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Consequences of variable selection on the interpretation of the results in multiple linear regression. A priori or a posteriori variable selection is a common practise in multiple linear regression. The user is however not always aware of the consequences on the results due to this variable selection. In this note, the presence of omission bias and selection bias is explained by means of a Monte Carlo experiment. The consequences of variable selection on the regression coefficients and on the predicted values are then analysed. The user’s attention is drawn to the risk of misinterpretation of the regression coefficients, specially after variable selection. On the other hand, the consequences of variable selection on the predicted values of the response variable are rather limited, at least for the given example.

The Observatory of Food Consumption in the Walloon Region (Belgium): why, how ? The behaviour of food products consumers is observed by several organisms. This paper gives some informations about situations abroad and in Belgium. It describes the Observatory of Food Consumption established in the Walloon Region.

Use of bootstrap for statistical problems related to estimation of parameters. Use of bootstrap for statistical problems related to estimation of parameters. This paper describes bootstrapping for the estimation of the standard error and the bias of an estimator and for computing confidence intervals. The methods are illustrated by an example.

Research-based education is a long-standing tradition at the University of Tartu (UT). Basic knowledge of electrochemistry and the principles of developing electrochemical devices have been taught and implemented at UT since 1960. For instance, during then, self-made alkaline electrolysers were used to generate hydrogen. The hydrogen was further purified and used to saturate aqueous and non-aqueous electrolytes. The fundamental electrochemical research has formed a solid background on which the development of supercapacitors and Na+-ion or Li+-ion batteries is based today. Since 1991, the Ph.D., MSc and undergraduate students have investigated the properties of high surface–area carbon materials in non-aqueous electrolytes to develop energy conversion and storage devices with high energy and power density. Moreover, porous thin-film complex metal hydride–based hydrogen storage devices are also under study. The research of solid oxide fuel cells (SOFC) and polymer electrolyte membrane fuel cells (PEMFC) began at the UT in 2001 and 2010, respectively. Based on the collected knowledge, a sustainable green electricity and hydrogen generation-storage complex (GEHGSC) was constructed, consisting of solar cells and fuel cells for electricity generation, batteries for storage and electrolysers for hydrogen generation. The main aim of GEHGSC is to educate students, young scientists and local authorities specialized in sustainable energy technologies and applied electrochemistry. Electrolyzed hydrogen has been used for experimental testing of SOFC and PEMFC, produced at the Institute of Chemistry. The 300 bar hydrogen compressor has been installed, and thereafter, the PEMFC-powered self-driving car Iseauto, completed by contract for Auve Tech OÜ, has been fuelled with hydrogen produced by GEHGSC. [ABSTRACT FROM AUTHOR]

Twelve Gossypium genotypes (species, fertile interspecific allotetraploid and allohexaploid hybrids, backcross progeny of interspecific hybrids) characterized by drastic differences in their seed gossypol content were used to design a visual quantification method of the gossypol concentration in cotton seeds. After developing an high performance liquid chromatography (HPLC) method that allowed measurement of gossypol content in single seed samples, the results of 123 HPLC analyses carried out seed-by-seed were compared with different parameters characterizing the level of gossypol glands in the seed. A significant correlation was found between the gossypol content %G determined on single seeds by HPLC and the number N of gossypol glands per seed section area (S, expressed in [mm.sup.2]), leading to the establishment of the following model: %G = [b.sub.i] (N/S), where the regression coefficient [b.sub.i] depends on the cotton genotype considered. The estimation of %G directly from N/S is a rapid and accurate method which can be used in breeding programs to screen the progeny of cotton genotypes showing a high segregation for their seed gossypol content., ONE OF THE MAIN TRAITS of Gossypium L. is the presence of pigment glands throughout the plant (Altman et al., 1990). Gossypol, a triterpenoid aldehyde, and its derivatives are predominant [...]

We focus on the analysis and design of two different sliding mode observers for dynamic Takagi--Sugeno (TS) fuzzy systems. A nonlinear system of this class is composed of multiple affine local linear models that are smoothly interpolated by weighting functions resulting from a fuzzy partitioning of the state space of a given nonlinear system subject to observation. The Takagi-Sugeno fuzzy system is then an accurate approximation of the original nonlinear system. Our approach to the analysis and design of observers for Takagi-Sugeno fuzzy systems is based on extending sliding mode observer schemes to the case of interpolated multiple local affine linear models. Thus, our main contribution is nonlinear observers analysis and design methods that can effectively deal with model/plant mismatches. Furthermore, we consider the difficult case when the weighting functions in the Takagi--Sugeno fuzzy system depend on the estimated state. Index Terms--Dominant linear models, fuzzy sliding mode observers, interpolation of multiple linear local models, Luenberger fuzzy observers, Takagi-Sugeno (TS) fuzzy systems.

