Extension of Gutenberg-Richter Distribution to Mw -1.3, No Lower Limit in Sight

With twelve years of seismic data from TauTona Gold Mine, South Africa, we show that mining-induced earthquakes follow the Gutenberg-Richter relation with no scale break down to the completeness level of the catalog, at moment magnitude MW −1.3. Events recorded during relatively quiet hours in 2006 indicate that catalog detection limitations, not earthquake source physics, controlled the previously reported minimum magnitude in this mine. Within the Natural Earthquake Laboratory in South African Mines (NELSAM) experiment\u27s dense seismic array, earthquakes that exhibit shear failure at magnitudes as small as MW −3.9 are observed, but we find no evidence that MW −3.9 represents the minimum magnitude. In contrast to previous work, our results imply small nucleation zones and that earthquake processes in the mine can readily be scaled to those in either laboratory experiments or natural faults

The molecular structure of plant gums, with special reference to gums of the genus Khaya

Many trees, of a wide variety of species, respond to injury by exuding yellowish viscous fluids, which harden on exposure to the atmosphere, producing glassy nodules. These are the plant gums (1), which are among the most complex polysaccharides known. In molecular structure, they resemble the mucilages and the bacterial polysaccharides; in fact, there are no general structural differences between the gums and the mucilages(2 -8). The only distinction lies in their mode of origin, since the mucilages are isolated only by the extraction of seeds or other plant material, in which they apparently serve as food stores or as moisture reservoirs. It is therefore necessary, for the purpose of this thesis, to give a restricting definition of plant gums as uronic acid containing polysaccharide exudates. This definition also excludes resinous exudates of terpenoid structure, and non- exuded neutral polysaccharides which are known colloquially as gums, e.g. carob seed gum, which is a galactomannan (9).The origin of the gums is still uncertain. They are commonly, although not exclusively, Produced in hot, dry climates, and healthy trees tend to exude less gum than those in poor condition. For this reason, it has been suggested that they are the result of infection, and a few gums, including chagual (10) and honey locust gums (11), are in fact known to be pathological products. On the other hand, some gums, such as gum tragacanth, are exuded copiously immediately after incision of the bark, and are obviously natural products of the plant's metabolism. It also seems unlikely that gums produced on a commercial basis are the products of infection. In general, it is probable that a tree exudes gum in order to seal off the injured part, and to prevent the spread of infection. The similarity of the gums and the bacterial polysaccharides, and the cross -reactions which can take place between gums and some Pneumococcus sera (12), may be significant in this context, and the complexity of structure of the gum polysaccharides may be connected with the necessity for dealing with a variety of attacking bacteria.The commercial use of gums is almost as old as civilization. The Egyptians used them in embalming, and for the last few hundred years they have been common ingredients of medicines and of 'aids to beauty'. Today, they are still used in the fields of pharmaceuticals and cosmetics, but a wide range of manufacturing processes also employs them as emulsifiers, adhesives, thickeners, binding materials, etc. Being harmless and tasteless, they find many uses in the food industry.In view of their commercial importance, the scientific study of gums is worthwhile, and of course is also important for its intrinsic biochemical interest. But perhaps the most important reason for carrying out investigations lies in the resemblance to bacterial polysaccharides. It may be possible, by drawing analogies, to gain. insight into the structure and formation of the latter, and thus to proceed to a fuller understanding of the bacteria themselves.A typical gum possesses a highly branched structure, containing anything from two to four different neutral sugar residues, and a uronic acid residue; each may exist in more than one type of linkage. Several gums recently investigated are further complicated by the fact that they contain two different uronic acid residues. The most common neutral sugars are D-galactose, D-mannose, L-arabinose, D-xylose and L-rhamnose, but L-fucose and D-tagatose have also been observed. The uronic acids of gums are D- glucuronic acid, 4 -0- methyl-D-glucuronic acid and D-galacturonic acid.In the natural state, many guns exist as neutral salts of such cations as calcium and magnesium. Some, e.g. the Sterculia gums and Cochlosoermum gossypium, are acetylated, and give off a distinct odour of acetic acid. Varying molecular weights have been quoted, ranging from 2 - 300,000 for gum arabic, to 9,500,000 for Karaya gum (13). The usual means of measurement is by sedimentation techniques. Because of the structural complexity of the molecules concerned, chemical methods of molecular weight determination are in general unsatisfactory

ZNF804A genotype modulates neural activity during working memory for faces

Copyright © 2013 S. Karger AG, Basel.Peer reviewedPublisher PD

Broadband Records of Earthquakes in Deep Gold Mines and a Comparison with Results from SAFOD, California

