Reciprocity as a trigger of social cooperation in contemporary immigration societies?

While the system stabilizing function of reciprocity is widely acknowledged, much less attention has been paid to the argument that reciprocity might initiate social cooperation in the first place. This paper tests Gouldner’s early assumption that reciprocity may act as a ‘starting mechanism’ of social cooperation in consolidating societies. The empirical test scenario builds on unequal civic engagement between immigrants and nationals, as this engagement gap can be read as a lack of social cooperation in consolidating immigration societies. Empirical analyses using survey data on reciprocal norms and based on Bayesian hierarchical modelling lend support for Gouldner’s thesis, underlining thereby the relevance of reciprocity in today’s increasingly diverse societies: individual norms of altruistic reciprocity elevate immigrants’ propensity to volunteer, reducing thereby the engagement gap between immigrants and natives in the area of informal volunteering. In other words, compliance with altruistic reciprocity may trigger cooperation in social strata, where it is less likely to occur. The positive moderation of the informal engagement gap through altruistic reciprocity turns out to be most pronounced for immigrants who are least likely to engage in informal volunteering, meaning low, but also high educated immigrants.

Self-assembly into nanoparticles is essential for receptor mediated uptake of therapeutic antisense oligonucleotides

Antisense oligonucleotides (ASOs) have the potential of revolutionizing medicine due to their ability to manipulate gene function for therapeutic purposes. ASOs are chemically modified and/or incorporated with nanoparticles to enhance their stability and cellular uptake; however, one of the biggest challenges is the poor understanding of their uptake mechanism, which is needed for designing better ASOs with high activity and low toxicity. Here, we study the uptake mechanism of three therapeutically relevant ASOs (peptide-conjugated phosphorodiamidate morpholino (P-PMO), 2?Omethyl phosphorothioate (2?OMe) and phosphorothioated tricyclo DNA (tcDNA) that have been optimized to induce exon skipping in models of Deuchenne muscular dystrophy (DMD). We show that P-PMO and tcDNA have high propensity to spontaneously self-assemble into nanoparticles. P-PMO forms micelles of defined size and their net charge (zeta potential) is dependent on the medium and concentration. In biomimetic conditions and at low concentrations P-PMO obtains net negative charge and its uptake is mediated by class A scavenger receptor subtypes (SCARAs) as shown by competitive inhibition and RNAi silencing experiments in-vitro. In-vivo, the activity of P-PMO was significantly decreased in SCARA1 knock-out mice compared to wild-type animals. Additionally, we show that SCARA1 is involved in the uptake of tcDNA and 2?OMe as shown by competitive inhibition and co-localization experiments. Surface plasmon resonance binding analysis to SCARA1 demonstrated that P-PMO and tcDNA have higher binding profiles to the receptor compared to 2?OMe. These results demonstrate receptor-mediated uptake for a range of ASO chemistries, a mechanism that is dependent on their self-assembly into nanoparticles.

Pre-Election Positions and Voting Behaviour in Parliament: Consistency among Swiss MPs

This article examines the determinants of positional incongruence between pre-election statements and post-election behaviour in the Swiss parliament between 2003 and 2009. The question is examined at the individual MP level, which is appropriate for dispersion-of-powers systems like Switzerland. While the overall rate of political congruence reaches about 85%, a multilevel logit analysis detects the underlying factors which push or curb a candidate's propensity to change his or her mind once elected. The results show that positional changes are more likely when (1) MPs are freshmen, (2) individual voting behaviour is invisible to the public, (3) the electoral district magnitude is not small, (4) the vote is not about a party's core issue, (5) the MP belongs to a party which is located in the political centre, and (6) if the pre-election statement dissents from the majority position of the legislative party group. Of these factors, the last one is paramount.

Direct Democracy and Institutional Trust: Relationships and Differences across Personality Traits

Direct democracy plays a prominent role in the explanation of institutional trust. To date, however, empirical findings on the effects of direct democracy remain inconclusive. In this article, we argue that this inconclusiveness can be partly ascribed to the diverse effects direct democracy has on individuals. In other words, direct democracy influences institutional trust, but how and to what degree depends on individuals’ personality traits. Running hierarchical analyses of unique survey data from a random sample of eligible Swiss voters, we document three findings: First, we show that the number of ballot measures is not directly associated with institutional trust. Second, we demonstrate that the Big Five personality traits affect the propensity to trust. Third, some of these traits also alter the relationship between direct democracy and institutional trust, suggesting that certain personality types are more likely to be sensitive to popular votes than others and that not everyone is equally likely to respond to political stimuli, even in highly democratic environments.

