A new multi-beam spectrometer for the Green Bank Telescope (GBT) is being designed and built by a partnership between the National Radio Astronomy Observatory (NRAO) and the University of California ...at Berkeley, and partially funded by a National Science Foundation Advanced Technology Instrumentation grant. The spectrometer is a heterogeneous computing device based on a Field Programmable Gate Array (FPGA) front-end and a heterogeneous compute server backend, comprised of Graphical Processing Units (GPUs) and x86 CPUs. Working together, the hardware in this system provides processing power to analyse up to 8 dual-polarization or 16 single-polarization inputs, at bandwidths of up to 1.25 GHz per input. An aggregate of up to 10 GHz of bandwidth, dual polarization, may be processed with the spectrometer.
A new spectrometer for the Green Bank Telescope (GBT) is being built jointly by the NRAO and the CASPER, University of California, Berkeley. The spectrometer uses 8 bit ADCs and will be capable of ...processing up to 1.25 GHz bandwidth from 8 dual polarized beams. This mode will be used to process data from focal plane arrays. The spectrometer supports observing mode with 8 tunable digital sub-bands within the 1.25 GHz bandwidth. The spectrometer can also be configured to process a bandwidth of up to 10 GHz with 64 tunable sub-bands from a dual polarized beam. The vastly enhanced backend capabilities will support several new science projects with the GBT.
A new spectrometer for the Green Bank Telescope (GBT) is being built jointly by the NRAO and the CASPER, University of California, Berkeley. The spectrometer uses 8 bit ADCs and will be capable of ...processing up to 1.25 GHz bandwidth from 8 dual polarized beams. This mode will be used to process data from focal plane arrays. The spectrometer supports observing mode with 8 tunable digital sub-bands within the 1.25 GHz bandwidth. The spectrometer can also be configured to process a bandwidth of up to 10 GHz with 64 tunable sub-bands from a dual polarized beam. The vastly enhanced backend capabilities will support several new science projects with the GBT.
Little is known about the relationship between body temperature and outcomes in patients with acute respiratory distress syndrome (ARDS). A better understanding of this relationship may provide ...evidence for fever suppression or warming interventions, which are commonly applied in practice.
To examine the relationship between body temperature and mortality in patients with ARDS.
Secondary analysis of body temperature and mortality using data from the ARDS Network Fluid and Catheter Treatment Trial (n = 969). Body temperature at baseline and on study day 2, primary cause of ARDS, severity of illness, and 90-day mortality were analyzed by using multiple logistic regression.
Mean baseline temperature was 37.5°C (SD, 1.1°C; range, 27.2°C-40.7°C). At baseline, fever (≥ 38.3°C) was present in 23% and hypothermia (< 36°C) in 5% of the patients. Body temperature was a significant predictor of 90-day mortality after primary cause of ARDS and score on the Acute Physiology and Chronic Health Evaluation III were adjusted for. Higher temperature was associated with decreased mortality: for every 1°C increase in baseline temperature, the odds of death decreased by 15% (odds ratio, 0.85; 95% CI, 0.73-0.98, P = .03). When patients were divided into 5 temperature groups, mortality was lower with higher temperature (P for trend = .02).
Early in ARDS, fever is associated with improved survival rates. Fever in the acute phase response to lung injury and its relationship to recovery may be an important factor in determining patients' outcome and warrants further study.
Nitrogen oxide (NO) species are markers for oxidative stress that may be pathogenic in acute lung injury (ALI).
We tested two hypotheses in patients with ALI: (1) higher levels of urine NO would be ...associated with worse clinical outcomes, and (2) ventilation with lower VT would reduce urine NO as a result of less stretch injury.
Urine NO levels were measured by chemiluminescence in 566 patients enrolled in the National Heart Lung and Blood Institute Acute Respiratory Distress Syndrome Network trial of 6 ml/kg versus 12 ml/kg VT ventilation. The data were expressed corrected and uncorrected for urine creatinine (Cr).
Higher baseline levels of urine NO to Cr were associated with lower mortality (odds ratio, 0.43 per log(10) increase in the ratio), more ventilator-free days (mean increase, 1.9 d), and more organ-failure-free days (mean increase, 2.3 d) on multivariate analysis (p < 0.05 for all analyses). Similar results were obtained using urine NO alone. NO to Cr levels were higher on Day 3 in the 6 ml/kg than in the 12 ml/kg VT group (p = 0.04).
