Organic polysulphides in town gas: II. The chemistry of the mercaptan/sulphur reaction

The mechanism of the lime-catalysed reaction between alkyl mercaptans and elemental sulphur has been investigated, and is found to be essentially the same as that of amine-catalysed reactions. From the following and other reported results, the reaction is interpreted in terms of electron delocalisation by pπ-dπ orbital overlap in sulphur chains, leading to predictable, ordered, stepwise nucleophilic degradations of these sulphur chains. The appearance of polysulphides during the dry-purification of town gas (to remove hydrogen sulphide) results from mercaptan/sulphur reactions; the present study indicates that, under conditions existing in dry-purification systems, it is not possible to interfere with these reactions and thus prevent polysulphide formation.     

A low-noise SIS receiver measured from 480 GHz to 650 GHz using Nb junctions with integrated RF tuning circuits

A heterodyne receiver using an SIS waveguide mixer with two mechanical tuners has been characterized from 480 GHz to 650 GHz. The mixer uses either a single 0.5 × 0.5 µm² Nb/AlO_x/Nb SIS tunnel junction or a series array of two 1 µm² Nb tunnel junctions. These junctions have a high current density, in the range 8 – 13 kA/cm². Superconductive RF circuits are employed to tune the junction capacitance. DSB receiver noise temperatures as low as 200 ± 17 K at 540 GHz, 271 K ± 22 K at 572 GHz and 362 ± 33 K at 626 GHz have been obtained with the single SIS junctions. The series arrays gave DSB receiver noise temperatures as low as 328 ± 26 K at 490 GHz and 336 ± 25 K at 545 GHz. A comparison of the performances of series arrays and single junctions is presented. In addition, negative differential resistance has been observed in the DC I–V curve near 490, 545 and 570 GHz. Correlations between the frequencies for minimum noise temperature, negative differential resistance, and tuning circuit resonances are found. A detailed model to calculate the properties of the tuning circuits is discussed, and the junction capacitance as well as the London penetration depth of niobium are determined by fitting the model to the measured circuit resonances.     

Investigator characteristics as moderators of personnel selection research: A meta-analysis.

Surrogate measures of original authors' reward context, primary motivation for doing the research, and knowledge, skills, and abilities (KSAs) were examined for their affect on criterion-related validities reported in the Journal of Applied Psychology and Personnel Psychology between 1964 and 1992. Number of years of experience (a surrogate KSA measure) displayed no moderating relationship. Type of organizational need (equal employment opportunity compliance, augmenting existing selection system, etc.) and investigator interests (e.g., theory testing) were related to criterion-related validities. Place of authors' employment (i.e., reward context) also displayed a moderating relationship (authors in private industry reported higher average validities in comparison with academics). Interaction effects on criterion-related validities were found between authors' experience and (1) place of employment and (2) primary motivation for conducting the research. Results are interpreted in view of possible differences in ability, motivation, and opportunity to do research across employment settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimizing the detection of colorectal liver metastases within the Canadian health care system

BACKGROUND: Five to seven percent of patients with psoriasis suffer additionally from accompanying arthritis. AIM OF THE STUDY: In this article, we review the current knowledge on clinical, diagnostic and therapeutic aspects of the disease. PATIENTS AND RESULTS: Data are presented on the treatment of six patients with the immunosuppressant ciclosporin. Therapeutic results with this drug are superior to agents traditionally used for management of psoriatic arthritis. CONCLUSION: The therapeutic options have been enlarged by the introduction of new immunosuppressive drugs, particularly ciclosporin.     

A load frequency control algorithm based on a generalized approach

A generalized approach to load frequency control that combines discontinuous control and dual-mode control and uses variable-structure-systems concepts is developed. Using this approach, a novel load-frequency control algorithm is proposed. Studies on a multi-area power system, including generation rate constraint and governor dead-band, demonstrate the effectiveness of the control scheme     

Association between cigarette smoking and C-reactive protein in a representative, population-based sample of adolescents.

