From severance pay to self-insurance: Effects of severance payments savings accounts in Colombia

In 1990 Colombia replaced its traditional system of severance paymentswith a new system of severance payments savings accounts (SPSAs). Althoughseverance payments often are justified on the grounds that they provideinsurance against earnings loss, they also increase costs for employersand distort employment decisions. The impact of severance payments dependslargely on how much of the costs to employers can be shifted to workers.The theoretical analysis in this paper shows that, in contrast to atraditional system of severance payments, the system of SPSAs facilitatesthe shifting of severance payments costs to workers in the form of lowerwages. Empirical results using the Colombian National Household Surveysindicate that the introduction of SPSAs shifted around 80% of the totalseverance payments contributions to wages and had a positive effect onweekly hours. Results using the 1997 Colombian Living Standards MeasurementSurvey suggest that, although SPSAs in part replaced employer insurancewith self-insurance, SPSAs continue to play a consumption smoothing rolefor the non-employed.

Self-interference of charge carriers in ferromagnetic SrRuO3

We report a systematic study of the low-temperature electrical conductivity in a series of SrRuO3 epitaxial thin films. At relatively high temperature the films display the conventional metallic behavior. However, a well-defined resistivity minimum appears at low temperature. This temperature dependence can be well described in a weak localization scenario: the resistivity minimum arising from the competition of electronic self-interference effects and the normal metallic character. By appropriate selection of the film growth conditions, we have been able to modify the mean-free path of itinerant carriers and thus to tune the relative strength of the quantum effects. We show that data can be quantitatively described by available theoretical models.

A well-posedness theory in measures for some kinetic models of collective motion

We present existence, uniqueness and continuous dependence results for some kinetic equations motivated by models for the collective behavior of large groups of individuals. Models of this kind have been recently proposed to study the behavior of large groups of animals, such as flocks of birds, swarms, or schools of fish. Our aim is to give a well-posedness theory for general models which possibly include a variety of effects: an interaction through a potential, such as a short-range repulsion and long-range attraction; a velocity-averaging effect where individuals try to adapt their own velocity to that of other individuals in their surroundings; and self-propulsion effects, which take into account effects on one individual that are independent of the others. We develop our theory in a space of measures, using mass transportation distances. As consequences of our theory we show also the convergence of particle systems to their corresponding kinetic equations, and the local-in-time convergence to the hydrodynamic limit for one of the models.

Effects of manipulating Task Complexity on self-repairs during L2 oral production

This paper analyses the effects of manipulating the cognitive complexity of L2 oral tasks on language production. It specifically focuses on self-repairs, which are taken as a measure of accuracy since they denote both attention to form and an attempt at being accurate. By means of a repeated measures de- sign, 42 lower-intermediate students were asked to perform three different tasks types (a narrative, and instruction-giving task, and a decision-making task) for which two degrees of cognitive complexity were established. The narrative task was manipulated along +/− Here-and-Now, an instruction-giving task ma- nipulated along +/− elements, and the decision-making task which is manipu- lated along +/− reasoning demands. Repeated measures ANOVAs are used for the calculation of differences between degrees of complexity and among task types. One-way ANOVA are used to detect potential differences between low- proficiency and high-proficiency participants. Results show an overall effect of Task Complexity on self-repairs behavior across task types, with different be- haviors existing among the three task types. No differences are found between the self-repair behavior between low and high proficiency groups. Results are discussed in the light of theories of cognition and L2 performance (Robin- son 2001a, 2001b, 2003, 2005, 2007), L1 and L2 language production models (Levelt 1989, 1993; Kormos 2000, 2006), and attention during L2 performance (Skehan 1998; Robinson, 2002).

School composition effects in Spain

Drawing on PISA data of 2006, this study examines the impact of socio-economic school composition on science test score achievement for Spanish students in compulsory secondary schools. We define school composition in terms of the average parental human capital of students in the same school. These contextual peer effects are estimated using a semi-parametric methodology, which enables the spillovers to affect all the parameters of the educational production function. We also deal with the potential problem of self-selection of student into schools, using an artificial sorting that we argue to be independent from unobserved student’s abilities. The results indicate that the association between socio-economic school composition and test score results is clearly positive and significantly higher when computed with the semi-parametric approach. However, we find that the endogenous sorting of students into schools plays a fundamental role, given that the spillovers are significantly reduced when this selection process is ruled out from our measure of school composition effects. Specifically, the estimations suggest that the contextual peer effects are moderately positive only in those schools where the socio-economic composition is considerably elevated. In addition, we find some evidence of asymmetry of how the external effects and the sorting process actually operate, which seem affect in a different way males and females as well as high and low performance students.

