2,372 research outputs found
Intercomparisons of high-resolution solar blind Raman lidar atmospheric profiles of water vapor with radiosondes and kytoon
A report is given of measurements of atmospheric profiles of water vapor in the boundary layer by use of solar blind Raman lidar. These measurement episodes, occuring twice a day over a two week period, were accompanied by a dense net of supporting measurements. The support included two radiosonde launches per measurement episodes as well as a kytoon support measurement of water vapor using a wet bulb-dry bulb instrument. The kytoon strategy included ten minute stops at strategic altitudes. Additional kytoon measurements included ozone profiles and nephelometric extinction profiles in the visible. Typically, six or seven 1000 shot lidar profile averages were collected during a measurement episode. Overall performance comparisons are provided and intercomparisons between auxiliary measurement devices are presented. Data on the accuracy of the lidar water vapor profiles are presented
Moderate exercise increases affinity of large very low density lipoproteins for hydrolysis by lipoprotein lipase
Context:
Postprandial triglyceride (TG) concentration is independently associated with cardiovascular disease risk. Exercise reduces postprandial TG concentrations but the mechanisms responsible are unclear.
Objective:
To determine the effects of exercise on affinity of chylomicrons, large very low density lipoproteins (VLDL1) and smaller VLDL (VLDL2) for lipoprotein lipase (LPL) mediated TG hydrolysis.
Design:
Within-participant cross-over study.
Setting:
A University metabolic investigation unit.
Participants:
Ten overweight/obese men.
Interventions:
Participants undertook two oral fat tolerance tests, separated by 7–14 days, in which they had blood taken fasting and for 4 hours after a high-fat mixed meal. On the afternoon before one test, they performed a 90-minute treadmill walk at 50% maximal oxygen uptake (EX); no exercise was performed before the control test (CON).
Main outcome measures:
Circulating TG-rich lipoprotein concentrations; affinity of chylomicrons, VLDL1, VLDL2 for LPL-mediated TG hydrolysis.
Results:
Exercise significantly reduced fasting VLDL1-TG concentration (CON: 0.49(0.33–0.72) mmol.l−1, EX: 0.36(0.22–0.59) mmol.l−1, [geometric means (95% confidence interval)]; p=0.04). Time-averaged postprandial chylomicron-TG (CON: 0.55±0.10 mmol.l−1, EX: 0.39±0.08 mmol.l−1, [mean±SEM], p=0.03) and VLDL1-TG (CON: 0.85±0.13 mmol.l−1, EX: 0.66±0.10 mmol.l−1, p=0.01) concentrations were both lower in EX than CON. Affinity of VLDL1 for LPL-mediated TG hydrolysis increased by 2.2(1.3–3.7) fold (geometric mean (95% confidence interval)) (p=0.02) in the fasted state and 2.6(1.8–2.6) fold (p=0.001) postprandially. Affinity of chylomicrons and VLDL2 was not significantly different between trials.
Conclusions:
Exercise increases affinity of VLDL1 for LPL-mediated TG hydrolysis both fasting and postprandially. This mechanism is likely to contribute to exercise's TG-lowering effect
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Nursing teamwork in the care of older people: A mixed methods study
Healthcare is increasingly complex and requires the ability to adapt to changing demands. Teamwork is essential
to delivering high quality care and is central to nursing. The aims of this study were to identify the processes that
underpin nursing teamwork and how these affect the care of older people, identify the relationship between
perceived teamwork and perceived quality of care, and explore in depth the experience of working in nursing
teams. The study was carried out in three older people's wards in a London teaching hospital. Nurses and
healthcare assistants completed questionnaires (n=65) on known dynamics of teamwork (using the Nursing
Teamwork Survey) together with ratings of organisational quality (using an adapted AHRQ HSPS scale). A
sample (n=22; 34%) was then interviewed about their perceptions of care, teamwork and how good outcomes
are delivered in everyday work. Results showed that many care difficulties were routinely encountered, and
confirmed the importance of teamwork (e.g. shared mental models of tasks and team roles and responsibilities,
supported by leadership) in adapting to challenges. Perceived quality of teamwork was positively related to
perceived quality of care. Work system variability and the external environment influenced teamwork, and
confirmed the importance of team adaptive capacity. The CARE model shows the centrality of teamwork in
adapting to variable demand and capacity to deliver care processes, and the influence of broader system factors
on teamworking
Thermal analysis of some environmentally degradable polymers
The thermal characteristics of a series of degradable polymers have been investigated using thermogravimetry and differential scanning calorimetry. While the results of the thermogravimetry experiments suggest that the thermal stability of the polymers should not pose any problems at the temperatures that can be expected in a commercial composting process (60\ub0C), phase changes associated with some of the polymers investigated may cause problems in the interpretation of data from composting degradation studies. Several biodegradable polymers were observed to have melt transitions at temperatures similar to those found in a compositing environment. Consequently, under the controlled composting conditions used to evaluate biodegradable polymers, degradation of a polymer may be inferred, while actually the polymer has merely undergone a phase change.Peer reviewed: YesNRC publication: Ye
Analysis of the rotation period of asteroids (1865) Cerberus, (2100) Ra-Shalom, and (3103) Eger - search for the YORP effect
The spin state of small asteroids can change on a long timescale by the
Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, the net torque that arises
from anisotropically scattered sunlight and proper thermal radiation from an
irregularly-shaped asteroid. The secular change in the rotation period caused
by the YORP effect can be detected by analysis of asteroid photometric
lightcurves. We analyzed photometric lightcurves of near-Earth asteroids (1865)
Cerberus, (2100) Ra-Shalom, and (3103) Eger with the aim to detect possible
deviations from the constant rotation caused by the YORP effect. We carried out
new photometric observations of the three asteroids, combined the new
lightcurves with archived data, and used the lightcurve inversion method to
model the asteroid shape, pole direction, and rotation rate. The YORP effect
was modeled as a linear change in the rotation rate in time d\omega /dt. Values
of d\omega/ dt derived from observations were compared with the values
predicted by theory. We derived physical models for all three asteroids. We had
to model Eger as a nonconvex body because the convex model failed to fit the
lightcurves observed at high phase angles. We probably detected the
acceleration of the rotation rate of Eger d\omega / dt = (1.4 +/- 0.6) x
10^{-8} rad/d (3\sigma error), which corresponds to a decrease in the rotation
period by 4.2 ms/yr. The photometry of Cerberus and Ra-Shalom was consistent
with a constant-period model, and no secular change in the spin rate was
detected. We could only constrain maximum values of |d\omega / dt| < 8 x
10^{-9} rad/d for Cerberus, and |d\omega / dt| < 3 x 10^{-8} rad/d for
Ra-Shalom
Two approaches to testing general relativity in the strong-field regime
Observations of compact objects in the electromagnetic spectrum and the
detection of gravitational waves from them can lead to quantitative tests of
the theory of general relativity in the strong-field regime following two very
different approaches. In the first approach, the general relativistic field
equations are modified at a fundamental level and the magnitudes of the
potential deviations are constrained by comparison with observations. In the
second approach, the exterior spacetimes of compact objects are parametrized in
a phenomenological way, the various parameters are measured observationally,
and the results are finally compared against the general relativistic
predictions. In this article, I discuss the current status of both approaches,
focusing on the lessons learned from a large number of recent investigations.Comment: To appear in the proceedings of the conference New Developments in
Gravit
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