3,407 research outputs found
Metallurgical Applications of Polarized Light
Very little has been written concerning the theory of the metallurgical polarization microscope. Records of metallurgical studies utilizing this instrument are widely scattered among the literature, and are mostly material of an uncoordinated and irrelevant nature. It is the feeling of the author that a coordinated investigation of the metallurgical applications of polarized light will yield results providing the metallurgist with another means for the study of metals and their properties
The Age-Specific Force of Natural Selection and Walls of Death
W. D. Hamilton's celebrated formula for the age-specific force of natural
selection furnishes predictions for senescent mortality due to mutation
accumulation, at the price of reliance on a linear approximation. Applying to
Hamilton's setting the full non-linear demographic model for mutation
accumulation of Evans et al. (2007), we find surprising differences. Non-linear
interactions cause the collapse of Hamilton-style predictions in the most
commonly studied case, refine predictions in other cases, and allow Walls of
Death at ages before the end of reproduction. Haldane's Principle for genetic
load has an exact but unfamiliar generalization.Comment: 27 page
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Imaging Hepatocellular Carcinoma With 68Ga-Citrate PET: First Clinical Experience.
While cross-sectional imaging with computed tomography (CT) and magnetic resonance imaging is the primary method for diagnosing hepatocellular carcinoma (HCC), they provide little biological insight into this molecularly heterogeneous disease. Nuclear imaging tools that can detect molecular subsets of tumors could greatly improve diagnosis and management of HCC. To this end, we conducted a patient study to determine whether HCC can be resolved using 68Ga-citrate positron emission tomography (PET). One patient with recurrent HCC was injected with 300 MBq of 68Ga-citrate and imaged with PET/CT 249 minutes post injection. Four (28%) of 14 hepatic lesions were avid for 68Ga-citrate. One extrahepatic lesion was not PET avid. The average maximum standardized uptake value (SUVmax) for the lesions was 7.2 (range: 6.2-8.4), while the SUVmax of the normal liver parenchyma was 4.7 and blood pool was 5.7. The avid lesions were not significantly larger than the quiescent lesions, and a prior contrast CT showed uniform enhancement among the lesions, suggesting that tumor signals are due to specific binding of the radiotracer to the transferrin receptor, rather than enhanced vascularity in the tumor microenvironment. Further studies are required in a larger patient cohort to verify the molecular basis of radiotracer uptake and the clinical utility of this tool
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Prevalence of axial spondyloarthritis in patients with inflammatory bowel disease using cross-sectional imaging: a systematic literature review.
BACKGROUND: Patients with inflammatory bowel disease (IBD) have an excess burden of axial spondyloarthritis (axSpA), which, if left untreated, may significantly impact on clinical outcomes. We aimed to estimate the prevalence of axSpA, including previously undiagnosed cases, in IBD patients from studies involving cross-sectional imaging and identify the IBD features potentially associated with axSpA. METHODS: PubMed, Embase and Cochrane databases were searched systematically between 1990 and 2018. Article reference lists and key conference abstract lists from 2012 to 2018 were also reviewed. All abstracts were reviewed by two authors to determine eligibility for inclusion. The study inclusion criteria were (a) adults aged 18 years or above, (b) a clinical diagnosis of IBD and (c) reporting identification of sacroiliitis using cross-sectional imaging. RESULTS: A total of 20 observational studies were identified: 12 used CT, 6 used MR and 2 utilised both computed tomography (CT) and magnetic resonance (MR) imaging. Sample sizes ranged from 25 to 1247 (a total of 4096 patients); 31 studies were considered to have low selection bias, 13 included two or more radiology readers, and 3 included rheumatological assessments. The prevalence of sacroiliitis, the most commonly reported axSpA feature, ranged from 2.2% to 68.0% with a pooled prevalence of 21.0% [95% confidence interval (CI) 17-26%]. Associated IBD features include increasing IBD duration, increasing age, male sex, IBD location, inflammatory back pain and peripheral arthritis. No significant difference in the prevalence of sacroiliitis between Crohn's disease and ulcerative colitis was identified. Study limitations include variability in the individual study sample sizes and patient demographics. CONCLUSION: This review highlights the need for larger, well-designed studies using more sensitive imaging modalities and multivariable modelling to better estimate the prevalence of axSpA in IBD. An improved knowledge of the IBD phenotype(s) associated with axSpA and use of cross-sectional imaging intended for IBD assessment to screen for axSpA may help clinicians identify those patients most at risk
High Temperature Laser Sintering: An investigation into mechanical properties and shrinkage characteristics of Poly (Ether Ketone) structures
Copyright © 2014 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Materials and Design. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials and Design, Vol. 61 (2014). DOI: 10.1016/j.matdes.2014.04.035This paper presents an investigation into the properties of Poly Ether Ketone (PEK) components using the commercial high temperature laser sintering system, EOSINT P800. The shrinkage and the mechanical performance of components across the entire build chamber have been tested and a non-linear shrinkage profile has been obtained. The middle of the build chamber recorded the highest degree of shrinkage and the shrinkage in Z direction had the largest variation. The laser sintered components built in X and Y directions recorded a 10% lower tensile strength than the injection moulded samples of the same material where those built in the Z direction showed an approximately 50% decrease in strength in comparison with the injection moulded test specimens. The crystallinity between the skin and the core of the sintered samples was different; varied with the position within the build chamber and coincided with noticeable sample colour changes
Control Systems’ Effect on Attributional Processes and Sales Outcomes: A Cybernetic Information-Processing Perspective
Built upon a cybernetic information-processing framework, this article advances and empirically tests a conceptual model proposing the relationships between sales controls (outcome, activity, capability), salespeople’s attributional ascriptions (effort, strategy, ability), attributional dimensions (internal/external, stable/unstable), and psychological consequences (job satisfaction, performance expectation). The study challenges the assumption in the sales literature that attributional dimensions cleanly map onto attributional ascriptions. Findings support that sales control systems affect salespeople’s attribution processes in ways suggesting that the processes are more malleable than heretofore theorized in the marketing literature. Furthermore, the study demonstrates that control systems differentially affect attribution processes across two cultures: the United States and China. The article concludes with a discussion of research and managerial implications.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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An introduction to Trends in Extreme Weather and Climate Events: Observations, Socioeconomic Impacts, Terrestrial Ecological Impacts, and Model Projections
Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.Integrative Biolog
High Mass Triple Systems: The Classical Cepheid Y Car
We have obtained an HST STIS ultraviolet high dispersion Echelle mode
spectrum the binary companion of the double mode classical Cepheid Y Car. The
velocity measured for the hot companion from this spectrum is very different
from reasonable predictions for binary motion, implying that the companion is
itself a short period binary. The measured velocity changed by 7 km/ s during
the 4 days between two segments of the observation confirming this
interpretation. We summarize "binary" Cepheids which are in fact members of
triple system and find at least 44% are triples. The summary of information on
Cepheids with orbits makes it likely that the fraction is under-estimated.Comment: accepted by A
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