355 research outputs found

    Circularly Polarized Aperture Coupled Microstrip Antenna with Resonant Slots and a Screen

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    A broadband circularly polarized (CP) Aperture Coupled Microstrip Antenna (ACMSA) is described herein. In order to decrease the back radiation of the antenna due to resonant coupling slots (a cross-slot) in the ground plane, a three-layer structure with a screen is proposed. As a result, the back radiation of the antenna is reduced by more than 12 dB and its gain is increased by about 1.3 dB compared to the conventional two-layer ACMSA with nonresonant coupling slots. The antenna is designed to operate within the Ku-band. Keeping its simple and compact construction and high mechanical characteristics it can be used as an element of CP microstrip antenna arrays with various applications in the contemporary communication systems. A comparison with two similar CP antennas with resonant slots, a two-layer ACMSA and a three-layer ACMSA with a patch reflector is accomplished

    A computationally efficient symmetric diagonally dominant matrix projection-based Gaussian process approach

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    Although kernel approximation methods have been widely applied to mitigate the O(n3) cost of the n × n kernel matrix inverse in Gaussian process methods, they still face computational challenges. The ‘residual’ matrix between the covariance and the approximating component is often discarded as it prevents the computational cost reduction. In this paper, we propose a computationally efficient Gaussian process approach that achieves better computational efficiency, O(mn2), compared with standard Gaussian process methods, when using m n data. The proposed approach incorporates the ‘residual’ matrix in its symmetric diagonally dominant form which can be further approximated by the Neumann series. We have validated and compared the approach with full Gaussian process approaches and kernel approximation based Gaussian process variants, both on synthetic and real air quality data

    A pilot study of an integrated mental health, social and medical model for diabetes care in an inner‐city setting: three dimensions for diabetes (3DFD)

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    Aims We examined the effectiveness of a service innovation, Three Dimensions for Diabetes (3DFD), that consisted of a referral to an integrated mental health, social care and diabetes treatment model, compared with usual care in improving biomedical and health economic outcomes. Methods Using a non‐randomized control design, the 3DFD model was offered in two inner‐city boroughs in London, UK, where diabetes health professionals could refer adult residents with diabetes, suboptimal glycaemic control [HbA1c ≥ 75 mmol/mol (≥ 9.0%)] and mental health and/or social problems. In the usual care group, there was no referral pathway and anonymized data on individuals with HbA1c ≥ 75 mmol/mol (≥ 9.0%) were collected from primary care records. Change in HbA1c from baseline to 12 months was the primary outcome, and change in healthcare costs and biomedical variables were secondary outcomes. Results 3DFD participants had worse glycaemic control and higher healthcare costs than control participants at baseline. 3DFD participants had greater improvement in glycaemic control compared with control participants [−14 mmol/mol (−1.3%) vs. −6 mmol/mol (−0.6%) respectively, P < 0.001], adjusted for confounding. Total follow‐up healthcare costs remained higher in the 3DFD group compared with the control group (mean difference £1715, 95% confidence intervals 591 to 2811), adjusted for confounding. The incremental cost‐effectiveness ratio was £398 per mmol/mol unit decrease in HbA1c, indicating the 3DFD intervention was more effective and costed more than usual care. Conclusions A biomedical, psychological and social criteria‐based referral system for identifying and managing high‐cost and high‐risk individuals with poor glycaemic control can lead to improved health in all three dimensions

    Status Update and Interim Results from the Asymptomatic Carotid Surgery Trial-2 (ACST-2)

