A
bstract
Sphaleron and instanton solutions of the Standard Model provide violation of baryon and lepton numbers and could lead to spectacular events at the LHC or future colliders. Certain models of ...new physics can also lead to sphaleron-like vacuum transitions. This nonperturbative physics could be relevant to the generation of the matter-antimatter asymmetry of the universe. We have developed BaryoGEN, an event generator that facilitates the exploration of sphaleron-like transitions in proton-proton collisions with minimal assumptions. BaryoGEN outputs standard Les Houches Event files that can be processed by PYTHIA, and the code is publicly available. We also discuss various approaches to experimental searches for such transitions in proton-proton collisions.
There are physiological reasons to expect an association between bone mineral density of the spine and hip and attachment loss. To this point, however, most studies have found no correlation.
The 135 ...patients in this report were part of a randomized controlled trial of estrogen replacement. All patients were in good oral health at entry and received annual oral prophylaxis as part of the study. Standard probing measurements were made with a pressure sensitive probe at 6 sites on each tooth. Bone mineral density was measured with dual-energy x-ray absorbtiometry at the lumbar spine (anterior-posterior and lateral) and proximal femur (neck, trochanter, intertrochanter, Ward's triangle, and total area). These procedures were performed at baseline and at annual intervals for 3 years.
Correlations between cross-sectional measurements of clinical attachment level and bone mineral density were very weak, and did not approach statistical significance (-0.06 < or =r < or =0.10, 0.15 < or =P < or =0.75). A few somewhat stronger correlations were found between longitudinal changes in bone mineral density and attachment (-0.20 < or = r < or =-0.02, 0.02 < or = P < or =0.81). Although the correlations in the longitudinal changes were weak, they were consistently in the direction of greater bone mineral density being associated with less attachment loss.
There is no clear association between clinical attachment level and bone mineral density of the lumbar spine and proximal femur, whether examined on a cross-sectional or longitudinal basis. Patterns in the data suggest there may be a weak association in the longitudinal changes.
We have previously reported that estrogen/hormone replacement therapy (E/HRT) has beneficial effects on oral bone density over 3 years and that calcium and vitamin D supplementation has a lesser ...effect. Here we report on mandibular bone mass for 49 women (of the original cohort of 135) who continued in an additional 2-year, open-label extension.
Postmenopausal women were randomly assigned to receive calcium and vitamin D plus E/HRT, or calcium and vitamin D only. Regression analysis of mandibular bone mass over time was performed for each woman.
Twenty-two of 26 women who took calcium and vitamin D plus E/HRT for 5 years had small mandibular bone mass increases (0.35 +/- 0.38%, P<0.001). Seventeen of 19 women who took only calcium and vitamin D for 3 years had increases in mandibular bone mass (0.74 +/- 0.89%, P<0.002). The largest gains in mandibular bone mass occurred during the first 3 years of the study.
The data of this study indicate that E/HRT and/or calcium and vitamin D may result in increases of mandibular bone mass in postmenopausal women. Because of the long-term risks associated with E/HRT, caution should be exercised in prescribing E/HRT for prevention of chronic menopausal conditions.
The relationship between loss of radiographic alveolar bone height and probing attachment loss has been studied by a number of investigators, with mixed results. Recent studies have found weak ...correlations and have suggested that the relationship between bone loss and attachment loss is complex, perhaps because changes in bone height and attachment level are separated in time.
The 85 patients in this report were part of a prospective estrogen replacement interventional study. All patients were in good oral health at entry and received annual oral prophylaxis as part of the study. Standard probing measurements were made with a pressure-sensitive probe at 6 sites on each tooth. Vertical bite-wing radiographs were taken of each patient, radiographs were digitized, and 6 linear measurements (corresponding to probing site measurements) were made from the cemento-enamel junction to the alveolar crest. These procedures were performed at baseline and at annual intervals; this study reports results after 2 years. Data were analyzed both by individual site and by averaging identical sites from all measured teeth for each patient.
Very weak direct relationships between change in alveolar bone height and change in attachment level were found in both the site data (r2=0.0022; P = 0.189) and the patient average data (r2=0.031; P= 0.104).
The changes in these patients were probably due to systemic changes in bone health rather than to periodontal disease. However, the weak correlations between changes in attachment level and bone height are similar to recent studies of periodontal disease. Our results support suggestions in the literature that the link between changes in attachment and alveolar bone height is complex, perhaps because changes in the 2 tissue types are separated by a considerable time delay.
Sphaleron and instanton solutions of the Standard Model provide violation of baryon and lepton numbers and could lead to spectacular events at the LHC or future colliders. Certain models of new ...physics can also lead to sphaleron-like vacuum transitions. This nonperturbative physics could be relevant to the generation of the matter-antimatter asymmetry of the universe. We have developed BaryoGEN, an event generator that facilitates the exploration of sphaleron-like transitions in proton-proton collisions with minimal assumptions. BaryoGEN outputs standard Les Houches Event files that can be processed by PYTHIA, and the code is publicly available. We also discuss various approaches to experimental searches for such transitions in proton-proton collisions.
Cathode strip chambers for the CMS endcap muon system Hauser, Jay
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/1996, Letnik:
384, Številka:
1
Journal Article
Recenzirano
In the CMS detector, the endcap muon system covers a large rapidity interval and has capability to trigger on muons down to very low transverse momenta for B physics. Cathode Strip Chambers (CSCs) ...have been chosen as the active detectors for this system, due to high rate and precision capabilities. The CMS endcap muon system is by far the largest deployment of CSC chambers and electronics so far envisioned. We describe the LHC environment and requirements for this system, the status of the design and prototyping of the CSC muon detectors, and the electronics required for readout and triggering. Of particular relevance for B physics is the planned capability to trigger on muons down to the momentum limits imposed by their ranges in steel. In the endcap system this corresponds to a very low
P
T.
