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By means of spin- and angle-resolved photoelectron spectroscopy we studied the spin structure of thin films of the topological insulator Bi2Se3 grown on InP(111). For thicknesses below six quintuple layers the spin-polarized metallic topological surface states interact with each other via quantum tunneling and a gap opens. Our measurements show that the resulting surface states can be described by massive Dirac cones which are split in a Rashba-like manner due to the substrate induced inversion asymmetry. The inner and the outer Rashba branches have distinct localization in the top and the bottom part of the film, whereas the band apices are delocalized throughout the entire film. Supported by ab initio calculations, our observations help in the understanding of the evolution of the surface states at the topological phase transition and provide the groundwork for the realization of two-dimensional spintronic devices based on topological semiconductors. © 2014 American Physical Society.

[Background] With more than 100000 living species, mollusks are the second most diverse metazoan phylum. The current taxonomic classification of mollusks recognizes eight classes (Neomeniomorpha, Chaetodermomorpha, Polyplacophora, Monoplacophora, Cephalopoda, Gastropoda, Bivalvia, and Scaphopoda) that exhibit very distinct body plans. In the past, phylogenetic relationships among mollusk classes have been contentious due to the lack of indisputable morphological synapomorphies. Fortunately, recent phylogenetic analyses based on multi-gene data sets are rendering promising results. In this regard, mitochondrial genomes have been widely used to reconstruct deep phylogenies. For mollusks, complete mitochondrial genomes are mostly available for gastropods, bivalves, and cephalopods, whereas other less-diverse lineages have few or none reported., [Results] The complete DNA sequence (14662 bp) of the mitochondrial genome of the chaetodermomorph Scutopus ventrolineatus Salvini-Plawen, 1968 was determined. Compared with other mollusks, the relative position of protein-coding genes in the mitochondrial genome of S. ventrolineatus is very similar to those reported for Polyplacophora, Cephalopoda and early-diverging lineages of Bivalvia and Gastropoda (Vetigastropoda and Neritimorpha; but not Patellogastropoda). The reconstructed phylogenetic tree based on combined mitochondrial and nuclear sequence data recovered monophyletic Aplacophora, Aculifera, and Conchifera. Within the latter, Cephalopoda was the sister group of Gastropoda and Bivalvia + Scaphopoda., [Conclusions] Phylogenetic analyses of mitochondrial sequences showed strong among-lineage rate heterogeneity that produced long-branch attraction biases. Removal of long branches (namely those of bivalves and patellogastropods) ameliorated but not fully resolved the problem. Best results in terms of statistical support were achieved when mitochondrial and nuclear sequence data were concatenated.

Dicyanovinyl-quinquethiophene (DCV5T-Me2) is a prototype conjugated oligomer for highly efficient organic solar cells. This class of oligothiophenes are built up by an electron-rich donor (D) backbone and terminal electron-deficient acceptor (A) moieties. Here, we investigated its structural and electronic properties when it is adsorbed on a Au(111) surface using low temperature scanning tunneling microscopy/spectroscopy (STM/STS) and atomic force microscopy (AFM). We find that DCV5T-Me2 self-assembles in extended chains, stabilized by intercalated Au atoms. The effect of metal-ligand hybridization with Au adatoms causes an energetic downshift of the DCV5T-Me2 lowest unoccupied molecular orbital (LUMO) with respect to the uncoordinated molecules on the surface. The asymmetric coordination of a gold atom to only one molecular end group leads to an asymmetric localization of the LUMO and LUMO+1 states at opposite sides. Using model density functional theory (DFT) calculations, we explain such orbital reshaping as a consequence of linear combinations of the original LUMO and LUMO+1 orbitals, mixed by the attachment of a bridging Au adatom. Our study shows that the alignment of molecular orbitals and their distribution within individual molecules can be modified by contacting them to metal atoms in specific sites.

To improve proteome coverage and protein C-terminal identification, we characterized the Methanosarcina acetivorans thermophilic proteinase LysargiNase, which cleaves before lysine and arginine up to 55 °C. Unlike trypsin, LysargiNase-generated peptides had N-terminal lysine or arginine residues and fragmented with b ion-dominated spectra. This improved protein C terminal-peptide identification and several arginine-rich phosphosite assignments. Notably, cleavage also occurred at methylated or dimethylated lysine and arginine, facilitating detection of these epigenetic modifications.

The genus Salamandra represents a clade of six species of Palearctic salamanders of either contrasted black-yellow, or uniformly black coloration, known to contain steroidal alkaloid toxins in high concentrations in their skin secretions. This study reconstructs the phylogeny of the genus Salamandra based on DNA sequences of segments of 10 mitochondrial and 13 nuclear genes from 31 individual samples representing all Salamandra species and most of the commonly recognized subspecies. The concatenated analysis of the complete dataset produced a fully resolved tree with most nodes strongly supported, suggesting that a clade composed of the Alpine salamander (S. atra) and the Corsican fire salamander (S. corsica) is the sister taxon to a clade containing the remaining species, among which S. algira and S. salamandra are sister species. Separate analyses of mitochondrial and nuclear data partitions disagreed regarding basal nodes and in the position of the root but concordantly recovered the S. atra/. S. corsica as well as the S. salamandra/. S. algira relationship. A species-tree analysis suggested almost simultaneous temporal splits between these pairs of species, which we hypothesize was caused by vicariance events after the Messinian salinity crisis (from late Miocene to early Pliocene). A survey of toxins with combined gas chromatography/mass spectroscopy confirmed the presence of samandarine and/or samandarone steroidal alkaloids in all species of Salamandra as well as in representatives of their sister group, Lyciasalamandra. Samandarone was also detected in lower concentrations in other salamandrids including Calotriton, Euproctus, Lissotriton, and Triturus, suggesting that the presence and possible biosynthesis of this alkaloid is plesiomorphic within the Salamandridae. © 2014 Elsevier Inc.

