Quantumness beyond quantum mechanics

Bohmian mechanics allows us to understand quantum systems in the light of other quantum traits than the well-known ones (coherence, diffraction, interference, tunneling, discreteness, entanglement, etc.). Here the discussion focusses precisely on two of these interesting aspects, which arise when quantum mechanics is though within this theoretical framework: the non-crossing property, which allows for distinguishability without erasing interference patterns, and the possibility to define quantum probability tubes, along which the probability remains constant all the way. Furthermore, taking into account this hydrodynamic-like description as a link, it is also shown how this knowledge (concepts and ideas) can be straightforwardly transferred to other fields of physics (for example, the transmission of light along waveguides).Comment: 11 pages, 4 figures; based on a talk at the Conference "Emergent Quantum Mechanics" / 5th Heinz von Foerster Congress (Vienna, Nov 11-13, 2011

Effect of stellar flares on the upper atmospheres of HD 189733b and HD 209458b

Stellar flares are a frequent occurrence on young low-mass stars around which many detected exoplanets orbit. Flares are energetic, impulsive events, and their impact on exoplanetary atmospheres needs to be taken into account when interpreting transit observations. We have developed a model to describe the upper atmosphere of Extrasolar Giant Planets (EGPs) orbiting flaring stars. The model simulates thermal escape from the upper atmospheres of close-in EGPs. Ionisation by solar radiation and electron impact is included and photochemical and diffusive transport processes are simulated. This model is used to study the effect of stellar flares from the solar-like G star HD209458 and the young K star HD189733 on their respective planets. A hypothetical HD209458b-like planet orbiting the active M star AU Mic is also simulated. We find that the neutral upper atmosphere of EGPs is not significantly affected by typical flares. Therefore, stellar flares alone would not cause large enough changes in planetary mass loss to explain the variations in HD189733b transit depth seen in previous studies, although we show that it may be possible that an extreme stellar proton event could result in the required mass loss. Our simulations do however reveal an enhancement in electron number density in the ionosphere of these planets, the peak of which is located in the layer where stellar X-rays are absorbed. Electron densities are found to reach 2.2 to 3.5 times pre-flare levels and enhanced electron densities last from about 3 to 10 hours after the onset of the flare. The strength of the flare and the width of its spectral energy distribution affect the range of altitudes that see enhancements in ionisation. A large broadband continuum component in the XUV portion of the flaring spectrum in very young flare stars, such as AU Mic, results in a broad range of altitudes affected in planets orbiting this star.Comment: accepted for publication in A&

Protein adsorption onto Fe3O4 nanoparticles with opposite surface charge and its impact on cell uptake

Nanoparticles (NPs) engineered for biomedical applications are meant to be in contact with protein-rich physiological fluids. These proteins are usually adsorbed onto the NP surface, forming a swaddling layer called protein corona that influences cell internalization. We present a study on protein adsorption onto different magnetic NPs (MNPs) when immersed in cell culture medium, and how these changes affect the cellular uptake. Two colloids with magnetite cores of 25 nm, same hydrodynamic size and opposite surface charge were in situ coated with (a) positive polyethyleneimine (PEI-MNPs) and (b) negative poly(acrylic acid) (PAA-MNPs). After few minutes of incubation in cell culture medium the wrapping of the MNPs by protein adsorption resulted in a 5-fold size increase. After 24 h of incubation large MNP-protein aggregates with hydrodynamic sizes 1500 to 3000 nm (PAA-MNPs and PEI-MNPs respectively) were observed. Each cluster contained an estimated number of magnetic cores between 450 and 1000, indicating the formation of large aggregates with a "plum pudding" structure of MNPs embedded into a protein network of negative surface charge irrespective of the MNP_core charge. We demonstrated that PEI-MNPs are incorporated in much larger amounts than the PAA-MNPs units. Quantitative analysis showed that SH-SY5Y cells can incorporate 100 per cent of the added PEI-MNPs up to about 100 pg per cell, whereas for PAA-MNPs the uptake was less than 50 percent. The final cellular distribution showed also notable differences regarding partial attachment to the cell membrane. These results highlight the need to characterize the final properties of MNPs after protein adsorption in biological media, and demonstrate the impact of these properties on the internalization mechanisms in neural cells.Comment: 32 pages, 10 figure

