Crafting zero-bias one-way transport of charge and spin

We explore the electronic structure and transport properties of a metal on top of a (weakly coupled) two-dimensional topological insulator. Unlike the widely studied junctions between topological non-trivial materials, the systems studied here allow for a unique bandstructure and transport steering. First, states on the topological insulator layer may coexist with the gapless bulk and, second, the edge states on one edge can be selectively switched-off, thereby leading to nearly perfect directional transport of charge and spin even in the zero bias limit. We illustrate these phenomena for Bernal stacked bilayer graphene with Haldane or intrinsic spin-orbit terms and a perpendicular bias voltage. This opens a path for realizing directed transport in materials such as van der Waals heterostructures, monolayer and ultrathin topological insulators.Comment: 7 pages, 7 figure

Floquet topological transitions in a driven one-dimensional topological insulator

The Su-Schrieffer-Heeger model of polyacetylene is a paradigmatic Hamiltonian exhibiting non-trivial edge states. By using Floquet theory we study how the spectrum of this one-dimensional topological insulator is affected by a time-dependent potential. In particular, we evidence the competition among different photon-assisted processes and the native topology of the unperturbed Hamiltonian to settle the resulting topology at different driving frequencies. While some regions of the quasienergy spectrum develop new gaps hosting Floquet edge states, the native gap can be dramatically reduced and the original edge states may be destroyed or replaced by new Floquet edge states. Our study is complemented by an analysis of Zak phase applied to the Floquet bands. Besides serving as a simple example for understanding the physics of driven topological phases, our results could find a promising test-ground in cold matter experiments

Insect (Arthropoda: Insecta) Composition in the Diet of Ornate Box Turtles (Terrapene ornata ornata) in Two Western Illinois Sand Prairies, with a New State Record for Cyclocephala (Coleoptera: Scarabaeidae)

A study of fecal samples collected over a two-year period from juvenile ornate box turtles (Terrapene ornata ornata Agassiz) revealed diets consisting of six orders of insects representing 19 families. Turtles were reared in captivity from eggs harvested from local, wild populations, and released at two remnant prairies. Identifiable insect fragments were found in 94% of samples in 2013 (n=33) and 96% in 2014 (n=25). Frequency of occurrence of insects in turtle feces is similar to results reported in previous studies of midwestern Terrapene species. A comparison of insect composition presented no significant difference between release sites. There is no significant difference in consumed insect species between turtles released into or outside of a fenced enclosure at the same site. Specimens of Cyclocephala longula LeConte collected during this study represent a new state record for Illinois

Delays induce novel stochastic effects in negative feedback gene circuits

AbstractStochastic models of reaction networks are widely used to depict gene expression dynamics. However, stochastic does not necessarily imply accurate, as subtle assumptions can yield erroneous results, masking key discrete effects. For instance, transcription and translation are not instantaneous processes—explicit delays separate their initiation from the appearance of their functional products. However, delays are often ignored in stochastic, single-gene expression models. By consequence, effects such as delay-induced stochastic oscillations at the single-cell level have remained relatively unexplored. Here, we present a systematic study of periodicity and multimodality in a simple gene circuit with negative feedback, analyzing the influence of negative feedback strength and transcriptional/translational delays on expression dynamics. We demonstrate that an oscillatory regime emerges through a Hopf bifurcation in both deterministic and stochastic frameworks. Of importance, a shift in the stochastic Hopf bifurcation evidences inaccuracies of the deterministic bifurcation analysis. Furthermore, noise fluctuations within stochastic oscillations decrease alongside increasing values of transcriptional delays and within a specific range of negative feedback strengths, whereas a strong feedback is associated with oscillations triggered by bursts. Finally, we demonstrate that explicitly accounting for delays increases the number of accessible states in the multimodal regime, and also introduces features typical of excitable systems

The long and viscous road: uncovering nuclear diffusion barriers in closed mitosis.

This is the final version of the article. Available from Public Library of Science via the DOI in this record.Diffusion barriers are effective means for constraining protein lateral exchange in cellular membranes. In Saccharomyces cerevisiae, they have been shown to sustain parental identity through asymmetric segregation of ageing factors during closed mitosis. Even though barriers have been extensively studied in the plasma membrane, their identity and organization within the nucleus remains poorly understood. Based on different lines of experimental evidence, we present a model of the composition and structural organization of a nuclear diffusion barrier during anaphase. By means of spatial stochastic simulations, we propose how specialised lipid domains, protein rings, and morphological changes of the nucleus may coordinate to restrict protein exchange between mother and daughter nuclear lobes. We explore distinct, plausible configurations of these diffusion barriers and offer testable predictions regarding their protein exclusion properties and the diffusion regimes they generate. Our model predicts that, while a specialised lipid domain and an immobile protein ring at the bud neck can compartmentalize the nucleus during early anaphase; a specialised lipid domain spanning the elongated bridge between lobes would be entirely sufficient during late anaphase. Our work shows how complex nuclear diffusion barriers in closed mitosis may arise from simple nanoscale biophysical interactions.OIST funding

Near-infrared spectroscopy study of tourniquet-induced forearm ischaemia in patients with coronary artery disease

