1,615 research outputs found
Comparing Trace Elements (As, Cu, Ni, Pb, and Zn) in Soils and Surface Waters among Montane, Upland Watersheds and Lowland, Urban Watersheds in New England, USA
Trace element biogeochemistry from soils to rivers is important for toxicity to aquatic ecosystems. The objective of this study was to determine whether trace element exports in contrasting watersheds are controlled by their abundance in soil, current land uses in the watershed, or geologic processes. Upland soils and river water samples were collected throughout the Deerfield watershed in southern Vermont and western Massachusetts and in the Quinebaug and Shetucket watersheds of eastern Connecticut. Soil concentrations were only an important predictor for dissolved Fe export, but no other trace element. Soil pH was not correlated with normalized dissolved exports of trace elements, but DOC was correlated with normalized dissolved Pb and Ni exports. The limited spatial and depth of soil sampling may have contributed to the poor correlation. Surprisingly, linear regressions and principal component analysis showed that human development was associated with higher soil trace metal concentrations but not significantly correlated with dissolved trace elements export. Instead, forest abundance was a strong predictor for lower Cu, Pb, and Zn soil concentrations and lower As, Fe, Ni and Pb dissolved exports across the watersheds. Dissolved exports of Al, K, and Si suggest that enhanced mineral dissolution in the montane watersheds was likely an important factor for matching or exceeding normalized pollutant trace element exports in more urbanized watersheds. Further studies are needed to evaluate subsurface/hyporheic controls as well as soil–surface water interface to quantify exchange and transport
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Transfer of Macronutrients, Micronutrients, and Toxic Elements from Soil to Grapes to White Wines in Uncontaminated Vineyards
Wine is a popular beverage and may be a source of nutrient and toxic elements during human consumption. Here, we explored the variation in nutrient and toxic elements from soils to grape berries and commercial white wines (Chardonnay) at five USA vineyards (New York, Vermont, California, Virginia) with strongly contrasting geology, soils, and climates. Samples were analyzed for macronutrients (Ca, K, and Mg), micronutrients (Mn, Cu, and Zn), and toxic elements (As, Cd, and Pb). Our study showed contrasting macronutrient, micronutrient, and toxic element concentrations in soils and in vines, leaves, and grapes. However, plant tissue concentrations did not correspond with total soil concentrations, suggesting a disconnect governing their accumulation. Bioconcentration factors for soil to grape berry transfer suggest the accumulation of Ca, K and Mg in berries while Fe, Mn, Cu, Zn, and Pb were generally not accumulated in our study or in previous studies. Wines from the five vineyards studied had comparable nutrient, micronutrient, and toxic metal concentrations as wines from Germany, Italy, Portugal, Spain, Croatia, Czech Republic, and Japan. The transfer of nutrients and toxic elements from grape berries to wine indicated that only Ca, K, and Mg were added or retained while concentrations of all other micronutrients and toxic elements were somewhat to extensively diminished. Thus, there appears to be a substantial effect on the geochemistry of the wine from the grape from either the fermentation process (i.e., flocculation), or a dilution effect. We conclude that soils, geology, and climate do not appear to generate a unique geochemical terroir as the transfer and concentration of inorganic nutrients appear to be comparable across strongly contrasting vineyards. This has several implications for human health. Nutrients in wine have potential impacts for human nutrition, as wine can meet or exceed the recommended dietary requirements of Ca, K, Mg, and Fe, and toxic metals As and Pb concentrations were also non-trivial
Looking ‘Acceptably’ Feminine:A Single Case Study of a Female Bodybuilder’s Use of Steroids
This article aims to shed some light on the motivations for and methods of female steroid consumption apropos broader changes in female body image ideals. Moreover, the study attempts to explore the connections between the competitive logic of liberal-postmodern consumer capitalism, ‘competitive femininity’ and steroid use. There is a growing consensus that an increasing number of women are consuming steroids, yet this phenomenon remains relatively under-researched and as such not much is known about this particular group of users. Utilising a single in-depth case study, this paper offers some additional insight gleaned from an ethnographic interview with a female bodybuilder who uses steroids. Her narrative elucidates some of the risks, harms and motivations for steroid consumption alongside broader changes in female body image ideals. Among the central findings, this paper highlights that the female bodybuilder is not resisting cultural norms but rather hyper-conforming to them by over-identifying with a hyper-idealised form of what constitutes ‘acceptable femininity’. We conclude that steroid consumption retains a strong connection to the desire for aesthetic appeal and that both short and long-term motivations for using steroids are grounded in the drive for conformity. This has pertinent clinical implications for health professionals, particularly in relation to the efficacy of attempts to reduce steroid consumption by warning users of the potential adverse health effects
