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Papers by jorge pacheco

Evaluación del ambiente educacional pre-clínico en 6 Escuelas de Medicina en Chile

Revista Medica De Chile, Jun 3, 2010

Evaluation of the undergraduate educational environment in six medical schools in Chile Backgroun... more Evaluation of the undergraduate educational environment in six medical schools in Chile Background: The Dundee Ready Education Environment Measure (DREEM) is the most valid and reliable instrument to measure the educational environment (EE) in undergraduate medical education. Aim: To evaluate the EE perceived by undergraduate medical students in Chile, using a Spanish version of the DREEM questionnaire. Material and Methods: The DREEM was applied during 2008 in third, fourth and fifth undergraduate years of six medical schools. The individual results were calculated and means of both global and individual domain scores of the DREEM were compared, by year, gender and between different Schools. Results: One thousand ninety two students (77% of the total universe of students), answered the questionnaire. The mean score of the six Schools was 113.9. The domains of Perception of Learning and Social Self-Perception obtained the lower scores, with a global outcome indicating a more positive than negative EE. Two schools obtained mean scores of 128.32 and 126.87, that were significantly higher than the global scores obtained by other schools. No relevant differences by years or gender were observed. Conclusions: There is a significant variability between the six schools evaluated and two of these obtained significantly better scores than the rest. The identified positive and negative areas will orient the actions to improve the EE for undergraduate medical students.

A pilot study of the frequency of genital tract infection in symptomatic women and the use of rapid diagnostic tests in two groups of women from Bogotá, Colombia, 2008

Revista Colombiana De Obstetricia Y Ginecologia, Sep 1, 2010

Objetivo: describir la frecuencia y etiología de las infecciones del tracto genital (ITG), en muj... more Objetivo: describir la frecuencia y etiología de las infecciones del tracto genital (ITG), en mujeres con flujo vaginal. Metodología: este fue un estudio de corte transversal en el que participaron mujeres de 14 a 49 años con sintomatología genital que consultaron durante 2007 y 2008 a tres centros de atención especializada en Bogotá (Colombia). Se excluyeron mujeres que presentaban condiciones médicas severas, con antecedente de histerectomía, embarazadas y aquellas que hubieran recibido algún tipo de tratamiento antibiótico en los últimos

Ontogenia del reflejo de inmovilidad en ratas con catalepsia inducida por haloperidol

by Fidel De-La-Cruz and jorge pacheco

Anales De La Escuela Nacional De Ciencias Biologicas, 1998

Frecuencia de infecciones del tracto genital femenino en mujeres sintomáticas y uso de pruebas rápidas para su diagnóstico en dos poblaciones de Bogotá (Colombia) 2008: Estudio piloto

Revista Colombiana De Obstetricia Y Ginecologia, Sep 1, 2010

Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto

Structural transitions and transport in a molecular switch

Aps March Meeting Abstracts, Mar 1, 2001

We study the energetics, electronic structure and electron transport through neutral and charged ... more We study the energetics, electronic structure and electron transport through neutral and charged oligo(phenylene ethylene) molecules within a self-assembled monolayer sandwiched between parallel gold electrodes. Our results indicate that a net charge transfer to the molecules, induced by applying a bias voltage, may shift the balance between the pi-system conjugation and the Coulomb repulsion within the system, thus inducing a

Evolutionary dynamics of collective index insurance

Journal of mathematical biology, Jan 20, 2015

Index-based insurances offer promising opportunities for climate-risk investments in developing c... more Index-based insurances offer promising opportunities for climate-risk investments in developing countries. Indeed, contracts conditional on, e.g., weather or livestock indexes can be cheaper to set up than conventional indemnity-based insurances, while offering a safety net to vulnerable households, allowing them to eventually escape poverty traps. Moreover, transaction costs by insurance companies may be additionally reduced if contracts, instead of arranged with single households, are endorsed by collectives of households that bear the responsibility of managing the division of the insurance coverage by its members whenever the index is surpassed, allowing for additional flexibility in what concerns risk-sharing and also allowing insurance companies to avoid the costs associated with moral hazard. Here we resort to a population dynamics framework to investigate under which conditions household collectives may find collective index insurances attractive, when compared with individu...

