Pop-up Langmuir probe diagnostic in the water cooled divertor of Wendelstein 7-X.

The design, development, and successful implementation of pop-up Langmuir probes installed in the water-cooled divertor of W7-X are described. The probes are controlled by drive coils (actuators) installed behind the divertor plates. These drive coils make use of the magnetic field in W7-X to move the probe tips into and out of the plasma. The drive coils were installed in the vacuum vessel after extensively testing the durability of the coils and analyzing the criteria for safe operation. The probe design is carefully tailored for each of the 36 probe tips in order to be suitable for the different magnetic field configurations used in W7-X and ensure that the probes do not present leading edges to the magnetic flux tubes. An electronic bridge circuit is used for measurement to compensate for the effects of signal propagation time on the long cable lengths used. The diagnostic is integrated with the segment control of W7-X for automated operation and control of the diagnostic. The evaluation of the results from the plasma operation is presented after accounting for appropriate sheath expansion for negative bias voltage on the probes.

Initial operation and data processing on a system for real-time evaluation of Thomson scattering signals on the Large Helical Device.

A scalable system for real-time analysis of electron temperature and density based on signals from the Thomson scattering diagnostic, initially developed for and installed on the NSTX-U experiment, was recently adapted for the Large Helical Device and operated for the first time during plasma discharges. During its initial operation run, it routinely recorded and processed signals for four spatial points at the laser repetition rate of 30 Hz, well within the system's rated capability for 60 Hz. We present examples of data collected from this initial run and describe subsequent adaptations to the analysis code to improve the fidelity of the temperature calculations.

The Langmuir probe system in the Wendelstein 7-X test divertor.

The design and evaluation of the Langmuir probe system used in the first divertor operation phase of Wendelstein 7-X is described. The probes are integrated into the target plates and have individually facetted surfaces to keep the angle of incidence of the magnetic field within an appropriate range for different magnetic configurations. Multiple models for the derivation of plasma parameters from current-voltage characteristics are introduced. These are analyzed with regard to their assumptions and limitations, generalized, and adapted to our use case. A detailed comparison is made to determine the most suitable model. It is found that the choice of model has a large impact, for example, resulting in a change in the inferred temperatures of up to a factor two. This evaluation is implemented in a Bayesian modeling framework and automated to allow for joint analysis with other diagnostics and a replacement of ad hoc assumptions. We rigorously treat parameter uncertainties, revealing strong correlations between them. General and flexible model formulations permit an expansion to additional effects.

First Observation of a Stable Highly Dissipative Divertor Plasma Regime on the Wendelstein 7-X Stellarator.

For the first time, the optimized stellarator Wendelstein 7-X has operated with an island divertor. An operation regime in hydrogen was found in which the total plasma radiation approached the absorbed heating power without noticeable loss of stored energy. The divertor thermography recorded simultaneously a strong reduction of the heat load on all divertor targets, indicating almost complete power detachment. This operation regime was stably sustained over several energy confinement times until the preprogrammed end of the discharge. The plasma radiation is mainly due to oxygen and is located at the plasma edge. This plasma scenario is reproducible and robust at various heating powers, plasma densities, and gas fueling locations. These experimental results show that the island divertor concept actually works and displays good power dissipation potential, producing a promising exhaust concept for the stellarator reactor line.

A microfluidic platform for the characterisation of membrane active antimicrobials.

