5,257 research outputs found
Cosmic voids in modified gravity scenarios
Modified gravity (MG) theories aim to reproduce the observed acceleration of
the Universe by reducing the dark sector while simultaneously recovering
General Relativity (GR) within dense environments. Void studies appear to be a
suitable scenario to search for imprints of alternative gravity models on
cosmological scales. Voids cover an interesting range of density scales where
screening mechanisms fade out, which reaches from a density contrast close to their centers to close to their
boundaries. We present an analysis of the level of distinction between GR and
two modified gravity theories, the Hu-Sawicki and the symmetron theory.
This study relies on the abundance, linear bias, and density profile of voids
detected in n-body cosmological simulations. We define voids as connected
regions made up of the union of spheres with a {\it \textup{mean}} density
given by , but disconnected from any
other voids. We find that the height of void walls is considerably affected by
the gravitational theory, such that it increases for stronger gravity
modifications. Finally, we show that at the level of dark matter n-body
simulations, our constraints allow us to distinguish between GR and MG models
with and . Differences of best-fit values for
MG parameters that are derived independently from multiple void probes may
indicate an incorrect MG model. This serves as an important consistency check.Comment: 15 pages, 12 figure
Momentum Space Regularizations and the Indeterminacy in the Schwinger Model
We revisited the problem of the presence of finite indeterminacies that
appear in the calculations of a Quantum Field Theory. We investigate the
occurrence of undetermined mathematical quantities in the evaluation of the
Schwinger model in several regularization scenarios. We show that the
undetermined character of the divergent part of the vacuum polarization tensor
of the model, introduced as an {\it ansatz} in previous works, can be obtained
mathematically if one introduces a set of two parameters in the evaluation of
these quantities. The formal mathematical properties of this tensor and their
violations are discussed. The analysis is carried out in both analytical and
sharp cutoff regularization procedures. We also show how the Pauli Villars
regularization scheme eliminates the indeterminacy, giving a gauge invariant
result in the vector Schwinger model.Comment: 10 pages, no figure
Editorial: Special Issue contributed by the 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008
The 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008,
was held in Braga, Portugal, from the 4th to the 6th of September, 2008. The conference was
jointly organized by the University of Minho, the “Ordem dos Engenheiros,” and the Institute for
Biotechnology and Bioengineeing, with the support of “Sociedade Portuguesa de Qu´ımica” and
“Sociedade Portuguesa de Biotecnologia”.
The CHEMPOR series traditionally brings together both young and established researchers and
end users to discuss recent developments in different areas of Chemical Engineering. The scope
of this edition was extended to Biological Engineering research. One of the major core areas
of the conference program was life quality, due to the importance that Chemical and Biological
Engineering plays in this area. “Integration of Life Sciences & Engineering” and “Sustainable
Process-Product Development through Green Chemistry” were two of the leading themes with papers
addressing such important issues. This was complemented with additional leading themes including
“Advancing the Chemical and Biological Engineering Fundamentals,” “Multi-Scale and/or
Multi-Disciplinary Approach to Process-Product Innovation”, “Systematic Methods and Tools for
Managing the Complexity”, and “Educating Chemical and Biological Engineers for Coming Challenges.”
Papers contributed for this special issue represent a good sample of the important themes
that were addressed.
This special issue presents a set of fifteen selected research papers, which have undergone the
peer-review process of Chemical Product and Process Modeling journal. We wish to thank the authors
who have contributed to yield a high scientific standard to this special issue. We also extend
our gratefulness to all reviewers, through their dedicated efforts, having assisted us in this task.Uminho -Universidade do Minh
Application of image analysis techniques in biotechnology
Image analysis is commonly used nowadays in a wide range of
applications due to the development of faster computers,
advanced frame grabbers, and sophisticated software.
Although the availability of commercial sophisticated software
some efforts have been made at CEB-IBQF in software
development using MATLAB programming environment. This
programming approach permits to tailor the software to our
specific needs. In-house software currently in use and
development include: automatic differentiation of flocs and
granules through fractal dimension; monitoring methanogenic
auto-fluorescence; determination of the reduction in mobility of
ciliates exposed to toxics; automatic quantification of
filamentous bacteria; automatic counting of viable/non-viable
yeasts by epifluorescence microscopy with acridine orange as
dying agent.
