Availability analysis of the traveling-wave maser amplifiers in the deep space network. Part 1: The 70-meter antennas

The results of the reliability and availability analyses of the individual S- and X-band traveling-wave maser (TWM) assemblies and their operational configurations in the 70-meter antennas of NASA's Deep Space Network (DSN) are described. For the period 1990 through 1991, the TWM availability parameters for the Telemetry Data System are: mean time between failures (MTBF), 930 hr; mean time to restore services (MTTRS), 1.4 hr; and the average availability, 99.85 percent. In previously published articles, the performance analysis of the TWM assemblies was confined to the determination of the parameters specified above. However, as the mean down time (MDT) for the repair of TWM's increases, the levels of the TWM operational availabilities and MTTRS are adversely affected. A more comprehensive TWM availability analysis is presented to permit evaluation of both MTBF and MDT effects. Performance analysis of the TWM assemblies, based on their station monthly failure reports, indicates that the TWM's required MTBF and MDT levels of 3000 hr and 36 to 48 hr, respectively, have been achieved by the TWM's only at the Canberra Deep Space Station (DSS 43). The Markov Process technique is employed to develop suitable availability measures for the S- and X-band TWM configurations when each is operated in a two-assembly standby mode. The derived stochastic expressions allow for the evaluation of those configurations' simultaneous availability for the Antenna Microwave Subsystem. The application of these expressions to demonstrate the impact of various levels of TWM maintainability (or MDT) on their configurations' operational availabilities is presented for each of the 70-m antenna stations

Isolation of Trichophyton mentogrophytes var mentogrophytes from naturally infected laboratory albino rats: experimental infection and treatment in rabbits

The present study demonstrated for the first time the occurrence of dermatophytosis in naturally infected rats and from asymptomatic and from breeding boxes of white rats kept in animal housing of college of Veterinary Medicine, University of Dohuk, Iraq. The prevalence rate of infection was (28%), clinically infected rats characterized by appearance of scaly ovoid type lesions with crusty edge and patch of hair loss mostly seen on the back, neck and face of the infected rats, itching was reported in some rats. Only one species of the trichophyton, T. mentogrophytes var mentogrophytes was isolated with growth rate (85.71%) of samples collected from clinically infected rats, and (28.57%) from asymptomatic and from breeding cages, the growth was observed within the 21 days at 25ºC on Sabouraud's Dextrose Agar. Lacto phenol cotton blue staining slides of T. mentogrophytes var mentogrophytes revealed both microconidia and macroconidia. Microconidia found in numerous numbers often in dense cluster which were hyaline, smooth walled and predominantly spherical to sub spherical in shape, varying numbers of chlamydoconidia. Spiral hyphae and smooth, thin walled clavate shaped multicelled macroconidia were also present. The study also dealt with experimental infection in rabbits with T. mentogrophytes var mentogrophytes and treated by two drugs, natural herbal preparation of acidic pomegranate (Punica granatum) fruit and synthetic nystatine ointment. The complete recovery of lesions was recorded after 14 days and 21 days of topical application of a pomegranate and nystatine ointment for 5 successive days respectively

First report of Metarhizium anisopliae IP 46 pathogenicity in adult Anopheles gambiae s.s. and An. arabiensis (Diptera; Culicidae).

The entomopathogenic fungus Metarhizium anisopliae isolate IP 46, originating from a soil sample collected in 2001 in the Cerrado of Central Brazil, was tested for its ability to reduce the survival of adult male and female Anopheles gambiae s.s. and An. arabiensis mosquitoes. A 6-h exposure to the fungus coated on test paper at a concentration of 3.3 x 106 conidia cm-2 reduced the daily survival of both mosquito species (HR = 3.14, p < 0.001), with higher risk of dying in An. gambiae s.s relative to An. arabiensis (HR = 1.38, p < 0.001). Fungal sporulation was observed in >95% of mosquito cadavers in the treatment groups. The results indicate that M. anisopliae IP 46 has the potential to be a bio-control agent for African malaria vector species, and is a suitable candidate for further research and development

Pinwheel stabilization by ocular dominance segregation

We present an analytical approach for studying the coupled development of ocular dominance and orientation preference columns. Using this approach we demonstrate that ocular dominance segregation can induce the stabilization and even the production of pinwheels by their crystallization in two types of periodic lattices. Pinwheel crystallization depends on the overall dominance of one eye over the other, a condition that is fulfilled during early cortical development. Increasing the strength of inter-map coupling induces a transition from pinwheel-free stripe solutions to intermediate and high pinwheel density states.Comment: 10 pages, 4 figure

Entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana reduce the survival of Xenopsylla brasiliensis larvae (Siphonaptera: Pulicidae).

Entomopathogenic fungi, particularly those belonging to the genera Metarhizium and Beauveria have shown great promise as arthropod vector control tools. These agents, however, have not been evaluated against flea vectors of plague. A 3-h exposure to the fungi coated paper at a concentration of 2 × 108 conidia m-2 infected >90% of flea larvae cadavers in the treatment groups. The infection reduced the survival of larvae that had been exposed to fungus relative to controls. The daily risk of dying was four- and over three-fold greater in larvae exposed to M. anisopliae (HR = 4, p<0.001) and B. bassiana (HR = 3.5, p<0.001) respectively. Both fungi can successfully infect and kill larvae of X. brasiliensis with a pooled median survival time (MST±SE) of 2±0.31 days post-exposure. These findings justify further research to investigate the bio-control potential of entomopathogenic fungi against fleas.\ud \u

Analysis of soil texture using terrasar x-band sar

International audienceIn this paper, it is proposed to use TERRASAR-X data for analysis and estimation of soil surface texture. Our study is based on experimental campaigns carried out over a semi-arid area in North Africa. Simultaneously to TERRASAR-X radar acquisitions, ground measurements (texture, soil moisture and roughness) were made on different test fields. A strong correlation is observed between soil texture and a processed signal from two radar images, the first acquired just after a rain event and the second corresponding to dry soil conditions, acquired three weeks later. An empirical relationship is proposed for the retrieval from radar signals of clay content percent. Soil texture mapping is proposed over the study site, which includes bare soils and olive groves

Synthesis and spectral studies of 5-[3-(1,2,4-triazolyl-azo]-2,4-dihydroxybenzaldehyde(TA)and its Schiff bases with 1,3-diaminopropane(TAAP)and 1,6-diaminohexane(TAAH).Their analytical application for spectrophotometric microdetermination of cobalt(II).

Cataloged from PDF version of article.The new azo compound 5-[3-(1,2,4-triazolyl-azo]-2,4-dihydroxy-benzaldehyde (TA) and its Schiff bases with 1,3-diaminopropane (TAAP) and 1,6-diaminohexane (TAAH) have been synthesized. The bands of diagnostic importance in the IR and the main signals in 1 H NMR spectra are assigned. The electronic absorption spectra in pure organic solvents of different polarity and in buffer solutions of varying pH are investigated. The quantitative description of the solvent effect on the electronic absorption spectra is studied and their acid ionization constants are determined. Also, a new simple and sensitive method for the spectrophotometric microdetermination of Co(II) using these compounds (TA, TAAP and TAAH) as new chromogenic reagents is established. The developed method is successfully used for the determination of trace amounts of cobalt in authentic samples and calculation of the distribution ratio of cobalt adsorbed on bentonite and kaolinite clay minerals. 2004 Elsevier Ltd. All rights reserved