Background: Vitamin D (Vit D) deficiency is one of the major nutritional deficiencies in children. Obesity has inverse association with vitamin D levels. The aim of this study was to determine the differences in response to conventional treatment for Vit D deficiency and insufficiency in obese and normal weight children and adolescents.Methods: This nested case control study was conducted in 69...

In this paper, we present an open and safe nested transaction model. We discuss the concurrency control and recovery algorithms for our model. Our nested transaction model uses the notion of a recovery point subtransaction in the nested transaction tree. It incorporates a prewrite operation before each write operation to increase the potential concurrency. Our transaction model is termed ``open...

The quality of estimation of variance components depends on the design used as well as on the unknown values of the variance components. In this article, three designs are compared, namely, the balanced, staggered, and inverted nested designs for the three-fold nested random model. The comparison is based on the so-called quantile dispersion graphs, introduced in Khuri (1997), using analysis of...

In previous papers ([2], [3], [7]) feedback guided loop scheduling algorithms have been shown to be very effective for certain loop scheduling problems. In particular they perform well for problems that involve a sequential outer loop and a parallel inner loop, and timing information gathered during one execution of the parallel inner loop can be used to inform the scheduling of the subsequent ...

SQL-99 allows for nested subqueries at nearly all places within a query. From a user’s point of view, nested queries can greatly simplify the formulation of complex queries. However, nested queries that are correlated with the outer queries frequently lead to dependent joins with nested loops evaluations and thus poor performance. Existing systems therefore use a number of heuristics to unnest ...

In traditional relational databases, the data is stored in \ at" tables. Query processing performance is dominated by the cost of joining such tables. By contrast, nested relational structures can avoid joins. If, however, such structures are decomposed into nested normal form (NNF) then the number of normal scheme trees in the resulting nested scheme forest may dominate query processing perfor...

BACKGROUND Nested case-control studies become increasingly popular as they can be very efficient for quantifying the diagnostic accuracy of costly or invasive tests or (bio)markers. However, they do not allow for direct estimation of the test's predictive values or post-test probabilities, let alone for their confidence intervals (CIs). Correct estimates of the predictive values itself can easi...