Mountain winds (revisited)

The prediction of extremely high wind speeds, at ground level on the downstream side of a mountain range, is possible by solving the initial value problem for a two-layered nonlinear shallow water model of the atmosphere. Three different numerical methods are described to find the solutions which may involve shocks: (1) the vonNeumann-Richtmyer artificial viscosity method, (2) a filtering scheme, and (3) a hybrid method

Numerical methods for meteorology and climatology

Efficient numerical methods for long term weather forecasting are developed. One implicit and one explicit scheme are compared as to accuracy

Microcomputer laboratories in mathematics education

AbstractThis article discusses the mathematical-educational potential of a computational laboratory at the pre-calculus and co-calculus levels. The laboratory envisaged is based on a set of microcomputers, whose use plays a central role in the teaching process, with particular emphasis on algorithmization. A new role for the mathematics teacher and professor is layed out, augmenting the “chalk and talk” methods by active participation as a laboratory instructor. Following a brief description of the integration of such a laboratory into the mathematical education, seven appropriate subjects are discussed, including some new relevant elementary proofs and worked out examples. Emphasis is placed upon the mathematical-educational byproducts (such as error bounds, ill-conditioning, complexity, rate of convergence, etc.) accompanying the implementation of these seven modules. Special attention is given to the removal of “black box” procedures and to the construction of “numerical methods that work”. Extensions and generalizations to more advanced topics are indicated, especially where the results in our modules may serve as points of departure in that direction

Functional polymorphisms in the P2X7 receptor gene are associated with stress fracture injury

Context: Military recruits and elite athletes are susceptible to stress fracture injuries. Genetic predisposition has been postulated to have a role in their development. The P2X7 receptor (P2X7R) gene, a key regulator of bone remodelling, is a genetic candidate that may contribute to stress fracture predisposition. Objective: To evaluate the putative contribution of P2X7R to stress fracture injury in two separate cohorts, military personnel and elite athletes. Methods: In 210 Israeli Defence Forces (IDF) military conscripts, stress fracture injury was diagnosed (n=43) based on symptoms and a positive bone scan. In a separate cohort of 518 elite athletes, self-reported medical imaging scan-certified stress fracture injuries were recorded (n=125). Non-stress fracture controls were identified from these cohorts who had a normal bone scan or no history or symptoms of stress fracture injury. Study participants were genotyped for functional SNPs within the P2X7R gene using proprietary fluorescence-based competitive allele-specific PCR assay. Pearson Chi-square (χ2) tests, corrected for multiple comparisons, were used to assess associations in genotype frequencies. Results: The variant allele of P2X7R SNP rs3751143 (Glu496Ala- loss of function) was associated with stress fracture injury, while the variant allele of rs1718119 (Ala348Thr- gain of function) was associated with a reduced occurrence of stress fracture injury in military conscripts (P<0.05). The association of the variant allele of rs3751143 with stress fractures was replicated in elite athletes (P<0.05), whereas the variant allele of rs1718119 was also associated with reduced multiple stress fracture cases in elite athletes (P<0.05). Conclusions: The association between independent P2X7R polymorphisms with stress fracture prevalence supports the role of a genetic predisposition in the development of stress fracture injury

CD1a expression by Barrett's metaplasia of gastric type may help to predict its evolution towards cancer

As emerging in the recent literature, CD1a has been regarded as a molecule whose expression may reflect tumour evolution. The aim of the present work was to investigate the expression of CD1a in a series of Barrett's metaplasia (BM), gastric type (GTBM), with and without follow-up, in order to analyse whether its expression may help to diagnose this disease and to address the outcome. Indeed, GTBM may be confused sometimes with islets of ectopic gastric mucosa and its evolution towards dysplasia (Dy) or carcinoma (Ca) could not be foreseen. We showed a significant higher expression of CD1a in GTBM than in both Dy and Ca; nevertheless, the number of positive GTBM was significantly lower in the group of cases that at follow-up underwent Dy or Ca. Our data address that CD1a may be a novel biomarker for BM and that its expression may help to predict the prognosis of this pathology