Getting big but not hard: A retrospective case-study of a male powerlifter's experience of steroid-induced erectile dysfunction
This article aims to excavate the lived experience of suffering with steroid-induced erectile dysfunction. By drawing upon original qualitative data, we chart the subjective journey to recovery of a male powerlifter and draw attention to the potential dangers of a self-help approach to treatment. Erectile dysfunction is a common symptom of anabolic-androgenic steroid-induced hypogonadism, a condition not commonly reported or discussed and is therefore a poorly studied health issue. Often considered a taboo subject, detailed accounts of men's experience of erectile dysfunction are relatively sparce, and so this paper makes an important contribution to bolstering what is a limited literature base. Links between contemporary conceptions of masculinity, muscularity, and sexual prowess are explored and form the basis of a critical analysis of popular treatment and prevention strategies. Among the central findings, this article suggests that steroids are not consumed despite the well-known risks, but precisely because the risks are well-known and ostensibly mitigated through engagement with ‘bro-science’. We conclude that there is a concerning misalignment in current treatment and prevention strategies that needs to be addressed if the issue of non-prescribed steroid use is to be effectively tackled. This research therefore raises serious questions for the healthcare profession and its approach towards treating and preventing steroid consumption
Multi-Instantons and Exact Results II: Specific Cases, Higher-Order Effects, and Numerical Calculations
In this second part of the treatment of instantons in quantum mechanics, the
focus is on specific calculations related to a number of quantum mechanical
potentials with degenerate minima. We calculate the leading multi-instanton
constributions to the partition function, using the formalism introduced in the
first part of the treatise [J. Zinn-Justin and U. D. Jentschura, e-print
quant-ph/0501136]. The following potentials are considered: (i) asymmetric
potentials with degenerate minima, (ii) the periodic cosine potential, (iii)
anharmonic oscillators with radial symmetry, and (iv) a specific potential
which bears an analogy with the Fokker-Planck equation. The latter potential
has the peculiar property that the perturbation series for the ground-state
energy vanishes to all orders and is thus formally convergent (the ground-state
energy, however, is nonzero and positive). For the potentials (ii), (iii), and
(iv), we calculate the perturbative B-function as well as the instanton
A-function to fourth order in g. We also consider the double-well potential in
detail, and present some higher-order analytic as well as numerical
calculations to verify explicitly the related conjectures up to the order of
three instantons. Strategies analogous to those outlined here could result in
new conjectures for problems where our present understanding is more limited.Comment: 55 pages, LaTeX; refs. to part I preprint update
Regolith Weathering and Sorption Influences Molybdenum, Vanadium, and Chromium Export via Stream Water at Four Granitoid Critical Zone Observatories
Understanding the fate of oxyanions in the Critical Zone is important because of their biological significance and the potential for their use as geochemical tracers in terrestrial environments and subsurface systems. This study assessed the partitioning and transport of a suite of oxyanion metals (Mo, V, and Cr) in regolith profiles and stream waters from four granitoid Critical Zone Observatories (CZOs) (Boulder Creek, Calhoun, Luquillo, and Southern Sierra). For regolith profiles, we compared Mo, V, and Cr in total digestions and two extractions targeting oxyanions adsorbed to organic matter and amorphous oxides (H2O2 + 0.1 M acetic acid) and secondary Fe oxides (citrate–bicarbonate–dithionite). Total Mo, V, and Cr ranged from 0.4 to 2.5 mg kg-1, 16 to 208 mg kg-1, and 0.2 to 55 mg kg-1, respectively. The greatest concentrations of the oxyanions did not occur in surface soil samples, nor deepest regolith samples (7–10 m in depth), but instead in subsurface peaks that corresponded with secondary Fe oxides and total organic carbon. The average organic and amorphous oxide bound phase was 0.1–3.5% while the secondary Fe oxide fraction was 4–27% of the respective total concentrations for oxyanions, suggesting that secondary Fe oxides were an important phase across the regolith profile. Stream water Mo, V, and Cr concentrations ranged from 0.02 to 0.25 μg L-1, 0.2 to 1.8 μg L-1, and 0.08 to 0.44 μg L-1, respectively. Our results demonstrate that the deep regolith (2–7 m in depth) play an active role in both sourcing and retention of oxyanions. In addition, we observed that increased weathering intensity at warmer, wetter climates does not always lead to increased depletion in regolith or stream water export, which implies the importance of transport processes within regolith. Further quantification of oxyanion export from regolith can aid in developing their use as geochemical tools for global weathering
Characterization of Singlet Ground and Low-Lying Electronic Excited States of Phosphaethyne and Isophosphaethyne