Energy loss from the translational motion of an atom or molecule impinging on a metal surface to the surface may determine whether the incident particle can trap on the surface, and whether it has enough energy left to react with another molecule present at the surface. Although this is relevant to heterogeneous catalysis, the relative extent to which energy loss of hot atoms takes place to phonons or electron-hole pair (ehp) excitation, and its dependence on the system's parameters, remain largely unknown. We address these questions for two systems that present an extreme case of the mass ratio of the incident atom to the surface atom, i.e., H + Cu(111) and H + Au(111), by presenting adiabatic ab initio molecular dynamics (AIMD) predictions of the energy loss and angular distributions for an incidence energy of 5 eV. The results are compared to the results of AIMDEFp calculations modeling energy loss to ehp excitation using an electronic friction (>EF>) model applied to the AIMD trajectories, so that the energy loss to the electrons is calculated >post> (>p>) the computation of the AIMD trajectory. The AIMD calculations predict average energy losses of 0.38 eV for Cu(111) and 0.13-0.14 eV for Au(111) for H-atoms that scatter from these surfaces without penetrating the surface. These energies closely correspond with energy losses predicted with Baule models, which is suggestive of structure scattering. The predicted adiabatic integral energy loss spectra (integrated over all final scattering angles) all display a lowest energy peak at an energy corresponding to approximately 80% of the average adiabatic energy loss for non-penetrative scattering. In the adiabatic limit, this suggests a way of determining the approximate average energy loss of non-penetratively scattered H-atoms from the integral energy loss spectrum of all scattered H-atoms. The AIMDEFp calculations predict that in each case the lowest energy loss peak should show additional energy loss in the range

The quasi two-dimensional electron gas on a metal film can transmit to the surface even minute mechanical disturbances occurring in the depth, thus allowing the gentlest of all surface probes, helium atoms, to perceive the vibrations of the deepest atoms via the induced surface-charge density oscillations. A density functional perturbation theory (DFPT) and a helium atom scattering study of the phonon dispersion curves in lead films of up to 7 mono-layers on a copper substrate show that: (a) the electron-phonon interaction is responsible for the coupling of He atoms to in-depth phonon modes; and (b) the inelastic HAS intensity from a given phonon mode is proportional to its electron-phonon coupling. The direct determination of mode-selected electron-phonon coupling strengths has great relevance for understanding superconductivity in thin films and two-dimensional systems. This journal is © the Partner Organisations 2014.

Aiming at both high energy and power density, asymmetric supercapacitors with screen printed lithium cobalt oxide (LiCoO2) and graphene oxide GO as electrode materials were assembled. LiCoO2 was synthesized by a facile and inexpensive hydrothermal method, whereas GO was synthesized according to a modified Hummer's method. Both powders were coated on flexible stainless steel substrates using screen printing technology. Finally, asymmetric supercapacitors were assembled using LiCoO2 as positive and GO as negative electrode with a porous polypropylene sheet as separator and an aqueous electrolyte solution of LiClO4. The electrochemical properties of this asymmetric cell were investigated by cyclic voltammetry and galvanostatic charge/discharge experiments. The asymmetric supercapacitor LiCoO2//GO could be cycled reversibly in the wide voltage region 0–1.5 V; it shows an impressive performance with an energy density of 19.2 Whkg–1 (based on the total mass of the active materials of the two electrodes). Importantly, this device exhibits an excellent long cycling life with 85 % specific capacitance retained after 1500 cycles. A demonstration cell could effectively light up an LED.

The immune system plays an instrumental role in obesity and insulin resistance. Here, we unravel the role of the costimulatory molecule CD40 and its signaling intermediates, TNF receptor-associated factors (TRAFs), in diet-induced obesity (DIO). Although not exhibiting increased weight gain, male CD40(-/-) mice in DIO displayed worsened insulin resistance, compared with wild-type mice. This worsening was associated with excessive inflammation of adipose tissue (AT), characterized by increased accumulation of CD8(+) T cells and M1 macrophages, and enhanced hepatosteatosis. Mice with deficient CD40-TRAF2/3/5 signaling in MHCII(+) cells exhibited a similar phenotype in DIO as CD40(-/-) mice. In contrast, mice with deficient CD40-TRAF6 signaling in MHCII(+) cells displayed no insulin resistance and showed a reduction in both AT inflammation and hepatosteatosis in DIO. To prove the therapeutic potential of inhibition of CD40-TRAF6 in obesity, DIO mice were treated with a small-molecule inhibitor that we designed to specifically block CD40-TRAF6 interactions; this compound improved insulin sensitivity, reduced AT inflammation, and decreased hepatosteatosis. Our study reveals that the CD40-TRAF2/3/5 signaling pathway in MHCII(+) cells protects against AT inflammation and metabolic complications associated with obesity whereas CD40-TRAF6 interactions in MHCII(+) cells aggravate these complications. Inhibition of CD40-TRAF6 signaling by our compound may provide a therapeutic option in obesity-associated insulin resistance.

The subfamily Rhizomyinae is known from the Late Oligocene up to the present. Today this group comprises six species, which live in southern Asia and eastern Africa. Despite the current moderate diversity of the rhizomyines, they had a greater diversification and wider distribution in the past: from Asia, their land of origin, to Africa, which they entered during the Early Miocene. So far 33 fossil species can be referred to this group. A cladistic analysis involving fossil and living species has been carried out. Prokanisamys spp. turned out to be the most basal taxa of the ingroup. This analysis calls into question the monophyly of several genera, and allows the proposal of a phylogenetic definition of the tribes Tachyoryctini and Rhizomyini. It also provides information about the origin of the African rhizomyines and allows inferring multiple dispersal phenomena from Asia to Africa in Early and Late Miocene times.

