Key results of the mini-dome Fresnel lens concentrator array development program under recently completed NASA and SDIO SBIR projects

Since 1986, ENTECH and the NASA Lewis Research Center have been developing a new photovoltaic concentrator system for space power applications. The unique refractive system uses small, dome shaped Fresnel lenses to focus sunlight onto high efficiency photovoltaic concentrator cells which use prismatic cell covers to further increase their performance. Highlights of the five-year development include near Air Mass Zero (AM0) Lear Jet flight testing of mini-dome lenses (90 pct. net optical efficiency achieved); tests verifying sun-pointing error tolerance with negligible power loss; simulator testing of prism-covered GaAs concentrator cells (24 pct. AM0 efficiency); testing of prism-covered Boeing GaAs/GaSb tandem cells (31 pct. AM0 efficiency); and fabrication and outdoor testing of a 36-lens/cell element panel. These test results have confirmed previous analytical predictions which indicate substantial performance improvements for this technology over current array systems. Based on program results to date, it appears than an array power density of 300 watts/sq m and a specific power of 100 watts/kg can be achieved in the near term. All components of the array appear to be readily manufacturable from space-durable materials at reasonable cost. A concise review is presented of the key results leading to the current array, and further development plans for the future are briefly discussed

Accuracy of at-sea commercial size grading of tiger prawns (Penaeus esculentus and P-semisulcatus) in the Australian northern prawn fishery

The size-frequency distribution of the commercial catch is often used as the basis of fisheries stock assessments (Paul and Morgan, 1987; Gulland and Rosenberg, 1992) because most dynamic processes of populations (growth, survival, recruitment) are reflected in changes in this distribution. The data are generally collected, often at great expense, by sampling the catch at landing sites and markets, or onboard fishing vessels. Size-frequency distributions of prawns (Penaeus esculentus and P. semisulcatus) can also be obtained from fish processors, who grade landings by size. These data are easier and cheaper to obtain than research samples, but unfortunately they are also considered less accurate and lack spatial information. However, they have been used in stock assessment of prawns in Kuwait (Jones and van Zalinge, 1981) and Malaysia (Simpson and Kong, 1978). It is often difficult to relate size data obtained from a processor to time and place of capture of the prawns, but this is not the case when the product is packed onboard, as in Australia's northern prawn fishery (NPF). Trawler operators in the NPF have voluntarily recorded size composition since 1985, when provision for this was made in operators' daily logbooks (between 30% and 45% of the tiger prawn catch reported in the logbooks contain size information). These books are therefore the most comprehensive source of information on the spatial and temporal size distribution of the commercial catch of the NPF. Present assessments of the fishery are based on deterministic growth and deterministic seasonal recruitment patterns (Wang and Die, 1996) and do not use size-structured data. If available, these data would help relax the recruitment and improve current stock assessments of the NPF. Before the size data recorded in the logbooks can be used, however, the accuracy of size grading at sea needs to the assessed. This paper examines the accuracy of grading tiger prawns, by using data collected from a private firm, A. Raptis and Sons, that operates a large modern processing factory that regularly assesses the onboard grading of product purchased from NPF trawler operators. Although the work presented here relates specifically to the NPF, the practice of onboard size grading is widespread in other fisheries around the world. Therefore our methods have potential application to other fisheries

An update on the development of a line-focus refractive concentrator array

Concentrator arrays offer a number of generic benefits for space (i.e. high array efficiency, protection from space radiation effects, minimized plasma interactions, etc.). The line-focus refractive concept, however, also offers two very important advantages: (1) relaxation of precise array tracking requirements to only a single axis and (2) low-cost mass production of the lens material. The linear refractive concentrator can be designed to provide an essentially flat response over a wide range of longitudinal errors for satellites having only single-axis tracking capability. New panel designs emphasize light weight, high stiffness, storability, and ease of manufacturing and assembly. This paper addresses the current status of the concentrator program with special emphasis on the design implications, and flexibility, of using a linear refractive concentrator lens as well as details recent fabrication of prototype hardware

