Superallowed 0+ to 0+ nuclear beta decays: A new survey with precision tests of the conserved vector current hypothesis and the standard model

A new critical survey is presented of all half-life, decay-energy and branching-ratio measurements related to 20 0+ to 0+ beta decays. Compared with our last review, there are numerous improvements: First, we have added 27 recently published measurements and eliminated 9 references; of particular importance, the new data include a number of high-precision Penning-trap measurements of decay energies. Second, we have used the recently improved isospin symmetry-breaking corrections. Third, our calculation of the statistical rate function now accounts for possible excitation in the daughter atom. Finally, we have re-examined the systematic uncertainty associated with the isospin symmetry-breaking corrections by evaluating the radial-overlap correction using Hartree-Fock radial wave functions and comparing the results with our earlier calculations, which used Saxon-Woods wave functions; the provision for systematic uncertainty has been changed as a consequence. The new corrected Ft values are impressively constant and their average, when combined with the muon liftime, yields the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, V_{ud} = 0.97425(22). The unitarity test on the top row of the matrix becomes |V_{ud}|^2 + |V_{us}|^2 + |V_{ub}|^2 = 0.99995(61). Both V_{ud} and the unitarity sum have significantly reduced uncertainties compared with our previous survey, although the new value of V_{ud} is statistically consistent with the old one. From these data we also set limits on the possible existence of scalar interactions, right-hand currents and extra Z bosons. Finally, we discuss the priorities for future theoretical and experimental work with the goal of making the CKM unitarity test even more definitive.Comment: 36 pages, 11 tables, 9 figure

High Precision Measurement of the Superallowed 0^+ to 0^+ Beta Decay of ^{22}Mg

The half-life, 3.8755(12) s, and superallowed branching ratio, 0.5315(12), for ^{22}Mg beta-decay have been measured with high precision. The latter depended on gamma-ray intensities being measured with an HPGe detector calibrated for relative efficiencies to an unprecedented 0.15%. Previous precise measurements of 0^+ to 0^+ transitions have been restricted to the nine that populate stable daughter nuclei. No more such cases exist, and any improvement in a critical CKM unitarity test must depend on precise measurements of more exotic nuclei. With this branching-ratio measurement, we show those to be possible for T_z = -1 parents. We obtain a corrected Ft-value of 3071(9) s, in good agreement with expectations.Comment: 4 pages, 2 figures, revtex

Superallowed nuclear beta decays: A critical survey with tests of CVC and the standard model

A complete and critical survey is presented of all half-life, decay-energy and branching-ratio measurements related to 20 superallowed decays; no measurements are ignored, though some are rejected for cause and others updated. A new calculation of the statistical rate function is described and experimental ft values determined. The associated theoretical corrections needed to convert these results into Ft values are discussed, and careful attention is paid to the origin and magnitude of their uncertainties. As an exacting confirmation of the conserved vector current hypothesis, the Ft values are seen to be constant to 3 parts in 10^4. These data are also used to set new limits on any possible scalar interactions or right-hand currents. The average Ft value obtained from the survey, when combined with the muon lifetime, yields the CKM matrix element Vud = 0.9738(4); and the unitarity test on the top row of the matrix becomes |Vud|^2 + |Vus|^2 + |Vub|^2 = 0.9966(14) using the PDG's currently recommended values for Vus and Vub. We discuss the priorities for future theoretical and experimental work with the goal of making the CKM unitarity test more definitive.Comment: 64 pages, 4 postscript figure

Native Variants of the MRB1 Complex Exhibit Specialized Functions in Kinetoplastid RNA Editing

We want to thank Kathy Kyler for editing this manuscript, Ken Stuart for supplying monoclonal antisera against RECC subunits, and Laurie K. Read for her gift of polyclonal antisera against GAP1 and RGG2. Funding: National Science Foundation Grant No. NSF1122109 (PI: J.Cruz-Reyes.). NIH/National Institute of Allergies and Infectious Diseases R01 AI088011 (PI: Blaine Mooers). Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under grant number P20 GM103640. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Adaptation and survival of Trypanosoma brucei requires editing of mitochondrial mRNA by uridylate (U) insertion and deletion. Hundreds of small guide RNAs (gRNAs) direct the mRNA editing at over 3,000 sites. RNA editing is controlled during the life cycle but the regulation of substrate and stage specificity remains unknown. Editing progresses in the 3’ to 5’ direction along the pre-mRNA in blocks, each targeted by a unique gRNA. A critical editing factor is the mitochondrial RNA binding complex 1 (MRB1) that binds gRNA and transiently interacts with the catalytic RNA editing core complex (RECC). MRB1 is a large and dynamic complex that appears to be comprised of distinct but related subcomplexes (termed here MRBs). MRBs seem to share a ‘core’ complex of proteins but differ in the composition of the ‘variable’ proteins. Since some proteins associate transiently the MRBs remain imprecisely defined. MRB1 controls editing by unknown mechanisms, and the functional relevance of the different MRBs is unclear. We previously identified two distinct MRBs, and showed that they carry mRNAs that undergo editing. We proposed that editing takes place in the MRBs because MRBs stably associate with mRNA and gRNA but only transiently interact with RECC, which is RNA free. Here, we identify the first specialized functions in MRBs: 1) 3010-MRB is a major scaffold for RNA editing, and 2) REH2-MRB contains a critical trans-acting RNA helicase (REH2) that affects multiple steps of editing function in 3010-MRB. These trans effects of the REH2 include loading of unedited mRNA and editing in the first block and in subsequent blocks as editing progresses. REH2 binds its own MRB via RNA, and conserved domains in REH2 were critical for REH2 to associate with the RNA and protein components of its MRB. Importantly, REH2 associates with a ~30 kDa RNA-binding protein in a novel ~15S subcomplex in RNA-depleted mitochondria. We use these new results to update our model of MRB function and organization.Yeshttp://www.plosone.org/static/editorial#pee

