The ALSTOM benchmark challenge on gasifier control

Integrated gasification combined cycle power plants are being developed around the world to provide environmentally clean and efficient power generation from coal. As part of the UK’s Clean Coal Power Generation Group, ALSTOM (formerly GEC ALSTHOM ) has undertaken a detailed feasibility study on the development of a small-scale prototype integrated plant (PIP), based on the air-blown gasification cycle. In pursuit of this goal the ALSTOM Power Technology Centre (formerly the GEC ALSTHOM Mechanical Engineering Centre) has produced a comprehensive dynamic model and control philosophy for the PIP. The gasifier is one component of the model which, being a highly coupled multi-variable system with five inputs (coal, limestone, air, steam and char extraction) and four outputs (pressure, temperature, bed mass and gas quality), has been found to be particularly difficult to control. For this reason the gasifier, together with its associated control specification, operating constraints and various disturbance characteristics, has been selected as the subject for this control challenge. This paper provides a brief background to the problem and describes the control specification and closed-loop tests to be performed

Simultaneous NICER and NuSTAR observations of the Ultracompact X-ray Binary 4U 0614+091

We present the first joint NuSTAR and NICER observations of the ultracompact X-ray binary 4U 0614+091. This source shows quasiperiodic flux variations on the timescale of ∼days. We use reflection modeling techniques to study various components of the accretion system as the flux varies. We find that the flux of the reflected emission and the thermal components representing the disk and the compact object trend closely with the overall flux. However, the flux of the power-law component representing the illuminating X-ray corona scales in the opposite direction, increasing as the total flux decreases. During the lowest flux observation, we see evidence of accretion disk truncation from roughly 6 gravitational radii to 11.5 gravitational radii. This is potentially analogous to the truncation seen in black hole low-mass X-ray binaries, which tends to occur during the low/hard state at sufficiently low Eddington ratios

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

The genetic architecture of the human cerebral cortex

INTRODUCTION The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure. RATIONALE To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations. RESULTS We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness). Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness. To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity. We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism. CONCLUSION This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function

A multiple infusion start time (MIST) protocol for stable isotope studies of fetal blood

A new approach utilizing multiple infusion start times for two stable isotopes of leucine was applied to seven pregnancies in order to assess equilibration times for isotopic studies when a single fetal blood sample is available. Two infusates, one containing L-[1-13C]-leucine and the other L-[5,5,5-D3]-leucine, were given as a primed constant infusion in the maternal circulation at fetal blood sampling (FBS). In five patients L-[1-13C]-leucine infusion was started at time zero (T0) whereas L-[5,5,5-D3]-leucine infusion began 30 min later, and both were continued until the umbilical sample was obtained at 149.7 \ub1 8.8 min. In order to assure non-steady state conditions, in two patients the first infusion started at T0 and the second 17 and 6 min before FBS was performed at 115 and 154 min, respectively. The fetal/maternal ratio for L-[5,5,5-D3]-leucine over the fetal/maternal ratio for L[1-13C]-leucine was 0.98 \ub1 0.03, indicating steady state conditions for both infusions for the first six patients. In the last patient the ratio was 0.51, indicative of non-steady state conditions for the shortest infusion time. Our results show that a single fetal sample can provide data for fetal amino acid enrichments reflecting multiple time points. Leucine steady state is achieved 20 min after a primed continuous infusion both in the maternal and fetal circulations