Serum Levels of 25‐Hydroxy‐Vitamin D3 Among Sun‐protected Outdoor Workers in Israel

The objective of this study was to evaluate the effect of reduced sun exposure of outdoor workers on vitamin D status using different modalities of sun protection, for primary prevention of skin cancer. 25‐OH‐D3 measurements were performed in two successive winters, 8 (interim) and 20 months after initiation of the study, in three groups of male outdoor workers, enrolled in either a complete, partial or minimal sun protection program. Ambient solar UVB radiation was monitored simultaneously. No intragroup or intergroup differences were observed between the interim‐ and postintervention measurements of mean 25‐OH‐D3, which were close to 30 ng mL^?1. Significant risk factors for postintervention 25‐OH‐D3 levels >33.8 ng mL^?1 (a surrogate for reduced sun protection) were: previous sunburn episodes (OR 2.5; 95% CI 1.01–6.3; P = 0.05) and younger age (OR 0.92; 95 CI 0.86–0.98; P = 0.009). Outdoor workers of Western, compared with those of Eastern paternal origin had a borderline significant risk (OR 2.4; 95% CI 0.9–6.3; P = 0.07). A borderline significant effect (OR 2.9; 95% CI 0.97–10.1; P = 0.085) was also noted for those in the minimal intervention group. In conclusion, sun protection among outdoor workers following a successful intervention did not suppress mean winter 25‐OH‐D3.     

Computable choice functions for computable linear orderings

A choice set for a computable linear ordering is a set which contains one element from each maximal block of the ordering. We obtain a partial characterization of the computable linear order‐types for which each computable model has a computable choice set, and a full characterization in the relativized case; Every model of the linear order‐type α of degree ≤ d has a choice set of degree ≤ d iff α can written as a finite sum of order‐types, each of which either has finitely many blocks, or has order‐type n · η for some integer n.     

Foundations of a Multi-way Spectral Clustering Framework for Hybrid Linear Modeling

The problem of Hybrid Linear Modeling (HLM) is to model and segment data using a mixture of affine subspaces. Different strategies have been proposed to solve this problem, however, rigorous analysis justifying their performance is missing. This paper suggests the Theoretical Spectral Curvature Clustering (TSCC) algorithm for solving the HLM problem and provides careful analysis to justify it. The TSCC algorithm is practically a combination of Govindu’s multi-way spectral clustering framework (CVPR 2005) and Ng et al.’s spectral clustering algorithm (NIPS 2001). The main result of this paper states that if the given data is sampled from a mixture of distributions concentrated around affine subspaces, then with high sampling probability the TSCC algorithm segments well the different underlying clusters. The goodness of clustering depends on the within-cluster errors, the between-clusters interaction, and a tuning parameter applied by TSCC. The proof also provides new insights for the analysis of Ng et al. (NIPS 2001). This work was supported by NSF grant #0612608.     

In vivo non-invasive studies on the human lens.

Progress in biophysical technology now permits us to monitor aging and precataractous changes in the human ocular lens in vivo as well as in vitro. We are employing two noninvasive techniques to measure changes in lens fluorescence and in one lens water compartment (T2) utilizing Scheimpflug lens fluorescence densitography and magnetic resonance imaging. These studies demonstrate age-related changes in the normal lens as reflected by enhanced fluorescence and longer T2 values. Precataractous changes can also be detected with this approach.     

Oscillation of flat layered shells with local elastic supports

The study of oscillation in thin-walled construction elements on elastic supports is of great practical interest. Various aspects of the problems of mechanics arising in this regard have been considered by many authors, especially in recent years. The authors of [4, 8, 13, 14, 17–19, 22] have presented voluminous graphical and tabular material for solid beams with elastic supports and for rectangular plates supported on rigid point supports along the edges and in the inner area; moreover, the authors of [22] present results relating to linear supports and circular plates, while in [5, 13, 18, and 22] the results reported have to do with the forms of the fundamental oscillation. In [5] the elastic bond is modelled by means of a Vinkperovskii foundation with a discontinuous bed coefficient. Cylindrical shells are examined in [1, 6], while in [21], for a spherical shell with elastic supports, an analytical solution is constructed. The authors of [23, 24] investigate the effect of an attached mass and a linear support for a circular and a rectangular plate, and a comparison with experimental data is made for a lower frequency. The close connection between the problems in question with those involving oscillation of shells with attached masses is reflected in [3, 7, 11, 16]. Analysis of the results obtained in the works mentioned above and in others shows that, unlike the case of beam systems, numerical results for plates and shells are significantly more difficult to obtain. Therefore, in the overwhelming majority of publications, thin plates and shells are examined, while to describe the process of their deformation classical models are used; here the supports, as a rule, are assumed to be absolutely rigid. The oscillation of anisotropic and, in particular, layered construction elements on elastic supports with further consideration of the bending rigidity of the latter clearly has not been studied sufficiently, which makes further research in this field timely. The present article examines layered, flat, orthotropic shells on a rectilinear layout, for which a solution of the static problem has been obtained previously [9, 10]. The basic assumptions of the computation method, developed for calculating the stress-deformed state (SDS) arising during driven oscillation of these objects far from the resonance points, as well as for determining the fundamental oscillation frequencies (FOF), are presented. Unlike traditional approaches, this method realizes the possibility of calculating, along with the normal reactions of elastic supports, reactive moments and tangential forces; in describing the movement of the system, the relations of the improved theory of shells are used [2].S. P. Timoshenko Institute of Mechanics of the Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 30, No. 2, pp. 55–60, February, 1994.     

Fronts,traveling fronts,and their stability in the generalized Swift-Hohenberg equation

The generalized Swift-Hohenberg equation with an additional quadratic term is studied. Time-stable localized stationary solutions of the pulse and front types are found. It is shown that stationary fronts give rise to traveling fronts, whose branches are also obtained. This study combines theoretical methods for dynamical systems (in particular, the theory of homo-and heteroclinic orbits) and numerical simulation.