La carrera docente en la Provincia de Buenos Aires: análisis y propuestas de mejora

Las carreras docentes latinoamericanas han sido agrupadas en dos conjuntos, de acuerdo con factores como los mecanismos de ingreso, de ascenso y de evaluación: carreras “de primera generación” de ascenso vertical y carreras “de segunda generación” horizontales (Cuenca, 2015). El plan de carrera vigente en la Provincia de Buenos Aires –en sintonía con las demás jurisdicciones de la República Argentina– corresponde al primer grupo. Esta tesis reseña la historia de los cuatro documentos que determinan las características de la carrera docente bonaerense. A continuación, la describe en lo que concierne a ingreso, contrato laboral, estabilidad, escalafón y ascensos, salarios, licencias, capacitación, evaluación del desempeño y funciones de los directores. Teniendo en cuenta los conceptos de plan de carrera, calidad educativa, regulación e incentivos se analiza el plan de carrera descrito y sus controversias. Finalmente, se plantean propuestas para su mejor

Stationary patterns in star networks of bistable units: theory and application to chemical reactions

We present theoretical and experimental studies on pattern formation with bistable dynamical units coupled in a star network configuration. By applying a localized perturbation to the central or the peripheral elements, we demonstrate the subsequent spreading, pinning, or retraction of the activations; such analysis enables the characterization of the formation of stationary patterns of localized activity. The results are interpreted with a theoretical analysis of a simplified bistable reaction-diffusion model. Weak coupling results in trivial pinned states where the activation cannot propagate. At strong coupling, a uniform state is expected with active or inactive elements at small or large degree networks, respectively. A nontrivial stationary spatial pattern, corresponding to an activation pinning, is predicted to occur at an intermediate number of peripheral elements and at intermediate coupling strengths, where the central activation of the network is pinned, but the peripheral activation propagates toward the center. The results are confirmed in experiments with star networks of bistable electrochemical reactions. The experiments confirm the existence of the stationary spatial patterns and the dependence of coupling strength on the number of peripheral elements for transitions between pinned and retreating or spreading fronts in forced network configurations (where the central or periphery elements are forced to maintain their states)

Semantic Matching of Components at run-time in Distributed Environments

Software factories are a key element in Component-Based Software Engineering due to the common space provided for software reuse through repositories of components. These repositories can be developed by third parties in order to be inspected and used by different organizations, and they can also be distributed in different locations. Therefore, there is a need for a trading service that manages all available components. In this paper, we describe a matching process based on syntactic and semantic information of software components. This matching operation is part of a trading service which is in charge of generating configurations of components from architectural definitions. With this aim, the proposed matching allows us to evaluate and score the possible configurations, thus guiding a search process to build the architectural solution which best fulfills an input definition

Evaluating the potential impact of bird predation on the SW Atlantic fiddler crab Leptuca uruguayensis

The southernmost permanent population of the fiddler crab Leptuca uruguayensis occurs along the Samborombón Bay (36°22′S, 56°45′W, Argentina), an important feeding site for many bird species, including ruddy turnstones (Arenaria interpres), whimbrels (Numenius phaeopus), grey plovers (Pluvialis squatarola), american golden plovers (Pluvialis dominica) and gull-billed terns (Gelochelidon nilotica). Although all these birds are known to prey on many fiddler crab species worldwide, there is no estimation of their joint predation impacts, probably due to the difficulty in conducting experiments on an appropriate spatial scale. In these situations, computer simulation methods are useful tools. By using Monte Carlo methods and field data, we modeled the decrease of a fiddler crab population due to bird predation. The model found that under current bird occurrences and crab densities, birds do not consume more than 0.03% of the studied fiddler crab populations. Birds only consume more than 10% of the population if crab density is below 0.02 crabs m2, or if bird occurrences are at least 3 orders of magnitude higher than currently observed. Both situations are unlikely, as mean crab density is 140 crabs m2, and bird density is never so high. Furthermore, by monitoring three different fiddler crab patches, we found that bird predation cannot account for temporal density changes, suggesting that other population processes are more important than bird predation. In conclusion, even though fiddler crabs may exhibit strong predator-Avoidance behavior, direct lethal effects of bird predation are currently small.Fil: Ribeiro, Pablo Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Navarro, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Jaureguy, Luciano M.. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; ArgentinaFil: Daleo, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Iribarne, Oscar Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

