VCD helps others in molecular aggregates

Molecular self-assembly is the driving force of a great number of physical, chemical and biological processes in Nature.1 The properties of the molecular aggregates are markedly dependent on the intermolecular forces which hold together the building blocks, but also on the chemical and structural features of these building blocks. The transference of properties from the individual molecules to the bulk aggregate can be summarized in three main behaviours: disappearance (dipole moment), direct sum (weight) and enhancement (resilience). A nice example of the last group is the optical activity. The presence of a chiral seed in the molecules modulates their folding by favouring one among the available macrostructures. As a consequence, new forms of supramolecular chirality are triggered, such as helical, spiral or chiral sheets, which usually give rise to a noticeable increasing of the chiral signal of the aggregates. Vibrational circular dichroism (VCD) is the chiral version of infrared spectroscopy. It combines the intramolecular view provided by the molecular vibrations with the selective capability of a chiral analysis. It is also a suitable technique to observe the aggregation-induced signal enhancement in any type of condensed phase (solid, liquid, gel, etc). Here we present a series of studies on supramolecular systems, Figure 1, in which VCD helps and improves the analysis obtained by other techniques of chiral analysis as electron microscopy (SEM, AFM), electronic circular dichroism (ECD), Raman optical activity (ROA) or circularly polarized luminescence (CPL). These studies are aimed to obtain structural information of the macromolecular scaffolding useful to control the features and applications of the aggregates.Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tec

Physics of beer tapping

The popular bar prank known in colloquial English as beer tapping consists in hitting the top of a beer bottle with a solid object, usually another bottle, to trigger the foaming over of the former within a few seconds. Despite the trick being known for long time, to the best of our knowledge, the phenomenon still lacks scientific explanation. Although it seems natural to think that shock-induced cavitation enhances the diffusion of CO$_2$ from the supersaturated bulk liquid into the bubbles by breaking them up, the subtle mechanism by which this happens remains unknown. Here we show that the overall foaming-over process can be divided into three stages where different physical phenomena take place in different time-scales, namely: bubble-collapse (or cavitation) stage, diffusion-driven stage and buoyancy-driven stage. In the bubble-collapse stage, the impact generates a train of expansion-compression waves in the liquid that leads to the fragmentation of pre-existing gas cavities. Upon bubble fragmentation, the sudden increase of the interface-area-to-volume ratio enhances mass transfer significantly, which makes the bubble volume grow by a large factor until CO$_2$ is locally depleted. At that point buoyancy takes over, making the bubble clouds rise and eventually form buoyant vortex rings whose volume grows fast due to the feedback between the buoyancy-induced rising speed and the advection-enhanced CO$_2$ transport from the bulk liquid to the bubble. The physics behind this explosive process might also be connected to some geological phenomena.Comment: 7 pages, 4 figures, 4 movies Accepted in Physical Review Letter

About Helices and Solvents: VCD and more

Intermolecular forces drive self-organization of molecules, which is ultimately the origin of most the physical and chemical phenomena in Nature. Molecules able to interact themselves by non-covalent forces, as hydrogen bonding and/or hydrophobic attractions, usually form macrostructures in condensed phases (solid, solution). The properties of these aggregates depend of three main factors: the structural and chemical features of the molecules, the nature of intermolecular forces and the environment. The first two drive aggregation in solid state, while in solution the role of the solvent become determinant as it can induce a variety of structural effects on the aggregation behaviour of the solute. In the case of chiral molecules, this property is transferred to the aggregates and supramolecular chirality appears. Here we present our research on chiral molecules that self-organize in solution forming helical structures. We use VCD as the main chiroptical tool, but also supported by other chiroptical spectroscopies (ECD, ROA) and theoretical modelling. In our first steps, we studied the effect of modulating the environmental settings on the helices. Thus, helix handedness was proved highly and reversibly dependent on factors as pH or ionic strength in peptide-mimetic hydrogelators. We also observe how the initial conditions (concentration, temperature) were capable of controlling the helix structure of oligo-p-phenylene-based polymers towards kinetic or thermodynamics pathways. Besides, the structure of the helices can also be the consequence of direct solvent-solute interactions. In this way, we have demonstrated that an achiral solvent can act as a template for chiral organization of N-heterotriangulenes-based organogelators, thus showing the different levels of complexity of the hierarchical organization of supramolecular polymers. But the solvent-helix interactions can be bidirectional. As a nice example, we recorded chiral signals which can be only assigned to the organization of the solvent molecules around helical aggregates of phenylglycine functionalized poly(phenylacetylene)s. The solvent molecules thus form a first solvation shell to which the helix chirality is transferred. The helices would act therefore as a template of the solvent molecules, and the chirality of this external helix would be fully controlled by the solute.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Should Owners of Firms Delegate Long-run Decisions?

