Autocracy, democracy, bureaucracy, or monopoly: can you judge a government by its size?

We develop a simple theoretical framework to examine on an integrated basis how the form of government affects its power and size. The analytical framework abstracts from distortions that arise from the means ofgovernment finance and separates government power into two dimensions-pure coercive power and pure monopoly power. A government can exert its coercive power to shift the demand for its services outward and/or its monopoly power to restrict the output along a given demand curve to earn rents. Among the implications drawn from the analysis are that government officials have an incentive to provide a non-optimal combination of taxes and services, and that neither size nor rents alone are reliable indicators of the extent to which government fails to achieve optimality in its provision of services.Finance ; Power resources

Interferometric data for a shock-wave/boundary-layer interaction

An experimental study of the axisymmetric shock-wave / boundary-layer strong interaction flow generated in the vicinity of a cylinder-cone intersection was conducted. The study data are useful in the documentation and understanding of compressible turbulent strong interaction flows, and are part of a more general effort to improve turbulence modeling for compressible two- and three-dimensional strong viscous/inviscid interactions. The nominal free stream Mach number was 2.85. Tunnel total pressures of 1.7 and 3.4 atm provided Reynolds number values of 18 x 10(6) and 36 x 10(6) based on model length. Three cone angles were studied giving negligible, incipient, and large scale flow separation. The initial cylinder boundary layer upstream of the interaction had a thickness of 1.0 cm. The subsonic layer of the cylinder boundary layer was quite thin, and in all cases, the shock wave penetrated a significant portion of the boundary layer. Owing to the thickness of the cylinder boundary layer, considerable structural detail was resolved for the three shock-wave / boundary-layer interaction cases considered. The primary emphasis was on the application of the holographic interferometry technique. The density field was deduced from an interferometric analysis based on the Able transform. Supporting data were obtained using a 2-D laser velocimeter, as well as mean wall pressure and oil flow measurements. The attached flow case was observed to be steady, while the separated cases exhibited shock unsteadiness. Comparisons with Navier-Stokes computations using a two-equation turbulence model are presented

When can gravitational-wave observations distinguish between black holes and neutron stars?

Gravitational-wave observations of compact binaries have the potential to uncover the distribution of masses and angular momenta of black holes and neutron stars in the universe. The binary components' physical parameters can be inferred from their effect on the phasing of the gravitational-wave signal, but a partial degeneracy between the components' mass ratio and their angular momenta limits our ability to measure the individual component masses. At the typical signal amplitudes expected by the Advanced Laser Interferometer Gravitational-wave Observatory (signal-to-noise ratios between 10 and 20), we show that it will in many cases be difficult to distinguish whether the components are neutron stars or black holes. We identify when the masses of the binary components could be unambiguously measured outside the range of current observations: a system with a chirp mass $\mathcal{M} \le 0.871$ M$_\odot$ would unambiguously contain the smallest-mass neutron star observed, and a system with \mathcal{M} \ge 2.786 \Msun must contain a black hole. However, additional information would be needed to distinguish between a binary containing two 1.35 M$_\odot$ neutron stars and an exotic neutron-star--black-hole binary. We also identify those configurations that could be unambiguously identified as black-hole binaries, and show how the observation of an electromagnetic counterpart to a neutron-star--black-hole binary could be used to constrain the black-hole spin.Comment: 5 pages, 4 figures. Final version to be published in Ap.J.Let

Gender and school-level differences in students' moderate and vigorous physical activity levels when taught basketball through the tactical games model

The Tactical Games Model (TGM) prefaces the cognitive components of physical education (PE), which has implications for physical activity (PA) accumulation. PA recommendations suggest students reach 50% moderate-vigorous physical activity (MVPA). However, this criterion does not indicate the contribution from vigorous physical activity (VPA). Consequently, this study investigated: a) the effects of TGM delivery on MVPA/VPA and, b) gender/school level differences. Participants were 78 seventh and 96 fourth/fifth grade coeducational PE students from two different schools. Two teachers taught 24 (middle) and 30 (elementary) level one TGM basketball lessons. Students wore Actigraph GT3× triaxial accelerometers. Data were analyzed using four one-way ANOVAs. Middle school boys had significantly higher MVPA/VPA (34.04/22.37%) than girls (25.14/15.47%). Elementary school boys had significantly higher MVPA/VPA (29.73/18.33%) than girls (23.03/14.33%). While TGM lessons provide a context where students can accumulate VPA consistent with national PA recommendations, teachers need to modify lesson activities to enable equitable PA participation

The Warwick-Edinburgh Mental Well-being Scale (WEMWBS) : development and UK validation

