Andres Mejia | Universidad de Antioquia (Colombia) (original) (raw)
Papers by Andres Mejia
2017 Congreso Internacional de Innovacion y Tendencias en Ingenieria (CONIITI), 2017
This paper was designed to measure the Colombian sense of belonging on a student's group at t... more This paper was designed to measure the Colombian sense of belonging on a student's group at the Catholic University of Colombia with a Brain Computer Interface (BCI) device. The experiment consists of a musical incentive, the signature song of the country “Soy Colombiano” (I am Colombian), music generates excitement and this excitement is the parameter measuring the sense of belonging, with the possibility of quantifying it by means of the relevance of the stimulus in the physiological responses.
Neurobiology of Disease, 2021
Barbiturates and benzodiazepines are potent GABA A receptor agonists and strong anticonvulsants. ... more Barbiturates and benzodiazepines are potent GABA A receptor agonists and strong anticonvulsants. In the developing brain they can cause neuronal and oligodendroglia apoptosis, impair synaptogenesis, inhibit neurogenesis and trigger long-term neurocognitive sequelae. In humans, the vulnerable period is projected to extend from the third trimester of pregnancy to the third year of life. Infants with seizures and epilepsies may receive barbiturates, benzodiazepines and their combinations for days, months or years. How exposure duration affects neuropathological sequelae is unknown. Here we investigated toxicity of phenobarbital/midazolam (Pb/M) combination in the developing nonhuman primate brain. Neonatal rhesus monkeys received phenobarbital intravenously, followed by infusion of midazolam over 5 (n = 4) or 24 h (n = 4). Animals were euthanized at 8 or 36 h and brains examined immunohistochemically and stereologically.
PLOS ONE, 2020
Cardiac dysautonomia is a common nonmotor symptom of Parkinson's disease (PD) associated with los... more Cardiac dysautonomia is a common nonmotor symptom of Parkinson's disease (PD) associated with loss of sympathetic innervation to the heart and decreased plasma catecholamines. Disease-modifying strategies for PD cardiac neurodegeneration are not available, and biomarkers of target engagement are lacking. Systemic administration of the catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) recapitulates PD cardiac dysautonomia pathology. We recently used positron emission tomography (PET) to visualize and quantify cardiac sympathetic innervation, oxidative stress, and inflammation in adult male rhesus macaques (Macaca mulatta; n = 10) challenged with 6-OHDA (50mg/kg; i.v.). Twenty-four hours post-intoxication, the animals were blindly and randomly assigned to receive daily doses of the peroxisome proliferator-activated receptor gamma (PPARγ) agonist pioglitazone (n = 5; 5mg/kg p.o.) or placebo (n = 5). Quantification of PET radioligand uptake showed increased oxidative stress and inflammation one week after 6-OHDA which resolved to baseline levels by twelve weeks, at which time pioglitazone-treated animals showed regionally preserved sympathetic innervation. Here we report post mortem characterization of heart and adrenal tissue in these animals compared to age and sex matched normal controls (n = 5). In the heart, 6-OHDA-treated animals showed a significant loss of sympathetic nerve fibers density (tyrosine hydroxylase (TH)-positive fibers). The anatomical distribution of markers of sympathetic innervation (TH) and inflammation (HLA-DR) significantly correlated with respective in vivo PET findings across left ventricle levels and regions. No changes were found in alpha-synuclein immunoreactivity. Additionally, CD36 protein expression was increased at the cardiomyocyte intercalated discs following PPARγ-activation compared to placebo and control groups. Systemic 6-OHDA decreased adrenal medulla expression of catecholamine producing enzymes (TH and aromatic L-amino acid
Nature medicine, Jan 2, 2018
Zika virus (ZIKV) infection is associated with congenital defects and pregnancy loss. Here, we fo... more Zika virus (ZIKV) infection is associated with congenital defects and pregnancy loss. Here, we found that 26% of nonhuman primates infected with Asian/American ZIKV in early gestation experienced fetal demise later in pregnancy despite showing few clinical signs of infection. Pregnancy loss due to asymptomatic ZIKV infection may therefore be a common but under-recognized adverse outcome related to maternal ZIKV infection.
