5,444 research outputs found
Quantum-Classical Transition of the Escape Rate of a Uniaxial Spin System in an Arbitrarily Directed Field
The escape rate \Gamma of the large-spin model described by the Hamiltonian H
= -DS_z^2 - H_zS_z - H_xS_x is investigated with the help of the mapping onto a
particle moving in a double-well potential U(x). The transition-state method
yields in the moderate-damping case as a Boltzmann average of the
quantum transition probabilities. We have shown that the transition from the
classical to quantum regimes with lowering temperature is of the first order
(d\Gamma/dT discontinuous at the transition temperature T_0) for h_x below the
phase boundary line h_x=h_{xc}(h_z), where h_{x,z}\equiv H_{x,z}/(2SD), and of
the second order above this line. In the unbiased case (H_z=0) the result is
h_{xc}(0)=1/4, i.e., one fourth of the metastability boundary h_{xm}=1, at
which the barrier disappears. In the strongly biased limit \delta\equiv 1-h_z
<< 1, one has h_{xc} \cong (2/3)^{3/4}(\sqrt{3}-\sqrt{2})\delta^{3/2}\cong
0.2345 \delta^{3/2}, which is about one half of the boundary value h_{xm} \cong
(2\delta/3)^{3/2} \cong 0.5443 \delta^{3/2}.The latter case is relevant for
experiments on small magnetic particles, where the barrier should be lowered to
achieve measurable quantum escape rates.Comment: 17 PR pages, 16 figures; published versio
A Simplified Method to Distinguish Farmed (Salmo salar) from Wild Salmon: Fatty Acid Ratios Versus Astaxanthin Chiral Isomers
Mislabeling of farmed and wild salmon sold in markets has been reported. Since the fatty acid content of fish may influence human health and thus consumer behavior, a simplified method to identify wild and farmed salmon is necessary. Several studies have demonstrated differences in lipid profiles between farmed and wild salmon but no data exists validating these differences with government-approved methods to accurately identify the origin of these fish. Current methods are both expensive and complicated, using highly specialized equipment not commonly available. Therefore, we developed a testing protocol using gas chromatography (GC), to determine the origin of salmon using fatty acid profiles. We also compared the GC method with the currently approved FDA (United States Food and Drug Administration) technique that uses analysis of carotenoid optical isomers and found 100% agreement. Statistical validation (n = 30) was obtained showing elevated 18:2n-6 (z = 4.56; P = 0.0001) and decreased 20:1n-9 (z = 1.79; P = 0.07) in farmed samples. The method is suitable for wide adaptation because fatty acid methyl ester analysis is a well-established procedure in labs that conduct analysis of lipid composition and food constituents. GC analysis for determining the origin of North American salmon compared favorably with the astaxanthin isomer technique used by the FDA and showed that the fatty acid 18:2n-6 was the key indicator associated with the origin of these salmon
Cytogerontology since 1881: A reappraisal of August Weismann and a review of modern progress
Cytogerontology, the science of cellular ageing, originated in 1881 with the prediction by August Weismann that the somatic cells of higher animals have limited division potential. Weismann's prediction was derived by considering the role of natural selection in regulating the duration of an organism's life. For various reasons, Weismann's ideas on ageing fell into neglect following his death in 1914, and cytogerontology has only reappeared as a major research area following the demonstration by Hayflick and Moorhead in the early 1960s that diploid human fibroblasts are restricted to a finite number of divisions in vitro.
