324 research outputs found

    Wavelength dependent ac-Stark shift of the 1S0 - 3P1 transition at 657 nm in Ca

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    We have measured the ac-Stark shift of the 4s2 1S0 - 4s4p 3P1 line in 40Ca for perturbing laser wavelengths between 780 nm and 1064 nm with a time domain Ramsey-Borde atom interferometer. We found a zero crossing of the shift for the mS = 0 - mP = 0 transition and \sigma polarized perturbation at 800.8(22) nm. The data was analyzed by a model deriving the energy shift from known transition wavelengths and strengths. To fit our data, we adjusted the Einstein A coefficients of the 4s3d 3D - 4s4p 3P and 4s5s 3S - 4s4p 3P fine structure multiplets. With these we can predict vanishing ac-Stark shifts for the 1S0 m = 0 - 3P1 m = 1 transition and \sigma- light at 983(12) nm and at 735.5(20) nm for the transition to the 3P0 level.Comment: 8 pages, 5 figures, 2 table

    Low grade chondrosarcoma : is long-term follow-up necessary?

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    INTRODUCTION: Currently, the follow-up regimen for patients treated for low-grade chondrosarcoma is similar to that of all chondrosarcomas. It is possible that low-grade chondrosarcoma may have a far more benign course than other chondrosarcomas and, if treated adequately, may require a far less vigorous follow-up regimen. PATIENTS AND METHODS: A retrospective study was performed on all patients treated for chondrosarcoma at the Pretoria Musculoskeletal Tumour Unit,, University of Pretoria, over a 22-year period, between 1987 and 2009. In total 56 patients were treated for chondrosarcoma over this period, but two patients were lost to follow-up. The study totalled 54 patients. The grade of chondrosarcoma, outcome and tumour recurrence was evaluated in these patients. The lesions were divided into four histological grades: atypical enchondroma (grade 0), low-grade chondrosarcoma (grade I), intermediate grade chondrosarcoma (grade II), and high-grade chondrosarcoma (grade III). RESULTS: Histologically 46 tumours were low-grade (grade 0 or I) chondrosarcoma (82%), there were nine cases of intermediate (grade II) chondrosarcoma (16%), and one patient had a metastatic mesenchymal chondrosarcoma. The femur and humerus were the commonest sites involved. The axial skeleton was affected in only three cases, all of which had more aggressive lesions. Two patients died, one with metastatic mesenchymal chondrosarcoma involving the scapula, and the other with an intermediate (grade 2) lesion of the pelvis. There was no tumour recurrence in 49 patients after a mean period of 57.5 months, of which 42 patients had low-grade (grade 1) lesions, and seven patients had intermediate (grade 2) lesions. Two patients with low-grade lesions were lost to follow-up. Three patients presented with recurrence, all of which had a local recurrence. No metastatic disease was detected radiographically. Of these three patients one had a grade 2 lesion, and the other two patients were initially not treated with surgical adjuvant therapy. Not one patient with low-grade chondrosarcoma treated adequately with local curettage and surgical adjuvant therapy presented with local recurrence or distal metastasis.CONCLUSION: We believe that adequately treated low-grade chondrosarcomas have a very low local recurrence rate. Treatment consists of local curettage with surgical adjuvant therapy. When faced with recurrence, it rarely presents with distant metastases. A revised follow-up schedule is advised consisting of visits at 3 and 6 months and followed by yearly visits for 5 years. This appears to be adequate for timely detection and treatment of any local recurrence of low-grade chondrosarcoma.http://www.charpublications.co.za/C_JournalsORTH.as

    Influence of large local and non-local bispectra on primordial black hole abundance

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    Primordial black holes represent a unique probe to constrain the early universe on small scales - providing the only constraints on the primordial power spectrum on the majority of scales. However, these constraints are strongly dependent on even small amounts of non-Gaussianity, which is unconstrained on scales significantly smaller than those visible in the CMB. This paper goes beyond previous considerations to consider the effects of a bispectrum of the equilateral, orthogonal and local shapes with arbitrary magnitude upon the abundance of primordial black holes. Non-Gaussian density maps of the early universe are generated from a given bispectrum and used to place constraints on the small scale power spectrum. When small, we show that the skewness provides an accurate estimate for how the constraint depends on non-Gaussianity, independently of the shape of the bispectrum. We show that the orthogonal template of non-Gaussianity has an order of magnitude weaker effect on the constraints than the local and equilateral templates.Comment: 11 pages, 4 figures, updated to match published version in JCAP02(2016)029, Journal of Cosmology and Astroparticle Physics, Volume 2016, February 201

