4,714 research outputs found
Age- and sex- specific all-cause mortality risk greatest in metabolic syndrome combinations with elevated blood pressure from 7 U.S. cohorts
Background
The association between metabolic syndrome (MetS) and all-cause mortality is well established but it is unclear if there are differences in mortality risk among the 32 possible MetS combinations. Hence, the purpose of this study is to evaluate the associations between different MetS combinations and its individual components with all-cause mortality, and to examine differences in the association by age and sex.
Methods
A merged sample of 82,717 adults from 7 U.S. cohorts was used.
Results
In our sample, MetS was present in 32% of men, 34% of women, 28% of younger adults (18ā65 years) and 62% of older adults (>65 years) with 14,989 deaths over 14.6 Ā± 7.4 years of follow-up. Risk of all-cause mortality was higher in younger individuals with a greater number of MetS factors present, but in older adults having all 5 MetS factors was the only combination significantly associated with mortality. Regardless of age or sex, elevated blood pressure was the MetS factor most consistently present in MetS combinations that were significantly and most strongly associated with mortality. In fact, elevated blood pressure in the absence of other risk factors was significantly associated with mortality in men (HR, 95% CI = 1.56, 1.33ā1.84), women (HR = 1.62, 1.44ā1.81) and younger adults (HR = 1.61, 1.45ā1.79). Conversely, waist circumference, glucose and triglycerides in isolation were not associated with mortality (p>0.05).
Conclusion
In a large U.S. population, different combinations of MetS components vary substantially in their associations with all-cause mortality. Men, women and younger individuals with MetS combinations including elevated blood pressure had stronger associations with greater mortality risk, with minimal associations between MetS and mortality risk in older adults. Thus, we suggest that future algorithms may wish to consider differential weighting of these common metabolic risk factors, particularly in younger populations.York University Librarie
Post-Oligarchic Evolution of Protoplanetary Embryos and the Stability of Planetary Systems
We investigate the orbit-crossing time (T_c) of protoplanet systems both with
and without a gas-disk background. The protoplanets are initially with equal
masses and separation (EMS systems) scaled by their mutual Hill's radii. In a
gas-free environment, we find log (T_c/yr) = A+B \log (k_0/2.3). Through a
simple analytical approach, we demonstrate that the evolution of the velocity
dispersion in an EMS system follows a random walk. The stochastic nature of
random-walk diffusion leads to (i) an increasing average eccentricity ~
t^1/2, where t is the time; (ii) Rayleigh-distributed eccentricities
(P(e,t)=e/\sigma^2 \exp(-e^2/(2\sigma^2)) of the protoplanets; (iii) a
power-law dependence of T_c on planetary separation. As evidence for the
chaotic diffusion, the observed eccentricities of known extra solar planets can
be approximated by a Rayleigh distribution. We evaluate the isolation masses of
the embryos, which determine the probability of gas giant formation, as a
function of the dust and gas surface densities.Comment: 15 pages, 13 figures (2 color ones), accepted for publication in Ap
An inexpensive open-source ultrasonic sensing system for monitoring liquid levels
Ā Liquid levels are measured in a variety of agricultural applications, and are often measured manually, which can be time-consuming and labor-intensive.Ā Rapid advances in electronic technologies have made a variety of inexpensive sensing, monitoring, and control capabilities available.Ā A monitoring system was developed and evaluated for automatic measurement of liquid levels, and demonstrated by monitoring water levels in evaporation pans used in evaporation studies and irrigation scheduling.Ā The system is composed of an ultrasonic sensor, a microcontroller-based data logger, and a temperature sensor.Ā The ultrasonic sensor measures the distance from the sensor to the liquid surface.Ā Air temperature is measured by the temperature sensor, and is used to compensate for changes in the speed of sound due to air-temperature variations to improve accuracy of ultrasonic distance measurements.Ā The datalogger is programmed to take measurements and to store data on a memory card which can be downloaded for processing and analysis.Ā All components of the system were assembled in a PVC housing.Ā The system was tested in the field, and resulted in water levels measured by the system corresponding very closely to those measured manually (R2 > 0.98). Ā This system is inexpensive, with total cost of US$85, and easy to build, install, and maintain. Ā In addition to monitoring liquid levels, the system could be adapted to a variety of other measurements. Ā Keywords: Ultrasonic sensor, liquid level, microcontroller, open-source hardware, datalogger, USA
Evolution of Solar Magnetic Field and Associated Multi-wavelength Phenomena: Flare events on 20 November 2003
We analyze H-alpha images, soft X-ray profiles, magnetograms, extreme
ultra-violet images and radio observations of two homologous flare events
(M1.4/1N and M9.6/2B) on 20 November 2003 in the active region NOAA 10501 and
study properties of reconnection between twisted filament systems, energy
release and associated launch of coronal mass ejections (CMEs). During both
events twisted filaments observed in H-alpha approached each other and
initiated the flare processes. However, the second event showed the formation
of cusp as the filaments interacted. The rotation of sunspots of opposite
polarities, inferred from magnetograms likely powered the twisted filaments and
injection of helicity. Along the current sheet between these two opposite
polarity sunspots, the shear was maximum, which could have caused the twist in
the filament. At the time of interaction between filaments, the reconnection