The spread of bacterial resistance against conventional antibiotics generates a great need for the discovery of novel antimicrobials. Polypeptide antibiotics constitute a promising class of antimicrobial agents that favour attack on bacterial membranes. However, efficient measurement platforms for evaluating their mechanisms of action in a systematic manner are lacking. Here we report an integrated lab-on-a-chip multilayer microfluidic platform to quantify the membranolytic efficacy of such antibiotics. The platform is a biomimetic vesicle-based screening assay, which generates giant unilamellar vesicles (GUVs) in physiologically relevant buffers on demand. Hundreds of these GUVs are individually immobilised downstream in physical traps connected to separate perfusion inlets that facilitate controlled antibiotic delivery. Antibiotic efficacy is expressed as a function of the time needed for an encapsulated dye to leak out of the GUVs as a result of antibiotic treatment. This proof-of-principle study probes the dose response of an archetypal polypeptide antibiotic cecropin B on GUVs mimicking bacterial membranes. The results of the study provide a foundation for engineering quantitative, high-throughput microfluidics devices for screening antibiotics.

MR1-restricted mucosal-associated invariant T (MAIT) cells respond to mycobacterial vaccination and infection in nonhuman primates.

Studies on mucosal-associated invariant T cells (MAITs) in nonhuman primates (NHP), a physiologically relevant model of human immunity, are handicapped due to a lack of macaque MAIT-specific reagents. Here we show that while MR1 ligand-contact residues are conserved between human and multiple NHP species, three T-cell receptor contact-residue mutations in NHP MR1 diminish binding of human MR1 tetramers to macaque MAITs. Construction of naturally loaded macaque MR1 tetramers facilitated identification and characterization of macaque MR1-binding ligands and MAITs, both of which mirrored their human counterparts. Using the macaque MR1 tetramer we show that NHP MAITs activated in vivo in response to both Bacillus Calmette-Guerin vaccination and Mycobacterium tuberculosis infection. These results demonstrate that NHP and human MR1 and MAITs function analogously, and establish a preclinical animal model to test MAIT-targeted vaccines and therapeutics for human infectious and autoimmune disease.

Molecular dynamics simulations and Kelvin probe force microscopy to study of cholesterol-induced electrostatic nanodomains in complex lipid mixtures.

The molecular arrangement of lipids and proteins within biomembranes and monolayers gives rise to complex film morphologies as well as regions of distinct electrical surface potential, topographical and electrostatic nanoscale domains. To probe these nanodomains in soft matter is a challenging task both experimentally and theoretically. This work addresses the effects of cholesterol, lipid composition, lipid charge, and lipid phase on the monolayer structure and the electrical surface potential distribution. Atomic force microscopy (AFM) was used to resolve topographical nanodomains and Kelvin probe force microscopy (KPFM) to resolve electrical surface potential of these nanodomains in lipid monolayers. Model monolayers composed of dipalmitoylphosphatidylcholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1,2-dioleoyl-sn-glycero-3-[phospho-rac-(3-lysyl(1-glycerol))] (DOPG), and cholesterol were studied. It is shown that cholesterol changes nanoscale domain formation, affecting both topography and electrical surface potential. The molecular basis for differences in electrical surface potential was addressed with atomistic molecular dynamics (MD). MD simulations are compared the experimental results, with 100 s of mV difference in electrostatic potential between liquid-disordered bilayer (Ld, less cholesterol and lower chain order) and a liquid-ordered bilayer (Lo, more cholesterol and higher chain order). Importantly, the difference in electrostatic properties between Lo and Ld phases suggests a new mechanism by which membrane composition couples to membrane function.

Onion-peeling inversion of stellarator images.

An onion-peeling technique is developed for inferring the emissivity profile of a stellarator plasma from a two-dimensional image acquired through a CCD or CMOS camera. Each pixel in the image is treated as an integral of emission along a particular line-of-sight. Additionally, the flux surfaces in the plasma are partitioned into discrete layers, each of which is assumed to have uniform emissivity. If the topology of the flux surfaces is known, this construction permits the development of a system of linear equations that can be solved for the emissivity of each layer. We present initial results of this method applied to wide-angle visible images of the Columbia Neutral Torus (CNT) stellarator plasma.

Effects of diet forage source and neutral detergent fiber content on milk production of dairy cattle and methane emissions determined using GreenFeed and respiration chamber techniques.

