Rezensionen

Ohne Zusammenfassung     

The discriminative stimulus and its reputation: Role in the instigation of drug abuse.

The conditions that permitted the oral self-administration of a drug solution to develop as a reinforcing event for rats, so that a drug solution was preferred to a concurrently available vehicle (water), were elucidated. The genesis of a preference for a solution depended importantly on a history wherein the discriminative stimulus (a light SD) present in proximity to the drug-solution location had been associated with the self-administration of an ethanol solution. Once the SD was established, it stably determined fluid choice even if that fluid was a 2nd source of water. Results indicate that the sources of persistence and malleability of drug abuse behavior may lie in the instigating properties of established discriminative stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrated optics 4*4 switch matrix with digital optical switches

Reports on the first 4*4 switch matrix with digital optical switches as switch elements. The matrix is arranged in a tree structure, and comprises 24 switch elements and is pigtailed and packaged.<>     

Comparison of immunohistochemistry, acid-fast staining, and cultivation for detection of Mycobacterium paratuberculosis in goats

Forty-seven paired specimens of ileum and mesenterial lymph nodes from goats originating from 2 herds with paratuberculosis were investigated. Culture of the specimens for Mycobacterium paratuberculosis was compared with Ziehl-Neelsen staining and with immunohistochemical tests on paraffin-embedded tissue sections, using a M. paratuberculosis immune serum and an avidin-biotin-alkaline phosphatase method. Immunohistochemical techniques detected most positive samples and produced more clearly visible reactions than did acid-fast staining. Eighteen of 47 samples were positive by immunohistochemical techniques may represent a valuable adjunct to standard techniques for diagnosis of paratuberculosis in goats.     

Improved adherence of genetically modified endothelial cells to small-diameter expanded polytetrafluoroethylene grafts in a canine model

PURPOSE: A significant limitation to using genetically modified endothelial cells (ECs) to seed prosthetic grafts before implantation has been poor cell adherence to the graft lumen. Methodologic changes to improve cell adherence were evaluated in a canine carotid interposition graft model using 4 mm interior diameter expanded polytetrafluoroethylene. METHODS: ECs harvested from external jugular veins were grown in culture, with 80% of the cells from each culture transduced by incubation with an LXSN-type retroviral vector carrying a gene for human prourokinase and a neomycin resistance gene for selection in antibiotic G418. Control grafts had passive luminal coating with fibronectin and were seeded with transduced ECs immediately after G418 selection; these grafts were incubated for 2 days before implantation. Experimental grafts had fibronectin forcefully squeezed through the interstices and were seeded with ECs that had recovered in culture for 5 days after G418 selection; these grafts were incubated for 4 days before implantation. For each control (n = 9) and experimental (n = 12) graft, a graft prepared in the same fashion but seeded with the remaining autologous nontransduced cells was placed in the contralateral carotid artery. Grafts were explanted after 30 days and were evaluated for patency, thrombus-free surface area, and cell-free surface area. RESULTS: No significant differences in patency rates were seen between any groups. The thrombus-free surface area was improved for experimental grafts (90%) compared with control grafts (76%), but this improvement did not achieve statistical significance. The cell-free surface area for transduced cells on experimental grafts was 65% compared with 96% for control grafts (p = 0.021) and was comparable with that for nontransduced cells on both control grafts (62%) and experimental grafts (51%; p = 0.201). CONCLUSIONS: Adherence of genetically modified endothelial cells to small-diameter expanded polytetrafluoroethylene grafts in an in vivo physiologic flow model is significantly improved when cells have a more prolonged recovery from G418 selection, when the graft lumen is more uniformly coated with fibronectin before EC seeding, and when seeded grafts are left longer in culture before implantation to develop cell lining stability. The short-term patency rate of these seeded grafts is not affected by increased cell retention; long-term graft patency data and luminal healing require further evaluation.     

GSOS for probabilistic transition systems: (extended abstract)

We introduce probabilistic GSOS, an operator specification format for (reactive) probabilistic transition systems which arises as an adaptation of the known GSOS format for labelled (nondeterministic) transition systems. Like the standard one, The format is well behaved in the sense that on all models bisimilarity is a congruence and the up-to-context proof principle is valid. Moreover, every specification has a final model which can be shown to offer unique solutions for guarded recursive equations. The format covers operator specifications from the literature, so that the well-behavedness results given for those arise as instances of our general one.The novel format was obtained via the following procedure: Turi and Plotkin have modelled specifications in the (standard) GSOS format and their models as natural transformations of a certain shape and a class of bialgebras identified by them. Several well-behavedness results for the concrete format can elegantly be proved in the categorical setting. Since the abstract framework is parametric in the type of system behaviour under consideration, it can be instantiated with that of probabilistic transition systems yielding a specification format for them, again in terms of specific natural transformations. The main contribution of this paper is the derivation of probabilistic GSOS as a rule-style representation of those.     

Damping behaviour of polymeric materials subjected to longitudinal loads

The present paper reports on measurements of shear modulus and damping in a torsion pendulum on polymeric materials and paper. The experiments were carried out in a torsion device which permitted an axial load to be applied to the sample. At low loads, apparent changes in modulus and damping were recorded. At higher loads, under which marked creep occurred, the damping increased at the moment of loading and then decreased slowly, eventually approaching an equilibrium value. After release of the load, a transient decrease in damping was observed, the damping value of the origin sample being recovered after some time. During the creep and recovery processes, the modulus remained constant.     

The efficiency of CO vibrational excitation in a self-sustained CW glow discharge

The fraction of the electrical power which is placed into the vibrational energy mode of CO by a CW, aerodynamically stabilized, glow discharge has been found to decrease from 76 to 30 percent as the input energy increases from zero to 0.8 eV per CO molecule. The remaining energy is measured as being lost to gas heating within the discharge. In the first of the two experiments reported here, the vibrational energy was transferred into stream heating by collisions of the excited CO molecules with aluminum screening. The resulting heating was used to determine the energy in CO vibration. In the second experiment, the relative intensities of the spontaneous emission from the overtone bands of CO were used to determine the vibrational energy content of the CO. The results of the two measurements agreed well. The fraction of power entering vibration was found to depend on the energy loading per CO molecule, independent of He diluent concentration, total pressure, or nearness to the arcing limit. The maximum energy which can be stored in vibration for this self-sustained discharge was found to be approximately 0.25 eV/CO molecule.