3,361 research outputs found

    Schemes of implementation in NMR of quantum processors and Deutsch-Jozsa algorithm by using virtual spin representation

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    Schemes of experimental realization of the main two qubit processors for quantum computers and Deutsch-Jozsa algorithm are derived in virtual spin representation. The results are applicable for every four quantum states allowing the required properties for quantum processor implementation if for qubit encoding virtual spin representation is used. Four dimensional Hilbert space of nuclear spin 3/2 is considered in details for this aimComment: 15 pages, 3 figure

    Design of prototype charged particle fog dispersal unit

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    The unit was designed to be easily modified so that certain features that influence the output current and particle size distribution could be examined. An experimental program was designed to measure the performance of the unit. The program described includes measurements in a fog chamber and in the field. Features of the nozzle and estimated nozzle characteristics are presented

    Feasibility study of a procedure to detect and warn of low level wind shear

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    A Doppler radar system which provides an aircraft with advanced warning of longitudinal wind shear is described. This system uses a Doppler radar beamed along the glide slope linked with an on line microprocessor containing a two dimensional, three degree of freedom model of the motion of an aircraft including pilot/autopilot control. The Doppler measured longitudinal glide slope winds are entered into the aircraft motion model, and a simulated controlled aircraft trajectory is calculated. Several flight path deterioration parameters are calculated from the computed aircraft trajectory information. The aircraft trajectory program, pilot control models, and the flight path deterioration parameters are discussed. The performance of the computer model and a test pilot in a flight simulator through longitudinal and vertical wind fields characteristic of a thunderstorm wind field are compared

    Invasion of a Virulent Phytophthora infestans Genotype at the Landscape Level; Does Spatial Heterogeneity Matter?

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    Proper landscape-scale deployment of disease resistant genotypes of agricultural crop species could make those crops less vulnerable to invasion by resistance breaking genotypes. Here we develop a multi-scale, spatiotemporal model of the potato late blight pathosystem to investigate spatial strategies for the deployment of host resistance. This model comprises a landscape generator, a potato late blight model, and a suite of aerobiological models, including an atmospheric dispersion model. Within individual growing regions, increasing the number of host genotypes caused the greatest reduction in epidemic extent, followed by reduction of the proportion of potato in the landscape, lowering the clustering of host fields, and reducing the size of host fields. Deployment of host resistance in genotype mixtures had a large effect on disease invasion. The use of space as an isolation barrier was effective in scenarios involving two distinct potato growing regions. It was possible to completely eliminate the risk of epidemic spread from one region to another using inter-regional separation distances ranging from 8 to 32 km. The overall efficacy of this strategy was highly dependent, however, on the degree of spatial mixing of potato genotypes within each region. Deployment of host resistance in genotype mixtures in both regions served to reduce the overall level of incidence in the landscape and the inter-regional separation distance required to eliminate relevant levels of between-region spread of diseas

    Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

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    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail

    Regional spore dispersal as a factor in disease risk warnings for potato late blight: a proof of concept

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    This study develops and tests novel approaches that significantly reduce the fungicide input necessary for potato late blight control while maintaining the required high level of disease control. The central premise is that fungicide inputs can be reduced by reducing dose rates on more resistant cultivars, by omitting applications on days when conditions are unsuitable for atmospheric transport of viable sporangia and by adapting the dose rate to the length of the predicted critical period. These concepts were implemented and tested in field experiments in 2007 and 2008 in the North Eastern potato growing region in the Netherlands which is known for its high potato late blight disease pressure. Field experiments contained three starch potato cultivars, representing a range in resistance to potato late blight from susceptible to highly resistant, and a series of decision rules determining spray timing and incorporating an increasing number of variables such as: remaining fungicide protection level, critical weather, atmospheric capacity for viable transport of sporangia and the length of the predicted critical period. The level of cultivar resistance was used to reduce the dose rate of the preventive fungicide Shirlan (a.i. fluazinam) by default. A 50% – 75% reduction of the fungicide input proved possible in both years without adverse consequences to the crop or yield. The principles can be used in many decision contexts, but further work is needed to test and refine the methods before it can be used in practic

    Interplay between gut bacteria and Parkinson’s disease medication

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    Parkinson’s disease (PD) is a neurodegenerative disorder, which affects approximately 6 million individuals worldwide. The main pathologic feature observed in PD patients is the abnormal aggregation of protein and loss of dopaminergic neurons in the midbrain, resulting in motor deficits. Levodopa remains the “golden” standard treatment to restore the absence of dopamine in the brain. Although the start of levodopa treatment has an optimal efficacy, the progression of the disease causes a high variability in the efficacy of levodopa treatment among patients resulting in an unstable and unpredictable clinical response; motor-fluctuations. Besides motor deficits, PD patients also experience various non-motor symptoms such as gastrointestinal dysfunction. In this thesis, we showed that gut bacteria can contribute to the reduction of levodopa availability in the blood-circulation and that they can metabolize the unabsorbed residues of levodopa to various products that alter the gut motility. Furthermore, we showed that the most commonly used PD medications per se may affect the small intestinal motility, the main site of drug absorption, thereby altering the microbiota composition. Such events will potentially create a vicious cycle among the microbiota, PD medication, and gastrointestinal function, and urges for consideration of PD medication and gastrointestinal function when assessing alterations in the PD-associated microbiota. Finally, determining the clinical impact of gut bacteria on PD medication will help reduce the factors contributing to compromised levodopa bioavailability and the unwarranted side effects that result potentially in and from increased treatment regimen

    Murine developmental control genes.

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    Various strategies have been used to isolate genes that participate in the regulation of mouse development. Gene families that have been identified on the basis of their homology to motifs within Drosophila control genes or human transcription factor genes, namely homeobox (Hox), paired-box (Pax), and POU genes, can be compared with respect to gene organization, structure, and expression patterns. The functions of these genes can be analyzed molecularly in vitro and in vivo with the use of available mouse mutants or transgenic mice. In addition, it has been possible to generate gain- or loss-of-function mutations by random or targeted introduction of transgenes. Models derived from these studies can reveal the successive steps of developmental control on a genetic level

    Proximity Induced Superconductivity in CdTe-HgTe Core-Shell Nanowires

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    In this letter we report on proximity superconductivity induced in CdTe-HgTe core-shell nanowires, a quasi-one-dimensional heterostructure of the topological insulator HgTe. We demonstrate a Josephson supercurrent in our nanowires contacted with superconducting Al leads. The observation of a sizable IcRnI_c R_n product, a positive excess current and multiple Andreev reflections up to fourth order further indicate a high interface quality of the junctions.Comment: Accepted for publication in Nano Letter
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