PloS one, 2018
Congenital Zika virus (ZIKV) infection impacts fetal development and pregnancy outcomes. We infec... more Congenital Zika virus (ZIKV) infection impacts fetal development and pregnancy outcomes. We infected a pregnant rhesus macaque with a Puerto Rican ZIKV isolate in the first trimester. The pregnancy was complicated by preterm premature rupture of membranes (PPROM), intraamniotic bacterial infection and fetal demise 49 days post infection (gestational day 95). Significant pathology at the maternal-fetal interface included acute chorioamnionitis, placental infarcts, and leukocytoclastic vasculitis of the myometrial radial arteries. ZIKV RNA was disseminated throughout fetal tissues and maternal immune system tissues at necropsy, as assessed by quantitative RT-PCR for viral RNA. Replicating ZIKV was identified in fetal tissues, maternal uterus, and maternal spleen by fluorescent in situ hybridization for viral replication intermediates. Fetal ocular pathology included a choroidal coloboma, suspected anterior segment dysgenesis, and a dysplastic retina. This is the first report of ocular...
Physics and Chemistry of Liquids
Journal of Chemical & Engineering Data, 2014
We report surface tension measurements, coexisting densities, concentration profiles along the in... more We report surface tension measurements, coexisting densities, concentration profiles along the interfacial region, surface activities, and relative Gibbs adsorption isotherms for binary mixtures of carbon dioxide (CO 2) + n-decane (n-C 10 H 22) at 344.15 K and carbon dioxide (CO 2) + n-eicosane (n-C 20 H 42) at 323.15 K over a pressure range from 0.1 MPa to 10.35 MPa. The results are obtained by employing a broad approach that integrates experiments with both theory and molecular simulations to gain an enhanced multiscale description of the interfacial region. Measurements are based on the use of a high-pressure pendant drop tensiometer coupled to a high-pressure densimeter. Theoretical modeling is carried out using the Square Gradient Theory based on a version of the Statistical Associated Fluid Theory (SAFT-VR Mie) equation of state. At the molecular level, Molecular Dynamics is employed and molecules are represented by the SAFTγ coarse-grained force field. The novelty here is that both the theory and the simulations uniquely share the same underlying intermolecular potentials, hence the experimental data are employed to verify and inform in the same way both the theory and simulations. Reassuringly, theory, experiments, and molecular simulations agree with each other in the description of the bulk phase equilibria and interfacial tension. It is observed that for both mixtures, the interfacial tension decreases as the pressure (or the liquid mole fraction of CO 2) increases. Furthermore, there is quantitative agreement between the theoretical predictions and the results obtained from the molecular simulations of surface activities, concentration profiles along the interfacial region, and relative Gibbs adsorption isotherms at the interfaces. A remarkable high excess adsorption of CO 2 , larger in eicosane than in decane, is detected along the interface.
Fluid Phase Equilibria, 2014
Letter to the Editor Comments on "isobaric (vapor + liquid) equilibria for three binary systems (... more Letter to the Editor Comments on "isobaric (vapor + liquid) equilibria for three binary systems (toluene + anisole, n-butylbenzene + anisole, and guaiacol + anisole) at 101.33 kPa"
Journal of Medical Primatology, 2009
Background-Pediatric hepatic angiosarcoma is a rare condition in children with poor prognosis. Mi... more Background-Pediatric hepatic angiosarcoma is a rare condition in children with poor prognosis. Microscopically this neoplasm has a particular 'Kaposi-form' arrangement. Hemangiosarcoma in non-human primates is a rare finding. Methods-Gross and microscopic examination of a 3-year-old rhesus were performed. Immunohistochemistry was used to characterize the hepatic hemangiosarcoma. Results-The gross necropsy revealed hemoabdomen and a 4 × 3 × 3 cm mass in the liver with multiple smaller masses throughout the hepatic parenchyma. Histopathology confirmed a poorly differentiated hemangiosarcoma. Other organs submitted were free of metastases. Conclusions-Hemangiosarcoma in non-human primates has been rarely reported. Diagnosis was confirmed by expression of endothelial-specific markers CD31 and vWF by immunohistochemistry. Due to the young age of this monkey and the particular solid pattern throughout the mass this neoplasm resembles pediatric hepatic angiosarcoma in humans.