We study a supersymmetric version of the type-III seesaw mechanism considering two variants of the model: a minimal version for explaining neutrino data with only two copies of 24 superfields and a model with three generations of 24-plets. The latter predicts, in general, rates for mu -> e gamma inconsistent with experimental data. However, this bound can be evaded if certain special conditions within the neutrino sector are fulfilled. In the case of two 24-plets, lepton flavor violation constraints can be satisfied much more easily. After specifying the corresponding regions in the minimal supergravity parameter space, we show that under favorable conditions one can test the corresponding flavor structures in the leptonic sector at the LHC. For this we perform Monte Carlo studies for the signals, also taking into account the supersymmetry background. We find that it is only of minor importance for the scenarios studied here.

While standard solar model (SSM) predictions depend on approximately 20 input parameters, SSM neutrino flux predictions are strongly correlated with a single model output parameter, the core temperature T-c. Consequently, one can extract physics from solar neutrino flux measurements while minimizing the consequences of SSM uncertainties, by studying flux ratios with appropriate power-law weightings tuned to cancel this T-c dependence. We reexamine an idea for constraining the primordial C + N content of the solar core from a ratio of CN-cycle O-15 to pp-chain B-8 neutrino fluxes, showing that non-nuclear SSM uncertainties in the ratio are small and effectively governed by a single parameter, the diffusion coefficient. We point out that measurements of both CN-I cycle neutrino branches-O-15 and N-13 beta-decay-could, in principle, lead to separate determinations of the core C and N abundances, due to out-of-equilibrium CN-cycle burning in the cooler outer layers of the solar core. Finally, we show that the strategy of constructing "minimum uncertainty" neutrino flux ratios can also test other properties of the SSM. In particular, we demonstrate that a weighted ratio of Be-7 and B-8 fluxes constrains a product of S-factors to the same precision currently possible with laboratory data.

We analyze the recent experimental evidence for an excess of tau-lepton production in several exclusive semileptonic B-meson decays in the context of two-Higgs-doublet models. These decay modes are sensitive to the exchange of charged scalars and constrain strongly their Yukawa interactions. While the usual Type-II scenario cannot accommodate the recent BaBar data, this is possible within more general models in which the charged-scalar couplings to up-type quarks are not as suppressed. Both the B -> D-(*)tau nu(tau) and the B -> tau nu(tau) data can be fitted within the framework of the Aligned Two-Higgs-Doublet Model, but the resulting parameter ranges are in conflict with the constraints from leptonic charm decays. This could indicate a departure from the family universality of the Yukawa couplings, beyond their characteristic fermion mass dependence. We discuss several new observables that are sensitive to a hypothetical charged-scalar contribution, demonstrating that they are well suited to distinguish between different scenarios of new physics in the scalar sector, and also between this group and models with different Dirac structures; their experimental study would therefore shed light on the relevance of scalar exchanges in semileptonic b -> c tau(-)(nu) over bar (tau) transitions.

Alkali-metal (AM) atoms adsorbed on single-crystal surfaces are a model system for understanding the properties of adsorption. AM adsorption, besides introducing new overlayer vibrational states, induces significant modifications in the surface vibrational structure of the metal substrate. Several studies of the vibrational properties of AM on metal surfaces have been carried out in last decades. Most of these investigations have been performed for low coverages of AM in order to make the lateral interaction among co-adsorbates negligible. The adsorbed phase is characterized by a stretch (S) vibrational mode, with a polarization normal to the surface, and by other two modes polarized in the surface plane, known as frustrated translation (T) modes. The frequencies and intensities of these modes depend on the coverage, thus providing a spectroscopic signature for the characterization of the adsorbed phases. The vibrational spectroscopy joined to an ab-initio theoretical analysis can provide useful information about surface charge re-distribution and the nature of the adatom-surface bond, establishing, e.g., its partial ionicity and polarization. Gaining this information implies a significant advancement in our knowledge on surface chemical bonds and on catalytic reactions occurring in AM co-adsorption with other chemical species. Hence, systematic studies of co-adsorption systems are essential for a more complete understanding of heterogeneous catalysis. The two principal experimental techniques for studying the vibrations of AM adsorbed phases are high-resolution electron energy loss spectroscopy (HREELS) and inelastic helium atom scattering (HAS), the former being better suited to the analysis of the higher part of the vibrational spectrum, while the latter exploits its better resolution in the study of slower dynamics, e.g., T modes, surface acoustic phonons and diffusive phenomena. Concerning AM co-adsorption systems, reflection-absorption infrared spectroscopy (R

[Background] The Alpine region harbours one of the most diverse subterranean faunas in the world, with many species showing extreme morphological modifications. The ground beetles of tribe Trechini (Coleoptera, Carabidae) are among the best studied and widespread groups with abundance of troglobionts, but their origin and evolution is largely unknown., [Results] We sequenced 3.4 Kb of mitochondrial (cox1, rrnL, trnL, nad1) and nuclear (SSU, LSU) genes of 207 specimens of 173 mostly Alpine species, including examples of all subterranean genera but two plus a representation of epigean taxa. We applied Bayesian methods and maximum likelihood to reconstruct the topology and to estimate divergence times using a priori rates obtained for a related ground beetle genus. We found three main clades of late Eocene-early Oligocene origin: (1) the genus Doderotrechus and relatives; (2) the genus Trechus sensu lato, with most anisotopic subterranean genera, including the Pyrenean lineage and taxa from the Dinaric Alps; and (3) the genus Duvalius sensu lato, diversifying during the late Miocene and including all subterranean isotopic taxa. Most of the subterranean genera had an independent origin and were related to epigean taxa of the same geographical area, but there were three large monophyletic clades of exclusively subterranean species: the Pyrenean lineage, a lineage including subterranean taxa from the eastern Alps and the Dinarides, and the genus Anophthalmus from the northeastern Alps. Many lineages have developed similar phenotypes independently, showing extensive morphological convergence or parallelism., [Conclusions] The Alpine Trechini do not form a homogeneous fauna, in contrast with the Pyrenees, and show a complex scenario of multiple colonisations of the subterranean environment at different geological periods and through different processes. Examples go from populations of an epigean widespread species going underground with little morphological modifications to ancient, geographically widespread lineages of exclusively subterranean species likely to have diversified once fully adapted to the subterranean environment.

