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6,662 results on '"Ferreira R"'

1. Fujita exponent and blow-up rate for a mixed local and nonlocal heat equation

Author

Del Pezzo, L. and Ferreira, R.

Subjects
Mathematics - Analysis of PDEs
Abstract

In this paper we consider the blow-up problem for a mixed local-nonlocal diffusion operator, \[ u_t=a\Delta u -b(-\Delta)^s u+u^p. \] We show that the Fujita exponent is given by the nonlocal part, $p_F=1+2s/N$. We also determinate, in some cases, the blow-up rate., Comment: pages

Published
2024

2. Social dilemmas, network reciprocity and the small-world property

Author

Pereira, F. B., Ferreira, R. S., Alencar, D. S. M., Alves, T. F. A., Alves, G. A., Lima, F. W. S., and Macedo-Filho, A.

Subjects
Physics - Physics and Society
Abstract

We revisit two evolutionary game theory models, namely the Prisoner and the Snowdrift dilemmas, on top of small-world networks. These dynamics on networked populations (individuals occupying nodes of a graph) are mainly concerning on the competition between to cooperate or to defect, by allowing some process of revision of strategies. Cooperators avoid defectors by forming clusters in a process known as network reciprocity. This defense strategy is based on the fact that any individual interact only with its nearest neighbors. The minimum cluster, in turn, is formed by a set of three completely connected nodes and the bulk of these triplets is associated with the transitivity property of a network. Particularly, we show that the transitivity increases eventually assuming a constant behavior when observed as a function of the number of contacts of an individual. We investigate the influence of the network reciprocity on that transitivity increasing regime on the promotion of a cooperative behavior. The dynamics on small-world networks are compared with those random regular, and annealed networks, the later typically studied as the well-mixed approach. We observe that the Snowdrift Game converge to an annealed scenario as randonness and coordination number increase, whereas the Prisoner's Dilemma becomes more severe against the cooperative behavior under the regime of an increasing network reciprocity., Comment: 10 pages, 7 figures

Published
2024

3. Generalized Diffusive Epidemic Process with Permanent Immunity in Two Dimensions

Author

Carvalho, V. R., Alves, T. F. A., Alves, G. A., Alencar, D. S. M., Lima, F. W. S., Macedo-Filho, A., and Ferreira, R. S.

Subjects
Condensed Matter - Statistical Mechanics, Physics - Physics and Society
Abstract

We introduce the generalized diffusive epidemic process, which is a metapopulation model for an epidemic outbreak where a non-sedentary population of walkers can jump along lattice edges with diffusion rates $D_S$ or $D_I$ if they are susceptible or infected, respectively, and recovered individuals possess permanent immunity. Individuals can be contaminated with rate $\mu_c$ if they share the same lattice node with an infected individual and recover with rate $\mu_r$, being removed from the dynamics. Therefore, the model does not have the conservation of the active particles composed of susceptible and infected individuals. The reaction-diffusion dynamics are separated into two stages: (i) Brownian diffusion, where the particles can jump to neighboring nodes, and (ii) contamination and recovery reactions. The dynamics are mapped into a growing process by activating lattice nodes with successful contaminations where activated nodes are interpreted as infection sources. In all simulations, the epidemic starts with one infected individual in a lattice filled with susceptibles. Our results indicate a phase transition in the dynamic percolation universality class controlled by the population size, irrespective of diffusion rates $D_S$ and $D_I$ and a subexponential growth of the epidemics in the percolation threshold., Comment: 8 pages, 4 figures

Published
2024

4. Reconfigurable classifier based on spin torque driven magnetization switching in electrically connected magnetic tunnel junctions

Author

Lopez, A., Costa, D., Bohnert, T., Freitas, P. P., Ferreira, R., Barbero, I., Camarero, J., Leon, C., Grollier, J., and Romera, M.

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

A promising branch of neuromorphic computing aims to perform cognitive operations in hardware leveraging the physics of efficient and well-established nano-devices. In this work, we present a reconfigurable classifier based on a network of electrically connected magnetic tunnel junctions that categorizes information encoded in the amplitude of input currents through the spin torque driven magnetization switching output configuration. The network can be trained to classify new data by adjusting additional programming currents applied selectively to the junctions. We experimentally demonstrate that a network composed of three magnetic tunnel junctions can learn to classify spoken vowels with a recognition rate that surpasses the performance of software multilayer neural networks with the same number of trained parameters in this task. These results, obtained with the same nano-devices and working principle employed in industrial spin-transfer torque magnetic random-access memories (STT-MRAM), constitute an important step towards the development of large-scale neuromorphic networks based on well-established technology., Comment: To be published in Physical Review Applied. 13 pages, 4 figures

Published
2024

5. Critical Short-Time Behavior of Majority-Vote Model on Scale-Free Networks

Author

Alencar, D. S. M., Neto, J. F. S., Alves, T. F. A., Lima, F. W. S., Ferreira, R. S., Alves, G. A., and Macedo-Filho, A.

Subjects
Condensed Matter - Statistical Mechanics
Abstract

We discuss the short-time behavior of the majority vote dynamics on scale-free networks at the critical threshold. We introduce a heterogeneous mean-field theory on the critical short-time behavior of the majority-vote model on scale-free networks. In addition, we also compare the heterogeneous mean-field predictions with extensive Monte Carlo simulations of the short-time dependencies of the order parameter and the susceptibility. We obtained a closed expression for the dynamical exponent $z$ and the time correlation exponent $\nu_\parallel$. Short-time scaling is compatible with a non-universal critical behavior for $5/2 < \gamma < 7/2$, and for $\gamma \geq 7/2$, we have the mean-field Ising criticality with additional logarithmic corrections for $\gamma=7/2$, in the same way as the stationary scaling., Comment: 10 pages, 3 figures, 24 references

Published
2024

6. Estimating thresholds for asynchronous susceptible-infected-removed model on complex networks

Author

Alencar, D. S. M., Alves, T. F. A., Lima, F. W. S., Ferreira, R. S., Alves, G. A., and Macedo-Filho, A.

Subjects
Physics - Physics and Society
Abstract

We use the pair heterogeneous mean-field (PHMF) approximation for an asynchronous version of the susceptible-infected-removed (SIR) model to estimate the epidemic thresholds on complex quenched networks. Our results indicate an improvement compared to the heuristic heterogeneous mean-field theory developed for one vertex (HMF) when the dynamic evolves on top random regular and power-law networks. However, there is a slight overestimation of the transition point for the later network type. We also analyze scaling for random regular networks near the thresholds. For this region, collapses were shown at the subcritical and supercritical phases.

