101 research outputs found

    Chance constrained robust downlink beamforming in multicell networks

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    We introduce a downlink robust optimization approach that minimizes a combination of total transmit power by a multiple antenna base station (BS) within a cell and the resulting aggregate inter-cell interference (ICI) power on the users of the other cells. This optimization is constrained to assure that a set of signal-to-interference-plus-noise ratio (SINR) targets are met at user terminals with certain outage probabilities. The outages are due to the uncertainties that naturally emerge in the estimation of channel covariance matrices between a BS and its intra-cell local users as well as the other users of the other cells. We model these uncertainties using random matrices, analyze their statistical behaviour and formulate a tractable probabilistic approach to the design of optimal robust downlink beamforming vectors. The proposed approach reformulates the original intractable non-convex problem in a semidefinite programming (SDP) form with linear matrix inequality (LMI) constraints. The resulting SDP formulation is convex and numerically tractable under the standard rank relaxation. We compare the proposed chance-constrained approach against two different robust design schemes as well as the worst-case robustness. The simulation results confirm better power efficiency and higher resilience against channel uncertainties of the proposed approach in realistic scenarios

    Synthetic matrix enhances transplanted satellite cell engraftment in dystrophic and aged skeletal muscle with comorbid trauma

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    Muscle satellite cells (MuSCs) play a central role in muscle regeneration, but their quantity and function decline with comorbidity of trauma, aging, and muscle diseases. Although transplantation of MuSCs in traumatically injured muscle in the comorbid context of aging or pathology is a strategy to boost muscle regeneration, an effective cell delivery strategy in these contexts has not been developed. We engineered a synthetic hydrogel-based matrix with optimal mechanical, cell-adhesive, and protease-degradable properties that promotes MuSC survival, proliferation, and differentiation. Furthermore, we establish a biomaterial-mediated cell delivery strategy for treating muscle trauma, where intramuscular injections may not be applicable. Delivery of MuSCs in the engineered matrix significantly improved in vivo cell survival, proliferation, and engraftment in nonirradiated and immunocompetent muscles of aged and dystrophic mice compared to collagen gels and cell-only controls. This platform may be suitable for treating craniofacial and limb muscle trauma, as well as postoperative wounds of elderly and dystrophic patients.Research reported in this publication was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the NIH under award numbers R21AR072287 (to Y.C.J.) and R01AR062368 (to A.J.G.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. This work was also funded by the Parker H. Petit Institute for Bioengineering and Bioscience Seed Grant Program (to A.J.G. and Y.C.J.)

    Synthetic matrix enhances transplanted satellite cell engraftment in dystrophic and aged skeletal muscle with comorbid trauma

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    Muscle satellite cells (MuSCs) play a central role in muscle regeneration, but their quantity and function decline with comorbidity of trauma, aging, and muscle diseases. Although transplantation of MuSCs in traumatically injured muscle in the comorbid context of aging or pathology is a strategy to boost muscle regeneration, an effective cell delivery strategy in these contexts has not been developed. We engineered a synthetic hydrogel-based matrix with optimal mechanical, cell-adhesive, and protease-degradable properties that promotes MuSC survival, proliferation, and differentiation. Furthermore, we establish a biomaterial-mediated cell delivery strategy for treating muscle trauma, where intramuscular injections may not be applicable. Delivery of MuSCs in the engineered matrix significantly improved in vivo cell survival, proliferation, and engraftment in nonirradiated and immunocompetent muscles of aged and dystrophic mice compared to collagen gels and cell-only controls. This platform may be suitable for treating craniofacial and limb muscle trauma, as well as postoperative wounds of elderly and dystrophic patients.Research reported in this publication was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the NIH under award numbers R21AR072287 (to Y.C.J.) and R01AR062368 (to A.J.G.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. This work was also funded by the Parker H. Petit Institute for Bioengineering and Bioscience Seed Grant Program (to A.J.G. and Y.C.J.)

