Dark matter annihilation at the galactic center

If cold dark matter is present at the galactic center, as in current models of the dark halo, it is accreted by the central black hole into a dense spike. Particle dark matter then annihilates strongly inside the spike, making it a compact source of photons, electrons, positrons, protons, antiprotons, and neutrinos. The spike luminosity depends on the density profile of the inner halo: halos with finite cores have unnoticeable spikes, while halos with inner cusps may have spikes so bright that the absence of a detected neutrino signal from the galactic center already places interesting upper limits on the density slope of the inner halo. Future neutrino telescopes observing the galactic center could probe the inner structure of the dark halo, or indirectly find the nature of dark matter.Comment: 4 pages, 5 figure

New Gamma-Ray Contributions to Supersymmetric Dark Matter Annihilation

We compute the electromagnetic radiative corrections to all leading annihilation processes which may occur in the Galactic dark matter halo, for dark matter in the framework of supersymmetric extensions of the Standard Model (MSSM and mSUGRA), and present the results of scans over the parameter space that is consistent with present observational bounds on the dark matter density of the Universe. Although these processes have previously been considered in some special cases by various authors, our new general analysis shows novel interesting results with large corrections that may be of importance, e.g., for searches at the soon to be launched GLAST gamma-ray space telescope. In particular, it is pointed out that regions of parameter space where there is a near degeneracy between the dark matter neutralino and the tau sleptons, radiative corrections may boost the gamma-ray yield by up to three or four orders of magnitude, even for neutralino masses considerably below the TeV scale, and will enhance the very characteristic signature of dark matter annihilations, namely a sharp step at the mass of the dark matter particle. Since this is a particularly interesting region for more constrained mSUGRA models of supersymmetry, we use an extensive scan over this parameter space to verify the significance of our findings. We also re-visit the direct annihilation of neutralinos into photons and point out that, for a considerable part of the parameter space, internal bremsstrahlung is more important for indirect dark matter searches than line signals.Comment: Replaced Fig. 2c which by mistake displayed the same spectrum as Fig. 2d; the radiative corrections reported here are now implemented in DarkSUSY which is available at http://www.physto.se/~edsjo/darksusy

Human resources for control of tuberculosis and HIV-associated tuberculosis.

The global targets for tuberculosis (TB) control were postponed from 2000 to 2005, but on current evidence a further postponement may be necessary. Of the constraints preventing these targets being met, the primary one appears to be the lack of adequately trained and qualified staff. This paper outlines: 1) the human resources and skills for global TB and human immunodeficiency virus (HIV) TB control, including the human resources for implementing the DOTS strategy, the additional human resources for implementing joint HIV-TB control strategies and what is known about human resource gaps at global level; 2) the attempts to quantify human resource gaps by focusing on a small country in sub-Saharan Africa, Malawi; and 3) the main constraints to human resources and their possible solutions, under six main headings: human resource planning; production of human resources; distribution of the work-force; motivation and staff retention; quality of existing staff; and the effect of HIV/AIDS. We recommend an urgent shift in thinking about the human resource paradigm, and exhort international policy makers and the donor community to make a concerted effort to bridge the current gaps by investing for real change

Two photon annihilation of Kaluza-Klein dark matter

We investigate the fermionic one-loop cross section for the two photon annihilation of Kaluza-Klein (KK) dark matter particles in a model of universal extra dimensions (UED). This process gives a nearly mono-energetic gamma-ray line with energy equal to the KK dark matter particle mass. We find that the cross section is large enough that if a continuum signature is detected, the energy distribution of gamma-rays should end at the particle mass with a peak that is visible for an energy resolution of the detector at the percent level. This would give an unmistakable signature of a dark matter origin of the gamma-rays, and a unique determination of the dark matter particle mass, which in the case studied should be around 800 GeV. Unlike the situation for supersymmetric models where the two-gamma peak may or may not be visible depending on parameters, this feature seems to be quite robust in UED models, and should be similar in other models where annihilation into fermions is not helicity suppressed. The observability of the signal still depends on largely unknown astrophysical parameters related to the structure of the dark matter halo. If the dark matter near the galactic center is adiabatically contracted by the central star cluster, or if the dark matter halo has substructure surviving tidal effects, prospects for detection look promising.Comment: 17 pages, 3 figures; slightly revised versio

