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1.
Environ Entomol ; 52(3): 341-349, 2023 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-37043621

RESUMEN

Ecosystem loss and degradation has become a worldwide concern. The implementation of ecological restoration plans has been proposed to facilitate the recovery of ecosystems. It is imperative that once restoration strategies have been implemented, the effects of these actions in the medium and long term be evaluated, particularly the structure and functioning of the ecosystem. Diversity (α- and ß-diversity) of beetles attracted to dung was assessed and compared in 3 habitat conditions (conserved forest, passive restoration, and active restoration) at 2 different seasons during the year (dry vs. rainy season) in cloud forest in San Luis Potosí (central Mexico). We found that the dry season was slightly richer than the rainy season, but the latter was significantly more diverse. Species diversity and composition in active restoration were more similar to passive restoration, and both differed greatly from the conserved forest. In contrast, conserved and passive restoration conditions exhibited similar patterns in ß-diversity of insects likely because they maintain more species associated with the original vegetation of the cloud forest. Beetle assemblages could be of more habitat generalists, as they actively distribute across the restoration sites. Beetles attracted to dung provide an overview of the effect of restoration in early faunal recovery, even though we monitored this entomofauna for a short period (31 months after the restoration plots were established). These beetles can be a useful indicator for exploring the main forces driving species diversity for the management and conservation status of cloud forests, a threatened ecosystem.


Asunto(s)
Escarabajos , Ecosistema , Animales , Biodiversidad , Bosques , Estaciones del Año
2.
PLoS One ; 18(1): e0278388, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36634073

RESUMEN

Given the ever-increasing prevalence of type 2 diabetes and obesity, the pressure on global healthcare is expected to be colossal, especially in terms of blindness. Electroretinogram (ERG) has long been perceived as a first-use technique for diagnosing eye diseases, and some studies suggested its use for preventable risk factors of type 2 diabetes and thereby diabetic retinopathy (DR). Here, we show that in a non-evoked mode, ERG signals contain spontaneous oscillations that predict disease cases in rodent models of obesity and in people with overweight, obesity, and metabolic syndrome but not yet diabetes, using one single random forest-based model. Classification performance was both internally and externally validated, and correlation analysis showed that the spontaneous oscillations of the non-evoked ERG are altered before oscillatory potentials, which are the current gold-standard for early DR. Principal component and discriminant analysis suggested that the slow frequency (0.4-0.7 Hz) components are the main discriminators for our predictive model. In addition, we established that the optimal conditions to record these informative signals, are 5-minute duration recordings under daylight conditions, using any ERG sensors, including ones working with portative, non-mydriatic devices. Our study provides an early warning system with promising applications for prevention, monitoring and even the development of new therapies against type 2 diabetes.


Asunto(s)
Diabetes Mellitus Tipo 2 , Retinopatía Diabética , Humanos , Diabetes Mellitus Tipo 2/diagnóstico , Electrorretinografía/métodos , Factores de Riesgo , Retinopatía Diabética/diagnóstico , Retinopatía Diabética/prevención & control , Obesidad
3.
J Environ Manage ; 329: 117038, 2023 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-36528941

