Surface nanopatterning by ion beam irradiation: compositional effects

Surface nanopatterning induced by ion beam irradiation (IBI) has emerged as an effective nanostructuring technique since it induces patterns on large areas of a wide variety of materials, in short time, and at low cost. Nowadays, two main subfields can be distinguished within IBI nanopatterning depending on the irrelevant or relevant role played by the surface composition. In this review, we give an up-dated account of the progress reached when surface composition plays a relevant role, with a main focus on IBI surface patterning with simultaneous co-deposition of foreign atoms. In addition, we also review the advances in IBI of compound surfaces as well as IBI systems where the ion employed is not a noble gas species. In particular, for the IBI with concurrent metal co-deposition, we detail the chronological evolution of these studies because it helps us to clarify some contradictory early reports. We describe the main patterns obtained with this technique as a function of the foreign atom deposition pathway, also focusing in those systematic studies that have contributed to identify the main mechanisms leading to the surface pattern formation and development. Likewise, we explain the main theoretical models aimed at describing these nanopattern formation processes. Finally, we address two main special features of the patterns induced by this technique, namely, the enhanced pattern ordering and the possibility to produce both morphological and chemical patterns.This work was supported by Ministerio de Economía, Industria y Competitividad (MINECO, Spain), Agencia Estatal de Investigación (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grant No. PGC2018-094763-B-I00, and by Comunidad de Madrid (Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors, No. EPUC3M23, in the context of the V Plan Regional de Investigación Científica e Innovación Tecnológica (PRICIT), as well as under the TRANSNANOAVANSENS program (S2018-NMT-4349)

Two-dimensional tunneling in a SQUID

Traditionally quantum tunneling in a static SQUID is studied on the basis of a classical trajectory in imaginary time under a two-dimensional potential barrier. The trajectory connects a potential well and an outer region crossing their borders in perpendicular directions. In contrast to that main-path mechanism, a wide set of trajectories with components tangent to the border of the well can constitute an alternative mechanism of multi-path tunneling. The phenomenon is essentially non-one-dimensional. Continuously distributed paths under the barrier result in enhancement of tunneling probability. A type of tunneling mechanism (main-path or multi-path) depends on character of a state in the potential well prior to tunneling.Comment: 9 pages, 8 figure

Combining 4D Flow MRI and Complex Networks Theory to Characterize the Hemodynamic Heterogeneity in Dilated and Non-dilated Human Ascending Aortas

Motivated by the evidence that the onset and progression of the aneurysm of the ascending aorta (AAo) is intertwined with an adverse hemodynamic environment, the present study characterized in vivo the hemodynamic spatiotemporal complexity and organization in human aortas, with and without dilated AAo, exploring the relations with clinically relevant hemodynamic and geometric parameters. The Complex Networks (CNs) theory was applied for the first time to 4D flow magnetic resonance imaging (MRI) velocity data of ten patients, five of them presenting with AAo dilation. The time-histories along the cardiac cycle of velocity-based quantities were used to build correlation-based CNs. The CNs approach succeeded in capturing large-scale coherent flow features, delimiting flow separation and recirculation regions. CNs metrics highlighted that an increasing AAo dilation (expressed in terms of the ratio between the maximum AAo and aortic root diameter) disrupts the correlation in forward flow reducing the correlation persistence length, while preserving the spatiotemporal homogeneity of secondary flows. The application of CNs to in vivo 4D MRI data holds promise for a mechanistic understanding of the spatiotemporal complexity and organization of aortic flows, opening possibilities for the integration of in vivo quantitative hemodynamic information into risk stratification and classification criteria

Phase‐amplitude coupling profiles differ in frontal and auditory cortices of bats

Neural oscillations are at the core of important computations in the mammalian brain. Interactions between oscillatory activities in different frequency bands, such as delta (1–4 Hz), theta (4–8 Hz) or gamma (>30 Hz), are a powerful mechanism for binding fundamentally distinct spatiotemporal scales of neural processing. Phase‐amplitude coupling (PAC) is one such plausible and well‐described interaction, but much is yet to be uncovered regarding how PAC dynamics contribute to sensory representations. In particular, although PAC appears to have a major role in audition, the characteristics of coupling profiles in sensory and integration (i.e. frontal) cortical areas remain obscure. Here, we address this question by studying PAC dynamics in the frontal‐auditory field (FAF; an auditory area in the bat frontal cortex) and the auditory cortex (AC) of the bat Carollia perspicillata. By means of simultaneous electrophysiological recordings in frontal and auditory cortices examining local‐field potentials (LFPs), we show that the amplitude of gamma‐band activity couples with the phase of low‐frequency LFPs in both structures. Our results demonstrate that the coupling in FAF occurs most prominently in delta/high‐gamma frequencies (1‐4/75‐100 Hz), whereas in the AC the coupling is strongest in the delta‐theta/low‐gamma (2‐8/25‐55 Hz) range. We argue that distinct PAC profiles may represent different mechanisms for neuronal processing in frontal and auditory cortices, and might complement oscillatory interactions for sensory processing in the frontal‐auditory cortex network