Strategies to mitigate greenhouse gas emissions from dairy cattle are unlikely to be adopted if production or profitability is reduced. The primary objective of this study was to examine the effects of high maize silage (MS) versus high grass silage (GS) diets, without or with added neutral detergent fiber (NDF) on milk production and methane emission of dairy cattle, using GreenFeed (GF) or respiration chamber (RC) techniques for methane emission measurements. Experiment 1 was 12wk in duration with a randomized block continuous design and 40 Holstein cows (74d in milk) in free-stall housing, assigned to 1 of 4 dietary treatments (n=10 per treatment), according to calving date, parity, and milk yield. Milk production and dry matter intake (DMI) were measured daily, and milk composition measured weekly, with methane yield (g/kg of DMI) estimated using a GF unit (wk 10 to 12). Experiment 2 was a 4×4 Latin square design with 5-wk periods and 4 dairy cows (114d in milk) fed the same 4 dietary treatments as in experiment 1. Measurements of DMI, milk production, and milk composition occurred in wk 4, and DMI, milk production, and methane yield were measured for 2d in RC during wk 5. Dietary treatments for both experiments were fed as total mixed rations offered ad libitum and containing 500g of silage/kg of dry matter composed (DM basis) of either 75:25 MS:GS (MS) or 25:75 MS:GS (GS), without or with added NDF from chopped straw and soy hulls (+47g of NDF/kg of dry matter). In both experiments, compared with high GS, cows fed high MS had a higher DMI, greater milk production, and lower methane yield (24% lower in experiment 1 using GF and 8% lower in experiment 2 using RC). Added NDF increased (or tended to increase) methane yield for high MS, but not high GS diets. In the separate experiments, the GF and RC methods detected similar dietary treatment effects on methane emission (expressed as g/d and g/kg of DMI), although the magnitude of the differences varied between experiments. Overall methane emission and yield were 448g/d and 20.9g/kg of DMI for experiment 1 using GF and 458g/d and 23.8g/kg of DMI for experiment 2 using RC, respectively.

Effects of forage source and extruded linseed supplementation on methane emissions from growing dairy cattle of differing body weights.

Changes in diet carbohydrate amount and type (i.e., starch vs. fiber) and dietary oil supplements can affect ruminant methane emissions. Our objectives were to measure methane emissions, whole-tract digestibility, and energy and nitrogen utilization from growing dairy cattle at 2 body weight (BW) ranges, fed diets containing either high maize silage (MS) or high grass silage (GS), without or with supplemental oil from extruded linseed (ELS). Four Holstein-Friesian heifers aged 13 mo (BW range from start to finish of 382 to 526 kg) were used in experiment 1, whereas 4 lighter heifers aged 12 mo (BW range from start to finish of 292 to 419 kg) were used in experiment 2. Diets were fed as total mixed rations with forage dry matter (DM) containing high MS or high GS and concentrates in proportions (forage:concentrate, DM basis) of either 75:25 (experiment 1) or 60:40 (experiment 2), respectively. Diets were supplemented without or with ELS (Lintec, BOCM Pauls Ltd., Wherstead, UK; 260 g of oil/kg of DM) at 6% of ration DM. Each experiment was a 4 × 4 Latin square design with 33-d periods, with measurements during d 29 to 33 while animals were housed in respiration chambers. Heifers fed MS at a heavier BW (experiment 1) emitted 20% less methane per unit of DM intake (yield) compared with GS (21.4 vs. 26.6, respectively). However, when repeated with heifers of a lower BW (experiment 2), methane yield did not differ between the 2 diets (26.6g/kg of DM intake). Differences in heifer BW had no overall effect on methane emissions, except when expressed as grams per kilogram of digestible organic matter (OMD) intake (32.4 vs. 36.6, heavy vs. light heifers). Heavier heifers fed MS in experiment 1 had a greater DM intake (9.4kg/d) and lower OMD (755 g/kg), but no difference in N utilization (31% of N intake) compared with heifers fed GS (7.9 kg/d and 799 g/kg, respectively). Tissue energy retention was nearly double for heifers fed MS compared with GS in experiment 1 (15 vs. 8% of energy intake, respectively). Heifers fed MS in experiment 2 had similar DM intake (7.2 kg/d) and retention of energy (5% of intake energy) and N (28% of N intake), compared with GS-fed heifers, but OMD was lower (741 vs. 765 g/kg, respectively). No effect of ELS was noted on any of the variables measured, irrespective of animal BW, and this was likely due to the relatively low amount of supplemental oil provided. Differences in heifer BW did not markedly influence dietary effects on methane emissions. Differences in methane yield were attributable to differences in dietary starch and fiber composition associated with forage type and source.

