15 research outputs found

    Effects of Long-Term Evolution Waveform on Synthetic Aperture Radar Image Quality Metrics

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    As a greater demand by the private sector for bandwidth drives spectrum allocations away from defense, new methods for coexistence in the spectrum are being explored. One of the prominent areas in defense for this coexistence is passive radar. This mode of radar system allows for data collection by referencing signals already established in the environment of interest. Some of the most prolific signals currently available are those used for mobile communication networks. In particular, Long- Term Evolution (LTE) is a common waveform that could be leveraged for discrete collection of image intelligence. Seeking to build a base of knowledge, simulations of synthetic aperture radar (SAR) systems are carried out using the LTE framework. Variations in waveform content, structure, and signal components are established and used to generate point-spread function (PSF) responses characterizing the image do- main impacts of given fluctuations. Overall, PSF responses for most variations are highly similar, incurring slight losses as pulses contain varied data types and slight gains when maximizing the amount of user data contained in pulses. Notable side- lobes in range profiles occur at predictable intervals and may be easily managed for adequately-sized scenes. Peak sidelobe ratio (PSLR) and integrated sidelobe ratio (ISLR) results show marginal improvement when pulses are varied over the aperture. Range and cross-range resolution, while remaining mostly unchanged throughout variations, are observed to be worse in simulation than is expected. The work presented here is meant to serve as a starting point of overall LTE characterization as a radar waveform and establish basic metrics of comparison for future efforts

    Is biotechnology (more) acceptable when it enables a reduction in phytosanitary treatments? A European comparison of the acceptability of transgenesis and cisgenesis

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    Reduced pesticide use is one of the reasons given by Europeans for accepting new genetic engineering techniques. According to the advocates of these techniques, consumers are likely to embrace the application of cisgenesis to apple trees. In order to verify the acceptability of these techniques, we estimate a Bayesian multilevel structural equation model, which takes into account the multidimensional nature of acceptability and individual, national, and European effects, using data from the Eurobarometer 2010 73.1 on science. The results underline the persistence of clear differences between European countries and whilst showing considerable defiance, a relatively wider acceptability of vertical gene transfer as a means of reducing phytosanitary treatments, compared to horizontal transfer

    Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

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    Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

    Multi-criteria decision analysis with goal programming in engineering, management and social sciences: a state-of-the art review

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    Randomized, placebo‐controlled, phase 3 study of perifosine combined with bortezomib and dexamethasone in patients with relapsed, refractory multiple myeloma previously treated with bortezomib

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    Abstract Perifosine, an investigational, oral, synthetic alkylphospholipid, inhibits signal transduction pathways of relevance in multiple myeloma (MM) including PI3K/Akt. Perifosine demonstrated anti‐MM activity in preclinical studies and encouraging early‐phase clinical activity in combination with bortezomib. A randomized, double‐blind, placebo‐controlled phase 3 study was conducted to evaluate addition of perifosine to bortezomib‐dexamethasone in MM patients with one to four prior therapies who had relapsed following previous bortezomib‐based therapy. The primary endpoint was progression‐free survival (PFS). The study was discontinued at planned interim analysis, with 135 patients enrolled. Median PFS was 22.7 weeks (95% confidence interval 16·0–45·4) in the perifosine arm and 39.0 weeks (18.3–50.1) in the placebo arm (hazard ratio 1.269 [0.817–1.969]; P = .287); overall response rates were 20% and 27%, respectively. Conversely, median overall survival (OS) was 141.9 weeks and 83.3 weeks (hazard ratio 0.734 [0.380–1.419]; P = .356). Overall, 61% and 55% of patients in the perifosine and placebo arms reported grade 3/4 adverse events, including thrombocytopenia (26% vs 14%), anemia (7% vs 8%), hyponatremia (6% vs 8%), and pneumonia (9% vs 3%). These findings demonstrate no PFS benefit from the addition of perifosine to bortezomib‐dexamethasone in this study of relapsed/refractory MM, but comparable safety and OS
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