PTL: A Model Transformation Language based on Logic Programming

In this paper we present a model transformation language based on logic programming. The language, called PTL (Prolog based Transformation Language), can be considered as a hybrid language in which ATL (Atlas Transformation Language)-style rules are combined with logic rules for defining transformations. ATL-style rules are used to define mappings from source models to target models while logic rules are used as helpers. The implementation of PTL is based on the encoding of the ATL-style rules by Prolog rules. Thus, PTL makes use of Prolog as a transformation engine. We have provided a declarative semantics to PTL and proved the semantics equivalent to the encoded program. We have studied an encoding of OCL (Object Constraint Language) with Prolog goals in order to map ATL to PTL. Thus a subset of PTL can be considered equivalent to a subset of ATL. The proposed language can be also used for model validation, that is, for checking constraints on models and transformations. We have equipped our language with debugging and tracing capabilities which help developers to detect programming errors in PTL rules. Additionally, we have developed an Eclipse plugin for editing PTL programs, as well as for debugging, tracing and validation. Finally, we have evaluated the language with several transformation examples as well as tested the performance with large models

Nutrient and herbivore alterations cause uncoupled changes in producer diversity, biomass and ecosystem function, but not in overall multifunctionality

Altered nutrient cycles and consumer populations are among the top anthropogenic influences on ecosystems. However, studies on the simultaneous impacts of human-driven environmental alterations on ecosystem functions, and the overall change in system multifunctionality are scarce. We used estuarine tidal flats to study the effects of changes in herbivore density and nutrient availability on benthic microalgae (diversity, abundance and biomass) and ecosystem functions (N2-fixation, denitrification, extracellular polymeric substances -EPS- as a proxy for sediment cohesiveness, sediment water content as a proxy of water retention capacity and sediment organic matter). We found consistent strong impacts of modified herbivory and weak effects of increased nutrient availability on the abundance, biomass and diversity of benthic microalgae. However, the effects on specific ecosystem functions were disparate. Some functions were independently affected by nutrient addition (N2-fixation), modified herbivory (sediment organic matter and water content), or their interaction (denitrification), while others were not affected (EPS). Overall system multifunction remained invariant despite changes in specific functions. This study reveals that anthropogenic pressures can induce decoupled effects between community structure and specific ecosystem functions. Our results highlight the need to address several ecosystem functions simultaneously for better ecosystem characterization and management.Instituto de Limnología "Dr. Raul A. Ringuelet

Simulating Rainfall, Water Evaporation and Groundwater Flow in Three-Dimensional Satellite Images with Cellular Automata

Remote sensing has been used in numerous environmental simulations with the aim of solving and improving many different kinds of problems, e.g., meteorology applications, soil quality studies, water resource exploration, and environmental protection. Besides, cellular automata have been widely used in the field of remote sensing for simulating natural phenomena over two-dimensional satellite images. However, simulations on Digital Elevation Models (DEM), or three-dimensional (3D) satellite images, are scarce. This paper presents a study of modeling and simulation of the weather phenomena of rainfall, water evaporation and groundwater flow in 3D satellite images through a new algorithm, developed by the authors, named RACA (Rainfall with Cellular Automata). The purpose of RACA is to obtain, from the simulation, numerical and 3D results related to the total cumulative flow and maximum level of water that allow us to make decisions on important issues such as analyzing how climate change will affect the water level in a particular area, estimating the future water supply of a population, establishing future construction projects and urban planning away from locations with high probability of flooding, or preventing the destruction of property and human life from future natural disasters in urban areas with probability of flooding

Controlling Retinal Pigment Epithelium Injury after Experimental Detachment of the Retina

