The denatured state of N-PGK is compact and predominantly disordered

The Organisation of the structure present in the chemically denatured N-terminal domain of phosphoglycerate kinase (N-PGK) has been determined by paramagnetic relaxation enhancements (PREs) to define the conformational landscape accessible to the domain. Below 2.0 M guanidine hydrochloride (GuHCl), a species of N-PGK (denoted I-b) is detected, distinct from those previously characterised by kinetic experiments [folded (F), kinetic intermediate (I-k) and denatured (D)]. The transition to I-b is never completed at equilibrium, because F predominates below 1.0 M GuHCl. Therefore, the ability of PREs to report on transient or low population species has been exploited to characterise I-b. Five single cysteine variants of N-PGK were labelled with the nitroxide electron spin-label MTSL [(1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-methyl)methanesulfonate] and the denaturant dependences of the relaxation properties of the amide NMR signals between 1.2 and 3.6 M GuHCl were determined. Significant PREs for I-b were obtained, but these were distributed almost uniformly throughout the sequence. Furthermore, the PREs indicate that no specific short tertiary contacts persist. The data indicate a collapsed state with no coherent three-dimensional structure, but with a restricted radius beyond which the protein chain rarely reaches. The NMR characteristics Of I-b indicate that it forms from the fully denatured state within 100 mu s, and therefore a rapid collapse is the initial stage of folding of N-PGK from its chemically denatured state. By extrapolation, I-b is the predominant form of the denatured state under native conditions, and the non-specifically collapsed structure implies that many non-native contacts and chain reversals form early in protein folding and must be broken prior to attaining the native state topology. (C) 2008 Elsevier Ltd. All rights reserved

Vulnerability of Selected Soils in the Different Rainfall Areas to Degradation and Excessive Leaching after Winery Wastewater Application

A pot trial was conducted to assess the effect of simulated rainfall on six soils with different textures, irrigated with winery wastewater diluted to a chemical oxygen demand (COD) level of 3000 mg/L over one simulated irrigation season. Thereafter, simulated winter rainfall was applied to the pots. The rainfall was simulated according to the long term averages of the regions where the soils originated. Leaching of cations, particularly K+ and Na+ occurred only from four of the six soils when winter rainfall was simulated.  In one of the sandy soils, the simulated rainfall was too low to allow leaching. In another soil, high clay content of 35% in combination with low rainfall prevented leaching. In three soils that received the sameamount of rainfall, more cations leached from the duplex sandy soil compared to the two other soils. These trends indicated that leaching of cations was a function of soil texture and rainfall. The study showedthat in regions with low rainfall, irrigation with winery wastewater would lead to the accumulation of cations thereby increasing soil salinity. The study confirmed that for sustainable use of winery wastewaterirrigation in agriculture, different soil types will require individual management in order to avoid or minimize the negative environmental impact on natural resources by wastewater irrigation

Response of Soil Chemical Properties to Irrigation with Winery Wastewater on a Well-drained Sandy Soil

Most wineries in South Africa dispose of their wastewater through land application. This is carried out by irrigating small areas of cultivated pasture with the wastewater or ponding, with the former being the more general practice. Land application of winery wastewater results in the accumulation of potassium (K+) andsodium (Na+) in the soil and leaching of calcium (Ca2+) and magnesium  (Mg2+).This could lead to long term instability of soil structure. The objective of this study was to investigate the effect of irrigation with winery wastewater on chemical soil properties and potential environmental impacts. Therefore, an existinggrazing paddock at a winery near Rawsonville was selected where wastewater had been applied for many years. Due to the high volumes of wastewater irrigation plus rainfall, the inevitable over-irrigation leached large amounts of cations, particular K+ and Na+, beyond 90 cm soil depth at the selected study site. These leached elements are likely to end up in natural water resources in the long run. Irrigation with winery wastewater did not have a pronounced effect on soil pH(KCl). This was probably due to the decomposition of organic matter, and the fact that the applied salts were leached beyond 90 cm depth. The study confirmed that disposal of winery wastewater through land application can only be recommended where wastewaterapplication will not exceed the water requirement of the crop as well as the water holding capacity of the soil which is being irrigated

A qualitative examination of the experience of skin camouflage by people living with visible skin conditions