Contrary to our hypothesis, higher urine NO was associated with improved outcomes in ALI at baseline and after treatment with the 6 ml/kg VT strategy. Higher endogenous NO may reflect less severe lung injury and better preservation of the pulmonary and systemic endothelium or may serve a protective function in patients with ALI.
To determine whether the administration of lisofylline (1-5R-hydroxyhexyl-3,7-dimethylxanthine) would decrease mortality in patients with acute lung injury (ALI) or acute respiratory distress ...syndrome (ARDS).
A prospective, randomized, double-blind, placebo-controlled, multicenter study.
Intensive care units at 21 hospitals at the ten centers constituting the ARDS Clinical Trials Network.
A total of 235 patients who met eligibility criteria were enrolled in the study (116 into the lisofylline group, 119 into the placebo group).
Patients were randomized to receive either lisofylline or placebo. The dose of lisofylline was 3 mg/kg with a maximum dose of 300 mg intravenously every 6 hrs. The intravenous solution of study drug was administered over 10 mins every 6 hrs. Dosing was continued for 20 days or until the patient achieved 48 hrs of unassisted breathing.
The trial was stopped by the Data Safety Monitoring Board for futility at the first scheduled interim analysis. The patient groups had similar characteristics at enrollment. No significant safety concerns were associated with lisofylline therapy. There was no significant difference between groups in the number of patients who had died at 28 days (31.9% lisofylline vs. 24.7% placebo, p = .215). There was no significant difference between the lisofylline and placebo groups in terms of resolution of organ failures, ventilator-free days, infection-related deaths, or development of serious infection during the 28-day study period. The median number of organ failure-free days for the five nonpulmonary organ failures examined (cardiovascular, central nervous system, coagulation, hepatic, and renal) was not different between the lisofylline and placebo groups. Although lisofylline has been reported to decrease circulating free fatty acid levels, we did not find any such treatment effect compared with placebo.
In this study, there was no evidence that lisofylline had beneficial effects in the treatment of established ALI/ARDS.
Desmosine is a stable breakdown product of elastin that can be reliably measured in urine samples. We tested the hypothesis that higher baseline urine desmosine would be associated with higher ...mortality in 579 of 861 patients included in the recent Acute Respiratory Distress Syndrome Network trial of lower tidal volume ventilation (1). We also correlated urine desmosine levels with indexes of disease severity. Finally, we assessed whether urine desmosine was lower in patients who received lower tidal volumes. Desmosine was measured by radioimmunoassay in urine samples from days 0, 1, and 3 of the study. The data were expressed as a ratio of urine desmosine to urine creatinine to control for renal dilution. The results show that higher baseline (day 0) urine desmosine-to-creatinine concentration was associated with a higher risk of death on adjusted analysis (odds ratio 1.36, 95% confidence interval 1.02-1.82, P=0.03). Urine desmosine increased in both ventilator groups from day 0 to day 3, but the average rise was higher in the 12-ml/kg predicted body weight group compared with the 6-ml/kg predicted body weight group (P=0.053, repeated-measures model). In conclusion, patients with acute lung injury ventilated with lower tidal volumes have lower urine desmosine levels, a finding that may reflect reduced extracellular matrix breakdown. These results illustrate the value of evaluating urinary biological markers that may have prognostic and pathogenetic significance in acute lung injury.
Enrolling critically ill patients in clinical trials is challenging. We observed that eligible patients at San Francisco General Hospital (SFGH), a public hospital that cares largely for indigent ...patients, were less likely to be enrolled in a clinical trial of acute lung injury (ALI) than eligible patients at the University of California, San Francisco (UCSF), a university referral center. We examined the reasons for nonenrollment and the impact of the availability of a surrogate decision maker on critical care clinical trials enrollment.
Data collected from the ARDS Network trial of lower vs traditional tidal volume ventilation for patients with ALI was analyzed. Patient demographics and reasons for nonenrollment were analyzed among 531 consecutively screened patients at the two hospitals: UCSF and SFGH.
At UCSF, 1% of screened patients were not enrolled because they lacked surrogates, whereas 18% of screened patients were not enrolled at SFGH because they lacked surrogates. Lack of surrogate was the most common reason for nonenrollment among eligible patients at SFGH.
Critically ill patients with ALI at a public hospital were less likely to be enrolled in a clinical trial than patients at a university hospital primarily because they lacked surrogates. Lack of a surrogate also was a major factor in nonenrollment in other ARDS Network hospitals. In order to provide all affected patients an opportunity to participate in research, innovative strategies for increasing enrollment in critical care research without compromising protection from research risks are needed.
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