On defining the Hamiltonian beyond quantum theory

Energy is a crucial concept within classical and quantum physics. An essential tool to quantify energy is the Hamiltonian. Here, we consider how to define a Hamiltonian in general probabilistic theories, a framework in which quantum theory is a special case. We list desiderata which the definition should meet. For 3-dimensional systems, we provide a fully-defined recipe which satisfies these desiderata. We discuss the higher dimensional case where some freedom of choice is left remaining. We apply the definition to example toy theories, and discuss how the quantum notion of time evolution as a phase between energy eigenstates generalises to other theories.Comment: Authors' accepted manuscript for inclusion in the Foundations of Physics topical collection on Foundational Aspects of Quantum Informatio

Binary and Millisecond Pulsars at the New Millennium

We review the properties and applications of binary and millisecond pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1300. There are now 56 binary and millisecond pulsars in the Galactic disk and a further 47 in globular clusters. This review is concerned primarily with the results and spin-offs from these surveys which are of particular interest to the relativity community.Comment: 59 pages, 26 figures, 5 tables. Accepted for publication in Living Reviews in Relativity (http://www.livingreviews.org

Differential Expression of Melanopsin Isoforms Opn4L and Opn4S during Postnatal Development of the Mouse Retina

Photosensitive retinal ganglion cells (pRGCs) respond to light from birth and represent the earliest known light detection system to develop in the mouse retina. A number of morphologically and functionally distinct subtypes of pRGCs have been described in the adult retina, and have been linked to different physiological roles. We have previously identified two distinct isoforms of mouse melanopsin, Opn4L and Opn4S, which are generated by alternate splicing of the Opn4 locus. These isoforms are differentially expressed in pRGC subtypes of the adult mouse retina, with both Opn4L and Opn4S detected in M1 type pRGCs, and only Opn4L detected in M2 type pRGCs. Here we investigate the developmental expression of Opn4L and Opn4S and show a differential profile of expression during postnatal development. Opn4S mRNA is detected at relatively constant levels throughout postnatal development, with levels of Opn4S protein showing a marked increase between P0 and P3, and then increasing progressively over time until adult levels are reached by P10. By contrast, levels of Opn4L mRNA and protein are low at birth and show a marked increase at P14 and P30 compared to earlier time points. We suggest that these differing profiles of expression are associated with the functional maturation of M1 and M2 subtypes of pRGCs. Based upon our data, Opn4S expressing M1 type pRGCs mature first and are the dominant pRGC subtype in the neonate retina, whereas increased expression of Opn4L and the maturation of M2 type pRGCs occurs later, between P10 and P14, at a similar time to the maturation of rod and cone photoreceptors. We suggest that the distinct functions associated with these cell types will develop at different times during postnatal development

Exploring the effects of telehealth on medical human resources supply: a qualitative case study in remote regions

BACKGROUND: The availability of medical human resource supply is a growing concern for rural and remote communities in many countries. In the last decade, various telehealth experiences in Canada have highlighted the potential impact of this technology on professional practice. The purpose of this study was to explore physicians' and managers' perceptions regarding the potential of telehealth to support recruitment and retention of physicians in remote and rural regions. METHODS: A case study in Eastern Quebec was performed to explore this complex phenomenon. The analytical framework was based on two literature reviews and a Delphi study. Data were collected from semi-structured interviews with 41 physicians and 22 managers. Transcripts were produced and interview content was coded independently by two judges and validated by an expert panel. RESULTS: Interviews have highlighted the potential impact of telehealth on several factors influencing the recruitment and retention of physicians in rural and remote regions. The potential effects of telehealth on physicians' choice of practice location could be seen at the professional, organizational, educational and individual levels. For instance, telehealth could improve work satisfaction by allowing a regional on-call duty system and a better follow-up of patients. However, there are also certain limits related to telehealth, such as the fear that it would eventually replace all continuing medical education activities and onsite specialists in remoteregions. CONCLUSION: Telehealth is likely to have an impact on several factors related to medical workforce supply in remote and rural regions. However, the expected benefits will materialize if and only if this technology is properly integrated into organizations as a support to professional practice

Biopsy-based calibration of T2* magnetic resonance for estimation of liver iron concentration and comparison with R2 Ferriscan.

