Safe-Play Knowledge, Aggression, and Head-Impact Biomechanics in Adolescent Ice Hockey Players

Addressing safe-play knowledge and player aggression could potentially improve ice hockey sport safety

Endogenous Jurisprudential Regimes

Jurisprudential regime theory is a legal explanation of decision-making on the U.S. Supreme Court that asserts that a key precedent in an area of law fundamentally restructures the relationship between case characteristics and the outcomes of future cases. In this article, we offer a multivariate multiple change-point probit model that can be used to endogenously test for the existence of jurisprudential regimes. Unlike the previously employed methods, our model does so by estimating the locations of many possible changepoints along with structural parameters. We estimate the model using Markov chain Monte Carlo methods, and use Bayesian model comparison to determine the number of change-points. Our findings are consistent with jurisprudential regimes in the Establishment Clause and administrative law contexts. We find little support for hypothesized regimes in the areas of free speech and search-and-seizure. The Bayesian multivariate change-point model we propose has broad potential applications to studying structural breaks in either regular or irregular time-series data about political institutions or processes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116095/1/pa12.pd

AEGIS: New Evidence Linking Active Galactic Nuclei to the Quenching of Star Formation

Utilizing Chandra X-ray observations in the All-wavelength Extended Groth Strip International Survey (AEGIS) we identify 241 X-ray selected Active Galactic Nuclei (AGNs, L > 10^{42} ergs/s) and study the properties of their host galaxies in the range 0.4 < z < 1.4. By making use of infrared photometry from Palomar Observatory and BRI imaging from the Canada-France-Hawaii Telescope, we estimate AGN host galaxy stellar masses and show that both stellar mass and photometric redshift estimates (where necessary) are robust to the possible contamination from AGNs in our X-ray selected sample. Accounting for the photometric and X-ray sensitivity limits of the survey, we construct the stellar mass function of X-ray selected AGN host galaxies and find that their abundance decreases by a factor of ~2 since z~1, but remains roughly flat as a function of stellar mass. We compare the abundance of AGN hosts to the rate of star formation quenching observed in the total galaxy population. If the timescale for X-ray detectable AGN activity is roughly 0.5-1 Gyr--as suggested by black hole demographics and recent simulations--then we deduce that the inferred AGN "trigger" rate matches the star formation quenching rate, suggesting a link between these phenomena. However, given the large range of nuclear accretion rates we infer for the most massive and red hosts, X-ray selected AGNs may not be directly responsible for quenching star formation.Comment: 12 pages. Submitted to ApJ. Comments welcom

Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers

We present the results from a Chandra pilot study of 12 massive galaxy mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 10$^{11}$ $M_\odot$ that already have optical AGN signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured ($N_H \lesssim 1.1 \times 10^{22}$ cm$^{-2}$) X-ray nuclei are relatively common (8/12), but the detections are too faint ($< 40$ counts per nucleus; $f_{2-10 keV} \lesssim 1.2 \times 10^{-13}$ erg s$^{-1}$ cm$^{-2}$) to reliably separate starburst and nuclear activity as the origin of the X-ray emission. Only one merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGN in these mergers are rare (0-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.Comment: 8 pages, including 5 figures and 1 table. Accepted by Ap

Incremental benefit in correlation with histology of native T1 mapping, partition coefficient and extracellular volume fraction in patients with aortic stenosis

