1,186 research outputs found
Conversation Piece: National Service, is it for Us?
Many of the writers, conceptual developers, and advocates of a National Service Program for the United States credit William James with issuing, in 1910, the first call to youth to be enlisted in a program entitled The Moral Equivalent of War,\u27\u27 The program was envisioned to engage youth in industrial work and social service, according to their skills and interests. While that did not come to fruition, we saw some forms of it instituted during the bleak days and years of the Great Depression in the 1930\u27s. Thousands of youth were enlisted in the Civilian Conservation Corps beginning in 1933, and even more thousands of youth were employed under the National Youth Administration. These programs came to an end as we entered World War II, and the nation sent its young men and some young women to war. Meanwhile, all of America entered a war economy
Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for GLAST
A study of the statistics of cosmological black-hole jet sources is applied
to EGRET blazar data, and predictions are made for GLAST. Black-hole jet
sources are modeled as collimated relativistic plasma outflows with radiation
beamed along the jet axis due to strong Doppler boosting. The comoving rate
density of blazar flares is assumed to follow a blazar formation rate (BFR),
modeled by analytic functions based on astronomical observations and fits to
EGRET data. The redshift and size distributions of gamma-ray blazars observed
with EGRET, separated into BL Lac object (BL) and flat spectrum radio quasar
(FSRQ) distributions, are fit with monoparametric functions for the
distributions of the jet Lorentz factor \Gamma, comoving directional power
l'_e, and spectral slope. A BFR factor ~10 x greater at z ~ 1 than at present
is found to fit the FSRQ data. A smaller comoving rate density and greater
luminosity of BL flares at early times compared to the present epoch fits the
BL data. Based on the EGRET observations, ~1000 blazars consisting of ~800
FSRQs and FR2 radio galaxies and ~200 BL Lacs and FR1 radio galaxies will be
detected with GLAST during the first year of the mission. Additional AGN
classes, such as hard-spectrum BL Lacs that were mostly missed with EGRET,
could add more GLAST sources. The FSRQ and BL contributions to the EGRET
gamma-ray background at 1 GeV are estimated at the level of ~10 - 15% and ~2 -
4%, respectively. EGRET and GLAST sensitivities to blazar flares are considered
in the optimal case, and a GLAST analysis method for blazar detection is
outlined.Comment: 17 pages, 9 figures, ApJ, in press, v.660, May 1, 2007 (minor changes
from previous version
Drugs In the Workplace: A Manager\u27s Guide
Drugs in the workplace is a growing problem that threatens a valuable human resource - the employee. Managers in the hospitality industry can take a proactive stance in meeting the problem head on. The authors discuss what managers can do
Identifying Venous Thromboembolism in Cancer Patients Using Veterans Affairs Administrative Data
Identifying Venous Thromboembolism in Cancer Patients Using Veterans Affairs Administrative Data
Noah Ravenborg1, Najeebah A. Bade, M.D.2, Dalia Abdelaziz Mobarek, M.D.1, 2, 3
1 George Washington University School of Medicine and Health Sciences, Washington, D.C. 2 Department of Medicine, Section of Hematology, Veterans Affairs Medical Center, Washington, D.C., 3 Department of Medicine, Section of Hematology & Medical Oncology, George Washington University Medical Center, Washington, D.C. Noah Ravenborg Cell phone: (310)-804-0848, Email: [email protected], MS2
IMPORTANCE: The validity of administrative data in identifying diagnoses within the Veterans Affairs (VA) database, including viral hepatitis, cirrhosis, H. pylori, and cancer metastasis has been reported. International Classification of Diseases-9 (ICD-9) validity for venous thromboembolism (VTE) in cancer patients within the VA database is unknown.
OBJECTIVES: Determine the validity of ICD-9 codes for VTE in cancer patients in a local VA database.
DESIGN: We conducted a retrospective study utilizing data from the Washington, DC VA Cancer Registry and the Electronic Health Records (EHR). VTE diagnosis was identified using the ICD-9 codes for Pulmonary Embolism and Thrombosis, with subsequent confirmation via comprehensive chart reviews.
SETTING: Veterans Affairs Medical Center, Washington, DC.
PARTICIPANTS: 6,678 patients with cancer were identified from 1999-2015 using the cancer registry. We applied the algorithms above and identified subjects with VTE in the database.
EXPOSURES: N/A
MAIN OUTCOME(S) AND MEASURE(S): The primary outcome study measurement was the validity of ICD-9 for VTE in cancer patients. Positive (PPV), negative predictive (NPV) values, sensitivity, specificity, and likelihood ratios were calculated. Our hypothesis, that ICD-9 codes alone are not predicative of VTE diagnosis in our cancer registry, was formulated during data collection after initial chart reviews yielded false positives.
