Skills as a factor in livestock production in Egypt

In the agricultural economy of Egypt the livestock industry has not developed as rapidly as the production of crops. The production of livestock, however, is becoming more important and the Egyptians are rapidly recognising the value livestock contributes to their livelihood. Its importance is keenly felt when the landlord and peasant experience low prices for their crops, principally cotton, and thus are without an adequate source of income to help offset the instability of their income. Also, the pressing need for organic manures to overcome part of the fertility problem of the land Is of great importance to Egyptian agriculture. Soil depletion is of particular significance since crop yields have not improved as they should have in recent years. This has been due partly to the scarcity of available chemical fertilizers during the World War II period when production had to be concentrated on grains to feed the Allied troops, and because the same practices for planting and tilling the soil as were used 5,000 years ago are still predominant. In order to better understand the role livestock might have in the future development of Egyptian agriculture, it will be helpful if one understands some of the different characteristics and the setting in which the livestock enterprise prevails

A STUDY FOR THE PROPAGATION OF ELECTROMAGNETIC WAVES OVER IMPERFECT GROUND PLANES BASED ON SCHELKUNOFF INTEGRALS

A new formulation for the analysis of propagation of electromagnetic waves over imperfectly conducting planar surfaces is proposed. The classical approach for the analysis of this problem uses the Sommerfeld formulation. In Sommerfeld formulation, the wave function corresponding to a point source is expanded in terms of the propagation constants of the various waves in the radial direction from the source. This gives rise to the well-known Sommerfeld integrals which are highly oscillatory and slowly-decaying in nature, especially when the source is mounted just on top of a planar boundary between two media of arbitrary conductivity. In addition, the nature of the convergence for these integrals is extremely slow and may not yield stable results. In this dissertation we present an approach, developed originally by Schelkunoff, which expands the wave function in terms of the waves emanating perpendicular to the planar interface, not parallel to it as in Sommerfeld formulation. Expressions are given for both cases of vertical and horizontal electric dipoles on top of a planar interface. The debatable nature of this problem is unavoidable, thus a detailed analytical comparison between the Sommerfeld integrals and the expressions derived here is given. Based on the study given in this dissertation, the true rationale in relating the work of Zenneck and Sommerfeld to the relatively new field of surface plasmons is exposed. A detailed literature study as well as an analytical critique of the field of plasmonics and its relation to Sommerfeld-Zenneck surface waves is presented. Finally, some applications of the new formulation are discussed using numerical simulations

Numerical investigation of atmospheric icing on wind turbine blades

The research work presented in this thesis aims to predict ice accretion effect on a wind turbine blade section at 80% of blade span. All simulations are obtained using FENSAP ICE, a widely used solver for aircraft in-flight icing simulations. Using low and high liquid water concentrations existed in clouds at lower altitudes, different icing events are simulated. Ice accretion predictions are computed using single-shot and multi-shot approaches. Blade surface roughness is investigated, as well as the relationships between ice mass, liquid water content, median volume diameter and temperature are predicted. To study the effect of blade design / curvature parameters on the ice formation process, ice accretion loads are predicted for all NREL airfoil families used for horizontal axis wind turbines. The effect of low and high LWC conditions on blade thickness is presented. Effects of atmospheric temperature, LWC, MVD and flow angle of attack on resulted ice shape are investigated. The degradation in aerodynamic characteristics due to ice formation is investigated at different icing conditions. The new numerical data presented in this thesis provide useful insights on ice accretion rates for wind turbines operating in cold and harsh environments

ROLE OF THE SNF2 HOMOLOG, IRC20, IN YEAST GENOME MAINTENANCE

In eukaryotes, DNA is wrapped around histone proteins forming a highly compact structure, the chromatin. All DNA-based processes must occur within the complex organization of the chromatin, and this requires modulation of its structure when needed. This is accomplished by covalent histone modifications that alter histone-DNA contacts, as well as through the actions of ATP-dependent chromatin remodelers. These multi-subunit complexes play major roles in transcription regulation, replication and repairing DNA damage. This thesis aims to characterize a poorly studied member of the SWI/SNF family of ATPases/helicases, Irc20, from Saccharomyces cerevisiae. Previously, Irc20 has been shown to be involved in recombinational repair and to possess ubiquitin ligase (E3) activity. The human homolog of Irc20, SHPRH, has also been implicated in repair via the poly-ubiquitylation of PCNA, the sliding clamp of the DNA polymerase. Loss of heterozygosity in the region containing the SHPRH gene is seen in a wide variety of cancers. In this study, using purified Irc20, we showed that it possesses DNA and nucleosome binding activities, as well as an ATP-hydrolyzing activity. However, despite homology to Snf2 catalytic domain, Irc20 did not have the ability to alter chromatin structure. Using point mutations in different Irc20 domains, we identified that the increased recombination centers observed in irc20 null mutants is dependent on both its ATPase and ubiquitin ligase activities. Consistent with this, we observed higher recruitment or retention of the recombination repair factor Rad52 at a single induced double strand break in Δirc20 mutant, suggesting a regulatory role for Irc20 in DNA repair. Furthermore, we observed a previously unidentified function for Irc20 in regulating the levels of the endogenous yeast 2-μm plasmid. In irc20 null mutant, we observed a three to four-fold increase in 2-μm levels, forming high molecular weight forms in a manner dependent on homologous recombination. We suggest this is, at least partially, through regulating the levels of Flp1 recombinase since we observed higher levels of Flp1 in Δirc20 mutant after shutting off expression from a repressible promoter. Collectively, our results show a regulatory role for Irc20 in recombination underlying its role in stabilizing the genome and regulating the 2-μm plasmid levels