[Evaluation of the undergraduate educational environment in six medical schools in Chile]

Revista medica de Chile

Evaluation of the undergraduate educational environment in six medical schools in Chile Backgroun... more Evaluation of the undergraduate educational environment in six medical schools in Chile Background: The Dundee Ready Education Environment Measure (DREEM) is the most valid and reliable instrument to measure the educational environment (EE) in undergraduate medical education. Aim: To evaluate the EE perceived by undergraduate medical students in Chile, using a Spanish version of the DREEM questionnaire. Material and Methods: The DREEM was applied during 2008 in third, fourth and fifth undergraduate years of six medical schools. The individual results were calculated and means of both global and individual domain scores of the DREEM were compared, by year, gender and between different Schools. Results: One thousand ninety two students (77% of the total universe of students), answered the questionnaire. The mean score of the six Schools was 113.9. The domains of Perception of Learning and Social Self-Perception obtained the lower scores, with a global outcome indicating a more positive than negative EE. Two schools obtained mean scores of 128.32 and 126.87, that were significantly higher than the global scores obtained by other schools. No relevant differences by years or gender were observed. Conclusions: There is a significant variability between the six schools evaluated and two of these obtained significantly better scores than the rest. The identified positive and negative areas will orient the actions to improve the EE for undergraduate medical students.

DETC2001/DTM-2032 Developing Bayesian Surrogates for Use in Preliminary Design

During the preliminary design stages, designers often have incomplete knowledge about the interac... more During the preliminary design stages, designers often have incomplete knowledge about the interactions among design parameters. We are developing a methodology that will enable designers to create models with levels of detail and accuracy that correspond to the current state of the design knowledge. The methodology uses Bayesian surrogate models that are updated sequentially in stages. Thus, designers can create a rough surrogate model when only a few data points are available and then refine the model as the design progresses and more information becomes available. These surrogates represent the system response when limited information is available and when few realizations of experiments or numerical simulations are possible. This paper presents a covariance-based approach for building surrogates in the preliminary design stages when bounds are not available a priori. We test the methodology using an analytical one-dimensional function and a heat transfer problem with an analytica...

7.I.O.Prevalencia.Ingles

Evolutionary dynamics of group fairness

Journal of Theoretical Biology, 2015

Agreements often involve group decisions where fairness may play a key role. This can be addresse... more Agreements often involve group decisions where fairness may play a key role. This can be addressed through a multiplayer generalization of the Ultimatum Game. We show that imposing consensuses raises the proposals, leading to fairer agreements. Stochastic effects are shown to further enhance group fairness.

Incomplete Cooperation and Co-Benefits: Deepening Climate Cooperation with a Proliferation of Small Agreements

SSRN Electronic Journal, 2015

Case study and model results lend some optimism for the potential of small coalitions with partia... more Case study and model results lend some optimism for the potential of small coalitions with partially excludable public goods to substantially deepen international cooperation on energy and climate issues. Drawing motivation from other issue areas in international relations ranging from nuclear non-proliferation, transboundary air pollution and liberalized trade, we use an evolutionary-game-theoretic model to analyze regimes that yield domestic incentives to contribute to public goods provision (co-benefits). Co-benefits may be limited, but can create a nucleus for formation of coalitions that grow while deepening provision of global public goods. The Climate and Clean Air Coalition (CCAC) is a prime example of an agreement that employs partially excludable club benefits to deepen cooperation on non-CO2 greenhouse gases. Our game-theoretic results support two important insights for the building blocks approach to addressing climate change: sustained cooperation in club agreements is possible even when public goods are not entirely excludable and some members of the population free ride; and second, cooperation in small club configurations yields larger non-excludable public goods benefits than cooperation in more inclusive forums. This paper lends positive support that a proliferation of small agreements under a building blocks approach at the UNFCCC may be more effective (not just more likely) for deepening climate change cooperation than a fully inclusive approach.

Flexible Multistage Bayesian Models for Use in Conceptual Design

Volume 4: 14th International Conference on Design Theory and Methodology, Integrated Systems Design, and Engineering Design and Culture, 2002

During conceptual design, designers need tools to help improve design decisions and reduce design... more During conceptual design, designers need tools to help improve design decisions and reduce design times. We are working to develop techniques to create Bayesian surrogate models that respond to designers’ needs during conceptual stages of the design process. Bayesian surrogate models give analytical form to the overall performance of a system and can evolve along with the design. Bayesian surrogate models provide a mathematically rigorous framework in which computational models can be updated based on previous outcomes. In this paper, we present techniques that allow the addition or suppression of parameters without discarding previously obtained information. We also present a case study that illustrates how a surrogate model is constructed in stages when parameters are added or suppressed during the design process. Visualization tools, such as plots of the main effects of parameters, can be derived from surrogate models. These tools can be used to provide knowledge about the parame...

