3,192 research outputs found

    Simulation of the response of a silicon pixel detector

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    A model to simulate the response of a silicon pixel detector is described. The effects of geometrical charge sharing, electronic noise threshold dispersion, capacitive coupling between pixel channels and d -rays production have been taken into account. The model has been tested on the Omega3chip, which is the direct predecessor of the ALICE pixel detector, to be used in the inner tracking system of the ALICE experiment. The model is able to reproduce the experimental data and the resulting parameters are consistent with the measurements made on the Omega3chip. Key words:silicon pixel, simulation PACS:07.05.T,29.40.

    Anti-vascular endothelial growth factor for diabetic macular oedema.

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    BACKGROUND: Diabetic macular oedema (DMO) is a common complication of diabetic retinopathy. Although grid or focal laser photocoagulation has been shown to reduce the risk of visual loss in DMO, or clinically significant macular oedema (CSMO), vision is rarely improved. Antiangiogenic therapy with anti-vascular endothelial growth factor (anti-VEGF) modalities is used to try to improve vision in people with DMO. OBJECTIVES: To investigate the effects in preserving and improving vision and acceptability, including the safety, compliance with therapy and quality of life, of antiangiogenic therapy with anti-VEGF modalities for the treatment of DMO. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 3), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to April 2014), EMBASE (January 1980 to April 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to April 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 April 2014. SELECTION CRITERIA: We included randomised controlled trials (RCTs) comparing any antiangiogenic drugs with an anti-VEGF mechanism of action versus another treatment, sham treatment or no treatment in people with DMO. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by The Cochrane Collaboration. The risk ratios (RR) for visual loss and visual gain of three or more lines of logMAR visual acuity were estimated at one year of follow-up (plus or minus six months) after treatment initiation. MAIN RESULTS: Eighteen studies provided data on four comparisons of interest in this review. Participants in the trials had central DMO and moderate vision loss.Compared with grid laser photocoagulation, people treated with antiangiogenic therapy were more likely to gain 3 or more lines of vision at one year (RR 3.6, 95% confidence interval (CI) 2.7 to 4.8, 10 studies, 1333 cases, high quality evidence) and less likely to lose 3 or more lines of vision (RR 0.11, 95% CI 0.05 to 0.24, 7 studies, 1086 cases, high quality evidence). In meta-analyses, no significant subgroup difference was demonstrated between bevacizumab, ranibizumab and aflibercept for the two primary outcomes, but there was little power to detect a difference. The quality of the evidence was judged to be high, because the effect was large, precisely measured and did not vary across studies, although some studies were at high or unclear risk of bias for one or more domains. Regarding absolute benefit, we estimated that 8 out of 100 participants with DMO may gain 3 or more lines of visual acuity using photocoagulation whereas 28 would do so with antiangiogenic therapy, meaning that 100 participants need to be treated with antiangiogenic therapy to allow 20 more people (95% CI 13 to 29) to markedly improve their vision after one year. People treated with anti-VEGF on average had 1.6 lines better vision (95% CI 1.4 to 1.8) after one year compared to laser photocoagulation (9 studies, 1292 cases, high quality evidence). To achieve this result, seven to nine injections were delivered in the first year and three or four in the second, in larger studies adopting either as needed regimens with monthly monitoring or fixed regimens.In other analyses antiangiogenic therapy was more effective than sham (3 studies on 497 analysed participants, high quality evidence) and ranibizumab associated with laser was more effective than laser alone (4 studies on 919 participants, high quality evidence).Ocular severe adverse events, such as endophthalmitis, were rare in the included studies. Meta-analyses conducted for all antiangiogenic drugs compared with either sham or photocoagulation did not show a significant difference regarding serious systemic adverse events (15 studies, 441 events in 2985 participants, RR 0.98, 95% CI 0.83 to 1.17), arterial thromboembolic events (14 studies, 129 events in 3034 participants, RR 0.89, 95% CI 0.63 to 1.25) and overall mortality (63 events in 3562 participants, RR 0.88, 95% CI 0.52 to 1.47). We judged the quality of the evidence on adverse effects as moderate due to partial reporting of safety data and the exclusion of participants with previous cardiovascular events in some studies. AUTHORS' CONCLUSIONS: There is high quality evidence that antiangiogenic drugs provide a benefit compared to current therapeutic options for DMO, that is grid laser photocoagulation, in clinical trial populations at one or two years. Future research should investigate differences between drugs, effectiveness under real-world monitoring and treatment conditions, and safety in high-risk populations, particularly regarding cardiovascular risk

    A tip-tilt hardware-in-the-loop air-bearing test bed with physical emulation of the relative orbital dynamics

