306 research outputs found

    Acceleration of Oxygen Ions in Dipolarization Events: 1. CPS Distributions

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    This paper represents the second part of an investigation of the acceleration of energetic oxygen ions from encounters with a dipolarization front (DF), based on test particle tracing in the fields of an MHD simulation. In this paper, we focus on distributions in the plasma sheet boundary layer (PSBL). O+ beams close to the plasma sheet boundary are found to be less pronounced and/or delayed against the H+ beams. The reason is that these particles are accelerated by nonadiabatic motion in the duskward electric field such that O+ ions gain the same amount of energy, but only 1/4 of the speed of protons. This causes a delay and larger equatorward displacement by the E × B drift. In contrast, the O+ beams somewhat deeper inside the plasma sheet, where previously multiple proton beams were found, are accelerated at an earthward propagating DF just like H+, forming a field-aligned beam at a similar speed as the lowest-energy H+ beam. We found that the source location depends on the adiabaticity of the orbit. For larger adiabaticity, the beam ions originate initially from the outer plasma sheet, but later from the opposite PSBL or lobe, but for low adiabaticity, sources are well inside the plasma sheet. The energy gained from a single encounter of a DF is comparable to the kinetic energy associated with the front speed. Assuming maximum speeds of 500–1,000 km/s, this yields a mass dependent acceleration of about 1–5 keV for protons and 20–80 keV for oxygen ions, independent of their charge state.publishedVersio

    Near-term deployment of carbon capture and sequestration from biorefineries in the United States

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    Capture and permanent geologic sequestration of biogenic CO2 emissions may provide critical flexibility in ambitious climate change mitigation. However, most bioenergy with carbon capture and sequestration (BECCS) technologies are technically immature or commercially unavailable. Here, we evaluate low-cost, commercially ready CO2 capture opportunities for existing ethanol biorefineries in the United States. The analysis combines process engineering, spatial optimization, and lifecycle assessment to consider the technical, economic, and institutional feasibility of near-term carbon capture and sequestration (CCS). Our modeling framework evaluates least cost source-sink relationships and aggregation opportunities for pipeline transport, which can cost-effectively transport small CO2 volumes to suitable sequestration sites; 216 existing US biorefineries emit 45 Mt CO2 annually from fermentation, of which 60% could be captured and compressed for pipeline transport for under 25/tCO2Asequestrationcredit,analogoustoexistingCCStaxcredits,of25/tCO2 A sequestration credit, analogous to existing CCS tax credits, of 60/tCO2 could incent 30 Mt of sequestration and 6,900 km of pipeline infrastructure across the United States. Similarly, a carbon abatement credit, analogous to existing tradeable CO2 credits, of $90/tCO2 can incent 38 Mt of abatement. Aggregation of CO2 sources enables cost-effective long-distance pipeline transport to distant sequestration sites. Financial incentives under the low-carbon fuel standard in California and recent revisions to existing federal tax credits suggest a substantial near-term opportunity to permanently sequester biogenic CO2 This financial opportunity could catalyze the growth of carbon capture, transport, and sequestration; improve the lifecycle impacts of conventional biofuels; support development of carbon-negative fuels; and help fulfill the mandates of low-carbon fuel policies across the United States

    The provision of nutritional advice and care for cancer patients: a UK national survey of healthcare professionals.

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    PURPOSE: People living with and beyond cancer often experience nutrition-related issues and should receive appropriate advice on nutrition that is consistent and evidence based. The aim of this study was to investigate current practice for the provision of nutritional care by healthcare professionals (HCPs) from a UK national survey produced by the National Institute for Health Research (NIHR) Cancer and Nutrition Collaboration. METHODS: An online survey sent to professional groups and networks included questions on discussing nutrition, providing information, awareness of guidelines, confidence in providing nutritional advice, training and strategies for improving nutritional management. RESULTS: There were 610 HCPs who responded including nurses (31%), dietitians (25%), doctors (31%) and speech and language therapists (9%). The majority of HCPs discusses nutrition (94%) and provides information on nutrition (77%). However, only 39% of HCPs reported being aware of nutritional guidelines, and just 20% were completely confident in providing nutritional advice. Awareness of guidelines varied between the different professional groups with most but not all dietitians reporting the greatest awareness of guidelines and GPs the least (p = 0.001). Those HCPs with a greater awareness of guidelines had received training (p = 0.001) and were more likely to report complete confidence in providing nutritional advice (p = 0.001). CONCLUSION: Whilst HCPs discuss nutrition with cancer patients and may provide information, many lack an awareness of guidelines and confidence in providing nutritional advice. To ensure consistency of practice and improvements in patient care, there is scope for enhancing the provision of appropriate nutrition education and training