Senior Undergraduate Design Project for the Development of a Pressurized Connector Spool

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Education; Electric Power; Manufacturing Materials and Metallurgy, 2010

This paper presents the objectives, design procedure and results of a senior design project durin... more This paper presents the objectives, design procedure and results of a senior design project during the spring semester of 2009. A team of five mechanical engineering senior students were challenged to design a pressurized connector spool for the original equipment manufacturer’s Integrated Compression System (ICS). This system is comprised of two modules: a separator/compressor and a high-speed, direct drive electric motor. In this concept, the motor and separator/compressor each are mounted on two magnetic bearings and their shafts are connected together using a flexible coupling. Because the flexible coupling has to be installed after both of the individual shafts are inserted into their casings (from opposite ends), the connector spool accessibility is a main concern. The students developed eight initial concepts that were compared using a concept screening matrix. The top two scored ideas were selected for further review. One dimensional simplified calculations were performed to...

Fluctuations in the shape transitions of hot nuclei

Physical Review Letters, 1988

The effect of quantal and thermal quadrupole shape fluctuations in the giant dipole response func... more The effect of quantal and thermal quadrupole shape fluctuations in the giant dipole response function of hot nuclei at high spin is studied within the Landau theory of phase transitions. The effects are found to be important in the relation of the nuclear shape to the experimental findings, and in the identification of shape phase transitions.

Microscopic structure of the plasma resonance in charged potassium microclusters

Physical Review B, 1990

The Rapid Communications section is intended for the accelerated publication of important new res... more The Rapid Communications section is intended for the accelerated publication of important new results. Since manuscripts submitted to this section are given priority treatment both in the editorial once and in productiona, uthors should explain in their submittal letter why the work justijies this special handling A Rapid Communication should be no longer than 3Vz printed pages and must be accompanied by an abstract. Page proofs are sent to authors, but, because of the accelerated schedule, publication is not delayed for receipt of corrections unless requested by the author or noted by the editor Microscopic structure of the plasma resonance in charged potassium microclusters

Evaluación del ambiente educacional pre-clínico en seis Escuelas de Medicina en Chile

Revista médica de Chile, 2010

Evaluation of the undergraduate educational environment in six medical schools in Chile Backgroun... more Evaluation of the undergraduate educational environment in six medical schools in Chile Background: The Dundee Ready Education Environment Measure (DREEM) is the most valid and reliable instrument to measure the educational environment (EE) in undergraduate medical education. Aim: To evaluate the EE perceived by undergraduate medical students in Chile, using a Spanish version of the DREEM questionnaire. Material and Methods: The DREEM was applied during 2008 in third, fourth and fifth undergraduate years of six medical schools. The individual results were calculated and means of both global and individual domain scores of the DREEM were compared, by year, gender and between different Schools. Results: One thousand ninety two students (77% of the total universe of students), answered the questionnaire. The mean score of the six Schools was 113.9. The domains of Perception of Learning and Social Self-Perception obtained the lower scores, with a global outcome indicating a more positive than negative EE. Two schools obtained mean scores of 128.32 and 126.87, that were significantly higher than the global scores obtained by other schools. No relevant differences by years or gender were observed. Conclusions: There is a significant variability between the six schools evaluated and two of these obtained significantly better scores than the rest. The identified positive and negative areas will orient the actions to improve the EE for undergraduate medical students.

Forecasting in a Multi-skill Call Centre

by Ignacio Hidalgo and jorge pacheco

Lecture Notes in Computer Science, 2010

Page 1. L. Rutkowski et al. (Eds.): ICAISC 2010, Part II, LNAI 6114, pp. 582589, 2010. © Springe... more

In silico evolutionary dynamics of tumour virotherapy

Integr. Biol., 2010

We discretize real 3D space into a regular mesh, a Face Centred Cubic (FCC) lattice. The FCC latt... more

