He II optical depth and UV escape fraction of galaxies

We study the effect of H I ionizing photons escaping from high-redshift (high-z) galaxies have on the He II ionizing ultraviolet background (UVB) radiation. While these photons do not directly interact with He II ions, we show that they play an important role, through radiative transport, in modifying the shape of He II ionizing part of UVB spectrum. Within the observed range of UV escape from galaxies, we show that the rapid increase in He II Lyman alpha effective optical depth at z~2.7 can naturally be explained by radiative transport effects. Therefore, the relationship between a well measured He II Lyman alpha effective optical depth and the redshift in the post-He II reionization era can be used to place additional constraints on the redshift evolution of UV escape from high-z galaxies. Our study also suggests that the escape fraction of H I ionizing photons from galaxies has an important role in the fluctuations of the He II ionizing UVB.Comment: Published in MNRAS Letters, replacement of a figure and minor text changes corresponding to published versio

On the development computer, code for determinig the root of equation for transient flight analysis

This thesis presents the governing equation of flight motions which can be used to describe the flight behavior of any type flying vehicles consist of 12 equations described 12 state – space variables involving the aircraft position and aircraft aptitude with respect to the inertial coordinate system and also with respect to their axis body system had been used. These twelve equations are coupling each to others and in the forms highly non linear equation; the numerical approach is required for solving such system equation. The coefficient of system equation can be said as a result of the combination between aircraft’s mass and inertia, aircraft geometry properties and also their aircraft aerodynamics derivatives. The present work is focused in the development computer code which allows in manner of determining the root of equation of the 12 equations which described the flight behavior for particular airplane. Through determining the root of equation one will able to carry out a non linear transient analysis such as aircraft at landing approaches gust response and pilot initiated maneuvers

Development of cleaning procedures of copper corrosion products by using “green” deep eutectic solvents

Abstract: Selection and refinement of a method for copper corrosion removal were undertaken in an environmentally friendly way by using deep eutectic solvents (DES) integrated in a cellulose-based membrane. DES is a potential “green” solvent based on natural compounds. In this thesis, a DES composed of choline chloride and ascorbic acid in a 2:1 ratio, was prepared and used for copper corrosion cleaning. The DES was diluted with water and the DES to water ratio was optimized in terms of efficiency, time consumption, and selectivity of cleaning. It was found that DES solutions, having a concentration higher than 70 wt.% were suitable for dissolving copper corrosion products. Meanwhile, they exhibited a supressed dissolution ability of CaCO3 which is a common compound in many of the supporting structures used for copper artefacts. These solutions were then used for swelling cellulose membranes, and the swelling capacity was monitored for a week. The swollen membrane was put on an electrochemically corroded copper sheet for 24 hours. By removing the membrane, the green malachite layer was successfully removed from the copper sheet while preserving a reddish-brown cuprite layer. This was confirmed by performing X-ray diffraction analysis before and after cleaning the copper sample. For heritage objects, the defacing copper corrosion products of Cu (II) need to be removed apart from protective layer of cuprite. We concluded that the cellulose membranes containing DES solutions are promising materials for this purpose

Functional studies of phototaxis in Dictyostelium discoideum mutants

Abstract Dictyostelium discoideum has proven indispensable to elucidate cytoskeletal dynamics. The cytoskeleton plays a key role in almost all cellular processes, including motility, cytokinesis, cell-to-cell and cell-substrate adhesions and intracellular transport. Several actin binding proteins are also involved in these processes, among them are actin crosslinking proteins (for example, filamin and a-actinin). Filamin (also known as ddfilamin or gelation factor or ABP 120) consists of an actin binding domain and six rod repeats of 100 amino acids, its last repeat being responsible for the formation of the homodimer. Both the domains are necessary for the actin crosslinking activity of filamin. Dictyostelium mutants lacking filamin have severe defects in multicellular slug migration towards light, phototaxis, and preferable temperature, thermotaxis. To study the phototaxis defect in filamin- mutants at the molecular level we expressed various domains in the mutant and tested their rescue potential. Expression of C terminally truncated and point mutated (at a putative phosphorylation site) filamin rescued the phototaxis defect partially. Full-length filamin when expressed under the control of the ecmA promoter in the anterior tip of the slug rescues the phototaxis, but not when expressed under the control of the cotB promoter which allows expression in the posterior ¾th of the slug. Phototaxis is a complex phenomenon, which includes more than 55 genes. To identify genes involved in this process we carried out a microarray analysis. Amoung 65 genes we selected in microarray analysis, 40 genes were up regulated and 25 genes were down regulated. From the functions of most of theses genes, we conclude that the phototactic behaviour of slugs is controlled by extracellular cAMP, Ca2+ ions and cell adhesion. To further focus on filamin's function in phototaxis we searched for proteins interacting with filamin by a yeast two hybrid screen and by immunoprecipitation. TipA, GAPA and SapA proteins were pulled down in the immunoprecipitation approach while the FIP, filamin interacting protein, was found earlier in a yeast two hybrid screen. Biochemical studies suggest that FIP is associated with F-actin and may function in vesicle trafficking. Detailed analysis of the mutants of LIM proteins, villidin and filamin for chemotactic migration towards cAMP, led us to conclude that alteration in chemotactic motility of individual cells may not affect the phototactic migration of the slug