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4. Optimal Noise in a Stochastic Model for Local Search

Author

Noetel, J., Freitas, V. L. S., Macau, E. E. N., and Schimansky-Geier, L.

Subjects
Condensed Matter - Statistical Mechanics, Physics - Biological Physics
Abstract

We develop a prototypical stochastic model for local search around a given home. The stochastic dynamic model is motivated by experimental findings of the motion of a fruit fly around a given spot of food but shall generally describe local search behavior. The local search consists of a sequence of two epochs. In the first the searcher explores new space around the home whereas it returns to the home during the second epoch. In the proposed two dimensional model both tasks are described by the same stochastic dynamics. The searcher moves with constant speed and its angular dynamics is driven by a symmetric {\alpha}-stable noise source. The latter stands for the uncertainty to decide the new direction of motion. The main ingredient of the model is the nonlinear interaction dynamics of the searcher with its home. In order to determine the new heading direction, the angles of its position to the home and of the heading vector need to be known. A bound state to the home is realized by a permanent switch of a repulsive and attractive forcing of the heading direction from the position direction corresponding to search and return epochs. Our investigation elucidates the analytic tractability of the deterministic and stochastic dynamics. The noise enables a faster finding of a target distinct from the home with optimal intensity. This optimal situation is related to the noise dependent relaxation time. It is uniquely defined for all {\alpha} and distinguishes between the stochastic dynamics before and after its value. For times large compared to this we derive the corresponding Smoluchowski equation and find diffusive spreading of searcher in the space. As result of its simplicity the model aims to reproduce the local search behavior of simple units during their exploration of surrounding space and their quasi-periodic return to a home.

Published
2018
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5. Search and Return Model for Stochastic Path Integrators

Author

Noetel, J., Freitas, V. L. S., Macau, E. E. N., and Schimansky-Geier, L.

Subjects
Condensed Matter - Statistical Mechanics, Physics - Biological Physics
Abstract

We extend a recently introduced prototypical stochastic model describing uniformly the search and return of objects looking for new food sources around a given home. The model describes the kinematic motion of the object with constant speed in two dimensions. The angular dynamics is driven by noise and describes a "pursuit" and "escape" behavior of the heading and the position vectors. Pursuit behavior ensures the return to the home and the escaping between the two vectors realizes exploration of space in the vicinity of the given home. Noise is originated by environmental influences and during decision making of the object. We take symmetric {\alpha}-stable noise since such noise is observed in experiments. We now investigate for the simplest possible case, the consequences of limited knowledge of the position angle of the home. We find that both noise type and noise strength can significantly increase the probability of returning to the home. First, we review shortly main findings of the model presented in the former manuscript. These are the stationary distance distribution of the noise driven conservative dynamics and the observation of an optimal noise for finding new food sources. Afterwards, we generalize the model by adding a constant shift {\gamma} within the interaction rule between the two vectors. The latter might be created by a permanent uncertainty of the correct home position. Non vanishing shifts transform the kinematics of the searcher to a dissipative dynamics. For the latter we discuss the novel deterministic properties and calculate the stationary spatial distribution around the home.

Published
2018
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7. AB1115 VITAMIN D SUPPLEMENTATION PRESENTS A POSITIVE EFFECT ON MEMORY BUT NO EFFECT ON ANXIOUS-DEPRESSIVE BEHAVIOR IN A PRISTANE-INDUCED LUPUS MOUSE MODEL

Author

Karnopp, T. E., primary, Flores Chapacais, G., additional, Gasparini, M. L., additional, Garcia Dos Santos, N., additional, Da Silva Freitas, V., additional, Piccoli, M., additional, Leite DI Domenico, A., additional, Denardi Dória, L., additional, Pereira de Souza, N. M., additional, Correa Freitas, E., additional, Rieger, A., additional, and Monticielo, O. A., additional

Published
2024
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14. Potential of nature-based solutions to reduce antibiotics, antimicrobial resistance, and pathogens in aquatic ecosystems. a critical review

Author

Pastor-López, E.J., Escolà, M., Kisielius, V., Arias, C.A., Carvalho, P.N., Gorito, A.M., Ramos, S., Freitas, V., Guimarães, L., Almeida, C.M.R., Müller, J.A., Küster, Eberhard, Kilian, R.M., Diawara, A., Ba, S., Matamoros, V., Pastor-López, E.J., Escolà, M., Kisielius, V., Arias, C.A., Carvalho, P.N., Gorito, A.M., Ramos, S., Freitas, V., Guimarães, L., Almeida, C.M.R., Müller, J.A., Küster, Eberhard, Kilian, R.M., Diawara, A., Ba, S., and Matamoros, V.

