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3.
Phys Rev E ; 96(5-1): 052108, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29347694

RESUMO

Hyperbolic lattices interpolate between finite-dimensional lattices and Bethe lattices, and they are interesting in their own right, with ordinary percolation exhibiting not one but two phase transitions. We study four constraint percolation models-k-core percolation (for k=1,2,3) and force-balance percolation-on several tessellations of the hyperbolic plane. By comparing these four different models, our numerical data suggest that all of the k-core models, even for k=3, exhibit behavior similar to ordinary percolation, while the force-balance percolation transition is discontinuous. We also provide proof, for some hyperbolic lattices, of the existence of a critical probability that is less than unity for the force-balance model, so that we can place our interpretation of the numerical data for this model on a more rigorous footing. Finally, we discuss improved numerical methods for determining the two critical probabilities on the hyperbolic lattice for the k-core percolation models.

4.
Gerontol Geriatr Educ ; 36(1): 3-13, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-24717013

RESUMO

A recent dramatic increase in the elderly population has not been accompanied by a parallel increase in specialized health care professionals in Latin America. The main purpose of this work was to determine the stage of geriatrics teaching for undergraduate and graduate medical levels in Latin America. Using a questionnaire given in person and online, the authors surveyed geriatricians from 16 countries: eight from South America and eight from Central America. Among 308 medical schools, 35% taught undergraduate geriatrics, ranging from none in Uruguay, Venezuela, and Guatemala to 82% in Mexico. The authors identified 36 programs in 12 countries with graduate medical education in geriatrics, ranging from 2 to 5 years of training. The authors conclude that although the population is aging rapidly in Latin American countries, there has been a slow development of geriatrics teaching at undergraduate and postgraduate levels in the region.


Assuntos
Educação de Pós-Graduação em Medicina , Educação de Graduação em Medicina , Geriatria/educação , Serviços de Saúde para Idosos , Idoso , Currículo , Educação de Pós-Graduação em Medicina/organização & administração , Educação de Pós-Graduação em Medicina/estatística & dados numéricos , Educação de Graduação em Medicina/organização & administração , Educação de Graduação em Medicina/estatística & dados numéricos , Pesquisas sobre Serviços de Saúde , Serviços de Saúde para Idosos/organização & administração , Serviços de Saúde para Idosos/estatística & dados numéricos , Transição Epidemiológica , Humanos , América Latina , Determinação de Necessidades de Cuidados de Saúde
5.
Soft Matter ; 10(12): 1885-90, 2014 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-24652538

RESUMO

Recent observations demonstrate that confluent tissues exhibit features of glassy dynamics, such as caging behavior and dynamical heterogeneities, although it has remained unclear how single-cell properties control this behavior. Here we develop numerical and theoretical models to calculate energy barriers to cell rearrangements, which help govern cell migration in cell monolayers. In contrast to work on sheared foams, we find that energy barrier heights are exponentially distributed and depend systematically on the cell's number of neighbors. Based on these results, we predict glassy two-time correlation functions for cell motion, with a timescale that increases rapidly as cell activity decreases. These correlation functions are used to construct simple random walks that reproduce the caging behavior observed for cell trajectories in experiments. This work provides a theoretical framework for predicting collective motion of cells in wound-healing, embryogenesis and cancer tumorogenesis.


Assuntos
Movimento Celular/genética , Metabolismo Energético , Células Epiteliais/metabolismo , Desenvolvimento Embrionário/genética , Humanos , Modelos Biológicos , Modelos Teóricos
6.
Artigo em Inglês | MEDLINE | ID: mdl-24483409

RESUMO

We revisit the concept of minimal rigidity as applied to frictionless, repulsive soft sphere packings in two dimensions with the introduction of the jamming graph. Minimal rigidity is a purely combinatorial property encoded via Laman's theorem in two dimensions. It constrains the global, average coordination number of the graph, for example. However, minimal rigidity does not address the geometry of local mechanical stability. The jamming graph contains both properties of global mechanical stability at the onset of jamming and local mechanical stability. We demonstrate how jamming graphs can be constructed using local moves via the Henneberg construction such that these graphs fall under the jurisdiction of correlated percolation. We then probe how jamming graphs destabilize, or become unjammed, by deleting a bond and computing the resulting rigid cluster distribution. We also study how the system restabilizes with the addition of new contacts and how a jamming graph with extra (redundant) contacts destabilizes. The latter endeavor allows us to probe a disk packing in the rigid phase and uncover a potentially new diverging length scale associated with the random deletion of contacts as compared to the study of cut-out (or frozen-in) subsystems.

7.
Rev. colomb. anestesiol ; 36(4): 279-286, dic. 2008. tab
Artigo em Espanhol | LILACS, COLNAL | ID: lil-636003

RESUMO

A medida que la población envejece, más pacientes geriátricos deben someterse a cirugías, bien sea electivas o urgentes. Dado que el envejecimiento es una experiencia única y personal, cada paciente que va ser sometido a cirugía debe abordarse de manera individual. La valoración de la reserva funcional ha llegado a ser la piedra angular en el plan anestésico y es marcador pronóstico integral. Se dan pautas para su valoración, así como de la capacidad funcional, con el fin de minimizar los riesgos de la anestesia y la cirugía. En la presente revisión se discuten los cambios de los órganos con la edad, el papel de las enfermedades intercurrentes como factores determinantes del riesgo, otros factores que incrementan el riesgo de complicaciones y los problemas perioperatorios que se pueden presentar, entre otros, los relacionados con el estado cognitivo.


As the population ages, more geriatric patients should undergo Esther elective or urgent surgery. Given that ageing is a unique and individual experience, each patient that goes to surgery, must be addressed on an individual basis. The assessment of the functional reserve has become the cornerstone in the anesthetic plan and is the fore-casting integral marker. Guidelines for its assessment are given, as well as its functional capacity, in order to minimize the risks of anesthesia and surgery. In this review, changes in organs with age, the role of intercurrent diseases, and other factors that increase the risk of complications, perioperative problems that may arise, including those related to cognitive stes are discussed.


Assuntos
Humanos
8.
Acta méd. colomb ; 17(4): 216-20, jul.-ago. 1992. tab
Artigo em Espanhol | LILACS | ID: lil-183242

RESUMO

Con el fin de analizar las principales características de la población mayor de 65 años vista en el Hospital San Juan de Dios de Bogotá, se realizó un estudio retrospectivo sobre 632 historias clínicas. El promedio de edad fue de 73.1 años. Apreciamos una relación directa entre la edad y la estancia hospitalaria con un promedio global de 15.9 días-paciente. El diagnóstico de egreso más frecuente fue la enfermedad cerebrovascular (8.2 por ciento), y reuniendo en un solo grupo las enfermedades del sistema cardiovascular, representarían 14 por ciento de los casos. Los traumatismos aparecen como causa importante de morbilidad. La mortalidad global fue de 8.9 por ciento, siendo la enfermedad cerebrovascular y la falla cardíaca con 12 casos cada una, las dos primeras causas de muerte; como dato alarmante la septicemia ocupó el tercer lugar. Se concluye que es necesario fomentar el estudio y la investigación en este grupo poblacional, cada vez más creciente.


Assuntos
Humanos , Idoso , /estatística & dados numéricos , Doenças Cardiovasculares/epidemiologia , Transtornos Cerebrovasculares/epidemiologia , Geriatria/estatística & dados numéricos , Morbidade
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