Modeling Eddy Current Crack Signals of Differential and Reflection Probes

The efforts of past several years have resulted in development of an eddy current model [1–8], using the boundary element method (BEM). As of last year, the BEM algorithm based on the Hertz potential approach [1–3] was shown to be effective in dealing with complex part and probe geometry [4–6], and particularly in modeling crack signals [7–9]. Previously, the modeling capabilities were demonstrated mostly with absolute probes. This year, the focus has been shifted toward on crack signals of differential and reflection probes

Influence of hyperhomocysteinemia on the cellular redox state - Impact on homocysteine-induced endothelial dysfunction

Hyperhomocysteinemia is an independent risk factor for the development of atherosclerosis. An increasing body of evidence has implicated oxidative stress as being contributory to homocysteines deleterious effects on the vasculature. Elevated levels of homocysteine may lead to increased generation of superoxide by a biochemical mechanism involving nitric oxide synthase, and, to a lesser extent, by an increase in the chemical oxidation of homocysteine and other aminothiols in the circulation. The resultant increase in superoxide levels is further amplified by homocysteinedependent alterations in the function of cellular antioxidant enzymes such as cellular glutathione peroxidase or extracellular superoxide dismutase. One direct clinical consequence of elevated vascular superoxide levels is the inactivation of the vasorelaxant messenger nitric oxide, leading to endothelial dysfunction. Scavenging of superoxide anion by either superoxide dismutase or 4,5-dihydroxybenzene 1,3-disulfonate (Tiron) reverses endothelial dysfunction in hyperhomocysteinemic animal models and in isolated aortic rings incubated with homocysteine. Similarly, homocysteineinduced endothelial dysfunction is also reversed by increasing the concentration of the endogenous antioxidant glutathione or overexpressing cellular glutathione peroxidase in animal models of mild hyperhomocysteinemia. Taken together, these findings strongly suggest that the adverse vascular effects of homocysteine are at least partly mediated by oxidative inactivation of nitric oxide

Age-related differences in adaptation during childhood: The influences of muscular power production and segmental energy flow caused by muscles

Acquisition of skillfulness is not only characterized by a task-appropriate application of muscular forces but also by the ability to adapt performance to changing task demands. Previous research suggests that there is a different developmental schedule for adaptation at the kinematic compared to the neuro-muscular level. The purpose of this study was to determine how age-related differences in neuro-muscular organization affect the mechanical construction of pedaling at different levels of the task. By quantifying the flow of segmental energy caused by muscles, we determined the muscular synergies that construct the movement outcome across movement speeds. Younger children (5-7 years; n = 11), older children (8-10 years; n = 8), and adults (22-31 years; n = 8) rode a stationary ergometer at five discrete cadences (60, 75, 90, 105, and 120 rpm) at 10% of their individually predicted peak power output. Using a forward dynamics simulation, we determined the muscular contributions to crank power, as well as muscular power delivered to the crank directly and indirectly (through energy absorption and transfer) during the downstroke and the upstroke of the crank cycle. We found significant age × cadence interactions for (1) peak muscular power at the hip joint [Wilks' Lambda = 0.441, F(8,42) = 2.65, p = 0.019] indicating that at high movement speeds children produced less peak power at the hip than adults, (2) muscular power delivered to the crank during the downstroke and the upstroke of the crank cycle [Wilks' Lambda = 0.399, F(8,42) = 3.07, p = 0.009] indicating that children delivered a greater proportion of the power to the crank during the upstroke when compared to adults, (3) hip power contribution to limb power [Wilks' Lambda = 0.454, F(8,42) = 2.54, p = 0.023] indicating a cadence-dependence of age-related differences in the muscular synergy between hip extensors and plantarflexors. The results demonstrate that in spite of a successful performance, children construct the task of pedaling differently when compared to adults, especially when they are pushed to their performance limits. The weaker synergy between hip extensors and plantarflexors suggests that a lack of inter-muscular coordination, rather than muscular power production per se, is a factor that limits children's performance ranges

A statistical toolbox for metagenomics: assessing functional diversity in microbial communities

<p>Abstract</p> <p>Background</p> <p>The 99% of bacteria in the environment that are recalcitrant to culturing have spurred the development of metagenomics, a culture-independent approach to sample and characterize microbial genomes. Massive datasets of metagenomic sequences have been accumulated, but analysis of these sequences has focused primarily on the descriptive comparison of the relative abundance of proteins that belong to specific functional categories. More robust statistical methods are needed to make inferences from metagenomic data. In this study, we developed and applied a suite of tools to describe and compare the richness, membership, and structure of microbial communities using peptide fragment sequences extracted from metagenomic sequence data.</p> <p>Results</p> <p>Application of these tools to acid mine drainage, soil, and whale fall metagenomic sequence collections revealed groups of peptide fragments with a relatively high abundance and no known function. When combined with analysis of 16S rRNA gene fragments from the same communities these tools enabled us to demonstrate that although there was no overlap in the types of 16S rRNA gene sequence observed, there was a core collection of operational protein families that was shared among the three environments.</p> <p>Conclusion</p> <p>The results of comparisons between the three habitats were surprising considering the relatively low overlap of membership and the distinctively different characteristics of the three habitats. These tools will facilitate the use of metagenomics to pursue statistically sound genome-based ecological analyses.</p

