On the Correlation of Torque and Luminosity in GX 1+4

Over five years of daily hard X-ray (>20 keV) monitoring of the 2-min accretion-powered pulsar GX 1+4 with the Compton Gamma Ray Observatory/BATSE large-area detectors has found nearly continuous rapid spin-down, interrupted by a bright 200-d spin-up episode. During spin-down, the torque becomes more negative as the luminosity increases (assuming that the 20-60 keV pulsed flux traces bolometric luminosity), the opposite of what is predicted by standard accretion torque theory. No changes in the shape of the 20-100 keV pulsed energy spectrum were detected, so that a very drastic change in the spectrum below 20 keV or the pulsed fraction would be required to make the 20-60 keV pulsed flux a poor luminosity tracer. These are the first observations which flatly contradict standard magnetic disk accretion theory, and they may have important implications for understanding the spin evolution of X-ray binaries, cataclysmic variables, and protostars. We briefly discuss the possibility that GX 1+4 may be accreting from a retrograde disk during spin-down, as previously suggested.Comment: 10 pages including 3 PS figures. To appear in ApJ Letter

Low-grade pelvic masses with spindle cell and fibroblastic proliferation: a case report

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Comparing health workforce forecasting approaches for healthcare planning: The case for ophthalmologists

Health workforce planning is essential in the provision of quality healthcare. Several approaches to planning are customarily used and advocated, each with unique underlying assumptions. Thus, a thorough understanding of each assumption is required in order to make an informed decision on the choice of forecasting approach to be used. For illustration, we compare results for eye care requirements in Singapore using three established workforce forecasting approaches – workforce-to-population-ratio, needs based approach, utilization based approach – and a proposed robust integrated approach to discuss the appropriateness of each approach under various scenarios. Four simulation models using the systems modeling methodology of system dynamics were developed for use in each approach. These models were initialized and simulated using the example of eye care workforce planning in Singapore, to project the number of ophthalmologists required up to the year 2040 under the four different approaches. We found that each approach projects a different number of ophthalmologists required over time. The needs based approach tends to project the largest number of required ophthalmologists, followed by integrated, utilization based and workforce-to-population ratio approaches in descending order. The four different approaches vary widely in their forecasted workforce requirements and reinforce the need to be discerning of the fundamental differences of each approach in order to choose the most appropriate one. Further, health workforce planning should also be approached in a comprehensive and integrated manner that accounts for developments in demographic and healthcare systems

Torque Reversal and Spin-Down of the Accretion-Powered Pulsar 4U 1626-67

Over 5 yr of hard X-ray (20-60 keV) monitoring of the 7.66 s accretion-powered pulsar 4U 1626-67 with the Compton Gamma Ray Observatory/BATSE large-area detectors has revealed that the neutron star is now steadily spinning down, in marked contrast to the steady spin-up observed during 1977-1989. This is the second accreting pulsar (the other is GX 1+4) that has shown extended, steady intervals of both spin-up and spin-down. Remarkably, the magnitudes of the spin-up and spin-down torques differ by only 15%, with the neutron star spin changing on a timescale |ν/dot ν| ≈ 5000 yr in both states. The current spin-down rate is itself decreasing on a timescale |dot ν/bar ν| ≈ 26 yr. The long-term timing history shows small-amplitude variations on a 4000 day timescale, which are probably due to variations in the mass transfer rate. The pulsed 20-60 keV emission from 4U 1626-67 is well-fitted by a power-law spectrum with photon index γ = 4.9 and a typical pulsed intensity of 1.5 × 10^(-10) ergs cm^(-2) s^(-1). The low count rates with BATSE prohibited us from constraining the reported 42 minute binary orbit, but we can rule out long-period orbits in the range 2 days lesssim Porb lesssim 900 days. We compare the long-term torque behavior of 4U 1626-67 to other disk-fed accreting pulsars and discuss the implications of our results for the various theories of magnetic accretion torques. The abrupt change in the sign of the torque is difficult to reconcile with the extremely smooth spin-down now observed. The strength of the torque noise in 4U 1626-67, ~10^(-22) Hz^2 s^(-2) Hz^(-1), is the smallest ever measured for an accreting X-ray pulsar, and it is comparable to the timing noise seen in young radio pulsars. We close by pointing out that the core temperature and external torque (the two parameters potentially relevant to internal sources of timing noise) of an accreting neutron star are also comparable to those of young radio pulsars

Special Care Dentistry Curriculum at The Undergraduate Level : Students’ Prespective

