24,399 research outputs found

    Controlling the sense of molecular rotation

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    We introduce a new scheme for controlling the sense of molecular rotation. By varying the polarization and the delay between two ultrashort laser pulses, we induce unidirectional molecular rotation, thereby forcing the molecules to rotate clockwise/counterclockwise under field-free conditions. We show that unidirectionally rotating molecules are confined to the plane defined by the two polarization vectors of the pulses, which leads to a permanent anisotropy in the molecular angular distribution. The latter may be useful for controlling collisional cross-sections and optical and kinetic processes in molecular gases. We discuss the application of this control scheme to individual components within a molecular mixture in a selective manner.Comment: 21 pages, 10 figures, Submitted to the New Journal of Physics for the "coherent control" special issu

    Dynamical coupled-channels: the key to understanding resonances

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    Recent developments on a dynamical coupled-channels model of hadronic and electromagnetic production of nucleon resonances are summarized.Comment: Invited Plenary talk at the 20th European Conference on Few-Body Problems in Physics (EFB20), September 10-14 2007, Pisa, Italy. To appear in the proceedings in Few-Body System

    Role of various physical and chemical techniques for hollow fibre forward osmosis membrane cleaning

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    © 2015 Balaban Desalination Publications. All rights reserved. Fouling is an inevitable phenomenon with most of the water treatment systems. Similar to RO, NF and other membrane-based systems, fouling also seriously affects the performance of low-cost forward-osmosis (FO) systems and disturbs the overall efficiency of these systems, and various cleaning practices have been evaluated to restore their designed performances. This study evaluates the performance of various physical and chemical cleaning techniques for hollow fibre forward-osmosis (HFFO) membrane. HFFO membrane was subjected to various fouling conditions using different brackish groundwater qualities and model organic foulants such as alginate, humic acid and bovine serum albumin. Results indicated that physical cleaning affects differently the flux restoration according to the type of foulants (i.e. inorganic or organic) and the crossflow rates play an important role in membrane cleaning in both membrane orientation. The higher cross flow Re values at any particular area seem important for the cleaning. With hydraulic flushing, the flux performances of HFFO were recovered fully when operated in AL-FS orientation, as high shear force helps to detach all scaling layers from the surface; however, the lower shear force did not fully restore the flux for the FS membrane in AL-DS orientation. Chemical cleaning was planned for the fouled HFFO membrane, and HCl and NaOH were used in various combination sequences. It was found that HCl did not clean the membrane used for AL-DS orientation for combined fouling. HCl cleaning (at pH 2) was found to be more effective for removing inorganic scale, whereas NaOH cleaning (at pH 11) for a similar period successfully restored the flux for all the membranes used for FS with inorganic and/or organic foulants. ethylenediamine tetra acetic acid (EDTA) was also evaluated for its cleaning performances and it was found that compared to NaOH, EDTA cleaning (1 mM concentration at pH 11) showed superior results in terms of membrane cleaning, as it helped to successfully restore the membrane flux in a very short time

    Off-Street Vehicular Fog for Catering Applications in 5G/B5G: A Trust-based Task Mapping Solution and Open Research Issues

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    One of the key enablers in serving the applications requiring stringent latency in 5G networks is fog computing as it is situated closer to the end users. With the technological advancement of vehicles’ on-board units, their computing capabilities are becoming robust, and considering the underutilization of the off-street vehicles, we envision that the off-street vehicles can be an enormously useful computational source for the fog computing. Additionally, clustering the vehicles would be advantageous in order to improve the service availability. As the vehicles become highly connected, trust is needed especially in distributed environments. However, vehicles are made from different manufacturers, and have different platforms, security mechanisms, and varying parking duration. These lead to the unpredictable behavior of the vehicles where quantifying trust value of vehicles would be difficult. A trust-based solution is necessary for task mapping as a task has a set of properties including expected time to complete, and trust requirements that need to be met. However, the existing metrics used for trust evaluation in the vehicular fog computing such as velocity and direction are not applicable in the off-street vehicle fog environments. In this paper, we propose a framework for quantifying the trust value of off-street vehicle fog computing facilities in 5G networks and forming logical clusters of vehicles based on the trust values. This allows tasks to be shared with multiple vehicles in the same cluster that meets the tasks’ trust requirements. Further, we propose a novel task mapping algorithm to increase the vehicle resource utilization and meet the desired trust requirements while maintaining imposed latency requirements of 5G applications. Results obtained using iFogSim simulator demonstrate that the proposed solution increases vehicle resource utilization and reduces task drop noticeably. This paper presents open research issues pertaining to the study to lead..