Hemodialysis-associated protein catabolism with and without glucose in the dialysis fluid

Hemodialysis-associated protein catabolism with and without glucose in the dialysis fluid. The effects of hemodialysis on protein and energy metabolism were studied in eight hemodialysis patients. The leg exchange of amino acids (AA) was measured during hemodialysis using a dialysis fluid with 10 mmol/liter glucose (GD) or without glucose (GFD). Arterial AA concentrations decreased by about 30% in GD and GFD. During dialysis, similar increases in the efflux of AA from leg tissues (mainly muscle) were observed in GD and GFD (basal 105 ± 104, vs. 71 ± 62 nmol/min/100 g tissue; dialysis 295 ± 46 vs. 289 ± 60 nmol/min/100 g tissue). The efflux of AA remained largely unchanged at one hour after the end of GD and GFD. Losses of AA to the dialysate were similar during GD (8.3 ± 0.9 g) and GFD (7.9 ± 0.4; NS). GFD resulted in a loss of 26 g of glucose whereas 30 of glucose was absorbed during GD. The amount of urea removed by dialysis and the post-dialysis increase in plasma urea were similar in GD and GFD. In conclusion, the addition of glucose to the dialysis fluid may help the energy balance, but it does not appear to reduce the negative effects of hemodialysis on protein metabolism

Diffuse inverse Compton and synchrotron emission from dark matter annihilations in galactic satellites

Annihilating dark matter particles produce roughly as much power in electrons and positrons as in gamma ray photons. The charged particles lose essentially all of their energy to inverse Compton and synchrotron processes in the galactic environment. We discuss the diffuse signature of dark matter annihilations in satellites of the Milky Way (which may be optically dark with few or no stars), providing a tail of emission trailing the satellite in its orbit. Inverse Compton processes provide X-rays and gamma rays, and synchrotron emission at radio wavelengths might be seen. We discuss the possibility of detecting these signals with current and future observations, in particular EGRET and GLAST for the gamma rays.Comment: 13 pages, 5 figure

Antimatter spectra from a time-dependent modeling of supernova remnants

We calculate the energy spectra of cosmic rays (CR) and their secondaries produced in a supernova remnant (SNR), taking into account the time-dependence of the SNR shock. We model the trajectories of charged particles as a random walk with a prescribed diffusioncoefficient, accelerating the particles at each shock crossing. Secondary production by CRs colliding with gas is included as a Monte Carlo process. We find that SNRs produce less antimatter than suggested previously: The positron/electron ratio and the antiproton/proton ratio are a few percent and few $\times 10^{-5}$, respectively. Both ratios do not rise with energy.Comment: 4 pages, 4 eps figures; v2: results for time-dependent magnetic field adde

Indirect signals from light neutralinos in supersymmetric models without gaugino mass unification

We examine indirect signals produced by neutralino self-annihilations, in the galactic halo or inside celestial bodies, in the frame of an effective MSSM model without gaugino-mass unification at a grand unification scale. We compare our theoretical predictions with current experimental data of gamma-rays and antiprotons in space and of upgoing muons at neutrino telescopes. Results are presented for a wide range of the neutralino mass, though our discussions are focused on light neutralinos. We find that only the antiproton signal is potentially able to set constraints on very low-mass neutralinos, below 20 GeV. The gamma-ray signal, both from the galactic center and from high galactic latitudes, requires significantly steep profiles or substantial clumpiness in order to reach detectable levels. The up-going muon signal is largely below experimental sensitivities for the neutrino flux coming from the Sun; for the flux from the Earth an improvement of about one order of magnitude in experimental sensitivities (with a low energy threshold) can make accessible neutralino masses close to O, Si and Mg nuclei masses, for which resonant capture is operative.Comment: 17 pages, 1 tables and 5 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/indirect04.ps.gz or through http://www.astroparticle.to.infn.it/. Limit from BR(Bs--> mu+ mu-) adde