Potentiation of the immobility response elicited by bandaging and clamping in mesencephalic rats

by Fidel De-La-Cruz and jorge pacheco

Physiology & Behavior, 1995

BEHAV 58(4) 737-742, 1995.--In earlier work, we showed that adult rats exhibit immobility respons... more BEHAV 58(4) 737-742, 1995.--In earlier work, we showed that adult rats exhibit immobility response (IR) ff a clamp is fastened to the skin of the nape of the neck, but not at other areas of the body, and not by bandaging. The present study characterizes IR in adult rats with complete mesencephalic transections. In the mesencephalic rats, the duration of the IR not only increased, but the stimuli capable of eliciting it were more diverse. All head and body areas clamped or bandaged were capable of inducing a profound IR. In contrast, the IR in intact rats was of shorter duration, and was only induced by damping the neck, or by bandaging the upper or the lower torso. Furthermore, unlike the mesencephalic rats the ability of the bandaging to induce IR is reduced after the first trial and finally disappears. Only clamping the neck was able to persistently induce IR in intact rats. These data support the hypothesis that the IR corttrol system is in the midbrain, hindbrain or spinal cord, and that systems above the mesencephalon modulate the IR. Such modulation appears to involve the ability to discriminate amongst tactile stimuli, and to integrate previous experience.

Incipient Cognition Solves the Spatial Reciprocity Conundrum of Cooperation

PLoS ONE, 2011

Background: From the simplest living organisms to human societies, cooperation among individuals ... more Background: From the simplest living organisms to human societies, cooperation among individuals emerges as a paradox difficult to explain and describe mathematically, although very often observed in reality. Evolutionary game theory offers an excellent toolbar to investigate this issue. Spatial structure has been one of the first mechanisms promoting cooperation; however, alone it only opens a narrow window of viability. Methodology/Principal Findings: Here we equip individuals with incipient cognitive abilities, and investigate the evolution of cooperation in a spatial world where retaliation, forgiveness, treason and mutualism may coexist, as individuals engage in Prisoner's Dilemma games. In the model, individuals are able to distinguish their partners and act towards them based on previous interactions. We show how the simplest level of cognition, alone, can lead to the emergence of cooperation. Conclusions/Significance: Despite the incipient nature of the individuals' cognitive abilities, cooperation emerges for unprecedented values of the temptation to cheat, being also robust to invasion by cheaters, errors in decision making and inaccuracy of imitation, features akin to many species, including humans.

Evaluación del ambiente educacional pre-clínico en 6 Escuelas de Medicina en Chile

Revista Medica De Chile, Jun 3, 2010

Evaluation of the undergraduate educational environment in six medical schools in Chile Backgroun... more Evaluation of the undergraduate educational environment in six medical schools in Chile Background: The Dundee Ready Education Environment Measure (DREEM) is the most valid and reliable instrument to measure the educational environment (EE) in undergraduate medical education. Aim: To evaluate the EE perceived by undergraduate medical students in Chile, using a Spanish version of the DREEM questionnaire. Material and Methods: The DREEM was applied during 2008 in third, fourth and fifth undergraduate years of six medical schools. The individual results were calculated and means of both global and individual domain scores of the DREEM were compared, by year, gender and between different Schools. Results: One thousand ninety two students (77% of the total universe of students), answered the questionnaire. The mean score of the six Schools was 113.9. The domains of Perception of Learning and Social Self-Perception obtained the lower scores, with a global outcome indicating a more positive than negative EE. Two schools obtained mean scores of 128.32 and 126.87, that were significantly higher than the global scores obtained by other schools. No relevant differences by years or gender were observed. Conclusions: There is a significant variability between the six schools evaluated and two of these obtained significantly better scores than the rest. The identified positive and negative areas will orient the actions to improve the EE for undergraduate medical students.

A pilot study of the frequency of genital tract infection in symptomatic women and the use of rapid diagnostic tests in two groups of women from Bogotá, Colombia, 2008

Revista Colombiana De Obstetricia Y Ginecologia, Sep 1, 2010

Objetivo: describir la frecuencia y etiología de las infecciones del tracto genital (ITG), en muj... more Objetivo: describir la frecuencia y etiología de las infecciones del tracto genital (ITG), en mujeres con flujo vaginal. Metodología: este fue un estudio de corte transversal en el que participaron mujeres de 14 a 49 años con sintomatología genital que consultaron durante 2007 y 2008 a tres centros de atención especializada en Bogotá (Colombia). Se excluyeron mujeres que presentaban condiciones médicas severas, con antecedente de histerectomía, embarazadas y aquellas que hubieran recibido algún tipo de tratamiento antibiótico en los últimos

