September 2021 - semfis - Mailing lists@ IFISC

Reminder: Master Thesis, TODAY - Thursday, Sep 30, 2021 at 11:00
by semfis＠ifisc.uib-csic.es 30 Sep '21

30 Sep '21

Master Thesis on Thursday Sep 30, 2021 at 11:00 Place: IFISC Seminar Room Title: A compartmental model for vector transmitted diseases: an application to Xylella fastidiosa Speaker: Rosa Flaquer Galmés, IFISC Abstract: In 2016 the presence of the bacterium Xylella fastidiosa was detected in Majorcan almond trees and was regarded as the causal pathogen agent of the mortality of these trees over the last fifteen years. Xylella fastidiosa, being endemic of the Americas, is an insect-transmitted bacterium which is considered one of the major threats to plants worldwide for its large number of hosts, strains and potential vectors. By 2017 the reported incidence of the bacterium over Majorcan almond trees was 79.5% &plusmn; 2.0, presenting a great danger to one of the historical crops of the Balearic Islands. then, the aim of this project is to develop a first step on the study of this epidemic by means of a deterministic compartmental (mean-field) model. In particular, we present a model for the vector assisted transmission of the pathogen, performing an analytical and computational analysis. The model incorporates the specific biological and epidemiological considerations of the bacterium Xylella fastidiosa and its interactions with insects and hosts in Majorca Island. In our work the vector (insect) population varies with time, mimicking the field observations. One of the conclusions is that, in general, this temporal variation hinders the theoretical characterization of epidemic thresholds. Advisor: Manuel Matias Jury: Jose J. Ramasco; Dami&agrave; Gomila; Manuel Matias Url event:https://ifisc.uib-csic.es/en/events/seminars/a-compartmental-model-for-vector-transmitted-disea/

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Reminder: IFISC Seminar, TODAY - Wednesday, Sep 29, 2021 at 14:30
by semfis＠ifisc.uib-csic.es 29 Sep '21

29 Sep '21

IFISC Seminar on Wednesday Sep 29, 2021 at 14:30 Place: Zoom Seminar Title: Non Markovian effects with emphasis on the voter model with aging Speaker: Raul Toral, IFISC / UIB Abstract: It is well known that the presence of delay terms in a dynamical system can induce oscillations. However, much less is known about the effect that such memory terms have on a stochastic dynamical system. In those systems, the Markovian assumption, namely that the transition rates only depend on the current state of the system and not on its previous history, obviously wrong in many situations, is widely used because of its mathematical simplicity. After reviewing some general results on stochastic birth and death processes, I will consider in detail the case of aging, or reluctance to change state as a function of the time spent in the current state, in the voter model with noise. This is a widely used model in social and economics situations to describe transitions to consensus or synchronized behavior. While the model displays a discontinuous change of behavior from unsynchronized to consensus as a function of a parameter which depends on the tendency to act independen tly on the neighbors, this transition is size-dependent and disappears in the thermodynamic limit. I will show that a genuine -second order- phase transition can appear as a consequence of aging. Zoom:&nbsp;<a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/non-markovian-effects-with-emphasis-on-the-voter-m/

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Reminder: Talk, TODAY - Monday, Sep 27, 2021 at 12:00
by semfis＠ifisc.uib-csic.es 27 Sep '21

27 Sep '21

Talk on Monday Sep 27, 2021 at 12:00 Place: IFISC Seminar Room Title: Unveiling predictive coding mechanisms through computational modeling Speaker: Javier Galván, IFISC Abstract: Since we started to interact with the outside world, we have learned to distinguish whether the movement is coming from our own actions or from the movement of external objects. To distinguish between these experiences, it is necessary to factor out the sensory consequences of our actions from incoming sensory information. The main theoretical framework accounting for this computation is predictive coding which proposes to understand top-down inputs from higher visual areas as predictions of bottom-up sensory inputs. However, the structural rules underlying these functional properties of cortical circuits are poorly understood. For that matter, our research aims at integrating insights into the architecture and function of laminar local cortical microcircuits in the neocortex. Particularly, we unveil some of the predictive coding mechanisms using a computational model for a microcircuit of area V1 in mice built on a huge body of experimental work published by the Allen Institute. Url event:https://ifisc.uib-csic.es/en/events/seminars/unveiling-predictive-coding-mechanisms-through-com/

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Talk on Monday, Sep 27, 2021 at 12:00
by semfis＠ifisc.uib-csic.es 25 Sep '21

