1,551 research outputs found
Anxiety and depression in young and middle aged hypertensive and normotensive subjects
This study examined the effects of essential hypertension on measures of anxiety and depression for two age groups of hypertensive (free from hypertension-related pathology and/or cardiovascular disease) and normotensive subjects. Hypertensive subjects had significantly higher State Anxiety scores and Zung Depression scores than did normotensive subjects. These differences between the blood pressure groups were due largely to the scores of the younger hypertensive subjects. The results of the present study are consistent with previous results from our laboratory that have found that younger hypertensives differed (relative to controls) from middle aged hypertensives on measures, such as, symptoms reported on the Cornell Medical Index and WAIS Performance scores. The results of the present study were discussed within the context of age associated differences in response to hypertension and factors that might account for these differences
Relationship of age and hypertension to neuropsychological test performance
Young adult (X- = 29) and middle aged (X- =50) hypertensive and normotensive subjects were compared with respect to seven neuropsychological test scores derived from tests on the Halstead-Reitan battery. Age main effects, with inferior performance for the middle aged subjects, were observed for the localization and time portions of the Tactile Performance Test (TPT) and for the Trail Making A test. The multivariate age effect was significant for the composite of seven scores. A multivariate blood pressure main effect was obtained and main effect blood pressure was significant for the category test; hypertensives made more errors than normotensives. A blood pressure by age interaction was observed for finger tapping scores and the TPT-Memory scores with larger differences between hypertensives and normotensives for the younger than for the middle aged group. Results were discussed in terms of previous studies of age and hypertension with the WAIS, the Primary Mental Abilities Test and serial reaction time measures. The poor prediction of hypertensive status from individual neuropsychological test scores was emphasized and readers were cautioned not to conclude that essential hypertensives, as a group, can be characterized as brain damaged
Ultraviolet Imaging Polarimetry of the Large Magellanic Cloud. II. Models
Motivated by new sounding-rocket wide-field polarimetric images of the Large
Magellanic Cloud, we have used a three-dimensional Monte Carlo radiation
transfer code to investigate the escape of near-ultraviolet photons from young
stellar associations embedded within a disk of dusty material (i.e. a galaxy).
As photons propagate through the disk, they may be scattered or absorbed by
dust. Scattered photons are polarized and tracked until they escape to be
observed; absorbed photons heat the dust, which radiates isotropically in the
far-infrared, where the galaxy is optically thin. The code produces four output
images: near- UV and far-IR flux, and near-UV images in the linear Stokes
parameters Q and U. From these images we construct simulated UV polarization
maps of the LMC. We use these maps to place constraints on the star + dust
geometry of the LMC and the optical properties of its dust grains. By tuning
the model input parameters to produce maps that match the observed polarization
maps, we derive information about the inclination of the LMC disk to the plane
of the sky, and about the scattering phase function g. We compute a grid of
models with i = 28 deg., 36 deg., and 45 deg., and g = 0.64, 0.70, 0.77, 0.83,
and 0.90. The model which best reproduces the observed polarization maps has i
= 36 +2/-5 degrees and g ~0.7. Because of the low signal-to-noise in the data,
we cannot place firm constraints on the value of g. The highly inclined models
do not match the observed centro-symmetric polarization patterns around bright
OB associations, or the distribution of polarization values. Our models
approximately reproduce the observed ultraviolet photopolarimetry of the
western side of the LMC; however, the output images depend on many input
parameters and are nonunique.Comment: Accepted to AJ. 20 pages, 7 figure
Prolonged exposure of cortical neurons to oligomeric amyloid-β impairs NMDA receptor function via NADPH oxidase-mediated ROS production: protective effect of green tea (–)-epigallocatechin-3-gallate
