5,064 research outputs found

    Predicting Trade Expansion under FTAs and Multilateral Agreements

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    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

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    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

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    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

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    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 (3\sim 3 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

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    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

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    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.

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    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

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    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

    Funding Needed for Assessments of Weed Biological Control

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