Self-selecting fluid intake while maintaining high carbohydrate availability does not impair half-marathon performance.

We aimed to test the hypothesis that self-selecting fluid intake but maintaining high exogenous CHO availability (60 g/h) does not compromise half-marathon performance. 15 participants completed 3 half-marathons while drinking a 6% CHO solution to guidelines (DRINK) or a non-caloric solution in self-selected volumes when consuming 3×glucose (20 g) gels (G-GEL) or glucose-fructose (13 g glucose+7 g fructose) gels (GF-GEL) per hour. Fluid intake (DRINK: 1 557±182, G-GEL: 473±234, GF-GEL: 404±144 ml) and percent body mass loss (DRINK: - 0.8±0.9, G-GEL: - 2.0±0.6, GF-GEL: -2.3±1.1) were different (P<0.05) between conditions, though race time did not differ (DRINK: 110.6±14.4, G-GEL: 110.3±14.6, GF-GEL: 113.7±12.8 min). In G-GEL, there was a positive correlation (P<0.05) between body mass loss and race time. Plasma glucose was lower (P<0.05) in GF-GEL compared with other conditions, and total CHO oxidation (DRINK: 3.2±0.5, G-GEL: 3.0±0.4, GF-GEL: 2.6±0.4 g/min) was lower (P=0.06) in this trial. Self-selecting fluid intake but maintaining high CHO availability does not impair half-marathon performance. Additionally, consuming glucose-fructose mixtures in sub-optimal amounts reduces plasma glucose and total rates of CHO oxidation.

Activation of the mitochondrial caspase pathway and subsequent calpain activation in monkey RPE cells cultured under zinc depletion.

PURPOSE: Decreased zinc levels in the macula are reported in patients with age-related macular degeneration, and the zinc chelator N,N,N',N'-tetrakis (2- pyridylmethyl) ethylenediamine) (TPEN) causes death of human retinal pigment epithelial (RPE) cells. The purpose of the present study was to investigate signal transduction pathways during cell death initiated by TPEN, using monkey RPE cells. METHODS: RPE cells were cultured with TPEN. Activation of calpains and caspases, and proteolysis of their substrates were detected by immunoblotting. Incubation of calpain inhibitor SNJ-1945 or caspase inhibitor z-VAD-fmk was used to confirm activation of specific proteases. RESULTS: TPEN caused a time-dependent decrease in viable RPE cells. Cell death was accompanied by activation of calpain-1, caspase-9, and caspase-3. SNJ-1945 inhibited calpain activation and slightly inhibited caspase-9 activation. z-VAD-fmk inhibited caspases and calpain-1 activation. TPEN did not activate caspase-12. CONCLUSIONS: Relative zinc deficiency in RPE cells causes activation of cytosolic calpain and mitochondrial caspase pathways without ER stress.

Gastrointestinal tract development in red deer (Cervus elaphus) calves from 1 to 12 months of age.

