Composição isotópica Sr-Nd de granitos subalcalinos ferro-potássicos: o maciço granítico de Peneda-Gerês (NW Península Ibérica)

The Peneda-Gerês granitic massif is a good example of a post-tectonic Variscan massif. The granites are dominantly of subalkaline Fe-K affinity. The integration of geological, mineralogical, chemical and isotopic data suggests that this massif is the result of the emplacement of at least three intrusive magmas (Gerês-Covas, Calvos and Paufito-Illa-Carris) that evolved independently. A comparative study with other late-Variscan subalkaline granites of Portugal and other regions reveals that the isotope composition is globally weakly evolved (Sri = 0.7030-0.7069; eNdi = -1.0 to -2.5). The origin of these magmas by partial fusion of lower crustal material or, instead, a mixture between a depleted mantle component and a crustal component is discussed. For the Calvos granite a lower crustal protolith seems most probable while, for the other granites, the interaction between mafic mantle-derived magmas and the continental crust is the scenario that best explains their characteristics. During the waning stages of the Variscan orogeny, mantle input was most probably considerable

Inverse Ising inference using all the data

We show that a method based on logistic regression, using all the data, solves the inverse Ising problem far better than mean-field calculations relying only on sample pairwise correlation functions, while still computationally feasible for hundreds of nodes. The largest improvement in reconstruction occurs for strong interactions. Using two examples, a diluted Sherrington-Kirkpatrick model and a two-dimensional lattice, we also show that interaction topologies can be recovered from few samples with good accuracy and that the use of $l_1$-regularization is beneficial in this process, pushing inference abilities further into low-temperature regimes.Comment: 5 pages, 2 figures. Accepted versio

Are visual cortex maps optimized for coverage?

The elegant regularity of maps of variables such as ocular dominance, orientation, and spatial frequency in primary visual cortex has prompted many people to suggest that their structure could be explained by an optimization principle. Up to now, the standard way to test this hypothesis has been to generate artificial maps by optimizing a hypothesized objective function and then to compare these artificial maps with real maps using a variety of quantitative criteria. If the artificial maps are similar to the real maps, this provides some evidence that the real cortex may be optimizing a similar function to the one hypothesized. Recently, a more direct method has been proposed for testing whether real maps represent local optima of an objective function (Swindale, Shoham, Grinvald, Bonhoeffer, & Hilbener, 2000). In this approach, the value of the hypothesized function is calculated for a real map, and then the real map is perturbed in certain ways and the function recalculated. If each of these perturbations leads to a worsening of the function, it is tempting to conclude that the real map is quite likely to represent a local optimum of that function. In this article, we argue that such perturbation results provide only weak evidence in favor of the optimization hypothesis

EXFI: a low cost Fault Injection System for embedded Microprocessor-based Boards

Evaluating the faulty behavior of low-cost embedded microprocessor-based boards is an increasingly important issue, due to their adoption in many safety critical systems. The architecture of a complete Fault Injection environment is proposed, integrating a module for generating a collapsed list of faults, and another for performing their injection and gathering the results. To address this issue, the paper describes a software-implemented Fault Injection approach based on the Trace Exception Mode available in most microprocessors. The authors describe EXFI, a prototypical system implementing the approach, and provide data about some sample benchmark applications. The main advantages of EXFI are the low cost, the good portability, and the high efficienc

Estrutura e geoquí­mica das fases magmática e tardimagmática em zircões do maciço graní­tico de Peneda-Gerês (NW Pení­nsula Ibérica)