Ontogenia del reflejo de inmovilidad en ratas con catalepsia inducida por haloperidol

by Fidel De-La-Cruz and jorge pacheco

Anales De La Escuela Nacional De Ciencias Biologicas, 1998

Frecuencia de infecciones del tracto genital femenino en mujeres sintomáticas y uso de pruebas rápidas para su diagnóstico en dos poblaciones de Bogotá (Colombia) 2008: Estudio piloto

Revista Colombiana De Obstetricia Y Ginecologia, Sep 1, 2010

Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto

Structural transitions and transport in a molecular switch

Aps March Meeting Abstracts, Mar 1, 2001

We study the energetics, electronic structure and electron transport through neutral and charged ... more We study the energetics, electronic structure and electron transport through neutral and charged oligo(phenylene ethylene) molecules within a self-assembled monolayer sandwiched between parallel gold electrodes. Our results indicate that a net charge transfer to the molecules, induced by applying a bias voltage, may shift the balance between the pi-system conjugation and the Coulomb repulsion within the system, thus inducing a

Evolutionary dynamics of collective index insurance

Journal of mathematical biology, Jan 20, 2015

Index-based insurances offer promising opportunities for climate-risk investments in developing c... more Index-based insurances offer promising opportunities for climate-risk investments in developing countries. Indeed, contracts conditional on, e.g., weather or livestock indexes can be cheaper to set up than conventional indemnity-based insurances, while offering a safety net to vulnerable households, allowing them to eventually escape poverty traps. Moreover, transaction costs by insurance companies may be additionally reduced if contracts, instead of arranged with single households, are endorsed by collectives of households that bear the responsibility of managing the division of the insurance coverage by its members whenever the index is surpassed, allowing for additional flexibility in what concerns risk-sharing and also allowing insurance companies to avoid the costs associated with moral hazard. Here we resort to a population dynamics framework to investigate under which conditions household collectives may find collective index insurances attractive, when compared with individu...

[Evaluation of the undergraduate educational environment in six medical schools in Chile]

Revista medica de Chile

Evaluation of the undergraduate educational environment in six medical schools in Chile Backgroun... more Evaluation of the undergraduate educational environment in six medical schools in Chile Background: The Dundee Ready Education Environment Measure (DREEM) is the most valid and reliable instrument to measure the educational environment (EE) in undergraduate medical education. Aim: To evaluate the EE perceived by undergraduate medical students in Chile, using a Spanish version of the DREEM questionnaire. Material and Methods: The DREEM was applied during 2008 in third, fourth and fifth undergraduate years of six medical schools. The individual results were calculated and means of both global and individual domain scores of the DREEM were compared, by year, gender and between different Schools. Results: One thousand ninety two students (77% of the total universe of students), answered the questionnaire. The mean score of the six Schools was 113.9. The domains of Perception of Learning and Social Self-Perception obtained the lower scores, with a global outcome indicating a more positive than negative EE. Two schools obtained mean scores of 128.32 and 126.87, that were significantly higher than the global scores obtained by other schools. No relevant differences by years or gender were observed. Conclusions: There is a significant variability between the six schools evaluated and two of these obtained significantly better scores than the rest. The identified positive and negative areas will orient the actions to improve the EE for undergraduate medical students.

DETC2001/DTM-2032 Developing Bayesian Surrogates for Use in Preliminary Design

During the preliminary design stages, designers often have incomplete knowledge about the interac... more During the preliminary design stages, designers often have incomplete knowledge about the interactions among design parameters. We are developing a methodology that will enable designers to create models with levels of detail and accuracy that correspond to the current state of the design knowledge. The methodology uses Bayesian surrogate models that are updated sequentially in stages. Thus, designers can create a rough surrogate model when only a few data points are available and then refine the model as the design progresses and more information becomes available. These surrogates represent the system response when limited information is available and when few realizations of experiments or numerical simulations are possible. This paper presents a covariance-based approach for building surrogates in the preliminary design stages when bounds are not available a priori. We test the methodology using an analytical one-dimensional function and a heat transfer problem with an analytica...

7.I.O.Prevalencia.Ingles

Evolutionary dynamics of group fairness

Journal of Theoretical Biology, 2015

Agreements often involve group decisions where fairness may play a key role. This can be addresse... more Agreements often involve group decisions where fairness may play a key role. This can be addressed through a multiplayer generalization of the Ultimatum Game. We show that imposing consensuses raises the proposals, leading to fairer agreements. Stochastic effects are shown to further enhance group fairness.

