Emergent Horizons in the Laboratory

The concept of a horizon known from general relativity describes the loss of causal connection and can be applied to non-gravitational scenarios such as out-of-equilibrium condensed-matter systems in the laboratory. This analogy facilitates the identification and theoretical study (e.g., regarding the trans-Planckian problem) and possibly the experimental verification of "exotic" effects known from gravity and cosmology, such as Hawking radiation. Furthermore, it yields a unified description and better understanding of non-equilibrium phenomena in condensed matter systems and their universal features. By means of several examples including general fluid flows, expanding Bose-Einstein condensates, and dynamical quantum phase transitions, the concepts of event, particle, and apparent horizons will be discussed together with the resulting quantum effects.Comment: 7 pages, 4 figure

Signatures of Planck-scale interactions in the cosmic microwave background?

Based on a rather general low-energy effective action (interacting quantum fields in classical curved space-times), we calculate potential signatures of new physics (such as quantum gravity) at ultra-high energies (presumably the Planck scale) in the anisotropies of the cosmic microwave background. These Planck-scale interactions create non-Gaussian contributions, where special emphasis is laid on the three-point function as the most promising observable, which also allows the discrimination between models violating and those obeying Lorentz invariance. PACS: 98.80.Cq, 04.62.+v, 98.70.Vc, 98.80.Qc.Comment: 4 page

Geo-Biological Investigations on Azooxanthellate Cold-Water Coral Reefs on the Carbonate Mounds Along the Celtic Continental Slope

Northeast Atlantic 2004 Cruise No. 61, Leg 1 April 19 to May 4, 2004, Lisbon – Cor

Probing the potential landscape inside a two-dimensional electron-gas

We report direct observations of the scattering potentials in a two-dimensional electron-gas using electron-beam diffaction-experiments. The diffracting objects are local density-fluctuations caused by the spatial and charge-state distribution of the donors in the GaAs-(Al,Ga)As heterostructures. The scatterers can be manipulated externally by sample illumination, or by cooling the sample down under depleted conditions.Comment: 4 pages, 4 figure

Nonexponetial relaxation of photoinduced conductance in organic field effect transistor

We report detailed studies of the slow relaxation of the photoinduced excess charge carriers in organic metal-insulator-semiconductor field effect transistors consisting of poly(3-hexylthiophene) as the active layer. The relaxation process cannot be physically explained by processes, which lead to a simple or a stretched-exponential decay behavior. Models based on serial relaxation dynamics due to a hierarchy of systems with increasing spatial separation of the photo-generated negative and positive charges are used to explain the results. In order to explain the observed trend, the model is further modified by introducing a gate voltage dependent coulombic distribution manifested by the trapped negative charge carriers.Comment: 17 pages, 3 Figure

Analysis of the impact of dislocation distribution on the breakdown voltage of GaAs-based power varactor diodes

A synchrotron x-ray topography analysis of the impact of the distribution of defects/dislocations on the electrical performance of GaAs power varactor diodes was carried out. Diodes fabricated on or near Liquid Encapsulated Czochralski cellular dislocation networks in the substrate, which are also known to be rich in As precipitates near these cell walls, were observed to have reduced breakdown voltages (VBR). This is consistent with the possibility that the presence of space-charge cylinders surrounding these dislocations gives rise to reduced VBR if they thread a p-n junction; it is also in accord with the possibility that the As precipitates themselves can act as sites for local field enhancement, thus promoting premature avalanche breakdown

Impact of Numerical Methods in Thermal Modeling of Li-Ion Batteries on Temperature Distribution and Computation Time