Uso de las tierras, fisiografía y degradación, en el noreste del departamento Aluminé, Neuquén

La cuenca del río Kilca es uno de los principales sistemas hidrográficos de la región antecordillerana, ubicada en el centro de la provincia de Neuquén. En esta zona, de clima subhúmedo, el uso de suelo dominante es el de "veranada", que consiste en una de las tres etapas anuales de un tipo de ganadería trashumante, basado en el aprovechamiento forrajero de pastizales naturales. Dada la constitución fisiográfica de estos paisajes, existe en ellos una gran propensión al desarrollo de procesos geomorfológicos de erosión y remoción en masa. Los factores históricos vinculados a la evolución de la actividad ganadera en la región a ambos lados del eje cordillerano, han determinado desde fines del siglo XIX, modalidades de uso de suelo caracterizadas por el exceso estacional de la carga ganadera. Esta organización de la actividad implicó, no sólo un deterioro de las pasturas, sino además el desencadenamiento y aceleración de los procesos geomorfológicos. El objetivo de este trabajo es analizar la problemática actual, enfocando los procesos del medio biofísico, vinculados con las prácticas sociales. En este sentido, se describen y explican las condiciones fisiográficas, en términos del grado de inestabilidad y deterioro de las tierras.

Uso de las tierras, fisiografía y degradación, en el noreste del departamento Aluminé, Neuquén

La cuenca del río Kilca es uno de los principales sistemas hidrográficos de la región antecordillerana, ubicada en el centro de la provincia de Neuquén. En esta zona, de clima subhúmedo, el uso de suelo dominante es el de "veranada", que consiste en una de las tres etapas anuales de un tipo de ganadería trashumante, basado en el aprovechamiento forrajero de pastizales naturales. Dada la constitución fisiográfica de estos paisajes, existe en ellos una gran propensión al desarrollo de procesos geomorfológicos de erosión y remoción en masa. Los factores históricos vinculados a la evolución de la actividad ganadera en la región a ambos lados del eje cordillerano, han determinado desde fines del siglo XIX, modalidades de uso de suelo caracterizadas por el exceso estacional de la carga ganadera. Esta organización de la actividad implicó, no sólo un deterioro de las pasturas, sino además el desencadenamiento y aceleración de los procesos geomorfológicos. El objetivo de este trabajo es analizar la problemática actual, enfocando los procesos del medio biofísico, vinculados con las prácticas sociales. En este sentido, se describen y explican las condiciones fisiográficas, en términos del grado de inestabilidad y deterioro de las tierras.

Uso de las tierras, fisiografía y degradación, en el noreste del departamento Aluminé, Neuquén

La cuenca del río Kilca es uno de los principales sistemas hidrográficos de la región antecordillerana, ubicada en el centro de la provincia de Neuquén. En esta zona, de clima subhúmedo, el uso de suelo dominante es el de "veranada", que consiste en una de las tres etapas anuales de un tipo de ganadería trashumante, basado en el aprovechamiento forrajero de pastizales naturales. Dada la constitución fisiográfica de estos paisajes, existe en ellos una gran propensión al desarrollo de procesos geomorfológicos de erosión y remoción en masa. Los factores históricos vinculados a la evolución de la actividad ganadera en la región a ambos lados del eje cordillerano, han determinado desde fines del siglo XIX, modalidades de uso de suelo caracterizadas por el exceso estacional de la carga ganadera. Esta organización de la actividad implicó, no sólo un deterioro de las pasturas, sino además el desencadenamiento y aceleración de los procesos geomorfológicos. El objetivo de este trabajo es analizar la problemática actual, enfocando los procesos del medio biofísico, vinculados con las prácticas sociales. En este sentido, se describen y explican las condiciones fisiográficas, en términos del grado de inestabilidad y deterioro de las tierras.