Fluid Phase Equilibria, 2008
Isobaric vapor–liquid equilibrium (VLE) data have been measured for the ternary system methyl ter... more Isobaric vapor–liquid equilibrium (VLE) data have been measured for the ternary system methyl tert-butyl ether + acetone + cyclohexane, and for its methyl tert-butyl ether based binaries, at 94 kPa and in the temperature ...
Fluid Phase Equilibria, 2008
An approach for specializing cubic equations of state to the prediction of vapor pressures of pur... more An approach for specializing cubic equations of state to the prediction of vapor pressures of pure fluids is presented. The method is based on a low-temperature asymptotic approximation of the vapor–liquid equilibrium problem which, ...
Fluid Phase Equilibria, 2013
ABSTRACT Isobaric vapor–liquid equilibrium (VLE) data have been measured for the binary system he... more ABSTRACT Isobaric vapor–liquid equilibrium (VLE) data have been measured for the binary system hexane + tetrahydro-2H-pyran at 50, 75, and 94 kPa and over the temperature range 321–358 K using a vapor–liquid equilibrium still with circulation of both phases. Atmospheric surface tension data have been also determined at 303.15 K using a maximum bubble pressure tensiometer. Experimental results show that the mixture is zeotropic and exhibits slight positive deviation from ideal behavior over the experimental range. Surface tensions, in turn, exhibit negative deviation from the linear behavior.The VLE data of the binary mixture satisfy the Fredenlund's consistency test and were well-correlated by the Wohl, nonrandom two-liquid (NRTL), Wilson, and universal quasichemical (UNIQUAC) equations. The dependence of surface tensions on mole fraction was satisfactorily smoothed using the Redlich–Kister equation.The experimental VLE and surface tension data were accurately predicted by applying the square gradient theory to the Peng–Robinson Stryjek–Vera equation of state (EoS), appropriately extended to mixtures with a modified Huron–Vidal mixing rule. This theoretical model was also applied to describe the surface activity of species along the interfacial region, from which it was concluded that hexane presents interfacial accumulation and, therefore, a positive relative Gibbs adsorption isotherm on THP.
Fluid Phase Equilibria, 2008
... PDF (952 K); Export citation; E-mail article; Highlight keywords on: No highlighting Reflect ... more ... PDF (952 K); Export citation; E-mail article; Highlight keywords on: No highlighting Reflect Reflect highlight proteins and chemicals NextBio NextBio highlight relevant biomedical terms. Thumbnails - selected | Full-Size images. ...
Energy, 2012
ABSTRACT An accurate description of the geometry of the temperature-entropy (T-S) diagram is of f... more ABSTRACT An accurate description of the geometry of the temperature-entropy (T-S) diagram is of fundamental importance for predicting the state of working fluids undergoing isentropic processes, as usually required for analyzing the performance of refrigeration and power generation systems. In this contri- bution, rigorous analytical expressions have been obtained for the first and second temperature deriv- atives of the entropy envelope along the vaporeliquid equilibrium (VLE) path of pure fluids. These relationships are valid from the triple point up o the critical state, and have been conveniently expressed in terms of Helmholtz’s energy, thus yielding a generalized method able to describe the geometry of the TeS diagram from typical equation of state (EOS) models. The customary classification of fluids in wet, isentropic or dry behavior has been reduced to a simple criterion based on a new dimensionless function j and how its value compares with the value of the isobaric heat capacity of the ideal gas. Applications are presented for cubic models of the van der Waals type, specific multi-parameter equations, molecular- based models, and virial density expansions. From these results it is concluded that dry behavior depends on the number of atoms that compose the molecule, and it will be generally observed in long-chained molecules.