Incomplete Cooperation and Co-Benefits: Deepening Climate Cooperation with a Proliferation of Small Agreements

SSRN Electronic Journal, 2015

Case study and model results lend some optimism for the potential of small coalitions with partia... more Case study and model results lend some optimism for the potential of small coalitions with partially excludable public goods to substantially deepen international cooperation on energy and climate issues. Drawing motivation from other issue areas in international relations ranging from nuclear non-proliferation, transboundary air pollution and liberalized trade, we use an evolutionary-game-theoretic model to analyze regimes that yield domestic incentives to contribute to public goods provision (co-benefits). Co-benefits may be limited, but can create a nucleus for formation of coalitions that grow while deepening provision of global public goods. The Climate and Clean Air Coalition (CCAC) is a prime example of an agreement that employs partially excludable club benefits to deepen cooperation on non-CO2 greenhouse gases. Our game-theoretic results support two important insights for the building blocks approach to addressing climate change: sustained cooperation in club agreements is possible even when public goods are not entirely excludable and some members of the population free ride; and second, cooperation in small club configurations yields larger non-excludable public goods benefits than cooperation in more inclusive forums. This paper lends positive support that a proliferation of small agreements under a building blocks approach at the UNFCCC may be more effective (not just more likely) for deepening climate change cooperation than a fully inclusive approach.

Flexible Multistage Bayesian Models for Use in Conceptual Design

Volume 4: 14th International Conference on Design Theory and Methodology, Integrated Systems Design, and Engineering Design and Culture, 2002

During conceptual design, designers need tools to help improve design decisions and reduce design... more During conceptual design, designers need tools to help improve design decisions and reduce design times. We are working to develop techniques to create Bayesian surrogate models that respond to designers’ needs during conceptual stages of the design process. Bayesian surrogate models give analytical form to the overall performance of a system and can evolve along with the design. Bayesian surrogate models provide a mathematically rigorous framework in which computational models can be updated based on previous outcomes. In this paper, we present techniques that allow the addition or suppression of parameters without discarding previously obtained information. We also present a case study that illustrates how a surrogate model is constructed in stages when parameters are added or suppressed during the design process. Visualization tools, such as plots of the main effects of parameters, can be derived from surrogate models. These tools can be used to provide knowledge about the parame...

Senior Undergraduate Design Project for the Development of a Pressurized Connector Spool

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Education; Electric Power; Manufacturing Materials and Metallurgy, 2010

This paper presents the objectives, design procedure and results of a senior design project durin... more This paper presents the objectives, design procedure and results of a senior design project during the spring semester of 2009. A team of five mechanical engineering senior students were challenged to design a pressurized connector spool for the original equipment manufacturer’s Integrated Compression System (ICS). This system is comprised of two modules: a separator/compressor and a high-speed, direct drive electric motor. In this concept, the motor and separator/compressor each are mounted on two magnetic bearings and their shafts are connected together using a flexible coupling. Because the flexible coupling has to be installed after both of the individual shafts are inserted into their casings (from opposite ends), the connector spool accessibility is a main concern. The students developed eight initial concepts that were compared using a concept screening matrix. The top two scored ideas were selected for further review. One dimensional simplified calculations were performed to...

Fluctuations in the shape transitions of hot nuclei

Physical Review Letters, 1988

The effect of quantal and thermal quadrupole shape fluctuations in the giant dipole response func... more The effect of quantal and thermal quadrupole shape fluctuations in the giant dipole response function of hot nuclei at high spin is studied within the Landau theory of phase transitions. The effects are found to be important in the relation of the nuclear shape to the experimental findings, and in the identification of shape phase transitions.

