399 research outputs found

    Confining potential in momentum space

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    A method is presented for the solution in momentum space of the bound state problem with a linear potential in r space. The potential is unbounded at large r leading to a singularity at small q. The singularity is integrable, when regulated by exponentially screening the r-space potential, and is removed by a subtraction technique. The limit of zero screening is taken analytically, and the numerical solution of the subtracted integral equation gives eigenvalues and wave functions in good agreement with position space calculations

    Solution of two-body relativistic bound state equations with confining plus Coulomb interactions

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    Studies of meson spectroscopy have often employed a nonrelativistic Coulomb plus Linear Confining potential in position space. However, because the quarks in mesons move at an appreciable fraction of the speed of light, it is necessary to use a relativistic treatment of the bound state problem. Such a treatment is most easily carried out in momentum space. However, the position space Linear and Coulomb potentials lead to singular kernels in momentum space. Using a subtraction procedure we show how to remove these singularities exactly and thereby solve the Schroedinger equation in momentum space for all partial waves. Furthermore, we generalize the Linear and Coulomb potentials to relativistic kernels in four dimensional momentum space. Again we use a subtraction procedure to remove the relativistic singularities exactly for all partial waves. This enables us to solve three dimensional reductions of the Bethe-Salpeter equation. We solve six such equations for Coulomb plus Confining interactions for all partial waves

    Hyperonic mixing in five-baryon double-strangeness hypernuclei in a two-channel treatment

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    Properties of hypernuclei ΛΛ5_{\Lambda \Lambda}^5H and ΛΛ5_{\Lambda \Lambda }^5He are studied in a two-channel approach with explicit treatment of coupling of channels ^3\text{Z}+\Lambda+\Lambda and \alpha+\Xi. Diagonal \Lambda\Lambda and coupling \Lambda\Lambda-\Xi N interactions are derived within G-matrix procedure from Nijmegen meson-exchange models. Bond energy \Delta B_{\Lambda\Lambda} in ΛΛ5_{\Lambda \Lambda}^5He exceeds significantly that in ΛΛ5_{\Lambda \Lambda}^5H due to the channel coupling. Diagonal \Xi\alpha attraction amplifies the effect, which is sensitive also to \Lambda-core interaction. The difference of the \Delta B_{\Lambda\Lambda} values can be an unambiguous signature of the \Lambda\Lambda-\Xi N coupling in \Lambda\Lambda hypernuclei. However, improved knowledge of the hyperon-nucleus potentials is needed for quantitative extraction of the coupling strength from future data on the \Lambda\Lambda hypernuclear binding energies.Comment: 11 pages with 3 figures; Phys. Rev. C, accepte

    Temocillin in the treatment of Burkholderia cepacia infection in cystic fibrosis

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    AbstractBackgroundInfections due to Burkholderia cepacia complex (Bcc) strains increase morbidity and mortality in cystic fibrosis (CF). Some transplant centres reject Bcc infected patients. We reviewed the results in patients treated with i.v temocillin.MethodsTwenty-three patients who received 38 courses of temocillin (1988–1998) were identified from the CF database at Royal Brompton Hospital. In three patients' data were inadequate; therefore analysis was done in 20. Outcome was measured as improvement, deterioration or no change (compared to admission) in the following categories: clinical (temperature, dyspnoea, sputum volume, chest pain), physiological (FEV1, FVC, oxygen saturation) and inflammatory markers (WBC, ESR, CRP). Patients who improved in two categories were classified as having improved. Antibiotic sensitivities and outcome were recorded.ResultsIn 18 of 32 courses (56.25%) improvement occurred. The organism (Bcc) in eight patients' sputum became resistant (three died). The antibiotics was changed in five patients with Bcc strains sensitive to temocillin because of no improvement and one patient due to allergy (rash). The average time to the next i.v antibiotic was 41 days. Eight patients died (in three the Bcc strain was resistant to temocillin). Fourteen patients with Bcc were transplanted and eight patients survived. Another patient who developed Bcc infection post-operatively, failing to respond to temocillin.ConclusionsThese results suggest the potential benefit of i.v temocillin in CF patients with Bcc for exacerbations and at the time of transplantation

