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

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

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

Optical instrument for the study of time recovery from total disability glare vision

Disability glare is defined as the loss of contrast sensitivity of the retinal image due to intraocular straylight originated from the presence of an intense and broad bright light in the field of vision. This loss of vision can range between vision loss at high spatial frequencies or total temporal blindness. If the extreme case occurs, the recovery time is crucial in night driving conditions or those professional activities in which maximum visual acuity is required at any moment. The recovery time depends mainly on the intensity and glare angle of the light source, ocular straylight, and the photoreceptor response at the retina. The recovery time can also be affected by ocular pathologies, aging, or physiological factors that increase ocular straylight. The aim of this work is to develop a new optical instrument based on psychophysical methodology as well as to investigate the recovery time from total disability glare (photobleaching) as a function of the contrast of the visual target and the glare angle of the source in healthy volunteers. Results showed significant exponential correlation between recovery time and contrast of the visual target and linear correlation between contrast sensitivity and the glare angle. Those findings allowed to obtain an empirical expression to compute the recovery time required to restore contrast sensitivity baseline vision after photobleaching. Finally, a statistical dependence of recovery time with age was found for short glare angles that disappear as the glare angle increases

Choice of Product Variety for the Durable Goods Monopolist

This paper analyzes the strategic choice of variety by a monopolist seller of a durable good as a means to mitigate his commitment problem. The monopolist chooses his product variety with a goal of ensuring that a strong reduction in future prices will not be profitable because it allows the firm to attract few additional consumers. The main result that emerges from considering product variety as an endogenous variable is that, contrary to the case in which it is exogenously determined, social welfare is always higher when the monopolist cannot commit that when he can.durable goods monopolist, commitment, product variety

Exploring the neural correlates of e-Assurance and multi-faced risk in e-Commerce

El comercio electrónico ha permitido a multitud de pequeñas empresas exponer sus productos y aumentar su público objetivo potencial. Pese a la relativa facilidad de introducirse en este mercado, la mayor dificultad estriba en eliminar las barreras que limitan a los consumidores comprar online. Una de las vías que poseen mayor potencial para aumentar la confianza online y reducir el riesgo percibido es dotar a su web de señales de confianza, entre las que destacan los certificados externos, ratings de consumidores y políticas de privacidad. Este estudio precisamente usa una técnica neurocientífica (resonancia magnética funcional) junto a cuestionarios con el propósito de esclarecer objetivamente el procesamiento neurológico de esas tres señales de seguridad online. Además, usando estas nuevas herramientas, pretende dilucidar la debatida dimensionalidad del riesgo percibido. Los resultados aconsejarán a comercios online la señal más útil a incluir en sus webs y se concretarán las dimensiones del riesgo percibido.E-commerce has allowed many small firms sell their products and broaden their target. Despite the relative ease in which vendors enter this marketplace, the strongest difficulty is to decrease barriers which discourage online purchases. One of the most useful ways to increase consumer online trust and reduce perceived risk is creating trust mechanisms in web sites, such as seals of approval, consumer ratings and privacy policies. Specifically, this study applies a neuroscientific tool (functional magnetic resonance imaging- fMRI-) together with questionnaires with the aim to clear up the neural processing of those trust signals (e-assurances). Furthermore, using fMRI, we explore the “under-debated” dimensionality of perceived risk. The findings will advise online retailers with the most useful e-assurance to include in their websites as well as will specify the dimensions of perceived risk

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

Chiroptical Spectroscopy of C3 Molecules

The relevance of molecules with C3 symmetry comes from the fact of many of them, upon assembling as columnar helical macromolecules, are ideal platform for electro-optical devices, for example as liquid crystals. The properties of these devices are highly dependent of the structure of the bulk aggregates, and consequently they can be controlled by modifying the position and nature of the stereocenters in the molecular building blocks. In this work we present an electronic and vibrational chiroptical study on a series of star-shaped molecules based on the octopolar C3-symmetric 1,3,5-(phenylene-ethynylene)-benzene block.Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tec

Partial ownership of local firms and zoning of neighboring towns

Texto completoThis paper investigates zoning in two neighboring towns in which firms are owned by investors that reside in the two towns. We find that local regulators use zoning strategically depending on the weight of local profits in social welfare. When they are high enough both towns are zoned. For intermediate values an asymmetric result emerges: only one regulator resorts to zoning despite the symmetry in the percentage of ownership of the neighboring firms. For a low weight of local profits, towns may or may not be zoned. Zoning restrictions on the location of firms are tighter when local profits are more significant for social welfare.Ministerio de Ciencia y Tecnología (ECO2015-66803-P) y University of the Basque Country, UPV/EHU (GIU17/051)