Educational Action Research, 2008
An action research approach called Soft Systems Methodology (SSM) was used to foster organisation... more An action research approach called Soft Systems Methodology (SSM) was used to foster organisational learning in a school regarding the role of the Learning Support department within the school and its relation with the normal teaching-learning activities. From an initial situation of lack of coordination as well as mutual misunderstanding and distrust among some of the actors in the situation, 8 months of work yielded as a result a better working environment among the participants, the creation of a volunteer discussion group functioning on a permanent basis, and a clarification and modification of some of the Learning Support activities. This change can also be described as a learning by Learning Support staff, school teachers and administrators, on how to work together, as well as on how to support children's learning in a better way. Nevertheless, a further change that occurred after the intervention, shows the importance of considering a wider system than that limited by the participants in the intervention.
Cambridge Journal of Education, 2007
This work is based on the assumption that if the classroom is a space in which manifestations of ... more This work is based on the assumption that if the classroom is a space in which manifestations of critical autonomous thinking appear systematically, then it promotes that same kind of thinking by the students, in other contexts. But what count as manifestations ...
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
The ingestion of alcohol has been linked to characteristic changes in EEG activity, and these cha... more The ingestion of alcohol has been linked to characteristic changes in EEG activity, and these changes depend on several factors. Previous research has been conducted with a variety of experimental designed, but most have focused on reporting the effect of alcohol consumption in subjects with a history of alcohol abuse, and a few have reported the effects of lower doses of alcohol. This project recorded brain activity related to attention in a driving situation with an emotiv EPOC brain control interface (BCI) device after ingestion of 0,300 g of alcohol (0,02 % bac) or none in a preexperiemental pre-test and post-test design with 30 college students aged 18-45. Results suggest that lower doses of alcohol change wave dynamics, reducing the amplitude of fast alpha (9-13Hz) and beta (14-30Hz) waves in frontal lobe zones involved in sustained attention in driving.
2017 Congreso Internacional de Innovacion y Tendencias en Ingenieria (CONIITI), 2017
This paper was designed to measure the Colombian sense of belonging on a student's group at t... more This paper was designed to measure the Colombian sense of belonging on a student's group at the Catholic University of Colombia with a Brain Computer Interface (BCI) device. The experiment consists of a musical incentive, the signature song of the country “Soy Colombiano” (I am Colombian), music generates excitement and this excitement is the parameter measuring the sense of belonging, with the possibility of quantifying it by means of the relevance of the stimulus in the physiological responses.
Neurobiology of Disease, 2021
Barbiturates and benzodiazepines are potent GABA A receptor agonists and strong anticonvulsants. ... more Barbiturates and benzodiazepines are potent GABA A receptor agonists and strong anticonvulsants. In the developing brain they can cause neuronal and oligodendroglia apoptosis, impair synaptogenesis, inhibit neurogenesis and trigger long-term neurocognitive sequelae. In humans, the vulnerable period is projected to extend from the third trimester of pregnancy to the third year of life. Infants with seizures and epilepsies may receive barbiturates, benzodiazepines and their combinations for days, months or years. How exposure duration affects neuropathological sequelae is unknown. Here we investigated toxicity of phenobarbital/midazolam (Pb/M) combination in the developing nonhuman primate brain. Neonatal rhesus monkeys received phenobarbital intravenously, followed by infusion of midazolam over 5 (n = 4) or 24 h (n = 4). Animals were euthanized at 8 or 36 h and brains examined immunohistochemically and stereologically.
