Design of a horizontal neutron reflectometer for the European Spallation Source

A design study of a horizontal neutron reflectometer adapted to the general baseline of the long pulse European Spallation Source (ESS) is presented. The instrument layout comprises solutions for the neutron guide, high-resolution pulse shaping and beam bending onto a sample surface being so far unique in the field of reflectometry. The length of this instrument is roughly 55 m, enabling $\delta \lambda / \lambda$ resolutions from 0.5% to 10%. The incident beam is focussed in horizontal plane to boost measurements of sample sizes of 1*1 cm{^2} and smaller with potential beam deflection in both downward and upward direction. The range of neutron wavelengths untilized by the instrument is 2 to 7.1 (12.2, ...) {\AA}, if every (second, ...) neutron source ulse is used. Angles of incidence can be set between 0{\deg} and 9{\deg} with a total accessible q-range from 4*10^{-3} {\AA}^{-1} up to 1 {\AA}^{-1}. The instrument operates both in {\theta}/{\theta} (free liquid surfaces) and {\theta}/2{\theta} (solid/liquid, air/solid interfaces) geometry. The experimental setup will in particular enable direct studies on ultrathin films (d ~ 10 {\AA}) and buried monolayers to multilayered structures of up to 3000 {\AA} total thickness. The horizontal reflectometer will further foster investigations of hierarchical systems from nanometer to micrometer length scale, as well as their kinetics and dynamical properties, in particular under load (shear, pressure, external fields). Polarization and polarization analysis as well as the GISANS option are designed as potential modules to be implemented separately in the generic instrument layout. The instrument is highly flexible and offers a variety of different measurement modes. With respect to its mechanical components the instrument is exclusively based on current technology. Risks of failure for the chosen setup are minimum.Comment: Matched to the version submitted to Nuclear Instruments and Methods

Quantitative evaluation of polymer gel dosimeters by broadband ultrasound attenuation

Ultrasound has been examined previously as an alternative readout method for irradiated polymer gel dosimeters, with authors reporting varying dose response to ultrasound transmission measurements. In this current work we extend previous work to measure the broadband ultrasound attenuation (BUA) response of irradiated PAGAT gel dosimeters, using a novel ultrasound computed tomography system

Nucleophilicity of 4-(Alkylthio)-3-imidazoline Derived Enamines

Imidazolidine-4-thiones (ITOs) are cyclic, secondary amines that were considered as potential prebiotic organocatalysts for lightdriven α-alkylations of aldehydes by bromoacetonitrile (BAN). Recent studies showed that the initially supplied ITOs represent the pre-catalyst because they undergo S-alkylation with BAN to give 4-(alkylthio)-3-imidazolines (TIMs). Given that the same reagent mix that undergoes light-driven α-alkylations is also effective in the dark, we synthesized ten ITO- or TIM-derived enamines of aldehydes and characterized their nucleophilic reactivities by kinetic studies in acetonitrile. The experimental second-order rate constants k2 for reactions of enamines with benzhydrylium ions (reference electrophiles) were evaluated by the Mayr-Patz equation, lg k2(20 °C)=sN(N+E). The determined nucleophilicities N (and sN) reveal the reactivity profiles of these enamines under prebiotically relevant conditions as well as their potential for use in organocatalytic synthesis

A High-resolution Adaptive Moving Mesh Hydrodynamic Algorithm

An algorithm for simulating self-gravitating cosmological astrophysical fluids is presented. The advantages include a large dynamic range, parallelizability, high resolution per grid element and fast execution speed. The code is based on a finite volume flux conservative Total-Variation-Diminishing (TVD) scheme for the shock capturing hydro, and an iterative multigrid solver for the gravity. The grid is a time dependent field, whose motion is described by a generalized potential flow. Approximately constant mass per cell can be obtained, providing all the advantages of a Lagrangian scheme. The grid deformation combined with appropriate limiting and smoothing schemes guarantees a regular and well behaved grid geometry, where nearest neighbor relationships remain constant. The full hydrodynamic fluid equations are implemented in the curvilinear moving grid, allowing for arbitrary fluid flow relative to the grid geometry. This combination retains all the advantages of the grid based schemes including high speed per fluid element and a rapid gravity solver. The current implementation is described, and empirical simulation results are presented. Accurate execution speed calculations are given in terms of floating point operations per time step per grid cell. This code is freely available to the community.Comment: 53 pages including 14 figures, submitted to ApJ

Scaling Behavior of Human Locomotor Activity Amplitude: Association with Bipolar Disorder

