The English are healthier than the Americans: really?

Background: When comparing the health of two populations, it is not enough to compare the prevalence of chronic diseases. The objective of this study is therefore to propose a metric of health based on domains of functioning to determine whether the English are healthier than the Americans. Methods: We analysed representative samples aged 50 to 80 years from the 2008 wave of the Health and Retirement Study (N?=?10?349) for the US data, and wave 4 of the English Longitudinal Study of Ageing (N?=?9405) for English counterpart data. We first calculated the age-standardized disease prevalence of diabetes, hypertension, all heart diseases, stroke, lung disease, cancer and obesity. Second, we developed a metric of health using Rasch analyses and the questions and measured tests common to both surveys addressing domains of human functioning. Finally, we used a linear additive model to test whether the differences in health were due to being English or American. Results: The English have better health than the Americans when population health is assessed only by prevalence of selected chronic health conditions. The English health advantage disappears almost completely, however, when health is assessed with a metric that integrates information about functioning domains. Conclusions: It is possible to construct a metric of health, based on data directly collected from individuals, in which health is operationalized as domains of functioning. Its application has the potential to tackle one of the most intractable problems in international research on health, namely the comparability of health across countries

Computation with narrow CTCs

We examine some variants of computation with closed timelike curves (CTCs), where various restrictions are imposed on the memory of the computer, and the information carrying capacity and range of the CTC. We give full characterizations of the classes of languages recognized by polynomial time probabilistic and quantum computers that can send a single classical bit to their own past. Such narrow CTCs are demonstrated to add the power of limited nondeterminism to deterministic computers, and lead to exponential speedup in constant-space probabilistic and quantum computation. We show that, given a time machine with constant negative delay, one can implement CTC-based computations without the need to know about the runtime beforehand.Comment: 16 pages. A few typo was correcte

High pressure diamond-like liquid carbon

We report density-functional based molecular dynamics simulations, that show that, with increasing pressure, liquid carbon undergoes a gradual transformation from a liquid with local three-fold coordination to a 'diamond-like' liquid. We demonstrate that this unusual structural change is well reproduced by an empirical bond order potential with isotropic long range interactions, supplemented by torsional terms. In contrast, state-of-the-art short-range bond-order potentials do not reproduce this diamond structure. This suggests that a correct description of long-range interactions is crucial for a unified description of the solid and liquid phases of carbon.Comment: 4 pages, 5 figure

A meta-analysis of genome-wide association studies of growth differentiation Factor-15 concentration in blood

Blood levels of growth differentiation factor-15 (GDF-15), also known as macrophage inhibitory cytokine-1 (MIC-1), have been associated with various pathological processes and diseases, including cardiovascular disease and cancer. Prior studies suggest genetic factors play a role in regulating blood MIC-1/GDF-15 concentration. In the current study, we conducted the largest genome-wide association study (GWAS) to date using a sample of ∼5,400 community-based Caucasian participants, to determine the genetic variants associated with MIC-1/GDF-15 blood concentration. Conditional and joint (COJO), gene-based association, and gene-set enrichment analyses were also carried out to identify novel loci, genes, and pathways. Consistent with prior results, a locus on chromosome 19, which includes nine single nucleotide polymorphisms (SNPs) (top SNP, rs888663, p = 1.690 × 10-35), was significantly associated with blood MIC-1/GDF-15 concentration, and explained 21.47% of its variance. COJO analysis showed evidence for two independent signals within this locus. Gene-based analysis confirmed the chromosome 19 locus association and in addition, a putative locus on chromosome 1. Gene-set enrichment analyses showed that the“COPI-mediated anterograde transport” gene-set was associated with MIC-1/GDF15 blood concentration with marginal significance after FDR correction (p = 0.067). In conclusion, a locus on chromosome 19 was associated with MIC-1/GDF-15 blood concentration with genome-wide significance, with evidence for a new locus (chromosome 1). Future studies using independent cohorts are needed to confirm the observed associations especially for the chromosomes 1 locus, and to further investigate and identify the causal SNPs that contribute to MIC-1/GDF-15 levels

