Zur härtung von diandiglycidylether mit anhydridmodifizierten phenolischen härtern und zu vergleichbaren in situ-reaktionen

The curing of diglycidyl ether of bisphenol A (DGEBA) with 2,6-dimethylol-p-cresol modified by hexahydrophthalic acid anhydride was investigated and compared with the analogous in situ curing of DGEBA, hexahydrophthalic acid anhydride and 2,6-dimethylol-p-cresol. The chemical reactions were investigated by means of titration and different spectroscopic and chromatographic methods. It was examined whether the less complicated and therefore cheaper in situ reaction delivers postcured products with equal or better properties. Furthermore, it was investigated whether the results are similar using technical phenolic hardeners.     

Holocaust survivors and escapees: Their strengths.

The conclusions clinicians have drawn about Holocaust survivors over the last 50 yrs differ sharply from researchers' findings. It is important to evaluate these discrepancies since different perceptions of survivors affect treatment approaches. The researchers' view, stressing the survivor's resilience and resourcefulness, contrasts with clinical impressions centering on a survivor syndrome involving deep emotional disturbances as residues of the Holocaust experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropeptidergic organization of the suprachiasmatic nucleus in the blind mole rat (Spalax ehrenbergi)

The blind mole rat, Spalax, is a subterranean rodent with atrophied, subcutaneous eyes. Whereas most of the visual system is highly degenerated, the retino-hypothalamic pathway in this species has remained intact. Although Spalax is considered to be visually blind, circadian locomotor rhythms are entrained by the light/dark cycle. In the present study we used anterograde tracing techniques to demonstrate retinal afferents to the suprachiasmatic nucleus (SCN) and immunohistochemistry to examine the distribution of neuropeptides that are known to be involved in the regulation or expression of circadian rhythmicity. Based on the localization of retinal afferents and neuropeptides, the SCN can be divided into two subdivisions. The ventral region, which receives retinal afferents, also contains vasoactive intestinal polypeptide (VIP)-containing neurons, and fibers that are immunopositive to neuropeptide Y (NPY) and serotonin (5-HT). The dorsal region contains vasopressinergic neurons, but this latter cell population is extremely sparse compared to that described in other rodents. The dorsal region is also characterized by numerous VIP-immunoreactive fibers. The presence of NPY and 5-HT fibers suggests that the SCN receives afferent projections from the intergeniculate leaflet and from the raphe nuclei, respectively. These neuroanatomical results, together with previous studies of behavior, visual tract tracing, and immediate early gene expression, confirm that an endogenous clock and the capacity for light entrainment of circadian rhythms are conserved in the blind mole rat.     

IT capability and organizational performance: the roles of business process agility and environmental factors

The business value of information technology (IT) has been one of the top concerns of both practitioners and scholars for decades. Numerous studies have documented the positive effects of IT capability on organizational performance but our knowledge of the processes through which such gains are achieved remains limited due to a lack of focus on the business environment. Such a linkage therefore remains the subject of debate in the information systems literature. In this study, we fill this gap by investigating the mediating role of business process agility and the moderating roles of environmental factors. On the basis of matched survey data obtained from 214 IT and business executives from manufacturing firms in China, our analyses show that even though firm-wide IT capability presents the characteristics of rarity, appropriability, non-reproducibility, and non-substitutability, its impact on organizational performance is fully mediated by business process agility. Our results also show that the impact of the environment is multifaceted and nuanced. In particular, environmental hostility weakens the effect of IT capability on business process agility, while environmental complexity strengthens it. The theoretical and practical implications of this study, and its limitations, are also discussed.     

A competitive study of the pseudoflow algorithm for the minimum <Emphasis Type="Italic">s</Emphasis>–<Emphasis Type="Italic">t</Emphasis> cut problem in vision applications

Rapid advances in image acquisition and storage technology underline the need for real-time algorithms that are capable of solving large-scale image processing and computer-vision problems. The minimum s–t cut problem, which is a classical combinatorial optimization problem, is a prominent building block in many vision and imaging algorithms such as video segmentation, co-segmentation, stereo vision, multi-view reconstruction, and surface fitting to name a few. That is why finding a real-time algorithm which optimally solves this problem is of great importance. In this paper, we introduce to computer vision the Hochbaum’s pseudoflow (HPF) algorithm, which optimally solves the minimum s–t cut problem. We compare the performance of HPF, in terms of execution times and memory utilization, with three leading published algorithms: (1) Goldberg’s and Tarjan’s Push-Relabel; (2) Boykov’s and Kolmogorov’s augmenting paths; and (3) Goldberg’s partial augment-relabel. While the common practice in computer-vision is to use either BK or PRF algorithms for solving the problem, our results demonstrate that, in general, HPF algorithm is more efficient and utilizes less memory than these three algorithms. This strongly suggests that HPF is a great option for many real-time computer-vision problems that require solving the minimum s–t cut problem.     

