Chiral dynamics in form factors, spectral-function sum rules, meson-meson scattering and semilocal duality

In this work, we perform the one-loop calculation of the scalar and pseudoscalar form factors in the framework of U(3) chiral perturbation theory with explicit tree level exchanges of resonances. The meson-meson scattering calculation from Ref.[1] is extended as well. The spectral functions of the nonet scalar-scalar (SS) and pseudoscalar-pseudoscalar (PP) correlators are constructed by using the corresponding form factors. After fitting the unknown parameters to the scattering data, we discuss the resonance content of the resulting scattering amplitudes. We also study spectral-function sum rules in the SS-SS, PP-PP and SS-PP sectors as well as semi-local duality from scattering. The former relate the scalar and pseudoscalar spectra between themselves while the latter mainly connects the scalar spectrum with the vector one. Finally we investigate these items as a function of Nc for Nc > 3. All these results pose strong constraints on the scalar dynamics and spectroscopy that are discussed. They are successfully fulfilled by our meson-meson scattering amplitudes and spectral functions.Comment: 45 pages, 17 figures and 4 tables. To match the published version in PRD: a new paragraph is added in the Introduction and two new references are include

Resonances from meson-meson scattering in U(3) CHPT

In this work, the complete one loop calculation of meson-meson scattering amplitudes within U(3)\otimes U(3) chiral perturbation theory with explicit resonance states is carried out for the first time. Partial waves are unitarized from the perturbative calculation employing a non-perturbative approach based on the N/D method. Once experimental data are reproduced in a satisfactory way we then study the resonance properties, such as the pole positions, corresponding residues and their N_C behaviors. The resulting N_C dependence is the first one in the literature that takes into account the fact that the \eta_1 becomes the ninth Goldstone boson in the chiral limit for large N_C. Within this scheme the vector resonances studied, \rho(770), K^*(892) and \phi(1020), follow an N_C trajectory in agreement with their standard \bar{q}q interpretation. The scalars f_0(1370), a_0(1450) and K^*(1430) also have for large N_C a \bar{q}q pole position trajectory and all of them tend to a bare octet of scalar resonances around 1.4 GeV. The f_0(980) tends asymptotically to the bare pole position of a singlet scalar resonance around 1 GeV. The \sigma, \kappa and a_0(980) scalar resonances have a very different N_C behavior. The case of the \sigma resonance is analyzed with special detail.Comment: 50 pages, 15 figures, 1 table. Enlarged version with more detail comparisons with previous results in the literature. To match with accepted version for publicatio

A low-lying scalar meson nonet in a unitarized meson model

A unitarized nonrelativistic meson model which is successful for the description of the heavy and light vector and pseudoscalar mesons yields, in its extension to the scalar mesons but for the same model parameters, a complete nonet below 1 GeV. In the unitarization scheme, real and virtual meson-meson decay channels are coupled to the quark-antiquark confinement channels. The flavor-dependent harmonic-oscillator confining potential itself has bound states epsilon(1.3 GeV), S(1.5 GeV), delta(1.3 GeV), kappa(1.4 GeV), similar to the results of other bound-state qqbar models. However, the full coupled-channel equations show poles at epsilon(0.5 GeV), S(0.99 GeV), delta(0.97 GeV), kappa(0.73 GeV). Not only can these pole positions be calculated in our model, but also cross sections and phase shifts in the meson-scattering channels, which are in reasonable agreement with the available data for pion-pion, eta-pion and Kaon-pion in S-wave scattering.Comment: A slightly revised version of Zeitschrift fuer Physik C30, 615 (1986

S-wave Meson-Meson Scattering from Unitarized U(3) Chiral Lagrangians

An investigation of the s-wave channels in meson-meson scattering is performed within a U(3) chiral unitary approach. Our calculations are based on a chiral effective Lagrangian which includes the eta' as an explicit degree of freedom and incorporates important features of the underlying QCD Lagrangian such as the axial U(1) anomaly. We employ a coupled channel Bethe-Salpeter equation to generate poles from composed states of two pseudoscalar mesons. Our results are compared with experimental phase shifts up to 1.5 GeV and effects of the eta' within this scheme are discussed.Comment: 18 pages, 6 figure