Caste, land, and migration : a preliminary analysis of a village survey in an underdeveloped state in India

This paper explores migration from Bihar, one of the most underdeveloped states in India, by paying particular attention to social class (caste) and landholdings. After describing details of individual migrants, we present our preliminary findings on the determinants of migration, based on our field survey of 200 households in four villages in 2011. In terms of social class, Muslims are more likely to migrate, but Scheduled Castes do not show a high propensity to migrate as is stated in some of the existing literature where the underclass is said to be more mobile. In terms of landholdings, the probability that someone will migrate is high among the landless and smaller landholders but it decreases as the size of the landholding increases. However, as the size of the landholding increases still further, a reverse effect of landholding on decisions regarding migration moves in, with the decline in probability becoming less and less. This result confirms a non-linear relationship between landholdings and the decision to migrate. Some further research questions are raised in the paper.

Modelling the Impact of Built Environment, Geographical Scales and Latent Constructs On Individual Travel Behaviour

La relación entre la estructura urbana y la movilidad ha sido estudiada desde hace más de 70 años. El entorno urbano incluye múltiples dimensiones como por ejemplo: la estructura urbana, los usos de suelo, la distribución de instalaciones diversas (comercios, escuelas y zonas de restauración, parking, etc.). Al realizar una revisión de la literatura existente en este contexto, se encuentran distintos análisis, metodologías, escalas geográficas y dimensiones, tanto de la movilidad como de la estructura urbana. En este sentido, se trata de una relación muy estudiada pero muy compleja, sobre la que no existe hasta el momento un consenso sobre qué dimensión del entorno urbano influye sobre qué dimensión de la movilidad, y cuál es la manera apropiada de representar esta relación. Con el propósito de contestar estas preguntas investigación, la presente tesis tiene los siguientes objetivos generales: (1) Contribuir al mejor entendimiento de la compleja relación estructura urbana y movilidad. y (2) Entender el rol de los atributos latentes en la relación entorno urbano y movilidad. El objetivo específico de la tesis es analizar la influencia del entorno urbano sobre dos dimensiones de la movilidad: número de viajes y tipo de tour. Vista la complejidad de la relación entorno urbano y movilidad, se pretende contribuir al mejor entendimiento de la relación a través de la utilización de 3 escalas geográficas de las variables y del análisis de la influencia de efectos inobservados en la movilidad. Para el análisis se utiliza una base de datos conformada por tres tipos de datos: (1) Una encuesta de movilidad realizada durante los años 2006 y 2007. Se obtuvo un total de 943 encuestas, en 3 barrios de Madrid: Chamberí, Pozuelo y Algete. (2) Información municipal del Instituto Nacional de Estadística: dicha información se encuentra enlazada con los orígenes y destinos de los viajes recogidos en la encuesta. Y (3) Información georeferenciada en Arc-GIS de los hogares participantes en la encuesta: la base de datos contiene información respecto a la estructura de las calles, localización de escuelas, parking, centros médicos y lugares de restauración. Se analizó la correlación entre e intra-grupos y se modelizaron 4 casos de atributos bajo la estructura ordinal logit. Posteriormente se evalúa la auto-selección a través de la estimación conjunta de las elecciones de tipo de barrio y número de viajes. La elección del tipo de barrio consta de 3 alternativas: CBD, Urban y Suburban, según la zona de residencia recogida en las encuestas. Mientras que la elección del número de viajes consta de 4 categorías ordinales: 0 viajes, 1-2 viajes, 3-4 viajes y 5 o más viajes. A partir de la mejor especificación del modelo ordinal logit. Se desarrolló un modelo joint mixed-ordinal conjunto. Los resultados indican que las variables exógenas requieren un análisis exhaustivo de correlaciones con el fin de evitar resultados sesgados. ha determinado que es importante medir los atributos del BE donde se realiza el viaje, pero también la información municipal es muy explicativa de la movilidad individual. Por tanto, la percepción de las zonas de destino a nivel municipal es considerada importante. En el contexto de la Auto-selección (self-selection) es importante modelizar conjuntamente las decisiones. La Auto-selección existe, puesto que los parámetros estimados conjuntamente son significativos. Sin embargo, sólo ciertos atributos del entorno urbano son igualmente importantes sobre la elección de la zona de residencia y frecuencia de viajes. Para analizar la Propensión al Viaje, se desarrolló un modelo híbrido, formado por: una variable latente, un indicador y un modelo de elección discreta. La variable latente se denomina “Propensión al Viaje”, cuyo indicador en ecuación de medida es el número de viajes; la elección discreta es el tipo de tour. El modelo de elección consiste en 5 alternativas, según la jerarquía de actividades establecida en la tesis: HOME, no realiza viajes durante el día de estudio, HWH tour cuya actividad principal es el trabajo o estudios, y no se realizan paradas intermedias; HWHs tour si el individuo reaiza paradas intermedias; HOH tour cuya actividad principal es distinta a trabajo y estudios, y no se realizan paradas intermedias; HOHs donde se realizan paradas intermedias. Para llegar a la mejor especificación del modelo, se realizó un trabajo importante considerando diferentes estructuras de modelos y tres tipos de estimaciones. De tal manera, se obtuvieron parámetros consistentes y eficientes. Los resultados muestran que la modelización de los tours, representa una ventaja sobre la modelización de los viajes, puesto que supera las limitaciones de espacio y tiempo, enlazando los viajes realizados por la misma persona en el día de estudio. La propensión al viaje (PT) existe y es específica para cada tipo de tour. Los parámetros estimados en el modelo híbrido resultaron significativos y distintos para cada alternativa de tipo de tour. Por último, en la tesis se verifica que los modelos híbridos representan una mejora sobre los modelos tradicionales de elección discreta, dando como resultado parámetros consistentes y más robustos. En cuanto a políticas de transporte, se ha demostrado que los atributos del entorno urbano son más importantes que los LOS (Level of Service) en la generación de tours multi-etapas. la presente tesis representa el primer análisis empírico de la relación entre los tipos de tours y la propensión al