Modified Friedmann equations via conformal Bohm -- De Broglie gravity

We use an alternative interpretation of quantum mechanics, based on the Bohmian trajectory approach, and show that the quantum effects can be included in the classical equation of motion via a conformal transformation on the background metric. We apply this method to the Robertson-Walker metric to derive a modified version of Friedmann's equations for a Universe consisting of scalar, spin-zero, massive particles. These modified equations include additional terms that result from the non-local nature of matter and appear as an acceleration in the expansion of the Universe. We see that the same effect may also be present in the case of an inhomogeneous expansion.Comment: Accepted for publication in Ap

A filamentation instability for streaming cosmic-rays

We demonstrate that cosmic rays form filamentary structures in the precursors of supernova remnant shocks due to their self-generated magnetic fields. The cosmic-ray filamentation results in the growth of a long wavelength instability, and naturally couples the rapid non-linear amplification on small scales to larger length scales. Hybrid magnetohydrodynamics--particle simulations are performed to confirm the effect. The resulting large scale magnetic field may facilitate the scattering of high energy cosmic rays as required to accelerate protons beyond the knee in the cosmic-ray spectrum at supernova remnant shocks. Filamentation far upstream of the shock may also assist in the escape of cosmic rays from the accelerator.Comment: Accepted for publication in MNRA

On the Cosmic Ray Driven Firehose Instability

The role of the non-resonant firehose instability in conditions relevant to the precursors of supernova remnant shocks is considered. Using a second order tensor expansion of the Vlasov-Fokker-Planck equation we illustrate the necessary conditions for the firehose to operate. It is found that for very fast shocks, the diffusion approximation predicts that the linear firehose growth rate is marginally faster than its resonant counterpart. Preliminary hybrid MHD-Vlasov-Fokker-Planck simulation results using young supernova relevant parameters are presented.Comment: Contribution to the 6th International Symposium on High Energy Gamma-Ray Astronomy (Gamma2016), Heidelberg, Germany. To be published in the AIP Conference Proceeding

Inverse Compton emission from heavy WIMP annihilations in the Galactic Centre

A thermal relic WIMP remains a prime candidate for the nature of Dark Matter,particularly for the more poorly constrained case of a heavy ($\gtrsim$ 1 TeV)WIMP. The highest fluxes from WIMP annihilations are expected in the region ofthe Galactic Centre (GC) where current and near future gamma-ray observatoriescan be exploited to place tight limits on the WIMP paradigm. It is regularlynoted that the annihilation flux of gammas will be accompanied by chargedsecondary particles which can produce 'delayed' inverse Compton (IC) gamma-rayemission, but this component is often neglected in indirect Dark Mattersearches. In this work the inverse Compton emission is studied for the specificconditions of heavy WIMP annihilation in the GC. Using models for the magneticand radiation fields of the region, and taking into consideration the transportof secondary particles, we find that for TeV WIMPs the IC component cannot beneglected in the GC, with the particles produced cooling within the regionrather than propagating out in to the Galaxy. This effect changes the predictedspectral shape substantially and thus boosts the detection prospects for heavyWIMPs.<br

The transport of cosmic rays in self-excited magnetic turbulence

The process of diffusive shock acceleration relies on the efficacy with which hydromagnetic waves can scatter charged particles in the precursor of a shock. The growth of self-generated waves is driven by both resonant and non-resonant processes. We perform high-resolution magnetohydrodynamic simulations of the non-resonant cosmic-ray driven instability, in which the unstable waves are excited beyond the linear regime. In a snapshot of the resultant field, particle transport simulations are carried out. The use of a static snapshot of the field is reasonable given that the Larmor period for particles is typically very short relative to the instability growth time. The diffusion rate is found to be close to, or below, the Bohm limit for a range of energies. This provides the first explicit demonstration that self-excited turbulence reduces the diffusion coefficient and has important implications for cosmic ray transport and acceleration in supernova remnants.Comment: 8 pages, 8 figures, accepted for publication in MNRA

A cosmic ray current driven instability in partially ionised media

We investigate the growth of hydromagnetic waves driven by streaming cosmic rays in the precursor environment of a supernova remnant shock. It is known that transverse waves propagating parallel to the mean magnetic field are unstable to anisotropies in the cosmic ray distribution, and may provide a mechanism to substantially amplify the ambient magnetic field. We quantify the extent to which temperature and ionisation fractions modify this picture. Using a kinetic description of the plasma we derive the dispersion relation for a collisionless thermal plasma with a streaming cosmic ray current. Fluid equations are then used to discuss the effects of neutral-ion collisions. We calculate the extent to which the environment into which the cosmic rays propagate influences the growth of the magnetic field, and determines the range of possible growth rates. If the cosmic ray acceleration is efficient, we find that very large neutral fractions are required to stabilise the growth of the non-resonant mode. For typical supernova parameters in our galaxy, thermal effects do not significantly alter the growth rates. For weakly driven modes, ion-neutral damping can dominate over the instability at more modest ionisation fractions. In the case of a supernova shock interacting with a molecular clouds, such as in RX J1713.7-3946, with high density and low ionisation, the modes can be rapidly damped.Comment: 5 pages, 2 figures, accepted to A&A. Corrections made. Applications adde

Environmental limits on the non-resonant cosmic-ray current-driven instability

We investigate the so-called non-resonant cosmic-ray streaming instability, first discussed by Bell (2004). The extent to which thermal damping and ion-neutral collisions reduce the growth of this instability is calculated. Limits on the growth of the non-resonant mode in SN1006 and RX J1713.7-3946 are presented.Comment: 4 pages, 1 figure, contributed talk at the workshop: High Energy Phenomena in Relativistic Outflows (HEPRO), Dublin, 24-28 September 200

Education and referral criteria: impact on oncology referrals to palliative care.

OBJECTIVE: To describe a quality improvement project involving education and referral criteria to influence oncology provider referrals to a palliative care service. METHODS: A single group post-test only quasi-experimental design was used to evaluate palliative care service (PCS) referrals following an intervention consisting of a didactic presentation, education outreach visits (EOV) to key providers, and referral criteria. Data on patient demographics, cancer types, consult volume, reasons for referral, pre-consult length of stay, overall hospital stay, and discharge disposition were collected pre-intervention, then post-intervention for 7.5 months and compared. SETTING AND SAMPLE: Attending oncologists, nurse practitioner, and house staff from the solid tumor division at a 700-bed urban teaching hospital participated in the project. Two geriatricians, a palliative care nurse practitioner, and rotating geriatric fellows staffed the PCS. RESULTS: The percentage of oncology referrals to PCS increased significantly following the intervention (χ(2) = 6.108, p = .013). 24.9% (390) patients were referred in the 4.6 years pre-intervention and 31.5% (106) patients were referred during 7.5 months post-intervention. The proportion of consults for pain management was significantly greater post-intervention (χ(2) = 5.378, p = .02), compared to pre-intervention, when most referrals were related to end-of-life issues. Lung, pancreatic, and colon were the most common cancer types at both periods, and there were no significant differences in patient demographics, pre-referral length of hospitalization or overall hospital days. There was a trend toward more patients being discharged alive following the intervention. CONCLUSION: A quality improvement project supported the use of education and referral criteria to influence both the frequency and reasons for palliative care referral by oncology providers