This study provides a detailed description of the development of the gastrointestinal tract (GIT) of farmed red deer (Cervus elaphus) calves over the first 12 months of age. GIT development was measured using a combination of computerised tomography (CT) scanning and traditional slaughter plus dissection techniques. Red deer calves of a known birth date were randomly assigned to two treatment groups. A group of five animals were repeatedly CT scanned at 31, 63, 92, 135, 207, 275 and 351 days of age to identify GIT organs and determine their volume. From a group of 20 animals, subsets of four individuals were also scanned at corresponding ages (except 135 days of age). They were immediately euthanised and dissected after CT scanning to compare CT-scanned results with actual anatomical measurements. Individual organ weights were compared with their respective organ volumes determined by CT scanning and were found to have a strong, positive relationship. The combined rumen and reticulum (RR) CT-scanned volume was compared with its volume determined by the water-displacement technique and this also showed good correlation between the two techniques (R = 0.92). The allometric growth rates of organs, relative to animal live weight gains, in descending order, were the rumen, omasum, reticulum, abomasum, caecum blind sac, kidneys, spleen and liver. The red deer GIT was continuing to grow and develop when the last measurement was taken at 351 days of age. The greatest growth of the RR, when expressed in terms of empty weight, was between 31 and 92 days of age. Compared with sheep and cattle, it appears that the red deer have a similar or greater rate of RR development up until approximately 60 to 90 days of age; however, the final increments of GIT maturity in deer may take longer to complete, with the empty weight of the RR gaining 7.5 g/day between 275 and 351 days of age. CT scanning was validated in this study as a viable technique to follow GIT development in the same animals over time, and it provided novel information on allometric organ growth. The success of CT scanning highlights the potential future use of diagnostic imaging for GIT development studies.

Density functional theory based screening of ternary alkali-transition metal borohydrides: a computational material design project.

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M(1)); and 1 alkali, alkaline earth or 3d/4d transition metal atom (M(2)) plus two to five (BH(4))(-) groups, i.e., M(1)M(2)(BH(4))(2-5), using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M(1)(Al/Mn/Fe)(BH(4))(4), (Li/Na)Zn(BH(4))(3), and (Na/K)(Ni/Co)(BH(4))(3) alloys are found to be the most promising, followed by selected M(1)(Nb/Rh)(BH(4))(4) alloys.

Tumor lysis syndrome occurring after the administration of rituximab for posttransplant lymphoproliferative disorder.

Tumor lysis syndrome (TLS) may occur after the administration of rituximab for lymphoproliferative disorders. We describe the case of a heart transplant recipient who developed TLS after a single dose of rituximab for the treatment of posttransplant lymphoproliferative disorder. Because rituximab is being used more frequently, it is important for transplant physicians to be aware of this potential complication particularly after administering the first dose.

Pilot study of compliance with healthcare facility smoking laws in Georgia.

In 2003 Georgian Parliament restricted smoking in all healthcare facilities to designated smoking areas. Observed compliance has been low. This quantitative study of airborne nicotine and particulate concentrations in nine healthcare facilities in Tbilisi and Region Kakheti in February, 2007 was a pilot to assess the degree of noncompliance with the law and to identify potential strategies for increasing compliance. Passive sampling of nicotine and active sampling of PM(2.5) in selected healthcare facilities. None of the facilities we monitored had designated smoking areas that met the legal requirements. Fifty of the 51 samplers registered concentrations of nicotine above the level of detection. Of these, 52% showed concentrations below 1 microg/m(3) nicotine, 27% showed concentrations between 1 and 5 microg/m(3) and 20% were above 5 microg/m(3). The highest nicotine levels were found in medical staff offices, and in undesignated "informal smoking areas". These data support qualitative observations that the law restricting smoking in Georgian healthcare facilities to designated areas is poorly enforced and does not protect patients and employees from secondhand smoke. These findings suggest that Georgian law should be changed to make all healthcare institutions smoke free environments and that there is a need for tobacco control programs targeted at medical professionals in Georgia.

Temporal variation in the expression of the p53 protein in proliferating and differentiating murine erythroleukaemia cells.