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    29th AAS/AIAA Space Flight Mechanics Meeting: Ka’anapali, Maui, Hawaii, U.S.A. Volume: Advances in the Astronautical Sciences (Vol. 168, pp. 3781–3799). Univelt Inc.A new hardware-in-the-loop (HIL) air bearing testbed that is capable of physically emulating the relative orbital dynamics is presented. Typically, air bearing testbeds consist of test vehicles operating on top of a planar and horizontally-leveled sur face. These test vehicles use air bearings to reduce the friction with the operating surface to negligible levels. The low friction, combined with the horizontally leveled surface, creates a low residual acceleration environment. These dynamics are representative of the environment that spacecraft experience during close proximity maneuvers. To extend the applicability of planar air bearing test beds to longer maneuvers or separations relative orbital dynamics need to be emulated. In this paper, using Hill-Clohessy-Wilshire dynamics, we emulated the relative orbital dynamics of a real spacecraft using a scaled Floating Spacecraft Simulator (FSS) on a dynamically inclined operating surface. The mathematical constructs of the tilt angles, screw height displacements and scaling parameters are developed via Euler’s rotation theorem, Buckingham’s Pi theorem and the similarity principle. The applicability of the new idea is demonstrated via a circumnavigation maneuver scenario of a spacecraft in a Low Earth Orbit (LEO). The simulation results show the viability and suitability of the new approach

    A convex-programming-based guidance algorithm to capture a tumbling object on orbit using a spacecraft equipped with a robotic manipulator

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    An algorithm to guide the capture of a tumbling resident space object by a spacecraft equipped with a robotic manipulator is presented. A solution to the guidance problem is found by solving a collection of convex programming problems. As convex programming offers deterministic convergence properties, this algorithm is suitable for onboard implementation and real-time use. A set of hardware-in-the-loop experiments substantiates this claim. To cast the guidance problem as a collection of convex programming problems, the capture maneuver is divided into two simultaneously occurring sub-maneuvers: a system-wide translation and an internal re-configuration. These two sub-maneuvers are optimized in two consecutive steps. A sequential convex programming procedure, overcoming the presence of non-convex constraints and nonlinear dynamics, is used on both optimization steps. A proof of convergence is offered for the system-wide translation, while a set of structured heuristics—trust regions—is used for the optimization of the internal re-configuration sub-maneuver. Videos of the numerically simulated and experimentally demonstrated maneuvers are included as supplementary material

    Anti-vascular endothelial growth factor for diabetic macular oedema: A network meta-analysis

