425 research outputs found
Seismic Response to Injection Well Stimulation in a High-Temperature, High-Permeability Reservoir
Fluid injection into the Earth's crust can induce seismic events that cause damage to local infrastructure but also offer valuable insight into seismogenesis. The factors that influence the magnitude, location, and number of induced events remain poorly understood but include injection flow rate and pressure as well as reservoir temperature and permeability. The relationship between injection parameters and injection-induced seismicity in high-temperature, high-permeability reservoirs has not been extensively studied. Here we focus on the Ngatamariki geothermal field in the central TaupĆ Volcanic Zone, New Zealand, where three stimulation/injection tests have occurred since 2012. We present a catalog of seismicity from 2012 to 2015 created using a matched-filter detection technique. We analyze the stress state in the reservoir during the injection tests from first motion-derived focal mechanisms, yielding an average direction of maximum horizontal compressive stress (SHmax) consistent with the regional NE-SW trend. However, there is significant variation in the direction of maximum compressive stress (Ï1), which may reflect geological differences between wells. We use the ratio of injection flow rate to overpressure, referred to as injectivity index, as a proxy for near-well permeability and compare changes in injectivity index to spatiotemporal characteristics of seismicity accompanying each test. Observed increases in injectivity index are generally poorly correlated with seismicity, suggesting that the locations of microearthquakes are not coincident with the zone of stimulation (i.e., increased permeability). Our findings augment a growing body of work suggesting that aseismic opening or slip, rather than seismic shear, is the active process driving well stimulation in many environments
Joint inversion of seismic data for temperature and lithology in the Eastern Alps
The high density SWATH-D and AlpArray seismic networks provide a unique opportunity in the Eastern Alps to resolve the complex plate configuration and investigate how the crustal structure seen today reflects the dramatic changes in mountain building style and reorganisation of plate boundaries at about 20 Ma. This study complements the partner project where scattered wave tomography is applied to the same area (presented in the poster âApplying scattered wave tomography and joint inversion of high-density (SWATH D) geophysical and petrophysical datasets to unravel Eastern Alpine crustal structureâ, Tilmann et al).
In order to bring together the seismological and geological-mineralogical constraints in a probabilistic self-consistent way, we employ the joint inversion of seismological and petrophysical data sets. Receiver functions and surface wave dispersion curves, calculated in partner projects, are usually jointly inverted for elastic properties. By utilising the strengths of Markov Chain Monte Carlo inversion, we are able to instead parameterise our model by temperature and mineral assemblage. By inverting seismic data directly for the crustâs constituent mineral assemblages, we are led to a deeper understanding of intra-crustal structure, temperature, and petrophysical properties of crustal layers. A further significant advantage is in interpretation where the probabilities of certain lithologies being present allows for a more seamless integration of qualitative geological data and a reduction in interpretation biases compared to when only seismic velocities are presented
Mapping out the thermodynamic stability of a QCD equation of state with a critical point using active learning
The Beam Energy Scan Theory (BEST) collaboration's equation of state (EoS)
incorporates a 3D Ising model critical point into the Quantum Chromodynamics
(QCD) equation of state from lattice simulations. However, it contains 4 free
parameters related to the size and location of the critical region in the QCD
phase diagram. Certain combinations of the free parameters lead to acausal or
unstable realizations of the EoS that should not be considered. In this work,
we use an active learning framework to rule out pathological EoS efficiently.