Advancing the argument for validity of the Alberta Context Tool with healthcare aides in residential long-term care

<p>Abstract</p> <p>Background</p> <p>Organizational context has the potential to influence the use of new knowledge. However, despite advances in understanding the theoretical base of organizational context, its measurement has not been adequately addressed, limiting our ability to quantify and assess context in healthcare settings and thus, advance development of contextual interventions to improve patient care. We developed the Alberta Context Tool (the ACT) to address this concern. It consists of 58 items representing 10 modifiable contextual concepts. We reported the initial validation of the ACT in 2009. This paper presents the second stage of the psychometric validation of the ACT.</p> <p>Methods</p> <p>We used the <it>Standards for Educational and Psychological Testing </it>to frame our validity assessment. Data from 645 English speaking healthcare aides from 25 urban residential long-term care facilities (nursing homes) in the three Canadian Prairie Provinces were used for this stage of validation. In this stage we focused on: (1) advanced aspects of internal structure (e.g., confirmatory factor analysis) and (2) relations with other variables validity evidence. To assess reliability and validity of scores obtained using the ACT we conducted: Cronbach's alpha, confirmatory factor analysis, analysis of variance, and tests of association. We also assessed the performance of the ACT when individual responses were aggregated to the care unit level, because the instrument was developed to obtain unit-level scores of context.</p> <p>Results</p> <p>Item-total correlations exceeded acceptable standards (> 0.3) for the majority of items (51 of 58). We ran three confirmatory factor models. Model 1 (all ACT items) displayed unacceptable fit overall and for five specific items (1 item on <it>adequate space for resident care </it>in the Organizational Slack-Space ACT concept and 4 items on use of electronic resources in the Structural and Electronic Resources ACT concept). This prompted specification of two additional models. Model 2 used the 7 scaled ACT concepts while Model 3 used the 3 count-based ACT concepts. Both models displayed substantially improved fit in comparison to Model 1. Cronbach's alpha for the 10 ACT concepts ranged from 0.37 to 0.92 with 2 concepts performing below the commonly accepted standard of 0.70. Bivariate associations between the ACT concepts and instrumental research utilization levels (which the ACT should predict) were statistically significant at the 5% level for 8 of the 10 ACT concepts. The majority (8/10) of the ACT concepts also showed a statistically significant trend of increasing mean scores when arrayed across the lowest to the highest levels of instrumental research use.</p> <p>Conclusions</p> <p>The validation process in this study demonstrated additional empirical support for construct validity of the ACT, when completed by healthcare aides in nursing homes. The overall pattern of the data was consistent with the structure hypothesized in the development of the ACT and supports the ACT as an appropriate measure for assessing organizational context in nursing homes. Caution should be applied in using the one space and four electronic resource items that displayed misfit in this study with healthcare aides until further assessments are made.</p

Using Voice Recognition Software to improve communicative writing and social participation in an individual with severe acquired dysgraphia: an experimental single case therapy study

Background Two previous single-case studies have reported that voice recognition software (VRS) can be a powerful tool for circumventing impaired writing in aphasia (Bruce et al, 2003; Estes & Bloom, 2011). However, these studies report mixed results regarding transfer of skills to functional tasks, such as emailing. Method A single-case therapy study was conducted with “Stephen”, a 63 -year old man with fluent aphasia and severe acquired dysgraphia and dyslexia limiting his social participation and ability to return to work. Treatment consisted of 16 one-hour sessions. Stephen was trained to use Dragon NaturallySpeakingRTM VRS to assist writing and Read+WriteGoldRTM text-to-speech software to assist reading, and to develop computer skills required to use email. Outcome measures evaluated writing efficiency and communicative effectiveness, the functional impact of the intervention, and changes in participation. Results Training produced significant gains in the efficiency and communicative effectiveness of Stephen’s writing, despite his underlying writing impairment remaining unchanged. Gains generalised to everyday functional communication, leading to increased social participation with Stephen undertaking a wider range of social activities and increasing his social network following treatment. Gains were maintained at follow-up assessment. Discussion Results indicate that a relatively short training period with assistive technologies achieved extensive generalisation to independent, functional communicative writing. Indeed, for this case, VRS training may have exceeded the degree of improvement in functional text writing that could have been achieved through impairment therapy, since gains were not limited to treated vocabulary. Some challenges were encountered in training Stephen to use VRS but, through adaptations to the training process, were largely overcome. Importantly, regaining independent writing skills resulted in profound and life-changing improvements to social participation. This may have resulted in Stephen reconnecting with important aspects of his pre-stroke identity, and improving his self-esteem. Conclusion This case adds to a small evidence base indicating that training in the use of VRS, in combination with text-to-speech software, may be an effective way to address writing impairments in chronic aphasia for individuals with relatively well-preserved spoken output. Not only can these technologies improve the efficiency and communicative effectiveness of writing, they can also lead to significant gains in functional communication and social participation. Further research is needed trialing this approach with a larger group of people with aphasia