    Stochastic Variational Search for ΛΛ4^{4}_{\Lambda\Lambda}H

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    A four-body calculation of the pnΛΛpn\Lambda\Lambda bound state, $^{\ 4}_{\Lambda\Lambda}H,isperformedusingthestochasticvariationalmethodandphenomenologicalpotentials.TheH, is performed using the stochastic variational method and phenomenological potentials. The NN,, \Lambda N,and, and \Lambda\LambdapotentialsaretakenfromarecentLetterbyFilikhinandGal,PRL89,172502(2002).AlthoughtheirFaddeevYakubovskycalculationfoundnoboundstatesolutionoverawiderangeof potentials are taken from a recent Letter by Filikhin and Gal, PRL{\bf 89}, 172502 (2002). Although their Faddeev-Yakubovsky calculation found no bound-state solution over a wide range of \Lambda\Lambdainteractionstrengths,thepresentvariationalcalculationgivesaboundstateenergy,whichisclearlylowerthanthe interaction strengths, the present variational calculation gives a bound-state energy, which is clearly lower than the _\Lambda^3{H}+\Lambdathreshold,evenforaweak threshold, even for a weak \Lambda\Lambdainteractionstrengthdeducedfromarecentexperimental interaction strength deduced from a recent experimental B_{\Lambda\Lambda}(^{6}_{\Lambda\Lambda}{He})value.Thebindingenergiesobtainedarecloseto,andslightlylargerthan,thevaluesobtainedfromthethreebody value. The binding energies obtained are close to, and slightly larger than, the values obtained from the three-body d\Lambda\Lambda$ model in the Letter.Comment: Corrected typos, added addtional calculations regarding a truncated to l=0 interaction model, 4 pages, 3 figure

    Control Management and Business Performances: the Malaysian Family SMEs Perspectives

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    This study examined the relationship between control management and family business performance in the Malaysian context. It has two objectives, the first being to determine the relationship of organizational credit control policy and procedures, employee development and motivation, and intelligence collection systems to subsequent collection reports in Malaysian family SMEs. The second objective is to investigate the moderating effect of participation in decision-making and work effort towards innovation and business performance. This is a descriptive study involving 90 senior executives employed in 90 Malaysian family SMEs/firms. A correlation analysis from this study confirmed previous researchers’ observations that high-level organizational commitment to credit control management is linked to improvements in business performance. The results suggest that three components – credit policy, employee development, and intelligence collection systems – are the most important predictors for the efficiency and effectiveness of credit control management.   &nbsp

    A woman with cystic fibrosis, severe hypoxaemia, an atrial thrombus and a patent foramen ovale: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Cystic fibrosis is usually associated with chronic pulmonary sepsis and frequent infective exacerbations. We report a very unusual cause of severe hypoxaemia in a woman with cystic fibrosis caused by thrombus formation in the right atrium.</p> <p>Case presentation</p> <p>A 21-year-old Caucasian woman with cystic fibrosis and a totally implantable venous access device presented with severe hypoxaemia. This was initially treated with antibiotics but her oxygen levels did not improve significantly. Subsequently, a transient ischaemic attack occurred. Further investigations, including a contrast echocardiogram and a cardiac magnetic resonance scan, revealed the presence of a large right atrial thrombus and right-to-left intracardiac shunt through a patent foramen ovale.</p> <p>Conclusion</p> <p>This case highlights the need to consider a right-to-left shunt in chronic respiratory diseases when hypoxaemia is out of proportion to the degree of lung function impairment. Totally implantable venous access devices should always be considered as a source of thrombus formation.</p

    Osteopontin as potential biomarker and therapeutic target in gastric and liver cancers

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