Gamma-ray signatures of annihilation to charged leptons in dark matter substructure

Due to their higher concentrations and small internal velocities, Milky Way subhalos can be at least as important as the smooth halo in accounting for the GeV positron excess via dark matter annihilation. After showing how this can be achieved in various scenarios, including in Sommerfeld models, we demonstrate that, in this case, the diffuse inverse-Compton emission resulting from electrons and positrons produced in substructure leads to a nearly-isotropic signal close to the level of the isotropic GeV gamma-ray background seen by Fermi. Moreover, we show that HESS cosmic-ray electron measurements can be used to constrain multi-TeV internal bremsstrahlung gamma rays arising from annihilation to charged leptons.Comment: 8 pages, 4 figures; minor updates to match published versio

Apoptotic depletion of CD4<SUP>+</SUP> T cells in idiopathic CD4<SUP>+</SUP> T lymphocytopenia

Progressive loss of CD4+ T lymphocytes, accompanied by opportunistic infections characteristic of the acquired immune deficiency syndrome, ahs been reported in the absence of any known etiology. The pathogenesis of this syndrome, a subset of idiopathic CD4+ T lymphocytopenia (ICL), is uncertain. We report that CD4+ T cells from seven of eight ICL patients underwent accelerated programmed cell death, a process facilitated by T cell receptor cross-linking. Apoptosis was associated with enhanced expression of Fas and Fas ligand in unstimulated cell populations, and partially inhibited by soluble anti-Fas mAb. In addition, apoptosis was suppressed by aurintricarboxylic acid, an inhibitor of calcium-dependent endonucleases and proteases, in cells from four of seven patients, The in vivo significance of these findings was supported by three factors: the absence of accelerated apoptosis in persons with stable, physiologic CD4 lymphopenia without clinical immune deficiency; detection of serum antihistone H2B autoantibodies, one consequence of DNA fragmentation, in some patients; and its selectivity, with apoptosis limited to the CD4 population in some, and occurring among CD8+ T cells predominantly in those individuals with marked depletion of both CD4+ T lymphocytes linked to clinical immune suppression have evidence for accelerated T cell apoptosis in vitro that may be pathophysiologic and amenable to therapy with apoptosis inhibitors

A luminosity constraint on the origin of unidentified high energy sources

The identification of point sources poses a great challenge for the high energy community. We present a new approach to evaluate the likelihood of a set of sources being a Galactic population based on the simple assumption that galaxies similar to the Milky Way host comparable populations of gamma-ray emitters. We propose a luminosity constraint on Galactic source populations which complements existing approaches by constraining the abundance and spatial distribution of any objects of Galactic origin, rather than focusing on the properties of a specific candidate emitter. We use M31 as a proxy for the Milky Way, and demonstrate this technique by applying it to the unidentified EGRET sources. We find that it is highly improbable that the majority of the unidentified EGRET sources are members of a Galactic halo population (e.g., dark matter subhalos), but that current observations do not provide any constraints on all of these sources being Galactic objects if they reside entirely in the disk and bulge. Applying this method to upcoming observations by the Fermi Gamma-ray Space Telescope has the potential to exclude association of an even larger number of unidentified sources with any Galactic source class.Comment: 18 pages, 4 figures, to appear in JPhys

Constraints on dark matter models from a Fermi LAT search for high-energy cosmic-ray electrons from the Sun

During its first year of data taking, the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope has collected a large sample of high-energy cosmic-ray electrons and positrons (CREs). We present the results of a directional analysis of the CRE events, in which we searched for a flux excess correlated with the direction of the Sun. Two different and complementary analysis approaches were implemented, and neither yielded evidence of a significant CRE flux excess from the Sun. We derive upper limits on the CRE flux from the Sun's direction, and use these bounds to constrain two classes of dark matter models which predict a solar CRE flux: (1) models in which dark matter annihilates to CREs via a light intermediate state, and (2) inelastic dark matter models in which dark matter annihilates to CREs.Comment: 18 pages, 8 figures, accepted for publication in Physical Review D - contact authors: Francesco Loparco ([email protected]), M. Nicola Mazziotta ([email protected]) and Jennifer Siegal-Gaskins ([email protected]

Increased expression of TLR7 and TLR9 in alopecia areata

YesAlopecia areata (AA) is thought to be an autoimmune process. In other autoimmune diseases, the innate immune system and Toll‐like receptors (TLRs) can play a significant role. Expression of TLR7, TLR9 and associated inducible genes was evaluated by quantitative PCR in peripheral blood mononuclear cells (PBMCs) from 10 healthy individuals and 19 AA patients, categorized according to disease duration, activity and hair loss extent. Microdissected scalp biopsies from five patients and four controls were also assessed by quantitative PCR and immunohistology. TLR9 was significantly upregulated 2.37 fold in AA PBMCs. Notably, TLR9 was most significantly upregulated in patients with active AA, as shown by a positive hair pull test, compared to stable AA patients. In hair follicle bulbs from AA patients, IFNG and TLR7 exhibited statistically significant 3.85 and 2.70 fold increases in mRNA, respectively. Immunohistology revealed TLR7 present in lesional follicles, while TLR9 positive cells were primarily observed peri‐bulbar to AA affected hair follicles. The increased expression of TLR7 and TLR9 suggest components of the innate immune system may be active in AA pathogenesis.National Alopecia Areata Foundation; Canadian Dermatology Foundation; Michael Smith Foundation for Health Research, Grant/Award Number: CI‐SCH‐00480(06‐1); Canadian Institutes of Health Research, Grant/Award Number: MOP‐167368 and MSH‐192593‐14045