Microporous carbon materials are promising for hydrogen storage due to their structural variety, high specific surface area, large pore volume and relatively low cost. Carbide-derived carbons are highly valued as model materials because their porous structure is fine-tuned through the choice of the precursor carbide and the synthesis route. This study investigates H2 adsorption in three carbide derived carbons with well-defined pores and pore size distributions with quasi- and inelastic neutron scattering methods. Concerning previous studies, a wider neutron energy transfer window is investigated, and a detailed quantitative evaluation of the graphitic structure is presented. The graphitic structure of the carbon is shown to influence the speed of the ortho-to-para transition of H2. Namely, the ortho-para transition was the slowest in carbon derived from TiC, which also had the smallest average stacking size of graphene layers. The possibility to inhibit the ortho-para transition in cryo-adsorption devices is sought after to mitigate the evaporation of H2 during storage. In addition, the self-diffusion of H2 in different timescales is detected in carbon derived from Mo2C, demonstrating the usefulness of obtaining data in a wide energy window.

Background: Among women aged 50 to 59 years at baseline in the Women's Health Initiative (WHI) Estrogen‐Alone (E‐Alone) trial, randomization to conjugated equine estrogen‐alone versus placebo was associated with lower risk of myocardial infarction and mortality, and, in an ancillary study, the WHI‐CACS (WHI Coronary Artery Calcification Study) with lower CAC, measured by cardiac computed tomography ≈8.7 years after baseline randomization. We hypothesized that higher CAC would be related to post‐trial coronary heart disease (CHD), cardiovascular disease (CVD), and total mortality, independent of baseline randomization or risk factors. Methods and Results: WHI‐CACS participants (n=1020) were followed ≈8 years from computed tomography scan in 2005 (mean age=64.4) through 2013 for incident CHD (myocardial infarction and fatal CHD, n=17), CVD (n=69), and total mortality (n=55). Incident CHD and CVD analyses excluded women with CVD before scan (n=89). Women with CAC=0 (n=54%) had very low age‐adjusted rates/1000 person‐years of CHD (0.91), CVD (5.56), and mortality (3.45). In comparison, rates were ≈2‐fold higher for women with any CAC (>0). Associations were not modified by baseline randomization to conjugated equine estrogen–alone versus placebo. Adjusted for baseline randomization and risk factors, the hazard ratio (95% confidence interval) for CAC >100 (19%) was 4.06 (2.11, 7.80) for CVD and 2.70 (1.26, 5.79) for mortality. Conclusions: Among a subset of postmenopausal women aged 50 to 59 years at baseline in the WHI E‐Alone Trial, CAC at mean age of 64 years was strongly related to incident CHD, CVD, and to total mortality over ≈8 years, independent of baseline randomization to conjugated equine estrogen–alone versus placebo or CVD risk factors. Clinical Trial Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT00000611.

The electrochemical impedance spectroscopy, the cyclic voltammetry, and the constant power charge/discharge methods have been applied to establish the electrochemical characteristics for the electrical double-layer capacitor consisting of the 1 M (C2H5)3CH3NBF4 electrolyte in acetonitrile. The microporous carbon electrodes prepared from D-(+)-glucose by the hydrothermal carbonization method and subsequent pyrolysis and carbon dioxide activation steps. The total Brunauer-Emmett-Teller specific surface area (SBET ≤ 1539 m² g-1), micropore surface area (Smicro ≤ 1534 m² g-1), total pore volume (Vtot ≤ 0.694 cm³ g-1) and the size distribution of the pores, obtained from the N2 sorption data and using the non-local density functional theory, have been correlated with the electrochemical characteristics for electrical double-layer capacitors as the region of ideal polarizability (ΔE ≤ 3.0 V), characteristic time constant (0.34 s) and the high series capacitance (126 F g-1), dependent on the carbon activation conditions, have been calculated. [ABSTRACT FROM AUTHOR]