Automatic boosting of cross-product coverage using Bayesian networks

Closing the feedback loop from coverage data to the stimuli generator is one of the main challenges in the verification process. Typically, verification engineers with deep domain knowledge manually prepare a set of stimuli generation directives for that purpose. Bayesian networks based CDG (coverage directed generation) systems have been successfully used to assist the process by automatically closing this feedback loop. However, constructing these CDG systems requires manual effort and a certain amount of domain knowledge from a machine learning specialist. We propose a new method that boosts coverage in the early stages of the verification process with minimal effort, namely a fully automatic construction of a CDG system that requires no domain knowledge. Experimental results on a real-life cross-product coverage model demonstrate the efficiency of the proposed method.     

Hybrid visualization for white matter tracts using triangle strips and point sprites

Diffusion tensor imaging is of high value in neurosurgery, providing information about the location of white matter tracts in the human brain. For their reconstruction, streamline techniques commonly referred to as fiber tracking model the underlying fiber structures and have therefore gained interest. To meet the requirements of surgical planning and to overcome the visual limitations of line representations, a new real-time visualization approach of high visual quality is introduced. For this purpose, textured triangle strips and point sprites are combined in a hybrid strategy employing GPU programming. The triangle strips follow the fiber streamlines and are textured to obtain a tube-like appearance. A vertex program is used to orient the triangle strips towards the camera. In order to avoid triangle flipping in case of fiber segments where the viewing and segment direction are parallel, a correct visual representation is achieved in these areas by chains of point sprites. As a result, a high quality visualization similar to tubes is provided allowing for interactive multimodal inspection. Overall, the presented approach is faster than existing techniques of similar visualization quality and at the same time allows for real-time rendering of dense bundles encompassing a high number of fibers, which is of high importance for diagnosis and surgical planning.     

Genome size and base composition in Oryzaephilus surinamensis (Coleoptera: Sylvanidae) and differences between native (feral) and silo pest populations in Israel

In this study, flow cytometry was used for assessing and comparing the genome size (GS) and the whole genome base composition (AT/GC ratio) of the saw-toothed grain beetle Oryzaephilus surinamensis (L.). In addition, the presence and frequency of endosymbiotic Wolbachia bacteria was studied. The haploid GS was estimated to lie within the range of 151.5-154 Mbp in O. surinamensis, making it the smallest value of haploid GS known among beetles. Furthermore, it was found that in eight silo pest populations GS was significantly smaller than in eight feral (native) populations obtained from fallen oak acorns. The ability of O. surinamensis to colonize different habitats globally could be connected with an unusually AT-rich (for an invertebrate) genome (AT-base content ranging from 68 to 76%). Native (feral) populations of O. surinamensis appear to have genetically diverged from the storage-pest populations tested. Larvae of pest origin survived better than larvae of native (feral) origin under laboratory conditions, which resembled silo conditions more than natural habitats.     

The Key Enzyme of the Sialic Acid Metabolism Is Involved in Embryoid Body Formation and Expression of Marker Genes of Germ Layer Formation

The bi-functional enzyme UDP-N-acetyl-2-epimerase/N-acetylmannosamine kinase (GNE) is the key enzyme of the sialic acid biosynthesis. Sialic acids are negatively charged nine carbon amino sugars and are found on most glycoproteins and many glycolipids in terminal positions, where they are involved in a variety of biological important molecular interactions. Inactivation of the GNE by homologous recombination results in early embryonic lethality in mice. Here, we report that GNE-deficient embryonic stem cells express less differentiation markers compared to wild-type embryonic stem cells. As a result, GNE-deficient embryonic stem cells fail to form proper embryoid bodies (EB) within the first day of culture. However, when culturing these cells in the presence of sialic acids for three days, also GNE-deficient embryonic stem cells form normal EBs. In contrast, when culturing these cells in sialic acid reduced medium, GNE-deficient embryonic stem cells proliferate faster and form larger EBs without any change in the expression of markers of the germ layers.