Efectuou-se um estudo da estrutura interna e composição química dos zircões de granitos do maciço de Peneda-Gerês (granitos de Gerês, Paufito, Illa e Carris) com recurso a microscópio electrónico de varrimento (MEV) e microssonda electrónica. Este estudo permitiu caracterizar as fases magmática e tardimagmática e, ainda, constatar a existência de domínios de alteração nas zonas dos cristais mais ricas em elementos vestigiais (U, Th). Esta alteração é claramente mais expressiva nos zircões mais tardios (subtipos S5, G1) do granito de Carris e traduz-se em estruturas com forma botrioidal e de cor escura em imagem de electrões retrodifundidos (MEV). A grande expressividade destes domínios de alteração nos zircões do granito de Carris, em constraste com a sua limitada expressividade em zircões dos restantes granitos do maciço de Peneda-Gerês, permite supor que este fenómeno de alteração esteja relacionado com a maior abundância de fluidos hidrotermais que afectaram domínios mais susceptíveis dos cristais de zircão. Refira-se que, espacialmente associados ao granito de Carris, ocorrem filões e filonetes quartzosos e quartzo-feldspáticos com mineralizações em volframite, molibdenite, pirite, etc, correspondendo às zonas mais mineralizadas do maciço de Peneda-Gerês.A study of the internal structure and chemical composition of zircon from the main granitic units of the Peneda-Gerês granitic massif (Gerês, Paufito, Illa and Carris granites) was undertaken. This study permitted to characterize the zircons’ magmatic and late magmatic phases and, additionally, revealed the existence of alteration domains in the zones of the zircons which are richer in trace elements (U, Th). This alteration is notoriously more expressible in the late crystallizing zircons (subtypes S5, G1) of theCarris granite and appears as botrioidal structures of dark colour in back scattered electron imagery (SEM). The important expression of this alteration in the Carris granite, in contrast to the limited expression in zircons of the other granites, permits to envisage that this alteration is associated with a greater abundance of hydrothermal fluids that affected the more susceptible domains of the zircon crystals. It should be referred that spatially associated with the Carris granite occur quartz and quartz-feldspar veins with mineralizations of wolframite, molybdenite, pyrite, etc, corresponding to the most mineralized zone of the Peneda-Gerês massif.Fundação para a Ciência e a Tecnologia (FCT) - Programa de Financiamento Plurianua

Chronology of granitic structures in variscan "folded" granite associated to a shear zone (NW PORTUGAL)

Poster apresentado no 32nd International Geological Congress, Florença, Itália, 20-28 Agosto 2004

Seasonal Thermal Sensation Vote - An indicator for long-term energy performance of dwellings with no HVAC systems

Dwellings with no heating, ventilation and air conditioning (HVAC) systems are commonly found in many countries. The long-term thermal performance of these buildings can be assessed based on hourly data of occupant thermal discomfort integrated over the required timespan (e.g. total degree hours of discomfort per year). This approach can be easily applied when simulation is adopted in the assessment, but field studies using this approach are rare as they would require complex, costly and long measurement/survey campaigns. This paper addresses the challenges on conducting field studies on long-term thermal performance of dwellings with no HVAC system by introducing a novel performance indicator: the Seasonal Thermal Sensation Vote (S-TSV). S-TSV adopts the standard 7-point thermal sensation scale and is based on the perceived overall thermal sensation recalled by the user of the building for specific seasons and times of day. The new performance indicator is not intended to replace existing ones, but to complement them in the understanding of the complex thermal performance processes taking place in buildings with no HVAC. S-TSV was applied in a field study targeting a small sample of dwellings in Brazil. Results demonstrate the capabilities of S-TSV to describe trends in buildings performance in this sample. S-TSV also assisted on the identification of relationships between such performance and some independent variables addressed in this field study (e.g. windows operation, footwear and income), considering a threshold of p-values <0.05 on the chi-square statistic test

Algorithms to infer metabolic flux ratios from fluxomics data

In silico cell simulation approaches based in the use of genome-scale metabolic models (GSMMs) and constraint-based methods such as Flux Balance Analysis are gaining importance, but methods to integrate these approaches with omics data are still greatly needed. In this work, the focus relies on fluxomics data that provide valuable information on the intracellular fluxes, although in many cases in an indirect, incomplete and noisy way. The proposed framework enables the integration of fluxomics data, in the form of 13C labeling distribution for metabolite fragments, with GSMMs enriched with carbon atom transition maps. The algorithms implemented allow to infer labeling distributions for fragments/metabolites not measured and to build expressions for the relevant flux ratios that can be then used to enrich constraint-based methods for flux determination. This approach does not require any assumptions on the metabolic network and reaction reversibility, allowing to compute ratios originating from coupled joint points of the network. Also, when enough data do not exist, the system tries to infer ratio bounds from the measurements

Flexible and user friendly tools for the incorporation of fluxomics data into metabolic models