In this review we give a detailed account of Weismann's theory, and we reveal that his ideas were both more extensive in their scope and more pertinent to current research than is generally recognised. We also appraise the progress which has been made over the past hundred years in investigating the causes of ageing, with particular emphasis being given to (i) the evolution of ageing, and (ii) ageing at the cellular level. We critically assess the current state of knowledge in these areas and recommend a series of points as primary targets for future research
The Ciliate Paramecium Shows Higher Motility in Non-Uniform Chemical Landscapes
We study the motility behavior of the unicellular protozoan Paramecium tetraurelia in a microfluidic device that can be prepared with a landscape of attracting or repelling chemicals. We investigate the spatial distribution of the positions of the individuals at different time points with methods from spatial statistics and Poisson random point fields. This makes quantitative the informal notion of “uniform distribution” (or lack thereof). Our device is characterized by the absence of large systematic biases due to gravitation and fluid flow. It has the potential to be applied to the study of other aquatic chemosensitive organisms as well. This may result in better diagnostic devices for environmental pollutants.University of Wisconsin--Milwaukee (SURF (Salary for Undergraduate Research Fellows) Award)National Science Foundation (U.S.) (grant DMS-016214
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Measurement of triple gauge boson couplings from W⁺W⁻ production at LEP energies up to 189 GeV
A measurement of triple gauge boson couplings is presented, based on W-pair data recorded by the OPAL detector at LEP during 1998 at a centre-of-mass energy of 189 GeV with an integrated luminosity of 183 pb⁻¹. After combining with our previous measurements at centre-of-mass energies of 161–183 GeV we obtain κ = 0.97_{-0.16}^{+0.20}, g_{1}^{z} = 0.991_{-0.057}^{+0.060} and λ = -0.110_{-0.055}^{+0.058}, where the errors include both statistical and systematic uncertainties and each coupling is determined by setting the other two couplings to their Standard Model values. These results are consistent with the Standard Model expectations
Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis
Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size-fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size-fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change
1960: Abilene Christian College Lectures - Full Text
Table of Contents:
Theme Speeches: Christian Faith in the Modern World
Basis of Faith - Leonard Mullens - 9
Authority in Christianity - John T. Smithson, Jr. - 27
Origin and Preservation of the Bible - Neil R. Lightfoot - 44
Alleged Discrepancies of the Bible - David H. Bobo - 62
The Unity of the Bible - Jack Meyer - 91
Faith and Reason - Joe Sanders - 115
The Reasonableness of Supernaturalism - Virgil Trout - 126
The Present Statue of the Doctrine of Organic Evolution - J.D. Thomas - 146
The Nature of Man - Roy F. Osborne, Jr. - 181
Modern Challenges to Christian Morals - Carl Spain - 199
The Christ, Whose Son is He? - Gordon Teel - 232
Special Speeches
Teaching the Word of God in Korea - L. Haskell Chessfire - 255
The Influence of Christian Education - Judge Jack Pope - 276
Mission Opportunities in the Far East - Harry Robert Fox - 288
Mission Work in Austria - Robert Skelton - 303
Report from Switzerland - Heinrich Blum - 313
The Work in Nigeria - Rees Byrant - 320
The Training of Evangelists in Foreign Fields - Reiner Kallus - 331
Christian Scholarships - Everett Ferguson - 340
Evangelizing the World - A.R. Holton - 349
Panel Discussions
The Significance of the Dead Sea Scrolls
The Scrolls and the Text of the Bible - Paul Rotenberry - 357
The Relation between the Religion of the Essenes and that of Early Christians - Jay Smith - 366
Biblical Interpretation
Expediency and Pattern Authority - J.W. Roberts - 381
Examples in Pattern Authority - Thomas B. Warren - 392
Mental Health and Sin
The Present State of Mental Health Knowledge - Donald R. Sime - 409
The Relationship of Mental Health Problems to Sin - Paul Easley - 421
The Teenager
The Problems of Youth - Mack Wayne Craig - 432
Influences for Good - Wyatt Sawyer - 443
The Benefits of Abilene Christian College
To the Church - Hulen Jackson - 451
To The Home - Robert S. Bell - 459
\u27To the Community - Louie Welch - 465
Expenses At Abilene Christian College - James C. Kerr - 469
The Graduate School at Abilene Christian College