For one week during September 2007, we deployed a temporary network of field recorders and accelerometers at four sites within two deep, seismically active mines. The ground-motion data, recorded at 200 samples/sec, are well suited to determining source and ground-motion parameters for the mining-induced earthquakes within and adjacent to our network. Four earthquakes with magnitudes close to 2 were recorded with high signal/noise at all four sites. Analysis of seismic moments and peak velocities, in conjunction with the results of laboratory stick-slip friction experiments, were used to estimate source processes that are key to understanding source physics and to assessing underground seismic hazard. The maximum displacements on the rupture surfaces can be estimated from the parameter Rv, where v is the peak ground velocity at a given recording site, and R is the hypocentral distance. For each earthquake, the maximum slip and seismic moment can be combined with results from laboratory friction experiments to estimate the maximum slip rate within the rupture zone. Analysis of the four M 2 earthquakes recorded during our deployment and one of special interest recorded by the in-mine seismic network in 2004 revealed maximum slips ranging from 4 to 27 mm and maximum slip rates from 1.1 to 6:3 m=sec. Applying the same analyses to an M 2.1 earthquake within a cluster of repeating earthquakes near the San Andreas Fault Observatory at Depth site, California, yielded similar results for maximum slip and slip rate, 14 mm and 4:0 m=sec

Determination of DiazaCon in Quail Feed and Quail Serum by Ion Pair Reversed-Phase Chromatography

Liquid chromatographic (LC) methods were developed for quantitating the potential avian contraceptive DiazaCon in quail feed and serum. DiazaCon was extracted from ground quail feed with basic n-butyl chloride. The n-butyl chloride extract was evaporated to dryness. The DiazaCon residues were dissolved in an aqueous methanolic ion pairing solution and quantitated by LC at 206 nm. Avian sera was combined with an equal volume of a pH 4 aqueous solution of ion pairing reagent and filtered to remove interfering proteins. DiazaCon was quantitated by LC. Mean recoveries for 500 and 2000 ppm fortified feed were 89.1 and 91.0%, respectively. The mean recovery for sera fortified at 5 levels ranging from 35 to 2000 ppm was 84.9%. Method limits of detection were approximately 14 and 13 ppm for feed and sera, respectively

Theory-based predictors of multiple clinician behaviors in the management of diabetes

Peer reviewedPostprin

Diabetes care provision in UK primary care practices

Background: Although most people with Type 2 diabetes receive their diabetes care in primary care, only a limited amount is known about the quality of diabetes care in this setting. We investigated the provision and receipt of diabetes care delivered in UK primary care. Methods: Postal surveys with all healthcare professionals and a random sample of 100 patients with Type 2 diabetes from 99 UK primary care practices. Results: 326/361 (90.3%) doctors, 163/186 (87.6%) nurses and 3591 patients (41.8%) returned a questionnaire. Clinicians reported giving advice about lifestyle behaviours (e.g. 88% would routinely advise about calorie restriction; 99.6% about increasing exercise) more often than patients reported having received it (43% and 42%) and correlations between clinician and patient report were low. Patients’ reported levels of confidence about managing their diabetes were moderately high; a median (range) of 21% (3% to 39%) of patients reporting being not confident about various areas of diabetes selfmanagement. Conclusions: Primary care practices have organisational structures in place and are, as judged by routine quality indicators, delivering high quality care. There remain evidence-practice gaps in the care provided and in the self confidence that patients have for key aspects of self management and further research is needed to address these issues. Future research should use robust designs and appropriately designed studies to investigate how best to improve this situation

Neural hyperactivation in carriers of the Alzheimer's risk variant on the clusterin gene

Copyright © 2011 Elsevier B.V. All rights reserved.Peer reviewedPostprin

'I would rather die': reasons given by 16-year-olds for not continuing their study of mathematics

Improving participation rates in specialist mathematics after the subject ceases to be compulsory at age 16 is part of government policy in England. This article provides independent and recent support for earlier findings concerning reasons for non- participation, based on free response and closed items in a questionnaire with a sample of over 1500 students in 17 schools, close to the moment of choice. The analysis supports findings that perceived difficulty and lack of confidence are important reasons for students not continuing with mathematics, and that perceived dislike and boredom, and lack of relevance, are also factors. There is a close relationship between reasons for non-participation and predicted grade, and a weaker relation to gender. An analysis of the effects of schools, demonstrates that enjoyment is the main factor differentiating schools with high and low participation indices. Building on discussion of these findings, ways of improving participation are briefly suggested