The Applegate mechanism in Post-Common-Envelope Binaries: Investigating the role of rotation

Eclipsing time variations (ETVs) are observed in many close binary systems. In particular, for several post-common-envelope binaries (PCEBs) that consist of a white dwarf and a main sequence star, the O-C diagram suggests that real or apparent orbital period variations are driven by Jupiter-mass planets or as a result of magnetic activity, the so-called Applegate mechanism. The latter explains orbital period variations as a result of changes in the stellar quadrupole moment due to magnetic activity. We explore the feasibility of driving ETVs via the Applegate mechanism for a sample of PCEB systems, including a range of different rotations. Using the MESA code we evolve 12 stars with different masses and rotation rates. We apply a simple dynamo model to their radial profiles to investigate on which scale the predicted activity cycle matches the observed modulation period, and quantify the uncertainty, and further calculate the required energies to drive que Applegate mechanism. We show that the Applegate mechanism is energetically feasible in 5 PCEB systems, and note that these are the systems with the highest rotation rate compared to the critical rotation rate of the main-sequence star. The results suggest that the ratio of physical to critical rotation in the main sequence star is an important indicator for the feasibility of Applegate's mechanism, but exploring larger samples will be necessary to probe this hypothesis.Comment: 9 pages, 5 figures. Accepted for publication in A&

Spontaneous symmetry breaking as a resource for noncritically squeezed light

In the last years we have proposed the use of the mechanism of spontaneous symmetry breaking with the purpose of generating perfect quadrature squeezing. Here we review previous work dealing with spatial (translational and rotational) symmetries, both on optical parametric oscillators and four-wave mixing cavities, as well as present new results. We then extend the phenomenon to the polarization state of the signal field, hence introducing spontaneous polarization symmetry breaking. Finally we propose a Jaynes-Cummings model in which the phenomenon can be investigated at the single-photon-pair level in a non-dissipative case, with the purpose of understanding it from a most fundamental point of view.Comment: Review for the proceedings of SPIE Photonics Europe. 11 pages, 5 figures

Evaluating the capacity of human gut microorganisms to colonize the zebrafish larvae (Danio rerio)

Indexación: Scopus.In this study we evaluated if zebrafish larvae can be colonized by human gut microorganisms. We tested two strategies: (1) through transplantation of a human fecal microbiota and (2) by successively transplanting aerotolerant anaerobic microorganisms, similar to the colonization in the human intestine during early life. We used conventionally raised zebrafish larvae harboring their own aerobic microbiota to improve the colonization of anaerobic microorganisms. The results showed with the fecal transplant, that some members of the human gut microbiota were transferred to larvae. Bacillus, Roseburia, Prevotella, Oscillospira, one unclassified genus of the family Ruminococcaceae and Enterobacteriaceae were detected in 3 days post fertilization (dpf) larvae; however only Bacillus persisted to 7 dpf. Successive inoculation of Lactobacillus, Bifidobacterium and Clostridioides did not improve their colonization, compared to individual inoculation of each bacterial species. Interestingly, the sporulating bacteria Bacillus clausii and Clostridioides difficile were the most persistent microorganisms. Their endospores persisted at least 5 days after inoculating 3 dpf larvae. However, when 5 dpf larvae were inoculated, the proportion of vegetative cells in larvae increased, revealing proliferation of the inoculated bacteria and better colonization of the host. In conclusion, these results suggest that it is feasible to colonize zebrafish larvae with some human bacteria, such as C. difficile and Bacillus and open an interesting area to study interactions between these microorganisms and the host. © 2018 Valenzuela, Caruffo, Herrera, Medina, Coronado, Feijóo, Muñoz, Garrido, Troncoso, Figueroa, Toro, Reyes-Jara, Magne and Navarrete.https://www.frontiersin.org/articles/10.3389/fmicb.2018.01032/ful

Estudio electrocardiografía en estación y de cúbito lateral derecho en crías de alpaca (Vicugna pacos)

