1,016 research outputs found
Macroeconomic effects of the Barcelona Initiative
This paper compares ex post and ex ante assessments of the macroeconomic effects of trade liberalization in the Mediterranean. Using implications from a standard Ramsey growth model augmented for anticipation and implementation effects, we pool cross section and time series data to estimate ex post the effects of trade liberalization on a set of Arabic Southern Mediterranean Partner countries (SMPCs). We find significant and robust evidence for positive effects on major macro variables and discuss the appropriate policies. Second, we review a number of computable general equilibrium (CGE) studies which aimed at assessing the macroeconomic impacts for the same countries ex ante. CGE projections are very much at odds with the econometric findings and the biases seem to be systematic for all macro variables. Third, we use ANOVA techniques to identify possible shortcomings both with respect to design and target country of the CGE study. We find that even well-designed CGE studies targeted to an average type of country do not seem to yield reliable results. Overall, our analysis suggests that there is no sound statistical evidence to believe that CGE analysis has been useful in assessing the macroeconomic effects of trade liberalization in the Mediterranean. But we find considerable econometric evidence to support the view that free trade policies have enhanced growth in the MENA region
Chandra Detection of the X-ray counterpart of the High-magnetic field Radio Pulsar J1119-6127 in the Supernova Remnant G292.2-0.5
We report the Chandra Advanced CCD Imaging Spectrometer detection of the
X-ray counterpart of the high magnetic field, ~1600 year-old, 407 ms radio
pulsar J1119-6127 associated with the supernova remnant G292.2-0.5. The
powerful imaging capability of Chandra also unveiled, for the first time, a
faint 3"x6" pulsar wind nebula (PWN) at energies above ~1.2 keV. The X-ray
emission from the pulsar and its associated nebula is well described by an
absorbed power law model with a photon index of 2.2 (1.9-2.8). The
corresponding 0.5-10 keV unabsorbed X-ray luminosity is 5.5(2.2-15.5)x10^32
ergs/s (at 6 kpc). When compared to two other pulsars with similar spin and
magnetic properties, J1119-6127 stands out as being the least efficient at
turning rotational kinetic energy into X-ray emission. This study shows that
high magnetic field radio pulsars can be significant X-ray emitters and Chandra
is needed to study the emission properties of the pulsars and associated faint
PWNe.Comment: 6 pages, 5 figures. To appear in ApJL July 10 2003 (submitted April
10 2003, accepted May 22 2003
Examining the Correlation between Acute Behavioral Manifestations of Concussion and the Underlying Pathophysiology of Chronic Traumatic Encephalopathy: A Pilot Study
Concussion in athletes can contribute to early neuropsychological changes that may be indicative of future neurodegenerative disease. One of the hallmark findings of chronic traumatic encephalopathy is anxiety and impulsive behavior that often develops early in the course of the disease. The behavioral dysfunction can be grouped into a broader category referred to as cognitive disruption. The current gold standard for diagnosing chronic neurodegeneration is post-mortem evaluation of tauopathy to identify neurofibrillary tau tangles in neurons. Few studies, however, have looked at clinical correlations between acute injury and chronic neurodegeneration in terms of behavior. This lack of focus towards translational study has limited advancements towards treatment. In this pilot investigation, the acute cognitive and emotional (anger, impulsivity, and anxiety) affects of concussion in a cohort of collegiate athletes (n = 30) are examined and compared to findings in the post-mortem pathologic features of chronic traumatic encephalopathy. Specifically, the role of the seroternergic system with alpha synuclein and tauopathy staining and the potential for early clinically relevant behavioral and pharmaceutical interventions was investigated. The purpose was to determine if athletes began demonstrating cognitive disruption present in post-mortem evaluation during the acute phase of injury. The acute data was collected via questionnaires within ten days of the athletesâ concussion diagnosis. Results demonstrated that 11 of 30 athletes (36%) scored in a diagnosable range of anxiety post-concussion, and athletes scored above the norm in state-anger (M = 22.9, SD = 9.99), indicating severe emotional disturbance. A limitation is that due to the long time frame from acute injury to the development of neurodegeneration individual athletes cannot be tracked in longevity thus limiting the findings to the realm of correlation. The findings from this pilot study warrant further investigation into the neuropsychological aspects for how to manage concussion and prevent degenerative disease
New Constraints on the Energetics, Progenitor Mass, and Age of the Supernova Remnant G292.0+1.8 Containing PSR J1124-5916
We present spatially resolved spectroscopy of the supernova remnant (SNR)
G292.0+1.8 with the Chandra X-ray observatory. This SNR contains the 135 ms
pulsar, J1124-5916. We apply non-equilibrium ionization (NEI) models to the
data. By comparing the derived abundances with those predicted from
nucleosynthesis models, we estimate a progenitor mass of 30-40 solar masses. We
also derive the intrinsic parameters of the supernova explosion such as its
energy, the age of the SNR, the blast wave velocity, and the swept-up mass. In
the Sedov interpretation, our estimated SNR age of 2,600 years is close to the
pulsar's characteristic age of 2,900 years. This confirms the pulsar/SNR
association and relaxes the need for the pulsar to have a non-canonical value
for the braking index, a large period at birth or a large transverse velocity.