viaje. El concepto Propensity to Travel ha sido desarrollado exclusivamente para la tesis. Igualmente, el desarrollo de un modelo conjunto RC-Number of trips basado en tres escalas de medida representa innovación en cuanto a la comparación de las escalas geográficas, que no había sido hecha en la modelización de la self-selection. The relationship between built environment (BE) and travel behaviour (TB) has been studied in a number of cases, using several methods - aggregate and disaggregate approaches - and different focuses – trip frequency, automobile use, and vehicle miles travelled and so on. Definitely, travel is generated by the need to undertake activities and obtain services, and there is a general consensus that urban components affect TB. However researches are still needed to better understand which components of the travel behaviour are affected most and by which of the urban components. In order to fill the gap in the research, the present dissertation faced two main objectives: (1) To contribute to the better understanding of the relationship between travel demand and urban environment. And (2) To develop an econometric model for estimating travel demand with urban environment attributes. With this purpose, the present thesis faced an exhaustive research and computation of land-use variables in order to find the best representation of BE for modelling trip frequency. In particular two empirical analyses are carried out: 1. Estimation of three dimensions of travel demand using dimensions of urban environment. We compare different travel dimensions and geographical scales, and we measure self-selection contribution following the joint models. 2. Develop a hybrid model, integrated latent variable and discrete choice model. The implementation of hybrid models is new in the analysis of land-use and travel behaviour. BE and TB explicitly interact and allow richness information about a specific individual decision process For all empirical analysis is used a data-base from a survey conducted in 2006 and 2007 in Madrid. Spatial attributes describing neighbourhood environment are derived from different data sources: National Institute of Statistics-INE (Administrative: municipality and district) and GIS (circular units). INE provides raw data for such spatial units as: municipality and district. The construction of census units is trivial as the census bureau provides tables that readily define districts and municipalities. The construction of circular units requires us to determine the radius and associate the spatial information to our households. The first empirical part analyzes trip frequency by applying an ordered logit model. In this part is studied the effect of socio-economic, transport and land use characteristics on two travel dimensions: trip frequency and type of tour. In particular the land use is defined in terms of type of neighbourhoods and types of dwellers. Three neighbourhood representations are explored, and described three for constructing neighbourhood attributes. In particular administrative units are examined to represent neighbourhood and circular – unit representation. Ordered logit models are applied, while ordinal logit models are well-known, an intensive work for constructing a spatial attributes was carried out. On the other hand, the second empirical analysis consists of the development of an innovative econometric model that considers a latent variable called “propensity to travel”, and choice model is the choice of type of tour. The first two specifications of ordinal models help to estimate this latent variable. The latent variable is unobserved but the manifestation is called “indicators”, then the probability of choosing an alternative of tour is conditional to the probability of latent variable and type of tour. Since latent variable is unknown we fit the integral over its distribution. Four “sets of best variables” are specified, following the specification obtained from the correlation analysis. The results evidence that the relative importance of SE variables versus BE variables depends on how BE variables are measured. We found that each of these three spatial scales has its intangible qualities and drawbacks. Spatial scales play an important role on predicting travel demand due to the variability in measures at trip origin/destinations within the same administrative unit (municipality, district and so on). Larger units will produce less variation in data; but it does not affect certain variables, such as public transport supply, that are more significant at municipality level. By contrast, land-use measures are more efficient at district level. Self-selection in this context, is weak. Thus, the influence of BE attributes is true. The results of the hybrid model show that unobserved factors affect the choice of tour complexity. The latent variable used in this model is propensity to travel that is explained by socioeconomic aspects and neighbourhood attributes. The results show that neighbourhood attributes have indeed a significant impact on the choice of the type of tours either directly and through the propensity to travel. The propensity to travel has a different impact depending on the structure of each tour and increases the probability of choosing more complex tours, such as tours with many intermediate stops. The integration of choice and latent variable model shows that omitting important perception and attitudes leads to inconsistent estimates. The results also indicate that goodness of fit improves by adding the latent variable in both sequential and simultaneous estimation. There are significant differences in the sensitivity to the latent variable across alternatives. In general, as expected, the hybrid models show a major improvement into the goodness of fit of the model, compared to a classical discrete choice model that does not incorporate latent effects. The integrated model leads to a more detailed analysis of the behavioural process. Summarizing, the effect that built environment characteristics on trip frequency studied is deeply analyzed. In particular we tried to better understand how land use characteristics can be defined and measured and which of these measures do have really an impact on trip frequency. We also tried to test the superiority of HCM on this field. We can concluded that HCM shows a major improvement into the goodness of fit of the model, compared to classical discrete choice model that does not incorporate latent effects. And consequently, the application of HCM shows the importance of LV on the decision of tour complexity. People are more elastic to built environment attributes than level of services. Thus, policy implications must take place to develop more mixed areas, work-places in combination with commercial retails.