Background People with a visible skin conditions can experience anxiety and intrusive reactions from others when in social situations. The use of products to conceal marks on the skin is provided in a number of different hospital services and by charities. However, little is known about the experience of people using camouflage as a tool for enhancing quality of life. Aim This study aimed to examine the experience of using skin camouflage to cover a visible mark on the skin. It sought to gain a detailed account of the issues associated with camouflage use and the needs of people using it. Methods Interpretative Phenomenological Analysis (IPA) was used to gain a detailed understanding of the meaning of camouflage use for participants. Six skin camouflage service‐users completed semi‐structured interviews. Results The IPA analysis revealed that the experience of using camouflage was influenced by socio‐cultural factors and the views of others. The use of camouflage was linked to investment in appearance maintenance and functioned to give a sense of control over social interactions, increase social confidence and manage concern about the responses of others. Conclusions This study provides an in‐depth insight into the experience of using skin camouflage and suggests that camouflage can play a valuable role in maintaining wellbeing in those living with a visible skin condition

Effect of Irrigation with Diluted Winery Wastewater on Cations and pH in Four Differently Textured Soils

Environmental legislation requires the South African wine industry to find solutions for winery wastewatertreatment or reuse. The feasibility of irrigation with diluted winery wastewater was assessed in a potexperiment under a rain shelter over four simulated irrigation seasons. Four soils varying in clay contentwere irrigated with winery wastewater diluted to 3 000 mg/L chemical oxygen demand (COD), whereas thecontrol received municipal water. The rate of K+ increase in the soil containing 20% clay was higher thanin soils containing 13% clay or less. This suggests that heavy soils will aggravate the risk of high K+ levels.The risk of Na+ accumulation increased linearly with clay content. Low Ca2+ and Mg2+ concentrations inthe diluted wastewater had no effect on the soil, irrespective of clay content. Irrigation with diluted winerywastewater increased soil pH(KCl) substantially in all the soils over the four simulated seasons. The soil pHincrease was attributed to the addition of organic/bicarbonate salts to the soil. It must be noted that theresults represent a worst case scenario, i.e. in the absence of rainfall or crops

Annual Dynamics of Winery Wastewater Volumes and Quality and the Impact of Disposal on Poorly Drained Duplex Soils

The composition and volume of winery wastewater change throughout the year. Quality is usually at its worst when vintage operations are dominated by the production of red wines. The objective of this study was to investigate the annual dynamics of winery wastewater volumes and quality, as well as the effect of winery wastewater irrigation on the chemical soil properties of a poorly drained duplex soil. The study was conducted over two and half years. The wastewater contained a high concentration of potassium (K+) and low levels of sodium (Na+). The results of the study confirmed that winery wastewater did not complywith South African national legislation for wastewater irrigation with regard to chemical oxygen demand (COD) and pH throughout the study period, while some prominent spikes were observed in sodium adsorption ratio (SAR) and electrical conductivity (EC). Land application of winery wastewater resulted in the accumulation of high levels of K+ in the soil. It is important to note that this study represents the worst-case scenario, i.e. large amounts of wastewater were disposed of on a small surface, particularly during harvest and in winter. Due to the high volumes of wastewater irrigation plus rainfall, the inevitable over-irrigation leached large amounts of K+ beyond 90 cm soil depth. Unfortunately, the leached elements are bound to end up in natural water resources, resulting in the pollution of the environment

Effect of Irrigation with Diluted Winery Wastewater on Phosphorus in Four Differently Textured Soils

The wine industry needs solutions for wastewater treatment, as environmental legislation for its disposal isincreasingly being enforced due to non-compliance. The feasibility of re-using diluted winery wastewaterwas assessed in a pot experiment under a rain shelter over four simulated irrigation seasons. Four soilsvarying in parent material and clay content, viz. aeolic sand from Lutzville containing 0.4% clay, alluvialsand from Rawsonville containing 3.3% clay, granite-derived soil from Stellenbosch containing 13% clay,and shale-derived soil from Stellenbosch containing 20% clay, were irrigated with wastewater diluted to3 000 mg/L COD (chemical oxygen demand), whereas the control received municipal water. Irrigation withdiluted winery wastewater increased the pH(KCl) in the shale- and granite-derived soils into the optimumrange for P availability. Although pH(KCl) in the aeolic sand was initially above the optimum range, relativelyhigh Na+ levels also caused available P to increase as the pH(KCl) increased. The pH(KCl) in the alluvial sandincreased beyond the optimum range, thereby causing a reduction in the available P. This indicates thatirrigation with diluted winery wastewater may only enhance P absorption if the pH(KCl) shift is towards theoptimum. It must be noted that the results represent a worst-case scenario, i.e. in the absence of rainfallor crops