We find that checking stability and causality for a small portion of the
parameters' range is sufficient to construct algorithms that perform with
96% accuracy across the entire parameter space. Though in this work we focus
on a specific case, our approach can be generalized to any EoS containing a
parameter space-class correspondence.Comment: 14 pages, 9 figure
Resolving the Eastern Alpine puzzle: Illumination of crustal structure with receiver functions and ambient noise autocorrelations
The tectonic structure of the Eastern Alps is heavily debated with successive geophysical studies that are unable to resolve areas of ambiguity (e.g., the presence of a switch in subduction polarity and differing crustal models). In order to better understand this area, we produce a high resolution Moho map of the Eastern Alps based on a dense seismic broadband array deployment (SWATH-D). Moho depths were derived from joint analysis of receiver function images of direct conversions and multiple reflections for both the SV (radial) and SH (transverse) components, which enables us to map overlapping and inclined discontinuities. Autocorrelations, derived from ambient noise, recover zero-offset reflections for a subset of stations located in the Bohemian Massif (part of the EASI transect) and provide an independent measurement of Moho depth and corroborate the receiver function results. Autocorrelations also give potential for a combined analysis to better constrain crustal average P velocities. Furthermore, an associated petrological study informs us on the implications of the eclogitisation of crustal rocks for these imaging techniques (see poster John et al âThe effect of eclogitization of crustal rocks on the seismic properties on variable scalesâ). We observe the European Moho to be underlying the Adriatic Moho from the west up to the eastern edge of the Tauern Window. East of the Tauern Window, a sharp transition from underthrusting European to a flat and thinned crust associated with Pannonian extension tectonics occurs, which is underthrust by both European crust in the north and by Adriatic crust in the south. The Adriatic lithosphere underthrusts northward below the Southern Alps for a short distance of a few tens of km at most, and becomes steeper and deeper towards the Dinarides where it dips towards the north-east. Our results suggest that the steep high velocity region in the mantle below the Eastern Alps, observed in tomographic studies, is likely to be of European origin
Additive drug-specific and sex-specific risks associated with co-use of marijuana and tobacco during pregnancy: Evidence from 3 recent developmental cohorts (2003-2015).
BACKGROUND: Methodologic challenges related to the concomitant use (co-use) of substances and changes in policy and potency of marijuana contribute to ongoing uncertainty about risks to fetal neurodevelopment associated with prenatal marijuana use. In this study, we examined two biomarkers of fetal neurodevelopmental risk-birth weight and length of gestation-associated with prenatal marijuana use, independent of tobacco (TOB), alcohol (ALC), other drug use (OTH), and socioeconomic risk (SES), in a pooled sample (NâŻ=âŻ1191) derived from 3 recent developmental cohorts (2003-2015) with state-of-the-art substance use measures. We examined differential associations by infant sex, and multiplicative effects associated with co-use of MJ and TOB.
METHODS: Participants were mother-infant dyads with complete data on all study variables derived from Growing Up Healthy (nâŻ=âŻ251), Behavior and Mood in Babies and Mothers (Cohorts 1 and 2; nâŻ=âŻ315), and the Early Growth and Development Study (NâŻ=âŻ625). We estimated direct effects on birth weight and length of gestation associated with MJ, TOB, and co-use (MJ x TOB), using linear regression analysis in the full sample, and in male (nâŻ=âŻ654) and female (nâŻ=âŻ537) infants, separately.
RESULTS: Mean birth weight and length of gestation were 3277âŻg (SDâŻ=âŻ543) and 37.8âŻweeks (SDâŻ=âŻ2.0), respectively. Rates of prenatal use were as follows: any use, nâŻ=âŻ748 (62.8%); MJ use, nâŻ=âŻ273 (22.9%); TOB use, nâŻ=âŻ608 (51.0%); co-use of MJ and TOB, nâŻ=âŻ230 (19.3%); ALC use, nâŻ=âŻ464 (39.0%); and OTH use nâŻ=âŻ115 (9.7%.) For all infants, unique effects on birth weight were observed for any MJ use [B(SE)âŻ=âŻ-84.367(38.271), 95% C.I. -159.453 to -9.281, pâŻ=âŻ.028], any TOB use [B(SE)âŻ=âŻ-0.99.416(34.418), 95% C.I. -166.942 to -31.889, pâŻ=âŻ.004], and each cigarette/day in mean TOB use [B(SE)âŻ=âŻ-12.233(3.427), 95% C.I. -18.995 to -5.510, pâŻ\u3câŻ.001]. Additional effects of co-use on birth weight, beyond these drug-specific effects, were not supported. In analyses stratified by sex, while TOB use was associated with lower birth weight in both sexes, MJ use during pregnancy was associated with lower birth weight of male infants [B(SE)âŻ=âŻ-153.1 (54.20); 95% C.I. -259.5 to -46.7, pâŻ=âŻ.005], but not female infants [B(SE)âŻ=âŻ8.3(53.1), 95% C.I. -96.024 to 112.551, pâŻ=âŻ.876]. TOB, MJ, and their co-use were not associated with length of gestation.