Nonadiabatic energy transfer from the translational motion (T) of a molecule impinging on metal surface to the metal's electrons may determine whether the molecule can lose enough energy to adsorb or react. Although it is thus relevant to heterogeneous catalysis, little is known about the strength of the coupling of T to electron hole pair (ehp) excitation. We present adiabatic ab initio molecular dynamics (AIMD) predictions of the scattering of 5 eV H-atoms from Cu and Au surfaces. Calculations of angularly resolved scattering reveal experimentally realizable conditions where only about 2% of the incidence energy is lost to the metal's phonons. Under these conditions, measurements of the translational energy loss should be able to determine the magnitude of any additional energy loss due to ehp excitation, information that is very valuable to the development of accurate theoretical descriptions of T→ehp coupling. © 2013 American Chemical Society.

The final product of galaxy evolution through cosmic time is the population of galaxies in the local universe. These galaxies are also those that can be studied in most detail, thus providing a stringent benchmark for our understanding of galaxy evolution. Through the huge success of spectroscopic single-fiber, statistical surveys of the Local Universe in the last decade, it has become clear, however, that an authoritative observational description of galaxies will involve measuring their spatially resolved properties over their full optical extent for a statistically significant sample. We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey, which has been designed to provide a first step in this direction. We summarize the survey goals and design, including sample selection and observational strategy. We also showcase the data taken during the first observing runs (June/July 2010) and outline the reduction pipeline, quality control schemes and general characteristics of the reduced data. This survey is obtaining spatially resolved spectroscopic information of a diameter selected sample of ∼600 galaxies in the Local Universe (0.005 < z < 0.03). CALIFA has been designed to allow the building of two-dimensional maps of the following quantities: (a) stellar populations: ages and metallicities; (b) ionized gas: distribution, excitation mechanism and chemical abundances; and (c) kinematic properties: both from stellar and ionized gas components. CALIFA uses the PPAK integral field unit (IFU), with a hexagonal field-of-view of ∼1.3 ′, with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 Å, using two overlapping setups (V500 and V1200), with different resolutions: R ∼ 850 and R ∼ 1650, respectively. CALIFA is a legacy survey, intended for the community. The reduced data will be released, once the quality has been guaranteed. The analyzed data fulfillthe expectations of the o

[EN] Prejanopterus curvirostra, from the Early Cretaceous of La Rioja province, was the first pterosaur genus and species described from Spain. The material comprises disarticulated cranial and postcranial remains from several individuals. The fossil-bearing bed is assigned to the lacustrine Leza Formation (eastern Cameros Basin, NW margin of the Iberian Range). This unit is regarded as either Berriasian-Valanginian or Barremian-Aptian. Prejanopterus curvirostris (specific name emended) was originally diagnosed on the basis of several characters of which the most significant was a lateral curvature of the rostrum. Re-examination of the holotype (rostrum) and paratype (partial rostrum with teeth) indicates that there is no genuine sideways bend of the preserved premaxilla-maxilla segments, but a slight dorsal curvature. Prejanopterus is characterized by a unique combination of characters: an emended diagnosis is provided. In contrast with previous estimates, the wing span of Prejanopterus was probably not much (if ever) in excess of 2 m. A phylogenetic analysis suggests that Prejanopterus is a basal pterodactyloid positioned between Pterodactylus and Cycnorhamphus-Gallodactylus. Prejanopterus represents the first evidence of Pterodactylidae in the Early Cretaceous of the Iberian Peninsula.

[EN] The mechanism of the fluoride anion recognition by an urea phthalimide chemosensor has been studied in detail by means of CASPT2//CASSCF calculations. Computational data are in well-agreement with changes in the photophysical properties previously reported experimentally in the presence or absence of fluoride anion. In both cases, fast relaxation from the S-2 potential energy surface leads to S-1 population. Deactivation of the excited state is in agreement with the experimental change in fluorescence observed when the anion is present. Mechanistic information obtained allows to provide an explanation of the experimental data and to suggest some modifications to improve the synthetic applicability of this type of chemosensors. (C) 2012 Elsevier Ltd. All rights reserved.

Autochthonous European insect diversity is the result of the very complex geological, geographic and climatic history of the Mediterranean area. The leaf beetle genus Cryptocephalus has over 250 species in this area. Among them stands out a group nearly endemic from this region consisting of conspicuous metallic green or blue beetles which can be found visiting yellow Asteraceae flowers in most mid- to high-altitude European grasslands: the Linnaean species C. hypochaeridis, C. sericeus, and all their relatives. In all, these are 32 species forming several taxonomically complex groups across Europe. We sampled all morphological diversity in this lineage and characterized it for two mitochondrial DNA genes. The mtDNA phylogeny of this assemblage was inferred, as well as the timing of its diversification using standard mtDNA substitution rates and a hypothetical Messinian vicariant split. The origin of the group can be traced back to western continental Eurasia in the Lower Miocene. Its subsequent taxonomic splits can be linked to specific periods in the formation of Europe, with a marked trend to east-west phylogenetic divides throughout time and space, and a nearly constant rate of diversification. Only during the Pleistocene, a significant increase in diversification rate can be associated with species formation in the C. hypochaeridis and C. sericeus species complexes. Within these latter groups, most taxa show some degree of mtDNA paraphyly as a result of their recent separation and remarkably by episodes of gene flow in areas of secondary contact among recently diverged species, possibly driven by climatic change. © 2011 The Authors. Zoologica Scripta © 2011 The Norwegian Academy of Science and Letters.