RESULTS: Initial application of ICD-9 codes for VTE among 6,678 subjects yielded 616 VTE. Chart reviews confirmed the presence of VTE among 403/616. The ICD-9 codes had a 65% PPV, 95% NPV, 57% sensitivity and 96.4% specificity. Estimated prevalence of VTE in 6,678 subjects is 10.6%. Positive and negative likelihood ratios were 15.8 and 0.45, respectively.
CONCLUSIONS AND RELEVANCE: Within our local VA database, ICD-9 codes for VTE are not sensitive for identifying patients with VTE. Accurate ICD coding by physicians is paramount for patient care and research purposes. There is a lack of data on physician coding education. A systematic literature review revealed variable ICD-9 code validity based on the population of interest making larger studies challenging with added need for manual abstraction for validation. Provider education on proper use of ICD code is important for health outcomes research perspective and would allow for more accurate retrospective research.
REGISTRATION: N/
The Giant X-Ray Flare of NGC 5905: Tidal Disruption of a Star, a Brown Dwarf, or a Planet?
We model the 1990 giant X-ray flare of the quiescent galaxy NGC 5905 as the
tidal disruption of a star by a supermassive black hole. From the observed
rapid decline of the luminosity, over a timescale of a few years, we argue that
the flare was powered by the fallback of debris rather than subsequent
accretion via a thin disk. The fallback model allows constraints to be set on
the black hole mass and the mass of debris. The latter must be very much less
than a solar mass to explain the very low luminosity of the flare. The
observations can be explained either as the partial stripping of the outer
layers of a low-mass main sequence star or as the disruption of a brown dwarf
or a giant planet. We find that the X-ray emission in the flare must have
originated within a small patch rather than over the entire torus of
circularized material surrounding the black hole. We suggest that the patch
corresponds to the ``bright spot'' where the stream of returning debris impacts
the torus. Interestingly, although the peak luminosity of the flare was highly
sub-Eddington, the peak flux from the bright spot was close to the Eddington
limit. We speculate on the implications of this result for observations of
other flare events.Comment: 25 pages, including 5 figure
X-ray Observations of Gravitationally Lensed Quasars; Evidence for a Hidden Quasar Population
The large magnification factors of gravitationally lensed (GL) systems allow
us to investigate the properties of quasars with X-ray luminosities that are
substantially lower than those of unlensed ones and also provide an independent
means of estimating the contribution of faint quasars to the hard X-ray
component of the cosmic X-ray background. Our spectral analysis indicate a
flattening of the spectral index in the hard band (4-20keV restframe) for 2
radio-loud quasars in the GL quasar sample for which the data have moderate
signal-to-noise ratio. We have identified a large fraction of Broad Absorption
Line (BAL) quasars amongst the GL quasar population. We find that approximately
35% of radio-quiet GL quasars contain BAL features which is significantly
larger than the 10% fraction of BAL quasars presently found in optically
selected flux limited quasar samples. We present a simple model that estimates
the effects of attenuation and lens magnification on the luminosity function of
quasars and that explains the observed fraction of GL BAL quasars. These
observations suggest that a large fraction of BAL quasars are missed from flux
limited optical surveys. Modeling of several X-ray observations of the GL BAL
quasar PG1115+080 suggests that the observed large X-ray variability may be
caused in part by a variable intrinsic absorber consistent with previously
observed variability of the BAL troughs in the UV band. The observed large
X-ray flux variations in PG1115+080 offer the prospect of considerably reducing
errors in determining the time delay with future X-ray monitoring of this
system and hence constraining the Hubble constant H.Comment: 19 pages, 10 figures, 9 Tables, accepted for publication in Ap
Physiology and Pathology of Drug Hypersensitivity: Role of Human Leukocyte Antigens
Drug Hypersensitivity reactions can be distinguished in adverse drug events and adverse drug reactions. They represent a major problem in the medical scheme, since they are often underestimated. Pharmacogenetic analysis demonstrated significant associations between emerging hypersensitivity reactions and distinct genes of the HLA complex. HLA-mediated hypersensitivity reactions particularly affect skin and liver, however, impairment of the bone marrow and kidney function could also be observed. These life threatening medical conditions can be attributed to the activation of autologous drug-specific T-cells. Severe drug hypersensitivity reactions that resemble acute GvHD are linked to certain specific HLA alleles. The most common hypersensitivity reactions occur after the treatment of HLA-B*57:01+ HIV patients with abacavir and HLA-A*31:01+ or B*15:02+ epileptic patients with carbamazepine (CBZ)
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