Interacting dark matter contribution to the Galactic 511 keV gamma ray emission: constraining the morphology with INTEGRAL/SPI observations

We compare the full-sky morphology of the 511 keV gamma ray excess measured by the INTEGRAL/SPI experiment to predictions of models based on dark matter (DM) scatterings that produce low-energy positrons: either MeV-scale DM that annihilates directly into e+e- pairs, or heavy DM that inelastically scatters into an excited state (XDM) followed by decay into e+e- and the ground state.By direct comparison to the data, we find that such explanations are consistent with dark matter halo profiles predicted by numerical many-body simulations for a Milky Way-like galaxy. Our results favor an Einasto profile over the cuspier NFW distribution and exclude decaying dark matter scenarios whose predicted spatial distribution is too broad. We obtain a good fit to the shape of the signal using six fewer degrees of freedom than previous empirical fits to the 511 keV data. We find that the ratio of flux at Earth from the galactic bulge to that of the disk is between 1.9 and 2.4, taking into account that 73% of the disk contribution may be attributed to the beta decay of radioactive 26Al.Comment: 7 pages, 4 figures. Includes minor corrections, and a discussion of threshold energies in XDM models. Published in JCA

The effect of underwater sounds on shark behaviour

The effect of sound on the behaviour of sharks has not been investigated since the 1970s. Sound is, however, an important sensory stimulus underwater, as it can spread in all directions quickly and propagate further than any other sensory cue. We used a baited underwater camera rig to record the behavioural responses of eight species of sharks (seven reef and coastal shark species and the white shark, Carcharodon carcharias) to the playback of two distinct sound stimuli in the wild: an orca call sequence and an artificially generated sound. When sounds were playing, reef and coastal sharks were less numerous in the area, were responsible for fewer interactions with the baited test rigs, and displayed less ‘inquisitive’ behaviour, compared to during silent control trials. White sharks spent less time around the baited camera rig when the artificial sound was presented, but showed no significant difference in behaviour in response to orca calls. The use of the presented acoustic stimuli alone is not an effective deterrent for C. carcharias. The behavioural response of reef sharks to sound raises concern about the effects of anthropogenic noise on these taxa

Complex Kerr Geometry and Nonstationary Kerr Solutions

In the frame of the Kerr-Schild approach, we consider the complex structure of Kerr geometry which is determined by a complex world line of a complex source. The real Kerr geometry is represented as a real slice of this complex structure. The Kerr geometry is generalized to the nonstationary case when the current geometry is determined by a retarded time and is defined by a retarded-time construction via a given complex world line of source. A general exact solution corresponding to arbitrary motion of a spinning source is obtained. The acceleration of the source is accompanied by a lightlike radiation along the principal null congruence. It generalizes to the rotating case the known Kinnersley class of "photon rocket" solutions.Comment: v.3, revtex, 16 pages, one eps-figure, final version (to appear in PRD), added the relation to twistors and algorithm of numerical computations, English is correcte

High spectral resolution Fabry-Perot interferometer measurements of comet Halley at H-alpha and 6300 A

A 40.6 cm Newtonian telescope has been interfaced to the Fabry-Perot interferometer at the Arecibo Observatory to make high spectral resolution measurements of Comet Halley emissions at 6562.72 A (H-alpha) and 6300.3 A (OI). In March 1986 the H-alpha surface brightness for a 5'.9 field of view centered on the comet nucleus decreased from 39+/-7.8 rayleighs on 12 March to 16+/-3.8 rayleighs on 23 March. The atomic hydrogen production rate on 12 March 1986 was 1.62+/-0.5 x 1030 s-1, and on 23 March 1986 it was 6.76+/-2.3 x 1029 s-1. Using spectral resolution of 0.196 A, we found the atomic hydrogen outflow velocity to be approximately 7.9+/-1.0 km s-1. In general, the H-alpha spectra are highly structured, and indicative of a multiple component atomic hydrogen velocity distribution. An isotropic outflow of atomic hydrogen at various velocities is not adequate to explain the spectra measured at H-alpha. The 6300.3 A emission of O(1D) had a surface brightness of 81+/-16 rayleighs on 15 March 1986, and 95+/-11 rayleighs on 17 March 1986. After adjustment for atmospheric extinction, the implied O(1D) production rate on 15 March is 6.44+/-3.0 x 1028 s-1, and the production rate on 17 March is 5.66+/-2.7 x 1028 s-1. These spectra included a feature at 6300.8 A that we attribute to NH2. The brightness of this emission feature was 37+/-11 rayleighs on 15 March.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25881/1/0000444.pd

Adjustment to colostomy: stoma acceptance, stoma care self-efficacy and interpersonal relationships

‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing. DOI: 10.1111/j.1365-2648.2007.04446.xThis paper is a report of a study to examine adjustment and its relationship with stoma acceptance and social interaction, and the link between stoma care self-efficacy and adjustment in the presence of acceptance and social interactions.Peer reviewe

Dynamic mechanical thermal analysis of aqueous sugar solutions containing fructose, glucose, sucrose, maltose and lactose

