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The linewidth of the resonances in the single-electron tunneling spectra has been investigated for PbSe semiconductor nanocrystals (NCs) with scanning tunneling spectroscopy at low temperature. The linewidth of the resonances corresponding to tunneling through the first conduction and valence levels is found to increase with decreasing size of the NCs. Based on theoretical calculations, this broadening is mainly induced by the coupling between the tunneling electrons and the longitudinal optical phonon mode of the NC, and by the splitting of the degenerate electronic levels between the different L-valleys in the Brillouin zone. For the smallest sizes, it is shown that the intervalley splitting is the major source of broadening. [ABSTRACT FROM AUTHOR]

Purpose: The Core Outcome Measure Index (COMI) is a multidimensional questionnaire that investigates five dimensions in low back pain (LBP) patients, but does not address the psychological dimension. As the biopsychosocial perspective is recognized as important to capture the entire clinical picture of these patients, this multicenter prospective cohort study was designed to investigate the psychometric properties of a modified version of the COMI (COMIAD) which included 2 additional items, exploring anxiety and depression, respectively.Methods: 168 subacute or chronic LBP patients recruited in spine clinics completed a set of questionnaires before and after treatment (follow-up at 6 months). Construct validity was explored by comparing each item of the COMIAD to validated full-length questionnaires. Thus two additional questionnaires were included to assess the construct validity of the anxiety and depression measures. The psychometric properties of the COMI and COMIAD were then compared.Results: The two new items showed good internal consistency, high correlations with the corresponding full-length questionnaires, no floor or ceiling effect and good reproducibility (test-retest agreement kappa 0.68 for anxiety, 0.62 for depression). The addition of the 2 items did not alter internal validity (Cronbach's alpha = 0.88 and 0.87, respectively). The smallest detectable difference, the Minimal Clinically Important Improvement and the Patient Acceptable Symptom State were only minimally affected by the changes.Conclusion: The questions exploring anxiety and depression have good intrinsic and psychometric capacities (i.e., no floor or ceiling effects and high correlations with full-length scales) and did not significantly modify the psychometrics of the original COMI questionnaire. The COMIAD offers the possibility to include the psychological dimension in the multidimensional evaluation without significantly affecting questionnaire length. [ABSTRACT FROM AUTHOR]

Purpose: The Dallas Pain Questionnaire (DPQ) assesses the impact of low back pain (LBP) on four components (0-100) of daily life. We estimated the minimal clinically important improvement (MCII) and the patient acceptable symptom state (PASS) values of DPQ in LBP patients.Methods: 142 patients with LBP lasting for at least 4 weeks completed a battery of questionnaires at baseline and 6 months later. Questions for MCII addressed patient-reported response to treatment at 6 months on a five-point Likert scale, while a yes/no question concerning satisfaction with present state was used to determine PASS. MCII was computed as the difference in mean DPQ scores between patients reporting treatment as effective vs. patients reporting treatment as not effective, and PASS was computed as the third quartile of the DPQ score among patients who reported being satisfied with their present state.Results: MCII values were 22, 23, 2 and 10 for daily activities, work and leisure, social interest, and anxiety/depression, respectively. PASS values were 29, 23, 20 and 21 for the four components, respectively. The PASS total score threshold of 24 correctly classified 84.1 % of the patients who reported being unsatisfied with their present state, and 74.7 % of patients reported being satisfied.Conclusions: These values give information of paramount importance for clinicians in interpreting change in DPQ values over time. Authors should be encouraged to report the percentage of patients who reach MCII and PASS values in randomized clinical trials and cohort studies to help clinicians to interpret clinical results. [ABSTRACT FROM AUTHOR]

