Magnetic shielding and vacuum test for passive hydrogen masers

Vibration tests on high permeability magnetic shields used in the SAO-NRL Advanced Development Model (ADM) hydrogen maser were made. Magnetic shielding factors were measured before and after vibration. Preliminary results indicate considerable (25%) degradation. Test results on the NRL designed vacuum pumping station for the ADM hydrogen maser are also discussed. This system employs sintered zirconium carbon getter pumps to pump hydrogen plus small ion pumps to pump the inert gases. In situ activation tests and pumping characteristics indicate that the system can meet design specifications

The Rapidly Fading Afterglow from the Gamma-Ray Burst of 1999 May 6

We report on the discovery of the radio afterglow from the gamma-ray burst (GRB) of 1999 May 6 (GRB 990506) using the Very Large Array (VLA). The radio afterglow was detected at early times (1.5 days), but began to fade rapidly sometime between 1 and 5 days after the burst. If we attribute the radio emission to the forward shock from an expanding fireball, then this rapid onset of the decay in the radio predicts that the corresponding optical transient began to decay between 1 and 5 minutes after the burst. This could explain why no optical transient for GRB 990506 was detected in spite of numerous searches. The cause of the unusually rapid onset of the decay for the afterglow is probably the result of an isotropically energetic fireball expanding into a low density circumburst environment. At the location of the radio afterglow we find a faint (R ~ 24 mag) host galaxy with a double morphology.Comment: in press at ApJ Letters, 13 page LaTeX document includes 2 postscript figure

PSR J1909-3744, a Binary Millisecond Pulsar with a Very Small Duty Cycle

We report the discovery of PSR J1909-3744, a 2.95 millisecond pulsar in a nearly circular 1.53 day orbit. Its narrow pulse width of 43 microseconds allows pulse arrival times to be determined with great accuracy. We have spectroscopically identified the companion as a moderately hot (T = 8500 K) white dwarf with strong absorption lines. Radial velocity measurements of the companion will yield the mass ratio of the system. Our timing data suggest the presence of Shapiro delay; we expect that further timing observations, combined with the mass ratio, will allow the first accurate determination of a millisecond pulsar mass. We have measured the timing parallax and proper motion for this pulsar which indicate a transverse velocity of 140 (+80/-40) km/s. This pulsar's stunningly narrow pulse profile makes it an excellent candidate for precision timing experiments that attempt to detect low frequency gravitational waves from coalescing supermassive black hole binaries.Comment: 12 pages, 4 figures. Accepted for publication in ApJ

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

Bringing Transportation into a Cap-and-Trade Regime

Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).The U.S. may at some point adopt a national cap-and-trade system for greenhouse gases, and if and when that happens the system of CAFE regulation of vehicle design very likely could still be in place. Imposed independently these two systems can lead to economic waste. One way to avoid the inefficiency is to integrate the two systems by allowing emissions trading between them. Two possible approaches to potential linkage are explored here, along with a discussion of ways to guard against violation under such a trading regime of vehicle standards that may be justified by non-climate objectives. At a minimum, implementation of a U.S. cap-and-trade system is several years in the future, so we also suggest intermediate measures that would gain some of the advantages of an integrated system and smooth the way to ultimate interconnection.This study received funding from the MIT Joint Program on the Science and Policy of Global Change, which is supported by a consortium of government, industry and foundation sponsors

Developing a health state classification system from NEWQOL for epilepsy using classical psychometric techniques and Rasch analysis: a technical report