BACKGROUND: There is a need to standardise non-invasive measurements of liver iron concentrations (LIC) so clear inferences can be drawn about body iron levels that are associated with hepatic and extra-hepatic complications of iron overload. Since the first demonstration of an inverse relationship between biopsy LIC and liver magnetic resonance (MR) using a proof-of-concept T2* sequence, MR technology has advanced dramatically with a shorter minimum echo-time, closer inter-echo spacing and constant repetition time. These important advances allow more accurate calculation of liver T2* especially in patients with high LIC. METHODS: Here, we used an optimised liver T2* sequence calibrated against 50 liver biopsy samples on 25 patients with transfusional haemosiderosis using ordinary least squares linear regression, and assessed the method reproducibility in 96 scans over an LIC range up to 42 mg/g dry weight (dw) using Bland-Altman plots. Using mixed model linear regression we compared the new T2*-LIC with R2-LIC (Ferriscan) on 92 scans in 54 patients with transfusional haemosiderosis and examined method agreement using Bland-Altman approach. RESULTS: Strong linear correlation between ln(T2*) and ln(LIC) led to the calibration equation LIC = 31.94(T2*)-1.014. This yielded LIC values approximately 2.2 times higher than the proof-of-concept T2* method. Comparing this new T2*-LIC with the R2-LIC (Ferriscan) technique in 92 scans, we observed a close relationship between the two methods for values up to 10 mg/g dw, however the method agreement was poor. CONCLUSIONS: New calibration of T2* against liver biopsy estimates LIC in a reproducible way, correcting the proof-of-concept calibration by 2.2 times. Due to poor agreement, both methods should be used separately to diagnose or rule out liver iron overload in patients with increased ferritin

Characteristics and management of HIV-1-infected pregnant women enrolled in a randomised trial: differences between Europe and the USA

<p>Abstract</p> <p>Background</p> <p>Rates of mother-to-child transmission of HIV-1 (MTCT) have historically been lower in European than in American cohort studies, possibly due to differences in population characteristics. The Pediatric AIDS Clinical Trials Group Protocol (PACTG) 316 trial evaluated the effectiveness of the addition of intrapartum/neonatal nevirapine in reducing MTCT in women already receiving antiretroviral prophylaxis. Participation of large numbers of pregnant HIV-infected women from the US and Western Europe enrolling in the same clinical trial provided the opportunity to identify and explore differences in their characteristics and in the use of non-study interventions to reduce MTCT.</p> <p>Methods</p> <p>In this secondary analysis, 1350 women were categorized according to enrollment in centres in the USA (n = 978) or in Europe (n = 372). Factors associated with receipt of highly active antiretroviral therapy and with elective caesarean delivery were identified with logistic regression.</p> <p>Results</p> <p>In Europe, women enrolled were more likely to be white and those of black race were mainly born in Sub-Saharan Africa. Women in the US were younger and more likely to have previous pregnancies and miscarriages and a history of sexually transmitted infections.</p> <p>More than 90% of women did not report symptoms of their HIV infection; however, more women from the US had symptoms (8%), compared to women from Europe (4%). Women in the US were less likely to have HIV RNA levels <400 copies/ml at delivery than women enrolling in Europe, and more likely to receive highly active antiretroviral therapy, and to start therapy earlier in pregnancy. The elective caesarean delivery rate in Europe was 61%, significantly higher than that in the US (22%). Overall, 1.48% of infants were infected and there was no significant difference in the rate of transmission between Europe and the US despite the different approaches to treatment and delivery.</p> <p>Conclusion</p> <p>These findings confirm that there are important historical differences between the HIV-infected pregnant populations in Western Europe and the USA, both in terms of the characteristics of the women and their obstetric and therapeutic management. Although highly active antiretroviral therapy predominates in pregnancy in both settings now, population differences are likely to remain.</p> <p>Trial registration</p> <p>NCT00000869</p