[ES] Un mundo con «fronteras abiertas», que no un «mundo sin fronteras», aporta el marco institucional más propicio para el respeto de los derechos humanos y la instauración de la justicia distributiva a nivel planetario. En este artículo se argumenta a favor de esta tesis. El horizonte propuesto se compara con el actual estado de cosas, caracterizado por la obstrucción sistemática de la libre circulación de personas. Ante este panorama, y con el fin de afrontar de manera más integral la cuestión de las migraciones internacionales, se señala la necesidad de adoptar una mirada cosmopolita. Mantener a la vista una opción situada más allá de lo realmente existente, que no de lo posible, resulta imprescindible para poder someter a una mirada crítica la inquietante perspectiva que nos presenta la movilidad humana como una potencial amenaza para el orden establecido.

Connections between (positive) mean ergodic operators acting in Banach lattices and properties of the underlying lattice itself are well understood (see the works of Emel'yanov, Wolff and Zaharopol). For Frechet lattices (or more general locally convex solid Riesz spaces) there is virtually no information available. For a Frechet lattice E, it is shown here that (amongst other things) every power-bounded linear operator on E is mean ergodic if and only if E is reflexive if and only if E. is Dedekind sigma-complete and every positive power-bounded operator on E is mean ergodic if and only if every positive power-bounded operator in the strong dual E'(beta) (no longer a Frechet lattice) is mean ergodic. An important technique is to develop criteria that detect when E admits a (positively) complemented lattice copy of c(0) l(1) or l(infinity). © Copyright © Royal Society of Edinburgh 2011.

In this paper we consider three variants of accepting networks of evolutionary processors. It is known that two of them are equivalent to Turing machines. We propose here a direct simulation of one device by the other. Each computational step in one model is simulated in a constant number of computational steps in the other one while a translation via Turing machines squares the time complexity. We also discuss the possibility of constructing simulations that preserve not only complexity, but also the shape of the simulated network. © 2011 Springer Science+Business Media B.V.

Could a laser field lead to the much sought-after tunable band gaps in graphene? By using Floquet theory combined with Green's functions techniques, we predict that a laser field in the mid-infrared range can produce observable band gaps in the electronic structure of graphene. Furthermore, we show how they can be tuned by using the laser polarization. Our results could serve as a guidance to design optoelectronic nanodevices.

An efficient order-N real-space Kubo approach is developed for the calculation of the thermal conductivity of complex disordered materials. The method, which is based on the Chebyshev polynomial expansion of the time evolution operator and the Lanczos tridiagonalization scheme, efficiently treats the propagation of phonon wave packets in real space and the phonon diffusion coefficients. The mean free paths and the thermal conductance can be determined from the diffusion coefficients. These quantities can be extracted simultaneously for all frequencies, which is another advantage in comparison with approaches based on the Green’s function. Additionally, multiple scattering phenomena can be followed through the time dependence of the diffusion coefficient deep into the diffusive regime, and the onset of weak or strong phonon localization could possibly be revealed at low temperatures for thermal insulators. The accuracy of our computational scheme is demonstrated by comparing the calculated phonon mean free paths in isotope-disordered carbon nanotubes with Landauer simulations and analytical results. Then the upscalability of the method is illustrated by exploring the phonon mean free paths and the thermal conductance features of edge-disordered graphene nanoribbons having widths of ~20 nm and lengths as long as a micrometer, which are beyond the reach of other numerical techniques. It is shown that the phonon mean free paths of armchair nanoribbons are smaller than those of zigzag nanoribbons for the frequency range which dominates the thermal conductance at low temperatures. This computational strategy is applicable to higher-dimensional systems as well as to a wide range of materials.

The electrical response of graphene-based materials can be tailored under mechanical stress. We report different switching behaviors that take place in mechanically deformed graphene nanoribbons prior to the breakage of the junction. By performing tight-binding molecular dynamics, the study of structural changes of graphene nanoribbons with different widths is achieved, revealing that carbon chains are the ultimate bridges before the junction breaks. The electronic and transport calculations show that binary on/off states can be switched prior to and during breakage depending on the atomic details of the nanoribbon. This work supports the interpretation of recent experiments on nonvolatile memory element engineering based on graphene break junctions.

We report a theoretical study suggesting a novel type of electronic switching effect, driven by the geometrical reconstruction of nanoscale graphene-based junctions. We considered junction structures that have alternative metastable configurations transformed by rotations of local carbon dimers. The use of external mechanical strain allows a control of the energy-barrier heights of the potential profiles and also changes the reaction character from endothermic to exothermic or vice versa. The reshaping of the atomic details of the junction encode binary electronic “on” or “off” states, with on/off transmission ratio that can reach up to 104–105. Our results suggest the possibility to design modern logical switching devices or mechanophore sensors, monitored by mechanical strain and structural rearrangements.

[EN] Five species of the genus Siagona Latreille 1804 (Carabidae: Siagoninae) are known from Morocco. Siagona taggadertensis n. sp., a remarkable species of Carabidae from a Moroccan cave is described. This insect is spectacular by its large size (one of the largest species of the genus), its external morphology, which isolates it from all the north african representant of the genus, and for the conditions of its discovery: its only known from the remains of six specimens, all of them found in the cave of Taggadert, western Atlas. Hypotheses concerning the ecology of this species are discussed., [FR] Le genre Siagona Latreille 1804 (Carabidae: Siagoninae), compte 5 espèces au Maroc. Siagona taggadertensis n. sp., remarquable espèce collectée dans une grotte marocaine est décrite. Cet insecte est spectaculaire tant par sa grande taille, sa morphologie externe qui l’isole au premier coup d’oeil des représentants nord africains du genre Siagona, que par les conditions de sa découverte : aucun des spécimens n’ont été collectés en dehors de la grotte de Taggadert, Atlas occidental. Des hypothèses concernant l’écologie de cette espèce sont fournies.

