Transverse galloping of two-dimensional bodies having a rhombic cross-section

Transverse galloping is a type of aeroelastic instability characterized by oscillations perpendicular to wind direction, large amplitude and low frequency, which appears in some elastic two-dimensional bluff bodies when they are subjected to an incident flow, provided that the flow velocity exceeds a threshold critical value. Understanding the galloping phenomenon of different cross-sectional geometries is important in a number of engineering applications: for energy harvesting applications the interest relies on strongly unstable configurations but in other cases the purpose is to avoid this type of aeroelastic phenomenon. In this paper the aim is to analyze the transverse galloping behavior of rhombic bodies to understand, on the one hand, the dependence of the instability with a geometrical parameter such as the relative thickness and, on the other hand, why this cross-section shape, that is generally unstable, shows a small range of relative thickness values where it is stable. Particularly, the non-galloping rhombus-shaped prism?s behavior is revised through wind tunnel experiments. The bodies are allowed to freely move perpendicularly to the incoming flow and the amplitude of movement and pressure distributions on the surfaces is measured.

Antecedents and consequences of percieved effective managerial coaching:an individual, team-level and cross-level examination

The major contribution of the study is the identification of a positive link between perceived effective managerial coaching (PEMC) and team task performance and also, the examination of PEMC adopting a multilevel research design and incorporating dual-source data. Specifically, drawing on social psychology, the thesis aims at developing and testing a comprehensive conceptual framework of the antecedents and consequences of PEMC for knowledge workers. The model takes into consideration intrapersonal, interpersonal and team-level characteristics, which relate to PEMC and, subsequently associate with important work outcomes. In this regard, the thesis identifies PEMC as a practice of dual nature in that it may be experienced not only as a one-on-one workplace developmental interaction, but also as a managerial practice that is experienced by each member of a team for co-ordination purposes. Adopting a cross-sectional survey research design, the hypotheses are tested in three organisations in Greece and the UK. In particular, hierarchical linear modelling of 191 employees nested in 60 teams yields that employees’ learning goal orientation (LGO) and high-quality exchanges between an employee and a manager (LMX) are positively related to effective MC, while a manager’s LGO moderates the relationship between employees’ LGO and PEMC. In turn, PEMC, as a one-on-one practice, is related to cognitive outcomes, such as information sharing, while as a shared team practice is related also to behavioural outcomes, including individual and team performance. Overall, the study contributes to a growing body of coaching and management literature that acknowledges PEMC as a core managerial practice.

Cross-section and panel estimates of peer effects in early adolescent cannabis use: With a little help from my ‘friends once removed’

Peer effects in adolescent cannabis are difficult to estimate, due in part to the lack of appropriate data on behaviour and social ties. This paper exploits survey data that have many desirable properties and have not previously been used for this purpose. The data set, collected from teenagers in three annual waves from 2002-2004 contains longitudinal information about friendship networks within schools (N = 5,020). We exploit these data on network structure to estimate peer effects on adolescents from their nominated friends within school using two alternative approaches to identification. First, we present a cross-sectional instrumental variable (IV) estimate of peer effects that exploits network structure at the second degree, i.e. using information on friends of friends who are not themselves ego’s friends to instrument for the cannabis use of friends. Second, we present an individual fixed effects estimate of peer effects using the full longitudinal structure of the data. Both innovations allow a greater degree of control for correlated effects than is commonly the case in the substance-use peer effects literature, improving our chances of obtaining estimates of peer effects than can be plausibly interpreted as causal. Both estimates suggest positive peer effects of non-trivial magnitude, although the IV estimate is imprecise. Furthermore, when we specify identical models with behaviour and characteristics of randomly selected school peers in place of friends’, we find effectively zero effect from these ‘placebo’ peers, lending credence to our main estimates. We conclude that cross-sectional data can be used to estimate plausible positive peer effects on cannabis use where network structure information is available and appropriately exploited.