Echolocation-related reversal of information flow in a cortical vocalization network

The mammalian frontal and auditory cortices are important for vocal behavior. Here, using local-field potential recordings, we demonstrate that the timing and spatial patterns of oscillations in the fronto-auditory network of vocalizing bats (Carollia perspicillata) predict the purpose of vocalization: echolocation or communication. Transfer entropy analyses revealed predominant top-down (frontal-to-auditory cortex) information flow during spontaneous activity and pre-vocal periods. The dynamics of information flow depend on the behavioral role of the vocalization and on the timing relative to vocal onset. We observed the emergence of predominant bottom-up (auditory-to-frontal) information transfer during the post-vocal period specific to echolocation pulse emission, leading to self-directed acoustic feedback. Electrical stimulation of frontal areas selectively enhanced responses to sounds in auditory cortex. These results reveal unique changes in information flow across sensory and frontal cortices, potentially driven by the purpose of the vocalization in a highly vocal mammalian model

The AMS-02 RICH Imager Prototype - In-Beam Tests with 20 GeV/c per Nucleon Ions -

A prototype of the AMS Cherenkov imager (RICH) has been tested at CERN by means of a low intensity 20 GeV/c per nucleon ion beam obtained by fragmentation of a primary beam of Pb ions. Data have been collected with a single beam setting, over the range of nuclear charges 2<Z<~45 in various beam conditions and using different radiators. The charge Z and velocity beta resolutions have been measured.Comment: 4 pages, contribution to the ICRC 200

Global fits to neutrino oscillation data

I summarize the determination of neutrino oscillation parameters within the three-flavor framework from world neutrino oscillation data with date of May 2006, including the first results from the MINOS long-baseline experiment. It is illustrated how the determination of the leading "solar" and "atmospheric" parameters, as well as the bound on $\theta_{13}$ emerge from an interplay of various complementary data sets. Furthermore, I discuss possible implications of sub-leading three-flavor effects in present atmospheric neutrino data induced by $\Delta m^2_{21}$ and $\theta_{13}$ for the bound on $\theta_{13}$ and non-maximal values of $\theta_{23}$, emphasizing, however, that these effects are not statistically significant at present. Finally, in view of the upcoming MiniBooNE results I briefly comment on the problem to reconcile the LSND signal.Comment: 5 pages, 5 figures, talk presented at the SNOW2006 workshop, Stockholm, 2-6 May 200

El futuro de las revistas científicas españolas: un esfuerzo científico, social e institucional

