Consolidation and aggregate densification during gravity thickening

A continuous laboratory column system has been used to investigate the consolidation behaviour of kaolin slurries flocculated by a nonionic flocculant under different conditions. Measurements of the steady-state bed density profile showed that higher agitation intensities during flocculation resulted in lower bed densities. The relative importance of compression versus shear for kaolin dewatering was determined by operating the steady-state column system at different bed heights above a mechanical rake. It was found that rake action, not compression, was the dominant dewatering mechanism. Samples taken from the consolidating bed before and after the rake were analysed by microscopy to determine the density–size relationship of the individual aggregates. This showed that the dewatering induced by the rake action occurred not only by removal of inter-aggregate liquor but also by densification of the aggregates (i.e. removal of intra-aggregate liquor). Measurements made on full-scale thickeners are also presented which demonstrate similar behaviour.     

Cloning, characterisation and expression of the alpha-tubulin genes of the leech, Hirudo medicinalis

BACKGROUND: Exercise testing has long been employed in patients with hypertrophic cardiomyopathy (HCM), although concerns have constantly been expressed regarding its safety. This study reviews a large number of exercise tests performed in a community-based population with HCM, in terms of safety and clinical utility. METHODS: We analyzed a total of 243 maximal symptom-limited cycloergometer exercise tests performed at our institution in 138 patients with HCM (age 42 +/- 14 years, M/F 99/39), who were followed systematically for 9.4 +/- 6.5 years. RESULTS: In none of the 243 exercise tests did cardiac arrest, hemodynamic collapse or malignant arrhythmia occur, although 53 of the study patients (38%) had > or = 1 risk factors including previous cardiac arrest, recurrent syncope, malignant family history and resting left ventricular outflow obstruction. Early termination of the test was necessary in only 8 patients due to symptomatic hypotension with dizziness, but none had syncope. Mean predicted functional capacity achieved by the study group was 77 +/- 22%. Poor performance (< 60% of predicted functional capacity) was observed in 32 patients (23%), and it was associated with a NYHA functional class > 1 and an abnormal blood pressure response to exercise. Non-malignant arrhythmias occurred in 41 patients (30%), including multiple premature ventricular beats (PVB), paroxysmal atrial fibrillation, non-sustained ventricular (NSVT) and supraventricular tachycardia. The combined presence of multiple exercise-induced PVB and NSVT on Holter ECG had a 14% positive but a 97% negative predictive value for sudden death or cardiac arrest. CONCLUSIONS: 1) Exercise testing is safe in a community-based population of patients with HCM, and provides useful information regarding functional capacity, efficacy of treatment, blood pressure response to exercise and inducible ischemia. Thus, ergometry should routinely be included in the standard evaluation and follow-up protocols of HCM patients. 2) Conversely, the utility of ergometry in the evaluation of the arrhythmic risk in HCM patients appears to be limited to the identification of low-risk patients.     

The extent of influence: An alternative approach to identifying dominant contributors to a discipline’s literature

Most studies of scholarly influence within disciplines using citation data do not investigate the extent of an individual’s influence; does it extend over a number of years with a sequence of publications or is it confined to a short period and a small number of publications? Using bibliographic data from a series of quadrennial reports into developments in UK geography, this paper finds that few authors are cited on more than one occasion.     

Binding of the glucose-dependent Mig1p repressor to the GAL1 and GAL4 promoters in vivo: regulationby glucose and chromatin structure

Binding of the MIG1 repressor to the glucose-repressible GAL1 and GAL4 promoters was analyzed in vivo by cyclobutane dimer footprinting in two yeast strains that show different glucose repression responses. Mig1p binding to the two promoters in both strains was glucose-induced. In cells subject to rapid and stringent glucose repression (S288c), long-term Mig1p binding in glucose-grown cells was inhibited by the formation of a competing chromatin structure. Under conditions where glucose repression was only partially effective (gal80 - or low glucose), the chromatin structure did not form and long-term Mig1p binding was observed The same long-term binding of Mig1p was seen in cells of a different strain (W303A) that shows only partial glucose repression of the GAL1 promoter. We conclude from these experiments that Mig1p binding to glucose-repressed promoters is glucose-dependent but transient. We suggest that Mig1p functions at an early step in repression, but is not required to maintain the repressed state.     

