A discontinuous Galerkin method for nonlinear shear-flexible shells

In this paper, a discontinuous Galerkin method for a nonlinear shear-flexible shell theory is proposed that is suitable for both thick and thin shell analysis. The proposed method extends recent work on Reissner–Mindlin plates to avoid locking without the use of projection operators, such as mixed methods or reduced integration techniques. Instead, the flexibility inherent to discontinuous Galerkin methods in the choice of approximation spaces is exploited to satisfy the thin plate compatibility conditions a priori. A benefit of this approach is that only generalized displacements appear as unknowns. We take advantage of this to craft the method in terms of a discrete energy minimization principle, thereby restoring the Rayleigh–Ritz approach. In addition to providing a straightforward and elegant derivation of the discrete equilibrium equations, the variational character of the method could afford numerous advantages in terms of mesh adaptation and available solution techniques. The proposed method is exercised on a set of benchmarks and example problems to assess its performance numerically, and to test for shear and membrane locking. Keywords: Shells; Discontinuous Galerkin; Locking; VariationalUnited States. Army Research Office (Contract DAAD-19-02-D-0002)United States. Office of Naval Research (Grant N00014-07-1-0764

Sleep directly following learning benefits consolidation of spatial associative memory

Contains fulltext : 128176.pdf (publisher's version ) (Open Access)The last decade has brought forth convincing evidence for a role of sleep in non-declarative memory. A similar function of sleep in episodic memory is supported by various correlational studies, but direct evidence is limited. Here we show that cued recall of face–location associations is significantly higher following a 12-h retention interval containing sleep than following an equally long period of waking. Furthermore, retention is significantly higher over a 24-h sleep–wake interval than over an equally long wake–sleep interval. This difference occurs because retention during sleep was significantly better when sleep followed learning directly, rather than after a day of waking. These data demonstrate a beneficial effect of sleep on memory that cannot be explained solely as a consequence of reduced interference. Rather, our findings suggest a competitive consolidation process, in which the fate of a memory depends, at least in part, on its relative stability at sleep onset: Strong memories tend to be preserved, while weaker memories erode still further. An important aspect of memory consolidation may thus result from the removal of irrelevant memory “debris.

Nutrition, social factors and prostatic cancer in a Northern Italian population.

The relationship between prostate cancer and indicators of nutrition, diet and social factors was evaluated in a case-control study of 166 patients with histologically confirmed prostatic carcinoma and 202 control subjects hospitalized for acute diseases other than malignant, hormonal or urogenital. The relative risk increased with increasing body mass index, men being moderately overweight showing a 2.3 elevated risk, and those grossly overweight an over four-fold higher risk of prostate cancer, when allowance was made for several identified potential confounding factors. Cases also reported more frequent consumption of milk and other dairy products and meat, but no significant difference was noted for vegetable intake. The risk of prostate cancer was unrelated to marital status or indicators of social class based on occupation

Selected medical conditions and risk of breast cancer.

Several diseases are known or suspected to be associated with altered levels of hormones and growth factors that may influence breast cancer risk. To elucidate this possibility, we studied the relationship between 23 medical conditions or procedures and breast cancer risk by means of data from a multicentric case-control study conducted between 1991 and 1994 in six Italian areas. The study included 2569 histologically confirmed incident cases of breast cancer (median age 55 years, range 23-74 years) and 2588 control women (median age 56 years, range 20-74 years) admitted to the same hospitals as cases for a variety of acute conditions unrelated to known or suspected risk factors for breast cancer. After allowance for education, parity and body mass index, elevated odds ratios (ORs) emerged for history of diabetes mellitus in post-menopausal women (OR = 1.5, 95% CI 1.1-2.0), hypertension in pregnancy (OR = 1.8, 95% CI 1.0-3.4) and breast nodules (OR = 1.3, 95% CI 1.0-1.7). Risk decreases were associated with ovarian ablation for ovarian cysts (OR = 0.5, 95% CI 0.3-0.7) and with thyroid nodules (OR = 0.7, 95% CI 0.5-0.9) but not with the combination of any type of benign thyroid disease. While most examined conditions seemed unrelated to breast cancer risk, the association with late-onset diabetes is of special interest as it suggests a role of hyperinsulinaemia and insulin resistance in breast cancer promotion. It also points to preventive lifestyle modifications