7,555 research outputs found
Die Ausgrabungen von Kalkriese und die Rekonstruktion des Verlaufes der Varuskatastrophe im Jahre 9 n. Chr.
No Abstract
Die Ausgrabungen von Kalkriese und die Rekonstruktion des Verlaufes der Varuskatastrophe im Jahre 9 n. Chr.
No Abstract
Two physical characteristics of numerical apparent horizons
This article translates some recent results on quasilocal horizons into the
language of general relativity so as to make them more useful to
numerical relativists. In particular quantities are described which
characterize how quickly an apparent horizon is evolving and how close it is to
either equilibrium or extremality.Comment: 6 pages, 2 figures, conference proceedings loosely based on talk
given at Theory Canada III (Edmonton, Alberta, 2007). V2: Minor changes in
response to referees comments to improve clarity and fix typos. One reference
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Phonon-assisted optical absorption in BaSnO3 from first principles
Convex Independence in Permutation Graphs
A set C of vertices of a graph is P_3-convex if every vertex outside C has at
most one neighbor in C. The convex hull \sigma(A) of a set A is the smallest
P_3-convex set that contains A. A set M is convexly independent if for every
vertex x \in M, x \notin \sigma(M-x). We show that the maximal number of
vertices that a convexly independent set in a permutation graph can have, can
be computed in polynomial time
Genetic differentiation in Oxalis (Oxalidaceae): A tale of rarity and abundance in the Cape Floristic Region
AbstractOxalis L. is the largest and most diverse genus in the family Oxalidaceae. Within southern Africa, Oxalis is represented by ca. 270 taxa, the majority occurring in the Cape Region. Although many of the species are widespread, ca. 25% are considered rare. The aim of this paper is to assess the degree of genetic differentiation between two rare and highly localized species (Oxalis hygrophila Dreyer and Oxalis oligophylla Salter) and the more widespread Oxalis tomentosa L.f. For comparative purposes, we also include Oxalis purpurea L., one of the most widely distributed species in South Africa. Chloroplast sequences of the trnH/psbA spacer revealed low genetic diversity for O. oligophylla and O. tomentosa compared to the widespread O. purpurea. High genetic diversity in O. purpurea might, in combination with other ecological and reproductive factors, account for the success of this species. In contrast, low variation might contribute to rarity in O. oligophylla and ultimately ground O. tomentosa to become rare. The latter two species were not monophyletic with a shared haplotype. Coalescent modelling revealed low levels of gene flow (<1 migrant per generation) between them and we argue that the genetic pattern is the result of the retention of ancestral polymorphism following a recent divergence
Molecular basis of glutamate toxicity in retinal ganglion cells
Loss of retinal ganglion cells (RGCs) is a hallmark of many ophthalmic diseases including glaucoma, retinal ischemia due to central artery occlusion, anterior ischemic optic neuropathy and may be significant in optic neuritis, optic nerve trauma, and AIDS. Recent research indicates that neurotoxicity is caused by excessive stimulation of receptors for excitatory amino acids (EAAs). In particular, the amino acid glutamate has been shown to act as a neurotoxin which exerts its toxic effect on RGCs predominantly through the N-methyl-d-aspartate (NMDA) subtype of glutamate receptor. NMDA-receptor-mediated toxicity in RGCs is dependent on the influx of extracellular Ca2+. The increase in [Ca2+]i acts as a second messenger that sets in motion the cascade leading to eventual cell death. Glutamate stimulates its own release in a positive feedback loop by its interaction with the non-NMDA receptor subtypes. Ca2+-induced Ca2+ release and further influx of Ca2+ through voltage-gated Ca2+ channels after glutamate-induced depolarization contribute to glutamate toxicity. In vitro and in vivo studies suggest that the use of selective NMDA receptor antagonists or Ca2+ channel blockers should be useful in preventing or at least abating neuronal loss in the retina. Of particular importance for future clinical use of NMDA receptor antagonists in the treatment of acute vascular insults is the finding that some drugs can prevent glutamate-induced neurotoxicity, even when administered a few hours after the onset of retinal ischemia
Long-term stability of short-term intensive language–action therapy in chronic aphasia: A 1–2 year follow-up study
Background. Intensive aphasia therapy can improve language functions in chronic aphasia over a short therapy interval of 2-4 weeks. For one intensive method, intensive language-action therapy, beneficial effects are well documented by a range of randomized controlled trials. However, it is unclear to date whether therapy-related improvements are maintained over years. Objective. The current study aimed at investigating long-term stability of ILAT treatment effects over circa 1-2 years (8-30 months). Methods. 38 patients with chronic aphasia participated in ILAT and were re-assessed at a follow-up assessment 8-30 months after treatment, which had been delivered 6-12.5 hours per week for 2-4 weeks. Results. A standardized clinical aphasia battery, the Aachen Aphasia Test, revealed significant improvements with ILAT that were maintained for up to 2.5 years. Improvements were relatively better preserved in comparatively young patients (<60 years). Measures of communicative efficacy confirmed improvements during intensive therapy but showed inconsistent long-term stability effects. Conclusions. The present data indicate that gains resulting from intensive speech-language therapy with ILAT are maintained up to 2.5 years after the end of treatment. We discuss this novel finding in light of a possible move from sparse to intensive therapy regimes in clinical practice
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