Role of the host cell in bacteriophage T4 development. II. Characterization of host mutants that have pleiotropic effects on T4 growth

Mutant host-defective Escherichi coli that fail to propagate bacteriophage T4 and have a pleiotropic effect on T4 development have been isolated and characterized. In phage-infected mutant cells, specific early phage proteins are absent or reduced in amount, phage DNA synthesis is depressed by about 50%, specific structural phage proteins, including some tail and collar components, are deficient or missing, and host-cell lysis is delayed and slow. Almost all phage that can overcome the host block carry mutantions that map in functionally undefined 'nonessential' regions of the T4 genome, most near gene 39. The mutant host strains are temperature sensitive for growth and show simultaneous reversion of the ts phenotype and the inability to propagate T4+. The host mutations are cotransduced with ilv (83 min) and may lie in the gene for transcription termination factor rho

Transition to turbulence in Hunt's flow in a moderate magnetic field

Pressure-driven magnetohydrodynamic duct flow in a transverse uniform magnetic field is studied by direct numerical simulation. The electric boundary conditions correspond to Hunt's flow with perfectly insulating walls parallel to the magnetic field (sidewalls) and perfectly conducting walls perpendicular to the magnetic field (Hartmann walls). The velocity distribution exhibits strong jets at the sidewalls, which are susceptible to instability even at low Reynolds numbers Re. We explore the onset of time-dependent flow and transition to states with evolved turbulence for a moderate Hartmann number $Ha = 100$ . At low Re time-dependence appears in the form of elongated Ting-Walker vortices at the sidewalls of the duct, which, upon increasing Re, develop into more complex structures with higher energy and then the sidewall jets partially detach from the walls. At high values of Re jet detachments disappear and the flow consists of two turbulent jets and nearly laminar core. It is also demonstrated that, there is a range of Re, where Hunt's flow exhibits a pronounced hysteresis behavior, so that different unsteady states can be observed for the same flow parameters. In this range multiple states may develop and co-exist, depending on the initial conditions

Magnetic Field Saturation in the Riga Dynamo Experiment

After the dynamo experiment in November 1999 had shown magnetic field self-excitation in a spiraling liquid metal flow, in a second series of experiments emphasis was placed on the magnetic field saturation regime as the next principal step in the dynamo process. The dependence of the strength of the magnetic field on the rotation rate is studied. Various features of the saturated magnetic field are outlined and possible saturation mechanisms are discussed.Comment: 4 pages, 8 figure

History and results of the Riga dynamo experiments

On 11 November 1999, a self-exciting magnetic eigenfield was detected for the first time in the Riga liquid sodium dynamo experiment. We report on the long history leading to this event, and on the subsequent experimental campaigns which provided a wealth of data on the kinematic and the saturated regime of this dynamo. The present state of the theoretical understanding of both regimes is delineated, and some comparisons with other laboratory dynamo experiments are made.Comment: 8 pages, 5 figure, accepted for publication in Comptes Rendus Physiqu

Detection of a flow induced magnetic field eigenmode in the Riga dynamo facility

In an experiment at the Riga sodium dynamo facility, a slowly growing magnetic field eigenmode has been detected over a period of about 15 seconds. For a slightly decreased propeller rotation rate, additional measurements showed a slow decay of this mode. The measured results correspond satisfactory with numerical predictions for the growth rates and frequencies

A comparison between the chemical behaviour of lead-gold and lead-bismuth eutectics towards 316L stainless steel

Lead-gold eutectic (LGE) has been recently proposed as an alternative target material for high power spallation sources. In order to compare the corrosive properties of LGE to the better-studied eutectic of lead-bismuth (LBE), an isothermal twin-loop made of SS 316L was built and operated at the Institute of Physics of the University of Latvia. We have measured the concentration of steel alloying elements dissolved in both alloys at the end of two test campaigns via ICP-OES. In case of LGE, a pronounced concentration increase of Fe, Ni, Mn and Cr is found in the liquid metal, which is significantly higher compared to LBE. Similar results were obtained during complementary investigations on material samples exposed to both alloys in this twin-loop at 400 ◦C and 450 ◦C. These findings indicate that in contact with LGE, SS 316L steel suffers from substantial chemical attack. Detailed investigations using structure materials other than SS 316L have to be undertaken before qualifying LGE as a serious alternative to LB