In spite of the increasingly high level of scientific production by Spanish researchers on terrestrial vertebrate biology, Spanish journals on this topic are, paradoxically, in a delicate situation that seriously threatens their future. This paper surnrnarises the results obtained in an analysis of the current situation of these journals and their perspectives for the near future: Such results are fully applicable to most scientific journals edited both in Spain and in countries in a similar situation. The international status of a journal determines the quality and quantity of original works that receives and publishes. The quality of the published papers was, in turn, the rnain deterrnining factor of this international status until the appearance of the "impact factors" elaborated by a private company, the North American lnstitute for Scientific lnformation (ISI), The ISI also elaborates a list of journals classified according to their irnpact factors, as well as to a nurnber of inclusion criteria. In spite of the fact that both the irnpact factors and the criteria for inclusion of journals are now under close scrutiny by the scientific cornrnunity, journals not included on this list are considered "non-prestigious". The future of such journals is thus threatened as this " label" prevents scientists frorn subrnitting their good quality papers to thern. Few Spanish scientific journals are included on the list, and the ISI is reluctant to lengthen it unless the journals are new, published in English and, usually, supported by the major publishing houses which monopolise the international rnarket of scientific publications. Most Spanish scientific journals, especially those focused on terrestrial vertebrates, are published by scientific societies integrated by both professional scientists and naturalists interested in the study of these organisrns. The Spanish Administration partially supported some of them in the past through specific funding. In addition, sorne journals were fully supported by public funds, but they have either disappeared or are not published periodically. This situation contradicts the governrnent's objectives to prornote the Spanish language and to obtain returns on the investment in training high-level scientists. On this basis, one way to ensure the long-term rnaintenance of Spanish journals would be to enhance alternatives such as the publication of local studies or the support and training of novel scientists. This option may be carried out by scientific societies thernselves without institutional aid by means of ¡.e. reducing the subscription cost, as far as some disagreernents between the scientific and non-scientific partners were solved properly. However, this would limit the international projection of the Spanish journals. The only alternative would be a social, institutional and political agreement aimed at promoting those Spanish journals, either already established or new, with the best perspectives for international diffusion. The final goal should be the inclusion of these journals on the ISI list. The co-ordinated efforts of scientists, scientific societies and the administration would thus eventually reach the objective of maintaining high-quality scientific journals, one of the main mid-term returns on the investment in science. Key words: Problems for long-term maintenance, Scientific journals, Scientific policy, Scientific societies, Social and institutional support, Terrestrial vertebrates.In spite of the increasingly high level of scientific production by Spanish researchers on terrestrial vertebrate biology, Spanish journals on this topic are, paradoxically, in a delicate situation that seriously threatens their future. This paper surnrnarises the results obtained in an analysis of the current situation of these journals and their perspectives for the near future: Such results are fully applicable to most scientific journals edited both in Spain and in countries in a similar situation. The international status of a journal determines the quality and quantity of original works that receives and publishes. The quality of the published papers was, in turn, the rnain deterrnining factor of this international status until the appearance of the "impact factors" elaborated by a private company, the North American lnstitute for Scientific lnformation (ISI), The ISI also elaborates a list of journals classified according to their irnpact factors, as well as to a nurnber of inclusion criteria. In spite of the fact that both the irnpact factors and the criteria for inclusion of journals are now under close scrutiny by the scientific cornrnunity, journals not included on this list are considered "non-prestigious". The future of such journals is thus threatened as this " label" prevents scientists frorn subrnitting their good quality papers to thern. Few Spanish scientific journals are included on the list, and the ISI is reluctant to lengthen it unless the journals are new, published in English and, usually, supported by the major publishing houses which monopolise the international rnarket of scientific publications. Most Spanish scientific journals, especially those focused on terrestrial vertebrates, are published by scientific societies integrated by both professional scientists and naturalists interested in the study of these organisrns. The Spanish Administration partially supported some of them in the past through specific funding. In addition, sorne journals were fully supported by public funds, but they have either disappeared or are not published periodically. This situation contradicts the governrnent's objectives to prornote the Spanish language and to obtain returns on the investment in training high-level scientists. On this basis, one way to ensure the long-term rnaintenance of Spanish journals would be to enhance alternatives such as the publication of local studies or the support and training of novel scientists. This option may be carried out by scientific societies thernselves without institutional aid by means of ¡.e. reducing the subscription cost, as far as some disagreernents between the scientific and non-scientific partners were solved properly. However, this would limit the international projection of the Spanish journals. The only alternative would be a social, institutional and political agreement aimed at promoting those Spanish journals, either already established or new, with the best perspectives for international diffusion. The final goal should be the inclusion of these journals on the ISI list. The co-ordinated efforts of scientists, scientific societies and the administration would thus eventually reach the objective of maintaining high-quality scientific journals, one of the main mid-term returns on the investment in science. Key words: Problems for long-term maintenance, Scientific journals, Scientific policy, Scientific societies, Social and institutional support, Terrestrial vertebrates.In spite of the increasingly high level of scientific production by Spanish researchers on terrestrial vertebrate biology, Spanish journals on this topic are, paradoxically, in a delicate situation that seriously threatens their future. This paper surnrnarises the results obtained in an analysis of the current situation of these journals and their perspectives for the near future: Such results are fully applicable to most scientific journals edited both in Spain and in countries in a similar situation. The international status of a journal determines the quality and quantity of original works that receives and publishes. The quality of the published papers was, in turn, the rnain deterrnining factor of this international status until the appearance of the "impact factors" elaborated by a private company, the North American lnstitute for Scientific lnformation (ISI), The ISI also elaborates a list of journals classified according to their irnpact factors, as well as to a nurnber of inclusion criteria. In spite of the fact that both the irnpact factors and the criteria for inclusion of journals are now under close scrutiny by the scientific cornrnunity, journals not included on this list are considered "non-prestigious". The future of such journals is thus threatened as this " label" prevents scientists frorn subrnitting their good quality papers to thern. Few Spanish scientific journals are included on the list, and the ISI is reluctant to lengthen it unless the journals are new, published in English and, usually, supported by the major publishing houses which monopolise the international rnarket of scientific publications. Most Spanish scientific journals, especially those focused on terrestrial vertebrates, are published by scientific societies integrated by both professional scientists and naturalists interested in the study of these organisrns. The Spanish Administration partially supported some of them in the past through specific funding. In addition, sorne journals were fully supported by public funds, but they have either disappeared or are not published periodically. This situation contradicts the governrnent's objectives to prornote the Spanish language and to obtain returns on the investment in training high-level scientists. On this basis, one way to ensure the long-term rnaintenance of Spanish journals would be to enhance alternatives such as the publication of local studies or the support and training of novel scientists. This option may be carried out by scientific societies thernselves without institutional aid by means of ¡.e. reducing the subscription cost, as far as some disagreernents between the scientific and non-scientific partners were solved properly. However, this would limit the international projection of the Spanish journals. The only alternative would be a social, institutional and political agreement aimed at promoting those Spanish journals, either already established or new, with the best perspectives for international diffusion. The final goal should be the inclusion of these journals on the ISI list. The co-ordinated efforts of scientists, scientific societies and the administration would thus eventually reach the objective of maintaining high-quality scientific journals, one of the main mid-term returns on the investment in science. Key words: Problems for long-term maintenance, Scientific journals, Scientific policy, Scientific societies, Social and institutional support, Terrestrial vertebrates