This work presents a classification of the proper homotopy types of locally finite 1-dimensional ... more This work presents a classification of the proper homotopy types of locally finite 1-dimensional CWcomplexes.
Proceedings of The Edinburgh Mathematical Society, 1989
... Page 12. 412 R. AYALA, E. DOMINGUEZ AND A. QUINTERO (b) Theorem 4.4 with X compact is proved ... more ... Page 12. 412 R. AYALA, E. DOMINGUEZ AND A. QUINTERO (b) Theorem 4.4 with X compact is proved in [7]. (c) For n=0, it is proved in [6] that if X and Y are noncompact T2-locally ff-compact and path-connected then X x Y has only one proper end. ...
The goal of this work is to study the structure of the pure Morse complex of a graph, that is, th... more The goal of this work is to study the structure of the pure Morse complex of a graph, that is, the simplicial complex given by the set of all possible classes of discrete Morse functions (in Forman's sense) defined on it. First, we characterize the pure Morse complex of a tree and prove that it is collapsible. In order to study the general case, we consider all the spanning trees included in a given graph G and we express the pure Morse complex of G as the union of all pure Morse complexes corresponding to such trees.
S. Mazurkiewicz remarked after his proof of the celebrated Hahn-Mazurkiewicz Theorem ([5]) that a... more S. Mazurkiewicz remarked after his proof of the celebrated Hahn-Mazurkiewicz Theorem ([5]) that any generalized Peano continuum is the continuous image of the half-line $[0, \infty)$ but the converse does not hold. Therefore continuous images of $[0, \infty)$ do not characterize generalized Peano continua. In this paper we use perfect maps and trees to obtain an analogue of the Hahn-Mazurkiewicz Theorem for generalized Peano continua in the spirit of the classical Hahn-Mazurkiewicz Theorem.
Mathematical Proceedings of The Cambridge Philosophical Society, 1990
... Page 4. 478 R. AYALA, A. QUINTERO AND E. DOMINGUEZ Let (X, x0) and (T, t0) be pointed spaces ... more ... Page 4. 478 R. AYALA, A. QUINTERO AND E. DOMINGUEZ Let (X, x0) and (T, t0) be pointed spaces with X compact and T T2-locally compact and cr-compact. By X(T) and XC(T) we denote the canonical spaces, under and over T,XxT and X x T/X x {t0}respectively. ...
The present article compares Cantoral and Farfan's socio-epistemological approach to mathematics ... more The present article compares Cantoral and Farfan's socio-epistemological approach to mathematics education research (MER) with approaches of other current constructivist schools (such as emergent and sociocultural constructivism), in which interactionist and realistic approaches blend together. The theoretical problems of all these perspectives seem to center on the role that cultural tools are to play in future discourse of the different approaches to MER and identifying a set of problems with common ground in order to make comparisons possible.
En cada una de las entregas de la revista incluimos un caso, desarrollado por estudiantes, selecc... more En cada una de las entregas de la revista incluimos un caso, desarrollado por estudiantes, seleccionado entre los mejores presentados para evaluación editorial, con el objetivo de brindar una herramienta académica de acercamiento a una situación específica de nuestro contexto.
3Department of Pathology, University of Pittsburgh, PA. Signal Transducers and Activators of Tran... more 3Department of Pathology, University of Pittsburgh, PA. Signal Transducers and Activators of Transcription (STAT) are a family of transcription factors that are activated through phosphorylation either by receptor tyrosine kinases or janus kinases (JAK). Upon activation they translocate to the nucleus and change the transcription of several genes. In long term (up to 36 days) serum-flee primary cultures of human hepatocytes we found association of c-MET (receptor of Hepatocyte Growth Factor, HGF) and Epidermal Growth Factor (EGF)receptor (F_,GFR) with STAT 1, STAT 3, and STAT 5. Short term (1-15 min) induction experiments with HGF and EGF revealed that each of the two growth factors induced association of STAT 3 with c-MET and EGFR, but at different time points. Neutralizing antibodies against HGF or EGF reduced or prevented the association of STAT 3 with c-MET indicating a specific role of the growth factors in STAT 3 activation. STAT 5 was activated namely phosphorylated only by EGF, neither HGF nor HGF plus EGF. STAT 3 was associated with JAK-2 after stimulation with HGF, but not EGF. This association correlated with maximum DNA-binding activity, indicating a role of JAK-2 in maximal activation of STAT 3 by HGF.
