150 research outputs found
Potentiometric Titration of Sulfate in Water and Soil Extracts Using a Lead-Mercury Amalgam Indicator Electrode
Sulfate concentrations in pure solutions, drainage waters,
and soil saturation extracts were determined potentiometrically
using a 70% Pb and 30% Hg amalgam indicator electrode and
a saturated calomel reference electrode. Adjusting all samples
to pH 4.7 allowed titration to a fixed potential on an automatic
titrator. Sulfate concentrations ranging from 0.2 to 10 mmole/
liter were determined by this method and compared with
concentration determined by a turbidimetric method. Results
from the two methods did not differ significantly, but the potentiometric
titration method was more precise, sensitive, and
rapid
The teenage religion and values survey in England and Wales : an overview
The Teenage Religion and Values Survey was conducted throughout the 1990s among young people between the ages of 13 and 15 years. A total of 33,982 young people took part in the survey. As the next phase of this research begins for the twenty-first century this paper looks back at the survey conducted in the 1990s and considers two aspects of the research. First, this paper considers the methodology behind designing such a survey. Second, this paper considers some of the insights generated by the survey under five headings: personality, spiritual health, religious affiliation, belonging without believing, and church leaving
Genome-wide association study of peripheral neuropathy with D-drug-containing regimens in AIDS Clinical Trials Group protocol 384.
Stavudine (d4T) was, until recently, one of the most widely prescribed antiretroviral drugs worldwide. While there has been a major shift away from d4T use in resource-limited countries, a large number of patients have previously received (or continue to receive) d4T, and many have developed peripheral neuropathy. The identification of genetic predictors of increased risk might suggest novel therapeutic targets for such patients. In AIDS Clinical Trials Group protocol 384, antiretroviral-naĂŻve patients were randomized to d4T/didanosine (ddI)- or zidovudine/lamivudine-containing regimens. Data from d4T/ddI recipients were analyzed for genome-wide associations (approximately 1 million genetic loci) with new onset distal sensory peripheral neuropathy. Analyses involved 254 patients (49 % White, 34 % Black, 17 % Hispanic), comprising 90 peripheral neuropathy cases (32 grade 1, 35 grade 2, 23 grade 3) and 164 controls. After correcting for multiple comparisons, no polymorphism was consistently associated with neuropathy among all patients, among White, Black, and Hispanic patients analyzed separately, both in genome-wide analyses (threshold, Pâ<â5.0âĂâ10(-8)) and focused on 46 neuropathy-associated genes (threshold, Pâ<â3.5âĂâ10(-5)). In the latter analyses, the lowest P values were in KIF1A among Whites (rs10199388, Pâ=â8.4âĂâ10(-4)), in LITAF among Blacks (rs13333308, Pâ=â6.0âĂâ10(-6)), and in NEFL among Hispanics (rs17763685, Pâ=â5.6âĂâ10(-6)). Susceptibility to d4T/ddI-associated neuropathy is not explained by a single genetic variant with a marked effect
A Matrix Model for the Null-Brane
The null-brane background is a simple smooth 1/2 BPS solution of string
theory. By tuning a parameter, this background develops a big crunch/big bang
type singularity. We construct the DLCQ description of this space-time in terms
of a Yang-Mills theory on a time-dependent space-time. Our dual Matrix
description provides a non-perturbative framework in which the fate of both
(null) time, and the string S-matrix can be studied.Comment: 26 pages, LaTeX; references adde
Generation of defects and disorder from deeply quenching a liquid to form a solid
We show how deeply quenching a liquid to temperatures where it is linearly
unstable and the crystal is the equilibrium phase often produces crystalline
structures with defects and disorder. As the solid phase advances into the
liquid phase, the modulations in the density distribution created behind the
advancing solidification front do not necessarily have a wavelength that is the
same as the equilibrium crystal lattice spacing. This is because in a deep
enough quench the front propagation is governed by linear processes, but the
crystal lattice spacing is determined by nonlinear terms. The wavelength
mismatch can result in significant disorder behind the front that may or may
not persist in the latter stage dynamics. We support these observations by
presenting results from dynamical density functional theory calculations for
simple one- and two-component two-dimensional systems of soft core particles.Comment: 25 pages, 11 figure
Parameters of the Magnetic Flux inside Coronal Holes
Parameters of magnetic flux distribution inside low-latitude coronal holes
(CHs) were analyzed. A statistical study of 44 CHs based on Solar and
Heliospheric Observatory (SOHO)/MDI full disk magnetograms and SOHO/EIT 284\AA
images showed that the density of the net magnetic flux, , does
not correlate with the associated solar wind speeds, . Both the area and
net flux of CHs correlate with the solar wind speed and the corresponding
spatial Pearson correlation coefficients are 0.75 and 0.71, respectively. A
possible explanation for the low correlation between and
is proposed. The observed non-correlation might be rooted in the structural
complexity of the magnetic field. As a measure of complexity of the magnetic
field, the filling factor, , was calculated as a function of spatial
scales. In CHs, was found to be nearly constant at scales above 2 Mm,
which indicates a monofractal structural organization and smooth temporal
evolution. The magnitude of the filling factor is 0.04 from the Hinode SOT/SP
data and 0.07 from the MDI/HR data. The Hinode data show that at scales smaller
than 2 Mm, the filling factor decreases rapidly, which means a mutlifractal
structure and highly intermittent, burst-like energy release regime. The
absence of necessary complexity in CH magnetic fields at scales above 2 Mm
seems to be the most plausible reason why the net magnetic flux density does
not seem to be related to the solar wind speed: the energy release dynamics,
