Drastic disorded-induced reduction of signal amplification in scale-free networks

Understanding information transmission across a network is a fundamental task for controlling and manipulating both biological and man-made information processing systems. Here, we show how topological resonant-like amplification effects in scale-free networks of signaling devices are drastically reduced when phase disorder in the external signals is considered. This is demonstrated theoretically by means of a star-like network of overdamped bistable systems, and confirmed numerically by simulations of scale-free networks of such systems. The taming effect of the phase disorder is found to be sensitive to the amplification's strength, while the topology-induced amplification mechanism is robust against this kind of quenched disorder in the sense that it does not significantly change the values of the coupling strength where amplification is maximum in its absence.Comment: 5 pages, 4 (double) figure

Designing experiments using digital fabrication in structural dynamics

In engineering, traditional approaches aimed at teaching concepts of dynamics to engineering students include the study of a dense yet sequential theoretical development of proofs and exercises. Structural dynamics are seldom taught experimentally in laboratories since these facilities should be provided with expensive equipment such as wave generators, data-acquisition systems, and heavily wired deployments with sensors. In this paper, the design of an experimental experience in the classroom based upon digital fabrication and modeling tools related to structural dynamics is presented. In particular, all experimental deployments are conceived with low-cost, open-source equipment. The hardware includes Arduino-based open-source electronics whereas the software is based upon object-oriented open-source codes for the development of physical simulations. The set of experiments and the physical simulations are reproducible and scalable in classroom-based environments.Peer ReviewedPostprint (author's final draft

Regulation of human aromatase gene expression in adipose tissue

The conversion of androgens to estrogens is catalyzed by the aromatase enzyme, the product of the CYP19A1 gene, in gonads and peripheral tissues. Estrogens produced in the white adipose tissue (WAT) are postulated to play a central role in the development of postmenopausal breast cancer in women and male obesity-related secondary hypogonadism (MOSH). Obesity-related WAT inflammation is considered one of the main driving forces of excessive aromatization in WAT. Regulation of CYP19A1 gene in WAT involves the activation of the glucocorticoiddependent promoter I.4 and the balanced action of local inducers and repressors. This process is complex, and the mechanism behind the link between adiposity, WAT inflammation and excessive aromatization are not well understood. By using the aromatase reporter (hARO-Luc) mouse model and primary adipose stromal cells (ASCs) and adipose tissue samples, two factors, interleukin 10 (IL-10), an anti-inflammatory cytokine, and CC chemokine ligand 2 (CCL2), a proinflammatory chemokine, were found to modulate aromatase gene expression. While IL-10 acts as a suppressor of CYP19A1 via PI.4, CCL2 stimulates this process in ASCs. This was confirmed in vivo in hARO-Luc mouse model, where obesity-related increase in the expression of aromatase reporter in WAT associated with lower IL-10 and/or higher CCL2 levels. Moreover, subcutaneous fat from obese women expresses significantly higher CCL2 and CYP19A1 mRNA levels. As a further proof-of-concept, we showed that attenuation of WAT inflammation by anti-oxidative plant polyphenols in diet is associated with decrease in aromatase reporter expression in hARO-Luc males. In vitro studies confirmed that polyphenols modulate the expression of CYP19A1 in stromal cells. Overall, these results may bring valuable insights into the mechanisms driving aromatase gene expression in WAT in postmenopausal women and men, as well as new approaches for the prevention of breast cancer.Aromataasientsyymi katalysoi estrogeenituotannon viimeistä vaihetta, jossa androgeenit muuntuvat estrogeeneiksi. Aromataasigeeni (CYP19A1-geeni) ilmentyy erityisesti sukupuolirauhasissa, mutta myös lukuisissa muissa kudoksissa, kuten rasvassa ja aivoissa. Valkoisessa rasvakudoksessa tuotettujen estrogeenien oletetaan vaikuttavan keskeisesti rintasyövän kehitykseen vaihdevuosi-iän ohittaneilla naisilla ja miehillä lihavuuteen liittyvän sekundaarisen hypogonadismin kehittymiseen. Lihavuuteen liittyvää valkoisen rasvakudoksen tulehdusta pidetään merkittävänä paikallista aromatisaatiota lisäävänä tekijänä. Muutokset tulehdusta edistävien ja hillitsevien tekijöiden pitoisuuksissa lisäävät aromataasientsyymin tuotantoa valkoisessa rasvakudoksessa aktivoimalla CYP19A1-geenin ilmentymistä. Ihmisen aromataasigeenin ilmentymistä säätelevät hyvin monet eri tekijät lukuisten kudosspesifisten promoottereiden välityksellä. Rasvakudoksessa aromaasigeenin ilmentymistä säädellään mm. glukokortikoidiriippuvaisen promotterin I.4 kautta. Säätelymekanismi on hyvin monimutkainen ja huonosti tunnettu. Tässä työssä käytettiin naisten rinnan rasvan välikudoksesta eristettyjä mesenkymaalisia soluja, rasvakudosnäytteitä, sekä siirtogeenistä ihmisen aromataasigeenin säätelyalueen raportoijahiirimallia (hARO-Luc). Työssä osoitettiin, että tulehdusta hillitsevä sytokiini interleukiini 10 (IL-10) sekä tulehdusta edistävä CC kemokiini ligandi 2 (CCL2) muokkaavat CYP19A1-geenin ilmentymistä rasvakudoksessa. Rinnan välikudoksen soluissa IL-10 vähensi I.4. promoottorin kautta välittyvää CYP19A1- ilmentymistä kun taas CCL2 lisäsi sitä. Tulos vahvistettiin in vivo hARO-Luc hiirissä osoittaen, että lihavuuteen liittyvä lisääntynyt aromataasiraportoijan ilmentyminen rasvakudoksessa oli yhteydessä kudoksen vähentyneeseen IL-10-pitoisuuteen ja lisääntyneeseen CCL2 pitoisuuteen. Myös lihavien naisten ihonalaisen rasvan näytteissä CYP19A1 ja CCL2 ilmentyivät enemmän kuin vastaavissa normaalipainoisten naisten näytteissä. Lisäksi osoitimme, että rehun antioksidatiiviset kasvipolyfenolit vähensivät valkoisen rasvan matala-asteista tulehdusta ja aromataasiraportoijan ilmentymistä hARO-Luc koirashiirissä, mikä vahvistaa havaintoa rasvakudoksen tulehduksen ja CYP19A1-ilmentymisen välisestä yhteydestä. In vitro tutkimuksemme osoittivat, että kasvien polyphenolit muokkaavat CYP19A1-geenin ilmentymistä rasvan välikudoksen soluissa. Tulokset auttavat ymmärtämään aromataasigeenin ilmentymisen säätelymekanismeja miesten ja vaihdevuosi-iän ohittaneiden naisten rasvakudoksessa ja saattavat tarjota uusia keinoja rintasyövän ehkäisyyn