PLOS ONE, 2020
Cardiac dysautonomia is a common nonmotor symptom of Parkinson's disease (PD) associated with los... more Cardiac dysautonomia is a common nonmotor symptom of Parkinson's disease (PD) associated with loss of sympathetic innervation to the heart and decreased plasma catecholamines. Disease-modifying strategies for PD cardiac neurodegeneration are not available, and biomarkers of target engagement are lacking. Systemic administration of the catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) recapitulates PD cardiac dysautonomia pathology. We recently used positron emission tomography (PET) to visualize and quantify cardiac sympathetic innervation, oxidative stress, and inflammation in adult male rhesus macaques (Macaca mulatta; n = 10) challenged with 6-OHDA (50mg/kg; i.v.). Twenty-four hours post-intoxication, the animals were blindly and randomly assigned to receive daily doses of the peroxisome proliferator-activated receptor gamma (PPARγ) agonist pioglitazone (n = 5; 5mg/kg p.o.) or placebo (n = 5). Quantification of PET radioligand uptake showed increased oxidative stress and inflammation one week after 6-OHDA which resolved to baseline levels by twelve weeks, at which time pioglitazone-treated animals showed regionally preserved sympathetic innervation. Here we report post mortem characterization of heart and adrenal tissue in these animals compared to age and sex matched normal controls (n = 5). In the heart, 6-OHDA-treated animals showed a significant loss of sympathetic nerve fibers density (tyrosine hydroxylase (TH)-positive fibers). The anatomical distribution of markers of sympathetic innervation (TH) and inflammation (HLA-DR) significantly correlated with respective in vivo PET findings across left ventricle levels and regions. No changes were found in alpha-synuclein immunoreactivity. Additionally, CD36 protein expression was increased at the cardiomyocyte intercalated discs following PPARγ-activation compared to placebo and control groups. Systemic 6-OHDA decreased adrenal medulla expression of catecholamine producing enzymes (TH and aromatic L-amino acid
Nature medicine, Jan 2, 2018
Zika virus (ZIKV) infection is associated with congenital defects and pregnancy loss. Here, we fo... more Zika virus (ZIKV) infection is associated with congenital defects and pregnancy loss. Here, we found that 26% of nonhuman primates infected with Asian/American ZIKV in early gestation experienced fetal demise later in pregnancy despite showing few clinical signs of infection. Pregnancy loss due to asymptomatic ZIKV infection may therefore be a common but under-recognized adverse outcome related to maternal ZIKV infection.
PloS one, 2018
Congenital Zika virus (ZIKV) infection impacts fetal development and pregnancy outcomes. We infec... more Congenital Zika virus (ZIKV) infection impacts fetal development and pregnancy outcomes. We infected a pregnant rhesus macaque with a Puerto Rican ZIKV isolate in the first trimester. The pregnancy was complicated by preterm premature rupture of membranes (PPROM), intraamniotic bacterial infection and fetal demise 49 days post infection (gestational day 95). Significant pathology at the maternal-fetal interface included acute chorioamnionitis, placental infarcts, and leukocytoclastic vasculitis of the myometrial radial arteries. ZIKV RNA was disseminated throughout fetal tissues and maternal immune system tissues at necropsy, as assessed by quantitative RT-PCR for viral RNA. Replicating ZIKV was identified in fetal tissues, maternal uterus, and maternal spleen by fluorescent in situ hybridization for viral replication intermediates. Fetal ocular pathology included a choroidal coloboma, suspected anterior segment dysgenesis, and a dysplastic retina. This is the first report of ocular...
