SN 1996cr: Confirmation of a Luminous Type IIn Supernova in the Circinus Galaxy

We have recently confirmed SN 1996cr as a late-time type IIn supernova (SN) via VLT spectroscopy and isolated its explosion date to ~1 yr using archival optical imaging. We briefly touch upon here the wealth of optical, X-ray, and radio archival observations available for this enigmatic source. Due to its relative proximity (3.8 +/-0.6 Mpc), SN 1996cr ranks among the brightest X-ray and radio SNe ever detected and, as such, may offer powerful insights into the structure and composition of type IIn SNe. We also find that SN 1996cr is matched to GRB 4B 960202 at a 2-3 sigma confidence level, making it perhaps the third GRB to be significantly associated with a type II SN. We speculate on whether SN 1996cr could be an off-axis or ``failed'' GRB.Comment: 3 pages, 1 figure, poster proceeding for "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S. Immler, K.W. Weiler, and R. McCra

Physical activity education in the undergraduate curricula of all UK medical schools: are tomorrow's doctors equipped to follow clinical guidelines?

Physical activity (PA) is a cornerstone of disease prevention and treatment. There is, however, a considerable disparity between public health policy, clinical guidelines and the delivery of physical activity promotion within the National Health Service in the UK. If this is to be addressed in the battle against non-communicable diseases, it is vital that tomorrow's doctors understand the basic science and health benefits of physical activity. The aim of this study was to assess the provision of physical activity teaching content in the curricula of all medical schools in the UK. Our results, with responses from all UK medical schools, uncovered some alarming findings, showing that there is widespread omission of basic teaching elements, such as the Chief Medical Officer recommendations and guidance on physical activity. There is an urgent need for physical activity teaching to have dedicated time at medical schools, to equip tomorrow's doctors with the basic knowledge, confidence and skills to promote physical activity and follow numerous clinical guidelines that support physical activity promotion

Update on tests of the Cen A neutron-emission model of highest energy cosmic rays

We propose that neutron emission from Cen A dominates the cosmic ray sky at the high end of the spectrum. Neutrons that are able to decay generate proton diffusion fronts, whereas those that survive decay produce a spike in the direction of the source. We use recent data reported by the Pierre Auger Collaboration to normalize the injection spectrum and estimate the required luminosity in cosmic rays. We find that such a luminosity, L_{CR} ~ 5 x 10^{40} erg/s, is considerably smaller than the bolometric luminosity of Cen A, L_{bol} ~ 10^{43} erg/s. We compute the incoming current flux density as viewed by an observer on Earth and show that the anisotropy amplitude is in agreement with data at the 1\sigma level. Regardless of the underlying source model, our results indicate that after a decade of data taking the Pierre Auger Observatory will be able to test our proposal.Comment: To be published in PR

Why Groups Are Politically Active: An Incentive-Theoretical Approach

This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this recordPolitical activity is conventionally considered a constitutive feature of interest groups, underpinning an impressive literature on the strategies groups employ to exercise political influence. Whether and how intensely voluntary membership groups engage in political activities to start with, however, is rarely examined. We present a new incentive-theoretical perspective on group political activity, considering both member demands and leadership constraints. We argue that investments in political activities (one way of generating collective incentives) as a means to prevent member exit are more or less important depending on a group’s composition. Simultaneously, the extent to which leaders are incentivized to cater to members’ demands when trying to balance these against conflicting demands, depends on communication channels between leaders and members and the importance of membership fees. Applying Bayesian ordered logit models to data from two group surveys supports our perspective and stresses the importance of considering how intra-organizational dynamics steer groups’ external activities

Nucleosynthesis in Core-Collapse Supernovae and GRB--Metal-Poor Star Connection

We review the nucleosynthesis yields of core-collapse supernovae (SNe) for various stellar masses, explosion energies, and metallicities. Comparison with the abundance patterns of metal-poor stars provides excellent opportunities to test the explosion models and their nucleosynthesis. We show that the abundance patterns of extremely metal-poor (EMP) stars, e.g., the excess of C, Co, Zn relative to Fe, are in better agreement with the yields of hyper-energetic explosions (Hypernovae, HNe) rather than normal supernovae. We note that the variation of the abundance patterns of EMP stars are related to the diversity of the Supernova-GRB connection. We summarize the diverse properties of (1) GRB-SNe, (2) Non-GRB HNe/SNe, (3) XRF-SN, and (4) Non-SN GRB. In particular, the Non-SN GRBs (dark hypernovae) have been predicted in order to explain the origin of C-rich EMP stars. We show that these variations and the connection can be modeled in a unified manner with the explosions induced by relativistic jets. Finally, we examine whether the most luminous supernova 2006gy can be consistently explained with the pair-instability supernova model.Comment: 15 pages, 9 figures. To appear in "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters", eds. S. Immler, K. Weiler, & R. McCray (American Institute of Physics) (2007

Recent Type II Radio Supernovae

We present the results of radio observations, taken primarily with the Very Large Array, of Supernovae 1993J, 2001gd, 2001em, 2002hh, 2004dj, and 2004et. We have fit a parameterized model to the multi-frequency observations of each supernova. We compare the observed and derived radio properties of these supernovae by optical classification and discuss the implications.Comment: 5 pages, 2 figures, 1 table Conference Proceedings: "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S. Immler, K.W. Weiler, and R. McCra

Radiative neutrino decay and CP-violation in R-parity violating supersymmetry

We calculate the radiative decay amplitude for Majorana neutrinos in trilinear R-parity violating supersymmetric framework. Our results make no assumption regarding the masses and mixings of fermions and sfermions. The results obtained are exemplary for generic models with loop-generated neutrino masses. Comparison of this amplitude with the neutrino mass matrix shows that the two provide independent probes of CP-violating phases.Comment: Latex, uses axodraw, 14 pages (small changes implemented

Searching for Dark Matter at the LHC with a Mono-Z

We investigate a mono-Z process as a potential dark matter search strategy at the LHC. In this channel a single Z boson recoils against missing transverse momentum, attributed to dark matter particles, $\chi$, which escape the detector. This search strategy is related, and complementary to, monojet and monophoton searches. For illustrative purposes we consider the process $q\bar{q} -> \chi\chi Z$ in a toy dark matter model, where the Z boson is emitted from either the initial state quarks, or from the internal propagator. Among the signatures of this process will be a pair of muons with high pT that reconstruct to the invariant mass of the Z, and large amounts of missing transverse energy. Being a purely electroweak signal, QCD and other Standard Model backgrounds are relatively easily removed with modest selection cuts. We compare the signal to Standard Model backgrounds and demonstrate that, even for conservative cuts, there exist regions of parameter space where the signal may be clearly visible above background in future LHC data, allowing either new discovery potential or the possibility of supplementing information about the dark sector beyond that available from other observable channels.Comment: 11 pages, 13 figure