5,319 research outputs found
A massive reservoir of low-excitation molecular gas at high redshift
Molecular hydrogen is an important component of galaxies because it fuels
star formation and accretion onto AGN, the two processes that generate the
large infrared luminosities of gas-rich galaxies. Observations of spectral-line
emission from the tracer molecule CO are used to probe the properties of this
gas. But the lines that have been studied in the local Universe, mostly the
lower rotational transitions of J = 1-0 and J = 2-1, have hitherto been
unobservable in high-redshift galaxies. Instead, higher transitions have been
used, although the densities and temperatures required to excite these higher
transitions may not be reached by much of the gas. As a result, past
observations may have underestimated the total amount of molecular gas by a
substantial amount. Here we report the discovery of large amounts of
low-excitation molecular gas around the infrared-luminous quasar, APM
08279+5255 at z = 3.91, using the two lowest excitation lines of 12CO (J = 1-0
and J = 2-1). The maps confirm the presence of hot and dense gas near the
nucleus, and reveal an extended reservoir of molecular gas with low excitation
that is 10 to 100 times more massive than the gas traced by higher-excitation
observations. This raises the possibility that significant amounts of
low-excitation molecular gas may lurk in the environments of high-redshift (z >
3) galaxies.Comment: To appear as a Letter to Nature, 4th January 200
The detection and sensory perception of inspiratory resistive loads in people with chronic tetraplegia
This study investigated sensations of breathing following tetraplegia. Fifteen people with chronic tetraplegia and fifteen healthy able-bodied controls matched for age, sex, height, and weight participated. Sensations of breathing were quantified by determining the threshold for detecting an added resistance during inspiration. In a separate task, the perceived magnitudes of six suprathreshold resistive loads were determined with a modified Borg scale. The detection threshold of 0.34 cmH2O/L/s [standard deviation (SD) 0.14] in the tetraplegia group was higher than the 0.23 cmH2O/L/s (SD 0.10) threshold for able-bodied controls (P = 0.004). Both participant groups perceived larger loads to be more effortful, with the Borg effort rating increasing linearly with the peak inspiratory pressure generated at each load. The relationship between Borg effort rating and peak inspiratory pressure was steeper in participants with tetraplegia than in able-bodied controls (P = 0.001), but there was no difference when pressure was divided by maximal inspiratory pressure (P = 0.95). Despite a higher detection threshold, the findings suggest that the perceived magnitude of a suprathreshold inspiratory load is not impaired in chronic tetraplegia and that load magnitude perception is related to the maximal, and not absolute, inspiratory muscle force. NEW & NOTEWORTHY Sensations of breathing are thought to be impaired following chronic tetraplegia. The detection threshold for an added resistive load during inspiration was higher in people with tetraplegia than in healthy able-bodied participants. However, for inspiratory loads above the detection threshold, the perceived magnitude of a resistive load as a function of the peak inspiratory pressure was greater in tetraplegia. Load magnitude perception was comparable between participant groups when peak pressure was divided by maximal inspiratory pressure
The reliability of inspiratory resistive load magnitude and detection testing
Objectives: To assess the test-retest reliability of inspiratory load detection and load magnitude perception tests in healthy volunteers. Design: Cohort of convenience. Setting: Respiratory physiology laboratory. Participants: Twenty healthy adults. Interventions: On two separate occasions participants performed tests of inspiratory loading. Participants breathed through custom made resistive tubing and were asked to indicate when they detected a different resistance during inspiration. In a second test participants rated the magnitude of presented inspiratory loads using the modified Borg score. Main Outcome Measures: Intra-class Correlation Coefficient (ICC2,1) values for repeated tests of inspiratory load detection threshold and load magnitude rating. Results: ICC2,1 values ranged from 0.657–0.786 for load detection testing and 0.739 to 0.969 for rating of load magnitude. Conclusions: The tests are simple and reliable measures of inspiratory load detection and magnitude rating. They can be used in future research to determine the effectiveness of interventions to reduce the effort of breathing in health and disease
Effect of microplastic on the gills of the Shore Crab Carcinus maenas
This is a “Just Accepted” manuscript. "Just Accepted manuscripts" have been peer-reviewed and accepted for publication. They are posted
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or consequences arising from the use of information contained in these “Just Accepted” manuscripts.Microscopic plastic debris (microplastics, <5mm in diameter) is ubiquitous in the marine environment. Previous work has shown that microplastics may be ingested and inhaled by the shore crab Carcinus maenas although the biological consequences are unknown. Here, we show that acute aqueous exposure to polystyrene microspheres (8μm) with different surface coatings had significant but transient effects on branchial function. Microspheres inhaled into the gill chamber had a small but significant dose dependent effect on oxygen consumption after 1 hour of exposure, returning to normal levels after 16 h. Ion exchange was also affected, with a small but significant decrease in hemolymph sodium ions and an increase in calcium ions after 24 h post exposure. To further asses the effects on osmoregulation, crabs were challenged with reduced salinity after microplastic exposure. Neither microspheres nor natural sediments altered the crab’s response to osmotic stress, regardless of plastic concentration added. Carboxylated (COOH) and aminated (NH2) polystyrene microspheres were distributed differently across the gill surface, although neither had a significant adverse impact on gill function. These results illustrate the extent of the physiological effects of microplastics, compared to the physiological resilience of shore crabs in maintaining osmoregulatory and respiratory function after acute exposure to both anthropogenic plastics and natural particles.W, CL and TG acknowledge funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 308370. The contents of this publication are the responsibility of the CleanSea project and can in no way be taken to reflect the views of the European Union. TG and CL acknowledge additional support from NERC NE/L007010/1
Impact of respiratory muscle training on respiratory muscle strength, respiratory function and quality of life in individuals with tetraplegia: A randomised clinical trial