    Observational Constraints on Chaplygin Quartessence: Background Results

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    We derive the constraints set by several experiments on the quartessence Chaplygin model (QCM). In this scenario, a single fluid component drives the Universe from a nonrelativistic matter-dominated phase to an accelerated expansion phase behaving, first, like dark matter and in a more recent epoch like dark energy. We consider current data from SNIa experiments, statistics of gravitational lensing, FR IIb radio galaxies, and x-ray gas mass fraction in galaxy clusters. We investigate the constraints from this data set on flat Chaplygin quartessence cosmologies. The observables considered here are dependent essentially on the background geometry, and not on the specific form of the QCM fluctuations. We obtain the confidence region on the two parameters of the model from a combined analysis of all the above tests. We find that the best-fit occurs close to the Λ\LambdaCDM limit (α=0\alpha=0). The standard Chaplygin quartessence (α=1\alpha=1) is also allowed by the data, but only at the 2σ\sim2\sigma level.Comment: Replaced to match the published version, references update

    Five blood pressure loci identified by an updated genome-wide linkage scan: meta-analysis of the Family Blood Pressure Program.

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    BACKGROUND: A preliminary genome-wide linkage analysis of blood pressure in the Family Blood Pressure Program (FBPP) was reported previously. We harnessed the power and ethnic diversity of the final pooled FBPP dataset to identify novel loci for blood pressure thereby enhancing localization of genes containing less common variants with large effects on blood pressure levels and hypertension. METHODS: We performed one overall and 4 race-specific meta-analyses of genome-wide blood pressure linkage scans using data on 4,226 African-American, 2,154 Asian, 4,229 Caucasian, and 2,435 Mexican-American participants (total N = 13,044). Variance components models were fit to measured (raw) blood pressure levels and two types of antihypertensive medication adjusted blood pressure phenotypes within each of 10 subgroups defined by race and network. A modified Fisher's method was used to combine the P values for each linkage marker across the 10 subgroups. RESULTS: Five quantitative trait loci (QTLs) were detected on chromosomes 6p22.3, 8q23.1, 20q13.12, 21q21.1, and 21q21.3 based on significant linkage evidence (defined by logarithm of odds (lod) score ≥3) in at least one meta-analysis and lod scores ≥1 in at least 2 subgroups defined by network and race. The chromosome 8q23.1 locus was supported by Asian-, Caucasian-, and Mexican-American-specific meta-analyses. CONCLUSIONS: The new QTLs reported justify new candidate gene studies. They may help support results from genome-wide association studies (GWAS) that fall in these QTL regions but fail to achieve the genome-wide significance

    Planck scale effects in neutrino physics

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    We study the phenomenology and cosmology of the Majoron (flavon) models of three active and one inert neutrino paying special attention to the possible (almost) conserved generalization of the Zeldovich-Konopinski-Mahmoud lepton charge. Using Planck scale physics effects which provide the breaking of the lepton charge, we show how in this picture one can incorporate the solutions to some of the central issues in neutrino physics such as the solar and atmospheric neutrino puzzles, dark matter and a 17 keV neutrino. These gravitational effects induce tiny Majorana mass terms for neutrinos and considerable masses for flavons. The cosmological demand for the sufficiently fast decay of flavons implies a lower limit on the electron neutrino mass in the range of 0.1-1 eV.Comment: 24 pages, 1 figure (not included but available upon request), LaTex, IC/92/196, SISSA-140/92/EP, LMU-09/9

    Functional characterisation of the amyotrophic lateral sclerosis risk locus GPX3/TNIP1