Prostaglandin E 1 (PGE 1 ) reduces cell death in experimental and clinical manifestations of live... more Prostaglandin E 1 (PGE 1 ) reduces cell death in experimental and clinical manifestations of liver dysfunction. Nitric oxide (NO) has been shown to exert a protective or noxious effect in different experimental models of liver injury. The aim of the present study was to investigate the role of NO during PGE 1 protection against D D -galactosamine (D D -GalN) citotoxicity in cultured hepatocytes. PGE 1 was preadministered to D D -GalN-treated hepatocytes. The role of NO in our system was assessed by iNOS inhibition and a NO donor. Different parameters related to apoptosis and necrosis, NO production such as nitrite+nitrate (NO x ) release, iNOS expression, and NF-jB activation in hepatocytes were evaluated. The inhibition of iNOS reduced apoptosis induced by D D -GalN in hepatocytes. PGE 1 protection against D D -GalN injury was associated with its capacity to reduce iNOS expression and NO production induced by D D -GalN. Nevertheless, iNOS inhibition showed that protection by PGE 1 was also mediated by NO. Low concentrations of a NO donor reduced D D -GalN injury with a decrease in the extracellular NO x concentration. High concentrations of the NO donor enhanced NO x concentration and increased cell death by D D -GalN. The present study suggests that low NO production induced by PGE 1 preadministration reduces D D -GalN-induced cell death through its capacity to reduce iNOS expression and NO production caused by the hepatotoxin.
Entendida como el desarrollo -de capacidades para dirigir y conducir el rumbo de la empresa hacia... more Entendida como el desarrollo -de capacidades para dirigir y conducir el rumbo de la empresa hacia el logro de sus propios objetivos; para que la cooperativa funcione plenamente con eficacia y eficiencia, se divide en 5 áreas y un sistema operativo que la integran.
This work presents a classification of the proper homotopy types of locally finite 1-dimensional ... more This work presents a classification of the proper homotopy types of locally finite 1-dimensional CWcomplexes.
Proceedings of The Edinburgh Mathematical Society, 1989
... Page 12. 412 R. AYALA, E. DOMINGUEZ AND A. QUINTERO (b) Theorem 4.4 with X compact is proved ... more ... Page 12. 412 R. AYALA, E. DOMINGUEZ AND A. QUINTERO (b) Theorem 4.4 with X compact is proved in [7]. (c) For n=0, it is proved in [6] that if X and Y are noncompact T2-locally ff-compact and path-connected then X x Y has only one proper end. ...
The goal of this work is to study the structure of the pure Morse complex of a graph, that is, th... more The goal of this work is to study the structure of the pure Morse complex of a graph, that is, the simplicial complex given by the set of all possible classes of discrete Morse functions (in Forman's sense) defined on it. First, we characterize the pure Morse complex of a tree and prove that it is collapsible. In order to study the general case, we consider all the spanning trees included in a given graph G and we express the pure Morse complex of G as the union of all pure Morse complexes corresponding to such trees.
S. Mazurkiewicz remarked after his proof of the celebrated Hahn-Mazurkiewicz Theorem ([5]) that a... more S. Mazurkiewicz remarked after his proof of the celebrated Hahn-Mazurkiewicz Theorem ([5]) that any generalized Peano continuum is the continuous image of the half-line $[0, \infty)$ but the converse does not hold. Therefore continuous images of $[0, \infty)$ do not characterize generalized Peano continua. In this paper we use perfect maps and trees to obtain an analogue of the Hahn-Mazurkiewicz Theorem for generalized Peano continua in the spirit of the classical Hahn-Mazurkiewicz Theorem.
Mathematical Proceedings of The Cambridge Philosophical Society, 1990
... Page 4. 478 R. AYALA, A. QUINTERO AND E. DOMINGUEZ Let (X, x0) and (T, t0) be pointed spaces ... more ... Page 4. 478 R. AYALA, A. QUINTERO AND E. DOMINGUEZ Let (X, x0) and (T, t0) be pointed spaces with X compact and T T2-locally compact and cr-compact. By X(T) and XC(T) we denote the canonical spaces, under and over T,XxT and X x T/X x {t0}respectively. ...