Millimeter Wave Substrate Integrated Waveguide Antennas: Design and Fabrication Analysis

The paper presents a new concept in antenna design, whereby a photo-imageable thick-film process is used to integrate a waveguide antenna within a multilayer structure. This has yielded a very compact, high performance antenna working at high millimeter-wave (mm-wave) frequencies, with a high degree of repeatability and reliability in antenna construction. Theoretical and experimental results for 70 GHz mm-wave integrated antennas, fabricated using the new technique are presented. The antennas were formed from miniature slotted waveguide arrays using up to 18 layers of photo-imageable material. To enhance the electrical performance a novel folded waveguide array was also investigated. The fabrication process is analysed in detail and the critical issues involved in the fabrication cycle are discussed. The losses in the substrate integrated waveguide have been calculated. The performance of the new integrated antenna is compared to conventional metallic, air-filled waveguide antennas, and also to conventional microstrip antenna arrays operating at the same frequencies

Estimation of comprehensive two-dimensional gas chromatographic response from one-dimensional gas chromatography data

Trabajo presentado a la XV Reunión Científica de la Sociedad Española de Cromatografía y Técnicas Afines (SECyTA) celebrada en Castellón de la Plana del 28 al 30 de octubre de 2015Optimization of a separation in comprehensive two-dimensional gas chromatography (GC×GC) requires the selection of an appropriate set column, and the optimisation of their respective dimensions, temperature programs and flow rates. Until not so long ago, a time consuming trial and error process was the only way to select the columns and chromatographic conditions for the two GC dimensions. During the last few years, several attempts have been proposed to estimate the chromatographic response in GC×GC [1-4]. Although most of these methods are helpful contributions, some of them focussed exclusively on the retention time estimation and do not consider the effect of peak width, also essential for a correct prediction of the chromatographic separation capability. Others are based on theoretical formulas not applicable to the extreme experimental conditions used in GC×GC, or are only valid for specific types of compounds or stationary phases: these models cannot be corrected for different separation problems. In this work, modelization of retention time and peak width has been carried out from experimental 1D GC data in order to estimate the response in GC×GC separation for different column sets operated under different flows and temperatures. Several theoretical and experimental models are proposed for estimation of 1D and 2D retention time and peak width; in experimental models, 1D GC data are required together with information on column characteristics and operation conditions. Models for hold-up time, retention factor and peak width were first validated in 1D GC from the fit between experimental and calculated data. Their validation in GC×GC was carried out by using n-alkanes and a mixture of disaccharides as their trimethylsilyl oxime derivatives. Comparison of experimental and estimated data showed good results for retention time in both first and second dimension. Peak widths presented, however, some errors, caused by the no consideration on estimation of the effect of the modulator or the rather unusual chromatographic conditions used. The developed programme is very versatile as it can be used for the calculation of the chromatographic response of compounds with different polarity and volatility, analysed under different pressures and temperature ramps, and with different sets of columns. [1] J.V. Seeley, E.M. Libby, K.A.H. Edwards, S.K. Seeley, J. Chromatogr. A 1216 (2009) 1650. [2] F.L. Dorman, P.D. Schettler, L.A. Vogt, J.W. Cochran, J. Chromatogr. A 1186 (2008) 196. [3] Y. Zhao, J. Zhang, B. Wang, S.H. Kim, A. Fang, B. Bogdanov, Z. Zhou, C. McClain, X. Zhang, J. Chromatogr. A 1218 (2011) 2577. [4] S. Zhu, S. He, D.R. Worton, A.H. Goldstein, J. Chromatogr. A 1233 (2012) 147. Acknowledgements: This work has been funded by Ministerio de Economía y Competitividad (project CTQ2012-32957), Comunidad Autónoma de Madrid (Spain) and European funding from FEDER program (AVANSECAL-CM S2013/ABI-3028) and Fundación Ramón Areces. ACS thanks Ministerio de Economía y Competitividad of Spain for a Ramón y Cajal contract.CTQ2012-32957Peer reviewe