A Competition Perspective on Physician Non-compete Agreements.

Physician non-compete agreements may have significant competitive implications, and effects on both providers and patients, but they are treated variously under the law on a state-by-state basis. Reviewing the relevant law and the economic literature cannot identify with confidence the net effects of such agreements on either physicians or health care delivery with any generality. In addition to identifying future research projects to inform policy, it is argued that the antitrust "rule of reason" provides a useful and established framework with which to evaluate such agreements in specific health care markets and, potentially, to address those agreements most likely to do significant damage to health care competition and consumers.

Pushing the limits of detectability: mixed dark matter from strong gravitational lenses.

One of the frontiers for advancing what is known about dark matter lies in using strong gravitational lenses to characterize the population of the smallest dark matter haloes. There is a large volume of information in strong gravitational lens images - the question we seek to answer is to what extent we can refine this information. To this end, we forecast the detectability of a mixed warm and cold dark matter scenario using the anomalous flux ratio method from strong gravitational lensed images. The halo mass function of the mixed dark matter scenario is suppressed relative to cold dark matter but still predicts numerous low-mass dark matter haloes relative to warm dark matter. Since the strong lensing signal receives a contribution from a range of dark matter halo masses and since the signal is sensitive to the specific configuration of dark matter haloes, not just the halo mass function, degeneracies between different forms of suppression in the halo mass function, relative to cold dark matter, can arise. We find that, with a set of lenses with different configurations of the main deflector and hence different sensitivities to different mass ranges of the halo mass function, the different forms of suppression of the halo mass function between the warm dark matter model and the mixed dark matter model can be distinguished with 40 lenses with Bayesian odds of 30:1.

Constraints on the Hubble constant from supernova Refsdal's reappearance.

The gravitationally lensed supernova Refsdal appeared in multiple images produced through gravitational lensing by a massive foreground galaxy cluster. After the supernova appeared in 2014, lens models of the galaxy cluster predicted that an additional image of the supernova would appear in 2015, which was subsequently observed. We use the time delays between the images to perform a blinded measurement of the expansion rate of the Universe, quantified by the Hubble constant (H0). Using eight cluster lens models, we infer [Formula: see text]. Using the two models most consistent with the observations, we find [Formula: see text]. The observations are best reproduced by models that assign dark-matter halos to individual galaxies and the overall cluster.

Constraints on Sterile Neutrino Models from Strong Gravitational Lensing, Milky Way Satellites, and the Lyman-α Forest.

The nature of dark matter is one of the most important unsolved questions in science. Some darkf matter candidates do not have sufficient nongravitational interactions to be probed in laboratory or accelerator experiments. It is thus important to develop astrophysical probes which can constrain or lead to a discovery of such candidates. We illustrate this using state-of-the-art measurements of strong gravitationally lensed quasars to constrain four of the most popular sterile neutrino models, and also report the constraints for other independent methods that are comparable in procedure. First, we derive effective relations to describe the correspondence between the mass of a thermal relic warm dark matter particle and the mass of sterile neutrinos produced via Higgs decay and grand unified theory (GUT)-scale scenarios, in terms of large-scale structure and galaxy formation astrophysical effects. Second, we show that sterile neutrinos produced through the Higgs decay mechanism are allowed only for mass >26 keV, and GUT-scale scenario >5.3 keV. Third, we show that the single sterile neutrino model produced through active neutrino oscillations is allowed for mass >92 keV, and the three sterile neutrino minimal standard model (νMSM) for mass >16 keV. These are the most stringent experimental limits on these models.

Identification of current priorities for research in humanitarian action: proceedings of the First Annual UN OCHA Policy and Research Conference.

On December 12-13, 2011, the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) hosted a humanitarian policy and research conference on the theme of "Risk, Adaptation and Innovation in Humanitarian Action." The four sessions of the conference covered humanitarian action in a changing world, adaptation and innovation in humanitarian action, humanitarian action in protracted and violent conflict, and effective humanitarian action. This special report contains summaries of presentations in each session and the conclusions resulting from the discussions throughout. Through a process of open discussion, debate, and a closing survey, the conference participants identified four top priorities in humanitarian research for the coming years: evidence-driven humanitarian decision-making; accountability and transparency; risk and agility; and partnership. In addition to plans for a 2nd Annual Research and Policy conference in December of 2012, specific outcomes of the conference include a series of regional workshops in 2012 and 2013, launching with Asia, Africa and the Middle East; creation of Policy Working Groups (PWG) for each research priority identified; and a new flagship OCHA publication, to be launched in late 2012 or early 2013, which will share the progress made on the research priorities identified.