Semiconductor Bolometers Give Background-Limited Performance

Semiconductor bolometers that are capable of detecting electromagnetic radiation over most or all of the infrared spectrum and that give background-limited performance at operating temperatures from 20 to 300 K have been invented. The term background-limited performance as applied to a bolometer, thermopile, or other infrared detector signifies that the ability to detect infrared signals that originate outside the detector is limited primarily by thermal noise attributable to the background radiation generated external to the bolometer. The signal-to-noise ratios and detectivities of the bolometers and thermopiles available prior to this invention have been lower than those needed for background-limited performance by factors of about 100 and 10, respectively. Like other electrically resistive bolometers, a device according to the invention exhibits an increase in electrical resistance when heated by infrared radiation. Depending on whether the device is operated under the customary constant- current or constant-voltage bias, the increase in electrical resistance can be measured in terms of an increase in voltage across the device or a decrease in current through the device, respectively. In the case of a semiconductor bolometer, it is necessary to filter out visible and shorter-wavelength light that could induce photoconductivity and thereby counteract all or part of the desired infrared- induced increase in resistance. The basic semiconductor material of a bolometer according to the invention is preferably silicon doped with one or more of a number of elements, each of which confers a different variable temperature coefficient of resistance. Suitable dopants include In, Ga, S, Se, Te, B, Al, As, P, and Sb. The concentration of dopant preferably lies in the range between 0.1 and 1,000 parts per billion

Resonant infrared detector with substantially unit quantum efficiency

A resonant infrared detector includes an infrared-active layer which has first and second parallel faces and which absorbs radiation of a given wavelength. The detector also includes a first tuned reflective layer, disposed opposite the first face of the infrared-active layer, which reflects a specific portion of the radiation incident thereon and allows a specific portion of the incident radiation at the given wavelength to reach the infrared-active layer. A second reflective layer, disposed opposite the second face of the infrared-active layer, reflects back into the infrared-active layer substantially all of the radiation at the given wavelength which passes through the infrared-active layer. The reflective layers have the effect of increasing the quantum efficiency of the infrared detector relative to the quantum efficiency of the infrared-active layer alone

Changes in Plasma Potassium During Graded Aerobic Exercise and Two Hours of Recovery

Plasma potassium increases with exercise intensity. Subjects (n=8) were monitored for changes in plasma potas-sium while exercising at progressively increasing steady-state intensities and for two hours of recovery. Plasma po-tassium was significantly increased at 100% of VO2peak compared to 20% and 40% (p<0.01). Plasma potassium at 60 and 120 minutes of recovery from exercise was significantly higher than 6 minutes post exercise (p<0.015). These results support the supposition that high-intensity exercise may lead to hyperkalemia, and also indicates that in-creases in [K + ] occur up to two hours after the cessation of exercise, a newly reported phenomenon. Although, high levels of plasma potassium are known to cause cardiac abnormalities and related events, exercise induced changes in normal healthy adults are not currently believed to have clinical implications

Basic Mechanisms of Arsenic Trioxide (ATO)-Induced Apoptosis in Human Leukemia (HL-60) Cells

<p>Abstract</p> <p>Background</p> <p>Acute promyelocytic leukemia (APL) is a blood cancer that affects people of all ages and strikes about 1,500 patients in the United States each year. The standard treatment of APL has been based on the combined administration of all-trans retinoic acid and chemotherapy including anthracyclins and cytarabine. However, 10-20% of patients relapse, with their disease becoming resistant to conventional treatment. Recently the Food and Drug Administration has approved the use of arsenic trioxide (ATO) or Trisenox for the treatment of APL, based on clinical studies showing a complete remission, especially in relapsed patients. In a recently published study we demonstrated that ATO pharmacology as an anti-cancer drug is associated with its cytotoxic and genotoxic effects in human leukemia cells.</p> <p>Methods</p> <p>In the present study, we further investigated the apoptotic mechanisms of ATO toxicity using the HL-60 cell line as a test model. Apoptosis was measured by flow cytometry analysis of phosphatidylserine externalization (Annexin V assay) and caspase 3 activity, and by DNA laddering assay.</p> <p>Results</p> <p>Flow cytometry data showed a strong dose-response relationship between ATO exposure and Annexin-V positive HL-60 cells. Similarly, a statistically significant and dose-dependent increase (<it>p <</it>0.05) was recorded with regard to caspase 3 activity in HL60 cells undergoing late apoptosis. These results were confirmed by data of DNA laddering assay showing a clear evidence of nucleosomal DNA fragmentation in ATO-treated cells.</p> <p>Conclusion</p> <p>Taken together, our research demonstrated that ATO represents an apoptosis-inducing agent and its apoptotic mechanisms involve phosphatidylserine externalization, caspase 3 activation and nucleosomal DNA fragmentation.</p