Thermal battery modeling is important for further battery development and optimization. The temperature strongly influences the performance and aging behavior. In the cell stack, electrochemical processes take place resulting in a large amount of heat release, which, in turn, affects the temperature distribution. Therefore, the main focus is on the cell stack, the most complex structure inside the cell. In particular, the discontinuous and anisotropic material properties represent a major challenge for simulations due to the layering. This work proposes self-developed methods, based on the Finite Volume Method and the Finite Element Method, taking on these challenges. First, for both methods the functionality is verified and numerical convergence is validated. These, and also classical methods, are compared based on test problems with a known analytical solution in view of numerical errors as well as computing time. It if found that their accuracy and efficiency depends strongly on the specific problem, which makes their numerical investigation necessary and inevitable. Second, the methods are evaluated on a specific battery problem. Their results are plausible and correspond to the physical phenomena

Between-day reliability of electromechanical delay of selected neck muscles during performance of maximal isometric efforts

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to assess the between-day reliability of the electromechanical delay (EMD) of selected neck muscles during the performance of maximal isometric contractions in five different directions.</p> <p>Methods</p> <p>Twenty-one physically active males participated in two testing sessions separated by seven to eight days. Using a custom-made fixed frame dynamometer, cervical force and surface electromyography (EMG) were recorded bilaterally from the splenius capitis, upper trapezius and sternocleidomastoid muscles during the performance of efforts in extension, flexion, left and right lateral bending, and protraction. The EMD was extracted using the Teager-Kaiser Energy Operator. Reliability indices calculated for each muscle in each testing direction were: the difference in scores between the two testing sessions and corresponding 95% confidence intervals, the standard error of measurement (SEM) and intra-class correlation coefficients (ICC).</p> <p>Results</p> <p>EMD values showed no evidence of systematic difference between the two testing sessions across all muscles and testing directions. The SEM for extension, flexion and lateral bending efforts ranged between 2.5 ms to 4.8 ms, indicating a good level of measurement precision. For protraction, SEM values were higher and considered to be imprecise for research and clinical purposes. ICC values for all muscles across all testing directions ranged from 0.23 to 0.79.</p> <p>Conclusion</p> <p>EMD of selected neck muscles can be measured with sufficient precision for the assessment of neck muscle function in an athletic population in the majority of directions tested.</p

Blockade of advanced glycation end product formation attenuates bleomycin-induced pulmonary fibrosis in rats

<p>Abstract</p> <p>Background</p> <p>Advanced glycation end products (AGEs) have been proposed to be involved in pulmonary fibrosis, but its role in this process has not been fully understood. To investigate the role of AGE formation in pulmonary fibrosis, we used a bleomycin (BLM)-stimulated rat model treated with aminoguanidine (AG), a crosslink inhibitor of AGE formation.</p> <p>Methods</p> <p>Rats were intratracheally instilled with BLM (5 mg/kg) and orally administered with AG (40, 80, 120 mg/kg) once daily for two weeks. AGEs level in lung tissue was determined by ELISA and pulmonary fibrosis was evaluated by Ashcroft score and hydroxyproline assay. The expression of heat shock protein 47 (HSP47), a collagen specific molecular chaperone, was measured with RT-PCR and Western blot. Moreover, TGFβ1 and its downstream Smad proteins were analyzed by Western blot.</p> <p>Results</p> <p>AGEs level in rat lungs, as well as lung hydroxyproline content and Ashcroft score, was significantly enhanced by BLM stimulation, which was abrogated by AG treatment. BLM significantly increased the expression of HSP47 mRNA and protein in lung tissues, and AG treatment markedly decreased BLM-induced HSP47 expression in a dose-dependent manner (p < 0.05). In addition, AG dose-dependently downregulated BLM-stimulated overexpressions of TGFβ1, phosphorylated (p)-Smad2 and p-Smad3 protein in lung tissues.</p> <p>Conclusion</p> <p>These findings suggest AGE formation may participate in the process of BLM-induced pulmonary fibrosis, and blockade of AGE formation by AG treatment attenuates BLM-induced pulmonary fibrosis in rats, which is implicated in inhibition of HSP47 expression and TGFβ/Smads signaling.</p