2,474 research outputs found
Point-source detection system rejects spatially extended radiation sources
System employing digital space correlation to suppress false target signals in a point-target tracking device is a reliable method for discriminating a distant target from false targets in the field of view of an infrared detection system or tracking device
Book Reviews
THE SILVERLAKE EXPERIMENT. By Lamar T. Empey and Steven G. Lubeck. Chicago: Aldine Publishing Company, 1971. Pp. x, 354. 10.00.
THE INTERNATIONAL LAW OF CIVIL WAR. Edited by Richard A. Falk. Baltimore: The Johns Hopkins Press, 1971. Pp. xix, 452. 6.95
Constraints from and the isotope effect for MgB
With the constraint that K, as observed for MgB, we use the
Eliashberg equations to compute possible allowed values of the isotope
coefficient, . We find that while the observed value can
be obtained in principle, it is difficult to reconcile a recently calculated
spectral function with such a low observed value
Irradiation-induced Ag nanocluster nucleation in silicate glasses: analogy with photography
The synthesis of Ag nanoclusters in sodalime silicate glasses and silica was
studied by optical absorption (OA) and electron spin resonance (ESR)
experiments under both low (gamma-ray) and high (MeV ion) deposited energy
density irradiation conditions. Both types of irradiation create electrons and
holes whose density and thermal evolution - notably via their interaction with
defects - are shown to determine the clustering and growth rates of Ag
nanocrystals. We thus establish the influence of redox interactions of defects
and silver (poly)ions. The mechanisms are similar to the latent image formation
in photography: irradiation-induced photoelectrons are trapped within the glass
matrix, notably on dissolved noble metal ions and defects, which are thus
neutralized (reverse oxidation reactions are also shown to exist). Annealing
promotes metal atom diffusion, which in turn leads to cluster nuclei formation.
The cluster density depends not only on the irradiation fluence, but also - and
primarily - on the density of deposited energy and the redox properties of the
glass. Ion irradiation (i.e., large deposited energy density) is far more
effective in cluster formation, despite its lower neutralization efficiency
(from Ag+ to Ag0) as compared to gamma photon irradiation.Comment: 48 pages, 18 figures, revised version publ. in Phys. Rev. B, pdf fil
Active Tension Network model suggests an exotic mechanical state realized in epithelial tissues.
Mechanical interactions play a crucial role in epithelial morphogenesis, yet understanding the complex mechanisms through which stress and deformation affect cell behavior remains an open problem. Here we formulate and analyze the Active Tension Network (ATN) model, which assumes that the mechanical balance of cells within a tissue is dominated by cortical tension and introduces tension-dependent active remodeling of the cortex. We find that ATNs exhibit unusual mechanical properties. Specifically, an ATN behaves as a fluid at short times, but at long times supports external tension like a solid. Furthermore, an ATN has an extensively degenerate equilibrium mechanical state associated with a discrete conformal - "isogonal" - deformation of cells. The ATN model predicts a constraint on equilibrium cell geometries, which we demonstrate to approximately hold in certain epithelial tissues. We further show that isogonal modes are observed in the fruit y embryo, accounting for the striking variability of apical areas of ventral cells and helping understand the early phase of gastrulation. Living matter realizes new and exotic mechanical states, the study of which helps to understand biological phenomena
Diagnostic and prognostic impact of serum HE4 detection in endometrial carcinoma patients
Background:To date, no good marker for screening or disease monitoring of endometrial cancer (EC) is available. The aims of this study were to investigate HE4 gene, protein expression and serum HE4 (sHE4) levels in a panel of ECs and normal endometria (NEs) and to correlate sHE4 with patient clinicopathological characteristics and prognosis.Methods:Using quantitative real-time PCR we tested 46 ECs and 20 NEs for HE4 gene expression. Protein expression was analysed by immunohistochemistry on tissue microarrays in 153 ECs and 33 NEs. Pre-operative serum samples from 138 EC and 76 NE patients were analysed with HE4-EIA assay. Association between sHE4 and patient clinicopathological characteristics or outcome was evaluated.Results:Protein and HE4 gene were significantly upregulated in EC tissues and sera, compared with controls. High sHE4 levels were significantly associated with worse EC clinical characteristics. By univariate survival analysis, high sHE4 levels significantly correlated with decreased overall survival, progression-free survival and disease-free survival, retaining their independent prognostic value on the poorly differentiated EC cohort.Conclusion:We demonstrate, for the first time, that high sHE4 levels correlates with an aggressive EC phenotype and may constitute an independent prognostic factor for poorly differentiated-ECs. Determination of sHE4 could be clinically useful in identifying high-risk EC patients for a more aggressive adjuvant therapy.British Journal of Cancer advance online publication, 5 April 2011; doi:10.1038/bjc.2011.109 www.bjcancer.com
The Qualitative Method of Impact Analysis
Consider the qualitative approach to evaluation design (as opposed to measurement) to be typified by a case study with a sample of just one. Although there have certainly been elaborate and emphatic defenses of the qualitative approach to program evaluation, such defenses rarely attempt to qualify the approach explicitly and rigorously as a method of impact analysis. The present paper makes that attempt. The problem with seeking to advance a qualitative method of impact analysis is that impact is a matter of causation and a non-quantitative approach to design is apparently not well suited to the task of establishing causal relations. The root of the difficulty is located in the counterfactual definition of causality, which is our only broadly accepted formal definition of causality for social science. It is not, however, the only definition we use informally. Another definition, labeled âphysical causality,â is widely used in practice and has recently been formalized. Physical causality can be applied to the present problem. For example, it explains the persuasiveness of Strivenâs âModus Operandiâ approach tailored case study design with a sample size of one in principle as strong a basis for making inferences program impact as a randomized experiment. Crucial program evaluation finding that peopleâs âoperative reasonsâ for doing what they do are the physical actions. it is shown that external validity using this qualitative approach would have exceptional strengths.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67113/2/10.1177_109821409902000106.pd
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