Comportamiento del paciente de la clínica dental. Modelo basado en la percepción de la calidad del servicio y fidelización del paciente

Esta tesis doctoral propone un modelo de comportamiento del paciente de la clínica dental, basado en la percepción de la calidad del servicio (SERVQUAL), la fidelización del paciente, acciones de Marketing Relacional y aspectos socioeconómicos relevantes, de los pacientes de clínicas dentales. En particular, el estudio de campo se lleva a cabo en el ámbito geográfico de la Comunidad de Madrid, España, durante los años 2012 y 2013. La primera parte del proceso de elaboración del modelo está basada en la recolección de datos. Para ello, se realizaron cinco entrevistas a expertos dentistas y se aplicaron dos tipos encuestas diferentes: una para el universo formado por el conjunto de los pacientes de las clínicas dentales y la otra para el universo formado el conjunto de los dentistas de las clínicas dentales de la Comunidad de Madrid. Se obtuvo muestras de: 200 encuestas de pacientes y 220 encuestas de dentistas activos colegiados en el Ilustre Colegio Oficial de Odontólogos y Estomatólogos de la I Región Madrid. En la segunda parte de la elaboración del modelo, se realizó el análisis de los datos, la inducción y síntesis del modelo propuesto. Se utilizó la metodología de modelos gráficos probabilísticos, específicamente, una Red Bayesiana, donde se integraron variables (nodos) y sus dependencias estadísticas causales (arcos dirigidos), que representan el conocimiento obtenido de los datos recopilados en las encuestas y el conocimiento derivado de investigaciones precedentes en el área. Se obtuvo una Red Bayesiana compuesta por 6 nodos principales, de los cuales dos de ellos son nodos de observación directa: “Revisit Intention” y “SERVQUAL”, y los otros cuatro nodos restantes son submodelos (agrupaciones de variables), estos son respectivamente: “Attitudinal”, “Disease Information”, “Socioeconomical” y “Services”. Entre las conclusiones principales derivadas del uso del modelo, como herramientas de inferencia y los análisis de las entrevistas realizadas se obtiene que: (i) las variables del nodo “Attitudinal” (submodelo), son las más sensibles y significativas. Al realizarse imputaciones particulares en las variables que conforman el nodo “Attitudinal” (“RelationalMk”, “Satisfaction”, “Recommendation” y “Friendship”) se obtienen altas probabilidades a posteriori en la fidelidad del paciente de la clínica dental, medida por su intención de revisita. (ii) En el nodo “Disease Information” (submodelo) se destaca la relación de dependencia causal cuando se imputa la variable “Perception of disease” en “SERVQUAL”, demostrando que la percepción de la gravedad del paciente condiciona significativamente la percepción de la calidad del servicio del paciente. Como ejemplo destacado, si se realiza una imputación en la variable “Clinic_Type” se obtienen altas probabilidades a posteriori de las variables “SERVQUAL” y “Revisit Intention”, lo que evidencia, que el tipo de clínica dental influye significativamente en la percepción de la calidad del servicio y en la fidelidad del paciente (intención de revisita). (iii) En el nodo “Socioeconomical” (submodelo) la variable “Sex” resultó no ser significativa cuando se le imputaban diferentes valores, por el contrario, la variable “Age” e “Income” mostraban altas variabilidades en las probabilidades a posteriori cuando se imputaba alguna variable del submodelo “Services”, lo que evidencia, que estas variables condicionan la intención de contratar servicios (“Services”), sobretodo en las franjas de edad de 30 a 51 años en pacientes con ingresos entre 3000€ y 4000€. (iv) En el nodo “Services” (submodelo) los pacientes de las clínicas dentales mostraron altas probabilidades a priori para contratar servicios de fisiotrapia oral y gingival: “Dental Health Education” y “Parking”. (v) Las variables de fidelidad del paciente medidas desde su perspectiva comportamental que fueron utilizadas en el modelo: “Visit/year” “Time_clinic”, no aportaron información significativa. Tampoco, la variable de fidelidad del cliente (actitudinal): “Churn Efford”. (vi) De las entrevistas realizadas a expertos dentistas se obtiene que, los propietarios de la clínica tradicional tienen poca disposición a implementar nuevas estrategias comerciales, debido a la falta de formación en la gestión comercial y por falta de recursos y herramientas. Existe un rechazo generalizado hacia los nuevos modelos de negocios de clínicas dentales, especialmente en las franquicias y en lo que a políticas comerciales se refiere. Esto evidencia una carencia de gerencia empresarial en el sector. Como líneas futuras de investigación, se propone profundizar