Dark matter heats up in dwarf galaxies Read, J I; Walker, M G; Steger, P
Monthly Notices of the Royal Astronomical Society,
03/2019, Letnik:
484, Številka:
1
Journal Article
Metal oxide resistive-type nano-scale gas sensors have been investigated for their low cost, high sensitivity, and environmentally friendly fabrication. In these sensors, electrical resistance ...measurements are used to detect the presence of gas. In n-type metal oxides, resistance is increased by coverage of adsorbed oxygen and lowered by removal of adsorbed oxygen through reactions with reducing gasses. The sensitivity and selectivity of these sensors have been improved by incorporation of heterostructures. Heterostructures may improve sensor performance through facilitating catalytic activity, increasing adsorption, and creating a charge carrier depletion layer that produces a larger modulation in resistance. Synergistic effects in these gas sensors describe the improved sensor signal due to these combined effects which act to amplify the reception and transduction of the sensor signal. Receptive mechanisms may be improved by increasing adsorption and reactivity. Transduction mechanisms may be improved by restriction of the major charge conduction channels which helps to maximize resistance modulation. In this review, the synergistic effect achieved by combining these two mechanisms are examined. Fundamental properties of the metal oxide surface are used to provide insight for the large body of experimental evidence available for metal oxide resistive-type gas sensors. This review aims to connect experimental evidence to conceptual mechanistic descriptions by examining adsorption processes, charge transfer, reaction mechanisms, morphology, and ambient gas interactions.
Drastic miniaturization of electronics and ingression of next-generation nanomaterials into space technology have provoked a renaissance in interplanetary flights and near-Earth space exploration ...using small unmanned satellites and systems. As the next stage, the NASA's 2015 Nanotechnology Roadmap initiative called for new design paradigms that integrate nanotechnology and conceptually new materials to build advanced, deep-space-capable, adaptive spacecraft. This review examines the cutting edge and discusses the opportunities for integration of nanomaterials into the most advanced types of electric propulsion devices that take advantage of their unique features and boost their efficiency and service life. Finally, we propose a concept of an adaptive thruster.
Google's ‘Community Mobility Reports’ (CMR) detail changes in activity and mobility occurring in response to COVID-19. They thus offer the unique opportunity to examine the relationship between ...mobility and disease incidence. The objective was to examine whether an association between COVID-19-confirmed case numbers and levels of mobility was apparent, and if so then to examine whether such data enhance disease modelling and prediction. CMR data for countries worldwide were cross-correlated with corresponding COVID-19-confirmed case numbers. Models were fitted to explain case numbers of each country's epidemic. Models using numerical date, contemporaneous and distributed lag CMR data were contrasted using Bayesian Information Criteria. Noticeable were negative correlations between CMR data and case incidence for prominent industrialised countries of Western Europe and the North Americas. Continent-wide examination found a negative correlation for all continents with the exception of South America. When modelling, CMR-expanded models proved superior to the model without CMR. The predictions made with the distributed lag model significantly outperformed all other models. The observed relationship between CMR data and case incidence, and its ability to enhance model quality and prediction suggests data related to community mobility could prove of use in future COVID-19 modelling.
The case for a cold dark matter cusp in Draco Read, J I; Walker, M G; Steger, P
Monthly Notices of the Royal Astronomical Society,
11/2018, Letnik:
481, Številka:
1
Journal Article
Summary
Background
Study of the upper gastrointestinal microbiome has shown that other bacteria besides Helicobacter pylori flourish despite the hostile environment. Whilst H. pylori is the most ...studied bacteria in this region with a defined role in inflammation and neoplasia, it is apparent that other bacteria may contribute to UGI disease.
Aim
To review current knowledge of bacteria inhabiting the oesophagus, stomach and duodenum.
Methods
Published studies on the upper gastrointestinal microbiome (extracted from PubMed during the last 20 years).
