Measures of health and disease in Africa: are current methods giving us useful information about trends in cardiovascular diseases?

An enormous burst of interest in the public health burden from chronic disease in Africa has emerged as a consequence of efforts to estimate global population health. Detailed estimates are now published for Africa as a whole and each country on the continent. These data have formed the basis for warnings about sharp increases in cardiovascular disease (CVD) in the coming decades. In this essay we briefly examine the trajectory of social development on the continent and its consequences for the epidemiology of CVD and potential control strategies. Since full vital registration has only been implemented in segments of South Africa and the island nations of Seychelles and Mauritius - formally part of WHO-AFRO - mortality data are extremely limited. Numerous sample surveys have been conducted but they often lack standardization or objective measures of health status. Trend data are even less informative. However, using the best quality data available, age-standardized trends in CVD are downward, and in the case of stroke, sharply so. While acknowledging that the extremely limited available data cannot be used as the basis for inference to the continent, we raise the concern that general estimates based on imputation to fill in the missing mortality tables may be even more misleading. No immediate remedies to this problem can be identified, however bilateral collaborative efforts to strength local educational institutions and governmental agencies rank as the highest priority for near term development.

Do different measures of early life socioeconomic circumstances predict adult mortality? Evidence from the British Whitehall II and French GAZEL studies

BACKGROUND: Father's occupational position, education and height have all been used to examine the effects of adverse early life socioeconomic circumstances on health, but it remains unknown whether they predict mortality equally well. METHODS: We used pooled data on 18,393 men and 7060 women from the Whitehall II and GAZEL cohorts to examine associations between early life socioeconomic circumstances and all-cause and cause-specific mortality. RESULTS: During the 20-y follow-up period, 1487 participants died. Education had a monotonic association with all mortality outcomes; the age, sex and cohort-adjusted HR for the lowest versus the highest educational group was 1.45 (95% CI 1.24 to 1.69) for all-cause mortality. There was evidence of a U-shaped association between height and all-cause, cancer and cardiovascular mortality robust to adjustment for the other indicators (HR 1.41, 95% CI 1.03 to 1.93 for those shorter than average and HR 1.36, 95% CI 0.98 to 1.88 for those taller than average for cardiovascular mortality). Greater all-cause and cancer mortality was observed in participants whose father's occupational position was manual rather than non-manual (HR 1.11, 95% CI 1.00 to 1.23 for all-cause mortality), but the risks were attenuated after adjusting for education and height. CONCLUSIONS: The association between early life socioeconomic circumstances and mortality depends on the socioeconomic indicator used and the cause of death examined. Height is not a straightforward measure of early life socioeconomic circumstances as taller people do not have a health advantage for all mortality outcomes.

Resting-brain functional connectivity predicted by analytic measures of network communication.

The complex relationship between structural and functional connectivity, as measured by noninvasive imaging of the human brain, poses many unresolved challenges and open questions. Here, we apply analytic measures of network communication to the structural connectivity of the human brain and explore the capacity of these measures to predict resting-state functional connectivity across three independently acquired datasets. We focus on the layout of shortest paths across the network and on two communication measures-search information and path transitivity-which account for how these paths are embedded in the rest of the network. Search information is an existing measure of information needed to access or trace shortest paths; we introduce path transitivity to measure the density of local detours along the shortest path. We find that both search information and path transitivity predict the strength of functional connectivity among both connected and unconnected node pairs. They do so at levels that match or significantly exceed path length measures, Euclidean distance, as well as computational models of neural dynamics. This capacity suggests that dynamic couplings due to interactions among neural elements in brain networks are substantially influenced by the broader network context adjacent to the shortest communication pathways.

Analytical Measures of Learners' Written Interlanguage

This paper aims at reconsidering some analytical measures to best encapsulate the interlanguage, in writing, of young beginner learners of English as a foreign language in the light of previous and work-in-progress research conducted within the BAF project, and in particular, whether clause and sentence length should be best viewed as a fluency or syntactic complexity measusre or as part of a different construct. In the light of a factor analysis (Navés, forthcoming) and multivariate and correlation studies (Navés et al. 2003, Navés, 2006, Torres et al. 2006) it becomes clear that the relationship between different analytical measures is also dependent on learner¿s cognitive maturity (age) and proficiency (amount of instruction). Finally, clause and sentence length should not be viewed as either a fluency or sytactic complexity measure but as part of a different construct. It is concluded that further research using regression analysis and cluster analysis is neeed in order to identify and validate the constructs of the writing components and their measurements.

Measures of ionicity of alkaline-earth oxides from the analysis of ab initio cluster wave functions

We present an analysis of the M-O chemical bonding in the binary oxides MgO, CaO, SrO, BaO, and Al2O3 based on ab initio wave functions. The model used to represent the local environment of a metal cation in the bulk oxide is an MO6 cluster which also includes the effect of the lattice Madelung potential. The analysis of the wave functions for these clusters leads to the conclusion that all the alkaline-earth oxides must be regarded as highly ionic oxides; however, the ionic character of the oxides decreases as one goes from MgO, almost perfectly ionic, to BaO. In Al2O3 the ionic character is further reduced; however, even in this case, the departure from the ideal, fully ionic, model of Al3+ is not exceptionally large. These conclusions are based on three measures, a decomposition of the Mq+-Oq- interaction energy, the number of electrons associated to the oxygen ions as obtained from a projection operator technique, and the analysis of the cation core-level binding energies. The increasing covalent character along the series MgO, CaO, SrO, and BaO is discussed in view of the existing theoretical models and experimental data.