Physics and Chemistry of Liquids
Journal of Chemical & Engineering Data, 2014
We report surface tension measurements, coexisting densities, concentration profiles along the in... more We report surface tension measurements, coexisting densities, concentration profiles along the interfacial region, surface activities, and relative Gibbs adsorption isotherms for binary mixtures of carbon dioxide (CO 2) + n-decane (n-C 10 H 22) at 344.15 K and carbon dioxide (CO 2) + n-eicosane (n-C 20 H 42) at 323.15 K over a pressure range from 0.1 MPa to 10.35 MPa. The results are obtained by employing a broad approach that integrates experiments with both theory and molecular simulations to gain an enhanced multiscale description of the interfacial region. Measurements are based on the use of a high-pressure pendant drop tensiometer coupled to a high-pressure densimeter. Theoretical modeling is carried out using the Square Gradient Theory based on a version of the Statistical Associated Fluid Theory (SAFT-VR Mie) equation of state. At the molecular level, Molecular Dynamics is employed and molecules are represented by the SAFTγ coarse-grained force field. The novelty here is that both the theory and the simulations uniquely share the same underlying intermolecular potentials, hence the experimental data are employed to verify and inform in the same way both the theory and simulations. Reassuringly, theory, experiments, and molecular simulations agree with each other in the description of the bulk phase equilibria and interfacial tension. It is observed that for both mixtures, the interfacial tension decreases as the pressure (or the liquid mole fraction of CO 2) increases. Furthermore, there is quantitative agreement between the theoretical predictions and the results obtained from the molecular simulations of surface activities, concentration profiles along the interfacial region, and relative Gibbs adsorption isotherms at the interfaces. A remarkable high excess adsorption of CO 2 , larger in eicosane than in decane, is detected along the interface.
Fluid Phase Equilibria, 2014
Letter to the Editor Comments on "isobaric (vapor + liquid) equilibria for three binary systems (... more Letter to the Editor Comments on "isobaric (vapor + liquid) equilibria for three binary systems (toluene + anisole, n-butylbenzene + anisole, and guaiacol + anisole) at 101.33 kPa"
Journal of Medical Primatology, 2009
Background-Pediatric hepatic angiosarcoma is a rare condition in children with poor prognosis. Mi... more Background-Pediatric hepatic angiosarcoma is a rare condition in children with poor prognosis. Microscopically this neoplasm has a particular 'Kaposi-form' arrangement. Hemangiosarcoma in non-human primates is a rare finding. Methods-Gross and microscopic examination of a 3-year-old rhesus were performed. Immunohistochemistry was used to characterize the hepatic hemangiosarcoma. Results-The gross necropsy revealed hemoabdomen and a 4 × 3 × 3 cm mass in the liver with multiple smaller masses throughout the hepatic parenchyma. Histopathology confirmed a poorly differentiated hemangiosarcoma. Other organs submitted were free of metastases. Conclusions-Hemangiosarcoma in non-human primates has been rarely reported. Diagnosis was confirmed by expression of endothelial-specific markers CD31 and vWF by immunohistochemistry. Due to the young age of this monkey and the particular solid pattern throughout the mass this neoplasm resembles pediatric hepatic angiosarcoma in humans.
Fluid Phase Equilibria, 2008
Isobaric vapor–liquid equilibrium (VLE) data have been measured for the ternary system methyl ter... more Isobaric vapor–liquid equilibrium (VLE) data have been measured for the ternary system methyl tert-butyl ether + acetone + cyclohexane, and for its methyl tert-butyl ether based binaries, at 94 kPa and in the temperature ...
Fluid Phase Equilibria, 2008
An approach for specializing cubic equations of state to the prediction of vapor pressures of pur... more An approach for specializing cubic equations of state to the prediction of vapor pressures of pure fluids is presented. The method is based on a low-temperature asymptotic approximation of the vapor–liquid equilibrium problem which, ...
Fluid Phase Equilibria, 2013
ABSTRACT Isobaric vapor–liquid equilibrium (VLE) data have been measured for the binary system he... more ABSTRACT Isobaric vapor–liquid equilibrium (VLE) data have been measured for the binary system hexane + tetrahydro-2H-pyran at 50, 75, and 94 kPa and over the temperature range 321–358 K using a vapor–liquid equilibrium still with circulation of both phases. Atmospheric surface tension data have been also determined at 303.15 K using a maximum bubble pressure tensiometer. Experimental results show that the mixture is zeotropic and exhibits slight positive deviation from ideal behavior over the experimental range. Surface tensions, in turn, exhibit negative deviation from the linear behavior.The VLE data of the binary mixture satisfy the Fredenlund's consistency test and were well-correlated by the Wohl, nonrandom two-liquid (NRTL), Wilson, and universal quasichemical (UNIQUAC) equations. The dependence of surface tensions on mole fraction was satisfactorily smoothed using the Redlich–Kister equation.The experimental VLE and surface tension data were accurately predicted by applying the square gradient theory to the Peng–Robinson Stryjek–Vera equation of state (EoS), appropriately extended to mixtures with a modified Huron–Vidal mixing rule. This theoretical model was also applied to describe the surface activity of species along the interfacial region, from which it was concluded that hexane presents interfacial accumulation and, therefore, a positive relative Gibbs adsorption isotherm on THP.