Purpose: A systematic search was conducted to study the efficiency of preventive educational interventions mainly focused on a biomechanical/biomedical model. Methods: The Pubmed electronic database and the Cochrane Library were searched based on a combination of keywords related to low back pain (LBP) and posture education. Only randomized controlled trial (RCT) studying the efficiency on outcomes directly related to LBP of a preventive intervention programme mainly based on education of proper care of the back for subjects not seeking treatment were included. References of the articles meeting these inclusion criteria were also checked to identify other potential citations. Besides, a methodological study assessment of the included RCTs was performed. Results: Nine studies, all conducted at the workplace were included in this review. Their mean quality level was low (5.1/12) and among the four studies with a huge sample size ( n > 400 subjects), only one had an acceptable methodological quality score (6/12). The education interventions differed widely from one study to another. No significant differences between the control and education groups were found at the follow-up in eight out of the nine studies on the incidence of back pain, disability and sick leave. Conclusions: The results of the RCTs included in this review suggest that educational interventions mainly focused on a biomechanical/biomedical model are not effective in preventing LBP. However, taking into account the methodological quality level of the RCTs as well as the very short and heterogeneous interventions often proposed, additional high-quality studies with a longer education period are needed to conclude that such interventions are inefficient. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the inter-session, inter-tester and inter-site reproducibility of trunk muscle strength scores in flexion, extension, lateral flexion and rotation. Ten healthy students were tested on four apparatus with a 7-10 day break between sessions. The first two sessions were identical while the other two differed either by the tester or by the site. Furthermore, 10 patients with chronic low back dysfunction (CLBD) were assessed with the four apparatus, once only. For all tests, CV ranged from 3.4% to 7.6% and from 3.9% to 8.1% in the inter-session and inter-tester studies, respectively (p>0.05 except for inter-session reproducibility of trunk flexor strength). Peak torque (PT) was more variable from site to site with a CV ranging from 4.2% to 12.7%, particularly in extension and left lateral flexion (p< 0.05). No statistically significant difference in the strength ratios (flexion/extension, right/left lateral-flexion and right/left rotation) were found between sessions or testers (4.9% < CV < 9.7%. The inter-site reproducibility of ratios was lower. Comparison between the CLBD patients and the healthy subjects with regard to PT normalized to body weight indicated significantly decreased performance for the former except for flexion and rotation scores in males. We conclude that in the case of healthy subjects, inter-session and inter-tester trunk strength measurements derived from these devices are reproducible. The low inter-site reproducibility suggests that caution should be exercised when interpreting findings originating from different sites. The lower extension strength scores in CLBD patients test lends some validity to the system. However, further studies focusing on reproducibility and validity of this system in CLBD patients are critical before any conclusion regarding their clinical viability may be drawn. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the inter-session, inter-tester and inter-site reproducibility of trunk muscle strength scores in flexion, extension, lateral flexion and rotation. Ten healthy students were tested on four apparatus with a 7–10 day break between sessions. The first two sessions were identical while the other two differed either by the tester or by the site. Furthermore, 10 patients with chronic low back dysfunction (CLBD) were assessed with the four apparatus, once only. For all tests, CV ranged from 3.4% to 7.6% and from 3.9% to 8.1% in the inter-session and inter-tester studies, respectively (p>0.05 except for inter-session reproducibility of trunk flexor strength). Peak torque (PT) was more variable from site to site with a CV ranging from 4.2% to 12.7%, particularly in extension and left lateral flexion (p< 0.05). No statistically significant difference in the strength ratios (flexion/extension, right/left lateral-flexion and right/left rotation) were found between sessions or testers (4.9% < CV < 9.7%. The inter-site reproducibility of ratios was lower. Comparison between the CLBD patients and the healthy subjects with regard to PT normalized to body weight indicated significantly decreased performance for the former except for flexion and rotation scores in males. We conclude that in the case of healthy subjects, inter-session and inter-tester trunk strength measurements derived from these devices are reproducible. The low inter-site reproducibility suggests that caution should be exercised when interpreting findings originating from different sites. The lower extension strength scores in CLBD patients test lends some validity to the system. However, further studies focusing on reproducibility and validity of this system in CLBD patients are critical before any conclusion regarding their clinical viability may be drawn. [ABSTRACT FROM AUTHOR]

Ga[sub 1-x]Mn[sub x]As layers with Mn composition of up to 6.2% are investigated by cross-sectional scanning tunneling microscopy and spectroscopy. We identify in the tunneling spectra contributions from Mn[sup -, sub Ga] acceptor states, compensating As[sup 2+, sub Ga] donor states, and additional compensating donor states, which we suggest to be Mn[sup 2+, sub i] interstitials. On basis of the observed Fermi level shift and a charge carrier compensation analysis, we deduce the concentration of Mn[sup 2+, sub i] interstitials. Furthermore, scanning tunneling microscopy images suggest an inhomogeneous distribution of Mn dopant atoms. [ABSTRACT FROM AUTHOR]