Abstract

This comprehensive scientific review evaluates the effectiveness of nature-based solutions (NBS) in reducing antibiotics (ABs), combating antimicrobial resistance (AMR), and controlling pathogens in various aquatic environments at different river catchment levels. It covers conventional and innovative treatment wetland configurations for wastewater treatment to reduce pollutant discharge into the aquatic ecosystems as well as exploring how river restoration and saltmarshes can enhance pollutant removal. Through the analysis of experimental studies and case examples, the review shows NBS's potential for providing sustainable and cost-effective solutions to improve the health of aquatic ecosystems. It also evaluates the use of diagnostic indicators to predict NBS effectiveness in removing specific pollutants such as ABs and AMR. The review concludes that NBS are feasible for addressing the new challenges stemming from human activities such as the presence of ABs, AMR and pathogens, contributing to a better understanding of NBS, highlighting success stories, addressing knowledge gaps, and providing recommendations for future research and implementation.

Published
2024

17. Enhancing the Potential of Light Perovskites: A Study on Fe-Doped CaTiO3 Compounds for Advanced Technological Applications.

Author

Barbieri, F., Dias, L. C., Endo, K. M., Mazur, M., Rosso, J. M., Tominaga, T. T., Bonadio, T. G. M., Dias, G. S., Ferrreira., A. C., Silva, D. M., Cótica, L. F., Santos, I. A., Eiras, J. A., and Freitas, V. F.

Abstract

This study explores the synthesis and characterization of Fe-doped CaTiO3 compounds via the Pechini method, focusing on their structural, magnetic, and electrical properties. Notably, a previously unreported magnetic property is observed in the Fe-doped CaTiO3 compound. Despite significant structural distortions, ferroelectric polarization is identified using the Geometrical Polarization Approach (GPA), indicating its emergent nature. These distortions are attributed to robust chemical bonds between ionic O1−2 and Ti+4 sites, as evidenced by electronic density maps. This research sheds light on the potential of these materials for various technological applications. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Magnetism and the magnetocaloric effect in amorphous metals formed by the series Gd10-xNix.

Author

Nóbrega, E. P., Freitas, V. L. O., Costa, S. S., Alho, B. P., Ribeiro, P. O., de Sousa, V. S. R., and von Ranke, P. J.

Subjects
MAGNETOCALORIC effects, METALLIC glasses, MAGNETIC transitions, METALWORK, MAGNETISM, MEAN field theory, MAGNETIC entropy
Abstract

In this work, we will study magnetism and the magnetocaloric effect in amorphous ferromagnets formed by the series G d 100 - x N i x , where x = 29 , 32, 35 and 37. To calculate the magnetocaloric potential and magnetizations as a function of temperature and applied magnetic field, we will use the mean-field theory with the Handrich approximation to deal with the lack of structural order in amorphous systems. We seek to understand how the replacement of Gd by Ni influences the magnetocaloric properties of the binary alloys formed. The present study is important for the possible practical applications of the magnetocaloric effect and for understanding the microscopic mechanisms involved in the magnetic phase transitions of amorphous systems. [ABSTRACT FROM AUTHOR]

Published
2024
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26. EDUCAÇÃO, FORMAÇÃO DOCENTE E CULTURA: diálogos na perspectiva da teoria das representações sociais

Author

SILVA, R. D., primary, FREITAS, V. L. C., additional, SOUSA, J. M., additional, NASCIMENTO, Ana Michele A., additional, SILVA, A. M., additional, SILVA, C. V. R., additional, SILVA, M. T. L., additional, LIMA, M. V. G., additional, ABRANCHES, S. P., additional, SILVA, S. B., additional, MAIA, Tiago Macedo Bezerra, additional, SILVA, V. C., additional, SILVA, V. M., additional, and SILVA, W. M. F., additional

Published
2019
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33. OC33 Chromatographic approaches to study pine nut skin: exploitation of its composition and bioactivities

Author

Silva, Soraia P., Colunga, Alondra, Roupar, Dalila, Salvador, Andreia Filipa Ferreira, Nobre, Clarisse, Reis, S. F., Freitas, V., Coimbra, M. A., Coelho, E., and Universidade do Minho

