21,259 research outputs found
Obesity and the Rate of Time Preference: Is there a Connection?
We hypothesize that recent trends in U.S. and worldwide obesity are, in part, related to an increase in the marginal rate of time preference, where time preference refers to the rate at which people are willing to trade current benefit for future benefit. The higher the rate of time preference, the larger is the factor by which individuals discount the future health risks associated with current consumption. Data from the United States, as well as international evidence, suggests that a relationship between these two variables is plausible. We encourage researchers to explore the possible link between obesity and time preference, as important insights are likely to result.time preference; obesity
European Springtails Orchesella cincta (L.) and O. villosa (L.) (Collembola: Entomobryidae): Vagabond Species of the Nearctic Region
North American specimens of the European invasive springtail Orchesella cincta (L.) were compared to several published European haplotypes in a phylogenetic framework using likelihood methods based on a portion of cytochrome oxidase II (cox2). Our analyses provide direct evidence of at least two distinct introductions of this invasive to North America from different regions of Europe. Additional introduction events cannot be ruled out because detection is limited by extremely low sequence divergence among populations inhabiting different regions of the continent. Orchesella villosa (L.), another invasive from Europe, is another candidate for multiple introductions. Herein we include the cox2 sequence from single specimens of O. villosa from Maine and Oregon. Although these two specimens are identical in sequence, they differ from a published sequence from a European specimen by 15%, indicating significant undocumented genetic variation in the natal range of O. villosa. Additional sampling of Nearctic populations of O. villosa might reveal the same situation reported herein for O. cincta
Red Runaways: Hypervelocity Stars, Hills Ejecta and Other Outliers in the F-M Star Regime
In this paper we analyze a sample of metal-rich (>-0.8 dex) main sequence
stars in the extended solar neighborhood, investigating kinematic outliers from
the background population. The data, which are taken from the Sloan Digital Sky
Survey, are kinematically profiled as a function of distance from the Galactic
plane using full six dimensional phase space information. Each star is examined
in the context of these kinematic profiles and likelihoods are assigned to
quantify whether a star matches the underlying profile. Since some of these
stars are likely to have been ejected from the disc, we trace back their orbits
in order to determine potential ejection radii. We find that objects with low
probability (i.e. `outliers') are typically more metal poor, faster and, most
importantly, have a tendency to originate from the inner Galaxy compared to the
underlying population.
We also compose a sample of stars with velocities exceeding the local escape
velocity. Although we do not discount that our sample could be contaminated by
objects with spurious proper motions, a number of stars appear to have been
ejected from the disc with exceptionally high velocities. Some of these are
consistent with being ejected from the spiral arms and hence are a rich
resource for further study. Finally we look at objects whose orbits are
consistent with them being ejected at high speeds from the Galactic center. Of
these objects we find that one, J135855.65+552538.19, is inconsistent with
halo, bulge and disk kinematics and could plausibly have been ejected from the
Galactic nucleus via a Hills mechanism.Comment: 17 Pages, 12 Figures, Accepted to A
Exercise, Obesity and CNS Control of Metabolic Homeostasis: A Review
This review details the manner in which the central nervous system regulates metabolic homeostasis in normal weight and obese rodents and humans. It includes a review of the homeostatic contributions of neurons located in the hypothalamus, the midbrain and limbic structures, the pons and the medullary area postrema, nucleus tractus solitarius, and vagus nucleus, and details how these brain regions respond to circulating levels of orexigenic hormones, such as ghrelin, and anorexigenic hormones, such as glucagon-like peptide 1 and leptin. It provides an insight as to how high intensity exercise may improve homeostatic control in overweight and obese subjects. Finally, it provides suggestions as to how further progress can be made in controlling the current pandemic of obesity and diabetes
Ionization Equilibrium Timescales in Collisional Plasmas
Astrophysical shocks or bursts from a photoionizing source can disturb the
typical collisional plasma found in galactic interstellar media or the
intergalactic medium. The spectrum emitted by this plasma contains diagnostics
that have been used to determine the time since the disturbing event, although
this determination becomes uncertain as the elements in the plasma return to
ionization equilibrium. A general solution for the equilibrium timescale for
each element arises from the elegant eigenvector method of solution to the
problem of a non-equilibrium plasma described by Masai (1984) and Hughes &
Helfand (1985). In general the ionization evolution of an element Z in a
constant electron temperature plasma is given by a coupled set of Z+1 first
order differential equations. However, they can be recast as Z uncoupled first
order differential equations using an eigenvector basis for the system. The
solution is then Z separate exponential functions, with the time constants
given by the eigenvalues of the rate matrix. The smallest of these eigenvalues
gives the scale of slowest return to equilibrium independent of the initial
conditions, while conversely the largest eigenvalue is the scale of the fastest
change in the ion population. These results hold for an ionizing plasma, a
recombining plasma, or even a plasma with random initial conditions, and will
allow users of these diagnostics to determine directly if their best-fit result
significantly limits the timescale since a disturbance or is so close to
equilibrium as to include an arbitrarily-long time.Comment: 4 pages, 2 figures. Accepted for publication by the Astrophysical
Journa
An X-Ray Study of the Supernova Remnant G290.1-0.8
G290.1-0.8 (MSH 11-61A) is a supernova remnant (SNR) whose X-ray morphology
is centrally bright. However, unlike the class of X-ray composite SNRs whose
centers are dominated by nonthermal emission, presumably driven by a central
pulsar, we show that the X-ray emission from G290.1-0.8 is thermal in nature,
placing the remnant in an emerging class which includes such remnants as W44,
W28, 3C391, and others. The evolutionary sequence which leads to such X-ray
properties is not well understood. Here we investigate two scenarios for such
emission: evolution in a cloudy interstellar medium, and early-stage evolution
of a remnant into the radiative phase, including the effects of thermal
conduction. We construct models for these scenarios in an attempt to reproduce
the observed center-filled X-ray properties of G290.1-0.8, and we derive the
associated age, energy, and ambient density conditions implied by the models.
