Convexity properties of loss and overflow functions

We show that the fluid loss ratio in a fluid queue with finite buffer $b$ and constant link capacity $c$ is always a jointly convex function of $b$ and $c$. This generalizes prior work [6] which shows convexity of the $(b,c)$ trade-off for large number of i.i.d. multiplexed sources, using the large deviations rate function as approximation for fluid loss. Our approach also leads to a simpler proof of the prior result, and provides a stronger basis for optimal measurement-based control of resource allocation in shared resource systems

Spontaneous Resonances and the Coherent States of the Queuing Networks

We present an example of a highly connected closed network of servers, where the time correlations do not go to zero in the infinite volume limit. This phenomenon is similar to the continuous symmetry breaking at low temperatures in statistical mechanics. The role of the inverse temperature is played by the average load.Comment: 3 figures added, small correction

Functional responses of methanogenic archaea to syntrophic growth.

Methanococcus maripaludis grown syntrophically with Desulfovibrio vulgaris was compared with M. maripaludis monocultures grown under hydrogen limitation using transcriptional, proteomic and metabolite analyses. These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis. Compared with growth in monoculture under hydrogen limitation, the response of paralogous genes, such as those coding for hydrogenases, often diverged, with transcripts of one variant increasing in relative abundance, whereas the other was little changed or significantly decreased in abundance. A common theme was an apparent increase in transcripts for functions using H(2) directly as reductant, versus those using the reduced deazaflavin (coenzyme F(420)). The greater importance of direct reduction by H(2) was supported by improved syntrophic growth of a deletion mutant in an F(420)-dependent dehydrogenase of M. maripaludis. These data suggest that paralogous genes enable the methanogen to adapt to changing substrate availability, sustaining it under environmental conditions that are often near the thermodynamic threshold for growth. Additionally, the discovery of interspecies alanine transfer adds another metabolic dimension to this environmentally relevant mutualism

Models of memory interference in multiprocessors

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A stochastic network with mobile users in heavy traffic

We consider a stochastic network with mobile users in a heavy-traffic regime. We derive the scaling limit of the multi-dimensional queue length process and prove a form of spatial state space collapse. The proof exploits a recent result by Lambert and Simatos which provides a general principle to establish scaling limits of regenerative processes based on the convergence of their excursions. We also prove weak convergence of the sequences of stationary joint queue length distributions and stationary sojourn times.Comment: Final version accepted for publication in Queueing Systems, Theory and Application

Chemiluminescence activity of neutrophil granulocytes under the influence of magnetic nanoparticles of ferrihydrite (<i>in vitro</i>)

The article presents the results of studying and evaluating the impact of magnetic nanoparticles of ferrihydrite on neutrophil granulocytes in human blood (in vitro) in order to determine their bio compatibility and eco toxicity. The subject soft here search were blood neutrophil granulocytes of 29 conditionally-healthy donors of blood, as well as magnetic nanoparticles of ferrihydrite (NP), the preparation dose in minimum concentration reached 25 mg, in maximum concentration it reached 50 mg per 106 cells/ml. We implemented the sol of magnetic NP, obtained by biogenic synthesis in International Scientific Centre for Studying Extreme States of an Organism. Functional activity of blood neutrophil granulocytes has been determined by luminol-dependent chemiluminescence. Magnetic NP were introduced into pilot samples straight before chemiluminescent analysis, and also after the incubation with in 30 minutes under 37 °С entigrade. As a result of thee stimation of the early response of neutrophil granulocytes to the influence of minimum concentration of magnetic NP in vitro we found statistically true decrease of the intensity (1.6 times), the area under the curve (2.1 times) in zymosan-induced chemiluminescent response, the activation index (2.3 times). When evaluating the late response of neutrophil granulocytes to the influence of maximum concentration of magnetic NP in vitro we have found statistically true lowering of the time of reaching the peak (10 times) of spontaneous chemiluminescence. More over we marked consider able lowering of maximum intensity 6 times and the reduction of the area under the curve of zymosan-induced chemiluminescence 5.6 times under the influence of magnetic NP under the lowering of activation index 3.7 times. The authors determined that magnetic NP were intensively decreasing the functional activity of neutrophil granulocytes. The intensity of the impact is higher under the preliminary incubation of the cells with magnetic NP. At the same time, short effect of magnetic NP to neutrophil granulocytes can be a modulating one and depends on the initial level of cell reactivity. We revealed that magnetic NP influence concerns only activated cells

Metabolic modeling of a mutualistic microbial community

The rate of production of methane in many environments depends upon mutualistic interactions between sulfate-reducing bacteria and methanogens. To enhance our understanding of these relationships, we took advantage of the fully sequenced genomes of Desulfovibrio vulgaris and Methanococcus maripaludis to produce and analyze the first multispecies stoichiometric metabolic model. Model results were compared to data on growth of the co-culture on lactate in the absence of sulfate. The model accurately predicted several ecologically relevant characteristics, including the flux of metabolites and the ratio of D. vulgaris to M. maripaludis cells during growth. In addition, the model and our data suggested that it was possible to eliminate formate as an interspecies electron shuttle, but hydrogen transfer was essential for syntrophic growth. Our work demonstrated that reconstructed metabolic networks and stoichiometric models can serve not only to predict metabolic fluxes and growth phenotypes of single organisms, but also to capture growth parameters and community composition of simple bacterial communities

Mechanism for microbial population collapse in a fluctuating resource environment.

Managing trade-offs through gene regulation is believed to confer resilience to a microbial community in a fluctuating resource environment. To investigate this hypothesis, we imposed a fluctuating environment that required the sulfate-reduce

Genome-wide histone acetylation data improve prediction of mammalian transcription factor binding sites

Motivation: Histone acetylation (HAc) is associated with open chromatin, and HAc has been shown to facilitate transcription factor (TF) binding in mammalian cells. In the innate immune system context, epigenetic studies strongly implicate HAc in the transcriptional response of activated macrophages. We hypothesized that using data from large-scale sequencing of a HAc chromatin immunoprecipitation assay (ChIP-Seq) would improve the performance of computational prediction of binding locations of TFs mediating the response to a signaling event, namely, macrophage activation

Neurological manifestation (headache and ischemic stroke) is the onset of the atypical hemolythic uremic syndrome

Atypical hemolytic uremic syndrome is an orphan disease with a rare (10 % of cases) involvement in the pathological process of the central nervous system. The following symptoms are impaired consciousness, convulsions, strokes, transient ischemic attacks and headache. Presented by the observation of the patient, which had the neurological symptoms at the onset of the disease.Атипичный гемолитико-уремический синдром является орфанным заболеванием с редким (в 10% случаев) вовлечением в патологический процесс центральной нервной системы. Возможны следующие проявления: нарушение сознания, судороги, острые наррения мозгового кровообращения, транзиторные ишемические атаки, головная боль. Представлено клиническое наблюдение пациентки, у которой в дебюте заболевания преобладала неврологическая симптоматика