Interaction between phase-slip centers in superconducting indium microbridges

We have studied the electric behavior of phase-slip centers in superconducting indium microbridges of 0.9 µm thickness, 3–4 µm width, and 70–130 µm length. Our measurements were performed in the temperature range 3–10 mK below the critical temperature T_c resulting in relatively large values (about 10–20 µm) of the quasiparticle diffusion length. The temperature dependent Ginzburg-Landau coherence length (T) has been determined for all samples from the measured temperature dependence of the critical current density. The fabrication of two notches in the indium bridge has been found to localize reliably the nucleation site of the first two phase-slip centers. Our measurements quantitatively confirmed the dc interaction predicted by the model of Kadin, Smith, and Skocpol. In addition, for temperatures very close toT _c , an ac interaction has been observed which disappears abruptly for decreasing temperature. No voltage coupling has been detected.     

Electro-thermal circuit simulation using simulator coupling

The paper presents a methodology for simulating the static and dynamic performance of integrated circuits in the presence of electro-thermal interactions on the integrated circuit die. The technique is based on the coupling of a finite element method (FEM) program with a circuit simulator. In contrast to other known simulator couplings a time step algorithm is used, Its implementation in simulation tools is described. The thermal modeling of the die/package structure and the extended modeling of the electronic circuit is discussed. Simulation results which indicate the capabilities of the methodology for electro-thermal simulation are compared to experimental results     

Failure mechanisms of LWR steel containment buildings subject to severe accident loadings

The potential failure mechanisms in LWR steel containment buildings subject to quasi-static pressurization and elevated temperature are identified. For each failure mechanism, the relevant structural response measures are discussed. For mechanisms involving leakage, the importance of seal performance is also discussed. Criteria that can be used to evaluate threshold environments are presented for several failure mechanisms. Results of tests on scale models and seal tests that support the criteria are referenced.     

Contamination of milk and milk products with chlorinated hydrocarbons in the Westphalian area. II. Results and discussion]

During the time of August 1972 til end of January 1974 samples of butter from 20 dairies from the westfalian area were investigated with regard to their content of chlorinated hydrocarbons. In all samples of milk and butter could be proved: HCB, alpha-, beta-, and gamma-BHC, Heptachlorepoxid (HE), DDT, DDE, DDD, Dieldrin and PCB's, not however, Aldrin, Heptachlor and o,p'-DDT. With HCB, alpha- and gamma-BHC a dependance on the season was observed with maximum values during the winter months. With DDT, DDE and HE the variations were less. With PCB's dependencies on the season or influences of the location were not be recognised. The structure of farming seems to have a significant influence on the contents of HCB. In the course of butter processing the content on chlorinated hydrocarbons related to milk fat is not changed, metabolization does not play a role, either. With the start of lactation the concentration of chlorinated hydrocarbons especially of PCB's are increased as could be shown with single samples.     

Microwave-induced decomposition of nitrogen-rich iron salts and CNT formation from iron(III)-melonate Fe[C9N13]

Two nitrogen-rich iron salts, ferric ferrocyanide (Fe₄[Fe(CN)₆]₃, Prussian Blue, “PB”) and iron melonate (Fe[C₆N₇(NCN)₃], “FeM”), were thermally decomposed. A household microwave oven was used to heat a molybdenum wire after being coated with the precursor and protected from ambient atmosphere. The nanostructured products obtained were characterised with FTIR- and Raman-spectroscopy, XRD, SEM, EDX, EELS and TEM. While the PB-precursor did not give any nanotube-containing products, the FeM-precursor furnished tubular carbon nanostructures in a reproducible manner. This result may be due to the graphite-like nature of the [C₆N₇(NCN)₃]³⁻-anions present in FeM. The C₆N₇-unit is aromatic and completely planar, while the cyanide anions in PB do not provide similar structures. Another significant difference is the high Fe:C-ratio in PB, which might prevent CNT-formation when this precursor is used. The nitrogen content of the tubes was found to be below the detection limit of EELS. This indicates that the synthesis temperatures were too high resulting in complete evaporation of all nitrogen present in the FeM-precursor forming volatile species such as N₂ or (CN)₂.     

Electrogenic cation transport across leech caecal epithelium

This paper is based on the analyses of data collected in the Tanzania Demographic and Health Survey (TDHS). The TDHS national sample was obtained by using 1988 population census list of enumeration areas. Information about sexual behaviour and condom use was obtained from sexually active women (N = 4620) and men (N = 1440) reporting sexual activity during the period of four weeks preceding the survey. Univariate and multivariate (using logistic regression model) analyses were done to identify predictors of condom use and highrisk sexual behaviour. About 6% of women and 31% of men reported to have more than one sexual partner during the study period. Compared to respondents married once and in monogamous union, the tendency to have multiple partners was increased among never married women [OR 10.9, 95% CI (7.1-16.9)] and men [2.6 (1 7-3.9)], formerly married women [11.5 (7.3-17.9)], and among men in monogamous marriage reporting more than one marriage [12.4 (8.3-18.4)]. Occupation, residence, ever use of contraceptives, and AIDS knowledge were not associated with history of multiple sexual partners. Only 134 (9.3%) men and 173 (3.7%) women reported to have used condoms during the study period. After adjusting for other predictors of condom use, respondents reporting multiple sexual partners were more likely to have used condom among both women [3.4 (2.2-5.4)] and men [3.3 (2.3-6.0)]. Condom use was common in urban areas than rural areas and among unmarried respondents. These results show that high-risk sexual behaviour is common among men. Condom use was very low indicating that efforts to promote condom use has been less successful in Tanzania. More efforts are needed to promote safer sexual practices and condom use in Tanzania.