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    Background Amyotrophic lateral sclerosis (ALS) is a complex, late-onset, neurodegenerative disease with a genetic contribution to disease liability. Genome-wide association studies (GWAS) have identified ten risk loci to date, including the TNIP1/GPX3 locus on chromosome five. Given association analysis data alone cannot determine the most plausible risk gene for this locus, we undertook a comprehensive suite of in silico, in vivo and in vitro studies to address this. Methods The Functional Mapping and Annotation (FUMA) pipeline and five tools (conditional and joint analysis (GCTA-COJO), Stratified Linkage Disequilibrium Score Regression (S-LDSC), Polygenic Priority Scoring (PoPS), Summary-based Mendelian Randomisation (SMR-HEIDI) and transcriptome-wide association study (TWAS) analyses) were used to perform bioinformatic integration of GWAS data (Ncases = 20,806, Ncontrols = 59,804) with ‘omics reference datasets including the blood (eQTLgen consortium N = 31,684) and brain (N = 2581). This was followed up by specific expression studies in ALS case-control cohorts (microarray Ntotal = 942, protein Ntotal = 300) and gene knockdown (KD) studies of human neuronal iPSC cells and zebrafish-morpholinos (MO). Results SMR analyses implicated both TNIP1 and GPX3 (p < 1.15 × 10−6), but there was no simple SNP/expression relationship. Integrating multiple datasets using PoPS supported GPX3 but not TNIP1. In vivo expression analyses from blood in ALS cases identified that lower GPX3 expression correlated with a more progressed disease (ALS functional rating score, p = 5.5 × 10−3, adjusted R2 = 0.042, Beffect = 27.4 ± 13.3 ng/ml/ALSFRS unit) with microarray and protein data suggesting lower expression with risk allele (recessive model p = 0.06, p = 0.02 respectively). Validation in vivo indicated gpx3 KD caused significant motor deficits in zebrafish-MO (mean difference vs. control ± 95% CI, vs. control, swim distance = 112 ± 28 mm, time = 1.29 ± 0.59 s, speed = 32.0 ± 2.53 mm/s, respectively, p for all < 0.0001), which were rescued with gpx3 expression, with no phenotype identified with tnip1 KD or gpx3 overexpression. Conclusions These results support GPX3 as a lead ALS risk gene in this locus, with more data needed to confirm/reject a role for TNIP1. This has implications for understanding disease mechanisms (GPX3 acts in the same pathway as SOD1, a well-established ALS-associated gene) and identifying new therapeutic approaches. Few previous examples of in-depth investigations of risk loci in ALS exist and a similar approach could be applied to investigate future expected GWAS findings

    Leptonic Dirac CP Violation Predictions from Residual Discrete Symmetries

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    Assuming that the observed pattern of 3-neutrino mixing is related to the existence of a (lepton) flavour symmetry, corresponding to a non-Abelian discrete symmetry group Gf, and that Gf is broken to specific residual symmetries Ge and G\u3bd of the charged lepton and neutrino mass terms, we derive sum rules for the cosine of the Dirac phase \u3b4 of the neutrino mixing matrix U. The residual symmetries considered are: i) Ge=Z2 and G\u3bd=Zn, n>2 or Zn 7Zm, n, m 652; ii) Ge=Zn, n>2 or Zn 7Zm, n, m 652 and G\u3bd=Z2; iii) Ge=Z2 and G\u3bd=Z2; iv) Ge is fully broken and G\u3bd=Zn, n>2 or Zn 7Zm, n, m 652; and v) Ge=Zn, n>2 or Zn 7Zm, n, m 652 and G\u3bd is fully broken. For given Ge and G\u3bd, the sum rules for cos \u3b4 thus derived are exact, within the approach employed, and are valid, in particular, for any Gf containing Ge and G\u3bd as subgroups. We identify the cases when the value of cos \u3b4 cannot be determined, or cannot be uniquely determined, without making additional assumptions on unconstrained parameters. In a large class of cases considered the value of cos \u3b4 can be unambiguously predicted once the flavour symmetry Gf is fixed. We present predictions for cos \u3b4 in these cases for the flavour symmetry groups Gf=S4, A4, T' and A5, requiring that the measured values of the 3-neutrino mixing parameters sin2\u3b812, sin2\u3b813 and sin2\u3b823, taking into account their respective 3\u3c3 uncertainties, are successfully reproduced. \ua9 2015 The Authors

    Toward an internally consistent astronomical distance scale

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    Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been established. We review current efforts to homogenize the Local Group's distance framework, with particular emphasis on the potential of RR Lyrae stars as distance indicators, and attempt to extend this in an internally consistent manner to cosmological distances. Calibration based on Type Ia supernovae and distance determinations based on gravitational lensing represent particularly promising approaches. We provide a positive outlook to improvements to the status quo expected from future surveys, missions, and facilities. Astronomical distance determination has clearly reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press (chapter 8 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

    The PHENIX Experiment at RHIC

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    The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix
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