6,994 research outputs found

    Contributions to the width difference in the neutral DD system from hadronic decays

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    Recent studies of several multi-body D0D^0 meson decays have revealed that the final states are dominantly CPCP-even. However, the small value of the width difference between the two physical eigenstates of the D0D^0-D0\overline{D}{}^0 system indicates that the total widths of decays to CPCP-even and CPCP-odd final states should be the same to within about a percent. The known contributions to the width difference from hadronic D0D^0 decays are discussed, and it is shown that an apparent excess of quasi-CPCP-even modes is balanced, within current uncertainty, by interference effects in quasi-flavour-specific decays. Decay modes which may significantly affect the picture with improved measurements are considered.Comment: 17 pages including 3 tables. v2: Updated with published version including new comments in summar

    BBC3 (PUMA) regulates developmental apoptosis but not axonal injury induced death in the retina

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    <p>Abstract</p> <p>Background</p> <p>Naturally occurring apoptosis is a developmental process that shapes the retina by eliminating overproduced neurons. In the absence of the proapoptotic Bcl-2 family member BAX, developmental apoptosis in the retina is disrupted and extra neurons survive. It is unknown how BAX is activated or if this regulation varies between neuronal types and subtypes. Since the Bcl-2 family members BIM, BID, and BBC3 (PUMA) are powerful direct activators of BAX, we used mice deficient for each of these genes to investigate their importance in developmental apoptosis.</p> <p>Results</p> <p><it>Bax </it>deficient mice have an increase in retinal ganglion cells (RGCs), bipolar cells and dopaminergic amacrine cells, but not photoreceptors, horizontal cells or cholinergic amacrine cells. The retinas of adult <it>Bim </it>and <it>Bid </it>deficient mice appeared to have no increase in any retinal cell type. <it>Bbc3 </it>deficient mice, either homozygous or heterozygous for a null allele of <it>Bbc3</it>, had an increase in the same cell types as <it>Bax </it>deficient mice. An analogous result may occur in the brain where, similar to <it>Bax </it>deficient mice, <it>Bbc3 </it>deficient mice have a larger gross brain weight compared to wild type mice. In contrast to its developmental role, BBC3 did not appear to be a primary factor in BAX-dependent axonal injury induced neurodegeneration in adult RGCs.</p> <p>Conclusion</p> <p>The regulation of BAX activation in the retina appears to be complex, dependent on the developmental stage of the animal, the nature of the insult and even the type of neuron.</p

    Bell inequality for pairs of particle-number-superselection-rule restricted states

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    Proposals for Bell inequality tests on systems restricted by superselection rules often require operations that are difficult to implement in practice. In this paper, we derive a new Bell inequality, where pairs of states are used to by-pass the superselection rule. In particular, we focus on mode entanglement of an arbitrary number of massive particles and show that our Bell inequality detects the entanglement in the pair when other inequalities fail. However, as the number of particles in the system increases, the violation of our Bell inequality decreases due to the restriction in the measurement space caused by the superselection rule. This Bell test can be implemented using techniques that are routinely used in current experiments.Comment: 9 pages, 6 figures; v2 is the published versio

    ¿El tamaño y la orientación del grupo intruso afecta a la distancia de iniciación al vuelo en aves?

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    Wildlife managers use flight initiation distance (FID), the distance animals flee an approaching predator, to determine set back distances to minimize human impacts on wildlife. FID is typically estimated by a single person; this study examined the effects of intruder number and orientation on FID. Three different group size treatments (solitary person, two people side–by–side, two people one–behind–the–other) were applied to Pied Currawongs (Strepera graculina) and to Crimson Rosellas (Platycerus elegans). Rosellas flushed at significantly greater distances when approached by two people compared to a single person. This effect was not seen in currawongs. Intruder orientation did not influence the FID of either species. Results suggest that intruder number should be better integrated into estimates of set back distance to manage human visitation around sensitive species.Los gestores de la fauna utilizan la distancia de iniciación al vuelo (FID), la distancia a la que los animales huyen cuando se les acerca un depredador, para determinar las distancias de respuesta a fin de minimizar el impacto humano en la fauna. La FID es estimada típicamente por una sola persona; este estudio examinó los efectos del número y de la orientación del intruso en la FID. Se aplicaron tres tratamientos distintos de tamaño del grupo (persona solitaria, dos personas una al lado de la otra, dos personas una detras de la otra) a currawongs cálidos (Strepera graculina) y a pericos elegantes (Platycerus elegans). Los pericos elegantes huían a distancias perceptiblemente mayores cuando se le acercaban dos personas que cuando se le acercaba una sola. Este efecto no fue observado en los currawongs pálidos. La orientación del intruso no influenció en la FID de ninguna especie. Los resultados sugieren que el número de intrusos debería ser considerado en las estimaciones de las distancias de respuesta, para poder gestionar las visitas de personas cerca de especies sensibles
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