25 Sep '21

Talk on Monday Sep 27, 2021 at 12:00 Place: IFISC Seminar Room Title: Unveiling predictive coding mechanisms through computational modeling Speaker: Javier Galván, IFISC Abstract: Since we started to interact with the outside world, we have learned to distinguish whether the movement is coming from our own actions or from the movement of external objects. To distinguish between these experiences, it is necessary to factor out the sensory consequences of our actions from incoming sensory information. The main theoretical framework accounting for this computation is predictive coding which proposes to understand top-down inputs from higher visual areas as predictions of bottom-up sensory inputs. However, the structural rules underlying these functional properties of cortical circuits are poorly understood. For that matter, our research aims at integrating insights into the architecture and function of laminar local cortical microcircuits in the neocortex. Particularly, we unveil some of the predictive coding mechanisms using a computational model for a microcircuit of area V1 in mice built on a huge body of experimental work published by the Allen Institute. Url event:https://ifisc.uib-csic.es/en/events/seminars/unveiling-predictive-coding-mechanisms-through-com/

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IFISC Seminar on Wednesday, Sep 29, 2021 at 14:30
by semfis＠ifisc.uib-csic.es 25 Sep '21

25 Sep '21

IFISC Seminar on Wednesday Sep 29, 2021 at 14:30 Place: Zoom Seminar Title: Non Markovian effects with emphasis on the voter model with aging Speaker: Raul Toral, IFISC / UIB Abstract: It is well known that the presence of delay terms in a dynamical system can induce oscillations. However, much less is known about the effect that such memory terms have on a stochastic dynamical system. In those systems, the Markovian assumption, namely that the transition rates only depend on the current state of the system and not on its previous history, obviously wrong in many situations, is widely used because of its mathematical simplicity. After reviewing some general results on stochastic birth and death processes, I will consider in detail the case of aging, or reluctance to change state as a function of the time spent in the current state, in the voter model with noise. This is a widely used model in social and economics situations to describe transitions to consensus or synchronized behavior. While the model displays a discontinuous change of behavior from unsynchronized to consensus as a function of a parameter which depends on the tendency to act independen tly on the neighbors, this transition is size-dependent and disappears in the thermodynamic limit. I will show that a genuine -second order- phase transition can appear as a consequence of aging. Zoom:&nbsp;<a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/non-markovian-effects-with-emphasis-on-the-voter-m/

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Reminder: Talk, TODAY - Thursday, Sep 23, 2021 at 12:00
by semfis＠ifisc.uib-csic.es 23 Sep '21

23 Sep '21

Talk on Thursday Sep 23, 2021 at 12:00 Place: Zoom Seminar Title: Deep Randomized Neural Networks Speaker: Claudio Gallicchio, University of Pisa, Italy Abstract: Deep Neural Networks (DNNs) are a fundamental tool in the modern development of Machine Learning. Beyond the merits of the training algorithms, a great part of&nbsp;DNNs success is due to the inherent properties of their layered architectures, i.e., to the introduced architectural biases. This talk explores recent classes of DNN models in which&nbsp;the majority of connections are untrained, i.e., randomized or more generally fixed according to some specific heuristic.&nbsp; Limiting the training algorithms to operate on a reduced set of weights implies intriguing features. Among them, the extreme efficiency of the learning processes is undoubtedly a&nbsp;striking advantage with respect to fully trained counterparts. Besides, despite the involved simplifications, randomized neural systems possess remarkable properties both in&nbsp;practice, achieving state-of-the-art results in multiple domains, and theoretically, allowing us to analyze intrinsic properties of neural architectures. This talk will cover the major aspects regarding Deep Randomized Neural Networks, with a particular focus on Deep Reservoir Computers for time-series and graphs. &nbsp; Link Zoom:&nbsp;<a href="https://uibuniversitat.zoom.us/j/83043347066">https://uibuniversitat.zoom.us/j/83043347066</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/deep-randomized-neural-networks/

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Reminder: IFISC Seminar, TODAY - Wednesday, Sep 22, 2021 at 14:30
by semfis＠ifisc.uib-csic.es 22 Sep '21

22 Sep '21

IFISC Seminar on Wednesday Sep 22, 2021 at 14:30 Place: Zoom Seminar Title: Inter-specific interactions in seagrass meadows: a microscopic numerical approach. Speaker: Eva Llabrés, IFISC Abstract: Seagrasses are a key element in the Mediterranean sea, and the drastic demise of their population in the last decades has worrying implications for marine ecosystems. Spatial models for seagrass meadorws provide us with a mathematical framework to study their non-linear dynamics and the emergent collective behaviour. These models are crucial to predict the response of seagrasses to different global warming scenarios, analyze the resilience of existing seagrass patterns and optimize replantation techniques. In this seminar, we present the results of a microscopic numerical model, based on clonal growth rules, in which &nbsp;the interactions among different species have been considered. As a model test case we have considered the&nbsp;seagrass-seaweed interaction between&nbsp;Cymodocea nodosa&nbsp;and&nbsp;Caulerpa prolifera. Our results&nbsp;&nbsp;successfully reproduce field observations of shoot densities in mixed meadows in the Alfacs Bay (Ebro River Delta). Besides, the proposed model allows us to investigate the possible underlying mechanisms that mediate the interaction among plants. Zoom: <a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/inter-specific-interactions-in-seagrass-meadows-a/