RESUMEN

The long-term success of forest restoration programs can be improved using climate-based species distribution models (SDMs) to predict which tree species will tolerate climate change. However, as SDMs cannot estimate if species will recruit at these habitats, determining whether their predictions apply to early life-cycle stages of trees is critical to support such a usage. For this, we propose sowing seeds of the focal tree species under the current climate and simulated climate change conditions in target restoration sites. Thus, using of SDMs to design climate-adaptive forest restoration programs would be supported if the differences in habitat occupancy probabilities of species they predict between the current and future climate concurs with the observed differences in recruitment rates of species when sowed under the current climate and simulated climate change conditions. To test this hypothesis, we calibrated SDMs for Vachellia pennatula and Prosopis laevigata, two pioneer tree species widely recommended to restore human-degraded drylands in Mexico, and transferred them to climate change scenarios. After that, we applied the experimental approach proposed above to validate the predictions of SDMs. These models predicted that V. pennatula will decrease its habitat occupancy probabilities across Mexico, while P. laevigata was predicted to keep out their current habitat occupancy probabilities, or even increase them, in climate change scenarios. The results of the field experiment supported these predictions, as recruitment rates of V. pennatula were lower under simulated climate change than under the current climate, while no differences were found for the recruitment rates of P. laevigata between these environmental conditions. These findings demonstrate that SDMs provide meaningful insights for designing climate-adaptive forest restoration programs but, before applying this methodology, predictions of these models must be validated with field experiments to determine whether the focal tree species will recruit under climate change conditions. Moreover, as the pioneer trees used to test our proposal seem to be differentially sensitive to climate change, this approach also allows establishing what species must be prescribed to restore forests with a view to the future and what species must be avoided in these practices.


Asunto(s)
Cambio Climático , Bosques , Árboles , Humanos , Ecosistema , Predicción , México
4.
J Plant Res ; 135(3): 453-463, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35226225

RESUMEN

Most tree species native to arid and semiarid ecosystems produce seeds with physical dormancy, which have impermeable coats that protect them from desiccation and prevent germination when the environmental conditions are unfavorable for seedling establishment. This dormancy mechanism may confer some degree of tolerance to seeds facing warmer and drier conditions, as those expected in several regions of the world because of climate change. Scarification of these seeds (removal of protective coats) is required for stimulating germination and seedling development. However, as scarification exposes seeds to the external environmental conditions, it can promote desiccation and viability loss in the future. To test these hypotheses, we performed field experiments and sowed scarified and unscarified seeds of a pioneer tree native to semiarid ecosystems of Mesoamerica (Vachellia pennatula) under the current climate and simulated climate change conditions. The experiments were conducted at abandoned fields using open-top chambers to increase temperature and rainout shelters to reduce rainfall. We measured microenvironmental conditions within the experimental plots and monitored seedling emergence and survival during a year. Air temperature and rainfall in climate change simulations approached the values expected for the period 2041-2080. Seedling emergence rates under these climatic conditions were lower than under the current climate. Nevertheless, emergence rates in climate change simulations were even lower for scarified than for unscarified seeds, while the converse occurred under the current climate. On the other hand, although survival rates in climate change simulations were lower than under the current climate, no effects of the scarification treatment were found. In this way, our study suggests that climate change will impair the recruitment of pioneer trees in semiarid environments, even if they produce seeds with physical dormancy, but also indicates that these negative effects will be stronger if seeds are scarified.


Asunto(s)
Cambio Climático , Fabaceae , Ecosistema , Germinación , México , Plantones , Semillas , Árboles
5.
Synthese ; 199(5-6): 11821-11845, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34334829

RESUMEN

In this paper we show that, when analyzed with contemporary tools in logic-such as Dunn-style semantics, Reichenbach's three-valued logic exhibits many interesting features, and even new responses to some of the old objections to it can be attempted. Also, we establish some connections between Reichenbach's three-valued logic and some contra-classical logics.

6.
Sci Total Environ ; 777: 146007, 2021 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-33684753

RESUMEN

The regeneration niche concept states that plant species only occur in habitats where the environmental conditions allow their recruitment. This study focuses on this concept and proposes a novel approach for modelling and experimentally validating the distribution of suitable habitats for the recruitment of invasive plants under the current and future climate. The biological invasion of the Peruvian peppertree (Schinus molle) in Mexico is used as practical example. The values of eight bioclimatic variables associated to sites in which young, naturally established seedlings and saplings were detected were used to model the current distribution of recruitment habitats. A machine-learning algorithm of maximum entropy (MaxEnt) was used to calibrate the model and its output indicated the distribution of occurrence probabilities of young peppertrees in Mexico under the current climate. This model was projected on climate change scenarios predicted for the middle of this century, which indicated that the cover of suitable recruitment habitats for this invasive species will shrink. To validate these predictions, field experiments were performed at three sites where the model predicted reduced occurrence probabilities of young peppertrees. In these experiments, emergence and survival rates of peppertree seedlings were assessed under the current climate and under simulated climate change conditions. As seedling emergence and survival rates were lower under simulated climate change conditions, the experiments validated the model predictions. These results supported our proposal, which combines modelling and experimental approaches to make accurate and valid predictions about the distribution of suitable recruitment habitats for invasive plants in a warmer and drier world.