Although related to inflammatory markers in adults, little is known about the association between cigarette smoking and C-reactive protein (CRP) in adolescent smokers. We examined the association between high-sensitivity CRP (hs-CRP) concentrations and smoking in youth. We used data from a cross-sectional, province-wide survey of a representative sample of youth conducted in Quebec, Canada, in 1999. Data were collected in self-report questionnaires completed by participants and their parents. Participants provided a fasting blood sample, and anthropometric measures were undertaken by trained technicians. The present analysis pertains to 1,501 adolescents aged 13 and 16 years who completed questionnaires and for whom blood samples were available. The independent association between a six-category indicator of smoking status and elevated hs-CRP, defined as a value at least in the 90th percentile of the age- and sex-specific CRP distribution, was assessed in multiple logistic regression analyses controlling for potential confounders. Relative to never-smokers, the odds ratios (95% confidence intervals) for puffers (i.e., never smoked a whole cigarette), those who smoked but not in the past month, light past-month smokers, moderate past-month smokers, and heavy past-month smokers were 1.04 (0.55-1.98), 1.76 (1.06-2.94), 1.39 (0.70-2.76), 2.07 (0.96-4.42), and 2.40 (1.18-4.88), respectively. Our data suggest a positive association between smoking status and elevated CRP in adolescents, and in particular among heavier past-month smokers. Damage related to cigarette smoking may begin soon after tobacco use initiation, reinforcing the preventive message that no level of smoking is safe in youth.     

Managing infrastructure for the next generation

Australia has a high ratio of infrastructure to population, much of it constructed in a peak period after the end of the Second World War.² This infrastructure is aging and becoming due for renewal. However the growth and easy finance conditions that gave rise to its initial development no longer exist and the costs of renewal need to be found in a more difficult economic climate. There is growing anecdotal evidence that some communities may face difficulty in funding renewal of their inherited infrastructure and there is the possibility that the high ratio of infrastructure to population may, in some cases, be unsustainable. Unfortunately, information to test this proposition does not generally exist. While Australian governments, at all levels, are now adopting accrual accounting practices and recording assets in their balance sheets, the attention to asset recording is of recent vintage. This has resulted in the need for large scale asset data capture exercises and large scale investment in information technology, but these are being carried out by individual agencies with little or no co-ordination regionally or across the whole of government. This paper reports a major exception to this pattern: an information management and data gathering project across the whole of Victoria, which has enabled all 78 councils involved to predict the cost and timing of their future infrastructure renewal liabilities (A$23.3 billion) in time to develop corrective planning strategies. By using independent consultants to gather data from every council in the state through a standard survey instrument and presenting the results of the data, after extensive data validation processes, on an aggregate, grouped and single council basis, councils now have the ability to compare themselves with others and with the general state picture. The future renewal challenge is now seen to be a general one, reflective of the times, rather than of individual past management practice, and as such is being tackled with greater vigor. Other States in Australia are now looking to adopt this renewal projection method. This paper also includes reference to the major strategies that are being adopted.     

A model for the presence of polychlorinated biphenyls (PCBs) in the Willamette River Basin (Oregon)

The Willamette River drains a 32,000 km2 basin (Basin) in northwestern Oregon. Owing to their persistence and toxicity, polychlorinated biphenyls (PCBs) in resident fish within the Basin at levels above consumption advisory thresholds are a human and environmental health concern. This concern may trigger a Willamette River Total Maximum Daily Load (TMDL) for PCBs, at which time both their probable sources and the mechanism by which they came to be distributed throughout the Basin will be of considerable regulatory interest. Deposition within the Basin of some portion of global primary (1930-1980) and secondary (post-1980) emissions arriving via long-range advective transport in the atmosphere was posited as an explanation. This proposition was explored with a seasonally responsive, dynamic mass balance watershed-scale model that estimated concentrations of toxicologically relevant congeners (PCB-077, -118, -169) in various environmental media over a 90-year period, assuming advective inflow to the Basin's atmosphere to be the only PCB congener source. Model results suggest that rising air concentrations, and associated advective inflows, from increasing primary emissions between 1930 and 1975 (PCB-118 peak inflow, 1970, approximately equal to 11 kg y(-1)) and declining primary and secondary emissionsthereafter, could have yielded congener concentrations observed in air, soil, and fish between 1993 and 2003. The possibility that observed concentrations may be obtainable entirely with inputs from global legacy sources raises questions as to the efficacy of a TMDL directed primarily at local point or area sources. Better characterization of potential sources, and collection of additional soil and air data combined with more sophisticated modeling, appear to be necessary precursors to any PCB TMDL for the Willamette River.