Aims: Resource allocation amongst competing health care interventions is informed by evidence of both clinical- and cost-effectiveness. Cost-utility analysis is increasingly used to assess cost effectiveness through the use of Quality Adjusted Life Years (QALYs). This requires health state values. Generic measures of health related quality of life (HRQL) are usually used to produce these values, but there are concerns about their relevance and sensitivity in epilepsy. This study develops a health state classification system for epilepsy from the NEWQOL battery, a validated questionnaire measuring QoL in epilepsy. The classification system will be amenable to valuation for calculating QALYs. Methods: Factor and other psychometric analyses were undertaken to investigate the factor structure of the battery, and assess the validity and responsiveness of the items. These analyses were used alongside Rasch analysis to select the dimensions included in the classification system, and the items used to represent each domain. Analysis was carried out on a trial dataset of patients with epilepsy (n=1611). Rasch and factor analysis were performed on one half of the sample and validated on the remaining half. Dimensions and items were selected that performed well across all analyses. Results: The battery was found to demonstrate reliability and validity but responsiveness across time periods for many of the items was low. A six dimension classification system was developed: worry about seizures, depression, memory, cognition, stigmatism and control, each with four response levels. Conclusions: It is feasible to develop a health state classification system from a battery of instruments using a combination of classical psychometric, factor and Rasch analysis. This is the first condition-specific health state classification developed for epilepsy and the next stage will produce preference weights to enable the measure to be used in cost-utility analysis.quality adjusted life years; health related quality of life; Rasch analysis; preference-based measures of health; health states; epilepsy

Measurement of Orbital Decay in the Double Neutron Star Binary PSR B2127+11C

We report the direct measurement of orbital period decay in the double neutron star pulsar system PSR B2127+11C in the globular cluster M15 at the rate of $(-3.95 \pm 0.13) \times 10^{-12}$, consistent with the prediction of general relativity at the $\sim 3$ level. We find the pulsar mass to be $m_p = (1.358 \pm 0.010) M_\odot$ and the companion mass $m_c = (1.354 \pm 0.010) M_\odot$. We also report long-term pulse timing results for the pulsars PSR B2127+11A and PSR B2127+11B, including confirmation of the cluster proper motion.Comment: 12 pages, 4 figures, accepted for publication in ApJ

Early infant feeding and adiposity risk: from infancy to adulthood

Introduction: Systematic reviews suggest that a longer duration of breast-feeding is associated with a reduction in the risk of later overweight and obesity. Most studies examining breast-feeding in relation to adiposity have not used longitudinal analysis. In our study, we aimed to examine early infant feeding and adiposity risk in a longitudinal cohort from birth to young adulthood using new as well as published data. Methods: Data from the Western Australian Pregnancy Cohort (Raine) Study in Perth, W.A., Australia, were used to examine associations between breast-feeding and measures of adiposity at 1, 2, 3, 6, 8, 10, 14, 17, and 20 years. Results: Breast-feeding was measured in a number of ways. Longer breast-feeding (in months) was associated with reductions in weight z-scores between birth and 1 year (β = -0.027; p \u3c 0.001) in the adjusted analysis. At 3 years, breast-feeding for \u3c4 months increased the odds of infants experiencing early rapid growth (OR 2.05; 95% CI 1.43-2.94; p \u3c 0.001). From 1 to 8 years, children breast-fed for ≤4 months compared to ≥12 months had a significantly greater probability of exceeding the 95th percentile of weight. The age at which breast-feeding was stopped and a milk other than breast milk was introduced (introduction of formula milk) played a significant role in the trajectory of the BMI from birth to 14 years; the 4-month cutoff point was consistently associated with a higher BMI trajectory. Introduction of a milk other than breast milk before 6 months compared to at 6 months or later was a risk factor for being overweight or obese at 20 years of age (OR 1.47; 95% CI 1.12-1.93; p = 0.005). Discussion: Breast-feeding until 6 months of age and beyond should be encouraged and is recommended for protection against increased adiposity in childhood, adolescence, and young adulthood. Adverse long-term effects of early growth acceleration are fundamental in later overweight and obesity. Formula feeding stimulates a higher postnatal growth velocity, whereas breast-feeding promotes slower growth and a reduced likelihood of overweight and obesity. Biological mechanisms underlying the protective effect of breast-feeding against obesity are based on the unique composition and metabolic and physiological responses to human milk