415 research outputs found
Moving Mirror Model of Hawking Evaporation
The moving mirror model is designed to extract essential features of the
black hole formation and the subsequent Hawking radiation by neglecting
complication due to a finite curvature. We extend this approach to dynamically
treat back reaction against the mirror motion due to Hawking radiation. It is
found that a unique model in two spacetime dimensions exists in which Hawking
radiation completely stops and the end point of evaporation contains a
disconnected remnant. When viewed from asymptotic observers at one side of the
spacetime, quantum mechanical correlation is recovered in the end. Although the
thermal stage accompanying short range correlation may last for an arbitrarily
long period, at a much longer time scale a long tail of non-thermal correlation
is clearly detected.Comment: 39 pages, TU-94-452 (Corrupted figure file has been replaced. No
change of the text.
REMOVING THE CADMIUM, ARSENIC AND SULFATE IONS FROM WET PROCESS PHOSPHORIC ACID
Commercially, phosphoric acid is manufactured using different
processes. The
wet-process is the process applied in Syria using phosphate mineral, and
phosphoric acid produced by this process contains a variety of impurities.
This paper studies the precipitation of Cd, As and sulfate ions. The results
show that the yield of precipitation of sulfate ion increases by increasing the
concentration of barium carbonate and temperature. The precipitation of
arsenic increases by increasing the concentration of sodium sulfide and
temperature. The precipitation of cadmium was better under ambient
temperature by sodium sulfide
Gene Expression Profiling of Bronchoalveolar Lavage Cells Preceding a Clinical Diagnosis of Chronic Lung Allograft Dysfunction.
BackgroundChronic Lung Allograft Dysfunction (CLAD) is the main limitation to long-term survival after lung transplantation. Although CLAD is usually not responsive to treatment, earlier identification may improve treatment prospects.MethodsIn a nested case control study, 1-year post transplant surveillance bronchoalveolar lavage (BAL) fluid samples were obtained from incipient CLAD (n = 9) and CLAD free (n = 8) lung transplant recipients. Incipient CLAD cases were diagnosed with CLAD within 2 years, while controls were free from CLAD for at least 4 years following bronchoscopy. Transcription profiles in the BAL cell pellets were assayed with the HG-U133 Plus 2.0 microarray (Affymetrix). Differential gene expression analysis, based on an absolute fold change (incipient CLAD vs no CLAD) >2.0 and an unadjusted p-value â€0.05, generated a candidate list containing 55 differentially expressed probe sets (51 up-regulated, 4 down-regulated).ResultsThe cell pellets in incipient CLAD cases were skewed toward immune response pathways, dominated by genes related to recruitment, retention, activation and proliferation of cytotoxic lymphocytes (CD8+ T-cells and natural killer cells). Both hierarchical clustering and a supervised machine learning tool were able to correctly categorize most samples (82.3% and 94.1% respectively) into incipient CLAD and CLAD-free categories.ConclusionsThese findings suggest that a pathobiology, similar to AR, precedes a clinical diagnosis of CLAD. A larger prospective investigation of the BAL cell pellet transcriptome as a biomarker for CLAD risk stratification is warranted
An Unorthodox Introduction to QCD
These are lecture notes presented at the 2017 CTEQ Summer School at the
University of Pittsburgh and the 2018 CTEQ Summer School at the University of
Puerto Rico, Mayaguez. The title is a reference to hep-th/0309149 and
introduces perturbative QCD and its application to jet substructure from a
bottom-up perspective based on the approximation of QCD as a weakly-coupled,
conformal field theory. Using this approach, a simple derivation of the Sudakov
form factor with soft gluon emission modeled as a Poisson process is presented.
Topics of the identification and discrimination of quark- versus
gluon-initiated jets and jet grooming are also discussed.Comment: 16 pages, 18 figures. Comments welcome!, v2: updated to include both
lectures from the 2018 CTEQ schoo
Bern-Kosower Rule for Scalar QED
We derive a full Bern-Kosower-type rule for scalar QED starting from quantum
field theory: we derive a set of rules for calculating -matrix elements for
any processes at any order of the coupling constant. Gauge-invariant set of
diagrams in general is first written in the worldline path-integral expression.
Then we integrate over , and the resulting expression is given in
terms of correlation function on the worldline . Simple rules to decompose the correlation function into basic
elements are obtained. Gauge transformation known as integration by parts
technique can be used to reduce the number of independent terms before
integration over proper-time variables. The surface terms can be omitted
provided the external scalars are on-shell. Also, we clarify correspondence to
the conventional Feynman rule, which enabled us to avoid any ambiguity coming
from the infinite dimensionality of the path-integral approach.Comment: 38pages, 18 Postscript figures, uses epsf.st
Electronic structure investigation of CeB6 by means of soft X-ray scattering
The electronic structure of the heavy fermion compound CeB6 is probed by
resonant inelastic soft X-ray scattering using photon energies across the Ce 3d
and 4d absorption edges. The hybridization between the localized 4f orbitals
and the delocalized valence-band states is studied by identifying the different
spectral contributions from inelastic Raman scattering and normal fluorescence.