Exploring children’s perspectives on the welfare needs of pet animals

This work was supported by the Department for Environment, Food and Rural Affairs (grant number AW1404).Children are increasingly viewed as important recipients of eduational interventions to improve animal welfare, yet research examining their perspectives is lacking, particularly within the UK. Helping children to care appropriately for animals depends, not least, on an ability to understand the needs of different species and correctly identify cues given by the animal that indicate its welfare state. This study began to explore: (a) children’s perceptions of welfare needs, focusing on four common pet animals; (b) influences on the development of knowledge; (c) beliefs about whether or not (all) animals are sentient, and (d) their confidence in identifying when their own pets are in need. Fourteen focus groups were carried out with 53 children aged 7 to 13 years. Findings highlighted an affirmative response that animals have feelings (dogs especially), albeit with doubts about this applying universally. There was wide variation in children’s knowledge of welfare needs, even among owners of the animal in question. Conversely, some children lacked confidence in spite of the extensive knowledge they had developed through direct experience. An important finding was a perceived difficulty in identifying the needs of particular species or specific types of need in their own pets. Fitting well with a recent emphasis on “positive welfare,” children felt that many animals need demonstrative love and attention, especially cats and dogs. While there is clearly scope for educating children about common needs and cues that indicate animals’ welfare state, other areas pose a greater challenge. Emotional connection seems important in the development of extensive knowledge and concern for welfare. Accordingly, animals that do not possess the kind of behavioral repertoire that is easy to interpret or allows for a perceived sense of reciprocity are possibly at risk of negative welfare experiences.PostprintPeer reviewe

Evolution of Robustness to Noise and Mutation in Gene Expression Dynamics

Phenotype of biological systems needs to be robust against mutation in order to sustain themselves between generations. On the other hand, phenotype of an individual also needs to be robust against fluctuations of both internal and external origins that are encountered during growth and development. Is there a relationship between these two types of robustness, one during a single generation and the other during evolution? Could stochasticity in gene expression have any relevance to the evolution of these robustness? Robustness can be defined by the sharpness of the distribution of phenotype; the variance of phenotype distribution due to genetic variation gives a measure of `genetic robustness' while that of isogenic individuals gives a measure of `developmental robustness'. Through simulations of a simple stochastic gene expression network that undergoes mutation and selection, we show that in order for the network to acquire both types of robustness, the phenotypic variance induced by mutations must be smaller than that observed in an isogenic population. As the latter originates from noise in gene expression, this signifies that the genetic robustness evolves only when the noise strength in gene expression is larger than some threshold. In such a case, the two variances decrease throughout the evolutionary time course, indicating increase in robustness. The results reveal how noise that cells encounter during growth and development shapes networks' robustness to stochasticity in gene expression, which in turn shapes networks' robustness to mutation. The condition for evolution of robustness as well as relationship between genetic and developmental robustness is derived through the variance of phenotypic fluctuations, which are measurable experimentally.Comment: 25 page

Searches for Cosmic-Ray Electron Anisotropies with the Fermi Large Area Telescope

The Large Area Telescope on board the \textit{Fermi} satellite (\textit{Fermi}-LAT) detected more than 1.6 million cosmic-ray electrons/positrons with energies above 60 GeV during its first year of operation. The arrival directions of these events were searched for anisotropies of angular scale extending from $\sim$ 10 $^\circ$ up to 90$^\circ$, and of minimum energy extending from 60 GeV up to 480 GeV. Two independent techniques were used to search for anisotropies, both resulting in null results. Upper limits on the degree of the anisotropy were set that depended on the analyzed energy range and on the anisotropy's angular scale. The upper limits for a dipole anisotropy ranged from $\sim0.5$ to $\sim10$.Comment: 16 pages, 10 figures, accepted for publication in Physical Review D - contact authors: M.N. Mazziotta and V. Vasileio

Dark Matter Annihilation around Intermediate Mass Black Holes: an update

The formation and evolution of Black Holes inevitably affects the distribution of dark and baryonic matter in the neighborhood of the Black Hole. These effects may be particularly relevant around Supermassive and Intermediate Mass Black Holes (IMBHs), the formation of which can lead to large Dark Matter overdensities, called {\em spikes} and {\em mini-spikes} respectively. Despite being larger and more dense, spikes evolve at the very centers of galactic halos, in regions where numerous dynamical effects tend to destroy them. Mini-spikes may be more likely to survive, and they have been proposed as worthwhile targets for indirect Dark Matter searches. We review here the formation scenarios and the prospects for detection of mini-spikes, and we present new estimates for the abundances of mini-spikes to illustrate the sensitivity of such predictions to cosmological parameters and uncertainties regarding the astrophysics of Black Hole formation at high redshift. We also connect the IMBHs scenario to the recent measurements of cosmic-ray electron and positron spectra by the PAMELA, ATIC, H.E.S.S., and Fermi collaborations.Comment: 12 pages, 7 figures. Invited contribution to NJP Focus Issue on "Dark Matter and Particle Physics