15,587 research outputs found

    On a three-body confinement force in hadron spectroscopy

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    Recently it has been argued that a three-body colour confinement interaction can affect the stability condition of a three-quark system and the spectrum of a tetraquark described by any constituent quark model. Here we discuss the role of a three-body colour confinement interaction in a simple quark model and present some of its implications for the spectra of baryons, tetraquarks and six-quark systems.Comment: 19 pages (RevTeX), addition of new material regarding the NN interaction, more accurate discussion of the baryonic case, accepted for publication in Phys. Rev.

    Skyrme density functional description of the double magic 78^{78}Ni nucleus

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    We calculate the single particle spectrum of the double magic nucleus 78^{78}Ni in a Hartree-Fock approach using the Skyrme density-dependent effective interaction containing central, spin-orbit and tensor parts. We show that the tensor part has an important effect on the spin-orbit splitting of the proton 1f1f orbit which may explain the survival of magicity so far from the stability valley. We confirm the inversion of the 1f5/21f5/2 and 2p3/22p3/2 levels at the neutron number 48 in the Ni isotopic chain expected from previous Monte Carlo shell model calculations and supported by experimental observation.Comment: 14 pages, 5 figures, typos corrected. arXiv admin note: text overlap with arXiv:nucl-th/070206

    NN interaction in a Goldstone boson exchange model

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    Adiabatic nucleon-nucleon potentials are calculated in a six-quark nonrelativistic chiral constituent quark model where the Hamiltonian contains a linear confinement and a pseudoscalar meson (Goldstone boson) exchange interaction between quarks. Calculations are performed both in a cluster model and a molecular orbital basis, through coupled channels. In both cases the potentials present an important hard core at short distances, explained through the dominance of the [51]_{FS} configuration, but do not exhibit an attractive pocket. We add a scalar meson exchange interaction and show how it can account for some middle-range attraction.Comment: 32 pages with 12 eps figures incorporated, RevTeX. Final version published in PR

    How Dysarthric Prosody Impacts Naïve Listeners’ Recognition

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    The class of speech disorders known as dysarthria arise from disturbances in muscular control over the speech mechanism caused by damage of the central or peripheral nervous system. Dysarthria is typically classified into one of six classes, each corresponding to a different neurological disorder with distinct prosodic cues [3]. The assumption in this classification is that dysarthric speech can be classified implicit on the basis of perception. In this study, we investigate how accurately naïve listeners can recognize stress and intonation in dysarthric speech, and if different neurological disorders impact the ability to convey meaning with these same two cues. To those ends, we collected speech data from Dutch speakers diagnosed with cerebellar lesions (ataxic dysarthria), Parkinson’s Disease (hypokinetic dysarthria), Multiple Sclerosis (mixed classes of dysarthria) and from a healthy control group. Thirteen naïve Dutch listeners participated in the perceptual experiment which targeted recognition of intended realization of four prosodic functions: lexical stress, sentence type, boundary marking and focus. We analyzed recognition accuracy for different groups and performed acoustic analyses to check for fundamental frequency trajectories. Results attest to different accuracy recognition results for different disease groups. The sentence type recognition task was the most sensitive of all tasks for differentiating different diseases both on perceptual and acoustic levels of analysis.</p

    New Baryons in the Delta eta and Delta omega Channels

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    The decays of excited nonstrange baryons into the final states Delta eta and Delta omega are examined in a relativized quark pair creation model. The wavefunctions and parameters of the model are fixed by previous calculations of N pi and N pi pi, etc., decays through various quasi-two body channels including N eta and N omega. Our results show that the combination of thresholds just below the region of interest and the isospin selectivity of these channels should allow the discovery of several new baryons in such experiments.Comment: 10 pages, RevTe

    Strange Decays of Nonstrange Baryons

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    The strong decays of excited nonstrange baryons into the final states Lambda K, Sigma K, and for the first time into Lambda(1405) K, Lambda(1520) K, Sigma(1385) K, Lambda K*, and Sigma K*, are examined in a relativized quark pair creation model. The wave functions and parameters of the model are fixed by previous calculations of N pi and N pi pi, etc., decays. Our results show that it should be possible to discover several new negative parity excited baryons and confirm the discovery of several others by analyzing these final states in kaon production experiments. We also establish clear predictions for the relative strengths of certain states to decay to Lambda(1405) K and Lambda(1520) K, which can be tested to determine if a three-quark model of the Lambda(1405) K is valid. Our results compare favorably with the results of partial wave analyses of the limited existing data for the Lambda K and Sigma K channels. We do not find large Sigma K decay amplitudes for a substantial group of predicted and weakly established negative-parity states, in contrast to the only previous work to consider decays of these states into the strange final states Lambda K and Sigma K.Comment: 25 pages, 8 figures, RevTe

    Time-division multiplexing for cable reduction in ultrasound imaging catheters

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    In ultrasound imaging catheter applications, gathering the data from multi-element transducer arrays is difficult as there is a restriction on cable count due to the diameter of the catheter. In such applications, CMUT-on-CMOS technology allows for 2D arrays with many elements to be designed and bonded directly onto CMOS circuitry. This allows for complex electronics to be placed at the tip of the catheter which leads to the possibility to include electronic multiplexing techniques to greatly reduce the cable count required for a large element array. Current approaches to cable reduction tend to rely on area and power hungry circuits to function, making them unsuitable for use in catheters. Furthermore the length requirement for catheters and lack of power available to on-chip cable drivers leads to limited signal strength at the receiver end. In this paper an alternative approach using Analogue Time Division Multiplexing (TDM) is presented, which addresses the cable restrictions of the catheter and, using a novel digital demultiplexing technique, allows for a reduction in the number of analogue signal processing stages required

    Annual direct and indirect costs attributable to nocturia in Germany, Sweden, and the UK

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    OBJECTIVE: Our aim was to estimate the prevalence-based cost of illness imposed by nocturia (≥2 nocturnal voids per night) in Germany, Sweden, and the UK in an average year. METHODS: Information obtained from a systematic review of published literature and clinicians was used to construct an algorithm depicting the management of nocturia in these three countries. This enabled an estimation of (1) annual levels of healthcare resource use, (2) annual cost of healthcare resource use, and (3) annual societal cost arising from presenteeism and absenteeism attributable to nocturia in each country. RESULTS: In an average year, there are an estimated 12.5, 1.2, and 8.6 million patients ≥20 years of age with nocturia in Germany, Sweden, and the UK, respectively. In an average year in each country, respectively, these patients were estimated to have 13.8, 1.4, and 10.0 million visits to a family practitioner or specialist, ~91,000, 9000, and 63,000 hospital admissions attributable to nocturia and 216,000, 19,000, and 130,000 subjects were estimated to incur a fracture resulting from nocturia. The annual direct cost of healthcare resource use attributable to managing nocturia was estimated to be approximately €2.32 billion in Germany, 5.11 billion kr (€0.54 billion) in Sweden, and £1.35 billion (€1.77 billion) in the UK. The annual indirect societal cost arising from both presenteeism and absenteeism was estimated to be approximately €20.76 billion in Germany and 19.65 billion kr (€2.10 billion) in Sweden. In addition, in the UK, the annual indirect cost due to absenteeism was an estimated £4.32 billion (€5.64 billion). CONCLUSIONS: Nocturia appears to impose a substantial socioeconomic burden in all three countries. Clinical and economic benefits could accrue from an increased awareness of the impact that nocturia imposes on patients, health services, and society as a whole
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