The glass transition of glucose, fructose, lactose, maltose and sucrose solutions at maximum cryo-concentration was studied by Dynamic Mechanical Thermal Analysis (DMTA), using the disc bending technique. The glass transition temperatures were determined from the peaks in the loss modulus E′′, which corresponds theoretically to the resonance point (Maxwell model) for several input frequencies. The frequency dependence was well described by both an Arrhenius-type model and by the WLF (Williams, Landel and Ferry) equation, yielding glass transition temperatures for an average molecular vibration time of 100 s, which were similar to published midpoint temperatures determined by DSC scans. Some sugar mixtures were studied, yielding results that were well described by the Gordon–Taylor equation, using literature data. The frequency dependence of the viscoelastic ratio was also well approximated by an Arrhenius-type equation, with activation energies similar to those of the glass transition temperature and corresponded well to published values of the endset of glass transition

A jump-growth model for predator-prey dynamics: derivation and application to marine ecosystems

This paper investigates the dynamics of biomass in a marine ecosystem. A stochastic process is defined in which organisms undergo jumps in body size as they catch and eat smaller organisms. Using a systematic expansion of the master equation, we derive a deterministic equation for the macroscopic dynamics, which we call the deterministic jump-growth equation, and a linear Fokker-Planck equation for the stochastic fluctuations. The McKendrick--von Foerster equation, used in previous studies, is shown to be a first-order approximation, appropriate in equilibrium systems where predators are much larger than their prey. The model has a power-law steady state consistent with the approximate constancy of mass density in logarithmic intervals of body mass often observed in marine ecosystems. The behaviours of the stochastic process, the deterministic jump-growth equation and the McKendrick--von Foerster equation are compared using numerical methods. The numerical analysis shows two classes of attractors: steady states and travelling waves.Comment: 27 pages, 4 figures. Final version as published. Only minor change

Structure of Complement Component C2a: Implications for Convertase Formation and Substrate Binding

SummaryC2a provides the catalytic center to the convertase complexes of the classical and lectin-binding pathways of complement activation. We determined two crystal structures of full-length C2a, with and without a pseudo ligand bound. Both structures reveal a near-active conformation of the catalytic center of the serine protease domains, while the von Willebrand factor A-type domains display an intermediate activation state of helix α7 with an open, activated metal-ion-dependent adhesion site. The open adhesion site likely serves to enhance the affinity for the ligand C4b, similar to “inside-out” signaling in integrins. Surprisingly, the N-terminal residues of C2a are buried in a crevice near helix α7, indicative of a structural switch between C2 and C2a. Extended loops on the protease domain possibly envelop the protruding anaphylatoxin domain of the substrate C3. Together with a putative substrate-induced completion of the oxyanion hole, this may contribute to the high substrate specificity of the convertases

Rapid entry and downregulation of T Cells in the central nervous system During the reinduction of experimental autoimmune encephalomyelitis

We investigated the mechanisms whereby a previous attack of experimental autoimmune encephalomyelitis (EAE) modifies a subsequent attack in the Lewis rat. Active immunization with myelin basic protein (MBP) and complete Freund's adjuvant 28 days after the passive transfer of MBP-sensitized spleen cells induced a second episode of EAE, which occurred earlier than in naive control animals, but was less severe overall. The pattern of neurological signs was also different in rechallenged rats, which had less severe tail and hindlimb weakness but more severe forelimb weakness. In rechallenged rats, inflammation was more severe in the cervical spinal cord, cerebellum, brainstem and cerebrum, but less severe in the lumbar spinal cord, than in controls. The early onset of EAE in rechallenged rats was explained by a memory T cell response to MBP72-89 in the draining lymph node and spleen, and by the enhanced entry of T cells into the central nervous system (CNS). However, the number of alpha beta T cells in the spinal cord of rechallenged rats declined faster than in controls, especially in the lumbosacral cord, where the number of V beta 8.2+ T cells and the frequency of T cells reactive to MBP72-89 rapidly decreased, indicating rapid downregulation of the immune response in the previously inflamed spinal cord. Apoptosis of inflammatory cells in the CNS was increased in the rechallenged rats and is likely to contribute to this downregulation. Furthermore, during the disease course the generation of encephalitogenic T cells in the peripheral lymphoid organs was limited compared with controls. Thus, a previous attack of EAE modifies a subsequent attack through the interaction of the following processes: a memory T cell response to MBP; facilitated T cell entry into the CNS; downregulation of the immune response in the CNS, including increased apoptosis of inflammatory cells; and a limited generation of encephalitogenic T cells in the peripheral lymphoid organs

Tree method for quantum vortex dynamics

We present a numerical method to compute the evolution of vortex filaments in superfluid helium. The method is based on a tree algorithm which considerably speeds up the calculation of Biot-Savart integrals. We show that the computational cost scales as Nlog{(N) rather than N squared, where $N$ is the number of discretization points. We test the method and its properties for a variety of vortex configurations, ranging from simple vortex rings to a counterflow vortex tangle, and compare results against the Local Induction Approximation and the exact Biot-Savart law.Comment: 12 pages, 10 figure