The measurement of fluxes and the understanding of their control are at the core of Metabolic Engineering (ME). In this context, this work presents two integrated open- source software tools that allow to perform tasks of metabolic flux analysis (MFA). Both are platform independent, written in Java, and interact with the OptFlux framework [1], which also facilitates their communication (Figure 1). OptFlux is a modular open-source software that incorporates tools for strain optimization, i.e., the identification of ME targets. It also provides tools to use stoichiometric metabolic models for phenotype simulation of both wild-type and mutant organisms, using methods such as the well known Flux Balance Analysis (FBA). Graphical user interfaces are made available for every operation and to check the results that are obtained. Moreover, a network visualization system is offered, where simulation results can be added to overlap the network graph. The developed tools exploit OptFluxâ??s capabilities in terms of model interaction, simulation methods and visualization features. The first proposed software, named MetabolIc NEtwork Ratio AnaLysis (MiNeRAl) (Figure 1, bottom), aims at analyzing labeling experiments to infer flux constraints that for stoichiometric models. From a set of measurements of a 13C-labelling experiment, mass isotopomer distribution vectors (MDV) are calculated. If aminoacids are measured, the measured fragments, coupled with a carbon transition map provided by the user, are used to determine their precursors, and the corresponding MDVs are calculated. Based on the set of MDVs, the software uses the carbon transitions to determine the flux ratios that produce a given metabolite through the different pathways. These ratios are probabilistic equations that translate how the 13C-labeling pattern is distributed throughout the metabolic network [2]. Since the calculation of the flux ratios is independent of the flux distribution, this software can be used independently of other flux calculation processes, and the ratios can be further exploited to reduce the degrees of freedom of systems obtained in other MFA approaches [3,4]. The main differentiating characteristics of this tool are, besides being usr-friendly, the fact that it is generic for any type of metabolite fragmentation originating from GC-MS techniques and metabolic network topology. Furthermore, the software is also able to investigate what flux ratio constraints are possible to be inferred for a certain experiment beforehand. On the other hand, the second software application here described, jMFA (Figure 1, top), is focused on using different types of experimental flux data to constrain metabolic models and improve their predictions with a variety of tools. It allows users to define constraints associated with measured fluxes and/ or flux ratios, together with environmental conditions (e.g. media) and reaction/ gene knockouts. The application identifies the set of applicable methods based on the constraints defined from user inputs, allowing to select the desired approach, encompassing algebraic and constraint- based simulation methods (such as Flux Balance Analysis and its variants). Anytime a set of constraints is selected, the software calculates the degrees of freedom of the configured system, and updates the admissible methods depending on whether the system is underdetermined, determined or overdetermined, as shown in Figure 1. A method to perform robustness analysis is also implemented. The integration of jMFA within the OptFlux framework allows the use of different model formats and the integration with complementary methods for phenotype simulation and visualization of the results. Moreover, the flux ratio constraints can be obtained from previous calculations in MiNeRAl, or manually defined by the user. The first option provides a straightforward way to integrate both applications in a ME workflow

Automatic control system for an oil-hydraulic actuator of a scissor lift

Lifting equipment’s have the purpose to lift goods within their safe working load and design rules specified in standards. However, some applications require additional care regarding handling the load when this care is out of the standard’s specifications. This paper presents the control and supervision system development of a scissor lift table, which should ensure, during its motion, that the vertical speed is constant. This lift table is working alongside a system for handling boxes composed by 3 entry conveyors and 1 exit conveyor. In this work, it was carried out the study of the direct and inverse kinematics to obtain the equations of position, speed and force for the oil-hydraulic actuator and the applicability of Denavit-Hartenberg’s algorithm for these equations. It was proposed a hydraulic circuit, with the selection of the main hydraulic components and the design of the oil-hydraulic actuator (a cylinder) with the magnetostrictive transducer as well. A programmable logical controller was selected, as well as the sensors and actuators for the conveyor system and a program was developed which allows to automatically control the system. The lift table’s velocity control is done by equations which define an oil flow profile of the hydraulic cylinder, which ensures a constant vertical speed of the lift table. To improve the control of the system, initial and final flow ramps were added to the equations, with reduced oil flow at the target height. It was observed that the use of Denavit-Hartenberg’s algorithm revealed to be limited, on which it was necessary to use other calculation methods to obtain the equations of speed and force. However, the proposed oil-hydraulic circuit, as well as the developed speed control, allow the control of the lift table’s position and speed.info:eu-repo/semantics/publishedVersio