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    BACKGROUND: Diabetic macular oedema (DMO) is a common complication of diabetic retinopathy. Antiangiogenic therapy with anti-vascular endothelial growth factor (anti-VEGF) modalities can reduce oedema and thereby improve vision and prevent further visual loss. These drugs have replaced laser photocoagulation as the standard of care for people with DMO. OBJECTIVES: The 2014 update of this review found high-quality evidence of benefit with antiangiogenic therapy with anti-VEGF modalities, compared to laser photocoagulation, for the treatment of DMO.The objective of this updated review is to compare the effectiveness and safety of the different anti-VEGF drugs in preserving and improving vision and quality of life using network meta-analysis methods. SEARCH METHODS: We searched various electronic databases on 26 April 2017. SELECTION CRITERIA: We included randomised controlled trials (RCTs) that compared any anti-angiogenic drug with an anti-VEGF mechanism of action versus another anti-VEGF drug, another treatment, sham or no treatment in people with DMO. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods for pair-wise meta-analysis and we augmented this evidence using network meta-analysis methods. We focused on the relative efficacy and safety of the three most commonly used drugs as interventions of direct interest for practice: aflibercept and ranibizumab, used on-label; and off-label bevacizumab.We collected data on three efficacy outcomes (gain of 15 or more Early Treatment Diabetic Retinopathy Study (ETDRS) letters; mean change in best-corrected visual acuity (BCVA); mean change in central retinal thickness (CRT)), three safety outcomes (all severe systemic adverse events (SSAEs); all-cause death; arterial thromboembolic events) and quality of life.We used Stata 'network' meta-analysis package for all analyses. We investigated the risk of bias of mixed comparisons based on the variance contribution of each study, having assigned an overall risk of bias to each study. MAIN RESULTS: Twenty-four studies included 6007 participants with DMO and moderate vision loss, of which two studies randomised 265 eyes of 230 participants and one was a cross-over study on 56 participants (62 eyes) that was treated as a parallel-arm trial. Data were collected on drugs of direct interest from three studies on aflibercept (975 eyes), eight studies on bevacizumab (515 eyes), and 14 studies on ranibizumab (1518 eyes). As treatments of indirect interest or legacy treatment we included three studies on pegaptanib (541 eyes), five studies on ranibizumab plus prompt laser (557 eyes), one study on ranibizumab plus deferred laser (188 eyes), 13 studies on laser photocoagulation (936 eyes) and six studies on sham treatment (793 eyes).Aflibercept, bevacizumab and ranibizumab were all more effective than laser for improving vision by 3 or more lines after one year (high-certainty evidence). Approximately one in 10 people improve vision with laser, and about three in 10 people improve with anti-VEGF treatment: risk ratio (RR) versus laser 3.66 (95% confidence interval (CI) 2.79 to 4.79) for aflibercept; RR 2.47 (95% CI 1.81 to 3.37) for bevacizumab; RR 2.76 (95% CI 2.12 to 3.59) for ranibizumab. On average there was no change in visual acuity (VA) with laser after one year, compared with a gain of 1 or 2 lines with anti-VEGF treatment: laser versus aflibercept mean difference (MD) -0.20 (95% CI -0.22 to -0.17) logMAR; versus bevacizumab MD -0.12 (95% CI -0.15 to -0.09) logMAR; versus ranibizumab MD -0.12 (95% CI -0.14 to -0.10) logMAR. The certainty of the evidence was high for the comparison of aflibercept and ranibizumab with laser and moderate for bevacizumab comparison with laser due to inconsistency between the indirect and direct evidence.People receiving ranibizumab were less likely to gain 3 or more lines of VA at one year compared with aflibercept: RR 0.75 (95% CI 0.60 to 0.94), moderate-certainty evidence. For every 1000 people treated with aflibercept, 92 fewer would gain 3 or more lines of VA at one year if treated with ranibizumab (22 to 148 fewer). On average people receiving ranibizumab had worse VA at one year (MD 0.08 logMAR units, 95% CI 0.05 to 0.11), moderate-certainty evidence; and higher CRT (MD 39 µm, 95% CI 2 µm to 76 µm; low-certainty evidence). Ranibizumab and bevacizumab were comparable with respect to aflibercept and did not differ in terms of VA: RR of gain of 3 or more lines of VA at one year 1.11 (95% CI 0.87 to 1.43), moderate-certainty evidence, and difference in change in VA was 0.00 (95% CI -0.02 to 0.03) logMAR, moderate-certainty evidence. CRT reduction favoured ranibizumab by -29 µm (95% CI -58 µm to -1 µm, low-certainty evidence). There was no evidence of overall statistical inconsistency in our analyses.The previous version of this review found moderate-certainty evidence of good safety of antiangiogenic drugs versus control. This update used data at the longest available follow-up (one or two years) and found that aflibercept, ranibizumab and bevacizumab do not differ regarding systemic serious adverse events (SSAEs) (moderate- or high-certainty evidence). However, risk of bias was variable, loop inconsistency could be found and estimates were not precise enough on relative safety regarding less frequent events such as arterial thromboembolic events or death (low- or very low-certainty evidence).Two-year data were available and reported in only four RCTs in this review. Most industry-sponsored studies were open-label after one year. One large publicly-funded study compared the three drugs at two years and found no difference. AUTHORS' CONCLUSIONS: Anti-VEGF drugs are effective at improving vision in people with DMO with three to four in every 10 people likely to experience an improvement of 3 or more lines VA at one year. There is moderate-certainty evidence that aflibercept confers some advantage over ranibizumab and bevacizumab in people with DMO at one year in visual and anatomic terms. Relative effects among anti-VEGF drugs at two years are less well known, since most studies were short term. Evidence from RCTs may not apply to real-world practice, where people in need of antiangiogenic treatment are often under-treated and under-monitored.We found no signals of differences in overall safety between the three antiangiogenic drugs that are currently available to treat DMO, but our estimates are imprecise for cardiovascular events and death

    Investigating the features of PDO green hams during salting: Insights for new markers and genomic regions in commercial hybrid pigs

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    Protected Designation of Origin (PDO) dry-cured hams production is greatly dependent on raw meat quality. This study was performed to identify genetic markers associated with the quality of dry-cured ham. Carcass traits of 229 heavy pigs belonging to three commercial genetic lines were registered (weight, EUROP classification). Phenotypic traits (Semimembranosus muscle ultimate pH, ham weight and lean meat content, adsorbed salt) of the corresponding thighs, undergone PDO ham process in three different plants, were measured, using a fast and non-invasive technology. Green ham weight and lean meat percentage influenced the estimated salt content and the weight loss during salting, even if the processing plant greatly affected the variability of the measured ham traits. The genomic data were obtained with the GeneSeek Genomic Profiler (GGP) 70k HD Porcine Array, using the slaughter day and the sex of the animals in the statistical analyses. The phenotypic traits were associated with the genotypes through GenAbel software. The results showed that 18 SNPs located on nine porcine chromosomes were found to be associated with nine phenotypic traits, mainly related to ham weight loss during salting. New associations were found between markers in the genes Neural Precursor Cell Expressed Developmentally Down-Regulated 9 (NEDD9, SSC7), T-Cell Lymphoma Invasion and Metastasis 2 (TIAM2, SSC1), and the ham quality traits. After validation, these SNPs may be useful to improve the quality of thighs for the production of PDO dry-cured hams
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