11,829 research outputs found

    Unconditional quantum cloning of coherent states with linear optics

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    A scheme for optimal Gaussian cloning of optical coherent states is proposed and experimentally demonstrated. Its optical realization is based entirely on simple linear optical elements and homodyne detection. The optimality of the presented scheme is only limited by detection inefficiencies. Experimentally we achieved a cloning fidelity of about 65%, which almost touches the optimal value of 2/3.Comment: Phys. Rev. Lett. Volume 94, Number 24, p. 24050

    Mollusca of the Illinois River, Arkansas

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    The Illinois River is in the Ozark region of northwestern Arkansas and eastern Oklahoma. A survey of the Illinois River in Arkansas produced nine species and one morphological subspecies of gastropods, three species of sphaeriid clams, and 23 species of unionid mussels. Museum records resulted in another two species and an ecophenotype of the Unionidae. This represents the first published survey of molluscan species from the Illinois River in Arkansas

    OPTIMAL SPATIAL ALLOCATION OF WASTE MANAGEMENT PRACTICES TO REDUCE PHOSPHORUS POLLUTION IN A WATERSHED

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    Phosphorus pollution from excessive litter application and municipal discharges causes eutorphication of lakes in the Eucha-Spavinaw watershed in eastern Oklahoma and western Arkansas. Consequent algae blooms impair the taste of drinking water supply drawn from the watershed and reduce the recreational values of the lakes. The paper shows how GIS data based biophysical modeling can be used to derive spatially optimal, least-cost allocation of agricultural management practices to be combined with optimal wastewater treatment activity from the point source in order to achieve socially optimal phosphorus load in the watershed. The optimal level of phosphorus load is determined by equating marginal abatement with marginal damage cost. Transportation activities in the model allow for transportation of litter within and out of the watershed. Results show uniform regulation of litter application is excessively costly relative to measures that encourage adoption of management practices that equate marginal abatement costs across pollution sources. The results also show that change in the land use patterns in a long-run and using alum based litter additives in short-run are economically efficient management options.Environmental Economics and Policy,

    Entrepreneurship and SMEs through business incubators in the Arab world: case study of Jordan

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    Business incubators (BI) have proved to be effective tools for looking after Entrepreneurship and SMEs to tackling unemployment, diversifying economies and creating wealth in numerous developed countries. By providing timely help and support for new ventures, business incubators hold the potential to create and develop entrepreneurial talent at the micro level and foster an environment for entrepreneurship at the macro level. This research aimed to determine whether the economic conditions for business strategy in the Arab World are favourable to a programme of business incubation and to suggest directions on the best ways to implement more business incubation in the Arab countries. To meet this aim the study undertook a snowball approach and distributed a designed questionnaire to the incubation unites in Jordan. The findings of the research contribute to the literature of business support services, innovation and entrepreneurship development and will enhance the knowledge and skills within the incubation industry. The centre’s incubator programme is designed to accelerate the successful development of young entrepreneurs and their businesses

    The superficial brachial artery : a case report

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    A superficial brachial artery is an anomalous branch of the brachial artery that runs superficial to the median nerve; it is usually associated with a deep brachial branch that runs deep to this nerve. A case is described of a superficial brachial artery. It is of the type where the artery terminates in the cubital fossa by division into radial and ulnar arteries. It is associated with a superficial ulnar artery, and a deep brachial artery that is continued into the forearm as the common interosseous artery, a rare occurrence. The clinical importance and the dangers of this vascular anomaly are discussed. In reparative surgery, an accurate knowledge of the relationship, course and particularly the possible variations of the brachial artery is of considerable importance.peer-reviewe

    A Complex Chemical Potential: Signature of Decay in a Bose-Einstein Condensate

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    We explore the zero-temperature statics of an atomic Bose-Einstein condensate in which a Feshbach resonance creates a coupling to a second condensate component of quasi-bound molecules. Using a variational procedure to find the equation of state, the appearance of this binding is manifest in a collapsing ground state, where only the molecular condensate is present up to some critical density. Further, an excited state is seen to reproduce the usual low-density atomic condensate behavior in this system, but the molecular component is found to produce an underlying decay, quantified by the imaginary part of the chemical potential. Most importantly, the unique decay rate dependencies on density (ρ3/2\sim \rho ^{3/2}) and on scattering length (a5/2\sim a^{5/2}) can be measured in experimental tests of this theory.Comment: 4 pages, 1 figur

    Decoding the Encoding of Functional Brain Networks: an fMRI Classification Comparison of Non-negative Matrix Factorization (NMF), Independent Component Analysis (ICA), and Sparse Coding Algorithms

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    Brain networks in fMRI are typically identified using spatial independent component analysis (ICA), yet mathematical constraints such as sparse coding and positivity both provide alternate biologically-plausible frameworks for generating brain networks. Non-negative Matrix Factorization (NMF) would suppress negative BOLD signal by enforcing positivity. Spatial sparse coding algorithms (L1L1 Regularized Learning and K-SVD) would impose local specialization and a discouragement of multitasking, where the total observed activity in a single voxel originates from a restricted number of possible brain networks. The assumptions of independence, positivity, and sparsity to encode task-related brain networks are compared; the resulting brain networks for different constraints are used as basis functions to encode the observed functional activity at a given time point. These encodings are decoded using machine learning to compare both the algorithms and their assumptions, using the time series weights to predict whether a subject is viewing a video, listening to an audio cue, or at rest, in 304 fMRI scans from 51 subjects. For classifying cognitive activity, the sparse coding algorithm of L1L1 Regularized Learning consistently outperformed 4 variations of ICA across different numbers of networks and noise levels (p<<0.001). The NMF algorithms, which suppressed negative BOLD signal, had the poorest accuracy. Within each algorithm, encodings using sparser spatial networks (containing more zero-valued voxels) had higher classification accuracy (p<<0.001). The success of sparse coding algorithms may suggest that algorithms which enforce sparse coding, discourage multitasking, and promote local specialization may capture better the underlying source processes than those which allow inexhaustible local processes such as ICA

    Economic Analysis of Management Practices to Reduce Phosphorus Load to Lake Eucha and Spavinaw

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    Changes in management practices are often proposed to reduce phosphorus loading from a watershed due to over application of poultry litter. This study determines the choice, location, and level of each best management practice in the watershed to meet a Total Maximum Daily Load and margins of safety at least cost.best management practice, phosphorus runoff, poultry litter, Target MOTAD, Environmental Economics and Policy,
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