Yasser Ibrahim

Simple-Direct-Projective Modules

In this paper, we introduce and study the dual notion of simple-direct-injective modules. Namely, a right R-module M is called simple-direct-projective if, whenever A and B are submodules of M with B simple and M/A ≅ B ⊆⊕M, then A ⊆⊕M. Several characterizations of simple-direct-projective modules are provided and used to describe some well-known classes of rings. For example, it is shown that a ring R is artinian and serial with J2(R) = 0 if and only if every simple-direct-projective right R-module is quasi-projective if and only if every simple-direct-projective right R -module is a D3-module. It is also shown that a ring R is uniserial with J2(R) = 0 if and only if every simple-direct-projective right R-module is a C3-module if and only if every simple-direct-injective right R -module is a D3-module.

A review of impacts of temperature and relative humidity on various activities of honey bees

The importance of pollination services by honey bees (Apis mellifera L.) and their products is well-known. However, honey bee colonies currently face many challenges. These challenges include both biotic and abiotic factors. In this article, the impacts of abiotic factors (mainly temperature and relative humidity) on honey bee activities are reviewed. The suitable ranges of these two factors and the potential impacts of atypical minimal or maximal limits are presented. Social homeostasis of honey bees, and activities inside and outside the colony that are influenced by these two factors are included, followed by a suggestion of additional studies.

Simple-direct-modules

ABSTRACT A right R-module M is called simple-direct-injective if, whenever, A and B are simple submodules of M with A≅B, and B⊆⊕M, then A⊆⊕M. Dually, M is called simple-direct-projective if, whenever, A and B are submodules of M with M∕A≅B⊆⊕M and B simple, then A⊆⊕M. In this paper, we continue our investigation of these classes of modules strengthening many of the established results on the subject. For example, we show that a ring R is uniserial (artinian serial) with J2(R) = 0 iff every simple-direct-projective right R-module is an SSP-module (SIP-module) iff every simple-direct-injective right R-module is an SIP-module (SSP-module).

Rings whose cyclics are C3-modules

This is a study of rings whose cyclic modules are D3-modules with applications to rings whose cyclics are quasi-discrete and, respectively, discrete.

Rings all of whose right ideals are U-modules

ABSTRACT The notion of a U-module was introduced and thoroughly investigated in [11] as a strict and simultaneous generalization of quasi-continuous, square-free and automorphism-invariant modules. In this paper a right R-module M is called a U*-module if every submodule of M is a U-module, and a ring R is called a right U*-ring if RR is a U*-module. We show that M is a U*-module iff whenever A and B are submodules of M with A≅B and A∩B = 0, A⊕B is a semisimple summand of M; equivalently M = X⊕Y, where X is semisimple, Y is square-free, and X & Y are orthogonal. In particular, a ring R is a right U*-ring iff R is a direct product of a square-full semisimple artinian ring and a right square-free ring. Moreover, right U*-rings are shown to be directly-finite, and if the ring is also an exchange ring then it satisfies the substitution property, has stable-range 1, and hence is stably-finite. These results are non-trivial extensions of similar ones on rings all of whose right ideals are either quasi-continuous or auto-invariant.

C4- and D4-Modules via perspective direct summands

ABSTRACT In this article, we study the C4- and D4-modules in terms of perspective direct summands, providing new characterizations and results. Endomorphism rings of C4-modules and extensions of right C4-rings are also investigated. Decompositions of C4-modules with restricted ACC on direct summands and D4-modules with restricted DCC on direct summands are obtained.

Artinian serial rings R with J3(R) = 0

In this paper, we provide several new and interesting characterizations of artinian serial rings R with J3(R) = 0. Our results are nontrivial extensions of known results on the well-established cla...

Factors affecting the quality of mated honey bee queens stored for different periods in queen-right bank colonies. Effect of cage level and position on holding frame

The effect of storage cage level (upper or lower) and its position (peripheral or middle positions) on weight, survival rate and egg laying capacity of honey bee queens stored in queen-right colonies for various storage periods was studied. Storing mated queens in this way had a significant effect on their weight after 75 days of storage. The means of queen weight were 174.9 and 167.4 mg for the upper and lower strips, respectively showing the superiority of the upper one. A significant increase in the mean weight of queens stored in the middle position (172.5 mg) was noticed comparing to peripheral ones (169.8 mg). All the stored queens had significantly greater weight than their original weight before storage during the different periods of experiment. There were significant differences in the survival rate of mated queens stored in different levels, as the mean survival rate of queens stored in the upper strip (69.3%) was higher than the survival rate of mated queens stored in the lower one (60.1%). The queens stored in middle position attained a significantly higher survival rate (70.7%), than those stored in peripheral ones (58.7%).The overall survival rate was negatively influenced with the increase of storing period. In respect of egg laying capacity measured as sealed worker brood area, queens stored for 45 days produced a significantly larger sealed brood area (875.5 cm2) than that produced by queens stored for 75 days (843.2 cm2).

Effect of Queens Density, Cage Level and Position of Honeybee Mated Queens Stored for Different Periods in Queen-Right Bank Colonies on Their Supersedure Rate

Citation: Egypt. Acad. J. Biolog. Sci. (A. Entomology) Vol.9 (1)pp. 109-119(2016) Egyptian Academic Journal of Biological Sciences is the official English language journal of the Egyptian Society for Biological Sciences, Department of Entomology, Faculty of Sciences Ain Shams University. Entomology Journal publishes original research papers and reviews from any entomological discipline or from directly allied fields in ecology, behavioral biology, physiology, biochemistry, development, genetics, systematics, morphology, evolution, control of insects, arachnids, and general entomology. www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.

Rad-Projective and Strongly Rad-Projective Modules

We introduce the dual notion to soc-injectivity, namely rad-projective and strongly rad-projective modules. Several interesting results and applications on the new notion are obtained.