1,732 research outputs found
Non-local Thirring model at finite-temperature
We extend a recently proposed non-local and non-covariant version of the
Thirring model to the finite-temperature case. We obtain a completely bosonized
expression for the partition function, describing the thermodynamics of the
collective modes which are the underlying excitations of this system. From this
result we derive closed formulae for the free-energy, specific-heat, two-point
correlation functions and momentum distribution, as functionals of
electron-electron coupling potentials.Comment: 23 pages, latex, no figure
Capacitance Measurements for Subcell Characterization in Multijunction Solar Cells.
On this paper we present an alternative way to analyze de electronic properties of each subcell from the complete device. By illuminating the cell with light sources which energy is near one of the subcell bandgaps, it is possible to “erase” the presence of such subcell on the CV curve. The main advantages of this technique are that it is not destructive, it can be measured on the complete cell so can be easily implemented as a diagnostic technique for controlling electronic deviations
The Tomato Processing Industry in Portugal
Portugal is a major producer of tomatoes for processing. Is export industry now ranks 4th worldwide; before the strongly protectionist European Common Market policy initiated in the early 1970s it ranked 3rd. The culture of tomatoes for processing in irrigated areas of Portugal is favored by the dry, warm summer that characterizes Mediterranean climates. In addition the summer in Portugal is not too hot for a good tomato set
Rasgos sedimentarios de los conglomerados miocénicos del borde noreste de la Depresión de Granada
Este trabajo da una primera interpretación sedimentaria y una reconstrucción paleogeográfica
de los materiales conglomeráticos neógenos de parte de la Depresión de Granada.
El modelo sedimentario propuesto consiste en abanicos aluviales que penetran en medio
marino. En una fase posterior, se establece un régimen fluvial que desemboca en zonas lacustres,
eventualmente evaporÍticas.
[ABSTRACT]
This paper offers a first sedimentary interpretation aod a paleogeographic reconstruction
for the neogenic conglomerates in a part of Granada Basin. The proposed sedimentary ruodel
consists on alluvial fans going into marine environment. Later, a braided fluviatile pattern
connected downstream with lacllstrine areas with episodic evaporite deposits establishes in
this place
LISA, binary stars, and the mass of the graviton
We extend and improve earlier estimates of the ability of the proposed LISA
(Laser Interferometer Space Antenna) gravitational wave detector to place upper
bounds on the graviton mass, m_g, by comparing the arrival times of
gravitational and electromagnetic signals from binary star systems. We show
that the best possible limit on m_g obtainable this way is ~ 50 times better
than the current limit set by Solar System measurements. Among currently known,
well-understood binaries, 4U1820-30 is the best for this purpose; LISA
observations of 4U1820-30 should yield a limit ~ 3-4 times better than the
present Solar System bound. AM CVn-type binaries offer the prospect of
improving the limit by a factor of 10, if such systems can be better understood
by the time of the LISA mission. We briefly discuss the likelihood that radio
and optical searches during the next decade will yield binaries that more
closely approach the best possible case.Comment: ReVTeX 4, 6 pages, 1 figure, submitted to Phys Rev
Improving the Accuracy of a Two-Stage Algorithm in Evolutionary Product Unit Neural Networks for Classification by Means of Feature Selection
This paper introduces a methodology that improves the accuracy
of a two-stage algorithm in evolutionary product unit neural networks
for classification tasks by means of feature selection. A couple
of filters have been taken into consideration to try out the proposal.
The experimentation has been carried out on seven data sets from the
UCI repository that report test mean accuracy error rates about twenty
percent or above with reference classifiers such as C4.5 or 1-NN. The
study includes an overall empirical comparison between the models obtained
with and without feature selection. Also several classifiers have
been tested in order to illustrate the performance of the different filters
considered. The results have been contrasted with nonparametric statistical
tests and show that our proposal significantly improves the test
accuracy of the previous models for the considered data sets. Moreover,
the current proposal is much more efficient than a previous methodology
developed by us; lastly, the reduction percentage in the number of inputs
is above a fifty five, on average.MICYT TIN2007-68084-C02-02MICYT TIN2008-06681-C06-03Junta de Andalucía P08-TIC-374
Dietary fiber, mineral elements profile and macronutrients composition in different edible parts of Opuntia microdasys (Lehm.) Pfeiff and Opuntia macrorhiza (Engelm.)
Nowadays, we are living in the era of functional foods. People are constantly seeking for new healthier food products, mainly derived from plants, with bioactive components such as fiber and/or mineral elements, in suitable and healthy ratios. Cactus (Opuntia spp.), which includes more than 1500 species, presents high potential to be considered as a functional food, as it was revealed by the phytochemical profiles and antioxidant activity previously demonstrated in different botanical parts of Opuntia microdasys (Lehm.) Pfeiff and Opuntia macrorhiza (Engelm.). In this follow-up work, morphological characters, nutritional composition, and particularly fiber and mineral elements profiles of these two species were characterized in the cladodes, pulp and seeds. Most of these parameters were also studied in their juice. Both species presented similar chemical profiles, but each of the different studied botanical parts presented great differences, as revealed by principal component analysis. Accordingly, the obtained results reinforce Opuntia spp. as a potential functional food, indicating also the botanical parts with highest adequacy to act as source of a specific constituent.The authors are grateful to Fundação para a Ciência e a Tecnologia (FCT, Portugal) for financial support to CIMO (strategic project PEst-OE/AGR/UI0690/2011) and ALIMNOVA research group (UCM-GR35/10A). J.C.M. Barreira thanks FCT, POPH-QREN and FSE for his grant (SFRH/BPD/72802/2010). L. Barros thanks “Compromisso para a Ciência 2008” for her contract
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