Measuring Clients’ Perception of Functional Limitations Using the Perceived Functioning & Health Questionnaire

Background The Perceived Functioning & Health (PFH) questionnaire was developed to collect, in a standardized manner, which work activities are limited due to health conditions according to the perception of the client. In this study the questionnaire’s reliability and validity are investigated. Methods The PFH questionnaire is comprised of 147 questions, distributed over 33 scales, pertaining to the client’s psychosocial and physical work limitations. The PFH data of 800 respondents were analyzed: 254 healthy employees, 408 workers on sick leave and 138 recipients of a disability pension. Internal consistency (Cronbach’s α) for the scales was established. The test–retest reliability was examined for the data of 52 recipients of a disability pension who filled out the PFH twice within an interval of 1 month. Validation was established by taking the nature of the limitations as a criterion: mental limitations, physical limitations or a mix of both. To this end, the respondents were divided into groups distinguished on the basis of self-classification, as well as classification on the basis of disease codes given by insurance and occupational health physicians: a “healthy” group, subjects with only physical (“physical” group) or mental limitations (“mental” group) or mixed limitations (“mixed” group). The scale scores of these groups were compared and tested using analyses-of-variance and discriminant analyses. Results The scales were found to have sufficient to good internal consistency (mean Cronbach’s-α = 0.79) and test–retest reliability (mean correlation r = 0.76). Analyses-of-variance demonstrated significant differences between the scores of the mental, physical and healthy groups on most of the expected scales. These results were found both in groups defined by self-classification as well as in groups based on disease codes. Moreover, discriminant analyses revealed that the a priori classification of the respondents into three groups (mental, physical, healthy) for more than 75% of them corresponded with the classification on the basis of scale scores obtained from the questionnaire. Furthermore, limitations due to specific types of complaints (low back pain, fatigue, concentration problems) or diagnosed disorders (musculoskeletal disorders, reactive disorders, endogenous disorders) were clearly reflected in the scores of the related scales of the PFH. Conclusion The psychometric properties of the PFH with respect to reliability and validity were satisfactory. The PFH would appear to be an appropriate instrument for systematically measuring functional limitations in subjects on sick leave and in those receiving disability pensions, and could be used as a starting point in a disability claim procedure

Identification of serum angiopoietin-2 as a biomarker for clinical outcome of colorectal cancer patients treated with bevacizumab-containing therapy

BACKGROUND: The combination of chemotherapy with the vascular endothelial growth factor (VEGF) antibody bevacizumab is a standard of care in advanced colorectal cancer (CRC). However, biomarkers predicting outcome of bevacizumab-containing treatment are lacking. As angiopoietin-2 (Ang-2) is a key regulator of vascular remodelling in concert with VEGF, we investigated its role as a biomarker in metastatic CRC. METHODS: Serum Ang-2 levels were measured in 33 healthy volunteers and 90 patients with CRC. Of these, 34 had metastatic disease and received bevacizumab-containing therapy. To determine the tissue of origin of Ang-2, quantitative real-time PCR was performed on microdissected cryosections of human CRC and in a murine xenograft model of CRC using species-specific amplification. RESULTS: Ang-2 originated from the stromal compartment of CRC tissues. Serum Ang-2 levels were significantly elevated in patients with metastatic CRC compared with healthy controls. Amongst patients receiving bevacizumab-containing treatment, low pre-therapeutic serum Ang-2 levels were associated with a significant better response rate (82 vs 31%; P<0.01), a prolonged median progression-free survival (14.1 vs 8.5 months; P<0.01) and a reduction of 91% in the hazard of death (P<0.05). CONCLUSION: Serum Ang-2 is a candidate biomarker for outcome of patients with metastatic CRC treated with bevacizumab-containing therapy, and it should be further validated to customise combined chemotherapeutic and anti-angiogenic treatment. British Journal of Cancer (2010) 103, 1407-1414. doi: 10.1038/sj.bjc.6605925 www.bjcancer.com Published online 5 October 2010 (C) 2010 Cancer Research U