3,640 research outputs found
Dynamic modelling to describe the effect of plant extracts and customised starter culture on Staphylococcus aureus survival in goat's raw milk soft cheese
This study characterises the effect of a customised starter culture (CSC) and plant extracts (lemon balm, sage, and spearmint) on Staphylococcus aureus (SA) and lactic acid bacteria (LAB) kinetics in goat’s raw milk soft cheeses. Raw milk cheeses were produced with and without the CSC and plant extracts, and analysed for pH, SA, and LAB counts throughout ripening. The pH change over maturation was described by an empirical decay function. To assess the effect of each bio-preservative on SA, dynamic Bigelow-type models were adjusted, while their effect on LAB was evaluated by classical Huang models and dynamic Huang–Cardinal models. The models showed that the bio-preservatives decreased the time necessary for a one-log reduction but generally affected the cheese pH drop and SA decay rates (logDref=0.621–1.190 days; controls: 0.796–0.996 days). Spearmint and sage extracts affected the LAB specific growth rate (0.503 and 1.749 ln CFU/g day−1; corresponding controls: 1.421 and 0.806 ln CFU/g day−1), while lemon balm showed no impact (p > 0.05). The Huang–Cardinal models uncovered different optimum specific growth rates of indigenous LAB (1.560–1.705 ln CFU/g day−1) and LAB of cheeses with CSC (0.979–1.198 ln CFU/g day−1). The models produced validate the potential of the tested bio-preservatives to reduce SA, while identifying the impact of such strategies on the fermentation process.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2020). They are also grateful to the EU PRIMA program and FCT for funding the ArtiSaneFood project (PRIMA/0001/2018). This study was supported by FCT under the scope of the strategic funding of the UIDB/04469/2020 unit and the BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte. B.N. Silva acknowledges the financial support provided by FCT through the Ph.D. grant SFRH/BD/137801/2018.info:eu-repo/semantics/publishedVersio
Multi-objective evolutionary optimization for dimensionality reduction of texts represented by synsets
Despite new developments in machine learning classification techniques, improving the accuracy of spam filtering is a difficult task due to linguistic phenomena that limit its effectiveness. In particular, we highlight polysemy, synonymy, the usage of hypernyms/hyponyms, and the presence of irrelevant/confusing words. These problems should be solved at the pre-processing stage to avoid using inconsistent information in the building of classification models. Previous studies have suggested that the use of synset-based representation strategies could be successfully used to solve synonymy and polysemy problems. Complementarily, it is possible to take advantage of hyponymy/hypernymy-based to implement dimensionality reduction strategies. These strategies could unify textual terms to model the intentions of the document without losing any information (e.g., bringing together the synsets “viagra”, “ciallis”, “levitra” and other representing similar drugs by using “virility drug” which is a hyponym for all of them). These feature reduction schemes are known as lossless strategies as the information is not removed but only generalised. However, in some types of text classification problems (such as spam filtering) it may not be worthwhile to keep all the information and let dimensionality reduction algorithms discard information that may be irrelevant or confusing. In this work, we are introducing the feature reduction as a multi-objective optimisation problem to be solved using a Multi-Objective Evolutionary Algorithm (MOEA). Our algorithm allows, with minor modifications, to implement lossless (using only semantic-based synset grouping), low-loss (discarding irrelevant information and using semantic-based synset grouping) or lossy (discarding only irrelevant information) strategies. The contribution of this study is two-fold: (i) to introduce different dimensionality reduction methods (lossless, low-loss and lossy) as an optimization problem that can be solved using MOEA and (ii) to provide an experimental comparison of lossless and low-loss schemes for text representation. The results obtained support the usefulness of the low-loss method to improve the efficiency of classifiers.info:eu-repo/semantics/publishedVersio
Efeito de extratos de pimenta do gênero capsicum no controle da mela do feijoeiro (Rhizoctonia solani) in vivo.
O presente trabalho teve como objetivo testar 25 extratos aquosos de pimentas do gênero Capsicum, obtidos a partir de sementes (s), folhas (fo) e frutos (fr) das variedades: ? Bode Amarela?, ?de Gaúcho?, ?Peito-de-Moça?, ?Jurema?, ?Amarela?, ?Acerola?, ?Chifre de Gazela?, ?Carrapeta?, ?Mexicana Roxa Comprida?, ?Mexicana Roxa Pequena?, ?Dedo-de-Moça?, ?dos Desejos?, ?Pitanga Amarela?, ?Biquinho?, ?Síria?, ?Tororó?, ?Três Quinas? e ?Bode Vermelha?
Caracterização da ocorrência do moko da bananeira (Ralstonia solanacearum raça 2) nos municípios de Rondônia.
Este trabalho pretendeu determinar a real ocorrência do Moko da bananeirano estado de Rondônia, numa parceria da Embrapa Rondônia e a agência de defesa sanitária estadual IDARON, na qual se promoveu um levantamento amplo, realizado entre 2004 e 2012, em 34 municípios
Efeito de produtos alternativos no controle da mela do feijoeiro (Rhizoctonia solani) em campo.
Neste trabalho objetivou-se testar diferentes produtos alternativos para controle da mela em campo
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Observations of Past Lunar Landing Sites by the D-CIXS X-Ray Spectrometer on SMART-1
D-CIXS initial observations show a first unambiguous remote sensing of calcium in the lunar regolith. Data obtained are broadly consistent with current understanding of mare and highland composition. Ground truth is provided by the returned Apollo and Luna sample sets
Geodesic motion in the space-time of a cosmic string
We study the geodesic equation in the space-time of an Abelian-Higgs string
and discuss the motion of massless and massive test particles. The geodesics
can be classified according to the particles energy, angular momentum and
linear momentum along the string axis. We observe that bound orbits of massive
particles are only possible if the Higgs boson mass is smaller than the gauge
boson mass, while massless particles always move on escape orbits. Moreover,
neither massive nor massless particles can ever reach the string axis for
non-vanishing angular momentum. We also discuss the dependence of light
deflection by a cosmic string as well as the perihelion shift of bound orbits
of massive particles on the ratio between Higgs and gauge boson mass and the
ratio between symmetry breaking scale and Planck mass, respectively.Comment: 20 pages including 14 figures; v2: references added, discussion on
null geodesics extended, numerical results adde
Large atom number dual-species magneto-optical trap for fermionic 6Li and 40K atoms
We present the design, implementation and characterization of a dual-species
magneto-optical trap (MOT) for fermionic 6Li and 40K atoms with large atom
numbers. The MOT simultaneously contains 5.2x10^9 6Li-atoms and 8.0x10^9
40K-atoms, which are continuously loaded by a Zeeman slower for 6Li and a
2D-MOT for 40K. The atom sources induce capture rates of 1.2x10^9 6Li-atoms/s
and 1.4x10^9 40K-atoms/s. Trap losses due to light-induced interspecies
collisions of ~65% were observed and could be minimized to ~10% by using low
magnetic field gradients and low light powers in the repumping light of both
atomic species. The described system represents the starting point for the
production of a large-atom number quantum degenerate Fermi-Fermi mixture
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