Rapid encoding of task regularities in the human hippocampus guides sensorimotor timing

The brain encodes the statistical regularities of the environment in a task-specific yet flexible and generalizable format. Here, we seek to understand this process by bridging two parallel lines of research, one centered on sensorimotor timing, and the other on cognitive mapping in the hippocampal system. By combining functional magnetic resonance imaging (fMRI) with a fast-paced time-to-contact (TTC) estimation task, we found that the hippocampus signaled behavioral feedback received in each trial as well as performance improvements across trials along with reward-processing regions. Critically, it signaled performance improvements independent from the tested intervals, and its activity accounted for the trial-wise regression-to-the-mean biases in TTC estimation. This is in line with the idea that the hippocampus supports the rapid encoding of temporal context even on short time scales in a behavior-dependent manner. Our results emphasize the central role of the hippocampus in statistical learning and position it at the core of a brain-wide network updating sensorimotor representations in real time for flexible behavior

One-fifth-scale and full-scale fuel element rocking tests. [HTGR]

Using /sup 1///sub 5/-scale and /sup 1///sub 1/-scale (prototype H451) fuel elements, one, two, or three stacked elements on a clamped base element were rocked from an initial release position. Relative displacement, rock-down loads, and dowel pin shear forces were measured. A scaled comparison between /sup 1///sub 5/-scale and /sup 1///sub 1/-scale results was made to evaluate the model scaling laws, and an error analysis was performed to assess the accuracy and usefulness of the test data

Исследование влияния технологического процесса изготовления обмоток на дефектность корпусной изоляции асинхронных двигателей

В работе проведено исследование влияния колебаний режимов работы статорообмоточных станков WST-660 и пазоизолировочных станков ИПС-3 на дефектность корпусной изоляции. Получены математические модели дефектообразования в корпусной изоляции обмотки с учетом режимов работы технологического оборудования и качества материала корпусной изоляции в состоянии поставки. Установлено, что изменением режимов работы технологического оборудования можно добиться требуемого качества корпусной изоляции при максимальной производительности оборудования

Comparison of nanoparticular hydroxyapatite pastes of different particle content and size in a novel scapula defect model

Nanocrystalline hydroxyapatite (HA) has good biocompatibility and the potential to support bone formation. It represents a promising alternative to autologous bone grafting, which is considered the current gold standard for the treatment of low weight bearing bone defects. The purpose of this study was to compare three bone substitute pastes of different HA content and particle size with autologous bone and empty defects, at two time points (6 and 12 months) in an ovine scapula drillhole model using micro-CT, histology and histomorphometry evaluation. The nHA-LC (38% HA content) paste supported bone formation with a high defect bridging-rate. Compared to nHA-LC, Ostim(®) (35% HA content) showed less and smaller particle agglomerates but also a reduced defect bridging-rate due to its fast degradation The highly concentrated nHA-HC paste (48% HA content) formed oversized particle agglomerates which supported the defect bridging but left little space for bone formation in the defect site. Interestingly, the gold standard treatment of the defect site with autologous bone tissue did not improve bone formation or defect bridging compared to the empty control. We concluded that the material resorption and bone formation was highly impacted by the particle-specific agglomeration behaviour in this study

Quadrupole correlations and inertial properties of rotating nuclei

The contribution of quantum shape fluctuations to inertial properties of rotating nuclei has been analyzed for QQ-nuclear interaction using the random phase approximation (RPA). The different recipes to treat the cranking mean field plus RPA problem are considered. The effects of the dN=2 quadrupole matrix elements and the role of the volume conservation condition are discussed.Comment: 14 pages, 7 figures, To be published in J. Phys. G: Nucl. Phy

Determination of the Michel Parameters rho, xi, and delta in tau-Lepton Decays with tau --> rho nu Tags

Using the ARGUS detector at the $e^+ e^-$ storage ring DORIS II, we have measured the Michel parameters $\rho$, $\xi$, and $\xi\delta$ for $\tau^{\pm}\to l^{\pm} \nu\bar\nu$ decays in $\tau$-pair events produced at center of mass energies in the region of the $\Upsilon$ resonances. Using $\tau^\mp \to \rho^\mp \nu$ as spin analyzing tags, we find $\rho_{e}=0.68\pm 0.04 \pm 0.08$, $\xi_{e}= 1.12 \pm 0.20 \pm 0.09$, $\xi\delta_{e}= 0.57 \pm 0.14 \pm 0.07$, $\rho_{\mu}= 0.69 \pm 0.06 \pm 0.08$, $\xi_{\mu}= 1.25 \pm 0.27 \pm 0.14$ and $\xi\delta_{\mu}= 0.72 \pm 0.18 \pm 0.10$. In addition, we report the combined ARGUS results on $\rho$, $\xi$, and $\xi\delta$ using this work und previous measurements.Comment: 10 pages, well formatted postscript can be found at http://pktw06.phy.tu-dresden.de/iktp/pub/desy97-194.p

Mutagenesis of the NaChBac sodium channel discloses a functional role for a conserved S6 asparagine

Asparagine is conserved in the S6 transmembrane segments of all voltage-gated sodium, calcium, and TRP channels identified to date. A broad spectrum of channelopathies including cardiac arrhythmias, epilepsy, muscle diseases, and pain disorders is associated with its mutation. To investigate its effects on sodium channel functional properties, we mutated the simple prokaryotic sodium channel NaChBac. Electrophysiological characterization of the N225D mutant reveals that this conservative substitution shifts the voltage-dependence of inactivation by 25 mV to more hyperpolarized potentials. The mutant also displays greater thermostability, as determined by synchrotron radiation circular dichroism spectroscopy studies of purified channels. Based on our analyses of high-resolution structures of NaChBac homologues, we suggest that the side-chain amine group of asparagine 225 forms one or more hydrogen bonds with different channel elements and that these interactions are important for normal channel function. The N225D mutation eliminates these hydrogen bonds and the structural consequences involve an enhanced channel inactivation