The effects of teacher talk on students’ oral productions

The present study is a brief personal enquiry into the teaching and learning of EFL in the classroom with an orientation to action and personal professional development. It focuses on teacher talk, making special emphasis on questions, as well as on students’ resulting oral productions. The research contains samples of empirical data, which include their interpretations in the light of relevant research literature, and a more personal overall reflection of the teaching practice. Both the analysis and the reflections derive to a large extent from the self-observation paper 1 (SO1) and the Practicum portfolio (PP) developed within the TED Masters Degree practicum stages

Determinants of the educational use of digital learning materials: The mediating role of self-efficacy, perceived norm and attitude

Initiatives to stimulate the development and propagation of open educational resources (OER) need a sufficiently large community that can be mobilized to participate in this endeavour. Failure to achieve this could lead to underuse of OER. In the context of the Wikiwijs initiative a large scale survey was undertaken amongst primary and secondary school teachers to explore possible determinants of the educational use of digital learning materials (DLMs). Basing on the Integrative Model of Behaviour Prediction it was conjectured that self-efficacy, attitude and perceived norm would take a central role in explaining the intention to use DLMs. Several other predictors were added to the model as well whose effects were hypothesized to be mediated by the three central variables.All conjectured relationships were found using path analysis on survey data from 1484 teachers. Intention to DLMs was most strongly determined by self-efficacy, followed by attitude. ICT proficiency was in its turn the strongest predictor of self-efficacy. Perceived norm played only a limited role in the intention to use DLMs. Concluding, it seems paramount for the success of projects such as Wikiwijs to train teachers in the use of digital learning materials and ICT (e.g. the digital blackboard) and to impact on their attitude.

The effects of walking while working on productivity and health: a field experiment

Lack of physical activity can cause health problems and diminish organizational productivity. We conducted a 12-months long field experiment in a financial services company to study the effects of slow-moving treadmills outfitted for office work on employee productivity and health. 43 sedentary volunteers were assigned randomly to two groups to receive treadmill workstations 7 months apart. Employees could opt at will for standard chair-desk arrangement. Biometric measurements were taken quarterly and weekly online performance surveys were administered to study participants and to more than 200 non-participants and their supervisors.In this study we explore three questions concerning the effects of the introduction of treadmills in the workplace. (1) Does it improve overall physical activity? (2) Does it improve health measures? (3) Does it improve performance? The answers are as follows. (1) Yes (net effect of almost half an hour a day). (2) Yes (small gains, one minor decline). (3) No and yes (initial decline followed by increase to recover to initial level within one year) – based on weekly employee self reports.

A longitudinal study of environmental tobacco smoke exposure in children: parental self reports versus age dependent biomarkers

Background: Awareness of the negative effects of smoking on children's health prompted a decrease in the self-reporting of parental tobacco use in periodic surveys from most industrialized countries. Our aim is to assess changes between ETS exposure at the end of pregnancy and at 4 years of age determined by the parents' self-report and measurement of cotinine in age related biological matrices.Methods: The prospective birth cohort included 487 infants from Barcelona city (Spain). Mothers were asked about maternal and household smoking habit. Cord serum and children's urinary cotinine were analyzed in duplicate using a double antibody radioimmunoassay. Results: At 4 years of age, the median urinary cotinine level in children increased 1.4 or 3.5 times when father or mother smoked, respectively. Cotinine levels in children's urine statistically differentiated children from smoking mothers (Geometric Mean (GM) 19.7 ng/ml; 95% CI 16.83–23.01) and exposed homes (GM 7.1 ng/ml; 95% CI 5.61–8.99) compared with non-exposed homes (GM 4.5 ng/ml; 95% CI 3.71–5.48). Maternal self-reported ETS exposure in homes declined in the four year span between the two time periods from 42.2% to 31.0% (p < 0.01). Nevertheless, most of the children considered non-exposed by their mothers had detectable levels of cotinine above 1 ng/mL in their urine.Conclusion: We concluded that cotinine levels determined in cord blood and urine, respectively, were useful for categorizing the children exposed to smoking and showed that a certain increase in ETS exposure during the 4-year follow-up period occurred.

8-month non-use of a language. A case tudy. A longitudinal study of the effects on non use of one of the languages (Spanish) of a German L1 multilingual

Under the Dynamic Model of Multilingualism multilinguals are especially vulnerable to language attrition. It was the aim of the present study to verify if this was the case and to observe whether the different linguistic skills (receptive vs. descriptive) and the different linguistic levels (syntactic, lexical, morphological, etc.) would be affected equally.Data were gathered longitudinally by means of a language test for the subject’s reading, writing, listening and speaking skills as well as her knowledge of grammar and vocabulary. Although the overall accuracy remained intact and no proof for attrition in the receptive skills was found, the productive skills - mainly fluency - were shown to have suffered from language attrition. This was demonstrated by an increase in the number of pauses, hesitations, repetitions and self-corrections among others and decrease in the percentage of error-free clauses and decrease in the clause length, in oral and written fluency respectively.

