520 research outputs found
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TECHNICAL JUSTIFICATION FOR CHOOSING PROPANE AS A CALIBRATION AGENT FOR TOTAL FLAMMABLE VOLATILE ORGANIC COMPOUND (VOC) DETERMINATIONS
This document presents the technical justification for choosing and using propane as a calibration standard for estimating total flammable volatile organic compounds (VOCs) in an air matrix. A propane-in-nitrogen standard was selected based on a number of criteria: (1) has an analytical response similar to the VOCs of interest, (2) can be made with known accuracy and traceability, (3) is available with good purity, (4) has a matrix similar to the sample matrix, (5) is stable during storage and use, (6) is relatively non-hazardous, and (7) is a recognized standard for similar analytical applications. The Waste Retrieval Project (WRP) desires a fast, reliable, and inexpensive method for screening the flammable VOC content in the vapor-phase headspace of waste containers. Table 1 lists the flammable VOCs of interest to the WRP. The current method used to determine the VOC content of a container is to sample the container's headspace and submit the sample for gas chromatography--mass spectrometry (GC-MS) analysis. The driver for the VOC measurement requirement is safety: potentially flammable atmospheres in the waste containers must be allowed to diffuse prior to processing the container. The proposed flammable VOC screening method is to inject an aliquot of the headspace sample into an argon-doped pulsed-discharge helium ionization detector (Ar-PDHID) contained within a gas chromatograph. No actual chromatography is performed; the sample is transferred directly from a sample loop to the detector through a short, inert transfer line. The peak area resulting from the injected sample is proportional to the flammable VOC content of the sample. However, because the Ar-PDHID has different response factors for different flammable VOCs, a fundamental assumption must be made that the agent used to calibrate the detector is representative of the flammable VOCs of interest that may be in the headspace samples. At worst, we desire that calibration with the selected calibrating agent overestimate the value of the VOCs in a sample. By overestimating the VOC content of a sample, we want to minimize false negatives. A false negative is defined as incorrectly estimating the VOC content of the sample to be below programmatic action limits when, in fact, the sample,exceeds the action limits. The disadvantage of overestimating the flammable VOC content of a sample is that additional cost may be incurred because additional sampling and GC-MS analysis may be required to confirm results over programmatic action limits. Therefore, choosing an appropriate calibration standard for the Ar-PDHID is critical to avoid false negatives and to minimize additional analytical costs
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Tank characterization report for double-shell tank 241-AN-106
This document summarizes the information on the historical uses, present status, and the sampling and analysis results of waste store in Tank 241-AN-106. This report supports the requirements of Tri- Party Agreement Milestone M-44-09
N=1* in 5 dimensions: Dijkgraaf-Vafa meets Polchinski-Strassler
One of the powerful techniques to analyze the 5 dimensional Super Yang Mills
theory with a massive hypermultiplet (N=1*) is provided by the AdS/CFT
correspondence. It predicts that, for certain special values of the
hypermultiplet mass, this theory develops nonperturbative branches of the
moduli space as well as new light degrees of freedom.
We use the higher dimensional generalization of the matrix model/gauge theory
correspondence and recover all the prediction of the supergravity analysis. We
construct the map between the four dimensional holomorphic superpotential and
the five dimensional action and explicitly show that the superpotential is flat
along the nonperturbative branches. This is the first instance in which the
Dijkgraaf-Vafa method is used to analyze intrinsically higher dimensional
phenomena.Comment: 28 pages, Late
Penrose Limits of Orbifolds and Orientifolds
We study the Penrose limit of various AdS_p X S^q orbifolds. The limiting
spaces are waves with parallel rays and singular wave fronts. In particular, we
consider the orbifolds AdS_3 X S^3/\Gamma, AdS_5 X S^5/\Gamma and AdS_{4,7} X
S^{7,4}/\Gamma where \Gamma acts on the sphere and/or the AdS factor. In the
pp-wave limit, the wave fronts are the orbifolds C^2/\Gamma, C^4/\Gamma and R
XC^4/\Gamma, respectively. When desingularization is possible, we get
asymptotically locally pp-wave backgrounds (ALpp). The Penrose limit of
orientifolds are also discussed. In the AdS_5 X RP^5 case, the limiting
singularity can be resolved by an Eguchi-Hanson gravitational instanton. The
pp-wave limit of D3-branes near singularities in F-theory is also presented.
