1,780 research outputs found
The effect of direct drilling and soil type on soil atmosphere composition
A study of the soil atmosphere in soils ploughed and cultivated normally and under long-term direct drilling was made in two soil types throughout a two year period, 1973 to 1975. Probes were sited at two depths, 15 cm and 30 cm, in the two cultivation treatments, mou\board ploughing to a depth of 20 cm and no-tillage, and in plots with different soil types, a sandy loam (Macmerry series) and a sandy clay loam (W'inton series). Spring barley (cv Zephyr) was grown every year.Soil atmosphere samples were withdrawn at weekly intervals and analysed by gas chromatography for carbon dioxide, oxygen, methane and ethylene.The sites were sampled for moisture content, bulk density and temperature to aid the interpretation of the results.In the first growing season the soil atmosphere had a higher carbon dioxide and lower oxygen percentage than in the second, this being related to a higher rainfall and temperature in the first season. Soil atmosphere composition was similar in the two winters. The methane component of the soil atmosphere declined throughout each growing season as soil moisture declined but levels were found to be higher in 1974- than 1973.Ethylene was not detected regularly and not in any appreciable quantity. There was a greater incidence of detection from probes sited in no-tillage plots at a depth of 30 cm. Oxygen levels, as sampled, have little influence on ethylene in the soil atmosphere.In a comparison between the treatments, no-tillage and ploughing, the carbon dioxide percentage of the soil atmosphere was always higher and the oxygen percentage lower, in the first growing season only, under no-tillage. This was related to a markedly lower air filled porosity in this treatment. Similarly in the first growing season differences in the soil atmosphere between soil types were seen with a higher carbon dioxide and lower oxygen percentage in the Winton soil. This soil was consistently lower in air filled porosity but only at the low levels found in the first, wetter, growing season was this difference reflected in the composition of the soil atmosphere. The soil atmosphere at 30 cm was higher in carbon dioxide and lover in oxygen than the soil atmosphere at 15 cm.The soil was also sampled at monthly intervals for one year and incubated anaerobically in the laboratory. This showed that throughout the year the soil did have the capacity to produce ethylene.PTFE tubing as a soil atmosphere sampling tool was investigated and shown to be successful
Working with Children with Learning Disabilities and/or who Communicate Non-verbally: Research experiences and their implications for social work education, increased participation and social inclusion
Social exclusion, although much debated in the UK, frequently focuses on children as a key 'at risk' group. However, some groups, such as disabled children, receive less consideration. Similarly, despite both UK and international policy and guidance encouraging the involvement of disabled children and their right to participate in decision-making arenas, they are frequently denied this right. UK based evidence suggests that disabled children's participation lags behind that of their non-disabled peers, often due to social work practitioners' lack of skills, expertise and knowledge on how to facilitate participation. The exclusion of disabled children from decision-making in social care processes echoes their exclusion from participation in society. This paper seeks to begin to address this situation, and to provide some examples of tools that social work educators can introduce into pre- and post-qualifying training programmes, as well as in-service training. The paper draws on the experiences of researchers using non-traditional qualitative research methods, especially non-verbal methods, and describes two research projects, focusing on the methods employed to communicate with and involve disabled children, the barriers encountered and lessons learnt. Some of the ways in which these methods of communication can inform social work education are explored alongside wider issues of how and if increased communication can facilitate greater social inclusion
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Fabrication of large-volume, low-cost ceramic lanthanum halide scintillators for gamma ray detection : final report for DHS/DNDO/TRDD project TA-01-SL01.