Wing shape as a potential discriminator of morphologically similar pest taxa within theBactrocera dorsalis species complex (Diptera: Tephritidae)

Four morphologically cryptic species of the Bactrocera dorsalis fruit fly complex (B. dorsalis s.s., B. papayae, B. carambolae and B. philippinensis) are serious agricultural pests. As they are difficult to diagnose using traditional taxonomic techniques, we examined the potential for geometric morphometric analysis of wing size and shape to discriminate between them. Fifteen wing landmarks generated size and shape data for 245 specimens for subsequent comparisons among three geographically distinct samples of each species. Intraspecific wing size was significantly different within samples of B. carambolae and B. dorsalis s.s. but not within samples of B. papayae or B. philippinensis. Although B. papayae had the smallest wings (average centroid size=6.002 mm±0.061 SE) and B. dorsalis s.s. the largest (6.349 mm±0.066 SE), interspecific wing size comparisons were generally non-informative and incapable of discriminating species. Contrary to the wing size data, canonical variate analysis based on wing shape data discriminated all species with a relatively high degree of accuracy; individuals were correctly reassigned to their respective species on average 93.27% of the time. A single sample group of B. carambolae from locality ‘TN Malaysia’ was the only sample to be considerably different from its conspecific groups with regards to both wing size and wing shape. This sample was subsequently deemed to have been originally misidentified and likely represents an undescribed species. We demonstrate that geometric morphometric techniques analysing wing shape represent a promising approach for discriminating between morphologically cryptic taxa of the B. dorsalis species complex

SMT-based Model Checking for Recursive Programs

We present an SMT-based symbolic model checking algorithm for safety verification of recursive programs. The algorithm is modular and analyzes procedures individually. Unlike other SMT-based approaches, it maintains both "over-" and "under-approximations" of procedure summaries. Under-approximations are used to analyze procedure calls without inlining. Over-approximations are used to block infeasible counterexamples and detect convergence to a proof. We show that for programs and properties over a decidable theory, the algorithm is guaranteed to find a counterexample, if one exists. However, efficiency depends on an oracle for quantifier elimination (QE). For Boolean Programs, the algorithm is a polynomial decision procedure, matching the worst-case bounds of the best BDD-based algorithms. For Linear Arithmetic (integers and rationals), we give an efficient instantiation of the algorithm by applying QE "lazily". We use existing interpolation techniques to over-approximate QE and introduce "Model Based Projection" to under-approximate QE. Empirical evaluation on SV-COMP benchmarks shows that our algorithm improves significantly on the state-of-the-art.Comment: originally published as part of the proceedings of CAV 2014; fixed typos, better wording at some place

Magnetic fields and Sunyaev-Zel'dovich effect in galaxy clusters

In this work we study the contribution of magnetic fields to the Sunyaev Zeldovich (SZ) effect in the intracluster medium. In particular we calculate the SZ angular power spectrum and the central temperature decrement. The effect of magnetic fields is included in the hydrostatic equilibrium equation by splitting the Lorentz force into two terms one being the force due to magnetic pressure which acts outwards and the other being magnetic tension which acts inwards. A perturbative approach is adopted to solve for the gas density profile for weak magnetic fields (< 4 micro G}). This leads to an enhancement of the gas density in the central regions for nearly radial magnetic field configurations. Previous works had considered the force due to magnetic pressure alone which is the case only for a special set of field configurations. However, we see that there exists possible sets of configurations of ICM magnetic fields where the force due to magnetic tension will dominate. Subsequently, this effect is extrapolated for typical field strengths (~ 10 micro G) and scaling arguments are used to estimate the angular power due to secondary anisotropies at cluster scales. In particular we find that it is possible to explain the excess power reported by CMB experiments like CBI, BIMA, ACBAR at l > 2000 with sigma_8 ~ 0.8 (WMAP 5 year data) for typical cluster magnetic fields. In addition we also see that the magnetic field effect on the SZ temperature decrement is more pronounced for low mass clusters ( ~ 2 keV). Future SZ detections of low mass clusters at few arc second resolution will be able to probe this effect more precisely. Thus, it will be instructive to explore the implications of this model in greater detail in future works.Comment: 20 pages, 8 figure