Nestor Ortega - Academia.edu (original) (raw)
Papers by Nestor Ortega
This paper deals with the validation of an EMI model to predict electromagnetic interferences (EM... more This paper deals with the validation of an EMI model to predict electromagnetic interferences (EMI) produced by power converters. A direct AC to AC matrix converter (MC) has been selected as experimental setup for the paper, but the modeling method can be applied to other converter topologies.
Journal of Organometallic Chemistry, 2004
In recent years, Fe(0) complexes have received much attraction owing to their structural diversit... more In recent years, Fe(0) complexes have received much attraction owing to their structural diversity and widespread application in organic and organometallic chemistry. Among these interesting compounds especial attention has been aimed to the study of Fe(0) vinylketone ...
Molecular and Biochemical Parasitology, 2005
Journal of Natural Products, 1992
The presence of viruses (myxomatosis and haemorrhagic fever), helminth parasites and coccidia wer... more The presence of viruses (myxomatosis and haemorrhagic fever), helminth parasites and coccidia were studied in European wild rabbit (Oryctolagus cuniculus) introduced from the Iberian Peninsula to Tenerife Island (Canary Islands). Rabbits were captured between 1998 and 2000 in four geographic zones in Tenerife Island. Blood samples were taken from rabbits before dissection and faeces were obtained from the rectum of the individuals for the purposes of the protozoological study. In sera samples, Elisa test was carried out to detect antibodies for myxomatosis and haemorrhagic fever. Helminths were removed from the digestive tract and sporulated coccidia were obtained in potassium dichromate. Significant differences in the prevalence of the myxomatosis between years, seasons and zones were found. In all zones, there were no statistically significant differences between rabbits infected with haemorrhagic fever. Furthermore, no significant differences in prevalence between years and seasons were observed for the haemorrhagic fever. Five helminth species were found: Taenia pisiformis (larvae), Mosgovoyia ctenoides, Andrya cuniculi, Trichostrongylus retortaeformis and Passalurus ambiguus. No significant seasonal differences in the prevalence for any helminth species were detected. There were significant differences for the mean intensities of T. retortaeformis between the spring and the autumn 1999 and between the autumn and the winter 1999. Seasonal significant differences in the prevalence for Eimeria spp. were detected. A significant correlation between the myxomatosis and the mean intensity of T. pisiformis was found. Haemorrhagic fever and coccidian prevalence showed no significant relationship. The obtained results on parasites (viruses, coccidia and helminths) relationship in different zones, years and seasons are discussed in light of their transmission in Tenerife Island.
The intention of the author for writing this article is to consider the thinking since the person... more The intention of the author for writing this article is to consider the thinking since the personally point of view and talking into account the logical dialec- tically formal logical, cybernetic and psychologically approach trough the development of the epistemologically on the conditions of the teaching proc- ess, in which the students appear as an active subject in the consequence
Cardiovascular Revascularization Medicine, 2005
Based on our preclinic studies with autologous unfractionated bone marrow (AUBM) via coronary sin... more Based on our preclinic studies with autologous unfractionated bone marrow (AUBM) via coronary sinus with transitory occlusion, a clinic study in patients with chronic refractory angina was designed. The objectives were to evaluate tolerance of the procedure, safety, and feasibility with 1 year follow-up. Clinical study with inclusion and exclusion criteria defined by an Independent Clinical Committee was carried out. Fifteen patients underwent transcoronary sinus administration with a 15-min occlusion of freshly aspirated and filtered AUBM (60-120 ml). Feasibility was evaluated with Seattle Angina Questionnaire (SAQ), Canadian Cardiovascular Society (CCS) angina classification, perfusion dipyridamole, and coronary angiography. There were no changes in the tolerance parameters. There were no deaths or myocardial infarction during the follow-up. Three patients were readmitted into the hospital. During the follow-up, one patient was diagnosed with cancer of the lung. Improvement of 30% in the quality of life was evaluated by SAQ. The CCS angina classification showed that the mean angina class was 3.0+/-0.53 at baseline, which improved to 1.6+/-0.63 at 1 year (P<.001). Perfusion imaging (core lab) showed improvement in 12 of 15 patients, with a mean improvement of 40.9% at rest (22 vs. 13) (P<.01) and 45.3% at stress (26.5 vs. 14.5) (P<.05). Coronary angiography showed more collateral vessels in 10 of 15 patients. We can conclude that AUBM via coronary sinus is feasible in patients with chronic refractory angina after 1 year follow-up, and it appears to be safe.