en algunas relaciones de dependencia (causales) como SERVQUALServices; SatisfactionServices; RelationalMKServices, Perception of diseaseSatisfaction, entre otras. Así como, otras variables de medición de la fidelidad comportamental que contribuyan a la mejora del modelo, como por ej. Gasto del paciente y rentabilidad de la visita. ABSTRACT This doctoral dissertation proposes a model of the behavior of the dental-clinic customer, based on the service-quality perception (SERVQUAL), loyalty, Relational Marketing and some relevant socio-economical characteristics, of the dental-clinic customers. In particular, the field study has been developed in the geographical region of Madrid, Spain during the years 2012 and 2013. The first stage of the preparation of the model consist in the data gathering process. For this purpose, five interviews where realized to expert dentists and also two different types of surveys: one for the universe defined by the set of dental-clinic patients and the second for the universe defined by the set of the dentists of the dental clinics of the Madrid Community. A sample of 200 surveys where collected for patients and a sample of 220 surveys where collected from active dentists belonging to the Ilustre Colegio Oficial de Odontólogos y Estomatólogos de la I Región Madrid. In the second stage of the model preparation, the processes of data-analysis, induction and synthesis of the final model where performed. The Graphic Probabilistic Models methodology was used to elaborate the final model, specifically, a Bayesian Network, where the variables (nodes) and their statistical and causal dependencies where integrated and modeled, representing thus, the obtained knowledge from the data obtained by the surveys and the scientific knowledge derived from previous research in the field. A Bayesian Net consisting on six principal nodes was obtained, of which two of them are directly observable: “Revisit Intention” y “SERVQUAL”, and the remaining four are submodels (a grouping of variables). These are: “Attitudinal”, “Disease Information”, “Socioeconomical” and “Services”. The main conclusions derived from the model, as an inference tool, and the analysis of the interviews are: (i) the variables inside the “Attitudinal” node are the most sensitive and significant. By making some particular imputations on the variables that conform the “Attitudinal” node (“RelationalMk”, “Satisfaction”, “Recommendation” y “Friendship”), high posterior probabilities (measured in revisit intention) are obtained for the loyalty of the dental-clinic patient. (ii) In the “Disease Information” node, the causal relation between the “Perception of disease” and “SERVQUAL” when “Perception of disease” is imputed is highlighted, showing that the perception of the severity of the patient’s disease conditions significantly the perception of service quality. As an example, by imputing some particular values to the “Clinic_Type” node high posterior probabilities are obtained for the “SERVQUAL” variables and for “Revisit Intention” showing that the clinic type influences significantly in the service quality perception and loyalty (revisit intention). (iii) In the “Socioeconomical” variable, the variable “Sex” showed to be non-significant, however, the “Age” variable and “Income” show high variability in its posterior probabilities when some variable from the “Services” node where imputed, showing thus, that these variables condition the intention to buy new services (“Services”), especially in the age range from 30 to 50 years in patients with incomes between 3000€ and 4000€. (iv) In the “Services” submodel the dental-clinic patients show high priors to buy services such as oral and gingival therapy, Dental Health Education and “Parking” service. (v) The obtained loyalty measures, from the behavioral perspective, “Visit/year” and “Time_clinic”, do not add significant information to the model. Neither the attitudinal loyalty component “Churn Efford”. (vi) From the interviews realized to the expert dentists it is observed that the owners of the traditional clinics have a low propensity to apply new commercial strategies due to a lack of resources and tools. In general, there exists an opposition to new business models in the sector, especially to the franchise dental model. All of this evidences a lack in business management in the sector. As future lines of research, a deep look into some statistical and causal relations is proposed, such as: SERVQUALServices; SatisfactionServices; RelationalMKServices, Perception of diseaseSatisfaction, as well as new measurement variables related to attitudinal loyalty that contribute to improve the model, for example, profit per patient and per visit.