Knowledge about sources of dietary fibres and health effects using a validated scale: a cross-country study

Objectives Dietary fibre (DF) is one of the components of diet that strongly contributes to health improvements, particularly on the gastrointestinal system. Hence, this work intended to evaluate the relations between some sociodemographic variables such as age, gender, level of education, living environment or country on the levels of knowledge about dietary fibre (KADF), its sources and its effects on human health, using a validated scale. Study design The present study was a cross-sectional study. Methods A methodological study was conducted with 6010 participants, residing in 10 countries from different continents (Europe, America, Africa). The instrument was a questionnaire of self-response, aimed at collecting information on knowledge about food fibres. The instrument was used to validate a scale (KADF) which model was used in the present work to identify the best predictors of knowledge. The statistical tools used were as follows: basic descriptive statistics, decision trees, inferential analysis (t-test for independent samples with Levene test and one-way ANOVA with multiple comparisons post hoc tests). Results The results showed that the best predictor for the three types of knowledge evaluated (about DF, about its sources and about its effects on human health) was always the country, meaning that the social, cultural and/or political conditions greatly determine the level of knowledge. On the other hand, the tests also showed that statistically significant differences were encountered regarding the three types of knowledge for all sociodemographic variables evaluated: age, gender, level of education, living environment and country. Conclusions The results showed that to improve the level of knowledge the actions planned should not be delineated in general as to reach all sectors of the populations, and that in addressing different people, different methodologies must be designed so as to provide an effective health education.

Sources of Information about Dietary Fibre: A Cross-Country Survey

Problem statement: Dietary fibre (DF) has been recognized as a major determinant for improvement of health. Hence the means of information through which people become aware of its benefits are crucial. Research questions: Where do you usually find information about dietary fibre? What means of communication do you consider the most appropriate to encourage the consumption of dietary fibre? Purpose of the study: This work aimed at studying the sources of information about dietary fibre, as a means to educate people about aspects related to healthy eating. Factors such as gender, level of education, living environment or country were evaluated as to their effect on the selection of sources and preferences.   Research Methods: Descriptive cross-sectional study by means of a questionnaire, applied to a non-probabilistic sample of 6010 participants from 10 countries in different continents (Europe, Africa and America), answered after informed consent by all participants. For the analysis were used several descriptive statistics tools, crosstabs and chi square test to assess the relations between some of the variables under study. Findings: Mostly the information about DF comes from the internet, but television is recognized as suitable. Differences were found between genders, levels of education, living environments and countries. The internet (preferred source), got highest scores for Hungary, urban areas, university education and female gender. The radio (least scored source) was preferred in Egypt, for men and with lower education (primary school). Conclusions: People get information through the internet due to easy access. However, it is to some extent a risk given the impossibility to control de information made public on the internet. The role of health centres and hospitals as well as schools should definitely be increased, as a responsible way to ensure correct information.

Sources of Information about Dietary Fibre: A Cross-Country Survey

Dietary fibre (DF) has been recognized as a major determinant for improvement of health. Hence the means of information through which people become aware of its benefits are crucial. This work aimed at studying the sources of information about DF, as a means to educate people about aspects related to healthy eating. Factors such as gender, level of education, living environment or country were evaluated as to their effect on the selection of sources and preferences. For this, a descriptive cross-sectional study by means of a questionnaire, applied to a non-probabilistic sample of 6010 participants from 10 countries in different continents (Europe, Africa and America), answered after informed consent by all participants. For the analysis were used several descriptive statistics tools, crosstabs and chi square test to assess the relations between some of the variables under study. The results showed that mostly the information about DF comes from the internet, but the participants recognize that television might be a most suitable way to disseminate information about DF. The results also indicated differences between genders, levels of education, living environments and countries. The internet, the preferred source of information, got highest scores for Hungary, for urban areas, for university level of education and for female gender. The radio, the least scored source of information, was preferred in Egypt, for men and with lower education (primary school). As a conclusion, people get information through the internet due to easy access. However, it is to some extent a risk given the impossibility to control de information made public on the internet. The role of health centers and hospitals as well as schools should definitely be increased, as a responsible way to ensure correct information.