We discuss the properties of the pulsar wind nebula (PWN) in the light of the
Kennel and Coroniti model and estimate the pulsar wind magnetization parameter.
We also report the first evidence for steepening of the power law spectral
index with increasing radius from the pulsar.Comment: 5 pages, 3 figures. To appear in ApJL, Feb 1 2003 (submitted Oct 9
2002, accepted Dec 19 2002
Parallax and Kinematics of PSR B0919+06 from VLBA Astrometry and Interstellar Scintillometry
Results are presented from a long-term astrometry program on PSR B0919+06
using the NRAO Very Long Baseline Array. With ten observations (seven epochs)
between 1994--2000, we measure a proper motion of 18.35 +/- 0.06 mas/yr in RA,
86.56 +/- 0.12 mas/yr in Dec, and a parallax of 0.83 +/- 0.13 mas (68%
confidence intervals). This yields a pulsar distance of 1.21 +/- 0.19 kpc,
making PSR B0919+06 the farthest pulsar for which a trigonometric parallax has
been obtained, and the implied pulsar transverse speed is 505 +/- 80 km/s.
Combining the distance estimate with interstellar scintillation data spanning
20 years, we infer the existence of a patchy or clumpy scattering screen along
the line of sight in addition to the distributed electron density predicted by
models for the Galaxy, and constrain the location of this scattering region to
within about 250 parsecs of the Sun. Comparison with the lines of sight towards
other pulsars in the same quadrant of the Galaxy permits refinement of our
knowledge of the local interstellar matter in this direction.Comment: 12 pages, includes 4 figures and 3 tables, uses AASTeX 5 (included);
ApJ submitte
X-ray Observation and Analysis of The Composite Supernova Remnant G327.1-1.1
Based on the data from the observation of the SNR G327.1-1.1 by ASCA and
ROSAT, we find that G327.1-1.1 is a composite remnant with both a nonthermal
emission component and a diffuse thermal emission component. The nonthermal
component is well fitted by a power-law model with photon index about 2.2. This
component is attributed to the emission from the synchrotron nebula powered by
an undiscovered central pulsar. The thermal component has a temperature of
about 0.4 keV. We attribute it to the emission from the shock-heat swept-up
ISM. Its age, explosion energy and density of ambient medium are derived from
the observed thermal component. Some charactistics about the synchrotron nebula
are also derived. We search for the pulsed signal, but has not found it. The
soft X-ray(0.4 - 2 keV) and hard X-ray(2 - 10 keV) images are different, but
they both elongate in the SE-NW direction. And this X-ray SE-NW elongation is
in positional coincidence with the radio ridge in MOST 843MHz radio map. We
present a possibility that the X-ray nonthermal emission mainly come from the
trail produced by a quickly moving undiscoverd pulsar, and the long radio ridge
is formed when the pulsar is moving out of the boundary of the plerionic
structure.Comment: 20 pages, 4 Postscript figures, aasms4.sty and psfig.sty, to be
published in Astrophysical Journal, January 20, 1999, Vol. 51
Mortality risk for different presenting complaints amongst older patients assessed with the Manchester triage system
Purpose: Older people often present to the Emergency Department with nonspecific complaints. We aimed (1) to examine characteristics of older patients presenting to the ED triaged with the presentational flowchart âunwell adultâ of the Manchester triage system (MTS) and (2) to assess the different mortality and admission rates among triage categories. Methods: Retrospective cohort study including all consecutive patients aged 70Â years and older who visited the ED of a tertiary care hospital in the Netherlands during a 1-year period. The primary outcome was 30-day mortality. Secondary outcomes were 7-day mortality, hospital admission and ED length of stay. Results: 4255 patients were included in this study. Mean age was 78Â years (IQR 73.9â83.4) and 2098 were male (49.3%). The MTS presentational flowchart âunwell adultâ was the most commonly used flowchart (n = 815, 19.3%). After the infrequent flowchart âmajor traumaâ (n = 9, 13.8%), âunwell adultâ had the highest 30-day mortality (n = 88, 10.8%). When compared to all other flowcharts, patients assigned as âunwell adultâ have significantly higher 30-day mortality rates (OR 1.89 (95%CI 1.46â2.46), p = < 0.001), also when adjusted for age, gender and triage priority (OR 1.75 (95%CI 1.32â2.31), p = < 0.001). Patients from the âunwell adultâ flowchart had the highest hospital admission rate (n = 540, 66.3%), and had among the longest ED length of stay. Conclusions: Older ED patients are most commonly assigned the presentational flowchart âunwell adultâ when using the MTS. Patients in this category have the highest non-trauma mortality and highest hospital admission rates when compared to other presenting complaints
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