Number and position of visual stimuli as determinants of reaction time in schizophrenia.

Notes that RT in normal Ss has been shown to be linearly related to stimulus complexity, defined as the log of the number of equally probable stimuli to which a response may be made. Data from an earlier study of 40 short- and long-term paranoid and nonparanoid male schizophrenics and 10 male hospital employees were reanalyzed and compared with P. Venable's (see record 1959-10789-001) study of schizophrenic deficit. Although experimental procedures were dissimilar, both studies found that increased complexity did not result in schizophrenics having steeper regression slopes than normal Ss. Consideration of the position of the critical stimulus, however, clearly indicated that long-term, nonparanoid schizophrenics narrow attention to central cues when confronted by an increase in complexity. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Viscous Sintering with a Pore-Size Distribution and Rigid Inclusions

The model developed for sintering of a bimodal pore-size distribution is generalized to describe an arbitrary distribution. The model is further extended to allow for the presence of nonsintering (i.e., rigid) inclusions. This analysis uses the self-consistent approach that takes account of the local stresses created by differential sintering rates.     

Beyond Heparinization: Design of Highly Potent Thrombin Inhibitors Suitable for Surface Coupling

During extracorporeal circulation, when blood comes in contact with artificial surfaces, patients receive a standard treatment with anticoagulants to avoid blood coagulation. Dialysis patients in particular are systemically treated with heparin up to four times a week, causing a high burden for the body. For potential anticoagulant modification of external materials, such as dialysis equipment, a series of highly potent thrombin inhibitors was developed. All inhibitors share the general formula arylsulfonyl‐P3‐Pro‐4‐amidinobenzylamide, where P3 is glycyl or a trifunctional amino acid residue in L ‐configuration. Among this series, several derivatives inhibit thrombin with K_i values of less than 1 nM . Specificity measurements revealed that this inhibitor type is highly specific for thrombin with negligible activity against related trypsin‐like serine proteases. X‐ray analysis of the most potent analogue in complex with thrombin demonstrated that the N‐terminal arylsulfonyl group occupies the aryl binding site, whereas the P3 side chain is directed into the solvent and therefore is well suited for further coupling. Based on their in vitro profile, these inhibitors are suitable candidates for the development of hemocompatible materials with anticoagulant properties.     

Untersuchungen zur Homogenität von Bauwerksteilen mit Lasertechniken

Investigations concerning homogeneity of building parts by laser techniques. The subproject B1 “Diagnostics and Quality Control by Non‐Destructive, Contactless Testing Techniques” is working within the CRC 524 on the procedural and measurement technological evolutionary development of the conventional ultrasonic through‐transmission method towards an optical measuring method by application of laser technologies. The aim is the determination of the distribution of elastic characteristic parameters for the evaluation of laboratory test specimens in investigations on durability of concrete and for the actual state of construction elements in the course of revitalising buildings. In this case, a laser induced sound excitation takes place by means of an Nd:YAG‐laser. The sound waves that have been influenced by the investigation object are detected by a laser vibrometer. By applying these methods, both a high lasing rate and a high achievable data density are to be expected since the laser beams in both systems can be deflected optically by means of scanners. Furthermore, a surveying‐technological approach for sound path determination at each pair of measuring points has been developed, which can also be used for the conventional application of the ultrasonic through‐transmission method.     

Retinal neurostimulator for a multifocal vision prosthesis.

A neurostimulator application-specific integrated circuit (ASIC) with scalable circuitry that can stimulate 14 channels, has been developed for an epi-retinal vision prosthesis. This ASIC was designed to allow seven identical units to be connected to control up to 98 channels, with the ability to stimulate 14 electrodes simultaneously. The neurostimulator forms part of a vision prosthesis, designed to restore vision to patients who have lost their sight due to retinal diseases such as retinitis pigmentosa and macular degeneration. For charge balance, the neurostimulator was designed to stimulate with current sources and sinks operating together, and with the ability to drive a hexagonal mosaic of electrodes to reduce the electrical crosstalk that occurs when multiple bipolar stimulation sites are active simultaneously. A hexagonal mosaic of electrodes surrounds each stimulation site and has been shown to effectively isolate each site, increasing the ability to inject localized independent charge into multiple regions simultaneously.     

Brain-computer communication: motivation, aim, and impact of exploring a virtual apartment.

The step away from a synchronized or cue-based brain-computer interface (BCI) and from laboratory conditions towards real world applications is very important and crucial in BCI research. This work shows that ten naive subjects can be trained in a synchronous paradigm within three sessions to navigate freely through a virtual apartment, whereby at every junction the subjects could decide by their own, how they wanted to explore the virtual environment (VE). This virtual apartment was designed similar to a real world application, with a goal-oriented task, a high mental workload, and a variable decision period for the subject. All subjects were able to perform long and stable motor imagery over a minimum time of 2 s. Using only three electroencephalogram (EEG) channels to analyze these imaginations, we were able to convert them into navigation commands. Additionally, it could be demonstrated that motivation is a very crucial factor in BCI research; motivated subjects perform much better than unmotivated ones.     

Nonlinear buckling analysis of vertical wafer probe technology

Due to the demand of the industry for an increase of the number of I/Os, while decreasing the die size, the bond pads had to shrink and design restrictions for the active structures underneath had to fall. This leads to new challenges for the electrical probing and the mechanical robustness of the under-pad structures. This paper presents analytical and numerical simulation approaches for predicting the force/travel relation of buckling beam-probes that are used for testing the electrical functionality of back-end-of-line (BEOL) interconnect system underneath a chip pad. For this purpose we investigate, first, in a closed-form manner, the elastic stability of the probe needle according to the large deflection theory of buckled bars. Second, we determine, for a specific geometry of the beam, the probe forces as functions of the probe card overdrive by using the closed-form methods as well as finite-element simulations. The results are finally compared to that obtained in (probe card) experiments.     

Three-dimensional echo-planar cine imaging of cerebral blood supply using arterial spin labeling

Objective

Echo-planar imaging (EPI) with CYlindrical Center-out spatiaL Encoding (EPICYCLE) is introduced as a novel hybrid three-dimensional (3D) EPI technique. Its suitability for the tracking of a short bolus created by pseudo-continuous arterial spin labeling (pCASL) through the cerebral vasculature is demonstrated.

Materials and methods

EPICYCLE acquires two-dimensional planes of k-space along center-out trajectories. These “spokes” are rotated from shot to shot about a common axis to encode a k-space cylinder. To track a bolus of labeled blood, the same subset of evenly distributed spokes is acquired in a cine fashion after a short period of pCASL. This process is repeated for all subsets to fill the whole 3D k-space of each time frame.

Results

The passage of short pCASL boluses through the vasculature of a 3D imaging slab was successfully imaged using EPICYCLE. By choosing suitable sequence parameters, the impact of slab excitation on the bolus shape could be minimized. Parametric maps of signal amplitude, transit time, and bolus width reflected typical features of blood transport in large vessels.

Conclusion

The EPICYCLE technique was successfully applied to track a short bolus of labeled arterial blood during its passage through the cerebral vasculature.