Response of tantalum capacitors to fast transient overvoltages

Report describes tests used to determine minimum time for capacitors to fail due to overvoltage and maximum amount of overvoltage that capacitors could sustain without permanent damage

Tantalum capacitor behavior under fast transient overvoltages

Tantalum capacitors were tested to determine failure time when subjected to short-duration, high-voltage surges caused by lightning strikes. Lightning is of concern to NASA because of possible damage to critical spacecraft circuits. The test was designed to determine the minimum time for tantalum capacitor failure and the amount of overvoltage a capacitor could survive, without permanent damage, in 100 microseconds. All tested exhibited good recovery from the transient one-shot pulses with no failure at any voltage, forward or reverse, in less than 25 microseconds

In-flight absolute radiometric calibration of the thematic mapper

The TM multispectral scanner system was calibrated in an absolute manner before launch. To determine the temporal changes of the absolute radiometric calibration of the entire system, spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM collections over White Sands, New Mexico. By entering the measured values in an atmospheric radiative transfer program, the radiance levels of the in four of the spectral bands of the TM were determined. Tables show values for the reflectance of snow at White Sands measured by a modular 8 channel radiometer, and values for exoatmospheric irradiance within the TM passbands, calculated for the Earth-Sun distance using a solar radiometer

In-flight absolute radiometric calibration of the thematic mapper

In order to determine temporal changes of the absolute radiometric calibration of the entire TM system in flight spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM image collections over the White Sands, New Mexico area. By entering the measured values in an atmospheric radiative transfer program, the radiance levels in four of the spectral bands of the TM were determined, band 1:0.45 to 0.52 micrometers, band 2:0.53 to 0.61 micrometers band 3:0.62 to 0.70 micrometers and 4:0.78 to 0.91 micrometers. These levels were compared to the output digital counts from the detectors that sampled the radiometrically measured ground area, thus providing an absolute radiometric calibration of the entire TM system utilizing those detectors

Post-polymerisation modification of bio-derived unsaturated polyester resins via Michael additions of 1,3-dicarbonyls

Post-polymerisation modification of α,β-unsaturated polyesters (UPEs) is useful to deliver polymers with tuneable properties and applications different from their parent backbone. Bio-derivable itaconate unsaturated polyesters, with a range of co-monomers, were modified via a heterogeneously catalysed microwave-assisted Michael addition of pendants, acetylacetone (Hacac) and dimethyl malonate (DMM), to the polymer backbones with very short reaction times. Differential scanning calorimetry analysis showed an increase in the glass-transition temperatures of most of the saturated polyesters considered. Solubility and complexation studies demonstrated metal chelating abilities of the acetylacetone pendant can be retained, even following tethering to a polyester backbone. Additionally, it is demonstrated for the first time that Michael addition with Hacac and DMM can be used to reverse Ordelt saturation, an unwanted side-reaction in the synthesis of UPEs

Cues and knowledge structures used by mental-health professionals when making risk assessments

Background: Research into mental-health risks has tended to focus on epidemiological approaches and to consider pieces of evidence in isolation. Less is known about the particular factors and their patterns of occurrence that influence clinicians’ risk judgements in practice. Aims: To identify the cues used by clinicians to make risk judgements and to explore how these combine within clinicians’ psychological representations of suicide, self-harm, self-neglect, and harm to others. Method: Content analysis was applied to semi-structured interviews conducted with 46 practitioners from various mental-health disciplines, using mind maps to represent the hierarchical relationships of data and concepts. Results: Strong consensus between experts meant their knowledge could be integrated into a single hierarchical structure for each risk. This revealed contrasting emphases between data and concepts underpinning risks, including: reflection and forethought for suicide; motivation for self-harm; situation and context for harm to others; and current presentation for self-neglect. Conclusions: Analysis of experts’ risk-assessment knowledge identified influential cues and their relationships to risks. It can inform development of valid risk-screening decision support systems that combine actuarial evidence with clinical expertise