Fluid Phase Equilibria, 2008
... PDF (952 K); Export citation; E-mail article; Highlight keywords on: No highlighting Reflect ... more ... PDF (952 K); Export citation; E-mail article; Highlight keywords on: No highlighting Reflect Reflect highlight proteins and chemicals NextBio NextBio highlight relevant biomedical terms. Thumbnails - selected | Full-Size images. ...
Energy, 2012
ABSTRACT An accurate description of the geometry of the temperature-entropy (T-S) diagram is of f... more ABSTRACT An accurate description of the geometry of the temperature-entropy (T-S) diagram is of fundamental importance for predicting the state of working fluids undergoing isentropic processes, as usually required for analyzing the performance of refrigeration and power generation systems. In this contri- bution, rigorous analytical expressions have been obtained for the first and second temperature deriv- atives of the entropy envelope along the vaporeliquid equilibrium (VLE) path of pure fluids. These relationships are valid from the triple point up o the critical state, and have been conveniently expressed in terms of Helmholtz’s energy, thus yielding a generalized method able to describe the geometry of the TeS diagram from typical equation of state (EOS) models. The customary classification of fluids in wet, isentropic or dry behavior has been reduced to a simple criterion based on a new dimensionless function j and how its value compares with the value of the isobaric heat capacity of the ideal gas. Applications are presented for cubic models of the van der Waals type, specific multi-parameter equations, molecular- based models, and virial density expansions. From these results it is concluded that dry behavior depends on the number of atoms that compose the molecule, and it will be generally observed in long-chained molecules.
Educational Action Research, 2008
An action research approach called Soft Systems Methodology (SSM) was used to foster organisation... more An action research approach called Soft Systems Methodology (SSM) was used to foster organisational learning in a school regarding the role of the Learning Support department within the school and its relation with the normal teaching-learning activities. From an initial situation of lack of coordination as well as mutual misunderstanding and distrust among some of the actors in the situation, 8 months of work yielded as a result a better working environment among the participants, the creation of a volunteer discussion group functioning on a permanent basis, and a clarification and modification of some of the Learning Support activities. This change can also be described as a learning by Learning Support staff, school teachers and administrators, on how to work together, as well as on how to support children's learning in a better way. Nevertheless, a further change that occurred after the intervention, shows the importance of considering a wider system than that limited by the participants in the intervention.
Cambridge Journal of Education, 2007
This work is based on the assumption that if the classroom is a space in which manifestations of ... more This work is based on the assumption that if the classroom is a space in which manifestations of critical autonomous thinking appear systematically, then it promotes that same kind of thinking by the students, in other contexts. But what count as manifestations ...
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
The ingestion of alcohol has been linked to characteristic changes in EEG activity, and these cha... more The ingestion of alcohol has been linked to characteristic changes in EEG activity, and these changes depend on several factors. Previous research has been conducted with a variety of experimental designed, but most have focused on reporting the effect of alcohol consumption in subjects with a history of alcohol abuse, and a few have reported the effects of lower doses of alcohol. This project recorded brain activity related to attention in a driving situation with an emotiv EPOC brain control interface (BCI) device after ingestion of 0,300 g of alcohol (0,02 % bac) or none in a preexperiemental pre-test and post-test design with 30 college students aged 18-45. Results suggest that lower doses of alcohol change wave dynamics, reducing the amplitude of fast alpha (9-13Hz) and beta (14-30Hz) waves in frontal lobe zones involved in sustained attention in driving.