Published
2024

8. The LHCb upgrade I

Author

LHCb collaboration, Aaij, R., Abdelmotteleb, A. S. W., Beteta, C. Abellan, Abudinén, F., Achard, C., Ackernley, T., Adeva, B., Adinolfi, M., Adlarson, P., Afsharnia, H., Agapopoulou, C., Aidala, C. A., Ajaltouni, Z., Akar, S., Akiba, K., Albicocco, P., Albrecht, J., Alessio, F., Alexander, M., Albero, A. Alfonso, Aliouche, Z., Cartelle, P. Alvarez, Amalric, R., Amato, S., Amey, J. L., Amhis, Y., An, L., Anderlini, L., Andersson, M., Andreani, A., Andreianov, A., Andreotti, M., Andreou, D., Andrews, J. E., Anelli, M., Anjam, A., Ao, D., Archilli, F., Arnaud, K., Artamonov, A., Artuso, M., Ashby, J., Aslanides, E., Atzeni, M., Audurier, B., Rocha, D. Ayres, Perea, I. B Bachiller, Bachmann, S., Bachmayer, M., Back, J. J., Bailly-reyre, A., Rodriguez, P. Baladron, Balagura, V., Balbi, G., Baldini, W., Balla, A., Baltazar, M., Band, H., Leite, J. Baptista de Souza, Barbetti, M., Barclay, P., Barlow, R. J., Barsuk, S., Barter, W., Bartolini, M., Baryshnikov, F., Basels, J. M., Bassi, G., Baszczyk, M., Lopes, J. C. Batista, Batsukh, B., Battig, A., Bay, A., Beck, A., Becker, M., Bedeschi, F., Bediaga, I. B., Beigbeder-Beau, C., Beiter, A., Belin, S., Bellee, V., Belous, K., Belov, I., Belyaev, I., Benane, G., Bencivenni, G., Benettoni, M., Ben-Haim, E., Berezhnoy, A., Bernard, F., Bernet, R., Andres, S. Bernet, Berninghoff, D., Bernstein, H. C., Bertella, C., Bertolin, A., Betancourt, C., Betti, F., Bezshyiko, Ia., Bezshyyko, O., Bhasin, S., Bhom, J., Bian, L., Bieker, M. S., Biesuz, N. V., Billoir, P., Biolchini, A., Birch, M., Bishop, F. C. R., Bitadze, A., Bizzeti, A., Blago, M. P., Blake, T., Blanc, F., Blank, J. E., Blusk, S., Bobulska, D., Bochin, B., Boelhauve, J. A., Garcia, O. Boente, Boettcher, T., Bogdanova, G., Boiaryntseva, I., Boldyrev, A., Bolognani, C. S., Bolzonella, R., Bondar, N., Booth, M. J., Borgato, F., Borghi, S., Borsato, M., Borsuk, J. T., Boterenbrood, H., Bouchiba, S. A., Bowcock, T. J. V., Boyaryntsev, A., Boyer, A., Bozzi, C., Bradley, M. J., Braun, S., Rodriguez, A. Brea, Bregliozzi, G., Bridges, K., Briere, M. M. J., Brock, M., Brodski, M., Brodzicka, J., Gonzalo, A. Brossa, Brown, C., Brown, J., Brummitt, A. J., Brundu, D., Brunetti, L., Buda, L., Buonaura, A., Buonincontri, L., Burke, A. T., Burmistrov, L., Burr, C., Bursche, A., Butkevich, A., Butter, J. S., Buytaert, J., Byczynski, W., Cachemiche, J. P., Cadeddu, S., Cai, H., Caillet, A., Calabrese, R., Calefice, L., Calegari, D., Cali, S., Calvi, M., Gomez, M. Calvo, Campana, P., Perez, D. H. Campora, Quezada, A. F. Campoverde, Canfer, S., Capelli, S., Capriotti, L., Carassiti, V., Carbone, A., Cardinale, R., Cardini, A., Carletti, M., Carniti, P., Carroll, J., Carus, L., Vidal, A. Casais, Caspary, R., Casse, G., Cattaneo, M., Cavallero, G., Cavallini, V., Ceelie, L., Celani, S., Cerasoli, J., Cervenkov, D., Cesare, S., Chadaj, B., Chadwick, A. J., Chahrour, I., Chanal, H., Chapman, M. G., Charles, M., Charpentier, Ph., Chaumat, V. J., Barajas, C. A. Chavez, Chefdeville, M., Chen, C., Chen, S., Chernov, A., Chernov, E., Chernyshenko, S., Chiozzi, S., Chobanova, V., Cholak, S., Chrzaszcz, M., Chubykin, A., Chulikov, V., Ciambrone, P., Cicala, M. F., Vidal, X. Cid, Ciezarek, G., Cifra, P., Citterio, M., Ciullo, G., Clark, K., Clarke, P. E. L., Clemencic, M., Cliff, H. V., Closier, J., Cobbledick, J. L., Coco, V., Coelli, S., Cogan, J., Cogneras, E., Cojocariu, L., Collins, P., Colombo, T., Congedo, L., Conti, N., Contu, A., Cooke, N., Corredoira, I., Corti, G., Ramusino, A. Cotta, Couturier, B., Cowan, G. A., Craik, D. C., Torres, M. Cruz, Currie, R., Da Silva, C. L., Dadabaev, S., Dai, L., Dai, X., Dall'Occo, E., Dalseno, J., D'Ambrosio, C., Damen, A., Daniel, J., Danilina, A., d'Argent, P., Daudon, F., Davies, J. E., Davis, A., Davis, J., Francisco, O. De Aguiar, De Benedetti, F., de Boer, J., De Bruyn, K., De Capua, S., De Cian, M., Da Graca, U. De Freitas Carneiro, De Lucia, E., De Miranda, J. M., de Oliveira, R., De Paula, L., De Roo, K., De Serio, M., De Simone, D., De Simone, P., De Vellis, F., de Vries, J. A., De Wit, E., Dean, C. T., Debernardis, F., Decamp, D., Deckenhoff, M., Dedu, V., Del Buono, L., Delaney, B., Dembinski, H. -P., Denis, C., Denysenko, V., Deschamps, O., Dettori, F., Dey, B., Di Bari, D., Di Nezza, P., Diachkov, I., Didenko, S., Maronas, L. Dieste, Dijkstra, H., Ding, S., Dobishuk, V., Doets, M., Doherty, F., Dolmatov, A., Domke, M., Dong, C., Donohoe, A. M., Dordei, F., Dorosz, P., Reis, A. C. dos, Douglas, L., Downes, A. G., Duarte, O., Duda, P., Dudek, M. W., Dufour, L., Duk, V., Dumps, R., Durante, P., Duras, M. M., Durham, J. M., Dutta, D., Duval, P. Y., Dziewiecki, M., Dziurda, A., Dzyuba, A., Easo, S., Egede, U., Egorychev, V., Orro, C. Eirea, Eisenhardt, S., Ejopu, E., Ekelhof, R., Ek-In, S., Eklund, L., Elashri, M. E, Ellbracht, J., Elvin, A., Ely, S., Ene, A., Epple, E., Escher, S., Eschle, J., Esen, S., Evans, T., Fabiano, F., Falcao, L. N., Fan, Y., Fang, B., Fantini, L., Faria, M., Farry, S., Fazzini, D., Felkowski, L. F, Feo, M., Declara, P. Fernandez, Gomez, M. Fernandez, Fernez, A. D., Ferrari, F., Ferreira, R., Lopes, L. Ferreira, Rodrigues, F. Ferreira, Sole, S. Ferreres, Ferrillo, M., Ferro-Luzzi, M., Filippov, S., Fini, R. A., Fiorini, M., Firlej, M., Fischer, K. M., Fitzgerald, D. S., Fitzpatrick, C., Fiutowski, T., Fleuret, F., Flores, L., Fontana, M., Fontanelli, F., Forty, R., Foulds-Holt, D., Fournier, C., Lima, V. Franco, Sevilla, M. Franco, Frank, M., Franzoso, E., Frau, G., Freestone, J., Frei, C., Frei, R., Frelier, J., Friday, D. A., Frontini, L. F, Fu, J., Fuehring, Q., Fulghesu, T., Fuzipeg, C., Gabriel, E., Galati, G., Galati, M. D., Galka, M., Torreira, A. Gallas, Galli, D., Gallorini, S., Gambetta, S., Gan, Y., Gandelman, M., Gandini, P., Gao, R., Gao, Y., Garau, M., Martin, L. M. Garcia, Moreno, P. Garcia, Pardiñas, J. García, Plana, B. Garcia, Rosales, F. A. Garcia, Garrido, L., Garroum, N., Garsed, P. J., Gascon, D., Gaspar, C., Gasq, C., Gatta, M., Gavardi, L., Gebolis, P. M., Geertsema, R. E., Gerick, D., Gerken, L. L., Germann, D., Gersabeck, E., Gersabeck, M., Gershon, T., Getz, S. A., Giambastiani, L., Gibson, V., Giemza, H. K., Gilman, A. L., Giovannetti, M., Gioventù, A., Girard, O. G., Gironell, P. Gironella, Giugliano, C., Giza, M. A., Gizdov, K., Gkougkousis, E. L., Gligorov, V. V., Göbel, C., Golinka-Bezshyyko, L., Golobardes, E., Golubkov, D., Golutvin, A., Gomes, A., Fernandez, S. Gomez, Abrantes, F. Goncalves, Goncerz, M., Gong, G., Gorelov, I. V., Gotti, C., Grabowski, J. P., Grammatico, T., Cardoso, L. A. Granado, Grant, F., Graugés, E., Graverini, E., Graziani, G., Grecu, A. T., Greeven, L. M., Greim, R., Grieser, N. A., Grillo, L., Gromov, S., Gromov, V., Grub, N., Cazon, B. R. Gruberg, Grynyov, B., Gu, C., Guarise, M., Guerin, S., Guittiere, M., Günther, P. A., Gushchin, E., Guth, A., Guz, Y., Gys, T., Hachon, F., Hadavizadeh, T., Hadjivasiliou, C., Haefeli, G., Haen, C., Haimberger, J., Haines, S. C., Halewood-leagas, T., Halvorsen, M. M., Hamilton, P. M., Hammerich, J., Hamrat, S., Han, Q., Han, X., Hansen, E. B., Hansmann-Menzemer, S., Hao, L., Harnew, N., Harrison, T., Hasse, C., Hatch, M., He, J., Heijhoff, K., Hemmer, F. H, Henderson, C., Henderson, R. D. L., Hennequin, A. M., Hennessy, K., Henry, L., Herd, J., Herold, T., Heuel, J., Hicheur, A., Hill, D., Hilton, M., Hoft, G. T., Hollitt, S. E., Hopchev, P. H., Hornberger, O., Horswill, J., Hou, R., Hou, Y., Hu, J., Hu, W., Hu, X., Huang, W., Huang, X., Hulsbergen, W., Hummel, S., Hunter, R. J., Hushchyn, M., Hutanu, O. E., Hutchcroft, D., Hynds, D., Ibis, P., Idzik, M., Ilin, D., Ilten, P., Inglessi, A., Iniukhin, A., Insa, C., Ishteev, A., Ivshin, K., Jacobsson, R., Jage, H., Elles, S. J. Jaimes, Jakobsen, S., Jamet, O., Jans, E., Jashal, B. K., Jaspers, M., Jawahery, A., Jevaud, M., Jevtic, V., Jiang, E., Jiang, X., Jiang, Y., John, D., John, M., Johnson, D., Jones, C. R., Jones, T. P., Jost, B., Jurik, N., Juszczak, I., Kandybei, S., Kang, Y., Karacson, M., Kariuki, J. M., Karpenkov, D., Karpinski, W., Karpov, M., Kaufmann, K., Kautz, J. W., Kayzel, F., Keizer, F., Keller, D. M., Kenzie, M., Ketel, T., Khanji, B., Kharisova, A., Kholodenko, S., Khreich, G., Kirn, T., Kirsebom, V. S., Kitouni, O., Klaver, S., Kleijne, N., Klimaszewski, K., Kmiec, M. R., Kok, H., Koliiev, S., Kolk, L., Kondybayeva, A., Konoplyannikov, A., Kopciewicz, P., Kopecna, R., Koppenburg, P., Korolev, M., Kos, J., Kostiuk, I., Kot, O., Kotriakhova, S., Kozachuk, A., Kozlov, V. S., Kraan, M., Kravchenko, P., Kravchuk, L., Krawczyk, R. D., Kreps, M., Kretzschmar, S., Krokovny, P., Krupa, W., Krzemien, W., Kubat, J., Kubis, S., Kucewicz, W., Kucharczyk, M., Kudryavtsev, V., Kuhlman, A., Kuilman, W. C., Kulikova, E. K, Kuonen, A. K., Kupfer, N., Kupsc, A., Kvaratskheliya, T., Lacarrere, D., Lafferty, G., Lai, A., Lampis, A., Lancierini, D., Gomez, C. Landesa, Lane, J. J., Lane, R., Langenbruch, C., Langer, J., Langstaff, M., Lantwin, O., Latham, T., Lazzari, F., Lazzaroni, M., Dortz, O. Le, Gac, R. Le, Lee, S. H., Lefèvre, R., Leflat, A., Legotin, S., Lemaitre, F., Lenisa, P., Leroy, O., Lesiak, T., Leverington, B., Li, A., Li, H., Li, K., Li, P., Li, P. -R., Li, S., Li, T., Li, Y., Li, Z., Liang, X., Lieunard, B., Lin, C., Lin, T., Lindner, R., Lisovskyi, V., Litvinov, R., Liu, G., Liu, H., Liu, Q., Liu, S., Salvia, A. Lobo, Loi, A., Lollini, R., Castro, J. Lomba, Longstaff, I., Lopes, J. H., Huertas, A. Lopez, Soliño, S. López, Louis, D., Lovell, G. H., Loveridge, P., Lowe, A. D., Lu, Y., Lucarelli, C., Lucchesi, D., Luchuk, S., Martinez, M. Lucio, Lukashenko, V., Lukianov, A., Luo, H., Luo, Y., Lupato, A., Luppi, E., Lupton, O., Lusiani, A., Lutz, L. F., Lynch, K., Lyu, X. -R., Ma, R., Maccolini, S., Machefert, F., Maciuc, F., Mackay, I., Macko, V., Mackowiak, P., Maddrell-Mander, S., Mohan, L. R. Madhan, Maevskiy, A., Magne, M., Maisuzenko, D., Majewski, M. W., Malaguti, R., Malczewski, J. J., Malde, S., Malecki, B., Malinin, A., Malkinski, K., Maltsev, T., Manca, G., Mancinelli, G., Mancuso, C., Escalero, R. Manera, Manuzzi, D., Manzari, C. A., Marangotto, D., Marchand, J. F., Marconi, U., Mariani, S., Benito, C. Marin, Marks, J., Marshall, A. M., Marshall, P. J., Martelli, G., Martellotti, G., Martinazzoli, L., Martinelli, M., Santos, D. Martinez, Vidal, F. Martinez, Masic, B., Massafferri, A., Materok, M., Matev, R., Mathad, A., Mathe, Z., Matiunin, V., Matteuzzi, C., Mattioli, K. R., Mauri, A., Maurice, E., Mauricio, J., de Cos, J. Mazorra, Mazurek, M., McCann, M., Mcconnell, L., McGrath, T. H., McHugh, N. T., McNab, A., McNulty, R., Mead, J. V., Meadows, B., Meier, G., Meier-villardita, L., Melnychuk, D., Meloni, S., Merk, M., Merli, A., Meunier, J. L., Garcia, L. Meyer, Miao, D., Mikhasenko, M., Milanes, D. A., Millard, E., Miller, G., Milovanovic, M., Minard, M. -N., Minotti, A., Minutoli, S., Miralles, T., Mitchell, S. E., Mitreska, B., Mittelstaedt, T., Mitzel, D. S., Mödden, A., Modenese, L., Mogini, A., Mohammed, R. A., Moise, R. D., Mokhnenko, S., Mombächer, T., Monk, M., Monroy, I. A., Monteil, S., Monti, M., Morandin, M., Morello, G., Morello, M. J., Morgenthaler, M. P., Moron, J., Morris, A. B., Morris, A. G., Mountain, R., Mu, H., Muhammad, E., Muheim, F., Mulder, M., Muley, S., Müller, D., Müller, K., Munneke, B., Murphy, C. H., Murray, D., Murta, R., Muzzetto, P., Naik, P., Naik, S. A., Nakada, T., Nandakumar, R., Nanut, T., Nasteva, I., Nazarov, E., Needham, M., Neri, I., Neri, N., Neubert, S., Neufeld, N., Neustroev, P., Newcombe, R., Trung, T. Nguyen, Nicolini, J., Nicotra, D., Niel, E. M., Nieswand, S., Nikitin, N., Nolte, N. S., Normand, C., Fernandez, J. Novoa, Nowak, G. N, Nunez, C., O'Bannon, T., Oblakowska-Mucha, A., Obraztsov, V., O'Dell, J., Oeser, T., Okamura, S., Oldeman, R., Oliva, F., Olive, P., Onderwater, C. J. G., O'Neil, R. H., Orlov, V., Goicochea, J. M. Otalora, Ovsiannikova, T., Owen, P., Oyanguren, A., Ozcelik, O., Padeken, K. O., Pagare, B., Pais, P. R., Pajero, T., Palano, A., Palutan, M., Pan, Y., Panshin, G., Paoletti, E., Paolucci, L., Papanestis, A., Pappagallo, M., Pappalardo, L. L., Pappenheimer, C., Parker, W., Parkes, C., Pasquali, L., Passalacqua, B., Passaleva, G., Pastore, A., Patel, M., Patrignani, C., Pavlenko, D., Pawley, C. J., Pearce, A., Regales, M. D. P. Peco, Pellegrino, A., Peltier, F., Altarelli, M. Pepe, Perazzini, S., Pereima, D., Castro, A. Pereiro, Perret, P., Perro, A., Perry, M., Pessina, G., Petridis, K., Petrolini, A., Petrucci, S., Petruzzo, M., Pham, H., Philippov, A., Piandani, R., Pica, L., Olloqui, E. Picatoste, Piccini, M., Piedigrossi, D., Pietrzyk, B., Pietrzyk, G., Pili, M., Pillet, N., Pilorz, E. M., Pinci, D., Pisani, F., Pizzichemi, M., Placinta, V., Plews, J., Casasus, M. Plo, Polci, F., Lener, M. Poli, Poluektov, A., Polukhina, N., Polyakov, I., Polyakov, V., Polycarpo, E., Pomery, G. J., Ponce, S., Pons, X., Poplawski, K., Popov, D., Poslavskii, S., Prasanth, K., Pratt, D., Promberger, L., Prouve, C., Pugatch, V., Puill, V., Punzi, G., Qi, H. R., Qian, W., Qin, N., Qu, S., Quagliani, R., Raab, N. V., Rachwal, B., Rademacker, J. H., Rajagopalan, R., Rama, M., Ramaherison, J. J., Pernas, M. Ramos, Rangel, M. S., Ratnikov, F., Raven, G., De Miguel, M. Rebollo, Redi, F., Reich, J., Reiss, F., Alepuz, C. Remon, Ren, Z., Resmi, P. K., Rethore, F., Reynet, D., Ribatti, R., Ricci, A. M., Ricciardi, S., Richards, D. S., Richardson, K., Richardson-Slipper, M., Riedinger, J., Rinnert, K., Robbe, P., Robertson, G., Rochet, J., Rodrigues, A. B., Rodrigues, E., Fernandez, E. Rodriguez, Lopez, J. A. Rodriguez, Perez, P. Rodriguez, Rodriguez, E. Rodriguez, Roeland, E., Rolf, D. L., Rollings, A., Roloff, P., Romanovskiy, V., Lamas, M. Romero, Vidal, A. Romero, Rosier, P., Roth, J. D., Rotondo, M., Rovekamp, J., Roy, L., Rudnyckyj, F., Rudolph, M. S., Ruf, T., Fernandez, R. A. Ruiz, Vidal, J. Ruiz, Ryzhikov, A., Ryzka, J., Silva, J. J. Saborido, Sagidova, N., Sahoo, N., Saitta, B., Salomoni, M., Gras, C. Sanchez, Sanders, F., Sanderswood, I., Santacesaria, R., Rios, C. Santamarina, Santimaria, M., Santovetti, E., Saputi, A., Saranin, D., Sarpis, G., Sarpis, M., Sarti, A., Satriano, C., Satta, A., Saur, M., Saussac, A., Savrina, D., Sazak, H., Sborzacchi, F., Smead, L. G. Scantlebury, Scarabotto, A., Schael, S., Scherl, S., Schiller, M., Schimmel, A., Schindler, H., Schipper, J. D., Schmeitz, R., Schmelling, M., Schmidt, B., Schmitt, S., Schneider, O., Schneider, T., Schopper, A., Schubiger, M., Schulte, S., Schune, M. H., Schwemmer, R., Sciascia, B., Sciuccati, A., Sellam, S., Semennikov, A., Soares, M. Senghi, Sergi, A., Serra, N., Sestak, J., Sestini, L., Seuthe, A., Seyfert, P., Shang, Y., Shangase, D. M., Shapkin, M., Shchemerov, I., Shchutska, L., Shears, T., Shekhtman, L., Shen, Z., Sheng, S., Sherman, M. s, Shevchenko, V., Shi, B., Shields, E. B., Shimizu, Y., Shmanin, E., Shorkin, R., Shupperd, J. D., Siddi, B. G., Siebig, S., Sigmund, D., Sigurdsson, S., Coutinho, R. Silva, Simi, G., Simone, S., Singla, M., Skidmore, N., Skuza, R., Skwarnicki, T., Slater, M. W., Slattery, K., Slazyk, I., Smallwood, J. C., Smeaton, J. G., Smith, E., Smith, K., Smith, M., Smith, N. A., Snoch, A., Lavra, L. Soares, Socha, J-L., Sokoloff, M. D., Soler, F. J. P., Solomin, A., Solovev, A., Solovyev, I., Song, R., De Almeida, F. L. Souza, De Paula, B. Souza, Spaan, B., Norella, E. Spadaro, Spedicato, E., Spiridenkov, E., Spradlin, P., Squerzanti, S., Sriskaran, V., Stagni, F., Stahl, M., Stahl, S., Stanislaus, S., Steffens, E., Stein, E. N., Steinkamp, O., Stenyakin, O., Stevens, H., Stone, S., Stramaglia, M. E., Strekalina, D., Su, Y. S, Suljik, F., Sun, J., Sun, L., Sun, Y., Svihra, P., Swallow, P. N., Swientek, K., Swientek, S., Szabelski, A., Szumlak, T., Szymanski, M., Tagliente, G, Tan, Y., Taneja, S., Tat, M. D., Quere, M. Taurigna, Terentev, A., Terront, D. F., Teubert, F., Thomas, E., Thompson, D. J. D., Thomson, K. A., Tilquin, H., Tisserand, V., T'Jampens, S., Tobin, M., Tomassetti, L., Tonani, G., Tong, X., Topp-Joergensen, S., Machado, D. Torres, Tou, D. Y., Trilov, S. M., Trippl, C., Tuci, G., Tuning, N., Ukleja, A., Unverzagt, D. J., Usachov, A., Ustyuzhanin, A., Uwer, U., Vagner, A., Vagnoni, V., Valassi, A., Valat, S., Valenti, G., Canudas, N. Valls, van Beuzekom, M., Van De Kraats, P. W., van der Heijden, B., Van Dijk, M., van Dongen, J., Van Hecke, H., van Herwijnen, E., Van Hulse, C. B., Van Nieuwland, L., van Overbeek, M., Van Stenis, M., van Veghel, M., Vandaele, R., Gomez, R. Vazquez, Regueiro, P. Vazquez, Sierra, C. Vázquez, Vecchi, S., Veldt, L., Velthuis, J. J., Veltri, M., Venkateswaran, A., Verkooijnen, H., Veronesi, M., Vesterinen, M., Barbosa, J. V. Viana, Vieira, D., Diaz, M. Vieites, Viel, K. J., Vilasis-Cardona, X., Figueras, E. Vilella, Villa, A., Vincent, P., Vink, W., Vitkovskiy, A., Volkov, V., Volle, F. C., Bruch, D. vom, Voneki, B., Vorbach, O., Vorobyev, A., Vorobyev, V., Voropaev, N., Vos, K., Vouters, G., Vrahas, C., Walet, W., Walsh, J., Walton, E. J., Wan, G., Wang, C., Wang, G., Wang, J., Wang, M., Wang, R., Wang, X., Wang, Y., Wang, Z., Ward, J. A., Warda, K., Watson, N. K., Websdale, D., Webster, J., Wei, Y., Westhenry, B. D. C., White, D. J., Whitehead, M., Wieczorek, D., Wiederhold, A. R., Wiedner, D., Wilkinson, G., Wilkinson, M. K., Williams, I., Williams, M., Williams, M. R. J., Williams, R., Wilson, F. F., Wimberley, J., Windelband, B., Wislicki, W., Witek, M., Witola, L., Wlochal, M., Wong, C. P., Wormald, M., Wormser, G., Wotton, S. A., Wraight, K., Wu, H., Wu, J., Wyllie, K., Xiang, Z., Xie, Y., Xu, A., Xu, J., Xu, L., Xu, M., Xu, Q., Xu, Z., Yang, D., Yang, S., Yang, X., Yang, Y., Yang, Z., Yeomans, L. E., Yeroshenko, V., Yeung, H., Yin, H., Yu, J., Yuan, X., Zaffaroni, E., Zavertyaev, M., Zdybal, M., Zenaiev, O., Zeng, M., Zhang, C., Zhang, D., Zhang, L., Zhang, S., Zhang, Y., Zhao, Y., Zharkova, A., Zhelezov, A., Zheng, Y., Zhou, T., Zhou, X., Zhou, Y., Zhovkovska, V., Zhu, X., Zhu, Z., Zhukov, V., Zivkovic, V., Zou, Q., Zucchelli, S., Zuliani, D., Zunica, G., and Zvyagintsev, S.