Binary and Millisecond Pulsars

We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1700. There are now 80 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 103 pulsars in 24 of the Galactic globular clusters. Recent highlights have been the discovery of the first ever double pulsar system and a recent flurry of discoveries in globular clusters, in particular Terzan 5.Comment: 77 pages, 30 figures, available on-line at http://www.livingreviews.org/lrr-2005-

Hybrid forward osmosis-membrane distillation system: demonstration of technical feasibility

The hybridisation of forward osmosis (FO) and membrane distillation (MD) has the potential to offer a solution to the increasing worldwide demand for clean water. However, accurate prediction of system behaviour, balancing of water transfer rates and the implementation of a suitable draw solution are needed to maximise permeate production. Currently, there is a lack of comprehensive mathematical tools available and further draw solution developments are required. In this study, an experimentally validated mathematical model was developed to simulate the FO-MD system. Draw solutes including sodium chloride (NaCl), tetraethylammonium bromide (TEAB) and polydiallyldimethylammonium chloride (PDAC), were used to characterise individual FO and MD permeate fluxes. The FO-MD system was then run using 0.5 M NaCl, TEAB and PDAC. The results showed that fouling was more significant in FO, and water transfer rate imbalances were identified in all systems. The experimental results and model were used to predict MD feed temperature and cross-flow velocity adjustments to achieve system water balance for each draw solution. As a result of this balancing, permeate production using NaCl, TEAB and PDAC was enhanced. This study suggests that the FO-MD system is a promising candidate for water purification when system performance is optimised through mathematical modelling

Seroepidemiology of Herpes Simplex virus type 1 and 2 in Western and Southern Switzerland in adults aged 25-74 in 1992-93: a population-based study.

BACKGROUND: Genital herpes is one of the most prevalent sexually-transmitted diseases, and accounts for a substantial morbidity. Genital herpes puts newborns at risk for very severe disease and also increases the risk of horizontal HIV transmission. It thus stands as an important public health problem. The recent availability of type-specific gG-based assays detecting IgG against HSV-1 and HSV-2 allows to establish the prevalence of each subtype. Worldwide, few data have been published regarding the seroprevalence in general populations of HSV-2, the major causative agent for genital herpes, while no data exist regarding the Swiss population. METHODS: To evaluate the prevalence of IgG antibodies against HSV-1 and HSV-2 in Switzerland, we used a population-based serum repository from a health examination survey conducted in the Western and Southern area of Switzerland in 1992-93. A total of 3,120 sera were analysed by type-specific gG-based ELISA and seroprevalence was correlated with available volunteers characteristics by logistic regression. RESULTS: Overall, seroprevalence rates were 80.0 +/- 0.9% (SE, 95% CI: 78.1-81.8) for HSV-1 and 19.3 +/- 0.9% (SE, 95% CI: 17.6-21.1) for HSV-2 in adults 35-64 year old. HSV-1 and HSV-2 seroprevalence increased with age, with a peak HSV-2 seroprevalence in elderly gentlemen, possibly a seroarcheological evidence of sexually transmitted disease epidemics during World War II. Risk factors for HSV-2 infection included female sex, marital status other than married, and size of town of residence larger than 1500 inhabitants. Unexpectedly and conversely to HSV-1, HSV-2 seroprevalence increased with educational level. HSV-2 infection was less prevalent among HSV-1 infected individuals when compared to HSV-1 uninfected individuals. This effect was most apparent among women at high risk for HSV-2 infection. CONCLUSIONS: Our data demonstrate that by the early nineties, HSV-2 had spread quite largely in the Swiss population. However, the epidemiology of HSV-2 in Switzerland presents paradoxical characteristics, e.g. positive correlation with education level, that have not been observed elsewhere