1,501 research outputs found
Collaborative Uploading in Heterogeneous Networks: Optimal and Adaptive Strategies
Collaborative uploading describes a type of crowdsourcing scenario in
networked environments where a device utilizes multiple paths over neighboring
devices to upload content to a centralized processing entity such as a cloud
service. Intermediate devices may aggregate and preprocess this data stream.
Such scenarios arise in the composition and aggregation of information, e.g.,
from smartphones or sensors. We use a queuing theoretic description of the
collaborative uploading scenario, capturing the ability to split data into
chunks that are then transmitted over multiple paths, and finally merged at the
destination. We analyze replication and allocation strategies that control the
mapping of data to paths and provide closed-form expressions that pinpoint the
optimal strategy given a description of the paths' service distributions.
Finally, we provide an online path-aware adaptation of the allocation strategy
that uses statistical inference to sequentially minimize the expected waiting
time for the uploaded data. Numerical results show the effectiveness of the
adaptive approach compared to the proportional allocation and a variant of the
join-the-shortest-queue allocation, especially for bursty path conditions.Comment: 15 pages, 11 figures, extended version of a conference paper accepted
for publication in the Proceedings of the IEEE International Conference on
Computer Communications (INFOCOM), 201
Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes
Recent multi-photon ionization (MPI) experiments on uracil revealed a fragment ion at m/z 84 that was proposed as a potential marker for ring opening in the electronically excited neutral molecule. The present MPI measurements on deuterated uracil identify the fragment as C3H4N2O+ (uracil+ less CO), a plausible dissociative ionization product from the theoretically predicted open-ring isomer. Equivalent measurements on thymine do not reveal an analogous CO loss channel, suggesting greater stability of the excited DNA base. MPI and electron impact ionization experiments have been carried out on uracil-adenine clusters in order to better understand the radiation response of uracil within RNA. Evidence for C3H4N2O+ production from multi-photon-ionized uracil-adenine clusters is tentatively attributed to a significant population of π-stacked configurations in the neutral beam
Efficacy of erythropoietin-pretreated mesenchymal stem cells in murine burn wound healing: possible in vivo transdifferentiation into keratinocytes
Background: Stem cells have shown promising potential to treat burn wounds. Erythropoietin was capable of promoting in vitro transdifferentiation of mesenchymal stem cells (MSCs). The aim of the study was to investigate possible role of erythropoietin-pretreated mesenchymal stem cells (EPOa/MSCs) in burn wounds healing and to evaluate its in vivo differentiation into keratinocytes. Materials and methods: Forty rats were utilised in this study divided into four groups (n = 10 for each). Control group (I), burn group (II), burn + MSCs, group (III), burn + EPOa/MSCs. 1 × 106 cells were injected locally for each 1 cm2 of burn areas. Burn areas were followed-up morphologically. After 21 days of the experiment, the rats were euthanised, skin specimens were assessed biochemically, histologically and immunohistochemically. Results: EPOa/MSCs enhanced significantly (p < 0.05) burn wound vimentin gene expression and level of interleukin (IL)-10 while decreased IL-1 and COX2 as compared to the burn group. Histologically, EPOa/MSCs improved epithelialisation despite stem cells’ differentiation into keratinocytes was rarely detected by PKH26 red fluorescence. EPOa/MSCs promoted angiogenesis as detected by significant increase in VEGF and PDGF immunoexpression as compared to burn group. Conclusions: EPOa/MSCs may improve burn wound healing, probably through anti-inflammatory, immunomodulatory and angiogenic action. However, in vivo transdifferentiation into keratinocytes was rarely detected
On the Fidelity Distribution of Link-level Entanglements under Purification
Quantum entanglement is the key to quantum communications over considerable
distances. The first step for entanglement distribution among quantum
communication nodes is to generate link-level Einstein-Podolsky-Rosen (EPR)
pairs between adjacent communication nodes. EPR pairs may be continuously
generated and stored in a few quantum memories to be ready for utilization by
quantum applications. A major challenge is that qubits suffer from unavoidable
noise due to their interaction with the environment, which is called
decoherence. This decoherence results in the known exponential decay model of
the fidelity of the qubits with time, thus, limiting the lifetime of a qubit in
a quantum memory and the performance of quantum applications.
In this paper, we evaluate the fidelity of the stored EPR pairs under two
opposite dynamical and probabilistic phenomena, first, the aforementioned
decoherence and second purification, i.e. an operation to improve the fidelity
of an EPR pair at the expense of sacrificing another EPR pair. Instead of
applying the purification as soon as two EPR pairs are generated, we introduce
a Purification scheme Beyond the Generation time (PBG) of two EPR pairs. We
analytically show the probability distribution of the fidelity of stored
link-level EPR pairs in a system with two quantum memories at each node
allowing a maximum of two stored EPR pairs. In addition, we apply a PBG scheme
that purifies the two stored EPR pairs upon the generation of an additional
one. We finally provide numerical evaluations of the analytical approach and
show the fidelity-rate trade-off of the considered purification scheme
End-Fire Silicon Optical Phased Array with Half-Wavelength Spacing
We demonstrate a one-dimensional optical phased array on an integrated
silicon platform for operation at 1.55 microns. Light is emitted end-fire from
the chip edge where the waveguides are terminated. The innovative design and
high confinement afforded by the silicon waveguides enables lambda/2 spacing
(775-nm pitch) at the output. Steering is achieved by inducing a phase shift
between the waveguides via integrated thermo-optic heaters. The device forms a
beam with a FWHM angular width of 17 degrees, and we demonstrate beam steering
over a 64 degrees range
Cost-effectiveness of dedicated dietitians for hyperphosphatemia management among hemodialysis patients in Lebanon: Results from the nutrition education for management of osteodystrophy trial
Sunlight exposure is just one of the factors which influence Vitamin D status
© The Royal Society of Chemistry and Owner Societies. Studies on the determinants of vitamin D status have tended to concentrate on input-exposure to ultraviolet B radiation and the limited sources in food. Yet, vitamin D status, determined by circulating concentrations of 25-hydroxyvitamin D (25(OH)D), can vary quite markedly in groups of people with apparently similar inputs of vitamin D. There are small effects of polymorphisms in the genes for key proteins involved in vitamin D production and metabolism, including 7-dehydrocholesterol reductase, which converts 7-dehydrocholesterol, the precursor of vitamin D, to cholesterol, CYP2R1, the main 25-hydroxylase of vitamin D, GC, coding for the vitamin D binding protein which transports 25(OH)D and other metabolites in blood and CYP24A1, which 24-hydroxylates both 25(OH)D and the hormone, 1,25-dihydroxyvitamin D. 25(OH)D has a highly variable half-life in blood. There is evidence that the half-life of 25(OH)D is affected by calcium intake and some therapeutic agents. Fat tissue seems to serve as a sink for the parent vitamin D, which is released mainly when there are reductions in adiposity. Some evidence is presented to support the proposal that skeletal muscle provides a substantial site of sequestration of 25(OH)D, protecting this metabolite from degradation by the liver, which may help to explain why exercise, not just outdoors, is usually associated with better vitamin D status
U.V. spectra parameters to investigate the influences of intensifications of soybean with sorghum and maize on the physical properties of soybean seed oils
Effect of intradialytic-aerobic exercise on clinical outcomes of hemodialysis patients in the United Arab Emirates
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