Subjects
High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract

The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software., Comment: All figures and tables, along with any supplementary material and additional information, are available at http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-DP-2022-002.html (LHCb public pages)

Published
2023
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9. Droplet Finite-Size Scaling of the Majority Vote Model on Quenched Scale-Free Networks

Author

Alencar, D. S. M., Alves, T. F. A., Lima, F. W. S., Ferreira, R. S., Alves, G. A., and Macedo-Filho, A.

Subjects
Condensed Matter - Statistical Mechanics
Abstract

We consider the Majority Vote model coupled with scale-free networks. Recent works point to a non-universal behavior of the Majority Vote model, where the critical exponents depend on the connectivity while the network's effective dimension $D_\mathrm{eff}$ is unity for a degree distribution exponent $5/2<\gamma<7/2$. We present a finite-size theory of the Majority Vote Model for uncorrelated networks and present generalized scaling relations with good agreement with Monte-Carlo simulation results. The presented finite-size theory has two main sources of size dependence. The first source is an external field describing a mass media influence on the consensus formation and the second source is the scale-free network cutoff. The model indeed presents non-universal critical behavior where the critical exponents depend on the degree distribution exponent $5/2<\gamma<7/2$. For $\gamma \geq 7/2$, the model is on the same universality class of the Majority Vote model on Erd\"os-Renyi random graphs, while for $\gamma=7/2$, the critical behavior presents additional logarithmic corrections., Comment: arXiv admin note: text overlap with arXiv:1910.06046

Published
2023

12. Epidemic Outbreaks on Quenched Scale-Free Networks

Author

Alencar, D. S. M., Alves, T. F. A., Lima, F. W. S., Alves, G. A., Macedo-Filho, A., and Ferreira, R. S.

Subjects
Condensed Matter - Statistical Mechanics, Physics - Physics and Society
Abstract

We present a finite-size scaling theory of a contact process with permanent immunity on uncorrelated scale-free networks. We model an epidemic outbreak by an analog of the susceptible-infected-removed model where an infected individual attacks only one susceptible in a time unit in a way we can expect a non-vanishing critical threshold at scale-free networks. As we already know, the susceptible-infected-removed model can be mapped in a bond percolation process, allowing us to compare the critical behavior of site and bond universality classes on networks. We used the external field finite-scale theory, where the dependence on the finite size enters the external field defined as the initial number of infected individuals. We can impose the scale of the external field as $N^{-1}$. The system presents an epidemic-endemic phase transition where the critical behavior obeys the mean-field universality class, as we show theoretically and by simulations.

Published
2022

13. Effects of Autohydrolysis on the Phenolic Extraction and Antioxidant Capacity of Camellia sp. Seed Husk Extracts

Author

Ferreira, R. M., Piñeiro-Lago, B., Saraiva, J. A., Cardoso, S. M., Torres, M. D., Domínguez, H., Bezaeva, Natalia S., Series Editor, Gomes Coe, Heloisa Helena, Series Editor, Nawaz, Muhammad Farrakh, Series Editor, Galvão, João Rafael da Costa Sanches, editor, Brito, Paulo, editor, Neves, Filipe dos Santos, editor, Almeida, Henrique de Amorim, editor, Mourato, Sandra de Jesus Martins, editor, and Nobre, Catarina, editor

Published
2024
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16. Unbound states in quantum heterostructures

Author

Ferreira R and Bastard G

Subjects
Virtual bound states, Quantum Dots, Quantum Wells, Decoherence, Auger effect, Photodetectors, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

AbstractWe report in this review on the electronic continuum states of semiconductor Quantum Wells and Quantum Dots and highlight the decisive part played by the virtual bound states in the optical properties of these structures. The two particles continuum states of Quantum Dots control the decoherence of the excited electron – hole states. The part played by Auger scattering in Quantum Dots is also discussed.

