2,370 research outputs found

    PQL: A Declarative Query Language over Dynamic Biological Schemata

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    We introduce the PQL query language (PQL) used in the GeneSeek genetic data integration project. PQL incorporates many features of query languages for semi-structured data. To this we add the ability to express metadata constraints like intended semantics and database curation approach. These constraints guide the dynamic generation of potential query plans. This allows a single query to remain relevant even in the presence of source and mediated schemas that are continually evolving, as is often the case in data integration

    Mass study for modular approaches to a solar electric propulsion module

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    The propulsion module comprises six to eight 30-cm thruster and power processing units, a mercury propellant storage and distribution system, a solar array ranging in power from 18 to 25 kW, and the thermal and structure systems required to support the thrust and power subsystems. Launch and on-orbit configurations are presented for both modular approaches. The propulsion module satisfies the thermal design requirements of a multimission set including: Mercury, Saturn, and Jupiter orbiters, a 1-AU solar observatory, and comet and asteroid rendezvous. A detailed mass breakdown and a mass equation relating the total mass to the number of thrusters and solar array power requirement is given for both approaches

    A mechanical, thermal and electrical packaging design for a prototype power management and control system for the 30 cm mercury ion thruster

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    A prototype electric power management and thruster control system for a 30 cm ion thruster is described. The system meets all of the requirements necessary to operate a thruster in a fully automatic mode. Power input to the system can vary over a full two to one dynamic range (200 to 400 V) for the solar array or other power source. The power management and control system is designed to protect the thruster, the flight system and itself from arcs and is fully compatible with standard spacecraft electronics. The system is easily integrated into flight systems which can operate over a thermal environment ranging from 0.3 to 5 AU. The complete power management and control system measures 45.7 cm (18 in.) x 15.2 cm (6 in.) x 114.8 cm (45.2 in.) and weighs 36.2 kg (79.7 lb). At full power the overall efficiency of the system is estimated to be 87.4 percent. Three systems are currently being built and a full schedule of environmental and electrical testing is planned

    The Plasma Interaction Experiment (PIX) description and test program

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    The plasma interaction experiment (PIX) is a battery powered preprogrammed auxiliary payload on the LANDSAT-C launch. This experiment is part of a larger program to investigate space plasma interactions with spacecraft surfaces and components. The varying plasma densities encountered during available telemetry coverage periods are deemed sufficient to determine first order interactions between the space plasma environment and the biased experimental surfaces. The specific objectives of the PIX flight experiment are to measure the plasma coupling current and the negative voltage breakdown characteristics of a solar array segment and a gold plated steel disk. Measurements will be made over a range of surface voltages up to plus or minus kilovolt. The orbital environment will provide a range of plasma densities. The experimental surfaces will be voltage biased in a preprogrammed step sequence to optimize the data returned for each plasma region and for the available telemetry coverage

    Modular thrust subsystem approaches to solar electric propulsion module design

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    Three approaches are presented for packaging the elements of a 30 cm ion thruster subsystem into a modular thrust subsystem. The individual modules, when integrated into a conceptual solar electric propulsion module are applicable to a multimission set of interplanetary flights with the space shuttle interim upper stage as the launch vehicle. The emphasis is on the structural and thermal integration of the components into the modular thrust subsystems. Thermal control for the power processing units is either by direct radiation through louvers in combination with heat pipes or an all heat pipe system. The propellant storage and feed system and thruster gimbal system concepts are presented. The three approaches are compared on the basis of mass, cost, testing, interfaces, simplicity, reliability, and maintainability

    Privatization and Entrepreneurial Transformation

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    Privatization has become a popular strategy to promote economic development in developing, and developed economies. Despite its popularity, little attention has been devoted to examination of the organizational and managerial implications of privatization or to the effect of privatization on companies' ability to innovate and engage in entrepreneurial activities. this article we discuss privatization's increasing importance and present a model that links privatization to a firm's entrepreneurial activities. We conclude with a discussion of issues that we believe deserve scholars' attention in theory development and subsequent empirical examination.Publicad

    International survey of Cronobacter sakazakii and other Cronobacter spp. in follow up formulas and infant food