Building and Environment, 2006
Current Microbiology, 2003
In the present study, we demonstrated the Random Amplified Polymorphism DNA (RAPD) diagnostic val... more In the present study, we demonstrated the Random Amplified Polymorphism DNA (RAPD) diagnostic validity. In our study, we have analyzed RAPD profiles searching for characteristic and useful bands for Acanthamoeba diagnosis at the species level. We found a distinctive 370-bp band in A. divionensis RAPD patterns, using the OPC14 primer (TGCGTGCTTG) (Operon Technologies, Inc., Alameda, CA). The band specificity was confirmed by hybridization, using it as a probe, against all OPC14 amplifications from 10 different Acanthamoeba species. Once we sequenced this band, we used it to design a specific primer pair which showed positive amplification only in A. divionensis isolates. RID=”” ID=”” Correspondence to: A. Ortega-Rivas; email: aortega@ull.es
Experimental Parasitology, 2007
Intestinal helminths and blood protozoa are common parasites of lizards. In captivity they can be... more Intestinal helminths and blood protozoa are common parasites of lizards. In captivity they can be a serious problem, but no information on treatments is available. In this study, several antiparasitic drugs were studied in Gallotia caesaris (Lacertida) from La Gomera, the Canary Islands, Spain. A lack of efficacy of chloroquine, and a decrease in haemogregarine (Apicomplexa) infection by atovaquoneproguanil was demonstrated. Furthermore, a positive effect of fenbendazole against intestinal nematode infection was observed. In the Canary Islands, Gallotia bravoana and Gallotia simonyi (Lacertida) are included in a captive breading recovery plan. The present results are useful in order to keep these animals in good condition and to control their parasites. Moreover, these results are important for reptiles kept as pets, due to the previous lack of knowledge of parasite management.
Experimental Techniques, 1997
La viga es el elemento estructural utilizado para cubrir espacios, soportando el peso colocado en... more La viga es el elemento estructural utilizado para cubrir espacios, soportando el peso colocado encima del elemento mediante la resistencia a las fuerzas internas de flexión y corte.
Informes De La Construccion, 2006
Optical Materials, 2005
a-and c-(Al 1Àx Eu x ) 2 O 3 polycrystalline phosphor powders have been prepared via pressure ass... more a-and c-(Al 1Àx Eu x ) 2 O 3 polycrystalline phosphor powders have been prepared via pressure assisted combustion synthesis at $280°C. The particle size could be controlled (nanoparticles/microparticles) by adjusting the initial pressure in the combustion reactor. Upon excitation at 394 nm, the Eu-doped alumina nanoparticles exhibited a strong photoluminescence due to a parity forbidden f-f intraconfigurational transition upon excitation at k = 395 nm. By analyzing the emission lines in the cathodoluminescence spectrum of the europium doped a-Al 2 O 3 sample it was inferred that the dopant ions occupy low symmetry sites in the host lattice. These powders are potentially good candidates for photonics applications.
Strain, 1998
Strain gauge application has been used to study the mechanical behaviour of shell models. Applica... more Strain gauge application has been used to study the mechanical behaviour of shell models. Application has been made directly to acrylic devices designed by means of the homeostatic model technique. The testing procedure of one such model made with the aim of assessing the anticipated membrane status is detailed. This has resulted in an interesting experience of strain gauge application to this type of material.