Published
2006
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18. Unfocused laser ignition of high-pressure He-H2-O2 combustible mixtures

Author

Ferreira, R. Grosso, Carvalho, B., Rodrigues, J., Rodrigues, R., Smith, A., Marraffa, L., and da Silva, M. Lino

Subjects
Physics - Chemical Physics
Abstract

We report consistent ignition of high-pressure (p > 20-30 bar) hydrogen-oxygen mixtures diluted with helium, using an unfocused Nd:YAG laser. This corresponds to laser irradiances several orders of magnitude below the minimum ignition energies reported in the literature. By placing a mirror inside a cylindrical vessel and filling it up to 100 bar with H2-He or O2-He non-combustible mixtures, we obtain the pressure-dependent absorptivity of the combustible He-H2-O2 mixture. We find no measurable absorption of the laser signal by the medium, for the overall pressure range, to the experimental apparatus sensitivity (about 1% of the laser irradiance). This leads credence to the theory that ignition stems from seed electrons created by autofocusing ionization of dust/impurities in the gas.

Published
2022

19. Phase Diagram of the Contact Process on Barabasi-Albert Networks

Author

Alencar, D. S. M., Alves, T. F. A., Alves, G. A., Ferreira, R. S., Macedo-Filho, A., and Lima, F. W. S.

Subjects
Physics - Physics and Society, Condensed Matter - Statistical Mechanics
Abstract

We show results for the contact process on Barabasi networks. The contact process is a model for an epidemic spreading without permanent immunity that has an absorbing state. For finite lattices, the absorbing state is the true stationary state, which leads to the need for simulation of quasi-stationary states, which we did in two ways: reactivation by inserting spontaneous infected individuals, or by the quasi-stationary method, where we store a list of active states to continue the simulation when the system visits the absorbing state. The system presents an absorbing phase transition where the critical behavior obeys the Mean Field exponents $\beta=1$, $\gamma'=0$, and $\nu=2$. However, the different quasi-stationary states present distinct finite-size logarithmic corrections. We also report the critical thresholds of the model as a linear function of the network connectivity inverse $1/z$, and the extrapolation of the critical threshold function for $z \to \infty$ yields the basic reproduction number $R_0=1$ of the complete graph, as expected. Decreasing the network connectivity leads to the increase of the critical basic reproduction number $R_0$ for this model., Comment: 14 PAGES, 3 FIGURES, ONE TABLE

Published
2022

20. Prevalence, risk factors and evolution of diabetes mellitus after treatment in primary aldosteronism. Results from the SPAIN-ALDO registry

Author

Araujo-Castro, M., Paja Fano, M., Pla Peris, B., González Boillos, M., Pascual-Corrales, E., García Cano, A. M., Parra Ramírez, P., Martín Rojas-Marcos, P., Ruiz-Sanchez, J. G., Vicente Delgado, A., Gómez Hoyos, E., Ferreira, R., García Sanz, I., Recasens Sala, M., Barahona San Millan, R., Picón César, M. J., Díaz Guardiola, P., Perdomo, C. M., Manjón Miguélez, L., García Centeno, R., Percovich, J. C., Rebollo Román, Á., Gracia Gimeno, P., Robles Lázaro, C., Morales-Ruiz, M., Calatayud Gutiérrez, M., Furio Collao, S. A., Meneses, D., Sampedro Nuñez, M. A., Escudero Quesada, V., Mena Ribas, E., Sanmartín Sánchez, A., Gonzalvo Diaz, C., Lamas, C., Guerrero-Vázquez, R., del Castillo Tous, M., Serrano Gotarredona, J., Michalopoulou Alevras, T., Moya Mateo, E. M., and Hanzu, F. A.

Published
2023
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21. Room temperature two terminal tunnel magnetoresistance in lateral graphene transistor

Author

de Araujo, C. I. L., Teixeira, H. A., Toro, O. O., Liao, C., Borme, J., Benetti, L. C., Schafer, D., Brandt, I. S., Ferreira, R., Alpuim, P., Freitas, P. P., and Pasa, A. A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Applied Physics
Abstract

We investigate the behavior of both pure spin and spin-polarized currents measured with four probe non-local and two probe local configurations up to room temperature and under external gate voltage in a lateral graphene transistor, produced using a standard large-scale microfabrication process. The high spin diffusion length of pristine graphene in the channel, measured both directly and by the Hanle effect, and the tuning of relation between electrode resistance area present in the device architecture, allowed us to observe local tunnel magnetoresistance at room temperature, a new finding for this type of device. Results also indicate that while pure spin currents are less sensitive to temperature variations, spin-polarized current switching by external voltage is more efficient, due to a combination of the Rashba effect and change in carrier mobility by Fermi level shift

Published
2021
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22. Modified Epidemic Diffusive Process on the Apollonian Network

Author

Alencar, D. S. M., Macedo-Filho, A., Alves, T. F. A., Alves, G. A., Ferreira, R. S., and Lima, F. W. S.

Subjects
Condensed Matter - Statistical Mechanics, Physics - Physics and Society
Abstract

We present an analysis of an epidemic spreading process on the Apollonian network that can describe an epidemic spreading in a non-sedentary population. The modified diffusive epidemic process was employed in this analysis in a computational context by means of the Monte Carlo method. Our model has been useful for modeling systems closer to reality consisting of two classes of individuals: susceptible (A) and infected (B). The individuals can diffuse in a network according to constant diffusion rates $D_{A}$ and $D_{B}$, for the classes A and B, respectively, and obeying three diffusive regimes, i.e., $D_{A}D_{B}$. Into the same site $i$, the reaction occurs according to the dynamical rule based on Gillespie's algorithm. Finite-size scaling analysis has shown that our model exhibit continuous phase transition to an absorbing state with a set of critical exponents given by $\beta/\nu=0.66(1)$, $1/\nu=0.46(2)$, and $\gamma/\nu=-0.24(2)$ common to every investigated regime. In summary, the continuous phase transition, characterized by this set of critical exponents, does not have the same exponents of the Mean-Field universality class in both regular lattices and complex networks., Comment: 17 pages, 5 figures. arXiv admin note: text overlap with arXiv:2004.08002