Excessive production of Aβ (amyloid β-peptide) has been shown to play an important role in the pathogenesis of AD (Alzheimer's disease). Although not yet well understood, aggregation of Aβ is known to cause toxicity to neurons. Our recent study demonstrated the ability for oligomeric Aβ to stimulate the production of ROS (reactive oxygen species) in neurons through an NMDA (N-methyl-d-aspartate)-dependent pathway. However, whether prolonged exposure of neurons to aggregated Aβ is associated with impairment of NMDA receptor function has not been extensively investigated. In the present study, we show that prolonged exposure of primary cortical neurons to Aβ oligomers caused mitochondrial dysfunction, an attenuation of NMDA receptor-mediated Ca2+ influx and inhibition of NMDA-induced AA (arachidonic acid) release. Mitochondrial dysfunction and the decrease in NMDA receptor activity due to oligomeric Aβ are associated with an increase in ROS production. Gp91ds-tat, a specific peptide inhibitor of NADPH oxidase, and Mn(III)-tetrakis(4-benzoic acid)-porphyrin chloride, an ROS scavenger, effectively abrogated Aβ-induced ROS production. Furthermore, Aβ-induced mitochondrial dysfunction, impairment of NMDA Ca2+ influx and ROS production were prevented by pre-treatment of neurons with EGCG [(−)-epigallocatechin-3-gallate], a major polyphenolic component of green tea. Taken together, these results support a role for NADPH oxidase-mediated ROS production in the cytotoxic effects of Aβ, and demonstrate the therapeutic potential of EGCG and other dietary polyphenols in delaying onset or retarding the progression of AD
A Correlation Between Stellar Activity and Hot Jupiter Emission Spectra
We present evidence for a correlation between the observed properties of hot
Jupiter emission spectra and the activity levels of the host stars measured
using Ca II H & K emission lines. We find that planets with dayside emission
spectra that are well-described by standard 1D atmosphere models with water in
absorption (HD 189733, TrES-1, TrES-3, WASP-4) orbit chromospherically active
stars, while planets with emission spectra that are consistent with the
presence of a strong high-altitude temperature inversion and water in emission
orbit quieter stars. We estimate that active G and K stars have Lyman alpha
fluxes that are typically a factor of 4-7 times higher than quiet stars with
analogous spectral types, and propose that the increased UV flux received by
planets orbiting active stars destroys the compounds responsible for the
formation of the observed temperature inversions. In this paper we also derive
a model-independent method for differentiating between these two atmosphere
types using the secondary eclipse depths measured in the 3.6 and 4.5 micron
bands on the Spitzer Space Telescope, and argue that the observed correlation
is independent of the inverted/non-inverted paradigm for classifying hot
Jupiter atmospheres.Comment: 9 pages, 5 figures, accepted for publication in ApJ. The updated
paper includes spectra for ten additional systems and a new section
discussing the connection between chromospheric activity and UV flu
Orientation cues for high-flying nocturnal insect migrants: do turbulence-induced temperature and velocity fluctuations indicate the mean wind flow?
Migratory insects flying at high altitude at night often show a degree of common alignment, sometimes with quite small angular dispersions around the mean. The observed orientation directions are often close to the downwind direction and this would seemingly be adaptive in that large insects could add their self-propelled speed to the wind speed, thus maximising their displacement in a given time. There are increasing indications that high-altitude orientation may be maintained by some intrinsic property of the wind rather than by visual perception of relative ground movement. Therefore, we first examined whether migrating insects could deduce the mean wind direction from the turbulent fluctuations in temperature. Within the atmospheric boundary-layer, temperature records show characteristic ramp-cliff structures, and insects flying downwind would move through these ramps whilst those flying crosswind would not. However, analysis of vertical-looking radar data on the common orientations of nocturnally migrating insects in the UK produced no evidence that the migrants actually use temperature ramps as orientation cues. This suggests that insects rely on turbulent velocity
and acceleration cues, and refocuses attention on how these can be detected, especially as small-scale turbulence is usually held to be directionally invariant (isotropic). In the second part of the paper we present a theoretical analysis and simulations showing that velocity fluctuations and accelerations felt by an insect are predicted to be anisotropic even when the small-scale turbulence (measured at a fixed point or along the trajectory of a fluid-particle) is isotropic. Our results thus provide further evidence that insects do indeed use turbulent velocity and acceleration cues as indicators of the mean wind direction
Can aliphatic anchoring groups be utilised with dyes for p-type dye sensitized solar cells?
