70 research outputs found

    DRS: Dynamic Resource Scheduling for Real-Time Analytics over Fast Streams

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    In a data stream management system (DSMS), users register continuous queries, and receive result updates as data arrive and expire. We focus on applications with real-time constraints, in which the user must receive each result update within a given period after the update occurs. To handle fast data, the DSMS is commonly placed on top of a cloud infrastructure. Because stream properties such as arrival rates can fluctuate unpredictably, cloud resources must be dynamically provisioned and scheduled accordingly to ensure real-time response. It is quite essential, for the existing systems or future developments, to possess the ability of scheduling resources dynamically according to the current workload, in order to avoid wasting resources, or failing in delivering correct results on time. Motivated by this, we propose DRS, a novel dynamic resource scheduler for cloud-based DSMSs. DRS overcomes three fundamental challenges: (a) how to model the relationship between the provisioned resources and query response time (b) where to best place resources; and (c) how to measure system load with minimal overhead. In particular, DRS includes an accurate performance model based on the theory of \emph{Jackson open queueing networks} and is capable of handling \emph{arbitrary} operator topologies, possibly with loops, splits and joins. Extensive experiments with real data confirm that DRS achieves real-time response with close to optimal resource consumption.Comment: This is the our latest version with certain modificatio

    Palatini Formalism of 5-Dimensional Kaluza-Klein Theory

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    The Einstein field equations can be derived in nn dimensions (n>2n>2) by the variations of the Palatini action. The Killing reduction of 5-dimensional Palatini action is studied on the assumption that pentads and Lorentz connections are preserved by the Killing vector field. A Palatini formalism of 4-dimensional action for gravity coupled to a vector field and a scalar field is obtained, which gives exactly the same fields equations in Kaluza-Klein theory.Comment: 10 page

    The Effects of Uygur Herb Hyssopus officinalis

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    It has been proved that Uygur herb Hyssopus offcinalis L. could affect the levels of some cytokines (such as IL-4, IL-6, IL-17, and IFN-γ) in asthmatic mice. By detection of the expressions of MMP-9 and TIMP-1 and the morphological changes, the aim of this research is to reveal the mechanism of Uygur herb Hyssopus offcinalis L. in the process of airway remodeling. It was observed that the expressions of MMP-9 and TIMP-1 increased, but the ratio of MMP-9/TIMP-1 decreased in airway remodeling group. However, the expression of both MMP-9 and TIMP-1 decreased after being treated with dexamethasone and Hyssopus offcinalis L., accompanied by the relieved pathological changes, including collagen deposition, mucus secretion, and smooth muscle proliferation. It is suggested that Uygur herb Hyssopus offcinalis L. could inhibit airway remodeling by correcting imbalance of MMP-9/TIMP-1 ratio

    Review of thermal management of catalytic converters to decrease engine emissions during cold start and warm up

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    Catalytic converters mitigate carbon monoxide, hydrocarbon, nitrogen oxides and particulate matter emissions from internal combustion engines, and allow meeting the increasingly stringent emission regulations. However, catalytic converters experience light-off issues during cold start and warm up. This paper reviews the literature on the thermal management of catalysts, which aims to significantly reduce the light-off time and emission concentrations through appropriate heating methods. In particular, methods based on the control of engine parameters are easily implementable, as they do not require extra heating devices. They present good performance in terms of catalyst light-off time reduction, but bring high fuel penalties, caused by the heat loss and unburnt fuel. Other thermal management methods, such as those based on burners, reformers and electrically heated catalysts, involve the installation of additional devices, but allow flexibility in the location and intensity of the heat injection, which can effectively reduce the heat loss in the tailpipe. Heat storage materials decrease catalyst light-off time, emission concentrations and fuel consumption, but they are not effective if the engine remains switched off for long periods of time. The main recommendation of this survey is that integrated and more advanced thermal management control strategies should be developed to reduce light-off time without significant energy penalty