The effects of electron-hole separation on the photoconductivity of individual metal oxide nanowires

The responses of individual ZnO nanowires to UV light demonstrate that the persistent photoconductivity (PPC) state is directly related to the electron¿hole separation near the surface. Our results demonstrate that the electrical transport in these nanomaterials is influenced by the surface in two different ways. On the one hand, the effective mobility and the density of free carriers are determined by recombination mechanisms assisted by the oxidizing molecules in air. This phenomenon can also be blocked by surface passivation. On the other hand, the surface built-in potential separates the photogenerated electron¿hole pairs and accumulates holes at the surface. After illumination, the charge separation makes the electron¿hole recombination difficult and originates PPC. This effect is quickly reverted after increasing either the probing current (self-heating by Joule dissipation) or the oxygen content in air (favouring the surface recombination mechanisms). The model for PPC in individual nanowires presented here illustrates the intrinsic potential of metal oxide nanowires to develop optoelectronic devices or optochemical sensors with better and new performances.

Generational effects on adult height in individual heterogeneity

As adult height is a well-established retrospective measure of health and standard of living, it is important to understand the factors that determine it. Among them, the influence of socio-environmental factors has been subjected to empirical scrutiny. This paper explores the influence of generational (or environmental) effects and individual and gender-specific heterogeneity on adult height. Our data set is from contemporary Spain, a country governed by an authoritarian regime between 1939 and 1977. First, we use normal position and quantile regression analysis to identify the determinants of self-reported adult height and to measure the influence of individual heterogeneity. Second, we use a Blinder-Oaxaca decomposition approach to explain the `gender height gap¿ and its distribution, so as to measure the influence on this gap of individual heterogeneity. Our findings suggest a significant increase in adult height in the generations that benefited from the country¿s economic liberalization in the 1950s, and especially those brought up after the transition to democracy in the 1970s. In contrast, distributional effects on height suggest that only in recent generations has ¿height increased more among the tallest¿. Although the mean gender height gap is 11 cm, generational effects and other controls such as individual capabilities explain on average roughly 5% of this difference, a figure that rises to 10% in the lowest 10% quantile.

Self-organizing propagation patterns from dynamic self-assembly in monolayers

Propagation of localized orientational waves, as imaged by Brewster angle microscopy, is induced by low intensity linearly polarized light inside axisymmetric smectic-C confined domains in a photosensitive molecular thin film at the air/water interface (Langmuir monolayer). Results from numerical simulations of a model that couples photoreorientational effects and long-range elastic forces are presented. Differences are stressed between our scenario and the paradigmatic wave phenomena in excitable chemical media.

Self-organizing propagation patterns from dynamic self-assembly in monolayers

Propagation of localized orientational waves, as imaged by Brewster angle microscopy, is induced by low intensity linearly polarized light inside axisymmetric smectic-C confined domains in a photosensitive molecular thin film at the air/water interface (Langmuir monolayer). Results from numerical simulations of a model that couples photoreorientational effects and long-range elastic forces are presented. Differences are stressed between our scenario and the paradigmatic wave phenomena in excitable chemical media.

Generational effects on adult height in individual heterogeneity

As adult height is a well-established retrospective measure of health and standard of living, it is important to understand the factors that determine it. Among them, the influence of socio-environmental factors has been subjected to empirical scrutiny. This paper explores the influence of generational (or environmental) effects and individual and gender-specific heterogeneity on adult height. Our data set is from contemporary Spain, a country governed by an authoritarian regime between 1939 and 1977. First, we use normal position and quantile regression analysis to identify the determinants of self-reported adult height and to measure the influence of individual heterogeneity. Second, we use a Blinder-Oaxaca decomposition approach to explain the `gender height gap¿ and its distribution, so as to measure the influence on this gap of individual heterogeneity. Our findings suggest a significant increase in adult height in the generations that benefited from the country¿s economic liberalization in the 1950s, and especially those brought up after the transition to democracy in the 1970s. In contrast, distributional effects on height suggest that only in recent generations has ¿height increased more among the tallest¿. Although the mean gender height gap is 11 cm, generational effects and other controls such as individual capabilities explain on average roughly 5% of this difference, a figure that rises to 10% in the lowest 10% quantile.