    High quality of SARS-CoV-2 molecular diagnostics in a diverse laboratory landscape through supported benchmark testing and External Quality Assessment

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    A two-step strategy combining assisted benchmark testing (entry controls) and External Quality Assessments (EQAs) with blinded simulated clinical specimens to enhance and maintain the quality of nucleic acid amplification testing was developed. This strategy was successfully applied to 71 diagnostic laboratories in The Netherlands when upscaling the national diagnostic capacity during the SARS-CoV-2 pandemic. The availability of benchmark testing in combination with advice for improvement substantially enhanced the quality of the laboratory testing procedures for SARS-CoV-2 detection. The three subsequent EQA rounds demonstrated high quality testing with regard to specificity (99.6% correctly identified) and sensitivity (93.3% correctly identified). Even with the implementation of novel assays, changing workflows using diverse equipment and a high degree of assay heterogeneity, the overall high quality was maintained using this two-step strategy. We show that in contrast to the limited value of Cq value for absolute proxies of viral load, these Cq values can, in combination with metadata on strategies and techniques, provide valuable information for laboratories to improve their procedures. In conclusion, our two-step strategy (preparation phase followed by a series of EQAs) is a rapid and flexible system capable of scaling, improving, and maintaining high quality diagnostics even in a rapidly evolving (e.g. pandemic) situation.</p

    High quality of SARS-CoV-2 molecular diagnostics in a diverse laboratory landscape through supported benchmark testing and External Quality Assessment

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    A two-step strategy combining assisted benchmark testing (entry controls) and External Quality Assessments (EQAs) with blinded simulated clinical specimens to enhance and maintain the quality of nucleic acid amplification testing was developed. This strategy was successfully applied to 71 diagnostic laboratories in The Netherlands when upscaling the national diagnostic capacity during the SARS-CoV-2 pandemic. The availability of benchmark testing in combination with advice for improvement substantially enhanced the quality of the laboratory testing procedures for SARS-CoV-2 detection. The three subsequent EQA rounds demonstrated high quality testing with regard to specificity (99.6% correctly identified) and sensitivity (93.3% correctly identified). Even with the implementation of novel assays, changing workflows using diverse equipment and a high degree of assay heterogeneity, the overall high quality was maintained using this two-step strategy. We show that in contrast to the limited value of Cq value for absolute proxies of viral load, these Cq values can, in combination with metadata on strategies and techniques, provide valuable information for laboratories to improve their procedures. In conclusion, our two-step strategy (preparation phase followed by a series of EQAs) is a rapid and flexible system capable of scaling, improving, and maintaining high quality diagnostics even in a rapidly evolving (e.g. pandemic) situation.</p

    “Spontaneous” late recovery from stuttering: Dimensions of reported techniques and causal attributions

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    Purpose: (1) To survey the employed techniques and the reasons/occasions which adults who had recovered from stuttering after age 11 without previous treatment reported as causal to overcome stuttering, (2) to investigate whether the techniques and causal attributions can be reduced to coherent (inherently consistent) dimensions, and (3) whether these dimensions reflect common therapy components. Methods: 124 recovered persons from 8 countries responded by SurveyMonkey or paper-and-pencil to rating scale questions about 49 possible techniques and 15 causal attributions. Results: A Principal Component Analysis of 110 questionnaires identified 6 components (dimensions) for self-assisted techniques (Speech Restructuring; Relaxed/Monitored Speech; Elocution; Stage Performance; Sought Speech Demands; Reassurance; 63.7% variance explained), and 3 components of perceived causal attributions of recovery (Life Change, Attitude Change, Social Support; 58.0% variance explained). Discussion: Two components for self-assisted techniques (Speech Restructuring; Elocution) reflect treatment methods. Another component (Relaxed/Monitored Speech) consists mainly of items that reflect a common, non-professional understanding of effective management of stuttering. The components of the various perceived reasons for recovery reflect differing implicit theories of causes for recovery from stuttering. These theories are considered susceptible to various biases. This identification of components of reported techniques and of causal attributions is novel compared to previous studies who just list techniques and attributions. Conclusion: The identified dimensions of self-assisted techniques and causal attributions to reduce stuttering as extracted from self-reports of a large, international sample of recovered formerly stuttering adults may guide the application of behavioral stuttering therapies

    ARIA 2016: Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

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    The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma a

    Search for electroweak production of single top quarks in ppˉp\bar{p} collisions.

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    We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb. (arXiv
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