Microscopic structure of the plasma resonance in charged potassium microclusters

Physical Review B, 1990

The Rapid Communications section is intended for the accelerated publication of important new res... more The Rapid Communications section is intended for the accelerated publication of important new results. Since manuscripts submitted to this section are given priority treatment both in the editorial once and in productiona, uthors should explain in their submittal letter why the work justijies this special handling A Rapid Communication should be no longer than 3Vz printed pages and must be accompanied by an abstract. Page proofs are sent to authors, but, because of the accelerated schedule, publication is not delayed for receipt of corrections unless requested by the author or noted by the editor Microscopic structure of the plasma resonance in charged potassium microclusters

Evaluación del ambiente educacional pre-clínico en seis Escuelas de Medicina en Chile

Revista médica de Chile, 2010

Evaluation of the undergraduate educational environment in six medical schools in Chile Backgroun... more Evaluation of the undergraduate educational environment in six medical schools in Chile Background: The Dundee Ready Education Environment Measure (DREEM) is the most valid and reliable instrument to measure the educational environment (EE) in undergraduate medical education. Aim: To evaluate the EE perceived by undergraduate medical students in Chile, using a Spanish version of the DREEM questionnaire. Material and Methods: The DREEM was applied during 2008 in third, fourth and fifth undergraduate years of six medical schools. The individual results were calculated and means of both global and individual domain scores of the DREEM were compared, by year, gender and between different Schools. Results: One thousand ninety two students (77% of the total universe of students), answered the questionnaire. The mean score of the six Schools was 113.9. The domains of Perception of Learning and Social Self-Perception obtained the lower scores, with a global outcome indicating a more positive than negative EE. Two schools obtained mean scores of 128.32 and 126.87, that were significantly higher than the global scores obtained by other schools. No relevant differences by years or gender were observed. Conclusions: There is a significant variability between the six schools evaluated and two of these obtained significantly better scores than the rest. The identified positive and negative areas will orient the actions to improve the EE for undergraduate medical students.

Forecasting in a Multi-skill Call Centre

by Ignacio Hidalgo and jorge pacheco

Lecture Notes in Computer Science, 2010

Page 1. L. Rutkowski et al. (Eds.): ICAISC 2010, Part II, LNAI 6114, pp. 582589, 2010. © Springe... more

In silico evolutionary dynamics of tumour virotherapy

Integr. Biol., 2010

We discretize real 3D space into a regular mesh, a Face Centred Cubic (FCC) lattice. The FCC latt... more

Potentiation of the immobility response elicited by bandaging and clamping in mesencephalic rats

by Fidel De-La-Cruz and jorge pacheco

Physiology & Behavior, 1995

BEHAV 58(4) 737-742, 1995.--In earlier work, we showed that adult rats exhibit immobility respons... more BEHAV 58(4) 737-742, 1995.--In earlier work, we showed that adult rats exhibit immobility response (IR) ff a clamp is fastened to the skin of the nape of the neck, but not at other areas of the body, and not by bandaging. The present study characterizes IR in adult rats with complete mesencephalic transections. In the mesencephalic rats, the duration of the IR not only increased, but the stimuli capable of eliciting it were more diverse. All head and body areas clamped or bandaged were capable of inducing a profound IR. In contrast, the IR in intact rats was of shorter duration, and was only induced by damping the neck, or by bandaging the upper or the lower torso. Furthermore, unlike the mesencephalic rats the ability of the bandaging to induce IR is reduced after the first trial and finally disappears. Only clamping the neck was able to persistently induce IR in intact rats. These data support the hypothesis that the IR corttrol system is in the midbrain, hindbrain or spinal cord, and that systems above the mesencephalon modulate the IR. Such modulation appears to involve the ability to discriminate amongst tactile stimuli, and to integrate previous experience.

Incipient Cognition Solves the Spatial Reciprocity Conundrum of Cooperation

PLoS ONE, 2011

Background: From the simplest living organisms to human societies, cooperation among individuals ... more Background: From the simplest living organisms to human societies, cooperation among individuals emerges as a paradox difficult to explain and describe mathematically, although very often observed in reality. Evolutionary game theory offers an excellent toolbar to investigate this issue. Spatial structure has been one of the first mechanisms promoting cooperation; however, alone it only opens a narrow window of viability. Methodology/Principal Findings: Here we equip individuals with incipient cognitive abilities, and investigate the evolution of cooperation in a spatial world where retaliation, forgiveness, treason and mutualism may coexist, as individuals engage in Prisoner's Dilemma games. In the model, individuals are able to distinguish their partners and act towards them based on previous interactions. We show how the simplest level of cognition, alone, can lead to the emergence of cooperation. Conclusions/Significance: Despite the incipient nature of the individuals' cognitive abilities, cooperation emerges for unprecedented values of the temptation to cheat, being also robust to invasion by cheaters, errors in decision making and inaccuracy of imitation, features akin to many species, including humans.