This project uses advanced ceramic processes to fabricate large, optical-quality, polycrystalline lanthanum halide scintillators to replace small single crystals produced by the conventional Bridgman growth method. The new approach not only removes the size constraint imposed by the growth method, but also offers the potential advantages of both reducing manufacturing cost and increasing production rate. The project goal is to fabricate dense lanthanum halide ceramics with a preferred crystal orientation by applying texture engineering and solid-state conversion to reduce the thermal mechanical stress in the ceramic and minimize scintillation light scattering at grain boundaries. Ultimately, this method could deliver the sought-after high sensitivity and <3% energy resolution at 662 keV of lanthanum halide scintillators and unleash their full potential for advanced gamma ray detection, enabling rapid identification of radioactive materials in a variety of practical applications. This report documents processing details from powder synthesis, seed particle growth, to final densification and texture development of cerium doped lanthanum bromide (LaBr{sub 3}:Ce{sup +3}) ceramics. This investigation demonstrated that: (1) A rapid, flexible, cost efficient synthesis method of anhydrous lanthanum halides and their solid solutions was developed. Several batches of ultrafine LaBr{sub 3}:Ce{sup +3} powder, free of oxyhalide, were produced by a rigorously controlled process. (2) Micron size ({approx} 5 {micro}m), platelet shape LaBr{sub 3} seed particles of high purity can be synthesized by a vapor phase transport process. (3) High aspect-ratio seed particles can be effectively aligned in the shear direction in the ceramic matrix, using a rotational shear-forming process. (4) Small size, highly translucent LaBr{sub 3} (0.25-inch diameter, 0.08-inch thick) samples were successfully fabricated by the equal channel angular consolidation process. (5) Large size, high density, translucent LaBr{sub 3} ceramics samples (3-inch diameter, > 1/8-inch thick) were fabricated by hot pressing, demonstrating the superior manufacturability of the ceramic approach over single crystal growth methods in terms of size capability and cost. (6) Despite all these advances, evidence has shown that LaBr{sub 3} is thermally unstable at temperatures required for the densification process. This is particularly true for material near the surface where lattice defects and color centers can be created as bromine becomes volatile at high temperatures. Consequently, after densification these samples made using chemically prepared ultrafine powders turned black. An additional thermal treatment in a flowing bromine condition proved able to reduce the darkness of the surface layer for these densified samples. These observations demonstrated that although finer ceramic powders are desirable for densification due to a stronger driving force from their large surface areas, the same desirable factor can lead to lattice defects and color centers when these powders are densified at higher temperatures where material near the surface becomes thermally unstable
Defining the proteolytic landscape during enterovirus infection.
Viruses cleave cellular proteins to remodel the host proteome. The study of these cleavages has revealed mechanisms of immune evasion, resource exploitation, and pathogenesis. However, the full extent of virus-induced proteolysis in infected cells is unknown, mainly because until recently the technology for a global view of proteolysis within cells was lacking. Here, we report the first comprehensive catalog of proteins cleaved upon enterovirus infection and identify the sites within proteins where the cleavages occur. We employed multiple strategies to confirm protein cleavages and assigned them to one of the two enteroviral proteases. Detailed characterization of one substrate, LSM14A, a p body protein with a role in antiviral immunity, showed that cleavage of this protein disrupts its antiviral function. This study yields a new depth of information about the host interface with a group of viruses that are both important biological tools and significant agents of disease
Identifying Star Streams in the Milky Way Halo
We develop statistical methods for identifying star streams in the halo of
the Milky Way galaxy that exploit observed spatial and radial velocity
distributions. Within a great circle, departures of the observed spatial
distribution from random provide a measure of the likelihood of a potential
star stream. Comparisons between the radial velocity distribution within a
great circle and the radial velocity distribution of the entire sample also
measure the statistical significance of potential streams. The radial
velocities enable construction of a more powerful joint statistical test for
identifying star streams in the Milky Way halo. Applying our method to halo
stars in the Hypervelocity Star (HVS) survey, we detect the Sagittarius stream
at high significance. Great circle counts and comparisons with theoretical
models suggest that the Sagittarius stream comprises 10% to 17% of the halo
stars in the HVS sample. The population of blue stragglers and blue horizontal
branch stars varies along the stream and is a potential probe of the
distribution of stellar populations in the Sagittarius dwarf galaxy prior to
disruption.Comment: 10 pages, 10 figures, submitted to Ap
The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). V. The Structure of M33 in Resolved Stellar Populations
We present a detailed analysis of the the structure of the Local Group
flocculent spiral galaxy M33, as measured using the Panchromatic Hubble
Andromeda Treasury Triangulum Extended Region (PHATTER) survey. Leveraging the
multiwavelength coverage of PHATTER, we find that the oldest populations are
dominated by a smooth exponential disk with two distinct spiral arms and a
classical central bar completely distinct from what is seen in broadband
optical imaging, and the first-ever confirmation of a bar in M33. We estimate a
bar extent of 1 kpc. The two spiral arms are asymmetric in orientation
and strength, and likely represent the innermost impact of the recent tidal
interaction responsible for M33's warp at larger scales. The flocculent
multi-armed morphology for which M33 is known is only visible in the young
upper main sequence population, which closely tracks the morphology of the ISM.
We investigate the stability of M33's disk, finding over the
majority of the disk. We fit multiple components to the old stellar density
distribution and find that, when considering recent stellar kinematics, M33's
bulk structure favors the inclusion of an accreted halo component, modeled as a
broken power-law. The best-fit halo model has an outer power-law index of 3
and accurately describes observational evidence of M33's stellar halo from both
resolved stellar spectroscopy in the disk and its stellar populations at large
radius. Integrating this profile yields a total halo stellar mass of
, giving a total stellar halo mass fraction of
16%, most of which resides in the innermost 2.5 kpc.Comment: 31 pages, 17 figures, 5 tables, Accepted for publication in Ap
Infall Regions of Galaxy Clusters
In hierarchical clustering, galaxy clusters accrete mass through the
aggregation of smaller systems. Thus, the velocity field of the infall regions
of clusters contains significant random motion superimposed on radial infall.