Asunto(s)
Cambio Climático , Ecosistema , Entropía , Especies Introducidas , México
7.
Methods Mol Biol ; 2174: 277-297, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-32813257

RESUMEN

Stiffness control of cell culture platforms provides researchers in cell biology with the ability to study different experimental models in conditions of mimicking physiological or pathological microenvironments. Nevertheless, the signal transduction pathways and drug sensibility of cancer cells have been poorly characterized widely using biomimetic platforms because the limited experience of cancer cell biology groups about handling substrates with specific mechanical properties. The protein cross-linking and stiffening control are crucial checkpoints that could strongly affect cell adhesion and spreading, misrepresenting the data acquired, and also generating inaccurate cellular models. Here, we introduce a simple method to adhere to polyacrylamide (PAA) hydrogels on glass coverslips without any special treatment for mechanics studies in cancer cell biology. By using a commercial photosensitive glue, Loctite 3525, it is possible to polymerize PAA hydrogels directly on glass surfaces. Furthermore, we describe a cross-linking reaction method to attach proteins to PAA as an alternative method to Sulfo-SANPAH cross-linking, which is sometimes difficult to implement and reproduce. In this chapter, we describe a reliable procedure to fabricate ECM protein-cross-linked PAA hydrogels for mechanotransduction studies on cancer cells.


Asunto(s)
Resinas Acrílicas/química , Adhesivos/química , Adhesión Celular , Hidrogeles/química , Neoplasias/patología , Reactivos de Enlaces Cruzados/química , Matriz Extracelular/metabolismo , Matriz Extracelular/patología , Proteínas de la Matriz Extracelular/química , Técnica del Anticuerpo Fluorescente , Vidrio , Células Hep G2 , Humanos , Mecanotransducción Celular , Metacrilatos/química , Neoplasias/química , Microambiente Tumoral
8.
Int J Infect Control ; 16(3): 1-6, 2020 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-34135996

RESUMEN

Infection control and antimicrobial stewardship programs (ICASPs) are essential to reduce the emergence and spread of antimicrobial resistance. The primary objective of this study was to assess the feasibility of extending a commercial off-the-shelf (COTS) software for ICASPs in low- and middle-income countries (LMICs). This project involved three hospitals in Colombia, including Centro Médico Imbanaco, Clínica San Francisco, and DIME Clínica Neurocardiovascular. A COTS platform (ILÚM Health Solutions™ Kenilworth, NJ) was extended to function in a range of technology settings, and translatable to almost any language. ICASP features were added, including clinical practice guidelines, hand hygiene (HH) documentation, and isolation precaution (IP) documentation. The platform was delivered as a smartphone mobile application ("app") for both iOS and Android. The app was successfully implemented at all sites, however, full back-end data integration was not feasible at any site. In contrast to the United States, a suite of surveillance tools and physician-focused decision support without patient data proved to be valuable. Language translation processing occurred quickly and incurred minimal costs. HH and IP compliance tracking were the most used features among ICASP staff; treatment guidelines were most often used by physicians. Use of the app streamlined activities and reduced the time spent on ICASP tasks. Users consistently reported positive impressions including simplicity of design, ease of navigation, and improved efficiency. This ICASP app was feasible in limited-resource settings, highly acceptable to users, and represents an innovative approach to antimicrobial resistance prevention.