The singlet ground _X˜ 1_+_ and excited _1_− , 1__ states of HCP and HPC have been systematically investigated using ab initio molecular electronic structure theory. For the ground state, geometries of the two linear stationary points have been optimized and physical properties have been predicted utilizing restricted self-consistent field theory, coupled cluster theory with single and double excitations _CCSD_, CCSD with perturbative triple corrections _CCSD_T__, and CCSD with partial iterative triple excitations _CCSDT-3 and CC3_. Physical properties computed for the global minimum _X˜ 1_+HCP_ include harmonic vibrational frequencies with the cc-pV5Z CCSD_T_ method of _1=3344 cm−1, _2=689 cm−1, and _3=1298 cm−1. Linear HPC, a stationary point of Hessian index 2, is predicted to lie 75.2 kcal mol−1 above the global minimum HCP. The dissociation energy D0_HCP_X˜ 1_+_→H_2S_+CP_X 2_+__ of HCP is predicted to be 119.0 kcal mol−1, which is very close to the experimental lower limit of 119.1 kcal mol−1. Eight singlet excited states were examined and their physical properties were determined employing three equation-of-motion coupled cluster methods _EOM-CCSD, EOM-CCSDT-3, and EOM-CC3_. Four stationary points were located on the lowest-lying excited state potential energy surface, 1_− →1A_, with excitation energies Te of 101.4 kcal mol−1_1A_ HCP_, 104.6 kcal mol−1_1_− HCP_, 122.3 kcal mol−1_1A_ HPC_, and 171.6 kcal mol−1_1_− HPC_ at the cc-pVQZ EOM-CCSDT-3 level of theory. The physical properties of the 1A_ state with a predicted bond angle of 129.5° compare well with the experimentally reported first singlet state _A˜ 1A__. The excitation energy predicted for this excitation is T0=99.4 kcal mol−1_34 800 cm−1 , 4.31 eV_, in essentially perfect agreement with the experimental value of T0=99.3 kcal mol−1_34 746 cm−1 ,4.308 eV_. For the second lowest-lying excited singlet surface, 1_→1A_, four stationary points were found with Te values of 111.2 kcal mol−1 _21A_ HCP_, 112.4 kcal mol−1 _1_ HPC_, 125.6 kcal mol−1_2 1A_ HCP_, and 177.8 kcal mol−1_1_ HPC_. The predicted CP bond length and frequencies of the 2 1A_ state with a bond angle of 89.8° _1.707 Å, 666 and 979 cm−1_ compare reasonably well with those for the experimentally reported C ˜ 1A_ state _1.69 Å, 615 and 969 cm−1_. However, the excitation energy and bond angle do not agree well: theoretical values of 108.7 kcal mol−1 and 89.8° versus experimental values of 115.1 kcal mol−1 and 113°
Higher-Order Corrections to Instantons
The energy levels of the double-well potential receive, beyond perturbation
theory, contributions which are non-analytic in the coupling strength; these
are related to instanton effects. For example, the separation between the
energies of odd- and even-parity states is given at leading order by the
one-instanton contribution. However to determine the energies more accurately
multi-instanton configurations have also to be taken into account. We
investigate here the two-instanton contributions. First we calculate
analytically higher-order corrections to multi-instanton effects. We then
verify that the difference betweeen numerically determined energy eigenvalues,
and the generalized Borel sum of the perturbation series can be described to
very high accuracy by two-instanton contributions. We also calculate
higher-order corrections to the leading factorial growth of the perturbative
coefficients and show that these are consistent with analytic results for the
two-instanton effect and with exact data for the first 200 perturbative
coefficients.Comment: 7 pages, LaTe
Time resolved single photon imaging in Nanometer Scale CMOS technology
Time resolved imaging is concerned with the measurement of photon arrival
time. It has a wealth of emerging applications including biomedical uses such as
fluorescence lifetime microscopy and positron emission tomography, as well as laser
ranging and imaging in three dimensions. The impact of time resolved imaging on
human life is significant: it can be used to identify cancerous cells in-vivo, how well
new drugs may perform, or to guide a robot around a factory or hospital.
Two essential building blocks of a time resolved imaging system are a photon
detector capable of sensing single photons, and fast time resolvers that can measure
the time of flight of light to picosecond resolution. In order to address these emerging
applications, miniaturised, single-chip, integrated arrays of photon detectors and time
resolvers must be developed with state of the art performance and low cost. The goal
of this research is therefore the design, layout and verification of arrays of low noise
Single Photon Avalanche Diodes (SPADs) together with high resolution Time-Digital
Converters (TDCs) using an advanced silicon fabrication process.
The research reported in this Thesis was carried out as part of the E.U. funded
Megaframe FP6 Project. A 32x32 pixel, one million frames per second, time
correlated imaging device has been designed, simulated and fabricated using a 130nm
CMOS Imaging process from ST Microelectronics. The imager array has been
implemented together with required support cells in order to transmit data off chip at
high speed as well as providing a means of device control, test and calibration. The
fabricated imaging device successfully demonstrates the research objectives.
The Thesis presents details of design, simulation and characterisation results
of the elements of the Megaframe device which were the author’s own work.
Highlights of the results include the smallest and lowest noise SPAD devices yet
published for this class of fabrication process and an imaging array capable of
recording single photon arrivals every microsecond, with a minimum time resolution
of fifty picoseconds and single bit linearity
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