Influence of a cattle access point on temporal changes in stream turbidity

Unrestricted cattle access can have negative impacts on aquatic systems, including increases in stream water turbidity and suspended sediment levels. Many agri-environmental policies require the exclusion of livestock from waterbodies; however, data that quantify these impacts are scarce. This study used sensors measuring turbidity, a proxy for suspended sediment, together with motion-detecting cameras, to examine the influence of cattle in-stream activity on water quality in north-east Ireland. Two nephelometers, which automatically measured and logged turbidity, were placed upstream and downstream of a cattle access point in July 2017, while cameras were used to record cattle behaviour. A second deployment was made during February 2018 when cattle were absent. During low flows, frequent short-lived increases in turbidity were recorded at the downstream nephelometer only. These coincided with cattle accessing the water. There was a significant positive relationship between the longitudinal differences (downstream − upstream) in turbidity and the total number of cattle accessing the stream. There was no relationship between turbidity and stream discharge in July (when cattle were present), although that period was dominated by lower flow levels, with only 2 days in which discharge increased above baseflow. In contrast, there were no similar short-lived increases in turbidity in February 2018 when cattle were absent from the field, but there was a strong significant positive relationship between stream discharge and turbidity. These results highlight the consequences of cattle access for water column turbidity levels, particularly during periods of low streamflow, and therefore inform future agri-environmental policy in Ireland

Mucoactive agents for acute respiratory failure in the critically ill: a systematic review and meta-analysis

Purpose Acute respiratory failure (ARF) is a common cause of admission to intensive care units (ICUs). Mucoactive agents are medications that promote mucus clearance and are frequently administered in patients with ARF, despite a lack of evidence to underpin clinical decision making. The aim of this systematic review was to determine if the use of mucoactive agents in patients with ARF improves clinical outcomes. Methods We searched electronic and grey literature (January 2020). Two reviewers independently screened, selected, extracted data and quality assessed studies. We included trials of adults receiving ventilatory support for ARF and involving at least one mucoactive agent compared with placebo or standard care. Outcomes included duration of mechanical ventilation. Meta-analysis was undertaken using random-effects modelling and certainty of the evidence was assessed using Grades of Recommendation, Assessment, Development and Evaluation. Results Thirteen randomised controlled trials were included (1712 patients), investigating four different mucoactive agents. Mucoactive agents showed no effect on duration of mechanical ventilation (seven trials, mean difference (MD)-1.34, 95% CI-2.97 to 0.29, I 2 =82%, very low certainty) or mortality, hospital stay and ventilator-free days. There was an effect on reducing ICU length of stay in the mucoactive agent groups (10 trials, MD-3.22, 95% CI-5.49 to-0.96, I 2 =89%, very low certainty). Conclusion Our findings do not support the use of mucoactive agents in critically ill patients with ARF. The existing evidence is of low quality. High-quality randomised controlled trials are needed to determine the role of specific mucoactive agents in critically ill patients with ARF. PROSPERO registration number CRD42018095408

Search for the Decays B^0 -> D^{(*)+} D^{(*)-}

Using the CLEO-II data set we have searched for the Cabibbo-suppressed decays B^0 -> D^{(*)+} D^{(*)-}. For the decay B^0 -> D^{*+} D^{*-}, we observe one candidate signal event, with an expected background of 0.022 +/- 0.011 events. This yield corresponds to a branching fraction of Br(B^0 -> D^{*+} D^{*-}) = (5.3^{+7.1}_{-3.7}(stat) +/- 1.0(syst)) x 10^{-4} and an upper limit of Br(B^0 -> D^{*+} D^{*-}) D^{*\pm} D^\mp and B^0 -> D^+ D^-, no significant excess of signal above the expected background level is seen, and we calculate the 90% CL upper limits on the branching fractions to be Br(B^0 -> D^{*\pm} D^\mp) D^+ D^-) < 1.2 x 10^{-3}.Comment: 12 page postscript file also available through http://w4.lns.cornell.edu/public/CLNS, submitted to Physical Review Letter

Observation of the Decay Ds+→ωπ+D_{s}^{+}\to \omega\pi^{+}

Using e+e- annihilation data collected by the CLEO~II detector at CESR, we have observed the decay Ds+ to omega pi+. This final state may be produced through the annihilation decay of the Ds+, or through final state interactions. We find a branching ratio of [Gamma(Ds+ to omega pi+)/Gamma(Ds+ to eta pi+)]=0.16+-0.04+-0.03, where the first error is statistical and the second is systematic.Comment: 9 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Successful Completion of the Top-off Upgrade of the Advanced Light Source

An upgrade of the Advanced Light Source to enable top-off operation has been completed during the last four years. The final work centered around radiation safety aspects, culminating in a systematic proof that top-off operation is equally safe as decaying beam operation. Commissioning and transition to full user operations happened in late 2008 and early 2009. Top-off operation at the ALS provides a very large increase in time-averaged brightness (by about a factor of 10) as well as improvements in beam stability. The following sections provide an overview of the radiation safety rationale, commissioning results, as well as experience in user operations

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p&lt;0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p&lt;0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding