13,648 research outputs found
Dimensional Effects on the Density of States in Systems with Quasi-Relativistic Dispersion Relations and Potential Wells
Motivated by the recent discoveries of materials with quasi-relativistic
dispersion relations, we determine densities of states in materials with low
dimensional substructures and relativistic dispersion relations. We find that
these dimensionally hybrid systems yield quasi-relativistic densities of states
that are a superposition of the corresponding two- and three-dimensional
densities of states.Comment: To be submitted to the Canadian Journal of Physics, 8 pages, 4 figue
Gravity and the Newtonian limit in the Randall-Sundrum model
We point out that the gravitational evolution equations in the
Randall-Sundrum model appear in a different form than hitherto assumed. As a
consequence, the model yields a correct Newtonian limit in a novel manner.Comment: 9 pages, LaTeX, sign changed and references added. We have also
appended a remark on the compatibility of the 4D Poincare invariant metric of
Randall and Sundrum with the boundary equation
Expertise with non-speech 'auditory Greebles' recruits speech-sensitive cortical regions
Regions of the human temporal lobe show greater activation for speech than for other sounds. These differences may reflect intrinsically specialized domain-specific adaptations for processing speech, or they may be driven by the significant expertise we have in listening to the speech signal. To test the expertise hypothesis, we used a video-game-based paradigm that tacitly trained listeners to categorize acoustically complex, artificial nonlinguistic sounds. Before and after training, we used functional MRI to
measure how expertise with these sounds modulated temporal lobe activation. Participants’ ability to explicitly categorize the nonspeech sounds predicted the change in pretraining to posttraining activation in speech-sensitive regions of the left posterior superior temporal sulcus, suggesting that emergent auditory expertise may help drive this functional regionalization. Thus, seemingly domain-specific patterns of neural activation in higher cortical regions may be driven in part by experience-based
restructuring of high-dimensional perceptual space
Multiple uses of water in irrigated areas: a case study from Sri Lanka
Water management / Water allocation / Water use efficiency / Irrigated farming / Water resources development / Water policy / Water quality / Domestic water / Water users' associations / Water rights / Gender / Households / Pricing / Water costs / Case studies / Sri Lanka / Kirindi Oya
Curvature corrections in DGP brane cosmology
We consider a DGP inspired brane scenario where the action on the brane is
augmented by a function of the Ricci scalar, . The cosmological
implications that such a scenario entails are examined for and shown to
be consistent with a universe expanding with power-law acceleration. It is
shown that two classes of solutions exist for the usual FRW metric and small
Hubble radii. When the Hubble radius becomes larger, we either have a
transition to a fully 5D regime or to a self-inflationary solution which
produces a late accelerated expansion such that the radius becomes a function
of .Comment: 11 pages, 2 figure
Characterization of a set of abdominal neuroendocrine cells that regulate stress physiology using colocalized diuretic peptides in Drosophila
Multiple neuropeptides are known to regulate water and ion balance in Drosophila melanogaster. Several of these peptides also have other functions in physiology and behavior. Examples are corticotropin-releasing factor-like diuretic hormone (diuretic hormone 44; DH44) and leucokinin (LK), both of which induce fluid secretion by Malpighian tubules (MTs), but also regulate stress responses, feeding, circadian activity and other behaviors. Here, we investigated the functional relations between the LK and DH44 signaling systems. DH44 and LK peptides are only colocalized in a set of abdominal neurosecretory cells (ABLKs). Targeted knockdown of each of these peptides in ABLKs leads to increased resistance to desiccation, starvation and ionic stress. Food ingestion is diminished by knockdown of DH44, but not LK, and water retention is increased by LK knockdown only. Thus, the two colocalized peptides display similar systemic actions, but differ with respect to regulation of feeding and body water retention. We also demonstrated that DH44 and LK have additive effects on fluid secretion by MTs. It is likely that the colocalized peptides are coreleased from ABLKs into the circulation and act on the tubules where they target different cell types and signaling systems to regulate diuresis and stress tolerance. Additional targets seem to be specific for each of the two peptides and subserve regulation of feeding and water retention. Our data suggest that the ABLKs and hormonal actions are sufficient for many of the known DH44 and LK functions, and that the remaining neurons in the CNS play other functional roles
- …