Culture-Independent Microbiological Analysis of Foley Urinary Catheter Biofilms

Background: Prevention of catheter-associated urinary tract infection (CAUTI), a leading cause of nosocomial disease, is complicated by the propensity of bacteria to form biofilms on indwelling medical devices [1,2,3,4,5]. Methodology/Principal Findings: To better understand the microbial diversity of these communities, we report the results of a culture-independent bacterial survey of Foley urinary catheters obtained from patients following total prostatectomy. Two patient subsets were analyzed, based on treatment or no treatment with systemic fluoroquinolone antibiotics during convalescence. Results indicate the presence of diverse polymicrobial assemblages that were most commonly observed in patients who did not receive systemic antibiotics. The communities typically contained both Gram-positive and Gramnegative microorganisms that included multiple potential pathogens. Conclusion/Significance: Prevention and treatment of CAUTI must take into consideration the possible polymicrobial nature of any particular infection

Substrate reduction therapy for Krabbe disease and metachromatic leukodystrophy using a novel ceramide galactosyltransferase inhibitor

Krabbe disease (KD) and metachromatic leukodystrophy (MLD) are caused by accumulation of the glycolipids galactosylceramide (GalCer) and sulfatide and their toxic metabolites psychosine and lysosulfatide, respectively. We discovered a potent and selective small molecule inhibitor (S202) of ceramide galactosyltransferase (CGT), the key enzyme for GalCer biosynthesis, and characterized its use as substrate reduction therapy (SRT). Treating a KD mouse model with S202 dose-dependently reduced GalCer and psychosine in the central (CNS) and peripheral (PNS) nervous systems and significantly increased lifespan. Similarly, treating an MLD mouse model decreased sulfatides and lysosulfatide levels. Interestingly, lower doses of S202 partially inhibited CGT and selectively reduced synthesis of non-hydroxylated forms of GalCer and sulfatide, which appear to be the primary source of psychosine and lysosulfatide. Higher doses of S202 more completely inhibited CGT and reduced the levels of both non-hydroxylated and hydroxylated forms of GalCer and sulfatide. Despite the significant benefits observed in murine models of KD and MLD, chronic CGT inhibition negatively impacted both the CNS and PNS of wild-type mice. Therefore, further studies are necessary to elucidate the full therapeutic potential of CGT inhibition

Three-Dimensional X-ray Observation of Atmospheric Biological Samples by Linear-Array Scanning-Electron Generation X-ray Microscope System

Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD) array. The specimens are placed under a CuZn-coated Si3N4 thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields

Wall roughness induces asymptotic ultimate turbulence

Turbulence is omnipresent in Nature and technology, governing the transport of heat, mass, and momentum on multiple scales. For real-world applications of wall-bounded turbulence, the underlying surfaces are virtually always rough; yet characterizing and understanding the effects of wall roughness for turbulence remains a challenge, especially for rotating and thermally driven turbulence. By combining extensive experiments and numerical simulations, here, taking as example the paradigmatic Taylor-Couette system (the closed flow between two independently rotating coaxial cylinders), we show how wall roughness greatly enhances the overall transport properties and the corresponding scaling exponents. If only one of the walls is rough, we reveal that the bulk velocity is slaved to the rough side, due to the much stronger coupling to that wall by the detaching flow structures. If both walls are rough, the viscosity dependence is thoroughly eliminated in the boundary layers and we thus achieve asymptotic ultimate turbulence, i.e. the upper limit of transport, whose existence had been predicted by Robert Kraichnan in 1962 (Phys. Fluids {\bf 5}, 1374 (1962)) and in which the scalings laws can be extrapolated to arbitrarily large Reynolds numbers

Arrhythmogenic right ventricular cardiomyopathy mimics: role of cardiovascular magnetic resonance.

BACKGROUND: Cardiovascular magnetic resonance (CMR) is commonly used in patients with suspected arrhythmogenic right ventricular cardiomyopathy (ARVC) based on ECG, echocardiogram and Holter. However, various diseases may present with clinical characteristics resembling ARVC causing diagnostic dilemmas. The aim of this study was to explore the role of CMR in the differential diagnosis of patients with suspected ARVC. METHODS: 657 CMR referrals suspicious for ARVC in a single tertiary referral centre were analysed. Standardized CMR imaging protocols for ARVC were performed. Potential ARVC mimics were grouped into: 1) displacement of the heart, 2) right ventricular overload, and 3) non ARVC-like cardiac scarring. For each, a judgment of clinical impact was made. RESULTS: Twenty patients (3.0%) fulfilled imaging ARVC criteria. Thirty (4.6%) had a potential ARVC mimic, of which 25 (3.8%) were considered clinically important: cardiac displacement (n=17), RV overload (n=7) and non-ARVC like myocardial scarring (n=4). One patient had two mimics; one patient had dual pathology with important mimic and ARVC. RV overload and scarring conditions were always thought clinically important whilst the importance of cardiac displacement depended on the degree of displacement from severe (partial absence of pericardium) to epiphenomenon (minor kyphoscoliosis). CONCLUSIONS: Some patients referred for CMR with suspected ARVC fulfil ARVC imaging criteria (3%) but more have otherwise unrecognised diseases (4.6%) mimicking potentially ARVC. Clinical assessment should reflect this, emphasising the assessment and/or exclusion of potential mimics in parallel with the detection of ARVC major and minor criteria