1,886 research outputs found
Mission safety evaluation report for STS-31, postflight edition
Mission safety factors relative to Space Transportation System (STS) Mission 31 are discussed. In addition to a mission summary, safety risk factors and inflight anomalies are discussed
A quasi classical approach to fully differential ionization cross sections
A classical approximation to time dependent quantum mechanical scattering in
the M\o{}ller formalism is presented. Numerically, our approach is similar to a
standard Classical-Trajectory-Monte-Carlo calculation. Conceptually, however,
our formulation allows one to release the restriction to stationary initial
distributions. This is achieved by a classical forward-backward propagation
technique. As a first application and for comparison with experiment we present
fully differential cross sections for electron impact ionization of atomic
hydrogen in the Erhardt geometry.Comment: 6 pages, 2 figure
Surprising variations in the rotation of the chemically peculiar stars CU Virginis and V901 Orionis
CU Vir and V901 Ori belong among these few magnetic chemically peculiar stars
whose rotation periods vary on timescales of decades. We aim to study the
stability of the periods in CU Vir and V901 Ori using all accessible
observational data containing phase information. We collected all available
relevant archived observations supplemented with our new measurements of these
stars and analysed the period variations of the stars using a novel method that
allows for the combination of data of diverse sorts. We found that the shapes
of their phase curves were constant, while the periods were changing. Both
stars exhibit alternating intervals of rotational braking and acceleration. The
rotation period of CU Vir was gradually shortening until the year 1968, when it
reached its local minimum of 0.52067198 d. The period then started increasing,
reaching its local maximum of 0.5207163 d in the year 2005. Since that time the
rotation has begun to accelerate again. We also found much smaller period
changes in CU Vir on a timescale of several years. The rotation period of V901
Ori was increasing for the past quarter-century, reaching a maximum of 1.538771
d in the year 2003, when the rotation period began to decrease. A theoretically
unexpected alternating variability of rotation periods in these stars would
remove the spin-down time paradox and brings a new insight into structure and
evolution of magnetic upper-main-sequence stars.Comment: 5 pages, 3 figure
The Comparative Political Economy of Basel III in Europe
The Basel III Accord was the centrepiece of the international regulatory response to the global financial crisis, setting new capital requirements for internationally active banks. This paper explains the divergent preferences on Basel III of national regulators in three countries that approximate what are frequently presented as distinct varieties of capitalism in Europe — Germany, the United Kingdom and France. It is argued that national regulators setting post crisis capital requirements had to reconcile three inter-related and potentially conflicting objectives: banking sector stability, the competitiveness of national banks and short to medium term economic growth. The different national preferences on Basel III reflected how different national regulators defined and pursued these objectives, which in turn reflected the structure of national banking systems — specifically, systemic patterns of bank capital and bank-industry ties
The microbiology of rebuilding soils with water treatment residual co‐amendments: Risks and benefits
Water treatment residuals (WTR) are sludges from the potable water treatment process, currently largely destined for landfill. This waste can be diverted to rebuild degraded soils, aligning with the UN's Sustainable Development Goals 12 (Consumption and Production) and 15 (Terrestrial Ecosystems). Biosolids are tested against stringent pathogen guidelines, yet few studies have explored the microbial risk of WTR land application, despite anthropogenic impacts on water treatment. Here, the microbial risks and benefits of amending nutrient-poor sandy soil with WTR were explored. It was shown that the culturable pathogen load of wet and dry WTR did not warrant pre-processing before land application, according to South African national quality guidelines, with fecal coliforms not exceeding 104 CFU/gdw in wet sludges sampled from four South African and Zimbabwean water treatment plants, and decreasing upon drying and processing. There was no culturable pathogenic (fecal coliforms, enterococci, Salmonella and Shigella) regrowth in soil incubations amended with dry WTR. However, the competition (microbial load and diversity) introduced by a WTR co-amendment did not limit pathogen survival in soils amended with biosolids. The application of WTR to nutrient-poor sandy soils for wheat (Triticum aestivum L.) growth improved the prokaryotic and eukaryotic culturable cell concentrations, similar to compost. However, the compost microbiome more significantly impacted the bacterial beta diversity of the receiving soil than WTR, analyzed with ARISA. Thus, although there was a low pathogen risk for WTR-amendment in receiving soils, and total soil microbial loads were increased, microbial diversity was more significantly enhanced by compost than WTR
Diagnostic accuracy of magnetic resonance imaging for nerve injury in obstetric brachial plexus injury: protocol for systematic review and meta-analysis
Background
Early and accurate clinical diagnosis of the extent of obstetric brachial plexus injury (OBPI) is challenging. The current gold standard for delineating the nerve injury is surgical exploration, and synchronous reconstruction is performed if indicated. Magnetic resonance imaging (MRI) is a non-invasive method of assessing the anatomy and severity of nerve injury in OBPI but the diagnostic accuracy is unclear.
The primary objective of this review is to determine the diagnostic accuracy of MRI in comparison to surgical brachial plexus exploration for detecting root avulsion in children under 5 with OBPI. The secondary objectives are to determine its’ diagnostic accuracy for detecting nerve abnormality and detecting pseudomeningocele(s) in this group.