Impact of lameness and claw lesions in cows on health and production

Lameness is one of the most important endemic diseases of cattle, particularly in the dairy sector. It has a significant impact on health and welfare and leads to a range of production losses. This article reviews the English language peer reviewed literature on the impacts of lameness in cattle on measures of health and production. There is a wealth of evidence from around the world demonstrating that lameness reduces milk yield. The extent of the reductions identified is difficult to summarise, however when losses have been calculated across a whole lactation, most are between 270 and 574kg. It is noteworthy that there is now strong evidence that lameness is a disease of high milk production i.e. high yielding animals are more likely to become lame. The impacts of lameness on nutrition and body condition appear complex. Overall the literature suggests that lameness leads to a reduction in the time spent feeding. A positive correlation between low body condition score and lameness has been demonstrated in a range of studies. Historically it was considered that lame cows lost weight as a consequence of the largely negative impacts of disease, on nutrition. Increasingly, evidence is appearing which suggests that the association between body condition score and lameness may in fact be the other way around i.e. high yielding cows which loose body condition during periods of negative energy balance become lame. The effect of lameness on fertility, measured in studies from around the world, is unequivocal. Lameness has substantial negative effects on fertility performance and reproductive parameters across a wide range of areas. Evidence on the association between lameness and culling is mixed. The majority of published work suggests that animals which suffer from lameness are more likely to be culled, although the converse has also been demonstrated. A review of the literature in this area demonstrates just how substantial the negative effects of lameness are on cattle health and production. The impacts are wide ranging and significant from both a welfare and an economic performance perspective. Further work is urgently required to control this important and prevalent condition

Star Formation and Dynamics in the Galactic Centre

The centre of our Galaxy is one of the most studied and yet enigmatic places in the Universe. At a distance of about 8 kpc from our Sun, the Galactic centre (GC) is the ideal environment to study the extreme processes that take place in the vicinity of a supermassive black hole (SMBH). Despite the hostile environment, several tens of early-type stars populate the central parsec of our Galaxy. A fraction of them lie in a thin ring with mild eccentricity and inner radius ~0.04 pc, while the S-stars, i.e. the ~30 stars closest to the SMBH (<0.04 pc), have randomly oriented and highly eccentric orbits. The formation of such early-type stars has been a puzzle for a long time: molecular clouds should be tidally disrupted by the SMBH before they can fragment into stars. We review the main scenarios proposed to explain the formation and the dynamical evolution of the early-type stars in the GC. In particular, we discuss the most popular in situ scenarios (accretion disc fragmentation and molecular cloud disruption) and migration scenarios (star cluster inspiral and Hills mechanism). We focus on the most pressing challenges that must be faced to shed light on the process of star formation in the vicinity of a SMBH.Comment: 68 pages, 35 figures; invited review chapter, to be published in expanded form in Haardt, F., Gorini, V., Moschella, U. and Treves, A., 'Astrophysical Black Holes'. Lecture Notes in Physics. Springer 201

Scale-free static and dynamical correlations in melts of monodisperse and Flory-distributed homopolymers: A review of recent bond-fluctuation model studies

It has been assumed until very recently that all long-range correlations are screened in three-dimensional melts of linear homopolymers on distances beyond the correlation length $\xi$ characterizing the decay of the density fluctuations. Summarizing simulation results obtained by means of a variant of the bond-fluctuation model with finite monomer excluded volume interactions and topology violating local and global Monte Carlo moves, we show that due to an interplay of the chain connectivity and the incompressibility constraint, both static and dynamical correlations arise on distances $r \gg \xi$. These correlations are scale-free and, surprisingly, do not depend explicitly on the compressibility of the solution. Both monodisperse and (essentially) Flory-distributed equilibrium polymers are considered.Comment: 60 pages, 49 figure