A series of novel laterally anchoring tetrahydroquinoline derivatives have been synthesized and investigated for their use in NiO-based p-type dye-sensitized solar cells. The kinetics of charge injection and recombination at the NiO-dye interface for these dyes have been thoroughly investigated using picosecond transient absorption and time-resolved infrared measurements. It was revealed that despite the anchoring unit being electronically decoupled from the dye structure, charge injection occurred on a sub picosecond timescale. However, rapid recombination was also observed due to the close proximity of the electron acceptor on the dyes to the NiO surface, ultimately limiting the performance of the p-DSCs
The Sloan Digital Sky Survey Reverberation Mapping Project: Rapid CIV Broad Absorption Line Variability
We report the discovery of rapid variations of a high-velocity CIV broad
absorption line trough in the quasar SDSS J141007.74+541203.3. This object was
intensively observed in 2014 as a part of the Sloan Digital Sky Survey
Reverberation Mapping Project, during which 32 epochs of spectroscopy were
obtained with the Baryon Oscillation Spectroscopic Survey spectrograph. We
observe significant (>4sigma) variability in the equivalent width of the broad
(~4000 km/s wide) CIV trough on rest-frame timescales as short as 1.20 days
(~29 hours), the shortest broad absorption line variability timescale yet
reported. The equivalent width varied by ~10% on these short timescales, and by
about a factor of two over the duration of the campaign. We evaluate several
potential causes of the variability, concluding that the most likely cause is a
rapid response to changes in the incident ionizing continuum. If the outflow is
at a radius where the recombination rate is higher than the ionization rate,
the timescale of variability places a lower limit on the density of the
absorbing gas of n_e > 3.9 x 10^5 cm^-3. The broad absorption line variability
characteristics of this quasar are consistent with those observed in previous
studies of quasars, indicating that such short-term variability may in fact be
common and thus can be used to learn about outflow characteristics and
contributions to quasar/host-galaxy feedback scenarios.Comment: 15 pages, 14 figures. Accepted for publication in the Astrophysical
Journa
Dietary changes in migrant adolescents with increasing length of stay in Australia and associated risk of wheeze – a retrospective, cross sectional study
A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder
We report observations of 240 Cepheid variables obtained with the Near
Infrared Camera (NICMOS) through the F160W filter on the Hubble Space Telescope
(HST). The Cepheids are distributed across six recent hosts of Type Ia
supernovae (SNe Ia) and the "maser galaxy" NGC 4258, allowing us to directly
calibrate the peak luminosities of the SNe Ia from the precise, geometric
distance measurements provided by the masers. New features of our measurement
include the use of the same instrument for all Cepheid measurements across the
distance ladder and homogeneity of the Cepheid periods and metallicities thus
necessitating only a differential measurement of Cepheid fluxes and reducing
the largest systematic uncertainties in the determination of the fiducial SN Ia
luminosity. The NICMOS measurements reduce differential extinction in the host
galaxies by a factor of 5 over past optical data. Combined with an expanded of
240 SNe Ia at z<0.1 which define their magnitude-redshift relation, we find
H_0=74.2 +/-3.6, a 4.8% uncertainty including both statistical and systematic
errors. We show that the factor of 2.2 improvement in the precision of H_0 is a
significant aid to the determination of the equation-of-state of dark energy, w
= P/(rho c^2). Combined with the WMAP 5-year measurement of Omega_M h^2, we
find w= -1.12 +/- 0.12 independent of high-redshift SNe Ia or baryon acoustic
oscillations (BAO). This result is also consistent with analyses based on the
combination of high-z SNe Ia and BAO. The constraints on w(z) now with high-z
SNe Ia and BAO are consistent with a cosmological constant and improved by a
factor of 3 from the refinement in H_0 alone. We show future improvements in
H_0 are likely and will further contribute to multi-technique studies of dark
energy.Comment: 60 pages, 15 figures Accepted for Publication, ApJ. This is the
second of two papers reporting results from a program to determine the Hubble
constant to 5% precision from a refurbished distance ladder based on
extensive use of differential measurement
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