Hummingbird: An Energy-Efficient GPS Receiver for Small Satellites

Global positioning system (GPS) is the most widely adopted localization technique for satellites in low earth orbits (LEOs). To enable many state-of-the-art applications on satellites, the exact position of the satellites is necessary. With the increasing demand for small satellites, the need for a low-power GPS for satellites is also increasing. However, building low-power GPS receivers for small satellites poses significant challenges, mainly due to the high speeds (similar to 7.8 km/s) of satellites and low available energy. While duty cycling the receiver is a possible solution, the high relative Doppler shift among the GPS satellites and the small satellite contributes to an increase in Time to First Fix (TTFF), which negatively impacts energy consumption. Further, if the satellite tumbles, the GPS receiver may not be able to receive signals properly from the GPS satellites, thus leading to an even longer TTFF. In the worst case, the situation may result in no GPS fix due to disorientation of the receiver antenna. In this work, we elucidate the design of a low-cost, low-power GPS receiver for small satellites. We also propose an energy optimization algorithm to improve the TTFF. With the extensive evaluation of our GPS receiver on an operational nanosatellite, we show that up to 96.16% of energy savings can be achieved using our algorithm without significantly compromising (similar to 10 m) the positioning accuracy

Intradialytic hyperalimentation as adjuvant support in pregnant hemodialysis patients: case report and review of the literature

Pregnancy in chronic dialysis patients is unusual and associated with many complications. Infants are often born both prematurely and small for gestational age. We report a case of a 36-year-old diabetic hemodialysis patient G4P3 who had prolonged hyperemesis gravidarum, for whom intradialytic parenteral nutrition (IDPN) was started at week 14 and continued throughout her pregnancy. She delivered a 3.5-kg baby girl at the 36th week of gestation by cesarean section. We discuss the use of IDPN as adjunct therapy for pregnant dialysis patients

Children’s experiences following a CBT intervention to reduce dental anxiety: one year on

Objective: To investigate children’s ongoing experiences of dental care and use of strategies to manage their dental anxiety following cognitive behavioural therapy (CBT). Design: A child self-completed postal questionnaire. Settings: Hospital, community and general dental practice. Subjects: Questionnaires were sent to 44 children, aged 10-17 years who had been referred to specialist services due to their dental anxiety. Intervention: Children had all previously received a guided CBT self-help intervention to reduce their dental anxiety and, on completion of treatment, had been discharged to their referring dentist. Questionnaires were sent out 12-18 months later to ascertain dental attendance patterns and application of any strategies learnt from the previous CBT intervention. Results: 22 responses (50%) were received from 16 girls and 6 boys. 82% had subsequently accessed follow up care with a general dental practitioner and over half of these had undergone a dental procedure, other than a check-up. 91% reported feeling less worried about dental visits, than previously, and described a change in cognition, behaviours, and feelings that allowed them to manage their anxiety better. Conclusions: CBT has positive immediate and longitudinal effects in reducing children’s dental anxiety. The challenge of adopting this evidence-based approach within primary care settings remains

Cardiorespiratory fitness, fatness and the acute blood pressure response to exercise in adolescence

Objective: Exaggerated exercise blood pressure (BP) is associated with cardiovascular risk factors in adolescence. Cardiorespiratory fitness and adiposity (fatness) areindependent contributors to cardiovascular risk, but their interrelated associationswith exercise BP are unknown. This study aimed to determine the relationships between fitness, fatness, and the acute BP response to exercise in a large birth cohort ofadolescents.Methods: 2292 adolescents from the Avon Longitudinal Study of Parents andChildren (aged 17.8 ± 0.4 years, 38.5% male) completed a sub-maximal exercisestep test that allowed fitness (VO2 max) to be determined from workload and heart rateusing a validated equation. Exercise BP was measured immediately on test cessationand fatness calculated as the ratio of total fat mass to total body mass measured byDXA.Results: Post-exercise systolic BP decreased stepwise with tertile of fitness (146(18); 142 (17); 141 (16) mmHg) but increased with tertile of fatness (138 (15); 142(16); 149 (18) mmHg). In separate models, fitness and fatness were associated withpost-exercise systolic BP adjusted for sex, age, height, smoking, and socioeconomicstatus (standardized β: −1.80, 95%CI: −2.64, −0.95 mmHg/SD and 4.31, 95%CI:3.49, 5.13 mmHg/SD). However, when fitness and fatness were included in thesame model, only fatness remained associated with exercise BP (4.65, 95%CI: 3.69,5.61 mmHg/SD).Conclusion: Both fitness and fatness are associated with the acute BP response to exercise in adolescence. The fitness-exercise BP association was not independent of fatness, implying the cardiovascular protective effects of cardiorespiratory fitness mayonly be realized with more favorable body composition

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015

SummaryBackground The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding Bill & Melinda Gates Foundation

Late Cretaceous Vicariance in Gondwanan Amphibians

Overseas dispersals are often invoked when Southern Hemisphere terrestrial and freshwater organism phylogenies do not fit the sequence or timing of Gondwana fragmentation. We used dispersal-vicariance analyses and molecular timetrees to show that two species-rich frog groups, Microhylidae and Natatanura, display congruent patterns of spatial and temporal diversification among Gondwanan plates in the Late Cretaceous, long after the presumed major tectonic break-up events. Because amphibians are notoriously salt-intolerant, these analogies are best explained by simultaneous vicariance, rather than by oceanic dispersal. Hence our results imply Late Cretaceous connections between most adjacent Gondwanan landmasses, an essential concept for biogeographic and palaeomap reconstructions

Corporate constructed and dissent enabling public spheres: differentiating dissensual from consensual corporate social responsibility

I here distinguish dissensual from consensual corporate social responsibility (CSR) on the grounds that the former is more concerned to organize (or portray) corporate-civil society disagreement than it is corporate-civil society agreement. In doing so, I first conceive of consensual CSR, and identify a positive and negative view thereof. Second, I conceive of dissensual CSR, and suggest that it can be actualized through the construction of dissent enabling, rather than consent-oriented, public spheres. Following this, I describe four actor-centred institutional theories-i.e. a sociological, ethical, transformative and economic perspective, respectively-and suggest that an economic perspective is generally well suited to explaining CSR activities at the organizational level. Accordingly, I then use the economic perspective to analyse a dissent enabling public sphere that Shell has constructed, and within which Greenpeace participated. In particular, I explain Shell's employment of dissensual CSR in terms of their core business interests; and identify some potential implications thereof for Shell, Greenpeace, and society more generally. In concluding, I highlight a number of ways in which the present paper can inform future research on business and society interactions