Construction and Building Materials, 2011
This paper shows the results of a laboratory experimental study, characterizing cracking on concr... more This paper shows the results of a laboratory experimental study, characterizing cracking on concrete beams produced by corrosion of steel reinforcement exposed to different atmospheres. These environmental conditions were obtained by means of two electrolytic media: one alkaline, simulating the situation that occurs in an industrial environment, with beams exposed to a saturated solution of Calcium Hydroxide; and another with
Phytotherapy Research, 1999
Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous c... more Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous crude extract suffer a hypotonic-like effect. The phenomena exhibited included a distension of the plasma membrane over the acrosome region, inducing the formation of a huge 'head-bubble'. The agglutination effect was so enhanced that instead of inducing sperm clusters, it produced cane-like 'stalk' structures. The immobilizing activity was induced instantaneously after the addition of the purified fraction. At electron microscope level it was possible to observe a heavy amount of electron dense material of the purified fraction embedded or intercalated along the plasma membrane. It was also possible to corroborate the dispersion of the acrosomal content and the disappearance of the external acrosome membrane. The purified fraction induced loosening of the plasma membrane all along the sperm cell, however, the distension of the membrane was only produced in the apical portion of the sperm head and not in the post equatorial region. The results suggest that the plant may yield a compound suitable for use as a vaginal barrier or male contraceptive agent. #
The Open Construction and Building Technology Journal, 2008
Phytotherapy Research, 1999
Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous c... more Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous crude extract suffer a hypotonic-like effect. The phenomena exhibited included a distension of the plasma membrane over the acrosome region, inducing the formation of a huge 'head-bubble'. The agglutination effect was so enhanced that instead of inducing sperm clusters, it produced cane-like 'stalk' structures. The immobilizing activity was induced instantaneously after the addition of the purified fraction. At electron microscope level it was possible to observe a heavy amount of electron dense material of the purified fraction embedded or intercalated along the plasma membrane. It was also possible to corroborate the dispersion of the acrosomal content and the disappearance of the external acrosome membrane. The purified fraction induced loosening of the plasma membrane all along the sperm cell, however, the distension of the membrane was only produced in the apical portion of the sperm head and not in the post equatorial region. The results suggest that the plant may yield a compound suitable for use as a vaginal barrier or male contraceptive agent. #
This paper deals with the validation of an EMI model to predict electromagnetic interferences (EM... more This paper deals with the validation of an EMI model to predict electromagnetic interferences (EMI) produced by power converters. A direct AC to AC matrix converter (MC) has been selected as experimental setup for the paper, but the modeling method can be applied to other converter topologies.
Journal of Organometallic Chemistry, 2004
In recent years, Fe(0) complexes have received much attraction owing to their structural diversit... more In recent years, Fe(0) complexes have received much attraction owing to their structural diversity and widespread application in organic and organometallic chemistry. Among these interesting compounds especial attention has been aimed to the study of Fe(0) vinylketone ...
Molecular and Biochemical Parasitology, 2005
Journal of Natural Products, 1992
The presence of viruses (myxomatosis and haemorrhagic fever), helminth parasites and coccidia wer... more The presence of viruses (myxomatosis and haemorrhagic fever), helminth parasites and coccidia were studied in European wild rabbit (Oryctolagus cuniculus) introduced from the Iberian Peninsula to Tenerife Island (Canary Islands). Rabbits were captured between 1998 and 2000 in four geographic zones in Tenerife Island. Blood samples were taken from rabbits before dissection and faeces were obtained from the rectum of the individuals for the purposes of the protozoological study. In sera samples, Elisa test was carried out to detect antibodies for myxomatosis and haemorrhagic fever. Helminths were removed from the digestive tract and sporulated coccidia were obtained in potassium dichromate. Significant differences in the prevalence of the myxomatosis between years, seasons and zones were found. In all zones, there were no statistically significant differences between rabbits infected with haemorrhagic fever. Furthermore, no significant differences in prevalence between years and seasons were observed for the haemorrhagic fever. Five helminth species were found: Taenia pisiformis (larvae), Mosgovoyia ctenoides, Andrya cuniculi, Trichostrongylus retortaeformis and Passalurus ambiguus. No significant seasonal differences in the prevalence for any helminth species were detected. There were significant differences for the mean intensities of T. retortaeformis between the spring and the autumn 1999 and between the autumn and the winter 1999. Seasonal significant differences in the prevalence for Eimeria spp. were detected. A significant correlation between the myxomatosis and the mean intensity of T. pisiformis was found. Haemorrhagic fever and coccidian prevalence showed no significant relationship. The obtained results on parasites (viruses, coccidia and helminths) relationship in different zones, years and seasons are discussed in light of their transmission in Tenerife Island.