This paper analyzes whether owners of firms have incentives to delegate their long-run decisions to managers or not. The result arising from our analysis shows that owners do have incentives to keep their long-run decisions (the location of the firm) to themselves. In this context we show that the delegation of short-run decisions (prices) to the managers leads to an increase in the degree of product differentiation with regard to the case in which firms do not hire managers.managerial incentives, strategic delegation, product differentiation

Reducing Self-Stigma in People with Severe Mental Illness Participating in a Regular Football League: An Exploratory Study

For the past 15 years, a regular indoor football competition has been taking place in Madrid (Spain) with 15 teams from different mental health services in the city, in which teams face off weekly as part of a competition lasting nine months of the year. We are not aware of whether a similar competition experience is offered in other cities. The purpose of the present study was to evaluate whether participating in this league, called Ligasame, has an influence on participants’ self-stigma. To do so, the Internalized Stigma of Mental Illness scale (ISMI) was adapted into Spanish and applied to 108 mental health patients, 40% of which participated in Ligasame, and the remainder of which did not. The results obtained reflect significant differences between those participating in Ligasame and those that did not in terms of two specific dimensions related to self-stigma (stereotype endorsement and stigma resistance) and total score. On the other hand, no significant differences were found in terms of other variables, such as patients’ prior diagnosis, age or belonging to different resources/associations. In this article, we discuss the importance of these results in relation to reducing self-stigma through participation in a regular yearly mental health football league

Atención plena en la adolescencia. Determinantes sociodemográficos y su relación con los modelos de apego

La atención plena hace referencia a la capacidad para centrarse en el momento presente de forma reflexiva y activa. El estudio de esta capacidad en la población adolescente está en auge en las últimas dos décadas. Esto se debe principalmente a los beneficios que conlleva un alto nivel de atención plena en dicha población. Diversos estudios se centran en la aplicación de programas de atención plena con consecuencias muy positivas. Sin embargo, este estudio se centra en el aspecto descriptivo, explorando la relación que la atención plena puede tener con algunas variables sociodemográficas (edad, género, rendimiento académico y nivel académico de los progenitores) y la relación con un concepto muy estudiado en el área de la Psicología Evolutiva, el apego. Para este propósito, un total de 112 adolescentes con edades comprendidas entre los 12 y 15 años (M = 13.46, DT = 1.06) participaron en el estudio. Los resultados mostraron que no existía una relación significativa entre el nivel de atención plena de los adolescentes y las variables sociodemográficas seleccionadas en el estudio, aunque sí se observó una clara relación entre esta capacidad y los modelos de apego de la población adolescente.Universidad de Sevilla. Grado en Psicologí

The Rival Coffee Shop Problem

We show some estimations for the Coffee Shop Problem with a modification respect the original statement: there is a rival competing against us. We present different results based on how fast the rival is able to grow. As main tool, we use a variation of the Wasserstein distance (Generalized Signed Wasserstein Distance), that allow us to work with finite signed measures

High-Performance low-vcc in-order core

Power density grows in new technology nodes, thus requiring Vcc to scale especially in mobile platforms where energy is critical. This paper presents a novel approach to decrease Vcc while keeping operating frequency high. Our mechanism is referred to as immediate read after write (IRAW) avoidance. We propose an implementation of the mechanism for an Intel® SilverthorneTM in-order core. Furthermore, we show that our mechanism can be adapted dynamically to provide the highest performance and lowest energy-delay product (EDP) at each Vcc level. Results show that IRAW avoidance increases operating frequency by 57% at 500mV and 99% at 400mV with negligible area and power overhead (below 1%), which translates into large speedups (48% at 500mV and 90% at 400mV) and EDP reductions (0.61 EDP at 500mV and 0.33 at 400mV).Peer ReviewedPostprint (published version