Temporal changes in the expression of p53 were investigated during hexamethylene bisacetamide (HMBA)-induced differentiation of murine erythroleukaemic (MEL) cells. Cell preparations were analysed by SDS-PAGE and western immunoblotting, which detected an immunospecific band of molecular mass 53 kDa. This analysis provided semi-quantitative information. Cell extracts were analysed further by means of ELISA techniques, using a p53-specific antibody, to provide quantitative data. In time series experiments in which cells were isolated at 15, 30 and 60 min intervals, dynamic variations in the expression of the p53 protein were detected in both the untreated and the HMBA-treated MEL cells. In all cases, the effects were complex with variations in amplitude, frequency and phasing of the rhythms. The available evidence suggests that the observed patterns, like periodic variations in other systems, are modified in rhythmic fashion with respect to period and amplitude. The results add further support for our view that it is essential to consider the dynamics when interpreting the role of p53 and cellular processes in general.

Genetic diversity analysis using lowly polymorphic dominant markers: the example of AFLP in pigs.

DNA markers are commonly used for large-scale evaluation of genetic diversity in farm animals, as a component of the management of animal genetic resources. AFLP markers are useful for such studies as they can be generated relatively simply; however, challenges in analysis arise from their dominant scoring and the low level of polymorphism of some markers. This paper describes the results obtained with a set of AFLP markers in a study of 59 pig breeds. AFLP fingerprints were generated using four primer combinations (PC), yielding a total of 148 marker loci, and average harmonic mean of breed sample size was 37.3. The average proportion of monomorphic populations was 63% (range across loci: 3%-98%). The moment-based method of Hill and Weir (2004, Mol Ecol 13:895-908) was applied to estimate gene frequencies, gene diversity (F(ST)), and Reynolds genetic distances. A highly significant average F(ST) of 0.11 was estimated, together with highly significant PC effects on gene diversity. The variance of F(ST) across loci also significantly exceeded the variance expected under the hypothesis of AFLP neutrality, strongly suggesting the sensitivity of AFLP to selection or other forces. Moment estimates were compared to estimates derived from the square root estimation of gene frequency, as currently applied for dominant markers, and the biases incurred in the latter method were evaluated. The paper discusses the hypotheses underlying the moment estimations and various issues relating to the biallelic, dominant, and lowly polymorphic nature of this set of AFLP markers and to their use as compared to microsatellites for measuring genetic diversity.

Genetic diversity within and between European pig breeds using microsatellite markers.

An important prerequisite for a conservation programme is a comprehensive description of genetic diversity. The aim of this study was to use anonymous genetic markers to assess the between- and the within-population components of genetic diversity for European pig breeds at the scale of the whole continent using microsatellites. Fifty-eight European pig breeds and lines were analysed including local breeds, national varieties of international breeds and commercial lines. A sample of the Chinese Meishan breed was also included. Eleven additional breeds from a previous project were added for some analyses. Approximately 50 individuals per breed were genotyped for a maximum of 50 microsatellite loci. Substantial within-breed variability was observed, with the average expected heterozygosity and observed number of alleles per locus being 0.56 [range 0.43-0.68] and 4.5 respectively. Genotypic frequencies departed from Hardy-Weinberg expectations (P < 0.01) in 15 European populations, with an excess of homozygotes in 12 of them. The European breeds were on average genetically very distinct, with a Wright F(ST) index value of 0.21. The Neighbour-Joining tree drawn from the Reynolds distances among the breeds showed that the national varieties of major breeds and the commercial lines were mostly clustered around their breeds of reference (Duroc, Hampshire, Landrace, Large White and Piétrain). In contrast, local breeds, with the exception of the Iberian breeds, exhibited a star-like topology. The results are discussed in the light of various forces, which may have driven the recent evolution of European pig breeds. This study has consequences for the interpretation of biodiversity results and will be of importance for future conservation programmes.