The intention of the author for writing this article is to consider the thinking since the person... more The intention of the author for writing this article is to consider the thinking since the personally point of view and talking into account the logical dialec- tically formal logical, cybernetic and psychologically approach trough the development of the epistemologically on the conditions of the teaching proc- ess, in which the students appear as an active subject in the consequence
Cardiovascular Revascularization Medicine, 2005
Based on our preclinic studies with autologous unfractionated bone marrow (AUBM) via coronary sin... more Based on our preclinic studies with autologous unfractionated bone marrow (AUBM) via coronary sinus with transitory occlusion, a clinic study in patients with chronic refractory angina was designed. The objectives were to evaluate tolerance of the procedure, safety, and feasibility with 1 year follow-up. Clinical study with inclusion and exclusion criteria defined by an Independent Clinical Committee was carried out. Fifteen patients underwent transcoronary sinus administration with a 15-min occlusion of freshly aspirated and filtered AUBM (60-120 ml). Feasibility was evaluated with Seattle Angina Questionnaire (SAQ), Canadian Cardiovascular Society (CCS) angina classification, perfusion dipyridamole, and coronary angiography. There were no changes in the tolerance parameters. There were no deaths or myocardial infarction during the follow-up. Three patients were readmitted into the hospital. During the follow-up, one patient was diagnosed with cancer of the lung. Improvement of 30% in the quality of life was evaluated by SAQ. The CCS angina classification showed that the mean angina class was 3.0+/-0.53 at baseline, which improved to 1.6+/-0.63 at 1 year (P<.001). Perfusion imaging (core lab) showed improvement in 12 of 15 patients, with a mean improvement of 40.9% at rest (22 vs. 13) (P<.01) and 45.3% at stress (26.5 vs. 14.5) (P<.05). Coronary angiography showed more collateral vessels in 10 of 15 patients. We can conclude that AUBM via coronary sinus is feasible in patients with chronic refractory angina after 1 year follow-up, and it appears to be safe.
Building and Environment, 2006
Current Microbiology, 2003
In the present study, we demonstrated the Random Amplified Polymorphism DNA (RAPD) diagnostic val... more In the present study, we demonstrated the Random Amplified Polymorphism DNA (RAPD) diagnostic validity. In our study, we have analyzed RAPD profiles searching for characteristic and useful bands for Acanthamoeba diagnosis at the species level. We found a distinctive 370-bp band in A. divionensis RAPD patterns, using the OPC14 primer (TGCGTGCTTG) (Operon Technologies, Inc., Alameda, CA). The band specificity was confirmed by hybridization, using it as a probe, against all OPC14 amplifications from 10 different Acanthamoeba species. Once we sequenced this band, we used it to design a specific primer pair which showed positive amplification only in A. divionensis isolates. RID=”” ID=”” Correspondence to: A. Ortega-Rivas; email: aortega@ull.es
Experimental Parasitology, 2007
Intestinal helminths and blood protozoa are common parasites of lizards. In captivity they can be... more Intestinal helminths and blood protozoa are common parasites of lizards. In captivity they can be a serious problem, but no information on treatments is available. In this study, several antiparasitic drugs were studied in Gallotia caesaris (Lacertida) from La Gomera, the Canary Islands, Spain. A lack of efficacy of chloroquine, and a decrease in haemogregarine (Apicomplexa) infection by atovaquoneproguanil was demonstrated. Furthermore, a positive effect of fenbendazole against intestinal nematode infection was observed. In the Canary Islands, Gallotia bravoana and Gallotia simonyi (Lacertida) are included in a captive breading recovery plan. The present results are useful in order to keep these animals in good condition and to control their parasites. Moreover, these results are important for reptiles kept as pets, due to the previous lack of knowledge of parasite management.