Near-Infrared Spectroscopy (NIR) can be employed to monitor local changes in haemodynamics and oxygenation of human tissues. A preliminary study has been performed in order to evaluate the NIRS transmittance response to induced forearm ischaemia in patients with coronary artery disease (CAD). The population consists in 40 patients with cardiovascular risk factors and angiographically documented CAD, compared to a group of 13 normal subjects. By inflating and subsequently deflating a cuff placed around the patient arm, an ischaemia has been induced and released, and the patients have been observed until recovery of the basal conditions. A custom LAIRS spectrometer (IRIS) has been used to collect the backscattered light intensities from the patient forearm throughout the ischaemic and the recovery phase. The time dependence of the near-infrared transmittance on the control group is consistent with the available literature. On the contrary, the magnitude and dynamics of the NIRS signal on the CAD patients show deviations from the documented normal behavior, which can be tentatively attributed to abnormal vessel stiffness. These preliminary results, while validating the performance of the IRIS spectrometer, are strongly conducive towards the applicability of the NIRS technique to ischaemia analysis and to endothelial dysfunction characterization in CAD patients with cardiovascular risk factors.Publisher PD

Exploring drivers of consumer well-being in music festivals: a relationship marketing approach

In the recent decades, the music festivals industry has developed very fast as well as contributed for the growth of wealth in the tourism sector. However, the research up-to-date about festivals is at an early stage, as there are plenty concepts and themes that have not been explored yet. Therefore, this study is motivated to explore what is behind the music festivals’ phenomenon. This dissertation considers the context of music festivals in Portugal due to its increasing levels of tourism growth, and investigates the existing relationships between common concepts within the field of Relationship Marketing, such as consumer’s experience, emotions and level of satisfaction, and yet their level engagement and their sense of well-being. In order to establish a connection between all these constructs, the S-O-R framework developed by Mehrabian and Russell (1974), regarded as one of the most influential in environmental psychology, was adapted to this study to carry this investigation. The results of the study revealed that all the constructs explored in the study show a positive relationship that enables to better comprehend the music festival experience felt by visitors, but it should be noted that not all the dimensions of each construct can be considered as relevant to our theoretical model. The overall findings in the Conclusion Chapter presented some interesting information, particularly, the relationship between consumers’ engagement and well-being, because it provides innovative and revealing facts that have not been explored previously in the music festivals literature. The managerial implications concerned to this study are discussed at the end.Nas últimas décadas, a indústria dos festivais de música tem vindo a desenvolver-se rapidamente, como ainda tem contribuído para o crescimento da riqueza que é gerada através do sector do turismo. No entanto, a pesquisa que é recolhida até à data acerca de festivais encontra-se ainda numa fase inicial, uma vez que existem vários conceitos e temas que não foram ainda investigados. Desta forma, este estudo é motivado a explorar o que está por detrás do fenómeno dos festivais de música. Esta dissertação considera o contexto dos festivais de música em Portugal, devido aos altos níveis de crescimento do seu turismo, e investiga as relações entre alguns conceitos que são comuns na área do Marketing Relacional, como por exemplo, a experiência dos consumidores, as suas emoções e satisfação, e ainda os seus níveis de compromisso, e as suas sensações de bem-estar. De maneira a estabelecer uma conexão entre todos estes conceitos, o framework S-O-R desenvolvido por Mehrabian e Russell (1974), reconhecido como um dos mais influentes na área de psicologia ambiental, foi adaptado a este estudo para que fosse conduzida esta investigação. Os resultados deste estudo revelaram que todos os constructos explorados neste estudo demonstram uma relação positiva que permite compreender melhor a experiência dos festivais de música sentida pelos visitantes, mas deve também ser referido que nem todas as dimensões de cada constructo podem ser consideradas como relevantes para este modelo teórico. Os resultados gerais que se encontram no capítulo das conclusões apresentaram informação relevante, nomeadamente, a relação entre compromisso e bem-estar dos consumidores, por apresentar factos inovadores e reveladores que não foram ainda explorados na literatura dos festivais de música. As implicações que foram reconhecidas neste estudo são discutidas no final do mesmo

Características del emplazamiento, Petrología y Geoquímica de Espessartitas en el Plutón de la Maladeta: estudio preliminar

[Resumen] Los diques de lamprófidos espessartíticos son frecuentes en el plutón circunscrito de La Maladeta (Pirineos Centrales, Huesca-Lérida). Su emplazamiento, se produjo bajo unas condiciones confinadas y con un control estructural, afectando a todos los litotipos plutónicos (Cuarzo-Gabros, Granodioritas, Tonalitas y Sienogranitos) y, también a las etapas filonianas ácidas (Aplita y Pegmatitas). La composición mineral (con destacado contenido en anfíboles de composición hornblenda pargasítica) y la Geoquímica, definen una afinidad calco-alcalina cuya signatura en elementos mayores y trazas, es bastante análoga a la óbtenida en lamprófidos similares, emplazados en macizos granodioríticos. Esta afinidad presenta una relación genética con la granodiorita, como término volumétricamente más representativo del Macizo.[Abstract] Lamprophyric dykes (Spessartites) are frequent in the Maladeta circumscribe plutonic massif (Central Pyrenees, Huesca-Lérida). The setting of these dykes, under confinant strains and with a structural control, affected to á1l the plutonic rocktypes (Quanz-Gabbros, Granodiorites, Tonalites and Syenogranites) and to the acid dykes (Aplites and Pegmatites) too. The mineral (with high contents in Pargasitic-Hornblende amphiboles) and geochemical compositions, define a calc-alkaline affinity, very similar (Major and trace elements) to that of analogue lan prophyres, set in Granodioritic massifs. This affinity shows a genetic relation with the Granodiorite, as volumetrically most representative rock-type in the massif