Exercise-Induced Glycogen Reduction Increases Muscle Activity

International Journal of Exercise Science 9(3): 336-346, 2016. Intramuscular glycogen stores are an important energy source during extended bouts of strenuous exercise. A substantial reduction in glycogen could influence neural muscular drive and result in a decreasing quality of exercise performance and potentially increased injury rates. The aim of this study was to examine the effect of glycogen reduction on motor drive as determined by the surface electromyogram (EMG) amplitude and median frequency during a cycling graded exercise test. Eight trained cyclists performed a discontinuous cycling graded exercise test to exhaustion under both normal and glycogen reduced conditions. EMG was collected from the vastus lateralis. Repeated measures regression models indicated that EMG amplitudes were elevated at cycling workloads higher than 196 Watts and metabolic workloads higher than 40.8 ml/kg/min, corresponding to 77% VO2max. There was no effect of increases in workload or glycogen reduction on EMG median frequency. Changes in mechanical and metabolic workload had a substantial effect on EMG amplitude (Cohen’s f2 = 0.227 and 0.247, respectively), but not median frequency (Cohen’s f2 = 0.026 and 0.033, respectively). Thus, EMG amplitude is a more effective and reliable measure to examine changes in motor drive during variable workload conditions and metabolic perturbations. The results suggest that healthy glycogen reduced humans require higher levels of muscle activity in order to attain a given mechanical and metabolic workload. This may affect the long term performance of professional and military athletes who need to be able to perform at a high level for extended periods of activity

Insights into physical activity and cardiovascular disease risk in young children: IDEFICS study

Abstract The association between physical activity and cardiovascular disease risk factors in children has been the focus of research for over two decades. The majority of this research has focused on children over 10 years of age with little information on very young children. The data recently published in BMC Medicine by Jiménez-Pavón and colleagues suggest that adverse cardiovascular disease (CVD) risk profiles, as indicated by a clustered risk score for the metabolic syndrome, are evident in very young children (two to six years of age), but differ between the sexes. The authors evaluated the relationship of CVD risk profiles and protective levels of moderate-to-vigorous physical activity (MVPA) and concluded that boys aged six years or younger needed >60 minutes of MVPA per day, whereas boys from six to nine years of age needed >80 minutes of MVPA per day; girls in either age group needed approximately 15 minutes less. Therefore, when clinicians recommend physical activity for children they should evaluate “at risk” children on a case-by-case basis rather than using generalized guidelines.Please see related research: http://www.biomedcentral.com/1741-7015/11/172

Actical Accelerometry Cut-points for Quantifying Levels of Exertion: Comparing Normal and Overweight Adults

Int J Exerc Sci 5(2) : 170-182, 2012. Weight, body fatness and ambulatory pattern all have the potential to affect accelerometer output and cause differences in output between overweight and normal-weight adults. The purpose of this study was to determine if Actical (Philips Respironics, Bend, OR) activity count cut-points for moderate and vigorous intensity exercise are different for overweight adults compared to normal-weight adults. Overweight adults with BMI \u3e25 kg/m² (n=29) and Normal-Weight adults (n=25) walked at 3.2 and 4.8 km∙h-1 and ran at 6.4 km∙h-1 on a treadmill while simultaneously wearing an Actical accelerometer and obtaining measurements of oxygen uptake. Counts per minute (counts∙min-1) were determined at 3 METS (moderate) and 6 METS (vigorous) using ROC curves. The counts∙min-1 at 3 METs was 1726 and 1923 counts∙min-1 for Overweight and Normal-Weight groups, respectively. The cut-points at 6 METs were 4117 and 4032 counts∙min-1 for Overweight and Normal-Weight groups, respectively. The differences between groups were not statistically significant (p\u3e0.73 for both). Correlations between BMI and counts∙min-1 were not significant (p\u3e0.05) at any speed for the Normal-Weight group but were significant at 3.2 and 4.8 km∙h-1 for the Overweight group. Although there appears to be some relationship between activity counts∙min-1 and BMI, the results suggest that similar cut-points may be used for normal weight and overweight adults. However, the greater variability in counts at each speed and lower ROC curve areas for overweight adults suggest that it is harder to classify the activity intensity of overweight subjects compared to normal weight subjects