Analytical Measures of Learners' Written Interlanguage

This paper aims at reconsidering some analytical measures to best encapsulate the interlanguage, in writing, of young beginner learners of English as a foreign language in the light of previous and work-in-progress research conducted within the BAF project, and in particular, whether clause and sentence length should be best viewed as a fluency or syntactic complexity measusre or as part of a different construct. In the light of a factor analysis (Navés, forthcoming) and multivariate and correlation studies (Navés et al. 2003, Navés, 2006, Torres et al. 2006) it becomes clear that the relationship between different analytical measures is also dependent on learner¿s cognitive maturity (age) and proficiency (amount of instruction). Finally, clause and sentence length should not be viewed as either a fluency or sytactic complexity measure but as part of a different construct. It is concluded that further research using regression analysis and cluster analysis is neeed in order to identify and validate the constructs of the writing components and their measurements.

Do Objective Measures of Blood Alcohol Concentrations Make More Sense than Self-reports in Emergency Department Studies?

Purpose: Concerns about self-reports have led to calls for objective measures of blood alcohol concentration (BAC). The present study compared objective measures with self-reports. Methods: BAC from breath or blood samples were obtained from 272 randomly sampled injured patients who were admitted to a Swiss emergency department (ED). Self-reports were compared a) between those providing and refusing a BAC test, and b) to estimated peak BAC (EPBAC) values based on BACs using the Widmark formula. Results: Those providing BACs were significantly (P < 0.05) younger, more often male, and less often reported alcohol consumption before injury, but consumed higher quantities when drinking. Eighty-eight percent of those with BAC measures gave consistent reports (positive or negative). Significantly more patients reported consumption with negative BAC measures (N = 29) than vice versa (N = 3). Duration of consumption and times between injury and BAC measurement predicted EPBAC better than did the objective BAC measure. Conclusions: There is little evidence that patients who provide objective BAC measures deliberately conceal consumption. ED studies must rely on self-reports, eg, take the time period between injury and ED admission into account. Clearly, objective measures are of clinical relevance, eg, to provide optimal treatment in the ED. However, they may be less relevant to establishing effects in an epidemiologic sense, such as estimating risk relationships. In this respect, efforts to increase the validity and reliability of self-reports should be preferred over the collection of additional objective measures.

Intracranial Aneurysm Rupture Is Predicted by Measures of Solar Activity.

OBJECTIVE: The cause precipitating intracranial aneurysm rupture remains unknown in many cases. It has been observed that aneurysm ruptures are clustered in time, but the trigger mechanism remains obscure. Because solar activity has been associated with cardiovascular mortality and morbidity, we decided to study its association to aneurysm rupture in the Swiss population. METHODS: Patient data were extracted from the Swiss SOS database, at time of analysis covering 918 consecutive patients with angiography-proven aneurysmal subarachnoid hemorrhage treated at 7 Swiss neurovascular centers between January 1, 2009, and December 31, 2011. The daily rupture frequency (RF) was correlated to the absolute amount and the change in various parameters of interest representing continuous measurements of solar activity (radioflux [F10.7 index], solar proton flux, solar flare occurrence, planetary K-index/planetary A-index, Space Environment Services Center [SESC] sunspot number and sunspot area) using Poisson regression analysis. RESULTS: During the period of interest, there were 517 days without recorded aneurysm rupture. There were 398, 139, 27, 12, 1, and 1 days with 1, 2, 3, 4, 5, and 6 ruptures per day. Poisson regression analysis demonstrated a significant correlation of F10.7 index and RF (incidence rate ratio [IRR] = 1.006303; standard error (SE) 0.0013201; 95% confidence interval (CI) 1.003719-1.008894; P < 0.001), according to which every 1-unit increase of the F10.7 index increased the count for an aneurysm to rupture by 0.63%. A likewise statistically significant relationship of both the SESC sunspot number (IRR 1.003413; SE 0.0007913; 95% CI 1.001864-1.004965; P < 0.001) and the sunspot area (IRR 1.000419; SE 0.0000866; 95% CI 1.000249-1.000589; P < 0.001) emerged. All other variables analyzed showed no significant correlation with RF. CONCLUSIONS: We found greater radioflux, SESC sunspot number, and sunspot area to be associated with an increased count of aneurysm rupture. The clinical meaningfulness of this statistical association must be interpreted carefully and future studies are warranted to rule out a type-1 error.

