Beneficiation of some Egyptian Glass Sands

The attrition-scrubbing of some Egyptian glass sands was necessary for the disintegration of the ferruginous clayey coating on quartz grains. The effects of time of attrition-ing, impeller speed and solid/liquid ration were investi-gated. Classification of the scrubbed sands resulted in the removal of a slimy fraction and yielded a product having 0.065% Fe. Acid attritioning of sand with commer-cial HCL at room temperature did not affect the iron, coat-ing quartz particles

The Coincidence Problem in Holographic f(R) Gravity

It is well-known that $f(R)$ gravity models formulated in Einstein conformal frame are equivalent to Einstein gravity together with a minimally coupled scalar field. In this case, the scalar field couples with the matter sector and the coupling term is given by the conformal factor. We apply the holographic principle to such interacting models. In a spatially flat universe, we show that the Einstein frame representation of $f(R)$ models leads to a constant ratio of energy densities of dark matter to dark energy.Comment: 10 pages, no figure

Reluctance of Students to Utilize Virtual Educational Environments in Public Schools: Real World Experiences

This study aimed to explore the perspectives of public-school students who were hesitant to use the Darsak Educational Platform (DEP) during the COVID-19 pandemic in order to understand their real-life experiences. To achieve the aim of the study, the researchers employed a qualitative approach in its phenomenological form. The study sample consisted of 12 male and female students from various public schools in Jordan. The participants were chosen using an intentional method. Semi-structured interviews were used to collect the data. The study’s findings revealed a variety of causes that contributed to students’ resistance to using DEP. These causes include the students’ lack of readiness to learn through DEP, the DEP’s failure to comply with international design standards, the inadequate physical and technical teaching environment, and the limited digital competencies of teachers needed in the virtual learning environment. Given the findings of this research, the researchers advise that additional consideration should be given to the design of DEP. They also advise providing students with appropriate guidance in the usage of educational platforms

Generation of Magnetic Field by Combined Action of Turbulence and Shear

The feasibility of a mean-field dynamo in nonhelical turbulence with superimposed linear shear is studied numerically in elongated shearing boxes. Exponential growth of magnetic field at scales much larger than the outer scale of the turbulence is found. The charateristic scale of the field is l_B ~ S^{-1/2} and growth rate is gamma ~ S, where S is the shearing rate. This newly discovered shear dynamo effect potentially represents a very generic mechanism for generating large-scale magnetic fields in a broad class of astrophysical systems with spatially coherent mean flows.Comment: 4 pages, 5 figures; replaced with revised version that matches the published PR

Mach's Principle and Model for a Broken Symmetric Theory of Gravity

We investigate spontaneous symmetry breaking in a conformally invariant gravitational model. In particular, we use a conformally invariant scalar tensor theory as the vacuum sector of a gravitational model to examine the idea that gravitational coupling may be the result of a spontaneous symmetry breaking. In this model matter is taken to be coupled with a metric which is different but conformally related to the metric appearing explicitly in the vacuum sector. We show that after the spontaneous symmetry breaking the resulting theory is consistent with Mach's principle in the sense that inertial masses of particles have variable configurations in a cosmological context. Moreover, our analysis allows to construct a mechanism in which the resulting large vacuum energy density relaxes during evolution of the universe.Comment: 9 pages, no figure

Expression of human Kallikrein 14 (KLK14) in breast cancer is associated with higher tumour grades and positive nodal status

Human kallikrein 14 (KLK14) is a steroid hormone-regulated member of the tissue kallikrein family of serine proteases, for which a prognostic and diagnostic value in breast cancer has been suggested. To further characterise the value of KLK14 as a breast tumour marker, we have carefully analysed KLK14 expression in normal breast tissue and breast cancer both on the RNA level by real-time RT-PCR (n=39), and on the protein level (n=127) using a KLK14-specific antibody for immunohistochemistry. We correlated KLK14 protein expression data with available clinico-pathological parameters (mean follow-up time was 55 months) including patient prognosis. KLK14 RNA expression as quantified by real-time RT-PCR was significantly more abundant in breast tumours compared to normal breast tissue (P=0.027), an issue that had not been clarified recently. Concordantly with the RNA data, cytoplasmic KLK14 protein expression was significantly higher in invasive breast carcinomas compared to normal breast tissues (P=0.003). Furthermore, KLK14 protein expression was associated with higher tumour grade (P=0.041) and positive nodal status (P=0.045) but was not significantly associated with shortened disease-free or overall patient survival time in univariate analyses. We conclude that KLK14 is clearly overexpressed in breast cancer in comparison to normal breast tissues and is positively associated with conventional parameters of tumour aggressiveness, but due to a missing association with survival times, the use of KLK14 immunohistochemistry as a prognostic marker in breast cancer is questionable

RELATIONSHIP OF GROWTH HORMONE RECEPTOR GENE WITH SOME OF PRODUCTIVE TRAITS OF COMMON CARP Cyprinus carpio

This study was aimed of determining the relationship of polymorphism of the growth hormone receptor gene with some of growth traits (daily growth rate, relative and specific growth, ratio and efficiency of feed conversion) in 45 samples of common carp (Cyprinus carpio). The following are the most important results obtained: The results of DNA sequencing and single nucleotide polymorphism (SNP) showed there are of three mutations in the following sites C24074T, A24375G and G24485A. No genetic makeup was significantly associated with the studied growth characteristics. It is concluded from this study that there is no significant effect of the difference in the genotypes of the growth hormone receptor gene on the growth characteristics of common carp fish

Multi-Service Group Key Establishment for Secure Wireless Mobile Multicast Networks

yesRecently there is high demand in distributing multimedia services over the internet to ubiquitous and computational intelligent mobile subscribers by the service providers (SPs). In this instance, provision of those services must be restricted to authorized subscribers via integration of authentication and group key management (GKM). GKM with diverse group services subscribed dynamically by moving subscribers in wireless networks has been omitted in conventional approaches. However it is expected that significant key management overhead will arise in them due to multi-services co-existing in the same network. In this paper, we propose a scalable decentralized multi-service GKM scheme considering host mobility in wireless environment. In the scheme, authentication of mobile subscribers and key management phases are delegated from the trusted domain key distributor (DKD) to the subgroup controllers known as area key distributors (AKD). The trusted intermediate AKDs can then establish and distribute the service group keys to valid subscribers in a distributed manner using identity-based encryption without involving the domain key distributor (DKD). This alleviates unnecessary delays and possible bottlenecks at the DKD. We show by simulation that the proposed scheme has some unique scalability properties over known schemes in terms of optimized rekeying communication and storage overheads. The security performance studies have shown resilience to various attacks