9.
Micromachines (Basel) ; 10(9)2019 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-31480301

RESUMEN

Microfluidics has become a very promising technology in recent years, due to its great potential to revolutionize life-science solutions. Generic microfabrication processes have been progressively made available to academic laboratories thanks to cost-effective soft-lithography techniques and enabled important progress in applications like lab-on-chip platforms using rapid- prototyping. However, micron-sized features are required in most designs, especially in biomimetic cell culture platforms, imposing elevated costs of production associated with lithography and limiting the use of such devices. In most cases, however, only a small portion of the structures require high-resolution and cost may be decreased. In this work, we present a replica-molding method separating the fabrication steps of low (macro) and high (micro) resolutions and then merging the two scales in a single chip. The method consists of fabricating the largest possible area in inexpensive macromolds using simple techniques such as plastics micromilling, laser microfabrication, or even by shrinking printed polystyrene sheets. The microfeatures were made on a separated mold or onto existing macromolds using photolithography or 2-photon lithography. By limiting the expensive area to the essential, the time and cost of fabrication can be reduced. Polydimethylsiloxane (PDMS) microfluidic chips were successfully fabricated from the constructed molds and tested to validate our micro-macro method.

10.
Artículo en Inglés | MEDLINE | ID: mdl-31109024

RESUMEN

Chikungunya virus (CHIKV) and Zika virus (ZIKV) have recently emerged as globally important infections. This study aimed to explore the spatiotemporal heterogeneity in the occurrence of CHIKV and ZIKV outbreaks throughout the major international seaport city of Barranquilla, Colombia in 2014 and 2016 and the potential for clustering. Incidence data were fitted using multiple Bayesian Poisson models based on multiple explanatory variables as potential risk factors identified from other studies and options for random effects. A best fit model was used to analyse their case incidence risks and identify any risk factors during their epidemics. Neighbourhoods in the northern region were hotspots for both CHIKV and ZIKV outbreaks. Additional hotspots occurred in the southwestern and some eastern/southeastern areas during their outbreaks containing part of, or immediately adjacent to, the major circular city road with its import/export cargo warehouses and harbour area. Multivariate conditional autoregressive models strongly identified higher socioeconomic strata and living in a neighbourhood near a major road as risk factors for ZIKV case incidences. These findings will help to appropriately focus vector control efforts but also challenge the belief that these infections are driven by social vulnerability and merit further study both in Barranquilla and throughout the world's tropical and subtropical regions.


Asunto(s)
Fiebre Chikungunya/epidemiología , Infección por el Virus Zika/epidemiología , Teorema de Bayes , Colombia/epidemiología , Brotes de Enfermedades , Femenino , Humanos , Incidencia , Masculino , Factores de Riesgo
11.
Micromachines (Basel) ; 9(4)2018 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-30424120

RESUMEN

The development of organ-on-chip and biological scaffolds is currently requiring simpler methods for microstructure biocompatible materials in three dimensions, to fabricate structural and functional elements in biomaterials, or modify the physicochemical properties of desired substrates. Aiming at addressing this need, a low-power CD-DVD-Blu-ray laser pickup head was mounted on a programmable three-axis micro-displacement system in order to modify the surface of polymeric materials in a local fashion. Thanks to a specially-designed method using a strongly absorbing additive coating the materials of interest, it has been possible to establish and precisely control processes useful in microtechnology for biomedical applications. The system was upgraded with Blu-ray laser for additive manufacturing and ablation on a single platform. In this work, we present the application of these fabrication techniques to the development of biomimetic cellular culture platforms thanks to the simple integration of several features typically achieved with traditional, less cost-effective microtechnology methods in one step or through replica-molding. Our straightforward approach indeed enables great control of local laser microablation or polymerization for true on-demand biomimetic micropatterned designs in transparent polymers and hydrogels and is allowing integration of microfluidics, microelectronics, surface microstructuring, and transfer of superficial protein micropatterns on a variety of biocompatible materials.