Pronounced energy-loss structures are observed below the elastic peak at both
the 3d and 4d thresholds. The origin and character of the inelastic scattering
structures are discussed in terms of charge-transfer excitations in connection
to the dipole allowed transitions with 4f character. Calculations within the
single impurity Anderson model with full multiplet effects are found to yield
consistent spectral functions to the experimental data.Comment: 9 pages, 4 figures, 1 table,
http://link.aps.org/doi/10.1103/PhysRevB.63.07510
BMC Public Health
Background Failure to retain HIV-positive pregnant women on antiretroviral therapy (ART) leads to increased mortality for the mother and her child. This study evaluated different retention measures for womenâs engagement along the continuum of care for prevention of mother-to-child transmission (PMTCT) option B+ services in Mozambique. Methods We compared âpointâ retention (patientâs presence in care 12-month post-ART initiation or any time thereafter) with the following definitions: alive and in care 12âmonth post-ART initiation (Ministry of Health; MOH); attendance at a health facility up to 15-month post-ART initiation (World Health Organization; WHO); alive and in treatment at 1-, 2-, 3-, 6-, 9-, and 12-month post-ART initiation (Inter-Agency Task Team; IATT); and alive and in care 12-month post-ART initiation with â„75% appointment adherence during follow-up (i.e. âappointment adherenceâ retention) or with â„75% of appointments met on time during follow-up (i.e. âon-time adherenceâ retention). Kaplan-Meier survival curves were produced to assess variability in retention rates. We used âon-time adherenceâ retention as our reference to estimate sensitivity, specificity, and proportion of misclassified patients. Results Considering the âpointâ retention definition, 16,840 HIV-positive pregnant women enrolled in option B+ PMTCT services were identified as âretained in careâ 12-month post-ART initiation. Of these, 60.3% (95% CI 59.6â61.1), 84.8% (95% CI 84.2â85.3), and 16.4% (95% CI 15.8â17.0) were classified as âretained in careâ using MOH, WHO, and IATT definitions, respectively, and 1.2% (95% CI 1.0â1.4) were classified as âretained in careâ using the ââ„75% on-time adherenceâ definition. All definitions provided specificity rates of â„98%. The sensitivity rates were 3.0% with 78% of patients misclassified according to the WHO definition and 4.3% with 54% of patients misclassified according to the MOH definition. The âpointâ retention definition misclassified 97.6% of patients. Using IATT and âappointment adherenceâ retention definitions, sensitivity rates (9.0 and 11.7%, respectively) were also low; however, the proportion of misclassified patients was smaller (15.9 and 18.3%, respectively). Conclusion More stringent definitions indicated lower retention rates for PMTCT programs. Policy makers and program managers should include attendance at follow-up visits when measuring retention in care to better guide planning, scale-up, and monitoring of interventions
Sedimentary context and palaeoecology of Gigantoproductus shell beds in the Mississippian Eyam Limestone Formation, Derbyshire carbonate platform, central England
A sedimentological study was conducted at two localities exposing the Mississippian Eyam Limestone Formation of the Derbyshire carbonate platform, UK. Ricklow Quarry comprises seven facies with diverse skeletal assemblages, representing deposition on the inner to middle ramp within open marine waters. Once-a-Week Quarry comprises four facies, dominated by crinoidal debris representing deposition on the inner ramp. Both localities expose Gigantoproductus shell beds. Palaeoecological analysis of a single shell bed from each locality enabled investigation of the rapid colonization and success of this taxon on the platform. At Ricklow Quarry, on the eastern side of a localized mud mound, both life (>72% of thin and thick-shelled brachiopods in life position) and neighbourhood assemblages are present. A low-moderate diversity community (<1.37 and <0.8 Shannon diversity index) rapidly established over relict Brigantian mud mounds. Shell beds are preluded by intervals of decreased energy that allowed larvae to settle. Once established, the dominance of thick-shelled individuals enabled baffling, potentially providing localized shelter for larvae and nearby individuals. At Once-a-Week Quarry, where no mud mound is present, only thick-shelled Gigantoproductus species and a low diversity community (<1.07 Shannon diversity index) exclusively comprising neighbourhood assemblages (37% in life position) is present. The presence of inactive mud mounds at Ricklow Quarry appears to have been the key to the success of Gigantoproductus species enabling the onset of stable communities in the shelter provided by the relict mound. Once the first palaeocommunities were established, larvae dispersed and colonized higher energy settings, such as at Once-a-Week Quarry
The mortality rates and the space-time patterns of John Snowâs cholera epidemic map
Background Snowâs work on the Broad Street map is widely known as a pioneering example of spatial epidemiology. It lacks, however, two significant attributes required in contemporary analyses of disease incidence: population at risk and the progression of the epidemic over time. Despite this has been repeatedly suggested in the literature, no systematic investigation of these two aspects was previously carried out. Using a series of historical documents, this study constructs own data to revisit Snowâs study to examine the mortality rate at each street location and the space-time pattern of the cholera outbreak. Methods This study brings together records from a series of historical documents, and prepares own data on the estimated number of residents at each house location as well as the space-time data of the victims, and these are processed in GIS to facilitate the spatial-temporal analysis. Mortality rates and the space-time pattern in the victimsâ records are explored using Kernel Density Estimation and network-based Scan Statistic, a recently developed method that detects significant concentrations of records such as the date and place of victims with respect to their distance from others along the street network. The results are visualised in a map form using a GIS platform. Results Data on mortality rates and space-time distribution of the victims were collected from various sources and were successfully merged and digitised, thus allowing the production of new map outputs and new interpretation of the 1854 cholera outbreak in London, covering more cases than Snowâs original report and also adding new insights into their space-time distribution. They confirmed that areas in the immediate vicinity of the Broad Street pump indeed suffered from excessively high mortality rates, which has been suspected for the past 160 years but remained unconfirmed. No distinctive pattern was found in the space-time distribution of victimsâ locations. Conclusions The high mortality rates identified around the Broad Street pump are consistent with Snowâs theory about cholera being transmitted through contaminated water. The absence of a clear space-time pattern also indicates the water-bourne, rather than the then popular belief of air bourne, nature of cholera. The GIS data constructed in this study has an academic value and would cater for further research on Snowâs map
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