The generation of laser difference frequencies using the scanningtunneling microscope

Infrared laser radiation and radio frequency signals were coupled into the tunneling junction of a scanning tunneling microscope (STM), and the difference frequencies and their harmonics generated in the nonlinear junction were studied as a function of the tunneling parameters. Difference frequencies up to 9 GHz were observed. The importance of the results for the difference frequency mixing in metal-insulator-metal (MIM) diodes and for the STM is discussed. The experiments demonstrate that the tunneling junction of the STM can be used to generate difference frequencies of injected electromagnetic radiation in a similar way and with a similar efficiency to those of the MIM diodes. Due to the precise controllability of the tunneling parameters in the STM the frequency mixing process in its tunneling junction is highly reproducible     

The characteristics of the technical instrumental support for the osteosynthesis of femoral neck fractures using the Seppo fixator

Operative treatment of fractures of the femur neck is the method of choice. The authors prefer the A. Seppo construction out of great number of fixtures but it is difficult to introduce and remove this fixture due to its complexity. To make the procedure of such interventions easier the authors propose a marking device, a screwdriver and a device allowing the fixture's curvature to be regulated. The modification of the technique and using a specially developed extractor is explained by difficulties in removing the fixture by common methods. The variant of the improved instrumental tooling proposed by the authors makes the operation more handy and practicable.     

Artificial language comprehension and size transposition by a California sea lion (Zalophus californianus).

A variation of the conditional discrimination procedure defines relations between stimuli (e.g., gestural signs and their referents) and has been used to study language comprehension in California sea lions. Animals followed instructions given by a trainers' gestures designating properties of size, brightness, and location (adjectives); types of objects (nouns); and actions (verbs). The signs could be combined and recombined according to a conditional sequence or syntax. In the present study, the experimenters sought to determine whether adjectives for size had an absolute meaning (small and large), and a comparative meaning (smaller and larger). A sea lion was given experience with signs designating standards small and large spheres in commands such as large ball mouth. On transposition tests, the small ball was removed and the previously designated large ball was paired with an even larger one. The results show that the adjectives had both an absolute and a relative meaning. Object choices and searching behavior revealed that the S processed information about the relation of size as well as about the specific characteristics of sizes of spheres that instantiated the relations. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of donor-specific hyporesponsiveness following late failure of human renal allografts

Limiting dilution assays to measure the frequency of interleukin-2-secreting peripheral blood T cells were carried out in patients, whose renal allografts had failed due to acute rejection (9 patients) and in patients whose grafts failed more than two years after transplantation without any recent evidence of acute rejection. Using a modified form of the assay we demonstrate that nearly half of 18 patients whose renal transplants had failed after more than two years have low or undetectable HTLp frequencies against donor, but not third-party DR antigens. No such difference was observed in any of the nine patients studied whose transplants were lost from early acute rejection. These results provide the first indication that, as in rodent models of transplantation, T cell unresponsiveness towards donor MHC antigens can occur following prolonged residence of an allograft in humans. Furthermore, the results suggest that chronic rejection may be driven by mechanisms other than direct allorecognition. The assay may be a valuable tool to study the evolution of donor-specific direct T cell alloresponsiveness in patients with well-functioning grafts.