12.
Cir Cir ; 77(2): 101-5, 2009.
Artículo en Español | MEDLINE | ID: mdl-19534859

RESUMEN

BACKGROUND: Instability of the cervical spine is defined as an increase in flexibility farther than the physiological limits of one vertebra over another in some of its axes, conditioning symptoms for the patient. Traumatic, degenerative, metabolic and neoplastic causes have all been identified. METHODS: A retrospective, longitudinal, observational and descriptive study was carried out on patients surgically intervened specifically for atlantoaxial instability from January 1993 to May 2002, with a minimum 5-year follow-up. RESULTS: Eleven patients were evaluated. Ages ranged from 25 to 75 years (average age 56 years) with a female predominance. Etiology was iatrogenic in six cases, and there were four cases of rheumatoid arthritis and one case due to trauma. In all cases, fixation was accomplished with occipitocervical arthrodesis with posterior arch resection. Predominant preoperative neurologic deficit according to Ranawat was grade II and postoperatively was grade I. CONCLUSIONS: The average age of patients in our series was discreetly lower in regard to what has been reported in the literature. Female predominance was in accordance with previous publications. Eight of 11 patients showed improvement as in other series. A higher impact was observed in patients between 30 and 64 years of age. The occupational activity with the highest frequency was homemaker, and the neurologic deficit according to Ranawat showed improvement in 72% of the patients.


Asunto(s)
Articulación Atlantoaxoidea , Inestabilidad de la Articulación/cirugía , Adulto , Anciano , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Estudios Retrospectivos
13.
Cir. & cir ; Cir. & cir;77(2): 101-105, mar.-abr. 2009. ilus
Artículo en Español | LILACS | ID: lil-566651

RESUMEN

Introducción: La inestabilidad de la columna cervical es el aumento en la movilidad más allá de los límites fisiológicos de una vértebra sobre otra en alguno de sus ejes, que condiciona síntomas en el paciente. Existen causas traumáticas, degenerativas, metabólicas y neoplásicas. Material y métodos: Se realizó estudio retrospectivo, longitudinal, observacional y descriptivo, de intervención deliberada, en pacientes con cirugía por inestabilidad atlantoaxoidea, de enero de 1993 a mayo de 2002, con un seguimiento mínimo de cinco años. Resultados: Se evaluaron 11 pacientes, con edades de 25 a 75 años, media de 56 años. El sexo predominante fue el femenino. La etiología fue iatrogénica en seis casos, cuatro por artritis reumatoide y uno postraumática. En todos se realizó fijación y artrodesis occipitocervical con resección del arco posterior. El déficit neurológico preoperatorio predominante según la escala de Ranawat fue grado II, y en el posoperatorio fue grado I. Conclusiones: La edad media de nuestra serie fue discretamente menor respecto a la indicada en la literatura; el sexo predominante correspondió a lo informado en la literatura. Existió mejoría en ocho de los 11 pacientes, como en otras series. La mayor incidencia se observó entre los 30 y 64 años. La actividad ocupacional con mayor frecuencia fue la del hogar. El déficit neurológico según la escala de Ranawat mejoró en 72 % de los pacientes.


BACKGROUND: Instability of the cervical spine is defined as an increase in flexibility farther than the physiological limits of one vertebra over another in some of its axes, conditioning symptoms for the patient. Traumatic, degenerative, metabolic and neoplastic causes have all been identified. METHODS: A retrospective, longitudinal, observational and descriptive study was carried out on patients surgically intervened specifically for atlantoaxial instability from January 1993 to May 2002, with a minimum 5-year follow-up. RESULTS: Eleven patients were evaluated. Ages ranged from 25 to 75 years (average age 56 years) with a female predominance. Etiology was iatrogenic in six cases, and there were four cases of rheumatoid arthritis and one case due to trauma. In all cases, fixation was accomplished with occipitocervical arthrodesis with posterior arch resection. Predominant preoperative neurologic deficit according to Ranawat was grade II and postoperatively was grade I. CONCLUSIONS: The average age of patients in our series was discreetly lower in regard to what has been reported in the literature. Female predominance was in accordance with previous publications. Eight of 11 patients showed improvement as in other series. A higher impact was observed in patients between 30 and 64 years of age. The occupational activity with the highest frequency was homemaker, and the neurologic deficit according to Ranawat showed improvement in 72% of the patients.


Asunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Articulación Atlantoaxoidea , Inestabilidad de la Articulación/cirugía , Estudios Longitudinales , Estudios Retrospectivos
14.
Cir Cir ; 76(2): 165-8, 2008.
Artículo en Español | MEDLINE | ID: mdl-18492439

RESUMEN

BACKGROUND: Phyllodes tumors occur with a frequency of 0.3- 0.9% and are rare in young women. Their clinical presentation is unilateral and behavior and management are unclear. We present a phyllodes tumor in an 11-year-old female and we reviewed the literature regarding this pathology. CASE REPORT: We present the case of an 11-year-old female with a diagnosis of phyllodes tumor. Her disease began 4 months previously. We made an incision biopsy followed by simple mastectomy. Histological report demonstrated benign phyllodes tumor. The patient is currently disease free after 1 year. CONCLUSIONS: Small phyllodes tumors can be excised with a 1-cm surgical border, whereas larger phyllodes tumors are treated with simple mastectomy. Precise pathological evaluation is necessary to plan a better surgical approach and to determine recurrence possibility.


Asunto(s)
Neoplasias de la Mama , Tumor Filoide , Neoplasias de la Mama/patología , Neoplasias de la Mama/cirugía , Niño , Femenino , Humanos , Mastectomía , Tumor Filoide/patología , Tumor Filoide/cirugía
15.
Cir. & cir ; Cir. & cir;76(2): 165-168, mar.-abr. 2008. ilus
Artículo en Español | LILACS | ID: lil-567670

RESUMEN

BACKGROUND: Phyllodes tumors occur with a frequency of 0.3- 0.9% and are rare in young women. Their clinical presentation is unilateral and behavior and management are unclear. We present a phyllodes tumor in an 11-year-old female and we reviewed the literature regarding this pathology. CASE REPORT: We present the case of an 11-year-old female with a diagnosis of phyllodes tumor. Her disease began 4 months previously. We made an incision biopsy followed by simple mastectomy. Histological report demonstrated benign phyllodes tumor. The patient is currently disease free after 1 year. CONCLUSIONS: Small phyllodes tumors can be excised with a 1-cm surgical border, whereas larger phyllodes tumors are treated with simple mastectomy. Precise pathological evaluation is necessary to plan a better surgical approach and to determine recurrence possibility.


Asunto(s)
Humanos , Femenino , Niño , Neoplasias de la Mama , Tumor Filoide , Mastectomía , Neoplasias de la Mama/patología , Neoplasias de la Mama/cirugía , Tumor Filoide/patología , Tumor Filoide/cirugía
16.
Acta Ortop Mex ; 21(4): 204-11, 2007.
Artículo en Español | MEDLINE | ID: mdl-17970561

RESUMEN

The concept of spinal instability is still controversial. Anatomical, biomechanical, clinical and radiographic variants are involved and make the definition complicated. There are solid diagnostic bases in cases of fractures and degenerative disorders; however, pure spinal instability is still under study. The latter may be defined as increased mobility that goes beyond the physiological limits of one vertebra over another in at least one of the three spinal planes of motion. In the case of the craniocervical region, its understanding becomes even more challenging, since its anatomy and physiology are more complex and it is more mobile. Surgical treatment is possible with either an anterior or a posterior approach. Best results are obtained with occipitocervical or atlantoaxial stabilization through a posterior approach, since the anterior one has its limitations. For example, a transoral approach with a bone graft provides compression strength but does not enable immediate appropriate fixation and involves the risk of infection. The choice of the surgical approach must consider the patient's medical status, the specific spine levels involved, the extent of neurological compromise, the X-ray abnormalities and the individual pathology. The goals of surgery are achieved through an appropriate anatomical alignment, assuring the protection of the neural elements and achieving proper spine stabilization with as much preservation of the mobile vertebral segments as possible.