Carabid beetles of tribe Trechini (Coleoptera) are one of the main groups of insects that colonized the subterranean environment. Many species of this group have developed similar morphological modifications related to the subterranean life, resulting in a characteristic Aphaenops-like phenotype that obscures their phylogenetic relationships (depigmented, blind, elongated body and appendages, narrow head and pronotum). We present here the result of a molecular study using a combination of nuclear (small ribosomal unit, large ribosomal unit) and mitochondrial (cox1, cyb, rrnL, trnL, nad1) genes to investigate the phylogenetic placement of the highly modified subterranean genera of the tribe Trechini from the west Mediterranean area (France, Spain, Morocco and Sardinia). Our results confirm the multiple independent origin of troglomorphism among these genera, and reveal a pattern largely determined by geographical proximity. We discuss the validity of some groups proposed on the base of morphological features, and provide estimates of divergence between subterranean genera and other groups of Trechini, including epigean species of the same area. We compare the estimated age for the origin of the main groups resulting from two different calibrations, using one the standard mitochondrial mutation rate (2.3% divergence per Myr) and the other the separation between Sardinia and mainland 33 Ma. Under the first scenario, the main groups of genera would have a late Miocene origin, with a subsequent colonization of north Africa at the Pliocene–Pleistocene boundary. The assumption that the main groups originated through vicariance due to the separation of the Sardinian plate in the Oligocene results in a Messinian origin of the north African subterranean taxa, and a global mitochondrial rate reduced to 1% divergence per Myr.

From the 1980 Maitatsine uprising to the 2009 Boko Haram uprising, Nigeria was bedevilled by ethno-religious conflicts with devastating human and material losses. But the Boko Haram uprising of July 2009 was significant in that it not only set a precedent, but also reinforced the attempts by Islamic conservative elements at imposing a variant of Islamic religious ideology on a secular state. Whereas the religious sensitivity of Nigerians provided fertile ground for the breeding of the Boko Haram sect, the sect’s blossoming was also aided by the prevailing economic dislocation in Nigerian society, the advent of party politics (and the associated desperation of politicians for political power), and the ambivalence of some vocal Islamic leaders, who, though they did not actively embark on insurrection, either did nothing to stop it from fomenting, or only feebly condemned it. These internal factors coupled with growing Islamic fundamentalism around the world make a highly volatile Nigerian society prone to violence, as evidenced by the Boko Haram uprising. Given the approach of the Nigerian state to religious conflict, this violence may remain a recurring problem. This paper documents and analyses the Boko Haram uprising, as well as its links with the promotion of Islamic revivalism and the challenges it poses to the secularity of the Nigerian state., Vom Maitatsine-Aufstand 1980 bis zu den Boko-Haram-Unruhen 2009 hat die nigerianische Bevölkerung unter den verheerenden menschlichen und materiellen Kosten ethnisch-religiöser Konflikte gelitten. Die Boko-Haram-Unruhen (Juli 2009) markierten allerdings eine qualitative Veränderung, denn sie stellten einen Präzedenzfall dar und verstärkten Versuche konservativer Anhänger des Islam, im säkularen nigerianischen Staat Elemente islamischer Ideologie einzuführen. Angesichts der Empfänglichkeit der Nigerianer für religiöses Denken konnte sich die Boko-Haram-Sekte schnell ausbreiten, erleichtert durch die nach wie vor bestehende ökonomische Polarisierung der nigerianischen Gesellschaft, die erneut heftig aufgebrochene Konkurrenz der Parteien um die politische Macht und die Ambivalenz einiger lautstarker islamischer Führer, die zwar nicht explizit zum Aufstand aufriefen, aber auch nichts zur Beendigung der Hetze beitrugen und diese nur vorsichtig verurteilten. Diese internen Faktoren und der gleichzeitige weltweite Aufschwung des islamischen Fundamentalismus führten in der hoch volatilen nigerianischen Gesellschaft zu den gewaltsam ausgetragenen Boko-Haram-Unruhen. Die im nigerianischen Staat strukturell angelegte Gefahr religiöser Auseinandersetzungen legt nahe, dass solche Gewaltausbrüche ein immer wiederkehrendes Problem bleiben könnten. Der vorliegende Beitrag dokumentiert und analysiert die Boko-Haram-Unruhen und skizziert ihre Bedeutung für die Wiederbelebung des politischen Islam und die damit verbundenen Herausforderungen für den säkularen nigerianischen Staat.

The optical properties of multi-layer InAs/InP quantum wires (QWRs) with two different spacer thicknesses have been investigated by means of room temperature surface photovoltage (SPV) and photoluminescence (PL) spectroscopies, combined with empirical tight binding electronic structure calculations and structural data. The SPV and PL spectra reveal several features, which energy positions are in good agreement. They have been ascribed to excitonic transitions, which take place in the QWR families with heights differing by an integer number of monolayers. Comparing the experimental results with the theoretical ones, we have estimated the QWR family heights and the average atomic concentration of phosphorus in the QWRs. From the simultaneous analysis of the SPV amplitude and phase spectra, based on our vector model for SPV signal representation, a deeper understanding of the SPV results and of the mechanisms of carrier separation in the sample is obtained.

Enantioselective organocatalytic asymmetric Diels-Alder­ reactions provide a facile and efficient route to optically active functionalized cyclohexenes, which can be further transformed into a variety of important organic compounds. A variety of small organic molecules such as prolines, imidazolidinones, chiral Brønsted­ acids, guanidines, carbenes and Cinchona alkaloids can be used as different catalyst systems to induce enantioselectivity in the reaction. This review provides an overview of the history of the asymmetric organocatalyzed Diels-Alder reaction.

This review covers the most recent applications of organocatalysis in the synthesis of natural products and non-natural biologically active molecules. Our aim is to showcase how organocatalytic reactions have overcome some of their teething problems and how they frequently offer very practical solutions to long-standing synthetic challenges. 161 references are cited.