Published
2021

23. EuCAPT White Paper: Opportunities and Challenges for Theoretical Astroparticle Physics in the Next Decade

Author

Batista, R. Alves, Amin, M. A., Barenboim, G., Bartolo, N., Baumann, D., Bauswein, A., Bellini, E., Benisty, D., Bertone, G., Blasi, P., Böhmer, C. G., Bošnjak, Ž., Bringmann, T., Burrage, C., Bustamante, M., Bustillo, J. Calderón, Byrnes, C. T., Calore, F., Catena, R., Cerdeño, D. G., Cerri, S. S., Chianese, M., Clough, K., Cole, A., Coloma, P., Coogan, A., Covi, L., Cutting, D., Davis, A. C., de Rham, C., di Matteo, A., Domènech, G., Drewes, M., Dietrich, T., Edwards, T. D. P., Esteban, I., Erdem, R., Evoli, C., Fasiello, M., Feeney, S. M., Ferreira, R. Z., Fialkov, A., Fornengo, N., Gabici, S., Galatyuk, T., Gaggero, D., Grasso, D., Guépin, C., Harz, J., Herrero-Valea, M., Hinderer, T., Hogg, N. B., Hooper, D. C., Iocco, F., Isern, J., Karchev, K., Kavanagh, B. J., Korsmeier, M., Kotera, K., Koyama, K., Krishnan, B., Lesgourgues, J., Said, J. Levi, Lombriser, L., Lorenz, C. S., Manconi, S., Mapelli, M., Marcowith, A., Markoff, S. B., Marsh, D. J. E., Martinelli, M., Martins, C. J. A. P., Matthews, J. H., Meli, A., Mena, O., Mifsud, J., Bertolami, M. M. Miller, Millington, P., Moesta, P., Nippel, K., Niro, V., O'Connor, E., Oikonomou, F., Paganini, C. F., Pagliaroli, G., Pani, P., Pfrommer, C., Pascoli, S., Pinol, L., Pizzuti, L., Porto, R. A., Pound, A., Quevedo, F., Raffelt, G. G., Raccanelli, A., Ramirez-Ruiz, E., Raveri, M., Renaux-Petel, S., Ricciardone, A., Khalifeh, A. Rida, Riotto, A., Roiban, R., Rubio, J., Sahlén, M., Sabti, N., Sagunski, L., Šarčević, N., Schmitz, K., Schwaller, P., Schwetz, T., Sedrakian, A., Sellentin, E., Serenelli, A., Serpico, P. D., Sfakianakis, E. I., Shalgar, S., Silvestri, A., Tamborra, I., Tanidis, K., Teresi, D., Tokareva, A. A., Tolos, L., Trojanowski, S., Trotta, R., Uhlemann, C., Urban, F. R., Vernizzi, F., van Vliet, A., Villante, F. L., Vincent, A., Vink, J., Vitagliano, E., Weniger, C., Wickenbrock, A., Winter, W., Zell, S., and Zeng, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Astroparticle physics is undergoing a profound transformation, due to a series of extraordinary new results, such as the discovery of high-energy cosmic neutrinos with IceCube, the direct detection of gravitational waves with LIGO and Virgo, and many others. This white paper is the result of a collaborative effort that involved hundreds of theoretical astroparticle physicists and cosmologists, under the coordination of the European Consortium for Astroparticle Theory (EuCAPT). Addressed to the whole astroparticle physics community, it explores upcoming theoretical opportunities and challenges for our field of research, with particular emphasis on the possible synergies among different subfields, and the prospects for solving the most fundamental open questions with multi-messenger observations., Comment: White paper of the European Consortium for Astroparticle Theory (EuCAPT). 135 authors, 400 endorsers, 133 pages, 1382 references

Published
2021

28. The Attitude to Learning Chemistry Instrument (ALChI): Linking Sex, Achievement, and Attitudes

Author

Montes, L. H., Ferreira, R. A., and Rodríguez, C.

Abstract

Attitudes towards learning chemistry have been little studied in secondary school students, especially regarding dimensions related to problem solving, the molecular atomic perspective of chemistry, and real-world connection of chemistry. In the present study, we first aimed to design and assess the psychometric properties of the attitude to learning Chemistry instrument (ALChI). A second aim of the study was to assess sex differences and the relation between achievement and attitudes. Participants were 503 secondary school students, from a central southern region of Chile, who answered a 23-item version of the ALChI. The results of the exploratory factor analysis (EFA) revealed that an 18-item scale was most appropriate grouped into four factors: real world connection (RWC), perceived difficulty in problem-solving (PDPS), confidence in problem solving (CPS), and atomic molecular perspective of chemistry (AMPCh). Confirmatory factor analysis (CFA) confirmed the four-factor structure of the model, with optimal fit indexes. Sex factorial invariance was also obtained for configural, metric, and scalar models, demonstrating that ALChI was invariant for sex. Reliability analysis showed moderate to good indices, which suggests good internal consistency of ALChI. On a descriptive level, the highest mean was for the CPS subscale, which entails that students showed a favourable disposition towards their ability to succeed in solving chemistry problems. A structural equation multiple indicators multiple causes (MIMIC) model was conducted to compare factor latent means for sex and assess the relationship between achievement and attitude latent variables. These analyses revealed that achievement was positively associated with all four latent factors. However, no difference by sex was observed across all four factor means. These findings are partially in line with the results from previous studies in more developed countries where attitudes towards chemistry have been consistently linked to academic performance and male students tend to have more positive attitudes than their female counterpart. Our findings are of relevance for researchers, school teachers, and secondary school students since attitudes towards learning chemistry play an important role in choosing a future career path.

Published
2022
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30. Absence of eigenvalues in the continuous spectrum for Klein-Gordon operators

Author

Ferreira, R., Lima, F. N., and Ribeiro, A. S.

Subjects
Mathematical Physics
Abstract

We construct the one-dimensional analogous of von-Neumann Wigner potential to the relativistic Klein-Gordon operator, in which is defined taking asymptotic mathematical rules in order to obtain existence conditions of eigenvalues embedded in the continuous spectrum. Using our constructed potential, we provide an explicit and analytical example of the Klein-Gordon operator with positive eigenvalues embedded in the so called relativistic "continuum region". Even so in this not standard example, we present the region of the "continuum" where those eigenvalues cannot occur. Besides, the absence of eigenvalues in the continuous spectrum for Klein-Gordon operators is proven to a broad general potential classes, including the minimally coupled electric Coulomb potential. Considering known techniques available in literature for Schrodinger operators, we demonstrate an expression for Klein-Gordon operator written in Schrodinger's form, whereby is determined the mathematical spectrum region of absence of eigenvalues.

Published
2020

31. Ultrasensitive Photoresponse of Graphene Quantum Dot in the Coulomb Blockade Regime to THz Radiation

Author

Riccardi, E., Massabeau, S., Valmorra, F., Messelot, S., Rosticher, M., Tignon, J., Watanabe, K., Taniguchi, T., Delbecq, M., Dhillon, S., Ferreira, R., Balibar, S., Kontos, T., and Mangeney, J.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Graphene quantum dots (GQDs) have recently attracted considerable attention, with appealing properties for terahertz (THz) technology. This includes the demonstration of large thermal bolometric effects in GQDs when illuminated by THz radiation. However, the interaction of THz photons with GQDs in the Coulomb blockade regime - single electron transport regime - remains unexplored. Here, we demonstrate the ultrasensitive photoresponse to THz radiation (from <0.1 to 10 THz) of a hBN-encapsulated GQD in the Coulomb blockade regime at low temperature (170 mK). We show that THz radiation of $\sim$10 pW provides a photocurrent response in the nanoampere range, resulting from a renormalization of the chemical potential of the GQD of $\sim$0.15 meV. We attribute this photoresponse to an interfacial photogating effect. Furthermore, our analysis reveals the absence of thermal effects, opening new directions in the study of coherent quantum effects at THz frequencies in GQDs.

Published
2020
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32. Experimental demonstration of a rapid sweep-tuned spectrum analyzer with temporal resolution based on a spin-torque nano-oscillator

Author

Litvinenko, A., Iurchuk, V., Sethi, P., Louis, S., Tiberkevich, V., Li, J., Jenkins, A., Ferreira, R., Dieny, B., Slavin, A. N., and Ebels, U.

Subjects
Physics - Applied Physics, Electrical Engineering and Systems Science - Signal Processing
Abstract

It is demonstrated experimentally that a spin-torque nano-oscillator (STNO) rapidly sweep-tuned by a bias voltage can be used for time-resolved spectrum analysis of frequency-manipulated microwave signals with complicated multi-tone spectra. The critical reduction in the time of spectrum analysis comes from the naturally small time constants of a nano-sized STNO (1-100 ns). The demonstration is performed on a vortex-state STNO generating in a frequency range around 300 MHz, with frequency down-conversion and matched filtering used for signal processing. It is shown that this STNO-based spectrum analyzer can perform analysis of multi-tone signals, and signals with rapidly changing frequency components with time resolution on a $\mu$s time scale and frequency resolution limited only by the 'bandwidth' theorem. The proposed concept of rapid time-resolved spectrum analysis can be implemented with any type of micro and nano-scale frequency-swept oscillators having low time constants and high oscillation frequency.