Asunto(s)
Artrodesis/métodos , Articulación Atlantoaxoidea/cirugía , Articulación Atlantooccipital/cirugía , Inestabilidad de la Articulación/cirugía , Articulación Atlantoaxoidea/lesiones , Articulación Atlantoaxoidea/fisiopatología , Articulación Atlantooccipital/lesiones , Articulación Atlantooccipital/fisiopatología , Trasplante Óseo , Humanos , Luxaciones Articulares/complicaciones , Luxaciones Articulares/cirugía , Apófisis Odontoides/lesiones , Rango del Movimiento Articular , Fracturas Craneales/complicaciones , Fracturas Craneales/cirugía , Traumatismos de la Médula Espinal/etiología , Traumatismos de la Médula Espinal/prevención & control , Enfermedades de la Columna Vertebral/complicaciones , Enfermedades de la Columna Vertebral/cirugía , Fracturas de la Columna Vertebral/complicaciones , Fracturas de la Columna Vertebral/cirugía , Fusión Vertebral/métodos
17.
Suma psicol ; 14(1): 107-200, mar. 2007. tab
Artículo en Español | LILACS | ID: lil-469009

RESUMEN

El objetivo central del trabajo es identificar la existencia de Grupos Estratégicos y de Grupos Competitivos, en Fondos de Pensiones y Cesantías de Colombia (AFP), para el año 2005, a partir de un enfoque cognitivo. Se realiza una comparación de los grupos identificados bajo las percepciones de tres poblaciones (directivos de AFP, empresas cliente y afiliados), obtenidas por tres métodos: categorización, citación directa y evaluación. Luego de una revisión detallada sobre los principales enfoques utilizados para definir Grupos Estratégicos y Competitivos, resaltamos el sentido que tiene el realizar análisis de competencia en función de estos dos conceptos; y a nivel empírico, utilizamos datos “subjetivos” de oferta y demanda, para identificar su presencia en este sector industrial. Se revisa la proximidad (similitud) o distanciamiento (diferencia) entre estos dos conceptos, a la luz de la revisión teórica y de la evidencia empírica, a fin de contrastar nuestras hipótesis de investigación; y al mismo tiempo, identificar si existe soporte conceptual y empírico del aporte que brindan en los análisis y teorías de competencia. Su aplicación al caso de las AFP en Colombia se justifica por varias razones:1. La inexistencia en el país, y en este sector en particular, de análisis de competencia realizados bajo un enfoque conjunto sobre grupos estratégicos y competitivos.2. La estructura misma de este sector colombiano, su más reciente evolución y peso creciente en la economía del país.3. Porque su afianzamiento conceptual se relaciona con el desarrollo de nuevos trabajos de validación empírica; máxime si en la literatura no se encontraron intentos de análisis de competencia donde se utilicen conjuntamente ambos conceptos. Siguiendo los enfoques cognitivo e interrelaciones, con origen en las “teorías psicológicas del constructo personal”, interesa identificar la posible existencia de grupos estratégicos y competitivos al interior de las AFP colombianas.


Asunto(s)
Análisis por Conglomerados , Economía , Pensiones , Comportamiento del Consumidor , Toma de Decisiones
18.
La Paz; 2003. 236 p. ilus.
Tesis en Español | LIBOCS, LIBOSP | ID: biblio-1312448

RESUMEN

El objetivo es desarrollar una aplicación de software para calculadoras que no disponen de un lenguaje de programación standar, ello bajo los principios de optimización de espacio de almacenamiento, velocidad, reusabilidad, integridad y portabilidad.Con el fin de poder emular la operación de microprocesadores en un entorno de entrenamiento.La concepción del proyecto se fundamenta en un fuerte énfasis en la generalidad y particularidad académica, que permita definir una línea de conocimiento para el diseño y construcción de emuladores de microprocesadores, multiprocesadores y/o transputer.

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