PURPOSE. Damage induced by detachment of the neural retina and the retinal pigment epithelium (RPE) can be reduced by dark adaptation. The authors evaluated the influence of the duration of dark adaptation, time of day, and modification of the melatonin-dopamine pathway on acute RPE lesions induced by mechanical detachment. METHODS. BALB/c mice were studied at different times of day and different periods of dark adaptation. Some mice were treated with melatonin or sulpiride, a D2 dopamine receptor antagonist. Enucleated eyes and different saline solutions were used in experiments ex vivo. Retinal detachments in vivo were made by subretinal injections of hyaluronic acid. RPE cell damage was quantitatively evaluated with a dye exclusion procedure, and their viability was tested by preservation of tight junctions in culture. Lectin histochemistry was used to examine the interphotoreceptor matrix (IPM). RESULTS. Significant propidium iodide (PI) incorporation in RPE cells was detected after ex vivo separation during daytime, but it was very low when detachment took place at night after 24 to 48 hours of dark adaptation. PI exclusion was achieved during daytime after a single hour of dark adaptation when mice were pretreated with melatonin or sulpiride. Reduction of RPE cell damage was accompanied by decreased lectin binding to cone sheaths. CONCLUSIONS. A combination of time of day and length of dark adaptation decreased damage induced by detachment of the retina ex vivo and in vivo. Melatonin or sulpiride could replace these environmental factors. Therefore, melatonin and dopamine pathways might be involved in the control of IPM properties and retina/RPE interactions. (Invest Ophthalmol Vis Sci. 2007;48:1348 -1354) DOI:10.1167/iovs.06-0964 A rtificial separation of the neural retina and the retinal pigment epithelium (RPE) is sometimes performed for specific purposes such as excision of a subretinal membrane, reapplication of a detached and folded retina, or performance of macular translocation surgery. 1,2 Recovery of visual function depends on the reestablishment of functional associations among these layers. Because of the close anatomic interdigitation of photoreceptor outer segments and RPE microvilli, epithelial cells may remain attached to the retina when RPE is mechanically separated. This phenomenon has been used to evaluate neural retina/RPE adhesion strength. 3,4 Attachment also depends on cone sheaths, a specialized region of the interphotoreceptor matrix (IPM) that encases outer and inner segments of cone (but not rod) photoreceptors. 10 Melatonin is rhythmically synthesized in the retina and acts as a neuromodulator imparting photoperiodic information to the retina. Although we have been able to obtain RPE laminae of high morphologic quality after an hour of dark adaptation, we found that epithelial structure rapidly deteriorated after a few hours in culture. Therefore, we used propidium iodide (PI) to detect submicroscopic damage to RPE cells that occurred before the appearance of overt necrotic or apoptotic signs. This dyeexclusion procedure has been found useful in several tissues, including RPE cells. MATERIALS AND METHODS Male BALB/c albino mice were handled in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Experimental Conditions Mice were bred under a light/darkness cycle of 12 hours each (7:00 am to 7:00 pm) with maximum illumination levels of 60 lux at the cage floor. At the beginning of experiments, mice were kept in complete darkness between 1 hour and 7 days. Animals were housed in a double enclosure with food and water ad libitum. Feeding and cage cleaning were carried out under a dim red light. One group of animals was submitted to a shifted light cycle (12-hour light/12-hour dark). Surgical procedures were carried out under chloral hydrate anesthesia (400 mg/kg, intraperitoneal) and bulbar topical application with 0.25% proparacaine (diluted Anestalcon; Laboratorios Alcon, Buenos Aires, Argentina). Melatonin (0.05 mg/kg; Sigma-Aldrich Chemical Co., St. Louis, MO) or the D2 dopamine receptor (D2R) antagonist sulpiride (50 mg/kg; Armstrong-Syncro, Buenos Aires, Argentina) was administered subcutaneously. Control animals received similar volumes of saline solution. Injections and experimental procedures were performed by different researchers. Ex Vivo Separation of Neural Retina and RPE Pharmacologic treatments, enucleation, and separation were performed under dim red light and aseptic conditions. Room temperature was set at 28°C because temperature can modify adhesion between retina and RPE. After enucleation, the cornea, lens, and vitreous were dissected through perilimbal incision, and the optic nerve stump was removed From th