Background Respiratory complications remain a leading cause of morbidity and mortality in people with acute and chronic tetraplegia. Respiratory muscle weakness following spinal cord injury-induced tetraplegia impairs lung function and the ability to cough. In particular, inspiratory muscle strength has been identified as the best predictor of the likelihood of developing pneumonia in individuals with tetraplegia. We hypothesised that 6 weeks of progressive respiratory muscle training (RMT) increases respiratory muscle strength with improvements in lung function, quality of life and respiratory health. Methods Sixty-two adults with tetraplegia participated in a double-blind randomised controlled trial. Active or sham RMT was performed twice daily for 6 weeks. Inspiratory muscle strength, measured as maximal inspiratory pressure (PImax) was the primary outcome. Secondary outcomes included lung function, quality of life and respiratory health. Between-group comparisons were obtained with linear models adjusting for baseline values of the outcomes. Results After 6 weeks, there was a greater improvement in PImax in the active group than in the sham group (mean difference 11.5 cmH 2 O (95% CI 5.6 to 17.4), p<0.001) and respiratory symptoms were reduced (St George Respiratory Questionnaire mean difference 10.3 points (0.01-20.65), p=0.046). Significant improvements were observed in quality of life (EuroQol-Five Dimensional Visual Analogue Scale 14.9 points (1.9-27.9), p=0.023) and perceived breathlessness (Borg score 0.64 (0.11-1.17), p=0.021). There were no significant improvements in other measures of respiratory function (p=0.126-0.979). Conclusions Progressive RMT increases inspiratory muscle strength in people with tetraplegia, by a magnitude which is likely to be clinically significant. Measurement of baseline PImax and provision of RMT to at-risk individuals may reduce respiratory complications after tetraplegia. Trial registration number Australian New Zealand Clinical Trials Registry (ACTRN 12612000929808)
Safety, Tolerability, and Pharmacokinetics of ARC-520 Injection, an RNA Interference-Based Therapeutic for the Treatment of Chronic Hepatitis B Virus Infection, in Healthy Volunteers
published_or_final_versio
A systematic review of the discriminating biomechanical parameters during the single leg squat
Objective: To determine whether there are common biomechanical parameters when analysing the single leg squat movement to compare pathological and non-pathological groups and whether these parameters are able to effectively distinguish between groups.
Methods: Five electronic databases were searched using MESH terms, keywords and phrases across four constructs: squat, biomechanical measures, region of interest, study design. Studies were selected based on inclusion of a quantitative biomechanical measure, compared between a pathological and a non-pathological group, and participants performed a single leg squat movement.
Results: Fifteen studies were included and reviewed, where the majority of studies investigated patellofemoral pain. There was considerable variation in the biomechanical outcome measure used to compare between groups. The frontal plane projection angle was the most commonly reported measure. There was considerable variation in the manner in which the single leg squat was performed.
Conclusion: Due to variation in how the single leg squat was performed, it was not possible to determine specific biomechanical parameters that distinguish between pathological and non-pathological groups. Frontal plane projection angle appeared to be a parameter that could be effectively utilised. Standardisation of the single leg squat movement is needed to allow comparison between studies of pathological and non-pathological groups
Measurement properties of quality of life measurement instruments for infants, children and adolescents with eczema: protocol for a systematic review
Background: Eczema is a common chronic or chronically relapsing skin disease that has a substantial impact on quality of life (QoL). By means of a consensus-based process, the Harmonising Outcome Measures in Eczema (HOME) initiative has identified QoL as one of the four core outcome domains to be assessed in all eczema trials. Few measurement instruments exist to measure QoL in infants and children with eczema, but there is a great variability in both content and quality (for example, reliability and validity) of the instruments used, and it is not always clear if the best instrument is being used. Therefore, the aim of the proposed research is a comprehensive systematic assessment of the measurement properties of the existing measurement instruments that were developed and/or validated for the measurement of patient-reported QoL in infants and children with eczema. Methods/Design: This study is a systematic review of the measurement properties of patient-reported measures of QoL developed and/or validated for infants and children with eczema. Medline via PubMed and EMBASE will be searched using a selection of relevant search terms. Eligible studies will be primary empirical studies evaluating, describing, or comparing measurement properties of QoL instruments for infants and children with eczema. Eligibility assessment and data abstraction will be performed independently by two reviewers. Evidence tables will be generated for study characteristics, instrument characteristics, measurement properties, and interpretability. The adequacy of the measurement properties will be assessed using predefined criteria. Methodological quality of studies will be assessed using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. A best evidence synthesis will be undertaken if more than one study has investigated a particular measurement property. Discussion: The proposed systematic review will produce a comprehensive assessment of measurement properties of existing QoL instruments in infants and children with eczema. We aim to identify one best currently available instrument to measure QoL in infants and/or children with eczema
Dimensions of Children's Health Beliefs
Health beliefs interviews were conducted with 250 children aged 6-17 years. A factor analysis of the items resulted in six correlated fac tors which were interpreted as 1) specific health concerns, 2)general health concerns, 3) perceived parental concern, 4) perceived general susceptibility, 5) perceived susceptibility to specific conditions, and 6) perceived seriousness of and susceptibility to disease. Factor scores were computed and two-way analyses of variance (by age and sex of child) were conducted on six sets of factor scores. No significant sex differences or sex by age in teraction effects were noted. Younger children scored significantly higher on "specific health concerns"and "perceived general susceptibility,"while older children scored significantly higher on "perceived parental concern. " Tests of differences among variances showed a tendency for the variability to be greater among younger children. The results are interpreted as pro viding partial support for a model of children's health beliefs and as a basis for further operationalization of concepts which are central to an understand ing of motivated health behavior. Implications for practice are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66657/2/10.1177_109019818000700304.pd
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