Special needs patients (SNP) have difficulty accessing dental services, partly due to reluctance of dentists to treat them. Objective: We assess didactic and clinical training experiences of final-year dental students and new graduates in managing SNP. Methods: An online questionnaire was sent to 123 final year dental students and new graduates, assessing their experiences and readiness in handling SNP. Results: Majority of the respondents were not confident in attending to SNP. Majority gained knowledge in handling SNP via lectures while more than half had managed patients with complex medical history. Majority mentioned a lack of clinical training to treat SNP as their dental training experience had only been in a dental school clinical setting. Most of the respondents hope their curriculum would include more education to improve clinical skills in managing SNP. Conclusion: Respondents demonstrated minimum training and lack of confidence and skills that might contribute to a lack of preparedness to manage the oral health care needs of SNP. Clinical exposure in managing SNP at the undergraduate level is still inadequate and it needs to be emphasized in the curriculum.DOI: 10.14693/jdi.v22i3.976

The fate of steroid estrogens: Partitioning during wastewater treatment and onto river sediments

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 Springer Science+Business Media B.V.The partitioning of steroid estrogens in wastewater treatment and receiving waters is likely to influence their discharge to, and persistence in, the environment. This study investigated the partitioning behaviour of steroid estrogens in both laboratory and field studies. Partitioning onto activated sludge from laboratory-scale Husmann units was rapid with equilibrium achieved after 1 h. Sorption isotherms and Kd values decreased in the order 17α-ethinyl estradiol > 17α-estradiol > estrone > estriol without a sorption limit being achieved (1/n >1). Samples from a wastewater treatment works indicated no accumulation of steroid estrogens in solids from primary or secondary biological treatment, however, a range of steroid estrogens were identified in sediment samples from the River Thames. This would indicate that partitioning in the environment may play a role in the long-term fate of estrogens, with an indication that they will be recalcitrant in anaerobic conditions.EPSR

Future requirements for and supply of ophthalmologists for an aging population in Singapore

#### Background Singapore’s population, as that of many other countries, is aging; this is likely to lead to an increase in eye diseases and the demand for eye care. Since ophthalmologist training is long and expensive, early planning is essential. This paper forecasts workforce and training requirements for Singapore up to the year 2040 under several plausible future scenarios. #### Methods The Singapore Eye Care Workforce Model was created as a continuous time compartment model with explicit workforce stocks using system dynamics. The model has three modules: prevalence of eye disease, demand, and workforce requirements. The model is used to simulate the prevalence of eye diseases, patient visits, and workforce requirements for the public sector under different scenarios in order to determine training requirements. #### Results Four scenarios were constructed. Under the baseline business-as-usual scenario, the required number of ophthalmologists is projected to increase by 117% from 2015 to 2040. Under the current policy scenario (assuming an increase of service uptake due to increased awareness, availability, and accessibility of eye care services), the increase will be 175%, while under the new model of care scenario (considering the additional effect of providing some services by non-ophthalmologists) the increase will only be 150%. The moderated workload scenario (assuming in addition a reduction of the clinical workload) projects an increase in the required number of ophthalmologists of 192% by 2040. Considering the uncertainties in the projected demand for eye care services, under the business-as-usual scenario, a residency intake of 8–22 residents per year is required, 17–21 under the current policy scenario, 14–18 under the new model of care scenario, and, under the moderated workload scenario, an intake of 18–23 residents per year is required. #### Conclusions The results show that under all scenarios considered, Singapore’s aging and growing population will result in an almost doubling of the number of Singaporeans with eye conditions, a significant increase in public sector eye care demand and, consequently, a greater requirement for ophthalmologists

Coherent Quantum Oscillations in a Silicon Charge Qubit

Fast quantum oscillations of a charge qubit in a double quantum dot fabricated in a Si/SiGe heterostructure are demonstrated and characterized experimentally. The measured inhomogeneous dephasing time T2* ranges from 127ps to ~2.1ns; it depends substantially on how the energy difference of the two qubit states varies with external voltages, consistent with a decoherence process that is dominated by detuning noise(charge noise that changes the asymmetry of the qubit's double-well potential). In the regime with the shortest T2*, applying a charge-echo pulse sequence increases the measured inhomogeneous decoherence time from 127ps to 760ps, demonstrating that low-frequency noise processes are an important dephasing mechanism.Comment: 5 pages plus 3 page supplemental (8 pages total

nicord single unit expanded umbilical cord blood transplantation ucbt final results of a multicenter phase i ii trial

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