Search results for "longitudinal"
showing 10 items of 1501 documents
The Evolution of Loyalty Intentions
2006
The drivers of customer loyalty intentions are dynamic. What remains unclear is how these intentions evolve through the introduction and growth phases of a life cycle. Using a longitudinal study of cellular phone customers, the authors demonstrate that loyalty intentions are a function of perceived value early in the life cycle. Over time, more affective attitudes toward the brand and the relationship with the company come to mediate the effects of value on intentions. The results suggest that from the introduction to the growth stage of a life cycle, managers must adapt from improving value per se to measuring and managing relationships and brands directly.
Quantification of Plasma Sprayed Coating Adhesion Using Pulsed Laser Induced Decohesion Technique
2001
Abstract The aim of the present study is to compare a laser ultrasonic technique with a conventional indentation test for the determination of intrinsic properties and the adhesion of alumina coatings, of different thicknesses (30–350 µm), deposited on stainless steel substrates by atmospheric plasma spraying (APS). For this purpose, a pulsed Nd:YAG laser is used to irradiate the coated specimens, and the ultrasonic waves generated by the laser are recorded at the epicenter using a laser interferometer. In the thermoelastic regime, the good agreement between the experiment and computation allows determination of the longitudinal wave velocity as well as the Young's modulus of the oxide coat…
Nature of water-biochar interface interactions
2012
A poplar biochar obtained by an industrial gasification process was saturated with water and analyzed using fast field cycling (FFC) NMR relaxometry in a temperature range between 299 and 353 K. Results revealed that the longitudinal relaxation rate increased with the increment of the temperature. This behavior was consistent with that already observed for paramagnetic inorganic porous media for which two different relaxation mechanisms can be accounted for: outer- and inner-sphere mechanisms. The former is due to water diffusing from the closest approach distance to infinity, whereas the second is due to water interacting by nonconventional H-bonds to the porous surface of the solid materi…
A Standardised Approach to the Biomechanical Evaluation of Tracheal Grafts
2021
[EN] The ideal tracheal substitute must have biomechanical properties comparable to the native trachea, but currently there is no standardised approach to evaluating these properties. Here we propose a novel method for evaluating and comparing the properties of tracheal substitutes, thus systematising both measurement and data curation. This system was tested by comparing native rabbit tracheas to frozen and decellularised specimens and determining the histological characteristics of those specimens. We performed radial compression tests on the anteroposterior tracheal axis and longitudinal axial tensile tests with the specimens anastomosed to the jaw connected to a measuring system. All ca…
Influence of laser beam profile on the generation of ultrasonic waves
2011
The different ultrasonic fields generated in metallic materials by a laser beam with flat and Gaussian profile are investigated experimentally and using the finite element method (FEM). A high power laser beam irradiating a solid surface produces elastic waves with a mechanics that depends on many parameters, including the profile of the laser beam. The influence of the beam profile is investigated with the FEM analysis, considering the temperature dependence of material properties.
The Impact of Internet and Social Media Use on Well-Being
2021
The present research examines the longitudinal average impact of frequency of use of Internet and social networking sites (SNS) on subjective well-being of adolescents in Germany. Based on five-wave panel data that cover a period of nine years, we disentangle between-person and within-person effects of media use on depressive symptomatology and life satisfaction as indicators of subjective well-being. Additionally, we control for confounders such as TV use, self-esteem, and satisfaction with friends. We found that frequency of Internet use in general and use of SNS in particular is not substantially related subjective well-being. The explanatory power of general Internet use or SNS use to p…
Internalizing problems as a mediator in the relationship between low effortful control and internet abuse in adolescence: A three-wave longitudinal s…
2019
Abstract The aim of the study is to examine the relationships between early adolescents' low effortful control, middle adolescents' internalizing problems and late adolescents' Internet abuse, focusing on the mediating role that middle adolescents' internalizing problems may play in the relationship between early adolescents' low effortful control and late adolescents' Internet abuse. The study followed a sample of 482 adolescents (245 boys and 237 girls) from early adolescence (wave 1; mean age = 14.76, SD = 0.63), through middle adolescence (wave 2; mean age = 15.77, SD = 0.61), to late adolescence (wave 3; mean age = 17.88, SD = 0.57). The participants completed self-report questionnaire…
Developmental dynamics between children’s externalizing problems, task-avoidant behavior, and academic performance in early school years: A 4-year fo…
2015
This longitudinal study investigated the associations among children’s externalizing problems, task-avoidant behavior, and academic performance in early school years. The participants were 586 children (43% girls, 57% boys). Data pertaining to externalizing problems (teacher ratings) and task-avoidant behaviors (mother and teacher ratings) were gathered, and the children were tested yearly on their academic performance in Grades 1–4. The results were similar for both genders. The analyses supported a mediation model: high externalizing problems in Grades 1 and 2 were linked with low academic performance in Grades 3 and 4 through increases in task-avoidant behavior in Grades 2 and 3. The res…
Influences on the Development of Economic Knowledge over the First Academic Year
2020
Despite significant research, it remains unclear whether the goal of developing domain-specific knowledge in higher education is actually being achieved. This is also true for the internationally most popular study domain of business and economics. In Germany, a test for measuring economic knowledge was validated, enabling the analysis of change in knowledge over the course of studies. Business and economics students from across Germany were surveyed over the course of one study year: 7,111 beginning students in the winter term of 2016/2017, and 1,705 third semester students in the winter term of 2017/2018. Investigating the longitudinal matched sample of 734 students who took part at both …
The COVID-19 Assessment for Survival at Admission (CASA) Index: A 12 Months Observational Study
2021
Objective: Coronavirus disease 2019 (COVID-19) is a disease with a high rate of progression to critical illness. However, the stratification of patients at risk of mortality is not well defined. In this study, we aimed to define a mortality risk index to allocate patients to the appropriate intensity of care.Methods: This is a 12 months observational longitudinal study designed to develop and validate a pragmatic mortality risk score to stratify COVID-19 patients aged ≥18 years and admitted to hospital between March 2020 and March 2021. Main outcome was in-hospital mortality.Results: 244 patients were included in the study (mortality rate 29.9%). The Covid-19 Assessment for Survival at Admi…