5,064 research outputs found
Predicting Trade Expansion under FTAs and Multilateral Agreements
This paper examines the historical record of eight recent free trade agreements (FTAs). It also investigates the predictive power of two popular quantitative world trade models—the single-equation gravity model and the multiequation comput-able general equilibrium (CGE) model—as applied to three major trade liberalization agreements adopted during the 1990s: Mercosur, NAFTA, and the Uruguay Round Agreement, using the Rose gravity model and the GTAP general equilibrium model. Both models are found accurate in some instances, but intervening influences in the wake of trade liberalization episodes confound the challenge of drawing a strong conclusion in favor of one modeling approach over the other. Between the “naïve” gravity model and “naïve” CGE model predictions, we find that the former tends to overpredict intrabloc trade expansion (especially over horizons of five years and less) while the latter tends to underpredict. CGE models remain favored for ex post analysis of welfare impacts and the direct and indirect linkages between policy reforms and the numerous other economic variables of concern to policymakers and the public at large.gravity models, CGE models, regional trading arrangements
The HR 4796A Debris System: Discovery of Extensive Exo-Ring Dust Material
The optically and IR bright, and starlight-scattering, HR 4796A ring-like
debris disk is one of the most (and best) studied exoplanetary debris systems.
The presence of a yet-undetected planet has been inferred (or suggested) from
the narrow width and inner/outer truncation radii of its r = 1.05" (77 au)
debris ring. We present new, highly sensitive, Hubble Space Telescope (HST)
visible-light images of the HR 4796A circumstellar debris system and its
environment over a very wide range of stellocentric angles from 0.32" (23 au)
to ~ 15" (1100 au). These very high contrast images were obtained with the
Space Telescope Imaging Spectrograph (STIS) using 6-roll PSF-template
subtracted coronagraphy suppressing the primary light of HR 4796A and using
three image plane occulters and simultaneously subtracting the background light
from its close angular proximity M2.5V companion. The resulting images
unambiguously reveal the debris ring embedded within a much larger,
morphologically complex, and bi-axially asymmetric exoring scattering
structure. These images at visible wavelengths are sensitive to, and map, the
spatial distribution, brightness, and radial surface density of micron size
particles over 5 dex in surface brightness. These particles in the exo-ring
environment may be unbound from the system and interacting with the local ISM.
Herein we present a new morphological and photometric view of the larger than
prior seen HR 4796A exoplanetary debris system with sensitivity to small
particles at stellocentric distances an order of magnitude greater than has
previously been observed.Comment: 28 pages, 17 figures, accepted for publication in the Astronomical
Journal 21 December 201
Trends in the Globular Cluster Luminosity Function of Early-Type Galaxies
We present results from a study of the globular cluster luminosity function
(GCLF) in a sample of 89 early-type galaxies observed as part of the ACS Virgo
Cluster Survey. Using a Gaussian parametrization of the GCLF, we find a highly
significant correlation between the GCLF dispersion, sigma, and the galaxy
luminosity, M_B, in the sense that the GC systems in fainter galaxies have
narrower luminosity functions. The GCLF dispersions in the Milky Way and M31
are fully consistent with this trend, implying that the correlation between
sigma and galaxy luminosity is more fundamental than older suggestions that
GCLF shape is a function of galaxy Hubble type. We show that the sigma - M_B
relation results from a bonafide narrowing of the distribution of (logarithmic)
cluster masses in fainter galaxies. We further show that this behavior is
mirrored by a steepening of the GC mass function for relatively high masses, M
>~ 3 x 10^5 M_sun, a mass regime in which the shape of the GCLF is not strongly
affected by dynamical evolution over a Hubble time. We argue that this trend
arises from variations in initial conditions and requires explanation by
theories of cluster formation. Finally, we confirm that in bright galaxies, the
GCLF "turns over" at the canonical mass scale of M_TO ~ 2 x 10^5 M_sun.