Methods
This review will be conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA).We will include studies reporting the accuracy of MRI (index test) compared to surgical exploration (reference standard) in detecting any of the three target conditions (root avulsion, any nerve abnormality and pseudomeningocele) in children under five with OBPI. Case reports and studies where the number of true positives, false positives, true negatives and false negatives cannot be derived will be excluded. We plan to search PubMed, Embase and CENTRAL for relevant studies from database inception to 15 June 2022. We will also search grey literature (medRxiv, bioRxiv and Google Scholar) and perform forward and backward citation chasing. Screening and full-text assessment of eligibility will be conducted by two independent reviewers, who will then both extract the relevant data. The QUADAS-2 tool will be used to assess methodological quality and risk of bias of included studies by two reviewers independently. The following test characteristics for the target conditions will be extracted: true positives, false positives, true negatives and false negatives. Estimates of sensitivity and specificity with 95% confidence intervals will be shown in forest plots for each study. If appropriate, summary sensitivities and specificities for target conditions will be obtained via meta-analyses using a bivariate model.
Discussion
This study will aim to clarify the diagnostic accuracy of MRI for detecting nerve injury in OBPI and define its clinical role.
Systematic review registration
PROSPERO CRD42021267629
The impact of changes in COVID‐19 lockdown restrictions on alcohol consumption and drinking occasion characteristics in Scotland and England in 2020 : an interrupted time‐series analysis
Background and Aims
Early evidence suggests that COVID-19 lockdown restrictions affect alcohol consumption. However, existing studies lack data on how drinking practices changed as restrictions disrupted people’s work, family life and socializing routines. We examined changes in consumption and drinking occasion characteristics during three periods of changing restrictions in Scotland/England.
Design
Interrupted time-series analysis of repeat cross-sectional market research data (assessing step-level changes).
Setting
Scotland/England, January 2009–December 2020.
Participants
Scotland: 41 507 adult drinkers; England: 253 148 adult drinkers.
Measurements
Three intervention points: March 2020 lockdown, July 2020 easing of restrictions and October 2020 re-introduction of some restrictions. Primary outcome: mean units consumed per week (total/off-trade/on-trade; 1 unit = 8 g ethanol). Secondary outcomes: drinking > 14 units per week, heavy drinking, drinking days per week, solitary drinking, drinking with family/partners, drinking with friends/colleagues, own-home drinking, drinking in someone else’s home and drinking start times.
Findings
In Scotland, March 2020’s lockdown was associated with a 2.32 [95% confidence interval (CI) = 0.61, 4.02] increase in off-trade (i.e. shop-bought) units per week, a −2.84 (95% CI = −3.63, −2.06) decrease in on-trade (i.e. licensed venues) units per week, but no statistically significant change in total units per week. July 2020’s easing of restrictions was associated with a 1.33 (95% CI = 0.05, 2.62) increase in on-trade units per week, but no statistically significant total/off-trade consumption changes. October 2020’s re-introduction of some restrictions was not associated with statistically significant consumption changes. Results for England were broadly similar. Lockdown restrictions were also associated with later drinking start times, fewer occasions in someone else’s home and with friends/colleagues, more own-home drinking and (in Scotland only) more solitary drinking.
Conclusions
Reductions in on-trade alcohol consumption following COVID-19 lockdown restrictions in Scotland/England in 2020 were mainly offset by increased own-home drinking. This largely persisted in periods of greater/lesser restrictions. The shift towards off-trade drinking involved significant changes in the characteristics of drinking occasions
AMPK is essential for energy homeostasis regulation and glucose sensing by POMC and AgRP neurons
Hypothalamic AMP-activated protein kinase (AMPK) has been suggested to act as a key sensing mechanism, responding to hormones and nutrients in the regulation of energy homeostasis. However, the precise neuronal populations and cellular mechanisms involved are unclear. The effects of long-term manipulation of hypothalamic AMPK on energy balance are also unknown. To directly address such issues, we generated POMC alpha 2KO and AgRP alpha 2KO mice lacking AMPK alpha 2 in proopiomelanocortin- (POMC-) and agouti-related protein-expressing (AgRP-expressing) neurons, key regulators of energy homeostasis. POMC alpha 2KO mice developed obesity due to reduced energy expenditure and dysregulated food intake but remained sensitive to leptin. in contrast, AgRPa2KO mice developed an age-dependent lean phenotype with increased sensitivity to a melanocortin agonist. Electrophysiological studies in AMPK alpha 2-deficient POMC or AgRP neurons revealed normal leptin or insulin action but absent responses to alterations in extracellular glucose levels, showing that glucose-sensing signaling mechanisms in these neurons are distinct from those pathways utilized by leptin or insulin. Taken together with the divergent phenotypes of POMC alpha 2KO and AgRP alpha 2KO mice, our findings suggest that while AMPK plays a key role in hypothalamic function, it does not act as a general sensor and integrator of energy homeostasis in the mediobasal hypothalamus
Adenosine-mono-phosphate-activated protein kinase-independent effects of metformin in T cells
The anti-diabetic drug metformin regulates T-cell responses to immune activation and is proposed to function by regulating the energy-stress-sensing adenosine-monophosphate-activated protein kinase (AMPK). However, the molecular details of how metformin controls T cell immune responses have not been studied nor is there any direct evidence that metformin acts on T cells via AMPK. Here, we report that metformin regulates cell growth and proliferation of antigen-activated T cells by modulating the metabolic reprogramming that is required for effector T cell differentiation. Metformin thus inhibits the mammalian target of rapamycin complex I signalling pathway and prevents the expression of the transcription factors c-Myc and hypoxia-inducible factor 1 alpha. However, the inhibitory effects of metformin on T cells did not depend on the expression of AMPK in T cells. Accordingly, experiments with metformin inform about the importance of metabolic reprogramming for T cell immune responses but do not inform about the importance of AMPK
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