2,994 research outputs found
Coding packets over reordering channels
We define the “reordering channel” which approximates
packet communication over multipath networks. We consider
deterministic packet arrivals with finite horizon decoding
of individual packets and analyze the error probability for a two
stage coding scheme
Coding packets over reordering channels
We define the “reordering channel” which approximates
packet communication over multipath networks. We consider
deterministic packet arrivals with finite horizon decoding
of individual packets and analyze the error probability for a two
stage coding scheme
Transition zone in constant pressure converging flows
The effect of lateral streamline convergence alone on the transitional flow characteristics has been studied towards modelling the transition zone. Apart from a thicker boundary layer, the transitional flow characteristics are found to be similar to those in two-dimensional constant pressure flows. The transition zone has been modeled using the linear-combination model for two dimensional flows
Glimmers: Resolving the Privacy/Trust Quagmire
Many successful services rely on trustworthy contributions from users. To
establish that trust, such services often require access to privacy-sensitive
information from users, thus creating a conflict between privacy and trust.
Although it is likely impractical to expect both absolute privacy and
trustworthiness at the same time, we argue that the current state of things,
where individual privacy is usually sacrificed at the altar of trustworthy
services, can be improved with a pragmatic , which allows
services to validate user contributions in a trustworthy way without forfeiting
user privacy. We describe how trustworthy hardware such as Intel's SGX can be
used client-side -- in contrast to much recent work exploring SGX in cloud
services -- to realize the Glimmer architecture, and demonstrate how this
realization is able to resolve the tension between privacy and trust in a
variety of cases
Cytochrome cM decreases photosynthesis under photomixotrophy in Synechocystis sp. PCC 6803
Photomixotrophy is a metabolic state that enables photosynthetic microorganisms to simultaneously perform photosynthesis and metabolism of imported organic carbon substrates. This process is complicated in cyanobacteria, since many, including Synechocystis sp. PCC 6803, conduct photosynthesis and respiration in an interlinked thylakoid membrane electron transport chain. Under photomixotrophy, the cell must therefore tightly regulate electron fluxes from photosynthetic and respiratory complexes. In this study, we demonstrate, via characterization of photosynthetic apparatus and the proteome, that photomixotrophic growth results in a gradual inhibition of QA- reoxidation in wild-type Synechocystis, which largely decreases photosynthesis over 3 d of growth. This process is circumvented by deleting the gene encoding cytochrome cM (CytM), a cryptic c-type heme protein widespread in cyanobacteria. The ΔCytM strain maintained active photosynthesis over the 3-d period, demonstrated by high photosynthetic O2 and CO2 fluxes and effective yields of PSI and PSII. Overall, this resulted in a higher growth rate compared to that of the wild type, which was maintained by accumulation of proteins involved in phosphate and metal uptake, and cofactor biosynthetic enzymes. While the exact role of CytM has not been determined, a mutant deficient in the thylakoid-localized respiratory terminal oxidases and CytM (ΔCox/Cyd/CytM) displayed a phenotype similar to that of ΔCytM under photomixotrophy. This, in combination with other physiological data, and in contrast to a previous hypothesis, suggests that CytM does not transfer electrons to these complexes. In summary, our data suggest that CytM may have a regulatory role in photomixotrophy by modulating the photosynthetic capacity of cells
Early removal versus expectant management of central venous catheters in neonates with bloodstream infection
BACKGROUND: Uncertainty exists regarding the management of newborn infants with a bloodstream infection and a central venous catheter in place. The central venous catheter may act as a nidus for infecting organisms and observational studies have suggested that early removal of the catheter is associated with a lower incidence of persistent or complicated infection. However, since central venous catheters provide secure vascular access to deliver nutrition and medications, the possible harms of early removal versus expectant management also need to be considered. OBJECTIVES: To determine the effect of early removal versus expectant management of central venous catheters on morbidity and mortality in newborn infants with bloodstream infections. SEARCH METHODS: We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 11), MEDLINE (1966 to October 2015), EMBASE (1980 to October 2015), CINAHL (1982 to October 2015), conference proceedings and previous reviews. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials that compared early removal versus expectant management of central venous catheters in neonates with bloodstream infections. DATA COLLECTION AND ANALYSIS: We used the standard methods of the Cochrane Neonatal Review Group. MAIN RESULTS: We did not identify any eligible randomised controlled trials. AUTHORS' CONCLUSIONS: There are no trial data to guide practice regarding early removal versus expectant management of central venous catheters in newborn infants with bloodstream infections. A simple and pragmatic randomised controlled trial is needed to resolve the uncertainty about optimal management in this common and important clinical scenario
Spot propagation characteristics in laterally strained boundary layers
Owing to the importance of the spot propagation characteristics in transition zone modeling, the effect of lateral streamline convergence alone on the spot propagation characteristics has been studied. It is found that for the extent of lateral straining introduced here, the two-dimensional spot propagation characteristics are unaffected
Sympathetic inhibition of accommodation after sustained nearwork in subjects with myopia and emmetropia
PURPOSE. The purposes of the present study were to assess the effect of a sympathetic inhibitory pharmacologic agent, timolol maleate, on the magnitude of nearwork-induced transient myopia (NITM) and its decay in different refractive groups for an extended near task duration and to determine the proportion of the young adult population manifesting effective sympathetic access under naturalistic closed-loop viewing conditions. METHODS. Ten subjects with emmetropia and 10 with myopia were tested. They read binocularly for 1 hour at a distance of 35 to 40 cm. NITM was calculated as the difference in distance refractive state after task as compared with before task immediately after reading. All subjects received timolol maleate to block the sympathetic nervous system and betaxolol as a control agent in independent test sessions separated by at least 3 days. Forty minutes after drug instillation, the NITM measurement procedure was repeated. RESULTS. Initial NITM magnitude was larger in subjects with myopia than in subjects with emmetropia before and after timolol instillation. Furthermore, NITM magnitude in subjects with sympathetic access was increased after timolol instillation. In contrast, with the control agent betaxolol, there was no increase. NITM decay duration to baseline was increased after timolol instillation in the subjects with myopia only. Only 15% of the subjects (n = 3 subjects with myopia) demonstrated effective and significant access to sympathetic facility. CONCLUSIONS. Subjects with myopia demonstrated an increase in decay duration with timolol, thus suggesting impaired sympathetic inhibition of accommodation. This may be a precursor for myopia progression in some persons
Every Elementary Graph is Chromatic Choosable
Elementary graphs are graphs whose edges can be colored using two colors in
such a way that the edges in any induced get distinct colors. They
constitute a subclass of the class of claw-free perfect graphs. In this paper,
we show that for any elementary graph, its list chromatic number and chromatic
number are equal
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