However, we find that M_TO scatters to lower values (~1-2 x 10^5 M_sun) in
galaxies fainter than M_B >~ -18.5, an important consideration if the GCLF is
to be used as a distance indicator for dwarf ellipticals.Comment: 4 pages, 3 figures. Accepted for publication in ApJ Letters. Also
available at http://www.cadc.hia.nrc.gc.ca/community/ACSVCS/publications.htm
The Age Difference between the Globular Cluster Sub-populations in NGC 4472
The age difference between the two main globular cluster sub-populations in
the Virgo giant elliptical galaxy, NGC 4472 (M 49), has been determined using
HST WFPC2 images in the F555W and F814W filters. Accurate photometry has been
obtained for several hundred globular clusters in each of the two main
sub-populations, down to more than one magnitude below the turn-over of their
luminosity functions. This allows precise determinations of both the mean
colors and the turn-over magnitudes of the two main sub-populations. By
comparing the data with various population synthesis models, the
age-metallicity pairs that fit both the observed colors and magnitudes have
been identified. The metal-poor and the metal-rich globular clusters are found
to be coeval within the errors ( Gyr). If one accepts the validity of
our assumptions, these errors are dominated by model uncertainties. A
systematic error of up to 4 Gyr could affect this result if the blue and the
red clusters have significantly different mass distributions. However, that one
sub-population is half as old as the other is excluded at the 99% confidence
level. The different globular cluster populations are assumed to trace the
galaxy's major star-formation episodes. Consequently, the vast majority of
globular clusters, and by implication the majority of stars, in NGC 4472 formed
at high redshifts but by two distinct mechanisms or in two episodes.Comment: 32 pages, including 12 postscript figures, accepted for publication
in the Astronomical Journal, December 1999 issu
Upper Body Muscular Activation during Variations of Push-Ups in Healthy Men
International Journal of Exercise Science 6(4) : 278-288, 2013. The purpose of this study was to assess neural activity for upper body musculature in college-age men during repetitions of a conventional pushup or a Perfect PushupTM. Eighteen healthy men (21.6±1 yr, 182.5±7 cm, 87.4±15 kg) completed five repetitions of a conventional pushup and Perfect PushupTM while using a wide hand base of support for the upper body. Body position, hand placement, and cadence of the pushup were standardized. Root mean square electromyography (RMS-EMG, mV/Sec) was collected for the triceps brachii (TB), pectoralis major (PM), serratus anterior (SA), and posterior deltoid (PD) during all repetitions. RMS-EMG values were normalized to a maximal voluntary isometric contraction in the pushup position (%MVICPU). For each muscle, %MVICPU for repetitions 1, 3, and 5 were analyzed for differences due to type of push-up. No differences in %MVICPU due to type ofpush-up for the TB (p=0.079) or the SA (p=0.45) were detected. The Perfect PushupTM increased %MVICPU compared to the conventional pushup (44%, p\u3c0.05). Additionally, the Perfect PushupTM increased %MVICPU by the third repetition (p\u3c0.05) while the conventional pushup did not until the 5th repetition. The conventional pushup activated more PD (76%, p\u3c0.05). The type of push-up that requires the greatest neural activity for a given number of repetitions should result in improved adaptations. The Perfect PushupTM was superior for activating the pectoralis major while individuals would elicit more neural activation in the posterior deltoid by conventional push-ups. Trainers and rehabilitation specialists should consider these data when attempting to train or isolate upper body skeletal muscles using a push-up movement
Accelerator performance analysis of the Fermilab Muon Campus
Fermilab is dedicated to hosting world-class experiments in search of new
physics that will operate in the coming years. The Muon g-2 Experiment is one
such experiment that will determine with unprecedented precision the muon
anomalous magnetic moment, which offers an important test of the Standard
Model. We describe in this study the accelerator facility that will deliver a
muon beam to this experiment. We first present the lattice design that allows
for efficient capture, transport, and delivery of polarized muon beams. We then
numerically examine its performance by simulating pion production in the
target, muon collection by the downstream beam line optics, as well as
transport of muon polarization. We finally establish the conditions required
for the safe removal of unwanted secondary particles that minimizes
contamination of the final beam.Comment: 10 p
The Impact of Depression on Patient Outcomes in Hip Arthroscopic Surgery.
Background: Mental health impairments have been shown to negatively affect preoperative self-reported function in patients with various musculoskeletal disorders, including those with femoroacetabular impingement.
Hypothesis: Those with symptoms of depression will have lower self-reported function, more pain, and less satisfaction on initial assessment and at 2-year follow-up than those without symptoms of depression.
Study Design: Cohort study; Level of evidence, 3.
Methods: Patients who were enrolled in a multicenter hip arthroscopic surgery registry and had 2-year outcome data available were included in the study. Patients completed the 12-item International Hip Outcome Tool (iHOT-12), visual analog scale (VAS) for pain, and 12-item Short-Form Health Survey (SF-12) when consenting for surgery. At 2-year follow-up, patients were emailed the iHOT, the VAS, and a rating scale of surgical satisfaction. Initial SF-12 mental component summary (MCS) scores
Results: A total of 781 patients achieved the approximate 2-year milestone (mean follow-up, 735 ± 68 days), with 651 (83%) having 2-year outcome data available. There were 434 (67%) female and 217 (33%) male patients, with a mean age of 35.8 ± 13.0 years and a mean body mass index of 25.4 ± 8.8 kg/m
Conclusion: A large number of patients who underwent hip arthroscopic surgery presented with symptoms of depression, which negatively affected self-reported function, pain levels, and satisfaction on initial assessment and at 2-year follow-up. Surgeons who perform hip arthroscopic surgery may need to identify the symptoms of depression and be aware of the impact that depression can have on surgical outcomes
First Record of the Southern Red-Backed Vole, Clethrionomys gapperi, in Newfoundland: Implications for the Endangered Newfoundland Marten, Martes americana atrata
We report on the first capture of the Southern Red-backed Vole (Clethrionomys gapperi), the eleventh non-native terrestrial mammal established on the island of Newfoundland over the last 150 years. Red-backed Voles may have been accidentally introduced by unknown sources in pulpwood imports or may have been deliberately introduced in an attempt to augment the depauperate small mammal fauna as a vigilante recovery effort for the endangered Newfoundland Marten (Martes americana atrata). We anticipate significant utilization of the Red-backed Vole as prey by both Newfoundland Marten and Red Fox (Vulpes vulpes) with associated demographic responses within and between these species. Red-backed Voles will likely change habitat utilization patterns for the endemic subspecies of Meadow Vole, Microtus pennsylvanicus terraenovae
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