    In-hospital complications after invasive strategy for the management of Non STEMI: women fare as well as men

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    <p>Abstract</p> <p>Background</p> <p>To analyze the in-hospital complication rate in women suffering from non-ST elevation myocardial infarction treated with percutaneous coronary intervention (PCI) compared to men.</p> <p>Methods</p> <p>The files of 479 consecutive patients (133 women and 346 men) suffering from a Non STEMI (Non ST-segment elevation myocardial infarction) between the January 1<sup>st </sup>2006 and March 21<sup>st </sup>2009 were retrospectively analyzed with special attention to every single complication occurring during hospital stay. Data were analyzed using nonparametric tests and are reported as median unless otherwise specified. A p value < .05 was considered significant.</p> <p>Results</p> <p>As compared to men, women were significantly older (75.8 <it>vs</it>. 65.2 years; p < .005). All cardiovascular risk factors but tobacco and hypertension were similar between the groups: men were noticeably more often smoker (p < .0001) and women more hypertensive (p < .005). No difference was noticed for pre-hospital cardiovascular drug treatment. However women were slightly more severe at entry (more Killip class IV; p = .0023; higher GRACE score for in-hospital death - p = .008 and CRUSADE score for bleeding - p < .0001). All the patients underwent PCI of the infarct-related artery after 24 or 48 hrs post admission without sex-related difference either for timing of PCI or primary success rate. During hospitalization, 130 complications were recorded. Though the event rate was slightly higher in women (30% <it>vs</it>. 26% - p = NS), no single event was significantly gender related. The logistic regression identified age and CRP concentration as the only predictive variables in the whole group. After splitting for genders, these parameters were still predictive of events in men. In women however, CRP was the only one with a borderline p value.</p> <p>Conclusions</p> <p>Our study does not support any gender difference for in-hospital adverse events in patients treated invasively for an acute coronary syndrome without ST-segment elevation and elevated troponin.</p

    Psychoactive Pharmaceuticals Induce Fish Gene Expression Profiles Associated with Human Idiopathic Autism

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    Idiopathic autism, caused by genetic susceptibility interacting with unknown environmental triggers, has increased dramatically in the past 25 years. Identifying environmental triggers has been difficult due to poorly understood pathophysiology and subjective definitions of autism. The use of antidepressants by pregnant women has been associated with autism. These and other unmetabolized psychoactive pharmaceuticals (UPPs) have also been found in drinking water from surface sources, providing another possible exposure route and raising questions about human health consequences. Here, we examined gene expression patterns of fathead minnows treated with a mixture of three psychoactive pharmaceuticals (fluoxetine, venlafaxine & carbamazepine) in dosages intended to be similar to the highest observed conservative estimates of environmental concentrations. We conducted microarray experiments examining brain tissue of fish exposed to individual pharmaceuticals and a mixture of all three. We used gene-class analysis to test for enrichment of gene sets involved with ten human neurological disorders. Only sets associated with idiopathic autism were unambiguously enriched. We found that UPPs induce autism-like gene expression patterns in fish. Our findings suggest a new potential trigger for idiopathic autism in genetically susceptible individuals involving an overlooked source of environmental contamination

    Robust and power efficient interference management in downlink multi-cell networks

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    In this paper, we focus on robust design of downlink beamforming vectors for multiple antenna base stations (BSs) in a multi-cell interference network. We formulate a robust optimization problem where an individual BS within a cell designs its beamforming vectors to minimize a combination of its sum-power, used for assuring a desired quality of service at its local users, and its aggregate induced interference on the users of the other cells, to balance inter-cell interference across the multiple cells. The proposed robust formulation uses spherical uncertainty sets to model imperfections in the second-order statistical channel knowledge between the BS and the users. To maintain tractability of the robust solutions, we derive an equivalent semidefinite programming (SDP) formulation that is convex under standard rank relaxation. The numerical results confirm the effectiveness of the proposed algorithm under various sizes of uncertainty set and the fact that the attained robust solutions always satisfy the rank constraint
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