Other developments cover automatic determination of the
number of yeast flocs and their size distribution, dynamics of
bacterial adhesion, estimation of the tortuosity of porous media,
and automatic detection, counting of ink spots in recycled
paper simultaneous and monitoring of lactic acid bacteria and
yeast during Vinho Verde fermentation using phase contrast
microscopy coupled to image analysis
Description and molecular phylogeny of a new and one known needle nematode of the genus Paralongidorus (Nematoda: Longidoridae) from grapevine in Portugal
A new and a known longidorid nematode, Paralongidorus lusitanicus n. sp. and Paralongidorus plesioepimikis, are described and illustrated from populations extracted from soil associated with grapevine (Vitis vinifera L.) from Escaroupim and Pó (central-Western Portugal), respectively. The new needle nematode P. lusitanicus n. sp. is characterised by a very large body size (8072–12,022 μm), an expanded and rounded lip region, ca 30 μm wide, with a clear constriction followed by a depression posterior to the amphidial aperture, amphidial fovea very large (11.0–19.0 μm), stirrup-shaped, with conspicuous slit-like aperture as shown in scanning electron microscopy studies, a very long and flexible odontostyle (180.0–223.0 μm), guiding ring located at 28.0–41.5 μm from anterior end, vulva anterior to the mid-body (34–41%), a dorsally convex-conoid tail with rounded terminus (29–42 μm long), bearing two or three pairs of caudal pores and males common (ratio 1:1.6 females) with spicules ca 80 μm long. Morphological and morphometric traits for P. plesioepimikis fit well with the original description, and is reported for the first time in Portugal. Integrative diagnosis of both species was completed with molecular data obtained using D2-D3 expansion segments of 28S rDNA, ITS1-rDNA and partial 18S–rDNA. The phylogenetic relationships of these species with other Paralongidorus spp. using these three molecular markers indicated that P. lusitanicus n. sp. clustered together with other Paralongidorus spp. forming a sister clade with P. plesioepimikis, both of them sharing a large body, long odontostyle, an anteriorly located vulva and an expanded and rounded lip region with a clear constriction followed by a depression posterior to the amphidial aperture
Anisakis infection in allis shad, Alosa alosa (Linnaeus, 1758), and twaite shad, Alosa fallax (Lacépède, 1803), from Western Iberian Peninsula Rivers : zoonotic and ecological implications
Acknowledgments The authors would like to thank M. N. Cueto and J.M. Antonio (ECOBIOMAR) for their excellent technical support and also Rodrigo López for making the map of the study area. We also thank the personal of the Vigo IEO, for providing information about shad captures at sea collected on the basis of national program (AMDES) included in the European Data Collection Framework (DCF) project. We are also grateful to Comandancia Naval de Tui for providing fishing data. M. Bao is supported by a PhD grant from the University of Aberdeen and also by financial support of the contract from the EU Project PARASITE (grant number 312068). This study was partially supported by a PhD grant from the Portuguese Foundation for Science and Technology (FCT) SFRH/BD/44892/2008) and partially supported by the European Regional Development Fund (ERDF) through the COMPETE—Operational Competitiveness Programme and national funds through Foundation for Science and Technology (FCT), under the project BPEst-C/MAR/ LA0015/2013. The authors thank the staff of the Station of Hydrobiology of the USC BEncoro do Con^ due their participation in the surveys. This work has been partially supported by the project 10PXIB2111059PR of the Xunta de Galicia and the project MIGRANET of the Interreg IV BSUDOE (South-West Europe) Territorial Cooperation Programme (SOE2/P2/E288). D.J. Nachón is supported by a PhD grant from the Xunta de Galicia (PRE/2011/198)Peer reviewedPostprin
Image Analysis and Multiphase Bioreactors
The applications of visualisation and image analysis to bioreactors can be found in two main areas: the characterisation of biomass (fungi, bacteria, yeasts, animal and plant cells, etc), in terms of size, morphology and physiology, that is the far most developed, and the characterisation of the multiphase behaviour of the reactors (flow patterns, velocity fields, bubble size and shape distribution, foaming), that may require sophisticated visualisation techniques
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