二氧化碳包水的微乳液可做为包括蛋白质的亲水物的溶体（英）

全氟聚醚碳酸铵表面活性剂用在超临界ＣＯ２之中形成微乳液，使非挥发的亲水蛋白质可以溶解在这种ＣＯ２流体之中。用四种光谱技术证实了这种微乳液滴的特性与水的特性相近，并为合成具有该牧场生的表面活性剂提出模式。     

USING A NON‐PHYSICAL BEHAVIOURAL BARRIER TO ALTER MIGRATION ROUTING OF JUVENILE CHINOOK SALMON IN THE SACRAMENTO–SAN JOAQUIN RIVER DELTA

Anthropogenic alterations to river systems, such as irrigation and hydroelectric development, can negatively affect fish populations by reducing survival when fish are routed through potentially dangerous locations. Non‐physical barriers using behavioural stimuli are one means of guiding fish away from such locations without obstructing water flow. In the Sacramento–San Joaquin River Delta, we evaluated a bio‐acoustic fish fence (BAFF) composed of strobe lights, sound and a bubble curtain, which was intended to divert juvenile Chinook salmon (Oncorhynchus tshawytscha) away from Georgiana Slough, a low‐survival migration route that branches off the Sacramento River. To quantify fish response to the BAFF, we estimated individual entrainment probabilities from two‐dimensional movement paths of juvenile salmon implanted with acoustic transmitters. Overall, 7.7% of the fish were entrained into Georgiana Slough when the BAFF was on, and 22.3% were entrained when the BAFF was off, but a number of other factors influenced the performance of the BAFF. The effectiveness of the BAFF declined with increasing river discharge, likely because increased water velocities reduced the ability of fish to avoid being swept across the BAFF into Georgiana Slough. The BAFF reduced entrainment probability by up to 40 percentage points near the critical streakline, which defined the streamwise division of flow vectors entering each channel. However, the effect of the BAFF declined moving in either direction away from the critical streakline. Our study shows how fish behaviour and the environment interacted to influence the performance of a non‐physical behavioural barrier in an applied setting. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

Synthesis of vinyloxy phosphorus monomers from the enolate of acetaldehyde

Summary A simple synthetic procedure for vinyloxy phosphorus monomers involves the reaction of the enolate of acetaldehyde, obtained from the cycloreversion of tetrahydrofuran in the presence of n-butyllithium, with chlorophosphites or phosphorochloridates leading to vinyl phosphites or vinyl phosphates, respectively, in high yield and purity. Received: 17 August 2000/Accepted: 8 September 2000     

Near-field scanning optical microscopy probes: a comparison of pulled and double-etched bent NSOM probes for fluorescence imaging of biological samples

Bent near‐field optical probes for biological applications have been fabricated using a combination of a two‐step chemical etching method and focused ion beam milling to create a well‐defined aperture. The transmission efficiencies have been evaluated as a function of laser wavelength (λ) and aperture size (D) for both large and small core fibres. The probe transmission behaviour follows a (D/λ)³ relationship. The double‐etched probes are compared to pulled probes fabricated from highly GeO₂‐doped dispersion compensating fibre and a standard single‐mode optical fibre. The transmission efficiencies of both types of pulled probes are approximately two orders of magnitude lower than double‐etched probes with similar aperture sizes. To demonstrate the utility of the various probes, their imaging performance has been evaluated for samples of polymer beads and phase‐separated phospholipid monolayers of dipalmitoylphosphatidylcholine or cholesterol/phosphatidylcholine/sphingomyelin mixtures. Both pulled and double‐etched probes are suitable for fluorescence imaging of polymer spheres. However, pulled probes are rapidly damaged at the higher input laser intensities required for fluorescence imaging of monolayer samples doped with < 1% of a fluorescent dye‐labelled lipid. The images obtained with the double‐etched probes show excellent spatial resolution and signal/noise, illustrating the potential of such probes for imaging of biological samples.