took place and flare emission in thermal and non-thermal energy ranges attained
the maximum. The radio signatures revealed the opening of field lines resulting
from reconnection. The H-alpha images and radio data provide the inflow speed
leading to reconnection and the scale size of particle acceleration region. The
first event produced a narrow and slow CME, whereas the later one was
associated with a fast full halo CME. The halo CME signatures observed between
Sun and Earth using white-light and scintillation images and in-situ
measurements indicated the magnetic energy utilized in the expansion and
propagation. The magnetic cloud signature at the Earth confirmed the flux rope
ejected at the time of filament interaction and reconnection.Comment: 22 pages, 16 figures, Accepted for the publication in Astrophysical
Journal (APJ
Impacts of Large-Scale Circulation on Convection: A 2-D Cloud Resolving Model Study
Studies of impacts of large-scale circulation on convection, and the roles of convection in heat and water balances over tropical region are fundamentally important for understanding global climate changes. Heat and water budgets over warm pool (SST=29.5 C) and cold pool (SST=26 C) were analyzed based on simulations of the two-dimensional cloud resolving model. Here the sensitivity of heat and water budgets to different sizes of warm and cold pools is examined
Reconnection Outflows and Current Sheet Observed with Hinode/XRT in the 2008 April 9 "Cartwheel CME" Flare
Supra-arcade downflows (SADs) have been observed with Yohkoh/SXT (soft X-rays
(SXR)), TRACE (extreme ultra-violet (EUV)), SoHO/LASCO (white light),
SoHO/SUMER (EUV spectra), and Hinode/XRT (SXR). Characteristics such as low
emissivity and trajectories which slow as they reach the top of the arcade are
consistent with post-reconnection magnetic flux tubes retracting from a
reconnection site high in the corona until they reach a lower-energy magnetic
configuration. Viewed from a perpendicular angle, SADs should appear as
shrinking loops rather than downflowing voids. We present XRT observations of
supra-arcade downflowing loops (SADLs) following a coronal mass ejection (CME)
on 2008 April 9 and show that their speeds and decelerations are consistent
with those determined for SADs. We also present evidence for a possible current
sheet observed during this flare that extends between the flare arcade and the
CME. Additionally, we show a correlation between reconnection outflows observed
with XRT and outgoing flows observed with LASCO.Comment: 32 pages, 23 figures, Accepted for publication by the Astrophysical
Journal (Oct. 2010
Graphene-based hybrid plasmonic waveguide for highly efficient broadband mid-infrared propagation and modulation
Ā© 2018 Optical Society of America. In this paper, a graphene-based hybrid plasmonic waveguide is proposed for highly efficient broadband surface plasmon polariton (SPP) propagation and modulation at mid-infrared (mid-IR) spectrum. The hybrid plasmonic waveguide is composed of a monolayer graphene sheet in the center, a polysilicon gating layer, and two inner dielectric buffer layers and two outer parabolic-ridged silicon substrates symmetrically placed on both sides of the graphene. Owing to the unique parabolic-ridged waveguide structure, the light-graphene interaction and subwavelength SPPs confinement of the fundamental SPP mode for the hybrid waveguide can be significantly increased. Under the graphene chemical potential of 1.0 eV, the proposed waveguide can achieve outstanding SPP propagation performance with long propagation length of 12.1-16.7 Ī¼m and small normalized mode area of ~10ā4 in the frequency range of 10-20 THz, exhibiting more than one order smaller in the normalized mode area while remaining the propagation length almost the same level with respect to the hybrid plasmonic waveguide without parabolic ridges. By tuning the graphene chemical potential from 0.1 to 1.0 eV, we demonstrate the waveguide has a modulation depth greater than 51% for the frequency ranging from 10 to 20 THz and reaches a maximum of nearly 100% at the frequency higher than 18 THz. Benefitting from the excellent broadband mid-IR propagation and modulation performance, the graphene-based hybrid plasmonic waveguide may open up a new way for various mid-IR waveguides, modulators, interconnects and optoelectronic devices
Chandra Observation of the Cluster of Galaxies MS 0839.9+2938 at z=0.194: the Central Excess Iron and SN Ia Enrichment
We present the Chandra study of the intermediately distant cluster of
galaxies MS 0839.9+2938. By performing both the projected and deprojected
spectral analyses, we find that the gas temperature is approximately constant
at about 4 keV in 130-444h_70^-1 kpc. In the inner regions, the gas temperature
descends towards the center, reaching <~ 3 keV in the central 37h_70^-1 kpc.
This infers that the lower and upper limits of the mass deposit rate are 9-34
M_sun yr^-1 and 96-126 M_sun yr^-1, respectively within 74h_70^-1 kpc where the
gas is significantly colder. Along with the temperature drop, we detect a
significant inward iron abundance increase from about 0.4 solar in the outer
regions to about 1 solar within the central 37h_70^-1 kpc. Thus MS 0839.9+2938
is the cluster showing the most significant central iron excess at z>~ 0.2. We
argue that most of the excess iron should have been contributed by SNe Ia. By
utilizing the observed SN Ia rate and stellar mass loss rate, we estimate that
the time needed to enrich the central region with excess iron is 6.4-7.9 Gyr,
which is similar to those found for the nearby clusters. Coinciding with the
optical extension of the cD galaxy (up to about 30h_70^-1 kpc), the observed
X-ray surface brightness profile exhibits an excess beyond the distribution
expected by either the beta model or the NFW model, and can be well fitted with
an empirical two-beta model that leads to a relatively flatter mass profile in
the innermost region.Comment: Accepted for publication in Ap
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