Search results for "Equation"
showing 10 items of 4219 documents
A series expansion of the extended Debye-H�ckel equation and application to linear prediction of stability constants
1996
The Debye-Hückel semiempirical extended equation is frequently used to calculate activity coefficients of chemical species and equilibrium constants at ionic strengths different from those used in their experimental evaluation. A series expansion of the extended Debye-Hückel equation is proposed here and checked with experimental data taken from the literature. The expansion is linear in the ionic parameters and yields a geometrical series which converges rapidly and that enables the accurate calculation of interpolated and extrapolated activity coefficients and equilibrium constants by simple and multiple linear regression without previous knowledge of the ionic parameters.
Adaptive dual control in one biomedical problem
2003
In this paper, the following biomedical problem is considered. People are subjected to a certain chemotherapeutic treatment. The optimal dosage is the maximal dose for which an individual patient will have toxicity level that does not cross the allowable limit. We discuss sequential procedures for searching the optimal dosage, which are based on the concept of dual control and the principle of optimality. According to the dual control theory, the control has two purposes that might be conflicting: one is to help learning about unknown parameters and/or the state of the system (estimation); the other is to achieve the control objective. Thus the resulting control sequence exhibits the closed…
Adaptive neuro-fuzzy inference system for kinematics solutions of redundant robots
2016
This written paper presents aspects concerning the implementation of the Adaptive Neuro-Fuzzy Inference System (ANFIS) in the resolution of a redundant serial robot kinematics. The kinematics solutions are divided into two categories: direct kinematics solutions and inverse kinematics solutions. To be able to control a robot the most important solutions are the ones for the inverse kinematics since one knows the position and the final orientation of the end effector and needs to determine the relative displacement or movements into the robot couplings. To obtain the optimal solutions for the inverse kinematics of a redundant robot the mathematical equations were based onto the redundancy ci…
Prediction of embryo survival and live birth rates after cryotransfers of vitrified blastocysts
2020
Which pre-vitrification parameters are the most predictive of survival and live birth in vitrified-warmed blastocyst transfer cycles?A retrospective study including 11,936 warmed blastocysts. Pre-vitrification morphological parameters analysed for blastocysts included day of vitrification; blastocyst expansion degree; trophoectoderm grade (A, B and C); and inner cell mass grade (A, B and C). Univariate and multivariate generalized estimating equations models were used to analyse survival, clinical pregnancy and live birth rate. A stepwise regression analysis was conducted to select and classify by order which outcomes were the most predictive.The odds of survival increased almost twice for …
Translation, adaptation and psychometric validation of the preterm birth experience and satisfaction scale (P-BESS) into Spanish.
2018
Abstract Background Preterm labour and birth are two of the most important issues in perinatal care. The birth of a preterm baby is often a stressful and traumatic time for parents. Assessment of satisfaction with maternity services is crucial and questionnaires are the most common method as long as they are well-constructed. Only one, The Preterm Birth Experience and Satisfaction Scale (P-BESS), developed in United Kingdom, has been designed for this specific birth type. Objectives To translate, transculturally adapt and assess the psychometric properties of the P-BESS into Spanish. Design Cross-sectional study. Setting Maternity unit of a tertiary level hospital in Spain. Participants A t…
Dynamic relations among COVID-19-related media exposure and worries during the COVID-19 pandemic
2021
Objectives: This study investigated how COVID-19-related media exposure during the COVID-19 crisis was related to same-day and next-day COVID-19-related worries. Design: A 21-day diary study was conducted between late March and late April 2020 in Germany. Main Outcome Measures: Hypotheses were tested in a sample of 561 participants (Mage = 42.79, SDage = 6.12). Every evening, participants indicated their exposure to COVID-19-related media (e.g., TV, print, online) and their COVID-19-related worries. Results: Same-day analyses showed that participants reported more COVID-19-related worries on days with higher exposure to COVID-19-related media. Dynamical structural equation models provided e…
Psychometric properties of the "Spanish Burnout Inventory" in Chilean professionals working to physical disabled people.
2011
While the most commonly employed burnout measure has been the Maslach Burnout Inventory (MBI), researchers have been troubled by some of the psychometric limitations of this instrument. The aim of this study was to analyze the psychometric properties of the “Spanish Burnout Inventory” (SBI). The psychometric properties were analysed with data from a sample of 277 Chilean professionals working to physical disabled people. The psychometric properties of the SBI were examined through the following analyses: confirmatory factor analysis, reliability Cronbach's alpha, and concurrent validity with the MBI. The hypothesized four factor model obtained an adequate data fit for the sample (X2(164) = …
Validation of a Short Form of Job Crafting Scale in a Spanish Sample
2018
AbstractApplications of job crafting are widespread in the professional practice. In an attempt to measure this phenomenon, Tims, Bakker and Derks (2012) developed a Job Crafting Scale based on the Job Demand-Resources model (JD-R) and validated it in a Dutch sample. However, its application to other cultural contexts presented some difficulties. The present work aimed to validate a shorter version of scale by Tims et al. (2012) in a Spanish sample (n = 1,647). The data were randomly split in two independent subsamples (Sample 1: Explorative; Sample 2: Confirmative). The exploratory factor analysis showed a three-factor structure. Through a confirmatory factor analysis, the four-dimensional…
Teacher Support Resources, Need Satisfaction and Well-Being.
2015
AbstractBased on Job Demands-Resources Model (JD-R), this study examines the relationships among teacher support resources, psychological need satisfaction, engagement and burnout in a sample of 282 Spanish secondary school teachers. Nine teacher psychological needs were identified based on the study of Bess and on the Self-Determination Theory (SDT). Self-report questionnaires were used to measure the constructs selected for this study and their interrelationships were examined by structural equation modeling. The results reveal a good model fit to the data (NNFI = .88; CFI = .90; GFI = .90; RMSEA = .061). The analyses indicate a positive and significant effect of latent variable Psycholog…
Country, Sex, and Parent Occupational Status: Moderators of the Continuity of Aggression from Childhood to Adulthood
2014
Using data from two American and one Finnish long-term longitudinal studies, we examined continuity of general aggression from age 8 to physical aggression in early adulthood (age 21–30) and whether continuity of aggression differed by country, sex, and parent occupational status. In all samples, childhood aggression was assessed via peer nominations and early adulthood aggression via self-reports. Multi-group structural equation models revealed significant continuity in aggression in the American samples but not in the Finnish sample. These relations did not differ by sex but did differ by parent occupational status: whereas there was no significant continuity among American children from …