Experimental Techniques, 1997
La viga es el elemento estructural utilizado para cubrir espacios, soportando el peso colocado en... more La viga es el elemento estructural utilizado para cubrir espacios, soportando el peso colocado encima del elemento mediante la resistencia a las fuerzas internas de flexión y corte.
Informes De La Construccion, 2006
Optical Materials, 2005
a-and c-(Al 1Àx Eu x ) 2 O 3 polycrystalline phosphor powders have been prepared via pressure ass... more a-and c-(Al 1Àx Eu x ) 2 O 3 polycrystalline phosphor powders have been prepared via pressure assisted combustion synthesis at $280°C. The particle size could be controlled (nanoparticles/microparticles) by adjusting the initial pressure in the combustion reactor. Upon excitation at 394 nm, the Eu-doped alumina nanoparticles exhibited a strong photoluminescence due to a parity forbidden f-f intraconfigurational transition upon excitation at k = 395 nm. By analyzing the emission lines in the cathodoluminescence spectrum of the europium doped a-Al 2 O 3 sample it was inferred that the dopant ions occupy low symmetry sites in the host lattice. These powders are potentially good candidates for photonics applications.
Strain, 1998
Strain gauge application has been used to study the mechanical behaviour of shell models. Applica... more Strain gauge application has been used to study the mechanical behaviour of shell models. Application has been made directly to acrylic devices designed by means of the homeostatic model technique. The testing procedure of one such model made with the aim of assessing the anticipated membrane status is detailed. This has resulted in an interesting experience of strain gauge application to this type of material.
Construction and Building Materials, 2011
This paper shows the results of a laboratory experimental study, characterizing cracking on concr... more This paper shows the results of a laboratory experimental study, characterizing cracking on concrete beams produced by corrosion of steel reinforcement exposed to different atmospheres. These environmental conditions were obtained by means of two electrolytic media: one alkaline, simulating the situation that occurs in an industrial environment, with beams exposed to a saturated solution of Calcium Hydroxide; and another with
Phytotherapy Research, 1999
Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous c... more Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous crude extract suffer a hypotonic-like effect. The phenomena exhibited included a distension of the plasma membrane over the acrosome region, inducing the formation of a huge 'head-bubble'. The agglutination effect was so enhanced that instead of inducing sperm clusters, it produced cane-like 'stalk' structures. The immobilizing activity was induced instantaneously after the addition of the purified fraction. At electron microscope level it was possible to observe a heavy amount of electron dense material of the purified fraction embedded or intercalated along the plasma membrane. It was also possible to corroborate the dispersion of the acrosomal content and the disappearance of the external acrosome membrane. The purified fraction induced loosening of the plasma membrane all along the sperm cell, however, the distension of the membrane was only produced in the apical portion of the sperm head and not in the post equatorial region. The results suggest that the plant may yield a compound suitable for use as a vaginal barrier or male contraceptive agent. #
The Open Construction and Building Technology Journal, 2008
Phytotherapy Research, 1999
Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous c... more Guinea-pig spermatozoa in the presence of a purified fraction from Echeveria gibbiflora aqueous crude extract suffer a hypotonic-like effect. The phenomena exhibited included a distension of the plasma membrane over the acrosome region, inducing the formation of a huge 'head-bubble'. The agglutination effect was so enhanced that instead of inducing sperm clusters, it produced cane-like 'stalk' structures. The immobilizing activity was induced instantaneously after the addition of the purified fraction. At electron microscope level it was possible to observe a heavy amount of electron dense material of the purified fraction embedded or intercalated along the plasma membrane. It was also possible to corroborate the dispersion of the acrosomal content and the disappearance of the external acrosome membrane. The purified fraction induced loosening of the plasma membrane all along the sperm cell, however, the distension of the membrane was only produced in the apical portion of the sperm head and not in the post equatorial region. The results suggest that the plant may yield a compound suitable for use as a vaginal barrier or male contraceptive agent. #