1,200 research outputs found
Mineralogical Alterations During Laboratory-scale Carbon Sequestration Experiments for the Illinois Basin
AbstractDuring geological sequestration of carbon dioxide, the injected CO2 will react with formation fluids and rocks in the injection zone and overlying cap rocks. The resulting acidification of the fluids may result in the dissolution of solid phases and the formation of new solid phases which can cause changes in rock composition and overall fabric. We are conducting laboratory-scale geochemical and mineralogical studies on reservoir and cap rock samples in the Illinois Basin that complement the on-going Illinois Basin - Decatur Project (IBDP), a large-scale one million tonne demonstration of geologic sequestration in the Mt Simon Sandstone, Illinois USA. Mt. Simon Sandstone, Eau Clare Shale, and Knox Supergroup samples from the IBDP injection and deep monitoring wells and locations with rocks analogous to those at the IBDP site have been selected for simulated reactions using synthetic brine and CO2 in modified Parr pressure reactors at pressure and temperature conditions that correspond to ambient reservoir conditions (9.87 to 20.7MPa and 38 to 50°C) and for varying amounts of time (1 to 9 months). Using petrographic techniques and XRD analysis, samples have been analyzed before and after reactor experiments to define the mineralogical and textural baseline and report observed changes. Brine composition has also been analyzed for geochemical changes. The React® and Differential Evolution geochemical modeling programs are being used to simulate changes in mineral mass and brine chemistry. Post-reaction analyses of rock and brine samples from the Mt. Simon Sandstone show evidence of dissolution of diagenetic clays, increased porosity, and possible illitization of clay minerals. Three, six, and nine month post-reaction Eau Claire Shale rock and brine sample analyses indicate some degree of brine-rock-CO2 reaction by showing weathered illite, mixed clay, feldspar, biotite, and pyrite crystals. Post-reaction Potosi Dolomite rock and brine samples show evidence of dissolution of dolomite. Overall, petrographic and geochemical observations from these experiments suggest that the Mt. Simon Sandstone reservoir and Eau Claire cap rock system serve as good CO2 sequestration site. The competency of the Knox Supergroup as a CO2 sequestration target is still under investigation
Effect of magnetic and non-magnetic impurities on highly anisotropic superconductivity
We generalize Abrikosov-Gor'kov solution of the problem of weakly coupled
superconductor with impurities on the case of a multiband superconductor with
arbitrary interband order parameter anisotropy, including interband sign
reversal of the order parameter. The solution is given in terms of the
effective (renormalized) coupling matrix and describes not only
suppression but also renormalization of the superconducting gap basically at
all temperatures. In many limiting cases we find analytical solutions for the
critical temperature suppression. We illustrate our results by numerical
calculations for two-band model systems.Comment: 18 pages (12pt) RevTeX, 4 postscript figure
Modern topics in theoretical nuclear physics
Over the past five years there have been profound advances in nuclear physics
based on effective field theory and the renormalization group. In this brief,
we summarize these advances and discuss how they impact our understanding of
nuclear systems and experiments that seek to unravel their unknowns. We discuss
future opportunities and focus on modern topics in low-energy nuclear physics,
with special attention to the strong connections to many-body atomic and
condensed matter physics, as well as to astrophysics. This makes it an exciting
era for nuclear physics.Comment: 8 pages, 1 figure, prepared for the Nuclear Physics Town Hall Meeting
at TRIUMF, Sept. 9-10, 2005, comments welcome, references adde
Affective Man-Machine Interface: Unveiling human emotions through biosignals
As is known for centuries, humans exhibit an electrical profile. This profile is altered through various psychological and physiological processes, which can be measured through biosignals; e.g., electromyography (EMG) and electrodermal activity (EDA). These biosignals can reveal our emotions and, as such, can serve as an advanced man-machine interface (MMI) for empathic consumer products. However, such a MMI requires the correct classification of biosignals to emotion classes. This chapter starts with an introduction on biosignals for emotion detection. Next, a state-of-the-art review is presented on automatic emotion classification. Moreover, guidelines are presented for affective MMI. Subsequently, a research is presented that explores the use of EDA and three facial EMG signals to determine neutral, positive, negative, and mixed emotions, using recordings of 21 people. A range of techniques is tested, which resulted in a generic framework for automated emotion classification with up to 61.31% correct classification of the four emotion classes, without the need of personal profiles. Among various other directives for future research, the results emphasize the need for parallel processing of multiple biosignals
A New Species of Giant Sengi or Elephant-Shrew (Genus \u3cem\u3eRhynchocyon\u3c/em\u3e) Highlights the Exceptional Biodiversity of the Udzungwa Mountains of Tanzania
A new species of sengi, or elephant-shrew, is described. It was discovered in the northern Udzungwa Mountains of Tanzania in 2005. Sengis (Order Macroscelidea, super-cohort Afrotheria) include four genera and 15 species of mammals that are endemic to Africa. This discovery is a significant contribution to the systematics of this small order. Based on 49 camera trap images, 40 sightings and five voucher specimens, the new sengi is diurnal and distinguished from the other three species of Rhynchocyon by a grizzled grey face, pale yellow to cream chest and chin, orange-rufous sides, maroon back and jet-black lower rump and thighs. The body weight of the new species is about 700 g, which is 25–50% greater than any other giant sengi. The new Rhynchocyon is only known from two populations that cover about 300 km2 of montane forest. It has an estimated density of 50–80 individuals km−2. This discovery has important implications for the conservation of the high biodiversity that is found in the forests of the Eastern Arc Mountains