Background There is increasing international interest in the concept of mental well-being and its contribution to all aspects of human life. Demand for instruments to monitor mental well-being at a population level and evaluate mental health promotion initiatives is growing. This article describes the development and validation of a new scale, comprised only of positively worded items relating to different aspects of positive mental health: the Warwick-Edinburgh Mental Well-Being Scale (WEMWBS). Methods WEMWBS was developed by an expert panel drawing on current academic literature, qualitative research with focus groups, and psychometric testing of an existing scale. It was validated on a student and representative population sample. Content validity was assessed by reviewing the frequency of complete responses and the distribution of responses to each item. Confirmatory factor analysis was used to test the hypothesis that the scale measured a single construct. Internal consistency was assessed using Cronbach's alpha. Criterion validity was explored in terms of correlations between WEMWBS and other scales and by testing whether the scale discriminated between population groups in line with pre-specified hypotheses. Test-retest reliability was assessed at one week using intra-class correlation coefficients. Susceptibility to bias was measured using the Balanced Inventory of Desired Responding. Results WEMWBS showed good content validity. Confirmatory factor analysis supported the single factor hypothesis. A Cronbach's alpha score of 0.89 (student sample) and 0.91 (population sample) suggests some item redundancy in the scale. WEMWBS showed high correlations with other mental health and well-being scales and lower correlations with scales measuring overall health. Its distribution was near normal and the scale did not show ceiling effects in a population sample. It discriminated between population groups in a way that is largely consistent with the results of other population surveys. Test-retest reliability at one week was high (0.83). Social desirability bias was lower or similar to that of other comparable scales. Conclusion WEMWBS is a measure of mental well-being focusing entirely on positive aspects of mental health. As a short and psychometrically robust scale, with no ceiling effects in a population sample, it offers promise as a tool for monitoring mental well-being at a population level. Whilst WEMWBS should appeal to those evaluating mental health promotion initiatives, it is important that the scale's sensitivity to change is established before it is recommended in this context

Fibonacci Powers and a Fascinating Triangle

The well-known Fibonacci sequence can be used as a starting pint for an interesting project or research experience for a discrete mathematics class

Human sperm ion channel (dys)function:implications for fertilization

BACKGROUND: Intensive research on sperm ion channels has identified members of several ion channel families in both mouse and human sperm. Gene knock-out studies have unequivocally demonstrated the importance of the calcium and potassium conductances in sperm for fertility. In both species, the calcium current is carried by the highly complex cation channel of sperm (CatSper). In mouse sperm, the potassium current has been conclusively shown to be carried by a channel consisting of the pore forming subunit SLO3 and auxiliary subunit leucine-rich repeat-containing 52 (LRRC52). However, in human sperm it is controversial whether the pore forming subunit of the channel is composed of SLO3 and/or SLO1. Deciphering the role of the proton-specific Hv1 channel is more challenging as it is only expressed in human sperm. However, definitive evidence for a role in, and importance for, human fertility can only be determined through studies using clinical samples.OBJECTIVE AND RATIONALE: This review aims to provide insight into the role of sperm ion channels in human fertilization as evidenced from recent studies of sperm from infertile men. We also summarize the key discoveries from mouse ion channel knock-out models and contrast the properties of mouse and human CatSper and potassium currents. We detail the evidence for, and consequences of, defective ion channels in human sperm and discuss hypotheses to explain how defects arise and why affected sperm have impaired fertilization potential.SEARCH METHODS: Relevant studies were identified using PubMed and were limited to ion channels that have been characterized in mouse and human sperm. Additional notable examples from other species are included as appropriate.OUTCOMES: There are now well-documented fundamental differences between the properties of CatSper and potassium channel currents in mouse and human sperm. However, in both species, sperm lacking either channel cannot fertilize in vivo and CatSper-null sperm also fail to fertilize at IVF. Sperm-lacking potassium currents are capable of fertilizing at IVF, albeit at a much lower rate. However, additional complex and heterogeneous ion channel dysfunction has been reported in sperm from infertile men, the causes of which are unknown. Similarly, the nature of the functional impairment of affected patient sperm remains elusive. There are no reports of studies of Hv1 in human sperm from infertile men.WIDER IMPLICATIONS: Recent studies using sperm from infertile men have given new insight and critical evidence supporting the supposition that calcium and potassium conductances are essential for human fertility. However, it should be highlighted that many fundamental questions remain regarding the nature of molecular and functional defects in sperm with dysfunctional ion channels. The development and application of advanced technologies remains a necessity to progress basic and clinical research in this area, with the aim of providing effective screening methodologies to identify and develop treatments for affected men in order to help prevent failed ART cycles. Conversely, development of drugs that block calcium and/or potassium conductances in sperm is a plausible strategy for producing sperm-specific contraceptives.</p

HEDGE FUND DUE DILIGENCE: A SOURCE OF ALPHA IN A HEDGE FUND PORTFOLIO STRATEGY

Due diligence is an important source of alpha in a well designed hedge fund portfolio strategy. It is generally understood that the high returns possible in investing in hedge funds are somewhat offset by the relative lack of transparency on operational issues. The performance of a diversified hedge fund portfolio can be enhanced by excluding those funds likely to do poorly – or fail – due to operational risk concerns. However, effective due diligence is an expensive concern. This implies that there is a strong competitive advantage to those funds of funds sufficiently large to absorb this fixed and necessary cost. The consequent economies of scale that we document in funds of funds are quite substantial and support the proposition that due diligence is a source of alpha in hedge fund investment