5,305 research outputs found
Inelastic collision processes in ozone and their relation to atmospheric pressure broadening
The research task employs infrared double-resonance to determine rotational energy transfer rates and pathways, in both the ground and vibrationally excited states of ozone. The resulting data base will then be employed to test inelastic scattering theories and to assess intermolecular potential models, both of which are necessary for the systematization and prediction of infrared pressure-broadening coefficients, which are in turn required by atmospheric ozone monitoring techniques based on infrared remote sensing. In addition, observation of excited-state absorption transitions will permit us to improve the determination of the 2 nu(sub 3), nu(sub 1) + nu(sub 2), and 2 nu(sub 1) rotational constants and to derive band strengths for hot-band transitions involving these levels
The informational advantage of specialized monitors: the case of bank examiners
Large commercial banking firms are monitored by specialized private sector monitors and by specialized government examiners. Previous research suggests that bank exams produce little useful information that is not already reflected in market prices. In this article, we apply a new research methodology to a unique data set, and find that government exams of large national banks produce significant new information which financial markets do not fully internalize for several additional months. Our results indicate that specialized government monitors can identify value-relevant information about private firms, even if those firms are already actively followed by investors and their private-sector agents.Bank supervision ; Bank examination
Market evidence on the opaqueness of banking firms' assets.
We assess the market microstructure properties of U.S. banking firms' equity, to determine whether they exhibit more or less evidence of asset opaqueness than similar-sized nonbanking firms. The evidence strongly indicates that large banks (traded on NASDAQ) trade much less frequently despite microstructure characteristics. Problem (noncurrent) loans tend to raise the frequency with which the bank's equity trades, as well as the equity's return volatility. The implications for regulatory policy and future market microstructure research are discussed.Bank stocks ; Bank assets
Environment assisted electron capture
Electron capture by {\it isolated} atoms and ions proceeds by
photorecombination. In this process a species captures a free electron by
emitting a photon which carries away the excess energy. It is shown here that
in the presence of an {\it environment} a competing non-radiative electron
capture process can take place due to long range electron correlation. In this
interatomic (intermolecular) process the excess energy is transferred to
neighboring species. The asymptotic expression for the cross section of this
process is derived. We demonstrate by explicit examples that under realizable
conditions the cross section of this interatomic process can clearly dominate
that of photorecombination
Plasma Physics
Contains reports on three research projects.U. S. Atomic Energy Commission (Contract AT(30-1)-1842
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Effectiveness of physical activity interventions for overweight and obesity during pregnancy: a systematic review of the content of behaviour change interventions
Background
Behaviour change techniques (BCTs) employed within PA intervention for pregnant women with a healthy body mass index (BMI) have been previously identified, however, these BCTS may differ for other weight profiles during pregnancy. The aim of this current review was to identify and summarise the evidence for effectiveness of PA interventions on PA levels for pregnant women with overweight and obesity, with an emphasis on the BCTs employed.
Methods
A systematic review and meta-analysis of PA intervention studies using the PRISMA statement was conducted. Searches were conducted of eight databases in January 2019. Strict inclusion/exclusion criteria were employed. The validity of each included study was assessed using the Cochrane Collaboration’s tool for assessing risk of bias. The primary outcome measure was change in PA levels, subjectively or objectively measured, with physical fitness as a secondary outcome. All intervention descriptions were double coded by two authors using Michie’s et al’s BCT taxonomy V1. Meta-analyses using random effect models assessed the intervention effects on PA. Other PA outcomes were summarised in a narrative synthesis.
Results
From 8389 studies, 19 met the inclusion criteria 13 of which were suitable for inclusion in a meta-analysis. The remaining 6 studies were described narratively due to insufficient data and different outcome measures reported. In the meta-analysis, comparing interventions to a control group, significant increases were found in the intervention group for metabolic equivalent (SMD 0.39 [0.14, 0.64], Z = 3.08 P = 0.002) and physical fitness (VO2 max) (SMD 0.55 [0.34, 0.75], Z = 5.20 P = < 0.001). Of the other six, five studies reported an increase in PA for the intervention group versus the control with the other study reporting a significant decrease for women in their 3rd trimester (p = 0.002). ‘Self-monitoring of behaviour’ was the most frequently used BCTs (76.5%), with ‘social support’ being newly identified for this pregnant population with overweight or obesity.
Conclusions
This review identified a slight increase in PA for pregnant women with overweight and obesity participating in interventions. However, due to the high risk of bias of the included studies, the results should be interpreted with caution. PA measures should be carefully selected so that studies can be meaningfully compared and standardised taxonomies should be used so that BCTs can be accurately assessed
Coronal activity cycles in nearby G and K stars - XMM-Newton monitoring of 61 Cygni and Alpha Centauri
We use X-ray observations of the nearby binaries 61 Cyg A/B (K5V and K7V) and
Alpha Cen A/B (G2V and K1V) to study the long-term evolution of magnetic
activity in weakly to moderately active G + K dwarfs over nearly a decade.
Specifically we search for X-ray activity cycles and related coronal changes
and compare them to the solar behavior. For 61 Cyg A we find a regular coronal
activity cycle analog to its 7.3 yr chromospheric cycle. The X-ray brightness
variations are with a factor of three significantly lower than on the Sun, yet
the changes of coronal properties resemble the solar behavior with larger
variations occurring in the respective hotter plasma components. 61 Cyg B does
not show a clear cyclic coronal trend so far, but the X-ray data matches the
more irregular chromospheric cycle. Both Alpha Cen stars exhibit significant
long-term X-ray variability. Alpha Cen A shows indications for cyclic
variability of an order of magnitude with a period of about 12-15 years; the
Alpha Cen B data suggests an X-ray cycle with an amplitude of about six to
eight and a period of 8-9 years. The sample stars exhibit X-ray luminosities
ranging between Lx < 1x10^26 - 3x10^27 erg s^-1 in the 0.2-2.0 keV band and
have coronae dominated by cool plasma with variable average temperatures of
around 1.0-2.5 MK. We find that coronal activity cycles are apparently a common
phenomenon in older, slowly rotating G and K stars. The spectral changes of the
coronal X-ray emission over the cycles are solar-like in all studied targets.Comment: 11 pages, 9 figures, accepted by Astronomy and Astrophysic
Circinus X-1: survivor of a highly asymmetric supernova
We have analyzed the kinematical parameters of Cir X-1 to constrain the
nature of its companion star, the eccentricity of the binary and the
pre-supernova parameter space. We argue that the companion is most likely to be
a low-mass (< 2.0 M_sun) unevolved star and that the eccentricity of the orbit
is 0.94 +/- 0.04. We have evaluated the dynamical effects of the supernova
explosion and we find it must have been asymmetric. On average, we find that a
kick of 740 km/s is needed to account for the recently measured radial velocity
of +430 km/s (Johnston, Fender & Wu) for this extreme system. The corresponding
minimum kick velocity is 500 km/s. This is the largest kick needed to explain
the motion of any observed binary system. If Cir X-1 is associated with the
supernova remnant G321.9-0.3 then we find a limiting minimum age of this
remnant of 60000 yr. Furthermore, we predict that the companion star has lost
10% of its mass as a result of stripping and ablation from the impact of the
supernova shell shortly after the explosion.Comment: 6 pages, 3 figues, 2 tables, accepted for publication in MNRA
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