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    Objectives: ACST-2 is currently the largest trial ever conducted to compare carotid artery stenting (CAS) with carotid endarterectomy (CEA) in patients with severe asymptomatic carotid stenosis requiring revascularization. Methods: Patients are entered into ACST-2 when revascularization is felt to be clearly indicated, when CEA and CAS are both possible, but where there is substantial uncertainty as to which is most appropriate. Trial surgeons and interventionalists are expected to use their usual techniques and CE-approved devices. We report baseline characteristics and blinded combined interim results for 30-day mortality and major morbidity for 986 patients in the ongoing trial up to September 2012. Results: A total of 986 patients (687 men, 299 women), mean age 68.7 years (SD ± 8.1) were randomized equally to CEA or CAS. Most (96%) had ipsilateral stenosis of 70-99% (median 80%) with contralateral stenoses of 50-99% in 30% and contralateral occlusion in 8%. Patients were on appropriate medical treatment. For 691 patients undergoing intervention with at least 1-month follow-up and Rankin scoring at 6 months for any stroke, the overall serious cardiovascular event rate of periprocedural (within 30 days) disabling stroke, fatal myocardial infarction, and death at 30 days was 1.0%. Conclusions: Early ACST-2 results suggest contemporary carotid intervention for asymptomatic stenosis has a low risk of serious morbidity and mortality, on par with other recent trials. The trial continues to recruit, to monitor periprocedural events and all types of stroke, aiming to randomize up to 5,000 patients to determine any differential outcomes between interventions. Clinical trial: ISRCTN21144362. © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved

    A Novel Role for the SMG-1 Kinase in Lifespan and Oxidative Stress Resistance in Caenorhabditis elegans

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    The PTEN tumour suppressor encodes a phosphatase, and its daf-18 orthologue in Caenorhabditis elegans negatively regulates the insulin/IGF-1 DAF-2 receptor pathway that influences lifespan in worms and other species. In order to identify new DAF-18 regulated pathways involved in aging, we initiated a candidate RNAi feeding screen for clones that lengthen lifespan. Here, we report that smg-1 inactivation increases average lifespan in a daf-18 dependent manner. Genetic analysis is consistent with SMG-1 acting at least in part in parallel to the canonical DAF-2 receptor pathway, but converging on the transcription factor DAF-16/FOXO. SMG-1 is a serine-threonine kinase which plays a conserved role in nonsense-mediated mRNA decay (NMD) in worms and mammals. In addition, human SMG-1 has also been implicated in the p53-mediated response to genotoxic stress. The effect of smg-1 inactivation on lifespan appears to be unrelated to its NMD function, but requires the p53 tumour suppressor orthologue cep-1. Furthermore, smg-1 inactivation confers a resistance to oxidative stress in a daf-18-, daf-16- and cep-1-dependent manner. We propose that the role of SMG-1 in lifespan regulation is at least partly dependent on its function in oxidative stress resistance. Taken together, our results unveil a novel role for SMG-1 in lifespan regulation

    Down-Regulation of DNA Mismatch Repair Enhances Initiation and Growth of Neuroblastoma and Brain Tumour Multicellular Spheroids

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    Multicellular tumour spheroid (MCTS) cultures are excellent model systems for simulating the development and microenvironmental conditions of in vivo tumour growth. Many documented cell lines can generate differentiated MCTS when cultured in suspension or in a non-adhesive environment. While physiological and biochemical properties of MCTS have been extensively characterized, insight into the events and conditions responsible for initiation of these structures is lacking. MCTS are formed by only a small subpopulation of cells during surface-associated growth but the processes responsible for this differentiation are poorly understood and have not been previously studied experimentally. Analysis of gene expression within spheroids has provided clues but to date it is not known if the observed differences are a cause or consequence of MCTS growth. One mechanism linked to tumourigenesis in a number of cancers is genetic instability arising from impaired DNA mismatch repair (MMR). This study aimed to determine the role of MMR in MCTS initiation and development. Using surface-associated N2a and CHLA-02-ATRT culture systems we have investigated the impact of impaired MMR on MCTS growth. Analysis of the DNA MMR genes MLH1 and PMS2 revealed both to be significantly down-regulated at the mRNA level compared with non-spheroid-forming cells. By using small interfering RNA (siRNA) against these genes we show that silencing of MLH1 and PMS2 enhances both MCTS initiation and subsequent expansion. This effect was prolonged over several passages following siRNA transfection. Down-regulation of DNA MMR can contribute to tumour initiation and progression in N2a and CHLA-02-ATRT MCTS models. Studies of surface-associated MCTS differentiation may have broader applications in studying events in the initiation of cancer foci