We report on a theoretical study of charge transport properties of graphene nanoribbons under external mechanical stress. The influence of mechanical forces on the ribbon conductance is shown to be strongly dependent on the ribbon edge symmetry, i.e., zigzag versus armchair. In contrast to zigzag-edge nanoribbons which remain robust against high strain deformations, a stretching-induced metal-semiconductor transition is obtained for armchair-edge configurations. Our results point out that armchair edge ribbons are consequently much better suited for electromechanical applications.

We have developed an efficient order-N real-space Kubo approach for the calculation of the phonon conductivity which outperforms state-of-the-art alternative implementations based on the Green’s function formalism. The method treats efficiently the time-dependent propagation of phonon wave packets in real space, and this dynamics is related to the calculation of the thermal conductance. Without loss of generality, we validate the accuracy of the method by comparing the calculated phonon mean free paths in disordered carbon nanotubes (isotope impurities) with other approaches, and further illustrate its upscalability by exploring the thermal conductance features in large width edge-disordered graphene nanoribbons (up to ∼20 nm), which is out of the reach of more conventional techniques. We show that edge disorder is the most important scattering mechanism for phonons in graphene nanoribbons with realistic sizes and thermal conductance can be reduced by a factor of ∼10.

Estudio introductorio a la obra de Heinrich Heine La escuela romántica, edición a cargo de Juan Carlos Velasco. Este volumen, dotado de un amplio aparato crítico de notas, se completa con una serie de textos de Heine, seleccionados por el editor, que iluminan la evolución del pensamiento de Heine acerca del movimiento romántico alemán.

The optical properties of InAs/InP multi-layer quantum wire (QWR) structures of various spacer thicknesses have been investigated by means of room temperature surface photovoltage and photoluminescence spectroscopy. Combined with empirical tight binding calculations, the spectra have revealed transitions assigned to QWR families with heights equal to integer number of 5, 6 and 7 monolayers. From the comparison of the experimental and theoretical results the atomic concentration of phosphorus in the wires has been estimated.

info:eu-repo/semantics/nonPublished

[ES]: Las reacciones catalíticas enantioselectivas han tenido un impacto muy significativo en el desarrollo de la química orgánica sintética en los últimos 30 años. Entre éstas, los métodos basados exclusivamente en la catálisis en ausencia de metal (organocatálisis) han llegado a alcanzar una gran importancia, convirtiéndose en herramientas muy útiles para la construcción de estructuras moleculares complejas. En los últimos años hemos podido asistir a un espectacular avance de estos nuevos métodos organocatalíticos, algunos de los cuales se describen en este trabajo., [EN]: Catalytic enantioselective reactions have had a significant impact on the development of synthetic organic chemistry during the last 30 years. Among them, methods based exclusively on metal-free organic catalysts (organocatalysis) have achieved a great importance and they are becoming powerful tools in the construction of complex molecular skeletons. Therefore, the last few years have witnessed a spectacular advance in new organocatalytic methods, some of them are described in this review.

The intramolecular Rauhut−Currier reaction creates a carbon−carbon bond between two tethered Michael acceptors. Previous asymmetric versions have relied on 1,4-additions of chiral nucleophilic catalysts. Herein, we investigate a novel strategy that involves the formation of electron rich dienamines as key intermediates. Our methodology provides an efficient entry to the iridoid framework.

Asymmetric aza-Henry reactions provide excellent routes for the synthesis of optically active organic compounds bearing two vicinal different nitrogenated functionalities that can be further transformed into a variety of interesting compounds such as 1, 2-diamines or a-amino acids. The catalytic asymmetric version of the reaction (also called the nitro-Mannich reaction) provides highly efficient access to enantiomerically pure compounds. Both metal-based and organic catalysts can be used to promote these reactions in a enantioselective way; in particular, a great variety of different organocatalysts- including thioureas, N-oxides, quaternary ammonium salts and chiral Brensted acids - have demonstrated their efficiency, as has recently been reported by several research groups. In addition, considerable effort is being made in controlling the syn/anti diastereoselectivities of these reactions when substituted nitroalkanes are used as substrates. In this microreview recent advances, including scope and limitations, are discussed and applications of different catalytic systems for catalytic asymmetric aza-Henry reactions are presented. © Wiley-VCH Verlag GmbH & Co. KGaA.

We performed high-pressure ADXRD studies on Fe5Si3 and Ni2Si up to 75 GPa. No evidence of the occurrence of a phase transition was observed in them. Fe5Si3 was found to compress isotropically, but an anisotropic compression was observed in Ni2Si. These results are supported by ab initio total-energy calculations, which for Fe5Si3 also predicted a transition at 283 GPa from the hexagonal P63/mcm phase to a cubic phase. High-pressure melting studies were conducted on FeSi up to 70 GPa. We found a change in the melting slope at 12 GPa, which is attributed to the intersection of the melting curve with the phase boundary between epsilon-FeSi and CsCl-type FeSi. Finally, an equation of state for Fe5Si3 and Ni2Si is reported.

The nanostructural changes associated to the multiple melting behaviour of isotropic cold-crystallized poly(ethylene terephthalate) (PET) have been investigated by means of simultaneous wide- and small-angle X-ray scattering, using a synchrotron radiation source. Variations in the degree of crystallinity, coherent lateral crystal size and long period values, as a function of temperature, for two different heating rates are reported for cold-crystallized samples in the 100-190 °C range. The Interface Distribution Function analysis is also employed to provide the crystalline and amorphous layer thickness values at various temperatures of interest. Results suggest that samples crystallized at both low (Ta = 100-120 °C) and high (Ta = 160-190 °C) temperatures are subjected to a nearly continuous nanostructural reorganization process upon heating, starting immediately above Tg (≈80 °C) and giving rise to complete melting at ≈260 °C. For all the Ta investigated, a melting-recrystallization mechanism seems to take place once Ta is exceeded, concurrently to the low-temperature endotherm observed in the DSC scans. For low-Ta and slow heating rates (2 °C/min), a conspicuous recrystallization process is predominant within Ta + 30 °C ≤ T ≤ 200 °C. In contrast, for high-Ta, an increasingly strong melting process is observed. For both, high- and low-Ta, an extensive structural reorganization takes place above 200 °C, involving the appearance of new lamellar stacks simultaneously to the final melting process. The two mechanisms should contribute to the high-temperature endotherm in the DSC scan. Finally, the use of a high heating rate is found to hinder the material's overall recrystallization process during the heating run and suggests that the high-temperature endotherm is ascribed to the melting of lamellae generated or thickened during the heating run. © 2008 Elsevier Ltd. All rights reserved.