Finally, we give the embedding of D-dimensional pp-waves in flat M^{2,D} space.Comment: 20 pages, references adde
Risk accuracy of type 2 diabetes in middle aged adults: Associations with sociodemographic, clinical, psychological and behavioural factors
Objective To identify the proportion of individuals with an accurate perception of their risk of type 2 diabetes (T2D) prior to, immediately after and eight weeks after receiving a personalised risk estimate. Additionally, we aimed to explore what factors are associated with underestimation and overestimation immediately post-intervention. Methods Cohort study based on the data collected in the Diabetes Risk Communication Trial. We included 379 participants (mean age 48.9 (SD 7.4) years; 55.1 women) who received a genotypic or phenotypic risk estimate for T2D. Results While only 1.3 of participants perceived their risk accurately at baseline, this increased to 24.7 immediately after receiving a risk estimate and then dropped to 7.3 at eight weeks. Those who overestimated their risk at baseline continued to overestimate it, whereas those who underestimated their risk at baseline improved their risk accuracy. We did not identify any other characteristics associated with underestimation or overestimation immediately after receiving a risk estimate. Conclusion Understanding a received risk estimate is challenging for most participants with many continuing to have inaccurate risk perception after receiving the estimate. Practice implications Individuals who overestimate or underestimate their T2D risk before receiving risk information might require different approaches for altering their risk perception. © 2017 The Author
Penrose Limits and Non-local theories
We investigate Penrose limits of two classes of non-local theories, little
string theories and non-commutative gauge theories. Penrose limits of the
near-horizon geometry of NS5-branes help to shed some light on the high energy
spectrum of little string theories. We attempt to understand renormalization
group flow in these theories by considering Penrose limits wherein the null
geodesic also has a radial component. In particular, we demonstrate that it is
possible to construct a pp-wave spacetime which interpolates between the linear
dilaton and the AdS regions for the Type IIA NS5-brane. Similar analysis is
considered for the holographic dual geometry to non-commutative field theories.Comment: 27 pages, LaTeX; v2: added reference
Algebraic approach to quantum field theory on a class of noncommutative curved spacetimes
In this article we study the quantization of a free real scalar field on a
class of noncommutative manifolds, obtained via formal deformation quantization
using triangular Drinfel'd twists. We construct deformed quadratic action
functionals and compute the corresponding equation of motion operators. The
Green's operators and the fundamental solution of the deformed equation of
motion are obtained in terms of formal power series. It is shown that, using
the deformed fundamental solution, we can define deformed *-algebras of field
observables, which in general depend on the spacetime deformation parameter.
This dependence is absent in the special case of Killing deformations, which
include in particular the Moyal-Weyl deformation of the Minkowski spacetime.Comment: LaTeX 14 pages, no figures, svjour3.cls style; v2: clarifications and
references added, compatible with published versio
Adding flavor to the gravity dual of non-commutative gauge theories
We study the addition of flavor degrees of freedom to the supergravity dual
of the non-commutative deformation of the maximally supersymmetric gauge
theories. By considering D7 flavor branes in the probe approximation and
studying their fluctuations we extract the spectrum of scalar and vector mesons
as a function of the non-commutativity. We find that the spectrum for very
large non-commutative parameter is equal to the one in the commutative theory,
while for some intermediate values of the non-commutativity some of the modes
disappear from the discrete spectrum. We also study the semiclassical dynamics
of rotating open strings attached to the D7-brane, which correspond to mesons
with large spin. Under the effect of the non-commutativity the open strings get
tilted. However, at small(large) distances they display the same Regge-like
(Coulombic) behaviour as in the commutative theory. We also consider the
addition of D5-flavor branes to the non-commutative deformation of the N=1
supersymmetric Maldacena-Nunez background.Comment: 50 pages, 9 figures, LaTeX; v2: minor improvements, references added;
v3: typos correcte
On Supergravity Solutions of Branes in Melvin Universes
We study supergravity solutions of type II branes wrapping a Melvin universe.
These solutions provide the gravity description of non-commutative field
theories with non-constant non-commutative parameter. Typically these theories
are non-supersymmetric, though they exhibit some feature of their corresponding
supersymmetric theories. An interesting feature of these non-commutative
theories is that there is a critical length in the theory in which for
distances larger than this length the effects of non-commutativity become
important and for smaller distances these effects are negligible. Therefore we
would expect to see this kind of non-commutativity in large distances which
might be relevant in cosmology. We also study M5-brane wrapping on
11-dimensional Melvin universe and its descendant theories upon compactifying
on a circle.Comment: 25 pages, latex file; v2: typos corrected, Refs. adde
Mobilisation of arsenic from bauxite residue (red mud) affected soils: effect of pH and redox conditions
The tailings dam breach at the Ajka alumina plant, western Hungary in 2010 introduced ~1 million m3 of red mud suspension into the surrounding area. Red mud (fine fraction bauxite residue) has a characteristically alkaline pH and contains several potentially toxic elements, including arsenic. Aerobic and anaerobic batch experiments were prepared using soils from near Ajka in order to investigate the effects of red mud addition on soil biogeochemistry and arsenic mobility in soil–water experiments representative of land affected by the red mud spill. XAS analysis showed that As was present in the red mud as As(V) in the form of arsenate. The remobilisation of red mud associated arsenate was highly pH dependent and the addition of phosphate to red mud suspensions greatly enhanced As release to solution. In aerobic batch experiments, where red mud was mixed with soils, As release to solution was highly dependent on pH. Carbonation of these alkaline solutions by dissolution of atmospheric CO2 reduced pH, which resulted in a decrease of aqueous As concentrations over time. However, this did not result in complete removal of aqueous As in any of the experiments. Carbonation did not occur in anaerobic experiments and pH remained high. Aqueous As concentrations initially increased in all the anaerobic red mud amended experiments, and then remained relatively constant as the systems became more reducing, both XANES and HPLC–ICP-MS showed that no As reduction processes occurred and that only As(V) species were present. These experiments show that there is the potential for increased As mobility in soil–water systems affected by red mud addition under both aerobic and anaerobic conditions
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