Dissipative dynamics of a particle in a vibrating periodic potential: Chaos and control

The dissipative chaotic dynamics of a particle subjected to a horizontally vibrating periodic potential is characterized theoretically and confirmed numerically in the case of an external chaos-controlling periodic excitation also acting on the particle. Theoretical predictions concerning the chaotic threshold in parameter space are deduced from the application of Melnikov's method that fully determine the chaos-control scenario. Also, the structure of diverse regularization regions in parameter space is explained theoretically with the aid of an energy analysis. It was found that the phase difference between the two periodic excitations involved plays a crucial role in the chaos-control scenario, with the particular feature that its optimal value depends upon the ratio between the damping coefficient and the excitation frequency. This constitutes a genuine feature of the chaos-control scenario associated with nonsteady potentials which is in contrast to the case of steady potentials. Additionally, we demonstrate the robustness of the chaos-control scenario against the presence of low-intensity Gaussian noise and reshaping of chaos-suppressing excitations

Directed ratchet transport of cold atoms and fluxons driven by biharmonic fields: A unified view

This paper discusses two retrodictions of the theory of ratchet universality which explain previous experimental results concerning directed ratchet transport of cold atoms in dissipative optical lattices in one case and of fluxons in uniform annular Josephson junctions in the other, both driven by biharmonic fields. It has to be emphasized that these retrodictions are in sharp contrast with the current standard explanation of such experimental results, and they offer optimal control of the ratchetlike motion of such entities. New experimental proposals with cold atoms and fluxons are discussed, providing additional tests for novel predictions from ratchet universality. ©2021 American Physical Societ

Impulse-induced optimum signal amplification in scale-free networks

Optimizing information transmission across a network is an essential task for controlling and manipulating generic information-processing systems. Here, we show how topological amplification effects in scale-free networks of signaling devices are optimally enhanced when the impulse transmitted by periodic external signals (time integral over two consecutive zeros) is maximum. This is demonstrated theoretically by means of a star-like network of overdamped bistable systems subjected to generic zero-mean periodic signals and confirmed numerically by simulations of scale-free networks of such systems. Our results show that the enhancer effect of increasing values of the signal''s impulse is due to a correlative increase of the energy transmitted by the periodic signals, while it is found to be resonant-like with respect to the topology-induced amplification mechanism

Dissipative dynamics of a particle in a vibrating periodic potential: Chaos and control

The dissipative chaotic dynamics of a particle subjected to a horizontally vibrating periodic potential is characterized theoretically and confirmed numerically in the case of an external chaos-controlling periodic excitation also acting on the particle. Theoretical predictions concerning the chaotic threshold in parameter space are deduced from the application of Melnikov's method that fully determine the chaos-control scenario. Also, the structure of diverse regularization regions in parameter space is explained theoretically with the aid of an energy analysis. It was found that the phase difference between the two periodic excitations involved plays a crucial role in the chaos-control scenario, with the particular feature that its optimal value depends upon the ratio between the damping coefficient and the excitation frequency. This constitutes a genuine feature of the chaos-control scenario associated with nonsteady potentials which is in contrast to the case of steady potentials. Additionally, we demonstrate the robustness of the chaos-control scenario against the presence of low-intensity Gaussian noise and reshaping of chaos-suppressing excitations.R.C. and J.A.M. acknowledge financial support from the Ministerio de Economía y Competitividad (MINECO, Spain) through Project No. FIS2012-34902 cofinanced by FEDER funds. R.C. acknowledges financial support from the Junta de Extremadura (JEx, Spain) through Project No. GR15146. P.J.M. acknowledge financial support from the Ministerio de Economía y Competitividad (MINECO, Spain) through Project No. FIS2011-25167 cofinanced by FEDER funds.Peer Reviewe