University of Hamburg

About: University of Hamburg is a education organization based out in Hamburg, Germany. It is known for research contribution in the topics: Population & Laser. The organization has 45564 authors who have published 89286 publications receiving 2850161 citations. The organization is also known as: Hamburg University.

Extracellular matrix molecules and synaptic plasticity

Abstract: Interactions between cells and the extracellular matrix (ECM) have long been accepted to have pivotal roles in neural development and regeneration. Recent data also support the involvement of several ECM molecules in synaptic plasticity. Here, we review the present knowledge of the underlying mechanisms. These include interactions with cell surface receptors for ECM molecules coupled to the cytoskeleton and tyrosine kinase activities, and interactions with ion channels or neurotransmitter receptors. We hypothesize that ECM molecules derived from neurons and glia might also shape synaptic plasticity through regulation of organelle trafficking, and by imposing diffusion constraints for neurotransmitters and trophic factors.

On determining developmental stages in natural second language acquisition

Abstract: Research on Second Language (L2) Acquisition, over the past ten years, has undergone substantial changes by shifting its focus of interest away from an analysis of linguistic structures alone, concentrating more on the learner himself or, rather, on the process of learning. It had become obvious that one of the major shortcomings in contrastive studies as well as in the usual kind of error analysis is that they lack thorough investigation of factors which determine the kind of approach a learner may take to acquire a second language. This again implies that it is more fruitful to study the process of learning itself instead of merely analysing its outputs. It is by now widely accepted that the learner takes an active part in the learning process and does not merely get trapped in structural gaps which linguists may find when comparing the source language (the learner's L1) and the target language (L2).

Exact Spectrum of Anomalous Dimensions of Planar N = 4 Supersymmetric Yang-Mills Theory

Abstract: We present a set of functional equations defining the anomalous dimensions of arbitrary local single trace operators in planar $\mathcal{N}=4$ supersymmetric Yang-Mills theory. It takes the form of a $Y$ system based on the integrability of the dual superstring $\ensuremath{\sigma}$ model on the five-dimensional anti--de Sitter space (${\mathrm{AdS}}_{5}\ifmmode\times\else\texttimes\fi{}{\mathrm{S}}^{5}$) background. This $Y$ system passes some very important tests: it incorporates the full asymptotic Bethe ansatz at large length of operator $L$, including the dressing factor, and it confirms all recently found wrapping corrections. The recently proposed ${\mathrm{AdS}}_{4}/\mathrm{\text{three-dimensional}}$ conformal field theory duality is also treated in a similar fashion.

Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV

Abstract: Improved jet energy scale corrections, based on a data sample corresponding to an integrated luminosity of 19.7 fb^(-1) collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 8 TeV, are presented. The corrections as a function of pseudorapidity η and transverse momentum p_T are extracted from data and simulated events combining several channels and methods. They account successively for the effects of pileup, uniformity of the detector response, and residual data-simulation jet energy scale differences. Further corrections, depending on the jet flavor and distance parameter (jet size) R, are also presented. The jet energy resolution is measured in data and simulated events and is studied as a function of pileup, jet size, and jet flavor. Typical jet energy resolutions at the central rapidities are 15–20% at 30 GeV, about 10% at 100 GeV, and 5% at 1 TeV. The studies exploit events with dijet topology, as well as photon+jet, Z+jet and multijet events. Several new techniques are used to account for the various sources of jet energy scale corrections, and a full set of uncertainties, and their correlations, are provided. The final uncertainties on the jet energy scale are below 3% across the phase space considered by most analyses (p_T > 30 GeV and 0|η| 30 GeV is reached, when excluding the jet flavor uncertainties, which are provided separately for different jet flavors. A new benchmark for jet energy scale determination at hadron colliders is achieved with 0.32% uncertainty for jets with p_T of the order of 165–330 GeV, and |η| < 0.8.

Optical coherence tomography in multiple sclerosis: a systematic review and meta-analysis

Abstract: Summary Optical coherence tomography (OCT) is a new method that could aid analysis of neurodegeneration in multiple sclerosis (MS) by capturing thinning of the retinal nerve fibre layer (RNFL). Meta-analyses of data for time domain OCT show RNFL thinning of 20·38 μm (95% CI 17·91–22·86, n=2063, p