Self-Efficacy, Problem Solving, and Social-Environmental Support Are Associated With Diabetes Self-Management Behaviors

OBJECTIVE — To evaluate associations between psychosocial and social-environmental variables and diabetes self-management, and diabetes control. RESEARCH DESIGN AND METHODS — Baseline data from a type 2 diabetes self-management randomized trial with 463 adults having elevated BMI (M 34.8 kg/m2) were used to investigate relations among demographic, psychosocial, and social-environmental variables; dietary, exercise, and medication-taking behaviors; and biologic outcomes. RESULTS — Self-efficacy, problem solving, and social-environmental support were indepen-dently associated with diet and exercise, increasing the variance accounted for by 23 and 19%, respectively. Only diet contributed to explained variance in BMI ( 0.17, P 0.0003) and self-rated health status ( 0.25, P 0.0001); and only medication-taking behaviors contrib-uted to lipid ratio (total–to–HDL) (0.20, P 0.0001) and A1C (0.21, P 0.0001). CONCLUSIONS — Interventions should focus on enhancing self-efficacy, problem solving, and social-environmental support to improve self-management of diabetes. Diabetes Care 33:751–753, 2010 D iabetes management requires coor-dination between the patient andthe primary care team. Given the lifestyle changes required for self-management success, patient, social, and environmental factors, including health care (1) and community support (2), are increasingly recognized as important. Un-derstanding relations among demo-graphic, psychosocial, and social-environmental variables, and multiple health risk behaviors is critical to devel-oping interventions that will sustain health behavior changes. RESEARCH DESIGN AND METHODS — Baseline data were col-lected as part of a patient randomized trial to evaluate the impact of an interactive, multimedia diabetes self-management program relative to “enhanced ” usual car

Final State Interactions in Hadronic D decays

We show that the large corrections due to final state interactions (FSI) in the D^+\to \pi^-\pi^+\pi^+, D^+_s\to \pi^-\pi^+\pi^+, and D^+\to K^-\pi^+\pi^+ decays can be accounted for by invoking scattering amplitudes in agreement with those derived from phase shifts studies. In this way, broad/overlapping resonances in S-waves are properly treated and the phase motions of the transition amplitudes are driven by the corresponding scattering matrix elements determined in many other experiments. This is an important step forward in resolving the puzzle of the FSI in these decays. We also discuss why the \sigma and \kappa resonances, hardly visible in scattering experiments, are much more prominent and clearly visible in these decays without destroying the agreement with the experimental \pi\pi and K\pi low energy S-wave phase shifts.Comment: 22 pages, 6 figures, 5 tables. Minor changes. We extend the discusion when quoting a reference and we include a new one. Some typos are fixe

Pion Interactions in Chiral Field Theories

We study in various chiral models the pion charge radius, $\pi_{e3}$ form factor ratio, $\pi^\circ \to \gamma \gamma$ amplitude, charge pion polarizabilities, $\gamma\gamma \to \pi^\circ \pi^\circ$ amplitude at low energies and the $\pi\pi$ s-wave I = 0 scattering length. We find that a quark-level linear sigma-model approach (also being consistent with tree-level vector meson dominance) is quite compatible with all of the above data.Comment: 12 pages, 9 eps figure