    Cost-Effectiveness of Pre-Referral Antimalarial, Antibacterial, and Combined Rectal Formulations for Severe Febrile Illness

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    BACKGROUND: Malaria and bacterial infections account for most infectious disease deaths in developing countries. Prompt treatment saves lives, but rapid deterioration often prevents the use of oral therapies; delays in reaching health facilities providing parenteral interventions are common. Rapidly and reliably absorbed antimalarial/antibacterial rectal formulations used in the community could prevent deaths and disabilities. Rectal antimalarial treatments are currently available; rectal antibacterial treatments are yet to be developed. Assessment of the likely cost-effectiveness of these interventions will inform research priorities and implementation. METHODS AND FINDINGS: The burden of malaria and bacterial infections worldwide and in Sub-Saharan and Southern Africa (SSA) and South and South-East Asia (SEA) was summarised using published data. The additional healthcare costs (USD) per death and per Disability Adjusted Life Year (DALY) avoided following pre-referral treatment of severe febrile illness with rectal antimalarials, antibacterials or combined antimalarial/antibacterials in populations at malaria risk in SSA/SEA were assessed. 46 million severe malaria and bacterial infections and 5 million deaths occur worldwide each year, mostly in SSA/SEA. At annual delivery costs of 0.02 dollars/capita and 100% coverage, rectal antimalarials (2 dollars per dose) would avert 240,000 deaths in SSA and 7,000 deaths in SEA at 5 and 177 dollars per DALY avoided, respectively; rectal antibacterials (2 dollars per dose) would avert 130,000 deaths in SSA and 27,000 deaths in SEA at 19 and 97 dollars per DALY avoided, respectively. Combined rectal formulations (2.50 dollars per dose) would avert 370,000 deaths in SSA and 33,000 deaths in SEA at 8 and 79 dollars per DALY avoided, respectively, and are a cost-effective alternative to rectal antimalarials or antibacterials alone. CONCLUSIONS: Antimalarial, antibacterial and combined rectal formulations are likely to be cost-effective interventions for severe febrile illness in the community. Attention should focus on developing effective rectal antibacterials and ensuring that these lifesaving treatments are used in a cost-effective manner

    MCT1-mediated transport of a toxic molecule is an effective strategy for targeting glycolytic tumors

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    There is increasing evidence that oncogenic transformation modifies the metabolic program of cells. A common alteration is the upregulation of glycolysis, and efforts to target glycolytic enzymes for anticancer therapy are under way. Here, we performed a genome-wide haploid genetic screen to identify resistance mechanisms to 3-bromopyruvate (3-BrPA), a drug candidate that inhibits glycolysis in a poorly understood fashion. We identified the SLC16A1 gene product, MCT1, as the main determinant of 3-BrPA sensitivity. MCT1 is necessary and sufficient for 3-BrPA uptake by cancer cells. Additionally, SLC16A1 mRNA levels are the best predictor of 3-BrPA sensitivity and are most elevated in glycolytic cancer cells. Furthermore, forced MCT1 expression in 3-BrPA–resistant cancer cells sensitizes tumor xenografts to 3-BrPA treatment in vivo. Our results identify a potential biomarker for 3-BrPA sensitivity and provide proof of concept that the selectivity of cancer-expressed transporters can be exploited for delivering toxic molecules to tumors.National Institutes of Health (U.S.) (NIH CA103866)Jane Coffin Childs Memorial Fund for Medical Research (Fellowship)National Science Foundation (U.S.) (Fellowship)Howard Hughes Medical Institute (Investigator
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