Polyandrous females discriminate against previous mates

In most animal species, particularly those in which females engage in polyandry, mate choice is a sequential process in which a female must choose to mate or not to mate with each male encountered. Although a number of theoretical and empirical investigations have examined the effects of sequential mate choice on the operation of sexual selection, how females respond to solicitation by previous mates has received little attention. Here, we report the results of a study carried out on the polyandrous pseudoscorpion, Cordylochernes scorpioides, that assessed the sexual receptivity of once-mated females presented after a lapse of 1.5 hr or 48 hr with either their first mate or a different male. Females exhibited a high level of receptivity to new males, irrespective of intermating interval. By contrast, time between matings exerted a strong effect on female receptivity to previous mates. After a lapse of 48 hr, females did not differ significantly in their receptivity toward previous mates and different males, whereas at 1.5 hr after first mating, females were almost invariably unreceptive to males from whom they had previously accepted sperm. This result could not be attributed to male size or mating experience or to male sexual receptivity. Indeed, males were as willing to transfer sperm to a previous mate as they were to a new female. This difference between males and females in their propensity to remate with the same individual may reflect a conflict between the sexes, with males seeking to minimize postcopulatory sexual selection and females actively keeping open the opportunity for sperm competition and female choice of sperm by discriminating against previous mates.

N-Methyl-d-aspartate antagonists and apoptotic cell death triggered by head trauma in developing rat brain

Morbidity and mortality from head trauma is highest among children. No animal model mimicking traumatic brain injury in children has yet been established, and the mechanisms of neuronal degeneration after traumatic injury to the developing brain are not understood. In infant rats subjected to percussion head trauma, two types of brain damage could be characterized. The first type or primary damage evolved within 4 hr and occurred by an excitotoxic mechanism. The second type or secondary damage evolved within 6–24 hr and occurred by an apoptotic mechanism. Primary damage remained localized to the parietal cortex at the site of impact. Secondary damage affected distant sites such as the cingulate/retrosplenial cortex, subiculum, frontal cortex, thalamus and striatum. Secondary apoptotic damage was more severe than primary excitotoxic damage. Morphometric analysis demonstrated that the N-methyl-d-aspartate receptor antagonists 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonate and dizocilpine protected against primary excitotoxic damage but increased severity of secondary apoptotic damage. 2-Sulfo-α-phenyl-N-tert-butyl-nitrone, a free radical scavenger, did not affect primary excitotoxic damage but mitigated apoptotic damage. These observations demonstrate that apoptosis and not excitotoxicity determine neuropathologic outcome after traumatic injury to the developing brain. Whereas free radical scavengers may prove useful in therapy of head trauma in children, N-methyl-d-aspartate antagonists should be avoided because of their propensity to increase severity of apoptotic damage.