Financial analysis of SIA "Trīs A Brokers"

Diplomdarba temats ir “SIA “Trīs A brokers” finanšu analīze”. Darba mērķis ir uz finanšu analīzes teorijas pamata, veikt SIA „Trīs A brokers” finansiālā stāvokļa novērtējumu un sniegt secinājumus, kā arī priekšlikumus par uzņēmuma finanšu darbības uzlabošanu. Darba gaitā teorētiskajā daļā apskatīti finanšu analīzes teorētiskie aspekti, kuri sastāv no, finanšu koeficientu analīzes, kā arī no apgrozāmo līdzekļu analīzes. Praktiskajā daļā autors veica uzņēmuma gada pārskatu analīzi par 2005., 2006. un 2007. gadu, novērtējot uzņēmuma finanšu stāvokļa izmaiņas analizējamo periodu laikā, un mēģinot noteikt to izmaiņu cēloņus, kā arī veica finanšu analīzi ar mērķi uzlabot un pilnveidot uzņēmuma finanšu darbību. Turpinājumā autors veica uzņēmuma finanšu analīzi aprēķinot likviditātes, maksātspējas, aktivitātes un rentabilitātes rādītājus. Šajā nodaļā autors izteica piedāvājumu finanšu situācijas uzlabošanai, kuru varētu izmantot analizētā uzņēmuma vadība turpmāko finanšu lēmumu pieņemšanā. Pēc veiktajiem finanšu analīzes aprēķiniem, autors darbā ir secinājis, ka uzņēmums SIA „Trīs A brokers” ir finansiāli stabils, ar sabalansētu bilances struktūru, bez īstermiņa sagaidāmām finansiālām problēmām. Tomēr, ir vērojama neto peļņas samazināšanās, lai no tā izvairītos, autors iesaka uzņēmuma vadībai, palielināt neto apgrozījumu gan motivējot esošos darbiniekus jaunu klientu piesaistē, gan arī pieņemot darbā jaunus, jau pieredzējušus apdrošināšanas brokerus. Diplomdarba apjoms ir 60 lappuses. Darbs sastāv no trīs nodaļām un sešiem pielikumiem. Darbā tika izmantotas 18 tabulas, 8 attēli un 23 formulasThe title of the diploma work is “Financial analysis of “Trīs A Brokers”Ltd.” The assessment of financial situation of the enterprise is the basis of its right management and provision of future perspectives, therefore the author decided to research the financial situation of the enterprise and to work out suggestions for improvement. The theoretical aspects of financial analysis are surveyed in the theoretical part and it consists of horizontal and vertical analysis of financial statements, analysis of financial coefficients, as well as the analysis of cash flow. In practical part the author carries out the analysis of annual reports of the years 2005. 2006., and 2007., evaluating the changes of financial position during the period of analysis and trying to determine the reasons of changes, as well as fulfils the financial analysis aimed to improve and upgrade the financial activities of the enterprise. In continuation the author performs the financial analysis of the enterprise, calculating the indices of liquidity, paying capacity, activity and profitability, and. In this part the author gives his suggestions of improvement of financial situation, what could be used by the head of the analyzed enterprise in order to make the further financial decisions. The amount of the diploma work is 60 pages, consisting of 3 parts and six supplements. 18 tables, 8 pictures and 23 formulas are used in this work

Revised Location of the rIII Gene on the Genetic Map of Bacteriophage T4

Two- and three-factor crosses showed that the T4 rIII gene is located between genes 31 and 30 rather than between genes 31 and 63