    Impact of diagnostic misclassification on estimation of genetic correlations using genome-wide genotypes

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    Disorders that share genetic risk factors often are placed in closely related diagnostic categories and treated similarly. Until recently, evidence for shared genetic etiology derived from classical research strategies – coaggregation in family and twin studies. Accumulating sufficient numbers of families was often problematic. However, in the era of genome-wide genotyping, we can now directly estimate the degree of sharing of genetic risk factors between disorders. This strategy is practical even for very rare disorders, where it is infeasible to ascertain informative families. Importantly, the estimates of genetic correlations from genome-wide genotypes are derived using such distant relatives that contamination by shared environmental factors seems unlikely. However, any method that seeks to quantify the shared etiology of disorders assumes they can be distinguished diagnostically from one another without error. Here we investigate the impact of misdiagnosis on estimates of genetic correlation both from traditional family data and from genome-wide genotypes of case–control samples from unrelated individuals. Our analyses show similar results for levels of misdiagnosis in both types of data. In both scenarios, genetic variances and heritabilities tend to be slightly underestimated but genetic correlations are overestimated, sometimes substantially so. For example, two genetically distinct but equally heritable disorders each with prevalence 1%, can generate false-positive estimates of genetic correlations of >0.2 in the presence of 10% reciprocal misdiagnosis. Strategies for minimizing the effects of misdiagnosis in cross-disorder genetic studies are discussed

    Biological potential of polyethylene glycol (Peg)-functionalized graphene quantum dots in in vitro neural stem/progenitor cells

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    Stem cell therapy is one of the novel and prospective fields. The ability of stem cells to differentiate into different lineages makes them attractive candidates for several therapies. It is essential to understand the cell fate, distribution, and function of transplanted cells in the local microenvironment before their applications. Therefore, it is necessary to develop an accurate and reliable labeling method of stem cells for imaging techniques to track their translocation after transplantation. The graphitic quantum dots (GQDs) are selected among various stem cell labeling and tracking strategies which have high photoluminescence ability, photostability, relatively low cytotoxicity, tunable surface functional groups, and delivering capacity. Since GQDs interact easily with the cell and interfere with cell behavior through surface functional groups, an appropriate surface modification needs to be considered to get close to the ideal labeling nanoprobes. In this study, polyethylene glycol (PEG) is used to improve biocompatibility while simultaneously maintaining the photoluminescent potentials of GQDs. The biochemically inert PEG successfully covered the surface of GQDs. The PEG-GQDs composites show adequate bioimaging capabilities when internalized into neural stem/progenitor cells (NSPCs). Furthermore, the bio-inertness of the PEG-GQDs is confirmed. Herein, we introduce the PEG-GQDs as a valuable tool for stem cell labeling and tracking for biomedical therapies in the field of neural regeneration

    Late widespread skeletal metastases from myxoid liposarcoma detected by MRI only

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    Background Myxoid liposarcoma is the second most commonly occurring sub-type of liposarcomas. In contrast to other soft tissue sarcomas, it is known to have a tendency to spread toward extrapulmonary sites, such as soft tissues, retroperitoneum, and the peritoneal surface. Bony spread, however, is not as common. Case presentation We report an unusual case of diffuse skeletal metastases from myxoid liposarcoma occurring 13 years after treatment of the primary tumour in the left lower limb. The skeletal spread of the disease was demonstrated on MRI only after other imaging modalities (plain radiography, CT and TC99 bone scans) had failed to detect these metastases. Conclusion MRI is an extremely sensitive and specific screening tool in the detection of skeletal involvement in these types of sarcomas, and therefore, should be a part of the staging proces

    Signal peptide peptidases and gamma-secretase: Cousins of the same protease family?

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    Signal peptide peptidase (SPIP) is an unusual aspartyl protease, which mediates clearance of signal peptides by proteolysis within the endoplasmic reticulum (ER). Like presenilins, which provide the proteolytically active subunit of the,gamma-secretase complex, SPP contains a conserved GxGD motif in its C-terminal domain which is critical for its activity. While SPIP is known to be an aspartyl protease of the GxGD type, several presenilin homologues/SPP-like proteins (PSHs/ SPPL) of unknown function have been identified by database searches. In contrast to SPP and SPPL3, which are both restricted to the endoplasmic reticulum, SPPL2b is targeted through the secretory pathway to endosomes/lysosomes. As suggested by the differential subcellular localization of SPPL2b and SPPL3 distinct phenotypes were found upon antisense gripNA-mediated knockdown in zebrafish. spp and sppl3 knockdowns in zebrafish result in cell death within the central nervous system, whereas reduction of sppl2b expression causes erythrocyte accumulation in an enlarged caudal vein. Moreover, expression of D/A mutants of the putative C-terminal active sites of spp, sppl2, and spp13 produced phenocopies of the respective knockdown phenotypes. These data suggest that all investigated PSHs/SPPLs are members of the novel family of GxGD aspartyl proteases. More recently, it was shown that SPPL2b utilizes multiple intramembrane cleavages to liberate the TNF(x intracellular domain into the cytosol and to release the C-terminal counterpart into the lumen. These findings suggest common principles of intramembrane proteolysis by GxGD type aspartyl proteases. In this article,we will review the similarities of SPPs and gamma-secretase based on recent findings by us and others

    Software-defined networking for ubiquitous healthcare service delivery

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    The growth of the mobile, portable devices and the server-to-server communication through cloud computing increase the network traffic. The dependence of the ubiquitous healthcare service delivery on the network connectivity creates failures that may interrupt or delay the treatment plan with adverse effects in patients’ quality of life even leading to mortality. In the present work, we propose the incorporation of Software Defined Networking (SDN) features in the healthcare domain in order to provide the appropriate bandwidth and guarantee the accurate real time medical data transmission independently of the connectivity of the ISP provider. The SDN controller monitors the network traffic and specifies how traffic should be routed providing load balancing, lower delays and better performance. Finally, the proposed healthcare architecture addresses the SDN scalability challenge by incorporating the logically centralized control plane using multiple distributed controllers. A 2-tier hierarchical overlay is formed among SDN controllers following the principles of peer-to-peer networking
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