CONCLUSIONS: In this sample, intrauterine co-exposure to MJ and TOB was associated with an estimated 18% reduction in birth weight not attributable to earlier delivery, exposure to ALC or OTH drugs, nor to maternal SES. We found evidence for greater susceptibility of male fetuses to any prenatal MJ exposure. Examination of dose-dependence in relationships found in this study, using continuous measures of exposure, is an important next step. Finally, we underscore the need to consider (a) the potential moderating influence of fetal sex on exposure-related neurodevelopmental risks; and (b) the importance of quantifying expressions of risk through subtle alterations, rather than dichotomous outcomes
Physical activity mediates the association between personality and biomarkers of inflammation
Objectives: The current study investigated whether personality traits and facets were associated with interleukin-6, C-reactive protein, and fibrinogen, and whether physical activity mediated the relationship between personality and biomarkers of inflammation. Methods: Personality was assessed in the Midlife Development in the United States study using the Multi-Dimensional Personality Questionnaire and Midlife Development Inventory personality scale. Data were included from 960 participants (mean age = 57.86 years, standard deviation = 11.46). Personality was assessed from 2004 to 2009. Serum levels of interleukin-6, fibrinogen, and C-reactive protein were assessed in 2005â2009 as part of the Midlife Development in the United States biomarkers subproject. Results: Lower neuroticism was associated with elevated interleukin-6, and achievement was associated with lower fibrinogen. Higher physical activity was associated with lower interleukin-6 and C-reactive protein. Mediation models suggested that physical activity mediated the associations between achievement and both interleukin-6 and C-reactive protein. Discussion: Physical activity is an important factor in the Health Behavior Model of personality and explains some of the associations between personality and inflammation. These findings contribute to the fields of aging and health by linking individual difference factors to markers of inflammation, and showing that these processes may function partially through specific behaviors, in this case physical activity
Non-commutative flux representation for loop quantum gravity
The Hilbert space of loop quantum gravity is usually described in terms of
cylindrical functionals of the gauge connection, the electric fluxes acting as
non-commuting derivation operators. It has long been believed that this
non-commutativity prevents a dual flux (or triad) representation of loop
quantum gravity to exist. We show here, instead, that such a representation can
be explicitly defined, by means of a non-commutative Fourier transform defined
on the loop gravity state space. In this dual representation, flux operators
act by *-multiplication and holonomy operators act by translation. We describe
the gauge invariant dual states and discuss their geometrical meaning. Finally,
we apply the construction to the simpler case of a U(1) gauge group and compare
the resulting flux representation with the triad representation used in loop
quantum cosmology.Comment: 12 pages, matches published versio
Personality and health: Disentangling their between-person and within-person relationship in three longitudinal studies
Personality traits and physical health both change over the life span. Theoretical models and empirical evidence suggest that these changes are related. The current study investigated the dynamic relations between personality traits and physical health at both the between-person and the within-person levels. Data were drawn from three longitudinal studies: the Veterans Affairs Normative Aging Study (NAS; N = 1,734), the Longitudinal Internet Studies for the Social Sciences (LISS; N = 13,559), and the Swedish Adoption/Twin Study of Aging (SATSA, N = 2,209). Using random intercept cross-lagged panel models (RI-CLPMs) and the continuous time (CT) models, after controlling the between-person variance, generally, evidence was found for bidirectional associations between changes in neuroticism and extraversion and changes in self-rated health and general disease level. Bidirectional associations between changes in neuroticism and change in cardiovascular diseases and central nervous system diseases were observed only when time was modeled as continuous. We also found within-person associations between changes in neuroticism and extraversion and changes in performance-based ratings of motor functioning impairment. According to the current findings, the dynamic within-person relations between personality traits and health outcomes were largely in the direction consistent with their between-person connections, although the within-person relationships were substantially smaller in strength when compared their between-person counterparts. Findings from the current study highlight the importance of distinguishing between-person and within-person effects when examining the longitudinal relationship between personality traits and health
Variability Modifies Life Satisfaction\u27s Association With Mortality Risk In Older Adults
Greater life satisfaction is associated with greater longevity, but its variability across time has not been examined relative to longevity. We investigated whether mean life satisfaction across time, variability in life satisfaction across time, and their interaction were associated with mortality over 9 years of follow-up. Participants were 4,458 Australians initially at least 50 years old. During the follow-up, 546 people died. After we adjusted for age, greater mean life satisfaction was associated with a reduction in mortality risk, and greater variability in life satisfaction was associated with an increase in mortality risk. These findings were qualified by a significant interaction such that individuals with low mean satisfaction and high variability in satisfaction had the greatest risk of mortality over the follow-up period. In combination with mean life satisfaction, variability in life satisfaction is relevant for mortality risk among older adults. Considering intraindividual variability provides additional insight into associations between psychological characteristics and health
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