5,955 research outputs found
Some Comments on an MeV Cold Dark Matter Scenario
We discuss several aspects of astroparticle physics pertaining to a new model
with MeV cold dark matter particles, which annihilate to electron-positron
pairs in a manner yielding the correct CDM density required today, and
explaining the enhanced electron-positron annihilation line from the center of
the Galaxy. We note that the mass of the vector meson mediating the
annihilations, should exceed the mass of CDM particle, and comment on possible
enhancement due to CDM clustering, on the detectability of the new CDM, and on
particle physics models incorporating this scenario.Comment: 13 pages, 2 figures. v2 - Added some remarks regarding a more
stringent mass bound. References added, some typos corrected. v3 - Added a
comment regarding the invalidity of perturbative calculation in the case of a
very small coupling g'. Removed the comment regarding the smallness of the
angular width of the 511 keV lin
Predicting Revision Following In Situ Ulnar Nerve Decompression for Patients With Idiopathic Cubital Tunnel Syndrome.
PURPOSE: To determine the incidence of revision and potential risk factors for needing revision surgery following in situ ulnar nerve decompression for patients with idiopathic cubital tunnel syndrome (CTS).
METHODS: We conducted a retrospective chart review of all patients treated at 1 specialty hand center with an open in situ ulnar nerve decompression for idiopathic CTS from January 2006 through December 2010. Revision incidence was determined by identifying patients who underwent additional surgeries for recurrent or persistent ulnar nerve symptoms. Bivariate analysis was performed to determine which variables had a significant influence on the need for revision surgery.
RESULTS: Revision surgery was required in 3.2% (7 of 216) of all cases. Age younger than 50 years at the time of index decompression was the lone significant predictor of need for revision surgery. Other patient factors, including gender, diabetes, smoking history, and workers\u27 compensation status were not predictive of the need for revision surgery. Disease-specific variables including nerve conduction velocities, McGowan grading, and predominant symptom type were also not predictive of revision.
CONCLUSIONS: For patients with idiopathic CTS, the risk of revision surgery following in situ ulnar nerve decompression is low. However, this risk was increased in patients who were younger than 50 years at the time of the index procedure. The findings of this study suggest that, in the absence of underlying elbow arthritis or prior elbow trauma, in situ ulnar nerve decompression is an effective, minimal-risk option for the initial surgical treatment of CTS.
TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic III
Evaluation and Management of Sleep Disorders in the Hand Surgery Patient.
Despite posing a significant public health threat, sleep disorders remain poorly understood and often underdiagnosed and mismanaged. Although sleep disorders are seemingly unrelated, hand surgeons should be mindful of these because numerous conditions of the upper extremity have known associations with sleep disturbances that can adversely affect patient function and satisfaction. In addition, patients with sleep disorders are at significantly higher risk for severe, even life-threatening medical comorbidities, further amplifying the role of hand surgeons in the recognition of this condition
Determination of the glycoforms of human chorionic gonadotropin b-core fragment by matrix-assisted laser desoption/ionisation time of flight mass spectrometry
Background: Metabolism of human chorionic gonadotropin (hCG) in the serum and kidney yields the terminal urinary product hCG ß-core fragment (hCGßcf), comprising two disulfide-linked peptides (ß6-ß40 and ß55-ß92) of which one (ß6-ß40) retains truncated N-linked sugars. Hyperglycosylated hCGßcf may indicate choriocarcinoma or Down syndrome, but the glycosylation profile of hCGßcf has not been thoroughly evaluated.
Methods: hCGßcf, purified from pregnancy urine, was reduced by "on-target" dithiothreitol (DTT) reduction and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The mass ([M+H]+) of the primary sequence of the glycosylated peptide ß6-ß40 was subtracted from the m/z values of the discrete peaks observed to give the masses of the carbohydrate moieties. Carbohydrate structure was predicted by sequentially subtracting the masses of the monosaccharide residues corresponding to N-linked carbohydrates of the hCG ß-subunit reported in the literature.
Results: Mass spectra of hCGßcf revealed a broad triple peak at m/z 8700–11300. After reduction, the triple peak was replaced by a discrete set of peaks between m/z 4156 and 6354. A peak at m/z 4156.8 corresponded to the nonglycosylated peptide (ß55-ß92). The remaining nine peaks indicated that urinary hCGßcf comprises a set of glycoforms smaller and larger than the trimannosyl core.