Prevalence and Predictors of Household Food Insecurity among Adult/Youth Dyads at the Initiation of the iCook 4-H Two-Year Obesity Prevention Study

Objective: Determine food insecurity prevalence and predictors among adult/youth dyads enrolled in a childhood obesity prevention study (iCook 4-H).Methods: The iCook 4-H intervention was designed for youth (9-10 years old) and their adult main meals preparer to cook, eat, and play together. Although not an inclusion criteria, diverse, low income, and/or rural families were the target during recruitment. At baseline, adults completed surveys on food insecurity, socioeconomic and demographic characteristics and youth anthropometrics were collected with body mass index (BMI) calculated. Descriptive statistics were computed and chi-square analysis was conducted to test differences between potential predictors and food insecurity. Binomial logistic regression was used to assess the relationship between food insecurity and its predictors.Results: Thirty-four percent of households (n=71 of 206) were food insecure. Youth were primarily white (69.9%) and normal weight (58.3%). Adults were also primarily white (74.8%), overweight or obese (67.9%), married (68.9%), not participating in government assistance programs (57.8%), and held no college degree (55.3%). Based on the logistic regression model, households with a non-white youth (OR=13.53; 95% CI=3.33, 55.05), an adult without a college degree (OR=5.62; 95% CI=2.01, 15.73), and government assistance program participation (OR=5.63; 95% CI=2.63, 12.07) were significantly associated with household food insecurity. However, there was no significant association with BMI found (youth p=0.167; adult p=0.179).Conclusion: Consistent with previous findings, household food insecurity status was associated with youth race, adult education, and government assistance program participation. In contrast, no relationship between BMI and food insecurity status was observed in this study, which warrants further investigation

What lies beneath? The role of informal and hidden networks in the management of crises

Crisis management research traditionally focuses on the role of formal communication networks in the escalation and management of organisational crises. Here, we consider instead informal and unobservable networks. The paper explores how hidden informal exchanges can impact upon organisational decision-making and performance, particularly around inter-agency working, as knowledge distributed across organisations and shared between organisations is often shared through informal means and not captured effectively through the formal decision-making processes. Early warnings and weak signals about potential risks and crises are therefore often missed. We consider the implications of these dynamics in terms of crisis avoidance and crisis management

Cooking Frequency Associated With Dietary Quality in iCook-4H Youth Participants at Baseline

Background: Increased intakes of ready-made and fast foods paralleled with decreased homemade food consumption have been associated with increased rates of obesity. Researchers have shown associations between cooking self-efficacy (SE) and cooking frequency (CF) with dietary quality and weight status. Some cooking interventions have shown positive associations with dietary outcomes, such as increased fruit and vegetable intake and decreased fast food consumption. There is still much unknown about SE and CF, especially among youth. Objective: Determine baseline SE and CF and the associations with dietary quality and body mass index (BMI) of youth enrolled in iCook 4H. Methods: Youth (n=228, ages 9-10 years) completed online surveys assessing SE, CF, dietary quality, and demographics. Anthropometrics were collected to calculate BMI-for-age percentiles and weight categories. Descriptive statistics were completed for CF, SE, BMI categories, and demographics. Differences in CF and SE by sex, race, and participation in government assistance programs were determined through independent-sample t tests. Pearson correlations were used to assess the association between dietary quality and CF and SE. Associations between CF and dietary quality were assessed further through 2-way analyses of variance (ANOVAs) that included CF and sex and CF and race as independent variables. Associations between SE and CF and BMI were assessed through ANOVAs. Results: Thirty-seven percent of youth were overweight or obese. Females reported significantly higher CF than males (P=.042). Cooking frequency was positively associated with dietary quality (P \u3c .001), but BMI was not associated with dietary quality. SE was not associated with dietary quality or BMI. Conclusion: Based on results, CF was positively associated with dietary quality among youth. More research is needed to assess how different types of cooking relate to diet and BMI. Interventions are needed to determine whether increasing CF leads to better diet outcomes