needed for solar wind acceleration, appears to occur at small scales below 1
Mm.Comment: 6 figures, approximately 23 pages. Accepted in Solar Physic
Irrigating with polyacrylamide (PAM) - Nine years and a million acres of experience
Polyacrylamide (PAM) has been available commercially since 1995 for reducing
irrigation-induced erosion and enhancing infiltration. The first series of practical field tests was
conducted in 1991. PAM used for erosion control is a large water soluble (non-crosslinked)
anionic molecule (12-15 megagrams per mole) containing < 0.05% acrylamide monomer. In
controlled field studies PAM eliminated, on average, 94% (80-99% range) of sediment loss in field
runoff from furrow irrigation, with a typical 15-50% relative infiltration increase on medium to fine
textured soils compared to untreated controls. Similar but less dramatic results have been seen with
sprinkler irrigation. Under some conditions infiltration is unchanged or can even be slightly
reduced, e.g. in sandy soils or where PAM application rates are very high. Results are achieved
with per irrigation field application rates of about 1 kg per hectare, for furrow irrigation, and 2 to 4
kg per hectare for sprinkler irrigation. Cost of PAM is 13 per kg. Seasonal application
totals vary from 3 to 7 kg per hectare. Farmer field sediment control has been around 80% of test
plot results. Substantial runoff reductions have been documented for nutrients, pesticides,
microorganisms, BOD, and weed seed. No adverse effects have been seen for soil microbial
populations. Crop yields have not been widely documented, though evidence exists for yield
increases related to infiltration improvement. High effectiveness, low cost, and ease of application,
compared to traditional conservation measures, has resulted in rapid technology acceptance in the
US and internationally. PAM-use for runoff water quality protection is one of the most potent
new irrigation environmental technologies in the market place. New uses in construction and
dryland erosion control are being developed rapidly. This paper discusses new insights and
understanding of PAM-use and potential for future development
On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
The sensitivity of a search for sources of TeV neutrinos can be improved by
grouping potential sources together into generic classes in a procedure that is
known as source stacking. In this paper, we define catalogs of Active Galactic
Nuclei (AGN) and use them to perform a source stacking analysis. The grouping
of AGN into classes is done in two steps: first, AGN classes are defined, then,
sources to be stacked are selected assuming that a potential neutrino flux is
linearly correlated with the photon luminosity in a certain energy band (radio,
IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino
production in AGN, this correlation is motivated by hadronic AGN models, as
briefly reviewed in this paper.
The source stacking search for neutrinos from generic AGN classes is
illustrated using the data collected by the AMANDA-II high energy neutrino
detector during the year 2000. No significant excess for any of the suggested
groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic
UrolitĂase: estudo comparativo em bovinos GuzerĂĄ oriundos de propriedades com e sem o problema
Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK
Background
A safe and efficacious vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), if deployed with high coverage, could contribute to the control of the COVID-19 pandemic. We evaluated the safety and efficacy of the ChAdOx1 nCoV-19 vaccine in a pooled interim analysis of four trials.
Methods
This analysis includes data from four ongoing blinded, randomised, controlled trials done across the UK, Brazil, and South Africa. Participants aged 18 years and older were randomly assigned (1:1) to ChAdOx1 nCoV-19 vaccine or control (meningococcal group A, C, W, and Y conjugate vaccine or saline). Participants in the ChAdOx1 nCoV-19 group received two doses containing 5âĂâ1010 viral particles (standard dose; SD/SD cohort); a subset in the UK trial received a half dose as their first dose (low dose) and a standard dose as their second dose (LD/SD cohort). The primary efficacy analysis included symptomatic COVID-19 in seronegative participants with a nucleic acid amplification test-positive swab more than 14 days after a second dose of vaccine. Participants were analysed according to treatment received, with data cutoff on Nov 4, 2020. Vaccine efficacy was calculated as 1â-ârelative risk derived from a robust Poisson regression model adjusted for age. Studies are registered at ISRCTN89951424 and ClinicalTrials.gov, NCT04324606, NCT04400838, and NCT04444674.
Findings
Between April 23 and Nov 4, 2020, 23â848 participants were enrolled and 11â636 participants (7548 in the UK, 4088 in Brazil) were included in the interim primary efficacy analysis. In participants who received two standard doses, vaccine efficacy was 62·1% (95% CI 41·0â75·7; 27 [0·6%] of 4440 in the ChAdOx1 nCoV-19 group vs71 [1·6%] of 4455 in the control group) and in participants who received a low dose followed by a standard dose, efficacy was 90·0% (67·4â97·0; three [0·2%] of 1367 vs 30 [2·2%] of 1374; pinteraction=0·010). Overall vaccine efficacy across both groups was 70·4% (95·8% CI 54·8â80·6; 30 [0·5%] of 5807 vs 101 [1·7%] of 5829). From 21 days after the first dose, there were ten cases hospitalised for COVID-19, all in the control arm; two were classified as severe COVID-19, including one death. There were 74â341 person-months of safety follow-up (median 3·4 months, IQR 1·3â4·8): 175 severe adverse events occurred in 168 participants, 84 events in the ChAdOx1 nCoV-19 group and 91 in the control group. Three events were classified as possibly related to a vaccine: one in the ChAdOx1 nCoV-19 group, one in the control group, and one in a participant who remains masked to group allocation.
Interpretation
ChAdOx1 nCoV-19 has an acceptable safety profile and has been found to be efficacious against symptomatic COVID-19 in this interim analysis of ongoing clinical trials
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