Introduction of a stabilizing 10 residue {beta}-hairpin in Bacillus subtilis neutral protease

A 10 residue ß-hairpin, which is characteristic ofthermostable Bacillus neutral proteases, was engineered intothe thermolabile neutral protease of Bacillus subtilis. Therecipient enzyme remained fully active after introduction ofthe loop. However, the mutant protein exhibited autocatalyticnicking and a 0.4°C decrease in thermostability. Two additionalpoint mutations designed to improve the interactions betweenthe enzyme surface and the introduced ß-hairpin resultedin reduced nicking and increased thermostability. After theintroduction of both additional mutations in the loopcontainingmutant, nicking was largely prevented and an increase in thermostabilityof 1.1°C was achieved.     

Multiprocessor scheduling with communication delays

This paper adresses certain types of scheduling problems that arise when a parallel computation is to be executed on a multiprocessor. We define a model that allows for communication delays between precedence-related tasks, and propose a classification of various submodels. We also review complexity results and optimization and approximation algorithms that have been presented in the literature.     

Flux-based active filter controller

This paper presents a synchronous frame flux-based control method for a parallel active filter application. The flux-based controller directly implements the inverter switchings in the synchronous reference frame by a hysteresis rule-based carrier-less pulse-width modulation (PWM) strategy to achieve high current bandwidth. This paper addresses the issues and impact on parallel active filtering requirements for utility interface of commonly used harmonic front-ends. The synchronous frame flux-based controller provides additional insights for harmonic current compensation requirements. Simulation results provide the validation of the flux-based active filter controller to meet IEEE Standard 519 recommended harmonic standards for large rated nonlinear loads under balanced and unbalanced supply conditions     

Including sorption to black carbon in modeling bioaccumulation of polycyclic aromatic hydrocarbons: uncertainty analysis and comparison to field data

Model estimations of bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) have been higher than field or laboratory data. This has been explained by strong sorption to black carbon (BC). In this paper, eight previously published bioaccumulation datasets were reinterpreted in terms of additional BC sorption. Biota--Solids Accumulation Factors (BSAFs) of PAHs typically decreased by 1-2 orders of magnitude and were better in line with field data in marine, fresh water, and terrestrial ecosystems. Probabilistic BC-inclusive modeling showed that if BC content is not accurately known, uncertainty in BSAFs is 2-3 orders of magnitude (90 percentile confidence interval) due to uncertainty in the BC sorption term. When BC contents are measured, the deviation between model estimations and field measurements reduces to about a factor of 3. This implies that including routine measurements of BC contents is crucial in improving risk estimations of PAHs.     

Cadmium bioaccumulation factors for terrestrial species: application of the mechanistic bioaccumulation model OMEGA to explain field data

In environmental risk assessment of metals it is often assumed that the biota-to-soil accumulation factor (BSAF) is generic and constant. However, previous studies have shown that cadmium bioaccumulation factors of earthworms and small mammals are inversely related to total soil concentrations. Here, we provide an overview of cadmium accumulation in terrestrial species belonging to different trophic levels, including plants, snails and moles. Internal metal concentrations of these species are less than linearly related to total soil levels, which is in accordance with previously observed trends. The mechanistic bioaccumulation model OMEGA (Optimal Modeling for Ecotoxicological Applications) is used to provide a quantitative explanation of these trends in cadmium accumulation. Our results indicate that the model accurately predicts cadmium accumulation in earthworms, voles and shrews when accounting for geochemical availability of metals and saturable uptake kinetics.     

Lymph node revealing solution: a new method for detection of minute axillary lymph nodes in breast cancer specimens

The staging and prognosis of patients with breast cancer is related to the presence or absence of axillary lymph node involvement. However, in some cases no lymph nodes or too small a number of lymph nodes are revealed by the traditional method of palpating and sectioning the axillary fat. In the present study we demonstrate the usefulness of the lymph node revealing solution (LNRS) in breast cancer. Specimens from 13 patients, in whom <10 lymph nodes were identified in the axilla by the traditional method, were included in the study. After excising the lymph nodes by the traditional method, axillary tissue was immersed in LNRS for 6-12 hours. Additional lymph nodes, which stood out as white chalky nodules, were excised and processed as usual. The LNRS increased the mean number of nodes per case from 6.0+/-2.5 found by the traditional method to 12.54+/-4.61 nodes per case (p < 0.01). The size of the nodes identified by the LNRS was significantly smaller (p < 0.01) than those detected by the traditional method. The LNRS changed the lymph node stage of the disease in four of the studied cases (30%). LNRS seems to be the technique of choice for detection of axillary lymph nodes in cases where the number of detected lymph nodes by the traditional method is too small for accurate staging.     

Detecting short periods of elevated workload: A comparison of nine workload assessment techniques.

The present experiment tested the merits of 9 common workload assessment techniques with relatively short periods of workload in a car-driving task. Twelve participants drove an instrumented car and performed a visually loading task and a mentally loading task for 10, 30, and 60 s. The results show that 10-s periods of visual and mental workload can be measured successfully with subjective ratings and secondary task performance. With respect to longer loading periods (30 and 60 s), steering frequency was found to be sensitive to visual workload, and skin conductance response (SCR) was sensitive to mental workload. The results lead to preliminary guidelines that will help applied researchers to determine which techniques are best suited for assessing visual and mental workload. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Presence of Bacillus species in pasteurised milk and their phenotypic and genotypic antimicrobial resistance profile

High-temperature short-time (HTST) pasteurisation is not sufficient for complete elimination of Bacillus sp. in milk. Hence, it is important to assess their prevalence, phenotypic and genetic antimicrobial resistance profiles in pasteurised milk. In this study, we investigated Bacillus prevalence and their phenotypic resistance to 25 antimicrobials and prevalence of five plasmid antimicrobial resistance genes. All isolates were resistant to β-lactams; most isolates were susceptible to chloramphenicol (n = 52), ciprofloxacin, meropenem, sulphonamides, tetracycline and vancomycin (n = 56). Intriguingly, despite phenotypic sulphonamide and tetracycline sensitivity, Sul2 and tetA genes were detected in different Bacillus species, signifying a potential risk of horizontal gene transfer of these mobile resistance genes through pasteurised milk.     

Modeling decreased food chain accumulation of PAHs due to strong sorption to carbonaceous materials and metabolic transformation

The predictive power of bioaccumulation models may be limited when they do not accountfor strong sorption of organic contaminants to carbonaceous materials (CM) such as black carbon, and when they do not include metabolic transformation. We tested a food web accumulation model, including sorption to CM, on data from a model ecosystem experiment with historically contaminated sediment. In combination with measured CM contents of the sediment, the model gave good fits for the biota that are known not to metabolize PAHs (macrophytes, periphyton, floating algal biomass). The same model was applied to invertebrates and fish but now with optimization of their metabolic transformation rates (k(m)). For fish, these rates correlated empirically with log K(OW): Log k(m) = -0.8 log K(OW) + 4.5 (r2 adj = 0.73). For invertebrates, log k(m) did not correlate with logK(OW). Sensitivity analysis revealed that the model output is highly sensitive to sediment CM content and sorption parameters, moderately sensitive to metabolic transformation rates, and slightly sensitive to lipid fraction of the organism and diet-related parameters. It is concluded that CM-inclusive models yield a better assessment of accumulation than models without sorption to CM. Furthermore, inclusion of CM in a model enables metabolic transformation rates to be calculated from the remaining overestimation in the model results when compared to measured data.