The present article compares Cantoral and Farfan's socio-epistemological approach to mathematics ... more The present article compares Cantoral and Farfan's socio-epistemological approach to mathematics education research (MER) with approaches of other current constructivist schools (such as emergent and sociocultural constructivism), in which interactionist and realistic approaches blend together. The theoretical problems of all these perspectives seem to center on the role that cultural tools are to play in future discourse of the different approaches to MER and identifying a set of problems with common ground in order to make comparisons possible.
En cada una de las entregas de la revista incluimos un caso, desarrollado por estudiantes, selecc... more En cada una de las entregas de la revista incluimos un caso, desarrollado por estudiantes, seleccionado entre los mejores presentados para evaluación editorial, con el objetivo de brindar una herramienta académica de acercamiento a una situación específica de nuestro contexto.
3Department of Pathology, University of Pittsburgh, PA. Signal Transducers and Activators of Tran... more 3Department of Pathology, University of Pittsburgh, PA. Signal Transducers and Activators of Transcription (STAT) are a family of transcription factors that are activated through phosphorylation either by receptor tyrosine kinases or janus kinases (JAK). Upon activation they translocate to the nucleus and change the transcription of several genes. In long term (up to 36 days) serum-flee primary cultures of human hepatocytes we found association of c-MET (receptor of Hepatocyte Growth Factor, HGF) and Epidermal Growth Factor (EGF)receptor (F_,GFR) with STAT 1, STAT 3, and STAT 5. Short term (1-15 min) induction experiments with HGF and EGF revealed that each of the two growth factors induced association of STAT 3 with c-MET and EGFR, but at different time points. Neutralizing antibodies against HGF or EGF reduced or prevented the association of STAT 3 with c-MET indicating a specific role of the growth factors in STAT 3 activation. STAT 5 was activated namely phosphorylated only by EGF, neither HGF nor HGF plus EGF. STAT 3 was associated with JAK-2 after stimulation with HGF, but not EGF. This association correlated with maximum DNA-binding activity, indicating a role of JAK-2 in maximal activation of STAT 3 by HGF.
Prostaglandin E 1 (PGE 1 ) reduces cell death in experimental and clinical manifestations of live... more Prostaglandin E 1 (PGE 1 ) reduces cell death in experimental and clinical manifestations of liver dysfunction. Nitric oxide (NO) has been shown to exert a protective or noxious effect in different experimental models of liver injury. The aim of the present study was to investigate the role of NO during PGE 1 protection against D D -galactosamine (D D -GalN) citotoxicity in cultured hepatocytes. PGE 1 was preadministered to D D -GalN-treated hepatocytes. The role of NO in our system was assessed by iNOS inhibition and a NO donor. Different parameters related to apoptosis and necrosis, NO production such as nitrite+nitrate (NO x ) release, iNOS expression, and NF-jB activation in hepatocytes were evaluated. The inhibition of iNOS reduced apoptosis induced by D D -GalN in hepatocytes. PGE 1 protection against D D -GalN injury was associated with its capacity to reduce iNOS expression and NO production induced by D D -GalN. Nevertheless, iNOS inhibition showed that protection by PGE 1 was also mediated by NO. Low concentrations of a NO donor reduced D D -GalN injury with a decrease in the extracellular NO x concentration. High concentrations of the NO donor enhanced NO x concentration and increased cell death by D D -GalN. The present study suggests that low NO production induced by PGE 1 preadministration reduces D D -GalN-induced cell death through its capacity to reduce iNOS expression and NO production caused by the hepatotoxin.
Entendida como el desarrollo -de capacidades para dirigir y conducir el rumbo de la empresa hacia... more Entendida como el desarrollo -de capacidades para dirigir y conducir el rumbo de la empresa hacia el logro de sus propios objetivos; para que la cooperativa funcione plenamente con eficacia y eficiencia, se divide en 5 áreas y un sistema operativo que la integran.
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