Because the purely spherical infall model does not predict the amplitude of the
velocity field correctly, methods estimating the cosmological density parameter
Omega_0 based on this model yield unreliable biased results. In fact, the
amplitude of the velocity field depends on local dynamics and only very weakly
on the global properties of the universe. We use N-body simulations of flat and
open universes to show that the amplitude of the velocity field of the infall
regions of dark matter halos is a direct measure of the escape velocity within
these regions. We can use this amplitude to estimate the mass of dark matter
halos within a few megaparsecs from the halo center. In this region dynamical
equilibrium assumptions do not hold. The method yields a mass estimate with
better than 30% accuracy. If galaxies trace the velocity field of the infall
regions of clusters reliably, this method provides a straightforward way to
estimate the amount of mass surrounding rich galaxy clusters from redshift data
alone.Comment: 26 pages, AAS Latex macros v4.0, to appear in The Astrophysical
Journal, June 1, 1997 issue, Vol. 48
Vitamin K supplementation to improve vascular stiffness in CKD:The K4Kidneys randomized controlled trial
BACKGROUND:Vascular calcification, a risk factor for cardiovascular disease, is common among patients with CKD and is an independent contributor to increased vascular stiffness and vascular risk in this patient group. Vitamin K is a cofactor for proteins involved in prevention of vascular calcification. Whether or not vitamin K supplementation could improve arterial stiffness in patients with CKD is unknown. METHODS:To determine if vitamin K supplementation might improve arterial stiffness in patients in CKD, we conducted a parallel-group, double-blind, randomized trial in participants aged 18 or older with CKD stage 3b or 4 (eGFR 15-45 ml/min per 1.73 m2). We randomly assigned participants to receive 400 μg oral vitamin K2 or matching placebo once daily for a year. The primary outcome was the adjusted between-group difference in carotid-femoral pulse wave velocity at 12 months. Secondary outcomes included augmentation index, abdominal aortic calcification, BP, physical function, and blood markers of mineral metabolism and vascular health. We also updated a recently published meta-analysis of trials to include the findings of this study. RESULTS:We included 159 randomized participants in the modified intention-to-treat analysis, with 80 allocated to receive vitamin K and 79 to receive placebo. Mean age was 66 years, 62 (39%) were female, and 87 (55%) had CKD stage 4. We found no differences in pulse wave velocity at 12 months, augmentation index at 12 months, BP, B-type natriuretic peptide, or physical function. The updated meta-analysis showed no effect of vitamin K supplementation on vascular stiffness or vascular calcification measures. CONCLUSIONS:Vitamin K2 supplementation did not improve vascular stiffness or other measures of vascular health in this trial involving individuals with CKD. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER:Vitamin K therapy to improve vascular health in patients with chronic kidney disease, ISRCTN21444964 (www.isrctn.com)
Runx1 deficiency protects against adverse cardiac remodeling following myocardial infarction
Background: Myocardial infarction (MI) is a leading cause of heart failure and death worldwide. Preservation of contractile function and protection against adverse changes in ventricular architecture (cardiac remodeling) are key factors to limiting progression of this condition to heart failure. Consequently, new therapeutic targets are urgently required to achieve this aim. Expression of the Runx1 transcription factor is increased in adult cardiomyocytes after MI; however, the functional role of Runx1 in the heart is unknown.
Methods: To address this question, we have generated a novel tamoxifen-inducible cardiomyocyte-specific Runx1-deficient mouse. Mice were subjected to MI by means of coronary artery ligation. Cardiac remodeling and contractile function were assessed extensively at the whole-heart, cardiomyocyte, and molecular levels.
Results: Runx1-deficient mice were protected against adverse cardiac remodeling after MI, maintaining ventricular wall thickness and contractile function. Furthermore, these mice lacked eccentric hypertrophy, and their cardiomyocytes exhibited markedly improved calcium handling. At the mechanistic level, these effects were achieved through increased phosphorylation of phospholamban by protein kinase A and relief of sarco/endoplasmic reticulum Ca2+-ATPase inhibition. Enhanced sarco/endoplasmic reticulum Ca2+-ATPase activity in Runx1-deficient mice increased sarcoplasmic reticulum calcium content and sarcoplasmic reticulum–mediated calcium release, preserving cardiomyocyte contraction after MI.
Conclusions: Our data identified Runx1 as a novel therapeutic target with translational potential to counteract the effects of adverse cardiac remodeling, thereby improving survival and quality of life among patients with MI
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