Published
2020
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34. COVID-19, Intimate Partner Violence, and Communication Ecologies

Author

Cannon, CEB, Ferreira, R, Buttell, F, and First, J

Subjects
IPV, communication ecology, COVID-19, Psychology, Cognitive Sciences, General Arts, Humanities & Social Sciences, General Arts, Humanities & Social Sciences
Abstract

The purpose of this research is to identify important predictors, related to the ongoing COVID-19 pandemic, of intimate partner violence (IPV) and to provide insight into communication ecologies that can address IPV in disaster contexts. This study uses a cross-sectional design, with purposive snowball sampling, for primary survey data collected over 10 weeks starting the first week in April 2020. A total of 374 adults participated in the study. Logistic binary regression was used to identify key predictors among sociodemographic characteristics, stress related to COVID-19, and perceived stress of group membership for those who reported IPV experiences. A t test was used to statistically differentiate between IPV-reporters and non-IPV reporters based on perceived stress measured by the Perceived Stress Scale. Results indicated that respondents who reported renting, lost income due to COVID-19, and increased nutritional stress were all more likely to belong to the IPV-reporters group. These findings provide insight into additional stressors related to the ongoing pandemic, such as stress due to income loss, nutritional stress, and renting, and their likelihood of increasing IPV victimization. Taken together, these results indicate that additional communication resources are needed for those affected by IPV. Additional findings and implications are further discussed.

Published
2021

35. Spectra of electronic excitations in graphene near Coulomb impurities

Author

Breev, A. I., Ferreira, R., Gitman, D. M., and Voronov, B. L.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Mathematical Physics
Abstract

We study the problem of the electron excitation spectrum in the presence of point-like and regularized Coulomb impurities in gapped graphene. To this end, we use the Dirac model and in the point-like case theory of self-adjoint extensions of symmetric operators. In the point-like case, we construct a family of self-adjoint Hamiltonians describing the excitations for any charge of an impurity. Spectra and (generalized) eigenfunctions for all such Hamiltonians are found. Then, we consider the spectral problem in the case of a regularized Coulomb potential of impurities for a special regularization. We study exact equations for charges of impurities that may generate bound states with energy that coincides with the upper boundary of the negative branch of the continuous spectrum (supercritical charges) and calculate these charges., Comment: 43 pages, 9 figures

Published
2019
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38. Magnetodynamics in orthogonal nanocontact spin-torque nano-oscillators based on magnetic tunnel junctions

Author

Jiang, S., Ahlberg, M., Chung, S., Houshang, A., Ferreira, R., Freitas, P. P., and Åkerman, J.

Subjects
Physics - Applied Physics
Abstract

We demonstrate field and current controlled magnetodynamics in nanocontact spin-torque nano-oscillators (STNOs) based on orthogonal magnetic tunnel junctions (MTJs). We systematically analyze the microwave properties (frequency $f$, linewidth $\Delta f$, power $P$, and frequency tunability $df/dI$) with their physical origins---perpendicular magnetic anisotropy (PMA), damping-like and field-like spin transfer torque (STT), and voltage-controlled magnetic anisotropy (VCMA). These devices present several advantageous characteristics: high emission frequencies ($f> 20$ GHz), high frequency tunability ($df/dI=0.25$~GHz/mA), and zero-field operation ($f\sim 4$ GHz). Furthermore, a detailed investigation of $f(H, I)$ reveals that $df/dI$ is mostly governed by the large VCMA (287~fJ/(V$\cdot$m)), while STT plays a negligible role., Comment: 13 pages, 4 figures

Published
2019
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39. Epidemic Outbreaks on Random Delaunay Triangulations

Author

Alves, T. F. A., Alves, G. A., Macedo-Filho, A., and Ferreira, R. S.

Subjects
Condensed Matter - Statistical Mechanics
Abstract

We study epidemic outbreaks on random Delaunay triangulations by applying Asynchronous SIR (susceptible-infected-removed) model kinetic Monte Carlo dynamics coupled to lattices extracted from the triangulations. In order to investigate the critical behavior of the model, we obtain the cluster size distribution by using Newman-Ziff algorithm, allowing to simulate random inhomogeneous lattices and measure any desired percolation observable. We numerically calculate the order parameter, defined as the wrapping cluster density, the mean cluster size, and Binder cumulant ratio defined for percolation in order to estimate the epidemic threshold. Our findings suggest that the system falls into two-dimensional dynamic percolation universality class and the quenched random disorder is irrelevant, in agreement with results for classical percolation., Comment: 13 pages, 5 figures, 31 cited references

Published
2019

40. Giant optical nonlinearity cancellation in quantum wells

Author

Houver, S., Lebreton, A., Pereira, T. A. S., Xu, G., Colombelli, R., Kundu, I., Li, L. H., Linfield, E. H., Davies, A. G., Mangeney, J., Tignon, J., Ferreira, R., and Dhillon, S. S.

Subjects
Physics - Optics, Condensed Matter - Other Condensed Matter, Quantum Physics
Abstract

Second-order optical nonlinearities can be greatly enhanced by orders of magnitude in resonantly excited nanostructures, theoretically predicted and experimentally investigated in a variety of semiconductor systems. These resonant nonlinearities continually attract attention, particularly in newly discovered materials, but tend not to be as efficient as currently predicted. This limits their exploitation in frequency conversion. Here, we present a clear-cut theoretical and experimental demonstration that the second-order nonlinear susceptibility can vary by orders of magnitude as a result of giant cancellation effects in systems with many confined quantum states. Using terahertz quantum cascade lasers as a model source to investigate interband and intersubband resonant nonlinearities, we show that these giant cancellations are a result of interfering second-order nonlinear contributions of light and heavy hole states. As well as of importance to understand and engineer the resonant optical properties of materials, this work can be employed as a new, extremely sensitive tool to elucidate the bandstructure properties of complex quantum well systems.

Published
2019

47. Using of Fibrin Sealant on Treatment for Tendon Lesion: Study in Vivo

Author

de Freitas Dutra Junior, Enéas, Hidd, S. M. C. M., Amaral, M. M., Maia Filho, A. L. M., Assis, L., Ferreira, R. S., Barraviera, B., Tim, C. R., Magjarevic, Ratko, Series Editor, Ładyżyński, Piotr, Associate Editor, Ibrahim, Fatimah, Associate Editor, Lackovic, Igor, Associate Editor, Rock, Emilio Sacristan, Associate Editor, Bastos-Filho, Teodiano Freire, editor, de Oliveira Caldeira, Eliete Maria, editor, and Frizera-Neto, Anselmo, editor

Published
2022
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48. The Heterologous Fibrin Sealant and Aquatic Exercise Treatment of Tendon Injury in Rats

Author

Hidd, S. M. C. M., Dutra, E. F., Jr, Tim, C. R., Filho, A. L. M. M., Assis, L., Ferreira, R. S., Jr, Barraviera, B., Amaral, M. M., Magjarevic, Ratko, Series Editor, Ładyżyński, Piotr, Associate Editor, Ibrahim, Fatimah, Associate Editor, Lackovic, Igor, Associate Editor, Rock, Emilio Sacristan, Associate Editor, Bastos-Filho, Teodiano Freire, editor, de Oliveira Caldeira, Eliete Maria, editor, and Frizera-Neto, Anselmo, editor

Published
2022
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