High energy neutral emissions from solar flares

Solar flares produce two kinds of high-energy neutral emissions: gamma-rays and neutrons (with thanks to Chupp 1984, for this convenient title). These originate in interactions between accelerated ions and ambient nuclei and, between the photons and the neutrons, provide a window into the fast ion population between the energies of a few MeV and a few hundred MeV. Previously, the gamma-ray spectrum has been investigated by Monte Carlo modelling methods and conditions in the flare region deduced by adjusting the models to fit the observed spectra, chiefly from the Solar Maximum Mission Gamma Ray Spectrometer (e.g. Murphy et al. 1991). This provides abundances for accelerated ions and ambient nuclei, and energy distributions for the accelerated ions. However a number of assumptions have to be made in order to keep the model parameter numbers low enough to enable statistical matching to the data in a reasonable amount of processor time and there are some difficulties with the parameters deduced. In particular, there are difficulties in accounting for the brightness of the narrow emission line at 1.63 MeV due to the deexcitation of 20Ne. This demands a steep accelerated ion spectrum and a low abundance for fast alpha-particles. However, strong emission in the 0.429 MeV and 0.478 MeV features due to the production of lithium and beryllium by fusion of alpha-particles often contradicts this, demanding an enhanced population of accelerated alpha-particles. Fresh approaches to the modelling of some of the narrow lines are presented here in order to explore, and possibly resolve, this contradiction. Two possibilities are examined; the assumptions in previous work of a cold target region and the further assumption that all of the accelerated ions share the same energy distribution. It may be that the accelerated ions pass through a region in which, at least for the lower energy ions, energy loss is experienced in warm target conditions (e.g. Emslie et al. 1997). If they spend a sufficient part of their time in such a region, their energy distribution will be altered to enhance the number of ions at energies of a few MeV. This would preferentially stimulate the 1.63 MeV line due to the particularly low energy sensitivity of 20Ne to proton-excitation, without having to invoke a steep ion spectrum. Previous attempts to apply this analysis did not model the line production in detail and considered only the peak values of the excitation cross-sections. Integrating the excitation in detail allows a resonant spike at 3 MeV in the 20Ne cross-section to have its effect and reduce the required proton energy slope. Even with a large proportion of accelerated alpha-particles, this approach can reduce the ion slope and significantly reduce the required ion energy in the flare. The second assumption challenged here, is that all of the accelerated ions have the same energy distribution, characterized by a single power-law index. Relaxing this assumption and modelling the lines with separate fast proton and fast alpha-particle power-laws has significant results. It is possible to satisfy the bright 1.63 MeV line and the strong emission from the alpha-fusion reactions with a steep proton spectrum and a hard alpha-particle spectrum. This also significantly reduces the required alpha-particle abundance to values more in line with cosmic abundances. Rounding out this work on high-energy neutral emissions, the GUIPS software has been applied to correctly inverting a Compton Gamma Ray Observatory COMPTEL neutron spectrum from the solar flare of 15 June 1991. Maximum entropy and quadratic inversion techniques are applied to the instrument data to produce an improved neutron spectrum. Previous simplified approaches have underestimated the sensitivity of the instrument as well as distorting the neutron spectrum. A dip in the spectrum has been confirmed but the overall number of neutrons detected has to be reduced to 73% of the previous value obtained by Kocharov et al. (1998). Further investigation of COMPTEL neutron spectra awaits the preparation of the data. This depends on extensive work modelling the passage of the solar neutrons through the instrument using the Los Alamos LAHET and MCNP software

Very High Energy Observations of Gamma-Ray Burst Locations with the Whipple Telescope

Gamma-ray burst (GRB) observations at very high energies (VHE, E > 100 GeV) can impose tight constraints on some GRB emission models. Many GRB afterglow models predict a VHE component similar to that seen in blazars and plerions, in which the GRB spectral energy distribution has a double-peaked shape extending into the VHE regime. VHE emission coincident with delayed X-ray flare emission has also been predicted. GRB follow-up observations have had high priority in the observing program at the Whipple 10m Gamma-ray Telescope and GRBs will continue to be high priority targets as the next generation observatory, VERITAS, comes on-line. Upper limits on the VHE emission, at late times (>~4 hours), from seven GRBs observed with the Whipple Telescope are reported here.Comment: Accepted for publication in the January 20, 2007 volume of the Astrophysical Journal, 655, 39

Deliver us from Evil: The Effects of Mortality Salience and Reminders of 9/11 on Support for President George W. Bush

According to terror management theory, heightened concerns about mortality should intensify the appeal of charismatic leaders. To assess this idea, we investigated how thoughts about death and the 9/11 terrorist attacks influence Americans’ attitudes toward current U.S. President George W. Bush. Study 1 found that reminding people of their own mortality (mortality salience) increased support for Bush and his counterterrorism policies. Study 2 demonstrated that subliminal exposure to 9/11-related stimuli brought death-related thoughts closer to consciousness. Study 3 showed that reminders of both mortality and 9/11 increased support for Bush. In Study 4, mortality salience led participants to become more favorable toward Bush and voting for him in the upcoming election but less favorable toward Presidential candidate John Kerry and voting for him. Discussion focused on the role of terror management processes in allegiance to charismatic leaders and political decision making.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Accelerated BEP for metastatic germ cell tumours: a multicenter phase II trial by the Australian and New Zealand Urogenital and Prostate Cancer Trials Group (ANZUP)

Background This Australian single-arm, multicenter, phase II trial evaluated feasibility, tolerability and activity of accelerated bleomycin, etoposide and cisplatin (BEP) as first-line chemotherapy for metastatic germ cell tumours.Patients and methods Patients were planned to receive cisplatin 20 mg/m2 and etoposide 100 mg/m2 days 1–5, and pegfilgrastim 6 mg day 6, all repeated every 2 weeks for four cycles (three cycles for good prognosis). Bleomycin was given at 30 000 IU weekly to a total of 12 doses (9 doses for good prognosis). Primary end point was feasibility, defined as the proportion of patients able to complete the etoposide and cisplatin components of BEP and be eligible to receive a fourth cycle of BEP by day 50.Results Twelve poor, 16 intermediate and 15 good prognosis (n = 43) eligible patients were enrolled. Two patients aged >40 years were ineligible and excluded from analyses. The regimen was feasible in 86%, not feasible in 7% and not assessable in 7% of patients. Most common grade 3/4 adverse events were non-neutropenic infection (16%) and febrile neutropenia (12%). Complete response (CR) to chemotherapy and surgery was achieved in 33% poor-prognosis, 81% intermediate-prognosis and 100% good-prognosis patients. At median follow-up of 27 months (range 6–42), the 2-year progression-free survival was 50% for poor-prognosis, 94% for intermediate-prognosis and 92% for good-prognosis patients.Conclusion Accelerated BEP is feasible and tolerable. Efficacy data appear to be promising. This trial and a similar UK study provide the rationale for a randomised trial comparing accelerated versus standard BEP. Australian New Zealand Clinical Trials Registry Registration number. ACTRN 12607000294459