Scaling of multiphase flow, droplet trajectories, and ice accretion on a rotating wind turbine blade

This thesis presents an extended formulation of non-dimensionalized governing equations for scaling of the flow field, droplet trajectories, and ice accretion on a rotating wind turbine blade. The analytical formulation leads to similitude relationships for ice accretion to evaluate new scaling parameters corresponding to the rotation of the blade. The scaling methodology can be used to determine alternative test conditions and predict icing conditions on a full-scale wind turbine blade. The main objective of the research is to develop and apply scaling methods and similitude analyses for ice accretion prediction on a rotating turbine blade. The investigation reviews the derivation of the similitude relationships for ice accretion scaling to evaluate their importance and develops new scaling parameters corresponding to the rotation of the turbine blade. Numerical CFD icing simulations are also performed using ANSYS FENSAP ICE software to test the proposed scaling methods and verify the results. A turbine blade model is developed using blade element momentum theory (BEM). Turbine blade models are scaled up in geometry, and each case is tested at specific flow conditions as calculated using the scaling equations. Scaled conditions for velocity (streamwise and rotational), droplet size, and icing time are examined. CFD solutions for the flow field (air and droplet) are obtained in terms of velocity, droplet trajectories, pressure coefficient distributions, ice thickness, and ice shapes by quantifying the significant parameters involved in the icing process. Recommendations for parameters to be used for glaze and rime ice scaling on a rotating blade are presented and new numerical predictions are provided to support those recommendations. Numerical results and test conditions are obtained at sea level in wind tunnel facilities for experimental investigation. The research results provide valuable insight to predict ice accretion on large wind turbine blades in the field, based on smaller scaled blade models tested in a laboratory setting

Immunotherapy for B-Cell Neoplasms using T Cells expressing Chimeric Antigen Receptors : From antigen choice to clinical implementation

Immunotherapy with T cells expressing chimeric antigen receptors (CAR) is being evaluated as a potential treatment for B-cell neoplasms. In recent clinical trials it has shown promising results. As the number of potential candidate antigens expands, the choice of suitable target antigens becomes more challenging to design studies and to assess optimal efficacy of CAR. Careful evaluation of candidate target antigens is required to ensure that T cells expressing CAR will preferentially kill malignant cells with a minimal toxicity against normal tissues. B cells express specific surface antigens that can theoretically act as targets for CAR design. Although many of these antigens can stimulate effective cellular immune responses in vivo, their implementation in clinical settings remains a challenge. Only targeted B-cell antigens CD19 and CD20 have been tested in clinical trials. This article reviews exploitable B cell surface antigens for CAR design and examines obstacles that could interfere with the identification of potentially useful cellular targets

The Effect of Ownership Structure on Firm’s Financial Performance: An Empirical Study on the Most Active Firms in the Egyptian Stock Exchange

This paper seeks to examine the effect of ownership structure on firm financial performance in Egypt. Using a sample of 50 more active Egyptian companies listed on the Egyptian Stock Exchange of the non-financial sector covering the period of three financial years from 2007 to 2009. Ownership Structure is represented by Managerial Ownership, Institutional Ownership, Block holder Ownership and Free Float Ownership. Return on Assets (ROA) and Return on Equity (ROE) are used as a proxy for Firm financial Performance. Using multiple linear regressions as method of estimation, the results provide evidences that there is no significant relationship between ownership structure variables and firm financial performance measures by (ROA and ROE). This study provides many recommendations to the regulatory authorities in Egypt regarding ways to strengthen and reinforce the internal governance structure of companies especially ownership structure. Keywords: Corporate governance, Ownership structure, Firm Financial Performance, Egyp