Let R be a ring, M a right R-module, and n a fixed non-negative integer. M is called n-cotorsion if Extn+1 R N M = 0 for any flat right R-module N . M is said to be n-flat if ExtR M N = 0 for any n-cotorsion right R-module N . We prove that ( n n is a complete hereditary cotorsion theory, where n (resp. n) denotes the class of all n-flat (resp. n-cotorsion) right R-modules. Several applications...

BACKGROUND Many studies have investigated the impact of a wide range of social events on suicide-related behaviour. However, these studies have predominantly examined national events. The aim of this study is to provide a statistical evaluation of the relationship between mass gatherings in some relatively small urban sub-populations and the general suicide rates of a major city. METHODS The ...

A retrospective study of 34,236 consecutive static line parachute descents by trained parachutists, in which 379 were injured, is described. Injury rates associated with extrinsic factors were compared and then analyzed using logistic regression. A table describing the association with extrinsic factors, with relative risks, is at Annex A. The overall injury rate was 1.11% (1.11 injured per 100...

objective: for investigation of intercropping of maize and faba bean, an experiment was conducted in research station of agriculture faculty of tabriz university during growing season of 2013. methods: experimental design was randomized complete block design with three replications and seven treatment. treatments included one row intercropping (1:1), 4 strip intercropping pattern with ratios of...

for entire functions, the notions of their growth indicators such as ritt order are classical in complex analysis. but the concepts of relative ritt order of entire functions and as well as their technical advantages of not comparing with the growths of $exp exp z$ are not at all known to the researchers of this area. therefore the studies of the growths of entire functions in the light of thei...