    Genome-Wide Compensatory Changes Accompany Drug- Selected Mutations in the Plasmodium falciparum crt Gene

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    Mutations in PfCRT (Plasmodium falciparum chloroquine-resistant transporter), particularly the substitution at amino acid position 76, confer chloroquine (CQ) resistance in P. falciparum. Point mutations in the homolog of the mammalian multidrug resistance gene (pfmdr1) can also modulate the levels of CQ response. Moreover, parasites with the same pfcrt and pfmdr1 alleles exhibit a wide range of drug sensitivity, suggesting that additional genes contribute to levels of CQ resistance (CQR). Reemergence of CQ sensitive parasites after cessation of CQ use indicates that changes in PfCRT are deleterious to the parasite. Some CQR parasites, however, persist in the field and grow well in culture, which may reflect adaptive changes in the parasite genome to compensate for the mutations in PfCRT. Using three isogenic clones that have different drug resistance profiles corresponding to unique mutations in the pfcrt gene (106/1K76, 106/176I, and 106/76I-352K), we investigated changes in gene expression in these parasites grown with and without CQ. We also conducted hybridizations of genomic DNA to identify copy number (CN) changes in parasite genes. RNA transcript levels from 45 genes were significantly altered in one or both mutants relative to the parent line, 106/1K76. Most of the up-regulated genes are involved in invasion, cell growth and development, signal transduction, and transport activities. Of particular interest are genes encoding proteins involved in transport and/or regulation of cytoplasmic or compartmental pH such as the V-type H+ pumping pyrophosphatase 2 (PfVP2), Ca2+/H+ antiporter VCX1, a putative drug transporter and CN changes in pfmdr1. These changes may represent adaptations to altered functionality of PfCRT, a predicted member of drug/metabolite transporter superfamily found on the parasite food vacuole (FV) membrane. Further investigation of these genes may shed light on how the parasite compensates for functional changes accompanying drug resistance mutations in a gene coding for a membrane/drug transporter

    Nucleic acid nanostructure for delivery of CRISPR/Cas9‐based gene editing system

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    Abstract CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR‐associated protein 9)‐based gene editing system has aroused great interest in many research fields. However, the efficient and safe delivery of this gene editing system into the target tissues and cells remain a major challenge. During the past decades, nucleic acid nanostructures have been widely developed for drug delivery. In this perspective, we will introduce and discuss the recent progress in the design of multifunctional nucleic acid nanostructures, including RCA‐derived DNA, branched DNA, and hybrid DNA, for delivery of the CRISPR/Cas9‐based gene editing system. Furthermore, we prospect the challenges and future opportunities of nucleic acid nanotechnology in the delivery of gene editing systems

    MicroRNA miR-146a-5p inhibits the inflammatory response and injury of airway epithelial cells via targeting TNF receptor-associated factor 6

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    Bronchial asthma is a common respiratory disease, which is characterized by airway inflammation, remodeling and hyperresponsiveness. MicroRNAs (miRNAs), as reported, are implicated in the pathogenesis of many diseases, but how miRNAs-146a-5p (miR-146a-5p) works in asthma remains inconclusive. In this work, we proved that miR-146a-5p expression was inhibited in asthma patients’ plasma and platelet activating factor (PAF)-induced human small airway epithelial cells (HSAECs). MiR-146a-5p up-regulation ameliorated the inflammatory reaction and cell barrier damage of HSAECs induced by PAF, and inhibited the apoptosis; besides, miR-146a-5p down-regulation functioned oppositely. In addition, miR-146a-5p could target TNF receptor-associated factor 6 (TRAF6) and negatively regulate its expression. TRAF6 overexpression could counterract the impact of miR-146a-5p up-regulation on PAF-induced inflammation, cell barrier damage and apoptosis of HSAECs. Collectively, miR-146a-5p may protect airway epithelial cells and inhibit the pathogenesis of asthma via targeting TRAF6
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