5,607 research outputs found
Highly-complex optical signal generation using electro-optical systems with non-linear, non-invertible transmission functions
We present a scheme whereby a static non-linear, non-invertible transmission
function performed by the electro-optic Mach-Zehnder modulator produces highly
complex optical chaos. The scheme allows the deterministic transformation of
low-dimensional band-limited chaotic signals into much higher-dimensional
structures with broadband spectra and without using any delay elements or
feedback. Standard benchmark tests show that all the considered complexity
indices are highly increased due to this transformation in a controlled
fashion. This mechanism allows the design of simple optoelectronic delayed
oscillators with extremely complex chaotic output.Comment: 4 pages, 5 figures. To appear in Applied Physics Letters (August
2012
Cibercultur@ as a strategy for complex communication from the edge
Las sociedades que han sido históricamente desplazadas de los “beneficios” de la globalización, tienen la necesidad estratégica de conocer las formas concretas en que sus poblaciones se relacionan con las tecnologías, con la información, con la comunicación y con el conocimiento. Mediante este proceso de apropiación es posible diseñar y desplegar una estrategia crítica y propositiva que les permita no sólo disminuir, sino reorientar los efectos perniciosos (desplazamiento, incomunicación, desconocimiento, desinformación) debidos a la fuerza y dirección del vector tecnológico que se imponen en la densidad de la vida cotidiana de dichas sociedades.Societies that have been historically off the benefits of globalisation, do need to know the ways and means whereby their peoples display technologies, knowledge, information and communication. For it is only through this knowledge that they will produce their own strategies and lay the ground for devising a critical move to downplay and bypass the undesired effects (miscommunication, lack of knowledge and information) that the technological vector carries, and gear the direction and strength of this such a vector in the daily life of those peoples
El debate de la seguridad en América Latina
Se da cuenta del incremento de la violencia y el delito vividos en América Latina y se señalan las estrategias seguidas por algunos actores latinoamericanos frente al asunto. La simple generación de oportunidades no es suficiente para disminuir el delito sino que es necesario fortalecer la dimensión asociativa y comunitaria.ITESO, A.C
Performance and ownership in the governance of urban water
In this paper the differences in terms of performance between public and the private governance in urban water management are investigated. A statistical ranking is implemented to determine programmatic efficiency differences in DEA, using an incomplete panel data that gathers information on 20 water utilities in Andalusia, in Southern Spain. In the model, labour and operational costs are considered as inputs. The volume of revenue water, the number of connections and the network length are used as outputs. The analysis indicates that private management is more efficient. The efficiency indicators adjusted by a variable related to quality are estimated and demonstrate that privatization of the service does not mean any loss in terms of quality. However, there are no significant differences between both types of management including as a desirable input hydraulic yield as a proxy of the degree of network renovation. A lower hydraulic efficiency in private management would suggest that the need to make significant investments could be an important factor when making the decision to privatize the management of the urban water service: Water supply; Management; Local government;
Pressure-induced structural, electronic, and magnetic effects in BiFeO3
We present a first-principles study of multiferroic BiFeO3 at high pressures.
Our work reveals the main structural (change in Bi's coordination and loss of
ferroelectricity), electronic (spin crossover and metallization), and magnetic
(loss of order) effects favored by compression and how they are connected. Our
results are consistent with the striking manifold transition observed
experimentally by Gavriliuk et al. [Phys. Rev. B 77, 155112 (2008)] and provide
an explanation for it.Comment: 4 pages with 4 figures embedded. More information at
http://www.icmab.es/dmmis/leem/jorg
What is the best alternative to the use of cycloplegic in the objective refraction
Comunicação Ora
Influence of fogging lenses and cycloplegia on peripheral refraction
Purpose: To compare objective peripheral refraction measured
with an open-field autorefractor without cycloplegia with the
values obtained with fogging lenses or with cycloplegia to inhibit
accommodation.
Methods: For one hundred and sixty young adults aged 18 to 28
(mean 21.5 ± 2.3 years) their refraction was measured with the Grand
Seiko (GS) autorefractor at the center and at four peripheral locations
in the nasal and temporal directions under three different conditions:
1) without cycloplegia (GS); 2) without cycloplegia, but using a
+2.00D fogging lens (GS_2D) and 3) with cycloplegia (GS_cycl).