Toxic Absence: Why Leader Presence Matters in Times of Crisis

Aims. This study examines the importance of senior-leader presence on the “frontline” in times of crisis. Background. The COVID-19 pandemic placed unprecedented demands on nurses charged with delivering critical care. Extant research suggests that the active presence of ward-level leaders has an important role to play in supporting frontline staff and mediating the negative impacts of stress and burnout. There is little evidence on the impact of senior leader presence or absence on the experience of frontline critical care nurses, particularly at times of crisis. Methods. A three-phase qualitative interview study of critical care nurses in the UK and Ireland. A total of 107 semistructured interviews with 54 nurses representing 38 different healthcare units. Results. Senior-leader presence at the time of crisis serves as an important symbol of organisational support. Where senior leaders are not meaningfully present, they risk allowing the necessary pain of difficult work situations to become toxic. Toxicity is manifested with increased staff stress, emotional ills, absence, and turnover. Conclusions. Senior leaders must balance their responsibilities for strategy and structures with the frontline presence required to shape a positive emotional climate. Implications for Nursing Management. Senior managers should consider supplementing their strategic focus with punctuated returns to the floor. Symbolically, leaders who get their hands dirty embody a sense of mutual struggle and practical support. Managerially, time on the floor increases the opportunities for collecting primary data to improve decision-making and support

‘Running Towards the Bullets’: Moral Injury in Critical Care Nursing in the COVID-19 Pandemic

The COVID-19 pandemic placed unprecedented strain on healthcare professionals around the globe, particularly those working in intensive care units. It was reported that instances of moral injury – a betrayal of what is ethically right by those in positions of power – were widespread in these organizational settings. In this paper, we explore these emerging findings to ask: What are the experiences and implications of moral injury in critical care nursing during the pandemic? Drawing on 103 interviews with 54 critical care nurses, we offer insights into the experience of moral injury in a workplace experiencing crisis, focusing on (i) unsafe staffing levels, (ii) inadequate equipment, and (iii) inability to provide patients with a dignified death. We provide accounts of the implications of moral injury ranging from debilitating anxiety to post-traumatic stress disorder and sectioning, as well as widespread feelings of anger and guilt leading to an intention to leave the profession

Executable Architectures and their Application to a Geographically Distributed Air Operations Center

Integrated Architectures and Network Centric Warfare represent two central concepts in the Department of Defense\u27s (DoD) on-going transformation. The true power of integrated architectures is brought to bear when they are combined with simulation to move beyond a static representation and create an executable architecture. This architecture can then be used to experiment with system configurations and parameter values to guide employment decisions. The process of developing and utilizing an executable architecture will be employed to assess an Air Operations Center (AOC). This thesis applies and expands upon the methodology of Dr. Alexander Levis, former Chief Scientist of the Air Force, to the static architecture representing the Aerospace Operations Center (AOC). Using Colored Petri Nets and other simulation tools, an executable architecture for the AOC\u27s Air Tasking Order (ATO) production thread was developed. These models were then used to compare the performance of a current, forward-deployed AOC configuration to three other potential configurations that utilize a network centric environment to deploy a portion of the AOC and provide reach-back capabilities to the non-deployed units. Performance was measured by the amount of time required to execute the ATO cycle under each configuration. Communication requirements were analyzed for each configuration and stochastic delays were modeled for all transactions in which requirements could not be met due to the physical configuration of the AOC elements. All four configurations were found to exhibit statistically different behavior with regard to ATO cycle time