Abstract

Pine nut skin (PNS) is an unexploited and uncharacterized by-product recovered during pine nut processing. The exploitation of by-products as sources of valuable compounds agrees with the current demand for the reduction of waste, and a transition to more sustainable production and consumption1. Therefore, PNS characterization and bioactive potentialities were assessed. The utilization of several chromatographic techniques allowed the characterization of PNS phenolic compounds (HPLC-DAD-UV and HPLC-DAD-ESI-MSn), and the carbohydrates quantification and structural characterization, after specific derivatization (GC-FID and GC-MS). PNS subcritical water extraction using microwave was optimized and the obtained extracts, separated into low-molecularweight (rich in phenolic compounds) and high-molecular-weight (rich in carbohydrates), were evaluated regarding their digestibility and prebiotic activity. The prebiotic potential was assessed by quantifying the short-chain fatty acids (HPLC-UV) produced after the in vitro faecal fermentation. HPLC-DAD-ESI-MSn allowed to identify PNS phenolic compounds, namely protocatechuic, p-coumaric, and caffeic acids, while HPLC-DAD-UV enabled the monomers identification of proanthocyanidins ((epi)catechins) and hydrolysable tannins (protocatechuic acid), after acid methanolysis. GC techniques allowed to disclose the polysaccharides structures (xyloglucans and pectic polysaccharides) and their degradation by microbiota. The fermentation of both extracts rich in phenolic compounds and rich in polysaccharides resulted in an increased production of acetic, propionic, and butyric acids when compared to the commercial prebiotic inulin, proposing these PNS extracts as prebiotic agents., The work was supported through the projects UIDB/50006/2020 and UIDP/50006/2020, funded by FCT/MCTES through national funds. Soraia P. Silva, Alondra González and Dalila Roupar thank FCT/MCTES and ESF through NORTE 2020 for their PhD grants (ref. SFRH/BD/136471/2018, SFRH/BD/06268/2021 and SFRH/DB/139884/2018 respectively). Elisabete Coelho thanks the research contract (CDL-CTTRI-88-ARH/2018 – REF. 049-88-ARH/2018) funded by national funds (OE), through FCT, in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. Clarisse Nobre acknowledges FCT for the assistant research contract 2021.01234.CEECIND., info:eu-repo/semantics/publishedVersion

Published
2022

39. Wine

Author

Fernandes, I., primary, Pérez-Gregorio, R., additional, Soares, S., additional, Mateus, N., additional, and De Freitas, V., additional

Published
2017
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40. List of Contributors

Author

Abriouel, H., primary, Aguilera, Y., additional, Amigo, L., additional, Beena, D.J., additional, Benítez-Páez, A., additional, Benítez, V., additional, Benomar, N., additional, Bou, R., additional, Cerezo, A.B., additional, Chung, S.H., additional, Ciesarová, Z., additional, Coda, R., additional, Cofrades, S., additional, Coton, M., additional, Curiel, J.A., additional, Daniel, N., additional, De Freitas, V., additional, de las Rivas, B., additional, Diana, M., additional, Escalante, A., additional, Esteban-Torres, M., additional, Fernandes, I., additional, Fernandez, M.A., additional, Figueroa, L.M., additional, Frias, J., additional, Gálvez, A., additional, Garcia-Parrilla, M.C., additional, Gobbetti, M., additional, Gómez-Guillén, M.C., additional, González-SanJosé, M.L., additional, Gürsoy, O., additional, Gutiérrez-Uribe, J.A., additional, Hernández-Ledesma, B., additional, Ismail, B., additional, Jeong, J.-K., additional, Jiménez-Colmenero, F., additional, Karovičová, J., additional, Kesenkaş, H., additional, Kim, D.-H., additional, Kim, H.-Y., additional, Kim, M., additional, Knapp, C.W., additional, Kohajdová, Z., additional, Landete, J.M., additional, Le Barz, M., additional, López de Felipe, F., additional, López-Caballero, M.E., additional, López-Expósito, I., additional, Magala, M., additional, Mani, V., additional, Marette, A., additional, Martín-Cabrejas, M.A., additional, Martín-del-Campo, S.T., additional, Martínez-Álvarez, O., additional, Martinez-Villaluenga, C., additional, Martín, J.F., additional, Mas, A., additional, Mateus, N., additional, Mikušová, L., additional, Ming, L.C., additional, Miralles, B., additional, Montero, P., additional, Muñoz, R., additional, Nampoothiri, K.M., additional, Özbaş, H., additional, Park, K.-Y., additional, Patel, S., additional, Peñas, E., additional, Peres, C., additional, Peres, C.M., additional, Pérez-Gregorio, R., additional, Picard-Deland, É., additional, Quílez, J., additional, Reiter, R.J., additional, Reverón, I., additional, Rizzello, C.G., additional, Rodríguez, H., additional, Rodríguez, P.M., additional, Ryan, E.P., additional, Santamaría, L., additional, Sanz, Y., additional, Schmid, A., additional, Shukla, S., additional, Simon Sarkadi, L., additional, Soares, S., additional, Surma, M., additional, Torija, M.J., additional, Troncoso, A.M., additional, Valls-Bellés, V., additional, Vasanthakumari, D.S., additional, Walther, B., additional, Wilburn, J.R., additional, Xavier Malcata, F., additional, Zielińska, D., additional, and Zieliński, H., additional

Published
2017
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42. O-032 Primary human endothelial and stromal cells from the uterine endometrium co-cultured in vitro in a 3D-system as a model to study the physiopathology of endometriosis

Author

Lorenzon, A, primary, Guedes, C B, additional, Borbely, A U, additional, Cardoso, E C, additional, Corrêa-Silva, S, additional, Bonetti, T C, additional, Serafini, P C, additional, Motta, E L, additional, Freitas, V M, additional, Myung, L H J, additional, Abraão, M S, additional, and Bevilaqua, E, additional

Published
2022
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44. On the superparamagnetic behavior of BiFeO3‐PbTiO3 nanoparticles.