Conclusions: hCGßcf comprises a wider set of glycoforms than reported previously. Peaks of highest mass indicate evidence of hyperglycosylated carbohydrate moieties. The data support previous reports that hCGßcf oligosaccharides lack sialic acid and galactose residues. No indication was found of a ß6-ß40 peptide that was entirely devoid of carbohydrate
Xenon excimer emission from multicapillary discharges in direct current mode
Microdischarges in xenon have been generated in a pressure range of 400–1013 mbar with a fixed flow rate of 100 sccm. These microdischarges are obtained from three metallic capillary tubes in series for excimer emission. Total discharge voltage is thrice as large as that of a single capillary discharge tube at current levels of up to 12 mA. Total spectral irradiance of vacuum ultraviolet (VUV) emission also increases significantly compared to that of the single capillary discharge. Further, the irradiance of the VUV emission is strongly dependent on pressure as well as the discharge current
The Influence on Climate Change of Differing Scenarios for Future Development Analyzed Using the MIT Integrated Global System Model
Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).A wide variety of scenarios for future development have played significant roles in climate policy discussions. This paper presents projections of greenhouse gas (GHG) concentrations, sea level rise due to thermal expansion and glacial melt, oceanic acidity, and global mean temperature increases computed with the MIT Integrated Global Systems Model (IGSM) using scenarios for 21st century emissions developed by three different groups: intergovernmental (represented by the Intergovernmental Panel on Climate Change), government (represented by the U.S. government Climate Change Science Program) and industry (represented by Royal Dutch Shell plc). In all these scenarios the climate system undergoes substantial changes. By 2100, the CO2 concentration ranges from 470 to 1020 ppm compared to a 2000 level of 365 ppm, the CO2-equivalent concentration of all greenhouse gases ranges from 550 to 1780 ppm in comparison to a 2000 level of 415 ppm, sea level rises by 24 to 56 cm relative to 2000 due to thermal expansion and glacial melt, oceanic acidity changes from a current pH of around 8 to a range from 7.63 to 7.91. The global mean temperature increases by 1.8 to 7.0 degrees C relative to 2000.The IGSM model used here is supported by the U.S. Department of Energy, U.S. Environmental Protection Agency, U.S. National Science Foundation, U.S. National Aeronautics and Space Administration, U.S. National Oceanographic and Atmospheric Administration and the Industry and Foundation Sponsors of the MIT Joint Program on the Science and Policy of Global Change
Geographic and Age-Based Variations in Medicare Reimbursement Among ASSH Members.
Background: The purpose of this study was to investigate how American Society for Surgery of the Hand (ASSH) members\u27 Medicare reimbursement depends on their geographical location and number of years in practice. Methods: Demographic data for surgeons who were active members of the ASSH in 2012 were obtained using information publicly available through the US Centers for Medicare and Medicaid Services (CMS). Hand-surgeons-per-capita and average reimbursement per surgeon were calculated for each state. Regression analysis was performed to determine a relationship between (1) each state\u27s average reimbursement versus the number of ASSH members in that state, (2) average reimbursement versus number of hand surgeons per capita, and (3) total reimbursement from Medicare versus number of years in practice. Analysis of variance (ANOVA) was used to detect a difference in reimbursement based on categorical range of years as an ASSH member. Results: A total of 1667 ASSH members satisfied inclusion in this study. Although there was significant variation among states\u27 average reimbursement, reimbursement was not significantly correlated with the state\u27s hand surgeons per capita or total number of hand surgeons in that given state. Correlation between years as an ASSH member and average reimbursement was significant but non-linear; the highest reimbursements were seen in surgeons who had been ASSH members from 8 to 20 years. Conclusions: Peak reimbursement from Medicare for ASSH members appears to be related to the time of surgeons\u27 peak operative volume, rather than any age-based bias for or against treating Medicare beneficiaries. In addition, though geographic variation in reimbursement does exist, this does not appear to correlate with density or availability of hand surgeons
Having Fun While Enhancing Student Engagement: Creative Approaches in Online Learning
This article explores various creative approaches to integrate into online counselor education classrooms. Creative approaches to learning help encourage students to be involved in classroom discussions or activities; while enhancing their critical thinking skills, professional development, and inclusivity within the classroom. This article explores the intention behind integrating creative approaches into online learning and offers several resources that instructors can use in their online classrooms
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Studying the effect of oral transmission on melodic structure using online iterated singing experiments
ince generations, singing and speech have been mainly transmitted orally. How does oral transmission shape the evolution of music? Here, we developed a method for conducting online transmission experiments, in which sung melodies are passed from one singer to the next. We show that cognitive and motor constraints play a profound role in the emergence of melodic structure. Specifically, initially random tones develop into more structured systems that increasingly reuse and combine fewer elements, making melodies easier to learn and transmit over time. We discuss how our findings are compatible with melodic universals found in most human cultures and culturally specific characteristics of participants' previous musical exposure. Overall, our method efficiently automates online singing experiments while enabling large-scale data collection using standard computers available to everyone. We see great potential in further extending this work to increase the efficiency, scalability, and diversity of research on cultural evolution and cognitive science
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