We find that for reasonable values of the explosion energy, the remnant age is
of order (1 - 2) x 10^{4} yr. This places a fairly strong constraint on any
association between G290.1-0.8 and PSR J1105-610, which would require an
anomalously large velocity for the pulsar.Comment: 7 pages, 7 figures, ApJ, accepte
Concerns with AED conversion: comparison of patient and physician perspectives.
When discussing AED conversion in the clinic, both the patient and physician perspectives on the goals and risks of this change are important to consider. To identify patient-reported and clinician-perceived concerns, a panel of epilepsy specialists was questioned about the topics discussed with patients and the clinician's perspective of patient concerns. Findings of a literature review of articles that report patient-expressed concerns regarding their epilepsy and treatment were also reviewed. Results showed that the specialist panel appropriately identified patient-reported concerns of driving ability, medication cost, seizure control, and medication side effects. Additionally, patient-reported concerns of independence, employment issues, social stigma, medication dependence, and undesirable cognitive effects are important to address when considering and initiating AED conversion
Adaptive homodyne measurement of optical phase
We present an experimental demonstration of the power of real-time feedback
in quantum metrology, confirming a theoretical prediction by Wiseman regarding
the superior performance of an adaptive homodyne technique for single-shot
measurement of optical phase. For phase measurements performed on weak coherent
states with no prior knowledge of the signal phase, we show that the variance
of adaptive homodyne estimation approaches closer to the fundamental quantum
uncertainty limit than any previously demonstrated technique. Our results
underscore the importance of real-time feedback for reaching quantum
performance limits in coherent telecommunication, precision measurement and
information processing.Comment: RevTex4, color PDF figures (separate files), submitted to PR
Effects of Post-Exercise Hypotension After A Graded Exercise Test
The purpose of the study was to explore post-exercise hyoptension (PEH) responses after a graded exercise test. PEH has been recommended by physicians to help physiologically control hypertension in patients. Recent studies have tried to find the relationships between PEH and hypertensive individuals but the results have been inconclusive, although certain studies have found that individuals with pre-hypertension tend to decrease their blood pressure the most. This study was a approved by the TAMU-SA IRB and all subjects provided written consent. Subjects were asked to not eat a heavy meal or consume caffeine three hours prior to testing. After sitting for five minutes, subject\u27s blood pressure was measured by the investigator using a sphygmomanometer, after which they performed a treadmill test to exhaustion (VO2max) using the Bruce protocol. Immediately post exercise (IPE) subjects sat down and BP was measured. Subjects remained seated and were measured at 5, 10, and 15 minutes post-exercise. Based upon the VO2max results, the sample was divided into higher (\u3e 40.8 ml/kg/min, Age= 24.8 +/- 3.5 yrs, Ht= 170.0 +/- 8.6 cm, Wt 72.20+/- 13.3 kg, BMI = 24.8 +/- 3.0) and lower fit (\u3c 40.8 ml/kg/min, Age = 28.2 +/- 9.1 yrs, Ht= 164.9 +/- 7.4 cm, Wt= 82.8 +/- 20.8 kg, BMI= 30.4+/- 7.1) groups and a 2 (category) X 5 (time) factorial ANOVA was used to explore differences between groups and time-points. Alpha was set t .05 for all tests. While there were no significant differences in systolic and diastolic BP readings at any time-points between higher and lower fit groups (P\u3e.05), there was only a significant main effect of time on diastolic BP at the 5, 10, and 15 min points
DEVELOPMENT OF A TL-3 F-SHAPE TEMPORARY CONCRETE MEDIAN BARRIER
A temporary concrete median barrier (CMB) was designed and tested for compliance under the Test Level 3 (TL-3) guidelines specified in the Recommended Procedures for the Safety Performance Evaluation of Highway Features, National Cooperative Highway Research Program (NCHRP) Report No. 350. The barrier is built to the new metric standards and has a traditional pin and loop configuration for interconnection. The objective of this research project was to develop and evaluate a standardized, temporary concrete barrier design while addressing the concerns for safety, economy, structural integrity, constructability, ease of installation, and maintenance. The resulting F-shape barrier segment is 3,800-mm long, a length that reduced the number of connections while limiting the weight of the barriers to ease handling. Full-scale crash testing demonstrated several critical design features. First, the connections need to be tight initially as practicable to limit deformation and rotation of the barriers,. Secondly, the pin needs to restrain the longitudinal barrier forces. Full-scale compliance testing of the final design demonstrated that the barrier was capable of successfully redirecting the 2000-kg vehicle. The vehicle demonstrated significant roll after contact with the barrier, which is evidenced in a majority of other concrete barrier tests. This barrier provides economical work zone protection applicable in a variety of situations, where TL-3 test criteria is warranted
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