Author

Freitas, V. F., Thomen, D. M. N., Miyahara, R. Y., Bonadio, T. G. M., Silva, D. M., Rosso, J. M., Dias, G. S., Cótica, L. F., Santos, I. A., Yokaichiya, F., de Medeiros, S. N., Eiras, J. A., Guo, R., and Bhalla, A. S.

Subjects
*SUPERPARAMAGNETIC materials, *MAGNETIC nanoparticles, *CURVE fitting, *X-ray diffraction, *MAGNETIZATION, *METAL nanoparticles, *NANOPARTICLES
Abstract

In this work, the nanostructuration effects on the physical properties of pure and La doped (0.6)BiFeO3‐(0.4)PbTiO3 magnetoelectric nanoparticles were investigated. An exotic magnetic response, mimicking a superparamagneticlike behavior that raised the magnetization to levels never reported before for these materials, is clearly observed. Another important change associated with the nanostructuration is observed in the symmetry of the perovskite-structured materials, which changes from a tetragonal to a rhombohedral one. Transmission electron microscopic and X-ray diffraction results (investigated by the Debye-Scherrer method) revealed uniform nanoparticles of spherical shape, average particle sizes close to 5 nm and with a single structural domain (only one crystallite per particle). The pronounced increase (∼20 times) in the magnetization response of the nanoparticles, compared to microparticle ones, is observed in magnetization curves. A magnetic semiempirical phenomenological model, where noninteracting single-domain magnetic nanoparticles are considered, is used to fit the magnetization curves, revealing the almost absence of surface effects in a typical superparamagneticlike behavior. All these aspects pointing to a material with immense potential for practical applications in spintronics and magnetoelectronics. [ABSTRACT FROM AUTHOR]

Published
2019
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45. Sacculina carcini impact on energy content of the shore crab Carcinus maenas L.

Author

Campos, J., Ribas, F., Bio, A., Freitas, V., Souza, A.T., van der Veer, H.W., Campos, J., Ribas, F., Bio, A., Freitas, V., Souza, A.T., and van der Veer, H.W.

Abstract

The impact of Sacculina carcini infection on the nutritional status of the shore crab Carcinus maenas was investigated in the western Dutch Wadden Sea for a period of 20 months. About 3.3% of thepopulation was sacculinized, i.e. externally infected with S. carcini and only 0.7% presented scars of previous infection. The results of mixed linear models showed that sacculinized and non-sacculinized crabs had similar morphometric condition, while the energy density of parasitized crabs (externa excluded) was significantly reduced by about 4.3% overall, and by up to 5.8% in crabs under 40 mm carapace width. However, when Sacculina externa was included in the energy determinations, the difference in energy density decreased to 1.2%, while total energy content of the pair infected crab-parasite including externa was 30.8% higher than non-sacculinized crabs of similar size. The total energy content of ovigerous females (eggs included) was even higher, near doubling the energy of similar-sized crabs. The same way, total energy content of Sacculina externa was about 4 times lower than total energy of egg mass. The results suggest that the rhizocephalan parasite is efficient in consuming the energy that the host may allocate for growth and maintenance, but require future studies to disentangle the impact of the degree of internal infection and the implications for the dynamics of the population.

Published
2022

46. Body condition and energy content of the shore crab Carcinus maenas L. in a temperate coastal system: the cost of barnacle epibiosis

Author

Campos, J., Ribas, F., Bio, A., Freitas, V., Souza, A.T., van der Veer, H.W., Campos, J., Ribas, F., Bio, A., Freitas, V., Souza, A.T., and van der Veer, H.W.

Abstract

The impact of barnacle epibionts on the condition of the shore crab Carcinus maenas was studied for the western Wadden Sea population. Approximately 39% of the crabs were fouled with the barnacle Balanus crenatus. Although the morphological Fulton’s K condition decreased by 5.8% in fouled crabs, Linear Mixed-Effects Models (LMM) showed that only the energetic condition of the crabs was significantly affected by fouling. The energy density of fouled crabs was consistently poorer (4.1% in AFDW; 8.7% in dry weight) than that of non-fouled crabs, especially in females and green forms in dry weight (12.8% and 11.4% reduction, respectively). Cumulative infection with Sacculina carcini, detected in 4.5% of the fouled crabs, additionally reduced by 14.3% the energy density in dry weight and almost to half of the total energy of the fouled crabs. Impacts of energy density reduction on crabs’ growth and reproduction are discussed.

Published
2022

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