Information Content in B→VVB \to VV Decays and the Angular Moments Method

The time-dependent angular distributions of decays of neutral $B$ mesons into two vector mesons contain information about the lifetimes, mass differences, strong and weak phases, form factors, and CP violating quantities. A statistical analysis of the information content is performed by giving the ``information'' a quantitative meaning. It is shown that for some parameters of interest, the information content in time and angular measurements combined may be orders of magnitude more than the information from time measurements alone and hence the angular measurements are highly recommended. The method of angular moments is compared with the (maximum) likelihood method to find that it works almost as well in the region of interest for the one-angle distribution. For the complete three-angle distribution, an estimate of possible statistical errors expected on the observables of interest is obtained. It indicates that the three-angle distribution, unraveled by the method of angular moments, would be able to nail down many quantities of interest and will help in pointing unambiguously to new physics.Comment: LaTeX, 34 pages with 9 figure

Strong diamagnetic response and specific heat anomaly above T_c in underdoped La_(2-x)Sr_xCuO_4

By measuring AC susceptibility using a very low amplitude of the AC field (<1 mG) it is shown that underdoped samples of La_(2-x)Sr_xCuO_4 (LASCO), are diamagnetic in a temperature region above T_c up to a temperature T^*. This behavior is only observed with AC fields along the c-axis whereas for fields in the ab-plane no diamagnetism above Tc was detected. The diamagnetism is almost frequency independent in the frequency range 0.1-10 kHz. At T* a broad step anomaly in the specific heat is inferred through measurements of the elastic constant c33. We suggest that the observed diamagnetism and the anomaly in the elastic constant are associated with the existence of phase incoherent Cooper pairs between Tc and T*.Comment: 5 pages 7 figures, to appear in Phys. rev

The prognostic value of a nomogram for exercise capacity in women

BACKGROUND: Recent studies have demonstrated that exercise capacity is an independent predictor of mortality in women. Normative values of exercise capacity for age in women have not been well established. Our objectives were to construct a nomogram to permit determination of predicted exercise capacity for age in women and to assess the predictive value of the nomogram with respect to survival. METHODS: A total of 5721 asymptomatic women underwent a symptom-limited, maximal stress test. Exercise capacity was measured in metabolic equivalents (MET). Linear regression was used to estimate the mean MET achieved for age. A nomogram was established to allow the percentage of predicted exercise capacity to be estimated on the basis of age and the exercise capacity achieved. The nomogram was then used to determine the percentage of predicted exercise capacity for both the original cohort and a referral population of 4471 women with cardiovascular symptoms who underwent a symptom-limited stress test. Survival data were obtained for both cohorts, and Cox survival analysis was used to estimate the rates of death from any cause and from cardiac causes in each group. RESULTS: The linear regression equation for predicted exercise capacity (in MET) on the basis of age in the cohort of asymptomatic women was as follows: predicted MET = 14.7 - (0.13 x age). The risk of death among asymptomatic women whose exercise capacity was less than 85 percent of the predicted value for age was twice that among women whose exercise capacity was at least 85 percent of the age-predicted value (P&lt;0.001). Results were similar in the cohort of symptomatic women. CONCLUSIONS: We have established a nomogram for predicted exercise capacity on the basis of age that is predictive of survival among both asymptomatic and symptomatic women. These findings could be incorporated into the interpretation of exercise stress tests, providing additional prognostic information for risk stratification

SPECT perfusion imaging in the diagnosis of Alzheimer's disease: a clinical-pathologic study

Objective: Numerous studies have suggested that temporoparietal hypoperfusion seen on brain imaging with SPECT may be useful in diagnosing AD during life. However, these studies have often been limited by lack of pathologic validation and unrepresentative samples. The authors performed this study to determine whether SPECT imaging provides diagnostically useful information in addition to that obtained from a clinical examination. Methods: Clinical data and SPECT images were collected prospectively, and patients were followed to autopsy. Clinical history, pathologic findings, and SPECT images were each evaluated by raters blind to other features, and clinical and SPECT diagnoses were compared with pathologic diagnoses. The study population consisted of 70 patients with dementia, followed to autopsy; 14 controls followed to autopsy; and 71 controls (no autopsy performed). The primary outcome was the likelihood of a pathologic diagnosis of AD given a positive clinical diagnosis, a positive SPECT diagnosis, and both. Results: When all participants (patients and controls) were included in the analysis, the clinical diagnosis of “probable” AD was associated with an 84% likelihood of pathologic AD. A positive SPECT scan raised the likelihood of AD to 92%, whereas a negative SPECT scan lowered the likelihood to 70%. SPECT was more useful when the clinical diagnosis was “possible” AD, with the likelihood of 67% without SPECT, 84% with a positive SPECT, and 52% with a negative SPECT. Similar results were found when only patients with dementia were included in the analysis. Conclusions: In the evaluation of dementia, SPECT imaging can provide clinically useful information indicating the presence of AD in addition to the information that is obtained from clinical evaluation

SPECT brain imaging in epilepsy: a meta-analysis

Michael D. Devous, Sr., Ronald A. Thisted, Gillian F. Morgan, Robert F. Leroy and Christopher C. Row