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    A coordinated survey for Cronobacter and related organisms in powdered infant formula, follow up formula and infant foods was undertaken by 8 laboratories in 7 countries in recognition of and in response to the data needs identified in an FAO/WHO call for data in order to develop global risk management guidance for these products. The products (domestic and imported) were purchased from the local market and were categorised according to their principle ingredients. A total of 290 products were analysed using a standardised procedure of pre-enrichment in 225 ml Buffered Peptone Water (BPW), followed by enrichment in Enterobacteriaceae Enrichment (EE) broth, plating on the chromogenic Cronobacter Druggan–Forsythe–Iversen (DFI) agar and presumptive identification with ID 32 E. Presumptive Cronobacter isolates were identified using 16S rRNA gene sequence analysis. Aerobic plate counts (APC) of the products were also determined on nutrient agar. Fourteen samples had APC > 105 cfu/g, 3 of which contained probiotic cultures. C. sakazakii was isolated from 27 products; 3/91 (3%) follow up formulas (as defined by Codex Alimentarius Commission), and 24/199 (12%) infant foods and drinks. Hence C. sakazakii was less prevalent in follow up formula than other foods given to infants over the same age range. A range of other bacteria were also isolated from follow up formulas, including Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumoniae, Citrobacter freundii, and Serratia ficaria. There was significant variation in the reconstitution instructions for follow up formulas. These included using water at temperatures which would enable bacterial growth. Additionally, the definition of follow up formula varied between countries

    Study of microRNAs-21/221 as potential breast cancer biomarkers in Egyptian women

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    microRNAs (miRNAs) play an important role in cancer prognosis. They are small molecules, approximately 17–25 nucleotides in length, and their high stability in human serum supports their use as novel diagnostic biomarkers of cancer and other pathological conditions. In this study, we analyzed the expression patterns of miR-21 and miR-221 in the serum from a total of 100 Egyptian female subjects with breast cancer, fibroadenoma, and healthy control subjects. Using microarray-based expression profiling followed by real-time polymerase chain reaction validation, we compared the levels of the two circulating miRNAs in the serum of patients with breast cancer (n = 50), fibroadenoma (n = 25), and healthy controls (n = 25). The miRNA SNORD68 was chosen as the housekeeping endogenous control. We found that the serum levels of miR-21 and miR-221 were significantly overexpressed in breast cancer patients compared to normal controls and fibroadenoma patients. Receiver Operating Characteristic (ROC) curve analysis revealed that miR-21 has greater potential in discriminating between breast cancer patients and the control group, while miR-221 has greater potential in discriminating between breast cancer and fibroadenoma patients. Classification models using k-Nearest Neighbor (kNN), Naïve Bayes (NB), and Random Forests (RF) were developed using expression levels of both miR-21 and miR-221. Best classification performance was achieved by NB Classification models, reaching 91% of correct classification. Furthermore, relative miR-221 expression was associated with histological tumor grades. Therefore, it may be concluded that both miR-21 and miR-221 can be used to differentiate between breast cancer patients and healthy controls, but that the diagnostic accuracy of serum miR-21 is superior to miR-221 for breast cancer prediction. miR-221 has more diagnostic power in discriminating between breast cancer and fibroadenoma patients. The overexpression of miR-221 has been associated with the breast cancer grade. We also demonstrated that the combined expression of miR-21 and miR-221can be successfully applied as breast cancer biomarkers

    Primary Intraocular Lymphoma

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    Sinteza, protuupalno, analgetsko i antikonvulzivno djelovanje 1,8-dihidro-1-aril-8-alkil pirazolo(3,4-b)indola

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    A series of 1,8-dihydro-1-aryl-8-alkyl pyrazolo(3,4-b)indoles 4a-j, 5a-j and 6a-j has been synthesized and tested for their anti-inflammatory and anticonvulsant activities. Formation of the pyrazoloindole derivatives was achieved by treating arylhydrazones of N-alkyl indole-3-carboxaldehydes 1a-j, 2a-j and 3a-j with ten times their mass of polyphosphoric acid as a condensing agent. The newly synthesized compounds were evaluated for their anti-inflammatory, analgesic and anticonvulsant activities compared to indomethacin, flufenamic acid and diazepam as positive controls. Detailed synthesis, spectroscopic and toxicity data are reported.Serija 1,8-dihidro-1-aril-8-alkil pirazolo(3,4-b)indola 4a-j, 5a-j i 6a-j sintetizirana je i testirana na protuupalno i antikonvulzivno djelovanje. Pirazolindol derivati pripravljeni su reakcijom arilhidrazona N-alkil indol-3-karboksaldehida 1a-j, 2a-j i 3a-j s deset puta većom masom polifosforne kiseline kao sredstva za kondenzaciju. Novosintetizirani spojevi testirani su na protuupalno, analgetsko i antikonvulzivno djelovanje i uspoređeni s djelovanjem indometacina, flufenaminske kiseline i diazepama. U radu su dati detaljni sintetski, spektroskopski i toksikološki podaci
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