What I Am Getting Now in the ACC Graduate Program - Harold Vanderpool - 475
How the ACC Graduate Program Has Stood Up - Everett Ferguson - 481
What the ACC Graduate Program Ought To Be - Frank Pack - 486
The Importance to the Church of the ACC Graduate Program A.R. Holton - 490
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Acute kidney disease and renal recovery : consensus report of the Acute Disease Quality Initiative (ADQI) 16 Workgroup
Consensus definitions have been reached for both acute kidney injury (AKI) and chronic kidney disease (CKD) and these definitions are now routinely used in research and clinical practice. The KDIGO guideline defines AKI as an abrupt decrease in kidney function occurring over 7 days or less, whereas CKD is defined by the persistence of kidney disease for a period of > 90 days. AKI and CKD are increasingly recognized as related entities and in some instances probably represent a continuum of the disease process. For patients in whom pathophysiologic processes are ongoing, the term acute kidney disease (AKD) has been proposed to define the course of disease after AKI; however, definitions of AKD and strategies for the management of patients with AKD are not currently available. In this consensus statement, the Acute Disease Quality Initiative (ADQI) proposes definitions, staging criteria for AKD, and strategies for the management of affected patients. We also make recommendations for areas of future research, which aim to improve understanding of the underlying processes and improve outcomes for patients with AKD
Viral-mediated oncolysis is the most critical factor in the late-phase of the tumor regression process upon vaccinia virus infection
<p>Abstract</p> <p>Background</p> <p>In principle, the elimination of malignancies by oncolytic virotherapy could proceed by different mechanisms - e.g. tumor cell specific oncolysis, destruction of the tumor vasculature or an anti-tumoral immunological response. In this study, we analyzed the contribution of these factors to elucidate the responsible mechanism for regression of human breast tumor xenografts upon colonization with an attenuated vaccinia virus (VACV).</p> <p>Methods</p> <p>Breast tumor xenografts were analyzed 6 weeks post VACV infection (p.i.; regression phase) by immunohistochemistry and mouse-specific expression arrays. Viral-mediated oncolysis was determined by tumor growth analysis combined with microscopic studies of intratumoral virus distribution. The tumor vasculature was morphologically characterized by diameter and density measurements and vessel functionality was analyzed by lectin perfusion and extravasation studies. Immunological aspects of viral-mediated tumor regression were studied in either immune-deficient mouse strains (T-, B-, NK-cell-deficient) or upon cyclophosphamide-induced immunosuppression (MHCII<sup>+</sup>-cell depletion) in nude mice.</p> <p>Results</p> <p>Late stage VACV-infected breast tumors showed extensive necrosis, which was highly specific to cancer cells. The tumor vasculature in infected tumor areas remained functional and the endothelial cells were not infected. However, viral colonization triggers hyperpermeability and dilatation of the tumor vessels, which resembled the activated endothelium in wounded tissue. Moreover, we demonstrated an increased expression of genes involved in leukocyte-endothelial cell interaction in VACV-infected tumors, which orchestrate perivascular inflammatory cell infiltration. The immunohistochemical analysis of infected tumors displayed intense infiltration of MHCII-positive cells and colocalization of tumor vessels with MHCII<sup>+</sup>/CD31<sup>+ </sup>vascular leukocytes. However, GI-101A tumor growth analysis upon VACV-infection in either immunosuppressed nude mice (MHCII<sup>+</sup>-cell depleted) or in immune-deficient mouse strains (T-, B-, NK-cell-deficient) revealed that neither MHCII-positive immune cells nor T-, B-, or NK cells contributed significantly to VACV-mediated tumor regression. In contrast, tumors of immunosuppressed mice showed enhanced viral spreading and tumor necrosis.</p> <p>Conclusions</p> <p>Taken together, these results indicate that VACV-mediated oncolysis is the primary mechanism of tumor shrinkage in the late regression phase. Neither the destruction of the tumor vasculature nor the massive VACV-mediated intratumoral inflammation was a prerequisite for tumor regression. We propose that approaches to enhance viral replication and spread within the tumor microenvironment should improve therapeutical outcome.</p
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