74 research outputs found
On the importance of relative permeability data for estimating CO2 injectivity in brine aquifers
Performance assessment of possible CO2 storage schemes is often investigated through numerical simulation of the CO2 injection process. An important criterion of interest is the maximum sustainable injection rate. Relevant numerical models generally employ a multi-phase extension to Darcy's law, requiring data concerning the evolution of relative permeability for CO2 and brine mixtures with increasing CO2 saturation. Relative permeability data is acutely scarce for many geographical regions of concern and often cited as a major source of uncertainty. However, such data is expensive and time consuming to acquire. With a view to improving our understanding concerning the significance of relative permeability uncertainty on injectivity, this article presents a sensitivity analysis of sustainable CO2 injection rate with respect to permeability, porosity and relative permeability. Based on available relative permeability data obtained from 25 sandstone and carbonate cores discussed in the literature, injectivity uncertainty associated with relative permeability is found to be as high as Âą57% for open aquifers and low permeability closed aquifers (100 mD), aquifer compressibility plays a more important role and the uncertainty due to relative permeability is found to reduce to Âą6%
A randomised controlled trial of prehabilitation in patients undergoing elective cardiac surgery
The feasibility, safety and efficacy of prehabilitation in adult patients awaiting elective cardiac surgery are unknown. A total of 180 participants undergoing elective cardiac surgery were allocated randomly to receive either standard pre-operative care or prehabilitation, consisting of pre-operative exercise and inspiratory muscle training. The primary outcome was change in six-minute walk test distance from baseline to pre-operative assessment. Secondary outcomes included change in inspiratory muscle strength (maximal inspiratory pressure); sarcopenia (handgrip strength); quality of life and compliance. Safety outcomes were pre-specified surgical and pulmonary complications and adverse events. All outcomes were assessed at baseline; at pre-operative assessment; and 6 and 12âweeks following surgery. Mean (SD) age was 64.7 (10.2) years; 33/180 (18%) were women. In total, 65/91 (71.4%) participants who were allocated to prehabilitation attended at least four of eight supervised in-hospital exercise classes; participants aged >â50âyears were more likely than younger participants to attend (odds ratio (95%CI) of 4.6 (1.0â25.1)). Six-minute walk test was not significantly different between groups (mean difference (95%CI) -7.8âm (-30.6â15.0), pâ=â0.503) in the intention-to-treat analysis. Subgroup analyses based on tests for interaction indicated improvements in six-minute walk test distance were larger amongst sarcopenic patients in the prehabilitation group (pâ=â0.004). Change in maximal inspiratory pressure from baseline to all time-points was significantly greater in the prehabilitation group, with the greatest mean difference (95%CI) observed 12âweeks after surgery (10.6 cmH2O (4.6â16.6) cmH2O, pâ<â0.001). There were no differences in handgrip strength or quality of life up to 12âweeks after surgery. There was no significant difference in postoperative mortality (one death in each group), surgical or pulmonary complications. Of 71 pre-operative adverse events, six (8.5%) were related to prehabilitation. The combination of exercise and inspiratory muscle training in a prehabilitation intervention before cardiac surgery was not superior to standard care in improving functional exercise capacity measured by six-minute walk test distance pre-operatively. Future trials should target patients living with sarcopenia and include inspiratory muscle strength training
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV
Isolated photon production is measured in proton-proton and lead-lead
collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the
pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80
GeV with the CMS detector at the LHC. The measured ET spectra are found to be
in good agreement with next-to-leading-order perturbative QCD predictions. The
ratio of PbPb to pp isolated photon ET-differential yields, scaled by the
number of incoherent nucleon-nucleon collisions, is consistent with unity for
all PbPb reaction centralities.Comment: Submitted to Physics Letters
Unexplored therapeutic opportunities in the human genome
A large proportion of biomedical research and the development of therapeutics is focused on a small fraction of the human genome. In a strategic effort to map the knowledge gaps around proteins encoded by the human genome and to promote the exploration of currently understudied, but potentially druggable, proteins, the US National Institutes of Health launched the Illuminating the Druggable Genome (IDG) initiative in 2014. In this article, we discuss how the systematic collection and processing of a wide array of genomic, proteomic, chemical and disease-related resource data by the IDG Knowledge Management Center have enabled the development of evidence-based criteria for tracking the target development level (TDL) of human proteins, which indicates a substantial knowledge deficit for approximately one out of three proteins in the human proteome. We then present spotlights on the TDL categories as well as key drug target classes, including G protein-coupled receptors, protein kinases and ion channels, which illustrate the nature of the unexplored opportunities for biomedical research and therapeutic development. ĂŠ 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved
Erratum: Unexplored therapeutic opportunities in the human genome (Nature reviews. Drug discovery (2018) 17 5 (317-332))
This corrects the article DOI: 10.1038/nrd.2018.14
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 Ă 10â8) 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 Ă 10â10; 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 = â0.32, SE = 0.05, P = 6.5 Ă 10â12), 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 Parkinsonâs 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
Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV
Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7ââfbâ1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale
Measurement of the inclusive production cross sections for forward jets and for dijet events with one forward and one central jet in pp collisions at sqrt(s) = 7 TeV
The inclusive production cross sections for forward jets, as well for jets in
dijet events with at least one jet emitted at central and the other at forward
pseudorapidities, are measured in the range of transverse momenta pt = 35-150
GeV/c in proton-proton collisions at sqrt(s) = 7 TeV by the CMS experiment at
the LHC. Forward jets are measured within pseudorapidities 3.2<|eta|<4.7, and
central jets within the |eta|<2.8 range. The double differential cross sections
with respect to pt and eta are compared to predictions from three approaches in
perturbative quantum chromodynamics: (i) next-to-leading-order calculations
obtained with and without matching to parton-shower Monte Carlo simulations,
(ii) PYTHIA and HERWIG parton-shower event generators with different tunes of
parameters, and (iii) CASCADE and HEJ models, including different non-collinear
corrections to standard single-parton radiation. The single-jet inclusive
forward jet spectrum is well described by all models, but not all predictions
are consistent with the spectra observed for the forward-central dijet events.Comment: Submitted to the Journal of High Energy Physic
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