Results
The stomach is a hostile environment for bacteria; however, recent studies categorising the microbiota have shown surprising results. Helicobacter pylori has been intensively studied since 1984 and recent sequencing analysis of other gastric microbiota shows that H. pylori is not alone. Composition can be influenced by acid suppression, gastritis and abundance of H. pylori. Eradication of H. pylori, whilst decreasing gastric cancer is associated with an increase in asthma, reflux and obesity. A future approach may be to selectively eradicate bacteria which predispose to inflammation and cancer as opposed to a comprehensive knockout policy. In the oesophagus, viridans streptococci are the most common bacteria influenced by both oral and gastric bacteria. Oesophagitis and Barrett's oesophagus are characterised by a significant decrease in Gram‐positive bacteria and an increase in Gram‐negative bacteria. An inverse association of H. pylori and oesophageal adenocarcinoma is described. The duodenal microbiome has been shown to influence small intestinal bacterial overgrowth, irritable bowel syndrome and coeliac disease. The numbers of bacteria recoverable by culture are variable in the stomach mucosa and gastric juice, typically 102–104 colony‐forming units (CFU)/g or mL and in the oesophagus, up to 104 bacteria per mm2 mucosal surface. In the small bowel, in health, 103 CFU/mL are normal.
Conclusion
This review highlights current knowledge of upper gastrointestinal bacteria and associations with disease.
Environmental mercury and its toxic effects Rice, Kevin M; Walker, Jr, Ernest M; Wu, Miaozong ...
Journal of preventive medicine and public health,
03/2014, Letnik:
47, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Mercury exists naturally and as a man-made contaminant. The release of processed mercury can lead to a progressive increase in the amount of atmospheric mercury, which enters the ...atmospheric-soil-water distribution cycles where it can remain in circulation for years. Mercury poisoning is the result of exposure to mercury or mercury compounds resulting in various toxic effects depend on its chemical form and route of exposure. The major route of human exposure to methylmercury (MeHg) is largely through eating contaminated fish, seafood, and wildlife which have been exposed to mercury through ingestion of contaminated lower organisms. MeHg toxicity is associated with nervous system damage in adults and impaired neurological development in infants and children. Ingested mercury may undergo bioaccumulation leading to progressive increases in body burdens. This review addresses the systemic pathophysiology of individual organ systems associated with mercury poisoning. Mercury has profound cellular, cardiovascular, hematological, pulmonary, renal, immunological, neurological, endocrine, reproductive, and embryonic toxicological effects.
Purpose
The EUPHRATES trial examined the impact of polymyxin B hemoperfusion (PMX) on mortality in patients with septic shock and endotoxemia, defined as EAA ≥ 0.60. No difference was found in 28-day ...all-cause mortality. However, the trial showed that in some patients with septic shock the burden of endotoxin activity was extreme (EAA ≥ 0.9). In a post hoc analysis, we evaluated the impact of PMX use in patients with septic shock and endotoxin activity measured between 0.6–0.89.
Methods
Post-hoc analysis of the EUPHRATES trial for the 194 patients with EAA ≥ 0.6–0.89 who completed two treatments (PMX or sham). The primary end point was mortality at 28 days adjusted for APACHE II score and baseline mean arterial pressure (MAP). Additional end points included changes in MAP, cumulative vasopressor index (CVI), median EAA reduction, ventilator-free days (VFD), dialysis-free days (DFD) and hospital length of stay. Subpopulations analyzed were site and type of infection and those with norepinephrine dose > 0.1 mcg/kg/min at baseline.
Results
At 28 days, 23 patients of 88 (26.1%) in the PMX group died versus 39 of 106 (36.8%) in the sham group risk difference 10.7%, OR 0.52, 95% CI (0.27, 0.99),
P
= 0.047. When unadjusted for baseline variables,
P
= 0.11. The 28-day survival time in the PMX group was longer than for the sham group HR 0.56 (95% CI 0.33, 0.95)
P
= 0.03. PMX treatment compared with sham showed greater change in MAP median (IQR) 8 mmHg (− 0.5, 19.5) vs. 4 mmHg (− 4.0, 11)
P
= 0.04 and VFD median (IQR) 20 days (0.5, 23.5) vs. 6 days (0, 20),
P
= 0.004. There were no significant differences in other end points. There was a significant difference in mortality in PMX-treated patients with no bacterial growth on culture PMX, 6/30 (20%) vs. sham, 13/31 (41.9%),
P
= 0.005. The median EAA change in the population was − 12.9% (range: increase 49.2%–reduction 86.3%). The mortality in the above median EAA change group was PMX: 6/38 (15.7%) vs. sham 15/49 (30.6%),
P
= 0.08.
Conclusions
These hypothesis-generating results, based on an exploratory post hoc analysis of the EUPHRATES trial, suggest measurable responses in patients with septic shock and an EAA ≥ 0.6 to 0.89 on changes in mean arterial pressure, ventilator-free days and mortality.
Trial registration
Clinicaltrials.gov Identifier: NCT01046669. Funding Spectral Medical Incorporated.
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