Josephson junctions as self-oscillating mixers at 34 GHz

Adjustable point-contact Josephson junctions have been used as self-oscillating mixers at 34 GHz, with an intermediate frequency of 300 MHz. The average conversion loss was about 18 dB, but mismatch losses and waveguide losses may amount to 10 dB at present.     

The reversible oxidation of aromatic cation radicals to dications. Solvents of low nucleophilicity

Reversible behavior for both electron transfers for oxidation of aromatic compounds to cation radicals and dications was observed in several common electrolytic solvents. Nitriles, nitro compounds and dichloromethane can all be rendered essentially nucleophile free for voltammetric purposes simply by conducting the voltammetric measurements over neutral alumina shortly after the mixture has been stirred. Solvents containing trifluoroacetic acid and the corresponding acid anhydride are not only useful for voltammetry but can also be used to prepare stable solutions of cation radicals and dications. Equilibrium constants for the disproportionation of cation radicals to dications were calculated from the reversible electrode potentials and the effect of changes in the solvent system on the equilibrium constants is discussed.     

An evaluation of procedures used in staging carcinoma of the cervix

A review of 227 cases of invasive carcinoma of the cervix was undertaken to determine the efficacy of procedures using in the staging of this disease. All patients had a pretreatment chest radiography and intravenous pyelogram. 96.5% had pretreatment cystoscopy, 98.6% had pretreatment proctoscopy, and 92% had a pretreatment barium enema. These patients were retrospectively staged on the findings of physical examination only. Each additional procedure was then evaluated by comparison with the initial staging. Cystoscopy and chest film findings each would have changed the clinical stage in fewer than 1% of cases, barium enema in 1.4%, and proctoscopy in 2.2%. No patient had a positive barium enema without a positive proctoscopy, while two patients had positive proctoscopies with negative barium enemas. The overall yield of positive findings by pretreatment intravenous pyelography was 7.3%. Lymphangiography, although inconsistently done, yielded positive findings in all stages. Chest radiographs, intravenous pyelography, proctoscopy, and lymphangiography are recommended as part of the pretreatment workup of patients with carcinoma of the cervix. Routine barium enema is no longer recommended, and cystoscopy is only recommended in patients with clinical stage IIB disease or greater.     

Behavioral consequences of crowding in the deermouse (Peromyscus maniculatus).

Hypothesized that, when the degree of crowding is manipulated by varying group size in cages of equal size, it is probable that crowded animals will engage in more contact than uncrowded animals. Home-cage observation of 24 male and 24 female deer mice indicates that crowded Ss do, in fact, engage in more contact behavior. Both home-cage observation and testing in pairs for pain-elicited aggression reveal that (a) crowded Ss display more agonistic behavior than uncrowded Ss, and (b) agonistic behavior increases with prolonged crowding. Support is obtained for the theory that the effect of crowding derives from contact with conspecifics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Conflicting" motion cues to the visual and vestibular self-motion systems around 0.06 Hz evoke simulator sickness

The basic question this research addressed was, how does simulator sickness vary with simulated motion frequency? Participants were 11 women and 19 men, 20 to 63 years of age. A visual self-motion frequency response curve was determined using a Chattecx posture platform with a VR4 head-mounted display (HMD) or a back-projected dome. That curve and one for vestibular self-motion specify a frequency range in which vestibular and visual motion stimuli could produce conflicting self-motion cues. Using a rotating chair and the HMD, a third experiment supported (p < .01) the hypothesis that conflicting cues at the frequency of maximum "crossover" between the curves (about 0.06 Hz) would be more likely to evoke simulator sickness than would conflicting cues at a higher frequency. Actual or potential applications of this work include a preliminary design guidance curve that indicates the frequency range of simulated motion that is likely to evoke simulator or virtual reality sickness; for simulators intended to operate in this frequency range, appropriate simulator sickness interventions should be considered during the design process.     

Probabilistic symbolic model checking with PRISM: a hybrid approach

In this paper we present efficient symbolic techniques for probabilistic model checking. These have been implemented in PRISM, a tool for the analysis of probabilistic models such as discrete-time Markov chains, continuous-time Markov chains and Markov decision processes using specifications in the probabilistic temporal logics PCTL and CSL. Motivated by the success of model checkers such as SMV which use BDDs (binary decision diagrams), we have developed an implementation of PCTL and CSL model checking based on MTBDDs (multi-terminal BDDs) and BDDs. Existing work in this direction has been hindered by the generally poor performance of MTBDD-based numerical computation, which is often substantially slower than explicit methods using sparse matrices. The focus of this paper is a novel hybrid technique which combines aspects of symbolic and explicit approaches to overcome these performance problems. For typical examples, we achieve a dramatic improvement over the purely symbolic approach. In addition, thanks to the compact model representation using MTBDDs, we can verify systems an order of magnitude larger than with sparse matrices, while almost matching or even beating them for speed.     

Effects of Phosphorus Enrichment and Wave Simulation on Populations of Ulothrix Zonata from Northern Lake Superior

The effects of phosphorus enrichment and wave simulation on new (denuded rocks) and established populations of Ulothrix zonata were examined in specially designed stationary and rocking tanks on a bedrock ledge overlooking the western arm of Lake Superior at Castle Danger, Minnesota. Tanks received constant flow of lake water and were exposed to the same insolation and climatic conditions as the lake for a 10-week period during July, August, and September 1972. A rocking tank and a stationary tank were enriched to maintain an average concentration of 0.16 mg/L PO₄–P. Two remaining tanks, receiving only lake water, served as controls. Each week, algal material was harvested from the tanks and analyzed for chlorophyll a, ash-free dry weight, and abundance of U. zonata and associated non-filamentous periphytic algae. Diatoms comprised, on the average, 95% of the total non-filamentous periphytic algae.The results show that phosphorus enrichment has marked effects on established populations of U. zonata in addition to favoring recolonization of U. zonata on bare rock substrates. Statistical analysis of the data revealed that phosphorus enrichment caused a significant increase in Ulothrix biomass and chlorophyll a in the enriched tanks. Wave simulation caused a significant reduction in total numbers of non-filamentous algae associated with Ulothrix in the rocking tanks.     

Non-Mendelian inheritance of mosquito susceptibility to infection with Brugia malayi and Brugia pahangi

The mode of inheritance of susceptibility or refractoriness of insect vectors to medically important pathogens such as those causing malaria or filariasis is usually believed to follow normal Mendelian laws and to involve a single pair of alleles. In this report, experiments are described that demonstrate another mode of inheritance of mosquito susceptibility to filarial parasites. Crosses were made between susceptibile and refractory species of the Aedes Scutellaris complex, and the hybrid and backcross progeny were tested for susceptibility to infection by Brugia malayi and Brugia pahangi. The data indicate that inheritance follows a non-Mendelian pattern indicative of extrachromosomal factors inherited through the maternal parent.