Many valued algebraic structures as measures of comparison

This thesis studies the properties and usability of operators called t-norms, t-conorms, uninorms, as well as many valued implications and equivalences. Into these operators, weights and a generalized mean are embedded for aggregation, and they are used for comparison tasks and for this reason they are referred to as comparison measures. The thesis illustrates how these operators can be weighted with a differential evolution and aggregated with a generalized mean, and the kinds of measures of comparison that can be achieved from this procedure. New operators suitable for comparison measures are suggested. These operators are combination measures based on the use of t-norms and t-conorms, the generalized 3_-uninorm and pseudo equivalence measures based on S-type implications. The empirical part of this thesis demonstrates how these new comparison measures work in the field of classification, for example, in the classification of medical data. The second application area is from the field of sports medicine and it represents an expert system for defining an athlete's aerobic and anaerobic thresholds. The core of this thesis offers definitions for comparison measures and illustrates that there is no actual difference in the results achieved in comparison tasks, by the use of comparison measures based on distance, versus comparison measures based on many valued logical structures. The approach has been highly practical in this thesis and all usage of the measures has been validated mainly by practical testing. In general, many different types of operators suitable for comparison tasks have been presented in fuzzy logic literature and there has been little or no experimental work with these operators.

Comparison measures of maps generated by geostatistical methods

This study uses several measures derived from the error matrix for comparing two thematic maps generated with the same sample set. The reference map was generated with all the sample elements and the map set as the model was generated without the two points detected as influential by the analysis of local influence diagnostics. The data analyzed refer to the wheat productivity in an agricultural area of 13.55 ha considering a sampling grid of 50 x 50 m comprising 50 georeferenced sample elements. The comparison measures derived from the error matrix indicated that despite some similarity on the maps, they are different. The difference between the estimated production by the reference map and the actual production was of 350 kilograms. The same difference calculated with the mode map was of 50 kilograms, indicating that the study of influential points is of fundamental importance to obtain a more reliable estimative and use of measures obtained from the error matrix is a good option to make comparisons between thematic maps.

Qualitative Characteristics and Quantitative Measures of Solution's Reliability in Discrete Optimization: Traditional Analytical Approaches, Innovative Computational Methods and Applicability

The purpose of this thesis is twofold. The first and major part is devoted to sensitivity analysis of various discrete optimization problems while the second part addresses methods applied for calculating measures of solution stability and solving multicriteria discrete optimization problems. Despite numerous approaches to stability analysis of discrete optimization problems two major directions can be single out: quantitative and qualitative. Qualitative sensitivity analysis is conducted for multicriteria discrete optimization problems with minisum, minimax and minimin partial criteria. The main results obtained here are necessary and sufficient conditions for different stability types of optimal solutions (or a set of optimal solutions) of the considered problems. Within the framework of quantitative direction various measures of solution stability are investigated. A formula for a quantitative characteristic called stability radius is obtained for the generalized equilibrium situation invariant to changes of game parameters in the case of the H¨older metric. Quality of the problem solution can also be described in terms of robustness analysis. In this work the concepts of accuracy and robustness tolerances are presented for a strategic game with a finite number of players where initial coefficients (costs) of linear payoff functions are subject to perturbations. Investigation of stability radius also aims to devise methods for its calculation. A new metaheuristic approach is derived for calculation of stability radius of an optimal solution to the shortest path problem. The main advantage of the developed method is that it can be potentially applicable for calculating stability radii of NP-hard problems. The last chapter of the thesis focuses on deriving innovative methods based on interactive optimization approach for solving multicriteria combinatorial optimization problems. The key idea of the proposed approach is to utilize a parameterized achievement scalarizing function for solution calculation and to direct interactive procedure by changing weighting coefficients of this function. In order to illustrate the introduced ideas a decision making process is simulated for three objective median location problem. The concepts, models, and ideas collected and analyzed in this thesis create a good and relevant grounds for developing more complicated and integrated models of postoptimal analysis and solving the most computationally challenging problems related to it.

Body composition measures of obese adolescents by the deuterium oxide dilution method and by bioelectrical impedance

The objectives of the present study were to describe and compare the body composition variables determined by bioelectrical impedance (BIA) and the deuterium dilution method (DDM), to identify possible correlations and agreement between the two methods, and to construct a linear regression model including anthropometric measures. Obese adolescents were evaluated by anthropometric measures, and body composition was assessed by BIA and DDM. Forty obese adolescents were included in the study. Comparison of the mean values for the following variables: fat body mass (FM; kg), fat-free mass (FFM; kg), and total body water (TBW; %) determined by DDM and by BIA revealed significant differences. BIA overestimated FFM and TBW and underestimated FM. When compared with data provided by DDM, the BIA data presented a significant correlation with FFM (r = 0.89; P < 0.001), FM (r = 0.93; P < 0.001) and TBW (r = 0.62; P < 0.001). The Bland-Altman plot showed no agreement for FFM, FM or TBW between data provided by BIA and DDM. The linear regression models proposed in our study with respect to FFM, FM, and TBW were well adjusted. FFM obtained by DDM = 0.842 x FFM obtained by BIA. FM obtained by DDM = 0.855 x FM obtained by BIA + 0.152 x weight (kg). TBW obtained by DDM = 0.813 x TBW obtained by BIA. The body composition results of obese adolescents determined by DDM can be predicted by using the measures provided by BIA through a regression equation.