Glutamate antagonists limit tumor growth

Neuronal progenitors and tumor cells possess propensity to proliferate and to migrate. Glutamate regulates proliferation and migration of neurons during development, but it is not known whether it influences proliferation and migration of tumor cells. We demonstrate that glutamate antagonists inhibit proliferation of human tumor cells. Colon adenocarcinoma, astrocytoma, and breast and lung carcinoma cells were most sensitive to the antiproliferative effect of the N-methyl-d-aspartate antagonist dizocilpine, whereas breast and lung carcinoma, colon adenocarcinoma, and neuroblastoma cells responded most favorably to the α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate antagonist GYKI52466. The antiproliferative effect of glutamate antagonists was Ca2+ dependent and resulted from decreased cell division and increased cell death. Morphological alterations induced by glutamate antagonists in tumor cells consisted of reduced membrane ruffling and pseudopodial protrusions. Furthermore, glutamate antagonists decreased motility and invasive growth of tumor cells. These findings suggest anticancer potential of glutamate antagonists.

The [(G/C)3NN]n motif: a common DNA repeat that excludes nucleosomes.

Nucleosomes, the basic structural elements of chromosomes, consist of 146 bp of DNA coiled around an octamer of histone proteins, and their presence can strongly influence gene expression. Considerations of the anisotropic flexibility of nucleotide triplets containing 3 cytosines or guanines suggested that a [5'(G/C)3 NN3']n motif might resist wrapping around a histone octamer. To test this, DNAs were constructed containing a 5'-CCGNN-3' pentanucleotide repeat with the Ns varied. Using in vitro nucleosome reconstitution and electron microscopy, a plasmid with 48 contiguous CCGNN repeats strongly excluded nucleosomes in the repeat region. Competitive reconstitution gel retardation experiments using DNA fragments containing 12, 24, or 48 CCGNN repeats showed that the propensity to exclude nucleosomes increased with the length of the repeat. Analysis showed that a 268-bp DNA containing a (CCGNN)48 block is 4.9 +/- 0.6-fold less efficient in nucleosome assembly than a similar length pUC19 fragment and approximately 78-fold less efficient than a similar length (CTG)n sequence, based on results from previous studies. Computer searches against the GenBank database for matches with a [(G/C)3NN]48 sequence revealed numerous examples that frequently were present in the control regions of "TATA-less" genes, including the human ETS-2 and human dihydrofolate reductase genes. In both cases the (G/C)3NN repeat, present in the promoter region, co-maps with loci previously shown to be nuclease hypersensitive sites.

Catalytic domain of human immunodeficiency virus type 1 integrase: identification of a soluble mutant by systematic replacement of hydrophobic residues.

The integrase protein of human immunodeficiency virus type 1 is necessary for the stable integration of the viral genome into host DNA. Integrase catalyzes the 3' processing of the linear viral DNA and the subsequent DNA strand transfer reaction that inserts the viral DNA ends into host DNA. Although full-length integrase is required for 3' processing and DNA strand transfer activities in vitro, the central core domain of integrase is sufficient to catalyze an apparent reversal of the DNA strand transfer reaction, termed disintegration. This catalytic core domain, as well as the full-length integrase, has been refractory to structural studies by x-ray crystallography or NMR because of its low solubility and propensity to aggregate. In an attempt to improve protein solubility, we used site-directed mutagenesis to replace hydrophobic residues within the core domain with either alanine or lysine. The single substitution of lysine for phenylalanine at position 185 resulted in a core domain that was highly soluble, monodisperse in solution, and retained catalytic activity. This amino acid change has enabled the catalytic domain of integrase to be crystallized and the structure has been solved to 2.5-A resolution [Dyda, F., Hickman, A. B., Jenkins, T. M., Engelman, A., Craigie, R. & Davies, D. R. (1994) Science 266, 1981-1986]. Systematic replacement of hydrophobic residues may be a useful strategy to improve the solubility of other proteins to facilitate structural and biochemical studies.