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Reminder: Talk, TODAY - Tuesday, Sep 21, 2021 at 14:00
by semfis＠ifisc.uib-csic.es 21 Sep '21

21 Sep '21

Talk on Tuesday Sep 21, 2021 at 14:00 Place: Zoom Seminar Title: Scattering of topological kink-antikink states in bilayer graphene structures Speaker: Nassima Benchtaber, IFISC Abstract: <div> <div> <div> Kink gate potentials applied to bilayer graphene give rise to topological confined states. Electrons in these states display valley-momentum locking, which makes them attractive for topological valleytronics. We study [1] two topological king-antikink constrictions, namely, a quasi-one-dimensional channel working as a quantun point contact and a detaching loop acting as a quantum dot. For the former, we find an anomalous quantized conductance; for the latter, we find that the conductance curves gives information on the system energy spectrum. Interestingly, in the presence of tiny magnetic field the device can work as a valley filter. [1] N. Benchtaber, D. Sanchez and L. Serra, arXiv:2103.13323 (2021). Zoom: <a href="https://uibuniversitat.zoom.us/j/84778591747" style="box-sizing: border-box; background: rgb(255, 255, 255); color: rgb(62, 141, 239); text-decoration: underline; outline: -webkit-focus-ring-color auto 5px; outline-offset: -2px; font-family: Lato, Helvetica, Arial; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; overflow-wrap: break-word;" target="_blank">https://uibuniversitat.zoom.us/j/84778591747</a> </div> </div> </div> Url event:https://ifisc.uib-csic.es/en/events/seminars/scattering-of-topological-kink-antikink-states-in/

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Talk on Tuesday, Sep 21, 2021 at 14:00
by semfis＠ifisc.uib-csic.es 17 Sep '21

17 Sep '21

Talk on Tuesday Sep 21, 2021 at 14:00 Place: Zoom Seminar Title: Scattering of topological kink-antikink states in bilayer graphene structures Speaker: Nassima Benchtaber, IFISC Abstract: <div> <div> <div> Kink gate potentials applied to bilayer graphene give rise to topological confined states. Electrons in these states display valley-momentum locking, which makes them attractive for topological valleytronics. We study [1] two topological king-antikink constrictions, namely, a quasi-one-dimensional channel working as a quantun point contact and a detaching loop acting as a quantum dot. For the former, we find an anomalous quantized conductance; for the latter, we find that the conductance curves gives information on the system energy spectrum. Interestingly, in the presence of tiny magnetic field the device can work as a valley filter. [1] N. Benchtaber, D. Sanchez and L. Serra, arXiv:2103.13323 (2021). Zoom: <a href="https://uibuniversitat.zoom.us/j/84778591747" style="box-sizing: border-box; background: rgb(255, 255, 255); color: rgb(62, 141, 239); text-decoration: underline; outline: -webkit-focus-ring-color auto 5px; outline-offset: -2px; font-family: Lato, Helvetica, Arial; font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; overflow-wrap: break-word;" target="_blank">https://uibuniversitat.zoom.us/j/84778591747</a> </div> </div> </div> Url event:https://ifisc.uib-csic.es/en/events/seminars/scattering-of-topological-kink-antikink-states-in/

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IFISC Seminar on Wednesday, Sep 22, 2021 at 14:30
by semfis＠ifisc.uib-csic.es 17 Sep '21

17 Sep '21

IFISC Seminar on Wednesday Sep 22, 2021 at 14:30 Place: Zoom Seminar Title: Inter-specific interactions in seagrass meadows: a microscopic numerical approach. Speaker: Eva Llabrés, IFISC Abstract: Seagrasses are a key element in the Mediterranean sea, and the drastic demise of their population in the last decades has worrying implications for marine ecosystems. Spatial models for seagrass meadorws provide us with a mathematical framework to study their non-linear dynamics and the emergent collective behaviour. These models are crucial to predict the response of seagrasses to different global warming scenarios, analyze the resilience of existing seagrass patterns and optimize replantation techniques. In this seminar, we present the results of a microscopic numerical model, based on clonal growth rules, in which &nbsp;the interactions among different species have been considered. As a model test case we have considered the&nbsp;seagrass-seaweed interaction between&nbsp;Cymodocea nodosa&nbsp;and&nbsp;Caulerpa prolifera. Our results&nbsp;&nbsp;successfully reproduce field observations of shoot densities in mixed meadows in the Alfacs Bay (Ebro River Delta). Besides, the proposed model allows us to investigate the possible underlying mechanisms that mediate the interaction among plants. Zoom: <a href="https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09">https://us02web.zoom.us/j/83829318876?pwd=Z2pqbUtIMEV3NUQvU0hpakp0NGtsUT09</a> Url event:https://ifisc.uib-csic.es/en/events/seminars/inter-specific-interactions-in-seagrass-meadows-a/

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