Scale invariance is a feature of complex biological systems, and abnormality of multi-scale behaviour may serve as an indicator of pathology. The hypothalamic suprachiasmatic nucleus (SCN) is a major node in central neural networks responsible for regulating multi-scale behaviour in measures of human locomotor activity. SCN also is implicated in the pathophysiology of bipolar disorder (BD) or manic-depressive illness, a severe, episodic disorder of mood, cognition and behaviour. Here, we investigated scaling behaviour in actigraphically recorded human motility data for potential indicators of BD, particularly its manic phase. A proposed index of scaling behaviour (Vulnerability Index [VI]) derived from such data distinguished between: [i] healthy subjects at high versus low risk of mood disorders; [ii] currently clinically stable BD patients versus matched controls; and [iii] among clinical states in BD patients

Iron biogeochemistry across marine systems progress from the past decade

Based on an international workshop (Gothenburg, 14–16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas

Lixiviação de nitrogênio em um Cambissolo cultivado com pessegueiro e submetido à aplicação de composto orgânico.

A aplicação de composto orgânico em solos cultivados com pessegueiro pode potencializar a transferência de N por lixiviação. O trabalho objetivou avaliar a lixiviação de N em um solo cultivado com pessegueiro e submetido à aplicação de composto orgânico. Em um pomar comercial de pessegueiro no município de Bento Gonçalves (RS) foram instalados lisímetros a 20 cm de profundidade. O solo recebeu a aplicação de 0 e 144 litros de composto orgânico por planta-1 ano-1 nas safras de 2010, 2011 e 2012. A solução do solo foi coletada no período de julho a outubro de 2012 e submetida à análise de nitrato, amônio e N mineral. As maiores concentrações de N lixiviado foram encontradas no tratamento com 144 litros de composto orgânico por planta-1. A adubação com composto orgânico apresentou baixas concentrações de N lixiviado, o que pode contribuir com a redução de contaminação ambiental.Resumo expandido

Ground Vibrational State SiO Emission in the VLA BAaDE Survey

Using a subsample of the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey of stellar SiO masers, we explore the prevalence and characteristics of $^{28}$SiO $J=1-0, v=0$ emission. We identify 90 detections of maser, thermal, or composite $^{28}$SiO $J=1-0, v=0$ emission out of approximately 13,000 candidate spectra from the NSF's Karl G. Jansky Very Large Array (VLA). We find that the detected sources are likely asymptotic giant branch (AGB) stars belonging to a bright, foreground Milky Way stellar disk population. For the 32 sources showing thermal components, we extract values for outflow velocity by fitting thermal line profiles. We find a range of circumstellar envelope expansion velocities, and compare to previously recorded OH and CO expansion velocities. This preliminary survey is already the largest study of stellar ground-vibrational-state SiO masers to date, and will be expanded to include the entire VLA BAaDE dataset when data reduction for the 18,988 target sources is completed.Comment: 23 pages, 8 figures, to be published in The Astronomical Journa

Evaluation of an entraining droplet activation parameterization using in situ cloud data

This study investigates the ability of a droplet activation parameterization (which considers the effects of entrainment and mixing) to reproduce observed cloud droplet number concentration (CDNC) in ambient clouds. Predictions of the parameterization are compared against cloud averages of CDNC from ambient cumulus and stratocumulus clouds sampled during CRYSTAL‐FACE (Key West, Florida, July 2002) and CSTRIPE (Monterey, California, July 2003), respectively. The entrainment parameters required by the parameterization are derived from the observed liquid water content profiles. For the cumulus clouds considered in the study, CDNC is overpredicted by 45% with the adiabatic parameterization. When entrainment is accounted for, the predicted CDNC agrees within 3.5%. Cloud‐averaged CDNC for stratocumulus clouds is well captured when entrainment is not considered. In all cases considered, the entraining parameterization compared favorably against a statistical correlation developed from observations to treat entrainment effects on droplet number. These results suggest that including entrainment effects in the calculation of CDNC, as presented here, could address important overprediction biases associated with using adiabatic CDNC to represent cloud‐scale average values

Sheep research and development, 1965

Sheep research and development - 1965 / D. S. Bell -- Improvement of lamb meat production through breeding / D. S. Bell, C. F. Parker and L. E. Kunkle -- Breeding performance of Targhee ewes maintained under bluegrass pasture vs. ladino clover pasture vs. barn confinement management / D. S. Bell and C. F. Parker -- Ram effect on ewe fertility / C. F. Parker and D. S. Bell -- Creep feeding native lambs / J. K. Judy, J. H. Cline, W. J. Tyznik, C. F. Parker and D. S. Bell -- Studies of the protein and energy requirements of growing-finishing lambs / R. R. Johnson, J. H. Cline and D. S. Bell -- Visual and ultrasonic evaluation of creep fed slaughter lambs / C. F. Parker, D. L. Davis and J. K. Judy -- Forages for summer feeding of farm flocks / R. W. Van Keuren -- Characteristics of consumer-preferred lamb carcass / L. E. Kunkl