Background: We investigated the histological correlation of native T1 maps, partition coefficient and extracellular volume fraction (ECV) using an 11 heart beat (11 HB) MOLLI for identification of overall burden of fibrosis. Methods: Ten patients (8 male, age 73 ± 7 years; all in sinus rhythm, 2 with ventricular ectopy) with severe aortic stenosis (3 with coexisting coronary artery disease) scheduled for surgical aortic valve replacement underwent CMR on a 1.5T scanner (MAGNETOM Avanto, Siemens Healthcare, Erlangen). The 11HB MOLLI sequence (Siemens investigational prototype WIP 448B) was acquired before and 15 minutes post 0.1 mmol/kg gadolinium administration. Incorporating hematocrit results from the same day. This allowed native T1 maps, partition coefficient and ECV calculation. Images were obtained twice at end diastole at basal, and twice at mid left ventricular level. The average of all measurements was used to calculate ECV using the standard formula Partition Coefficient= [(1/T1myocardium post contrast-1/T1 myocardium native)]/[(1/T1 blood post contrast-1/T1 blood native)] with x(1-HCt) for ECV. Similar regions of interest were drawn in the septum at both levels for T1 values. Intraoperatively, trucut biopsies were taken from the left ventricular apical anterior/ lateral wall through the epicardium to allow histological characterization of the full myocardial wall, and fixed in warm buffered formalin. Histological analysis of formalin-fixed paraffin-embedded, transmural myocardial biopsies of the left ventricle was performed on hematoxylin/eosin and Picrosirius red-stained 3-micron-thick sections by a blinded experienced cardiac pathologist. Images were analysed using a purpose-built software (Nikon NIS elements BR) on a NIKON Eclipse light projection microscope to determine the extent of overall and reactive interstitial fibrosis, which was expressed as collagen volume fraction (%) per square millimetre. Results: Native T1 mapping, partition coefficient and ECV all correlated with histologically measured fibrosis. However, native T1 mapping showed the least accuracy (panel A, R2 = 0.42) and ECV showed the highest accuracy (panel B, R2 = 0.83). Partition coefficient was more accurate than native T1 mapping but only very marginally less so than ECV (panel C, R2 = 0.80). Conclusions: These results suggest that native T1 mapping is less accurate than partition coefficient and ECV for overall fibrosis. Therefore, post gadolinium images to enable calculation of partition coefficient and ECV should be routinely obtained to increase accuracy

Rabies screen reveals GPe control of cocaine-triggered plasticity.

Identification of neural circuit changes that contribute to behavioural plasticity has routinely been conducted on candidate circuits that were preselected on the basis of previous results. Here we present an unbiased method for identifying experience-triggered circuit-level changes in neuronal ensembles in mice. Using rabies virus monosynaptic tracing, we mapped cocaine-induced global changes in inputs onto neurons in the ventral tegmental area. Cocaine increased rabies-labelled inputs from the globus pallidus externus (GPe), a basal ganglia nucleus not previously known to participate in behavioural plasticity triggered by drugs of abuse. We demonstrated that cocaine increased GPe neuron activity, which accounted for the increase in GPe labelling. Inhibition of GPe activity revealed that it contributes to two forms of cocaine-triggered behavioural plasticity, at least in part by disinhibiting dopamine neurons in the ventral tegmental area. These results suggest that rabies-based unbiased screening of changes in input populations can identify previously unappreciated circuit elements that critically support behavioural adaptations

Synthesis and anticancer activity of novel bisindolylhydroxymaleimide derivatives with potent GSK-3 kinase inhibition

Synthesis and biological evaluation of a series of novel indole derivatives as anticancer agents is described. A bisindolylmaleimide template has been derived as a versatile pharmacophore with which to pursue chemical diversification. Starting from maleimide, the introduction of an oxygen to the headgroup (hydroxymaleimide) was initially investigated and the bioactivity assessed by screening of kinase inhibitory activity, identifying substituent derived selectivity. Extension of the hydroxymaleimide template to incorporate substitution of the indole nitrogens was next completed and assessed again by kinase inhibition identifying unique selectivity patterns with respect to GSK-3 and CDK kinases. Subsequently, the anticancer activity of bisindolylmaleimides were assessed using the NCI-60 cell screen, disclosing the discovery of growth inhibitory profiles towards a number of cell lines, such as SNB-75 CNS cancer, A498 and UO-31 renal, MDA MB435 melanoma and a panel of leukemia cell lines. The potential for selective kinase inhibition by modulation of this template is evident and will inform future selective clinical candidates