The loss of ovarian function at menopause is associated with loss of postcranial and oral bone. Hormone/estrogen replacement therapy (HRT/ERT) has a positive effect on both postcranial and oral bone. ...The objective of the study was to determine if the positive effect of HRT/ERT on alveolar crest height (ACH) is generalized or site specific.
The sample consisted of 49 women who completed a 3-year, HRT/ERT prospective study. Cemento-enamel junction distances (ACH) were measured on digitized images of bitewing radiographs. Lumbar spine and proximal femur bone mineral densities (BMDs) were determined with dual-energy x-ray absorptiometric scans. Measurements were made at baseline and at the end of year 3. For the 3-year study period, mean change in ACH was determined for each patient. In addition, the sites with the greatest, second and third greatest ACH changes were determined for each patient. Correlations between changes in ACH (as determined by the various methods) and postcranial BMD were determined.
Mean ACH changes had an average correlation (r) of -0.24 with femoral and lumbar spine BMDs. Although the largest site-specific change in ACH resulted in a mean correlation of -0.21, the correlations for the second and third largest changes in ACH dropped to -0.15 and -0.12. Overall, the correlations for site-specific changes were substantively smaller than those for generalized change.
The data of this study indicate that ACH change attributable to HRT/ERT is generalized rather than site specific. Studies of the effect of HRT/ERT on ACH should employ multiple measurements to minimize measurement errors associated with site-specific measurements.
A large sample of D mesons, produced by the decay of the Ψ(3770) and observed by the Mark III detector at SPEAR, forms the basis for a study of the decays of charmed D+ and D0 mesons. Many ...Cabibbo-allowed and Cabibbo-suppressed decays are observed. When normalized by a new, absolute technique, the branching ratios appear significantly higher than those reported by previous experiments. No evidence is found for specific final states from D0 decay which are indicative of non-spectator W-exchange diagrams: limits are quoted. Finally, the inclusive semileptonic branching fractions of charged and neutral D mesons are measured by observation of electrons in the recoil from fully reconstructed hadronic D decays of known charm. By neglecting the contribution of Cabibbo-suppressed decays to the total decay widths, the ratio of these branching fractions can be interpreted as the ratio of D+ and D0 lifetimes, thus confirming the inequality of lifetimes observed by direct decay length experiments. The observed pattern of hadronic decays appears to favor modification of the spectator model over non-spectator processes as the main source of the lifetime difference.
Our objective was to test the association between cemento-enamel junction, alveolar-crest distance (CEJ-AC, as measured on digitized vertical bite-wing radiographs) and postcranial bone mineral ...density (BMD) relative to clinical, dietary, and demographic variables.
Data were collected in a cross-sectional study of 134 postmenopausal women. CEJ-AC distances were determined from digitized vertical bite-wing radiographs. Lumbar spine and proximal femur BMDs were determined from dual-energy x-ray absorptiometric scans. Correlation analysis and Student t tests were used to identify those variables most associated with CEJ-AC distance. The selected variables were modeled with a backward stepwise regression analysis, with CEJ-AC distance as the dependent variable.
Parity (number of pregnancies to term), cigarette smoking, and the interaction of lateral spine BMD with cigarette smoking were independent predictors of CEJ-AC distance (P < or =0.05). Statistical models containing these variables accounted for 19% of the variation in CEJ-AC distances.
CEJ-AC distance in postmenopausal women is the result of a complicated interaction of many effects, including but not limited to, parity, cigarette smoking, and skeletal BMD.
We conducted a 3-year, double-blind, randomized, placebo-controlled study to determine whether the positive effects of hormone/estrogen replacement therapy (H/ERT) on postcranial bone density are ...accompanied by similar positive effects on oral bone mass.
A total of 135 postmenopausal women (aged 41-70 years) with no evidence of moderate or severe periodontal disease were randomized to receive daily oral conjugated estrogen (Premarin; 0.625 mg) alone or in combination with medroxyprogesterone acetate (Prempro; 0.625 and 2.5 mg, respectively) or placebo. All subjects received calcium carbonate (1000 mg/d) and cholecalciferol (400 corrected IU/d) supplements. The primary efficacy end points were the changes in alveolar crest height and alveolar bone density. Alveolar crest height was measured on bite-wing radiographs, and changes in alveolar bone mass were assessed by means of digital-subtraction radiography. Postcranial bone density was measured in the lumbar spine and left proximal femur by means of dual-energy x-ray absorptiometry.
Hormone/estrogen replacement therapy significantly increased alveolar bone mass compared with placebo (+1.84% vs +0.95% P =.04), and tended to improve alveolar crest height (+4.83% vs +3.46% P =.34). Bone mineral density of the proximal femur significantly increased in the H/ERT compared with the placebo group (total proximal femur, +3.59% vs +0.22% P =.001; neck, +2.05% vs -0.34% P =.02; trochanter, +3.49% vs +0.08% P<.001), but not the lumbar spine (+1.01% vs +0.17% P =.39). Changes in alveolar bone mass correlated with bone density changes in the total femur (r = 0.28 P =.02) and femoral trochanter (r = 0.25 P =.04) in the H/ERT but not in the placebo group.
Postcranial and oral bone mass were increased in postmenopausal women receiving H/ERT. Improvement in oral bone health constitutes an additional benefit of H/ERT.
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