The aim of the study was to determine the electrocardiographic parameters in both station and right lateral decubitus positions in baby alpacas. The work was done in 30 alpacas (17 males and 13 females) of 60 days old, from the communities alpaqueras Maranganí, Canchis in Cusco. The electrocardiographic values in station and right lateral decubitus were: heart rate 124.83 and 114.16, P wave duration 0.04 and 0.04 s, P wave amplitude 0.180 and 0.173 mV, duration and PQ 0.101 s 0.102, 0.039 and 0.038 QRS duration s, QRS complex 0.643 and 0.557 mV, duration and QT 0.225 0.2370.040 s, T wave amplitude 0.393 and 0.413 mV. The values of ECG parameters showed no significant differences between the two positions. We conclude that is possible to use any positions for the clinic examen in alpacas.El presente estudio tuvo por objetivo determinar los parámetros electrocardiográficos en las posiciones estación y decúbito lateral derecha en crías de alpacas. El trabajo se hizo en 30 alpacas (17 machos y 13 hembras) menores de 60 días de edad, provenientes de las comunidades alpaqueras de Maranganí, Canchis, en Cusco. Los valores electrocardiográficos en estación y en decúbito lateral derecho fueron: Frecuencia cardiaca 124.83 y 114.16, Duración onda P 0.04 y 0.04 s, amplitud onda P 0.180 y 0.173 mV, duración PQ 0.102 y 0.101 s, duración QRS 0.039 y 0.038 s, complejo QRS 0.643 y 0.557 mV, duración QT 0.225 y 0.2370.040 s, amplitud onda T 0.393 y 0.413 mV, los valores no mostraron diferencias significativas al comparalos entre ambas posiciones. Se concluye que en alpacas se puede usar indiferentemente cualquiera de las dos posiciones electrocardiográficas para fines clínico

UVA-induced loss of quinolone antibacterial activity

Se investiga la actividad antibacteriana de soluciones de las quinolonas ácido nalidíxico, ciprofloxacino y levofloxacino irradiadas mediante luz UVA. La fotólisis de las quinolonas produce una disminución de la actividad antibacteriana en cepas de E.coli y de S.aureus, evidenciándose un aumento de la concentración mínima inhibitoria de un 50% frente a las cepas ensayadas, en relación a las quinolonas no irradiadas. Se postula un mecanismo fotolítico radicalario con la consecuente fotodegradación de la porción γ-piridona-β-carboxílica responsable de la actividad antibacteriana.The antibacterial activity of UVA-irradiated solutions of nalidixic acid, ciprofloxacin and levofloxacin was investigated. Photolysis of quinolones produced a decrease in antibacterial activity in strains of E. coli and S. aureus, becoming manifest through an increase of 50% in the minimum inhibitory concentration of the drug as compared to nonirradiated quinolones. In this study, it is suggested that a radical-mediated photolytic mechanism exists, leading to the photodegradation of the γ-piridone-β-carboxylic group, which is the mediator that is responsible for the drugs antibacterial activity

UVA-induced loss of quinolone antibacterial activity

Se investiga la actividad antibacteriana de soluciones de las quinolonas ácido nalidíxico, ciprofloxacino y levofloxacinoirradiadas mediante luz UVA. La fotólisis de las quinolonas produce una disminución de la actividad antibacterianaen cepas de E.coli y de S.aureus, evidenciándose un aumento de la concentración mínima inhibitoria de un 50%frente a las cepas ensayadas, en relación a las quinolonas no irradiadas. Se postula un mecanismo fotolítico radicalariocon la consecuente fotodegradación de la porción γ-piridona-β-carboxílica responsable de la actividad antibacterianaThe antibacterial activity of UVA-irradiated solutions of nalidixic acid, ciprofloxacin and levofloxacin was investigated.Photolysis of quinolones produced a decrease in antibacterial activity in strains of E. coli and S. aureus, becomingmanifest through an increase of 50% in the minimum inhibitory concentration of the drug as compared to nonirradiatedquinolones. In this study, it is suggested that a radical-mediated photolytic mechanism exists, leading to thephotodegradation of the γ-piridone-β-carboxylic group, which is the mediator that is responsible for the drugs antibacterialactivit

Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions

The generation of continuous-variable multipartite entangled states is important for several protocols of quantum information processing and communication, such as one-way quantum computation or controlled dense coding. In this article we theoretically show that multimode optical parametric oscillators can produce a great variety of such states by an appropriate control of the parametric interaction, what we accomplish by tailoring either the spatio-temporal shape of the pump, or the geometry of the nonlinear medium. Specific examples involving currently available optical parametric oscillators are given, hence showing that our ideas are within reach of present technology.Comment: 14 pages, 5 figure