭代方法用于结构运动方程的求解。在每一步实时推进计算中,通过内迭代,使整个耦合计算的时间精度达到二阶。针对每一时间步的结构变形,发展了一种自适应网格变形方法,在中等结构变形的情况下,该方法能保证变形后的网格具有原网格的质量。为检验发展的跨音速气动颤振计算程序,对一标准气动弹性机翼的跨音速气动弹性边界进行了计算,获得了与实验一致的结果。另外,还详细研究了网格数、时间步长及内迭代步数对气动颤振计算的影响。

扩散抛物化(DP)NS方程组的意义及其在计算流体力学中的应用

本文首先讨论扩散抛物化(DP)NS方程组的早期研究工作:它的提出、数学性质、意义和在CFD中的应用,然后讨论扩散抛物化理论的一些新发展。这些新发展是对NS方程组数值计算进行物理分析的基础上得到的,其中包括NS方程组差分计算时,粘性剪切流对网格间距和格式精度的要求;粘性项只保留剪切粘性项的广义扩散抛物化(GDP)NS方程组,它的性质和应用。由于高Re数流动在NS方程组的差分计算中,网格Re数彼此相差悬殊的特点,产生了计算离散单元守恒方程组的新的算法思路,即离散流体力学(DFD)算法。在DFD算法中需要同时计算三种不同的守恒方程组(Euler,DPNS和NS方程组)。本文讨论了DFD格式的构造、它的优点和应用。并以超声速绕前后台阶流动为算例,来说明GDPNS方程组的用处和DFD算法的优点。DPNS方程组、GDPNS方程组、DFD算法是高智提出的,对这些问题他和合作者从

Translation, literature and nation: the Xeneración Nós and the appropriation of Joyce's texts

Santamaría, José Miguel; Pajares, Eterio; Olsen, Vickie; Merino, Raquel; Eguíluz, Federico (eds.)

Navier-Stokes(NS)方程组差分计算中的物理和网格尺度效应及NS方程组的简化

对于高Re数流动计算,在通常二阶精度NS差分格式和网格数条件下,存在某些粘性项落入修正微分方程截断误差项的问题。这类NS方程组计算实际是计算某种简化NS方程组,而且重复计算误差物理粘性项既浪费机时和内存,误差积累又会对数值解产生不可预测的影响。避免上述缺陷的办法一个是提高NS差分格式的精度,另一个是丢掉可能落入截断误差项的物理粘性项,把NS方程组简化为广义NS方程组。广义NS计算避免了误差物理粘性项误差积累对数值解的不可知影响,又可节省内存和机时,对高Re数流体工程计算很有好处。利用广义NS方程组计算超声速绕前向和后向台阶流动的结果表明:广义NS方程组与NS方程组的数值结果很好相符。

Les Portugais d'Amérique : souvenirs historiques de la guerre du Brésil en 1635 : contenant un tableau intéressant des moeurs et usages des tribus sauvages, des détails instructifs sur la situation des colons dans cette partie du nouveau-monde : ouvrage destiné a la jeunesse

Illustré de 12 dessins impremés en 2 couleurs

Exame da compatibilidade e adequação orçamentária e financeira dos Projetos de Lei nºs 7.917, de 2014, e 7.918, de 2014 : Subsídios da Magistratura e Ministério Público

Trabalho resultado do Trabalho nº 724/2014, do Deputado Nelson Marchezan Júnior que solicitou a esta Consultoria de Orçamento e Fiscalização Financeira Nota Técnica sobre a adequação orçamentária e financeira dos Projetos de Lei nºs 7.918 e 7.917, de 2014, que reajustam os subsídios do Procurador-Geral da República e dos ministros do Supremo Tribunal Federal, respectivamente.