Results: Mean spherical equivalent refraction (M) was significantly
more negative with the GS method in the hyperopic group
for central and peripheral refraction, and only at the center and at
10º nasal eccentricity for the emmetropic group (P<0.05, Kruskal-
Wallis). Paired comparison showed that differences of M values
across techniques were larger for the GS-vs.-GS_2D comparison in
myopes and emmetropes, and for the GS-vs.-GS_cycl one in hyperopes
(P<0.001, Wilcoxon Signed Ranks Test). The gap between M
values for all paired comparisons remained almost constant across
all eccentric positions under analysis.
Conclusions: Fogging lenses used with open-field autorefraction
up to 20º in the nasal and temporal fields seem to provide similar
accommodative relaxation to that provided by a cycloplegic. This is
particularly important when refracting emmetropes and hyperopes.
Moreover, this behavior seems to be independent of the eccentricity
at which measurements are taken.Objetivo: Comparar las medidas objetivas de refracción periférica
realizadas sin cicloplégico con los valores obtenidos con “lentes de
miopización” o con cicloplegia, ambas técnicas utilizadas para inhibir
la acomodación.
Métodos: Se midió la refracción a 160 adultos jóvenes, con edades
comprendidas entre 18 y 28 años (media=21,5± 2,3 años), con un
autorrefractómetro Grand Seiko (GS), tanto en el centro del campo
visual como en 4 regiones de la periferia situadas nasal y temporalmente,
y todo ello en 3 condiciones diferentes: 1) sin cicloplegia
(GS); 2) sin cicloplegia , pero utilizando una lente translúcida de
+2.00 D (GS_2D) y 3) con cicloplegia (GS_cycl).
Resultados: La media del equivalente esférico de la refracción
(M) resultó ser significativamente más negativa en la condición GS
en el grupo de los hipermétropes en lo que respecta a refracción
central y periférica, mientras que en el grupo de los emétropes sólo
ocurrió esto en el centro y a una excentricidad de 10º nasal (P<0,05,
Kruskal-Wallis). La comparación por pares de muestras relacionadas
reveló que la mayor diferencia de M entre distintas condiciones se
obtuvo al comparar GS y GS_2D en el grupo de los miopes y en
el de los emétropes, y al comparar GS y GS_cycl en el de los hipermétropes
(P<0,001, contraste de Wilcoxon de rangos con signo).
La discrepancia entre valores de M para las distintas comparaciones
por pares se mantiene prácticamente constante para todas las excentricidades
analizadas.
Conclusiones: Las lentes de miopización, utilizadas con un autorrefractómetro
con ventana de observación para medir excentricidades
de hasta 20º en las direcciones nasal y temporal parece que
logran una relajación acomodativa similar a la que proporciona el
agente cicloplégico. Esto resulta especialmente relevante cuando se
evalúa la refracción en emétropes e hipermétropes. Además, este
comportamiento parece ser independiente de la excentricidad en la
que se realiza la medida.(undefined
Functional and structural modifications associated with hypertension, obesity and diabetes in the resistance vasculature
"December 2014."Dissertation Supervisors: Dr. Luis A. Martinez-Lemus and Luis Polo-Parada.Includes vita.Cardiovascular diseases are considered the leading cause of death nowadays. Hypertension, obesity and type-2 diabetes are deemed major risk factors for the development of cardiovascular diseases. In essential hypertension, one of the most important structural changes is the inward remodeling of the resistance arteries. I found that the mechanical properties of inwardly remodeled cremasteric-arterioles from rats are affected. Furthermore, it is the F-actin components of the cytoskeleton the ones that are strongly modified. In old spontaneously hypertensive rats, my results showed that, resistance arteries undergo hypertrophic inward remodeling; and, adrenergicvasoconstriction and vasodilation pathways are impaired. In diet-induced-obesity, micemesenteric arterioles were observed to undergo remodeling of the extracellular matrix components. Obesity and type-2 diabetes have been associated with insulin resistance, endothelial dysfunction and arterial stiffening. Jejunal-submucosal arterioles from diabetic obese patients had a reduced vasorelaxation to insulin in comparison to obese non-diabetics, while acetylcholine-vasodilation was similar in both groups. Reduced amounts of the subunit-alpha of the insulin receptor and MMP-9 were found in diabetics as well. This suggests that, in type-2 diabetes, the presence of a blunted insulinvasodilation response is a form of endothelial dysfunction that is not correlated with the body-to-mass index, but whose mechanism may be related with the activity of MMPs.Includes bibliographical references (pages 124-146)
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