Effect of short-term versus long-term grassland management and seasonal variation in organic and conventional dairy farming on the composition of bulk tank milk
Bulk tank milk from 28 dairy farms was sampled every second month for 2 yr to assess the effects of grassland management, production system and season on milk fatty acid (FA) composition, concentrations of fat-soluble vitamins, Se, and milk sensory quality. Grassland management varied in terms of time since establishment. Short-term grassland management (SG) was defined as establishment or reseeding every fourth year or more often, and long-term grassland management (LG) was defined as less frequent establishment or reseeding. Fourteen organic (ORG) dairy farms with either short-term or long-term grassland management were paired with 14 conventional (CON) farms with respect to grassland management. Within ORG farms, SG farms differed from LG farms in herbage botanical composition, but not in concentrate FA concentrations, dry matter intake, or milk yield. Within CON farms, herbage composition, concentrate FA concentrations, dry matter intake, and milk yield showed no or insignificant variations. The ORG farms differed from CON farms in herbage botanical composition, concentrate FA concentrations, concentrate intake, and milk yield. Compared with ORG-LG farms, ORG-SG farms produced milk fat with higher proportions of C10:0 and C12:0 associated with higher herbage proportions of legumes (Fabaceae) and lower proportions of other dicotyledon families. Compared with milk from CON farms, milk fat from ORG farms had higher proportions of most saturated FA and all n-3 FA, but lower proportions of C18:0 and C18:1 cis-9 associated with higher forage proportion and differences in concentrations of FA in concentrates. Compared with the outdoor-feeding periods, the indoor feeding periods yielded milk fat with higher proportions of most short-chain and medium-chain FA and lower proportions of most C18-FA associated with grazing and higher forage proportions. Milk concentrations of α-tocopherol and β-carotene were lower during the grazing periods. Inclusion of fishmeal in organic concentrates may explain higher Se concentrations in organically produced milk. Milk sensory quality was not affected in this study. In conclusion, grassland management had minor effects on milk composition, and differences between ORG farms and CON farms may be explained by differences in concentrate intake and concentrate FA concentrations. Milk produced on ORG farms versus CON farms and milk produced during the outdoor versus indoor feeding periods had potential health benefits due to FA composition. In contrast, the higher milk-fat proportions of saturated FA in milk from ORG farms may be perceived as negative for human health
Measurement of (anti)deuteron and (anti)proton production in DIS at HERA
The first observation of (anti)deuterons in deep inelastic scattering at HERA
has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV
using an integrated luminosity of 120 pb-1. The measurement was performed in
the central rapidity region for transverse momentum per unit of mass in the
range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in
terms of the coalescence model. The (anti)deuteron production yield is smaller
than the (anti)proton yield by approximately three orders of magnitude,
consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.
Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV
We report the results of a study of color coherence effects in ppbar
collisions based on data collected by the D0 detector during the 1994-1995 run
of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8
TeV. Initial-to-final state color interference effects are studied by examining
particle distribution patterns in events with a W boson and at least one jet.
The data are compared to Monte Carlo simulations with different color coherence
implementations and to an analytic modified-leading-logarithm perturbative
calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters
Measurement of the p-pbar -> Wgamma + X cross section at sqrt(s) = 1.96 TeV and WWgamma anomalous coupling limits
The WWgamma triple gauge boson coupling parameters are studied using p-pbar
-> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were
collected with the DO detector from an integrated luminosity of 162 pb^{-1}
delivered by the Fermilab Tevatron Collider. The cross section times branching
fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV
and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum)
pb. The one-dimensional 95% confidence level limits on anomalous couplings are
-0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.Comment: Submitted to Phys. Rev. D Rapid Communication
Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using Kinematic Characteristics of Lepton + Jets Events
We present a measurement of the top quark pair ttbar production cross section
in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb**{-1}
of data collected by the DO detector at the Fermilab Tevatron Collider. We
select events with one charged lepton (electron or muon), large missing
transverse energy, and at least four jets, and extract the ttbar content of the
sample based on the kinematic characteristics of the events. For a top quark
mass of 175 GeV, we measure sigma(ttbar) = 6.7 {+1.4-1.3} (stat) {+1.6- 1.1}
(syst) +/-0.4 (lumi) pb, in good agreement with the standard model prediction.Comment: submitted to Phys.Rev.Let
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