We performed high-pressure angle dispersive x-ray diffraction measurements on Fe5 Si3 and Ni2 Si up to 75 GPa. Both materials were synthesized in bulk quantities via a solid-state reaction. In the pressure range covered by the experiments, no evidence of the occurrence of phase transitions was observed. On top of that, Fe5 Si3 was found to compress isotropically, whereas an anisotropic compression was observed in Ni2 Si. The linear incompressibility of Ni2 Si along the c axis is similar in magnitude to the linear incompressibility of diamond. This fact is related to the higher valence-electron charge density of Ni2 Si along the c axis. The observed anisotropic compression of Ni2 Si is also related to the layered structure of Ni2 Si, where hexagonal layers of Ni2+ cations alternate with graphite-like layers formed by (NiSi)2- entities. The experimental results are supported by ab initio total-energy calculations carried out using density functional theory and the pseudopotential method. For Fe5 Si3, the calculations also predicted a phase transition at 283 GPa from the hexagonal P 63/mcm phase to the cubic structure adopted by Fe and Si in the garnet Fe5 Si3 O12. The room-temperature equations of state for Fe5 Si3 and Ni2 Si are also reported and a possible correlation between the bulk modulus of iron silicides and the coordination number of their minority element is discussed. Finally, we report additional descriptions of these structures, in particular, of the predicted high-pressure phase of Fe5 Si3 (the cation subarray in the garnet Fe5 Si3 O12), which can be derived from spinel Fe2 Si O4 (Fe6 Si3 O12). © 2008 The American Physical Society.

'In situ' wide angle (WAXS) and small angle X-ray scattering (SAXS) studies were carried out to characterize the structural changes occurring during the conversion of a polyamic acid into the polyimide in the presence of fullerene, C60. The variations in crystallinity, long period, and the SAXS invariant of the samples are discussed in the light of the various temperature ranges studied. The conversion of the polyamic acid into the polyimide is analyzed according to the different structural steps. Results reveal that C60 affects the degree of order of the composite in the molecular direction, giving rise to slightly smaller crystals than those found in pure polyamic acid. The difference in the SAXS data between the pure PAA and the composite are discussed through the interaction of C60 molecules with the polyamic acid, which seems to hinder the imidization reaction up to 185°C. © 2007 VSP.

Comprehensive knowledge of the dynamic behaviour of electrons in condensed-matter systems is pertinent to the development of many modern technologies, such as semiconductor and molecular electronics, optoelectronics, information processing and photovoltaics. Yet it remains challenging to probe electronic processes, many of which take place in the attosecond (1 as = 10-18 s) regime. In contrast, atomic motion occurs on the femtosecond (1 fs = 10-15 s) timescale and has been mapped in solids in real time1,2 using femtosecond X-ray sources3. Here we extend the attosecond techniques4,5 previously used to study isolated atoms in the gas phase to observe electron motion in condensed-matter systems and on surfaces in real time. We demonstrate our ability to obtain direct time-domain access to charge dynamics with attosecond resolution by probing photoelectron emission from single-crystal tungsten. Our data reveal a delay of approximately 100 attoseconds between the emission of photoelectrons that originate from localized core states of the metal, and those that are freed from delocalized conduction-band states. These results illustrate that attosecond metrology constitutes a powerful tool for exploring not only gas-phase systems, but also fundamental electronic processes occurring on the attosecond timescale in condensed-matter systems and on surfaces.

[EN] After drawing up the contraposition between the liberal doctrine and the democratic theory, which pervades all modern and contemporary political philosophy, this article examines the reasons that Habermas states for considering that the effective usufruct of human rights is strictly linked with the exercise of a democracy conceived as deliberative practice, so that the delineated contraposition could be resolved. The exposition advances in four steps: first, the theoretical features of the discoursive meaning of human rights are analysed; then, the content of the legal framework considered by Habermas is dissected; in a next step, the reasons for the mutual relation between the principle of popular sovereignty and human rights are identified; finally, the model of deliberative politics is presented as an adequate way to include both factors of legitimation simultaneuously., [ES] Tras plantear la contraposición entre la doctrina liberal y la teoría democrática que atraviesa coda la filosofía política moderna y contemporánea, en este anículo se examinan los motivos que arguye Habermas para considerar que el disfrute efectivo de los derechos humanos se encuentra estrechamente conectado con el ejercicio de la democracia concebida como práctica deliberativa, de modo que la contraposición señalada podría ser salvada. La exposición se hace en cuatro pasos: en primer lugar, se analizan los rasgos teóricos de la noción discursiva de los derechos humanos; posteriormente se disecciona el contenido del sistema de los derechos contemplados por Habermas; luego se ofrecen las razones por las que el principio de la soberanía popular y los derechos humanos se remiten mutuamentej y, finalmente, se presenta el modelo de política deliberativa como una vía adecuada para poner en juego simultáneamente ambos factores de legitimación.

[EN] Pyrylium-containing mesoporous materials have been used for the chromo-fluorogenic sensing of biogenic amines in an aqueous environment.

Ustilago maydis is a ubiquitous pathogen of maize and a well-established model organism for the study of plant-microbe interactions. This basidiomycete fungus does not use aggressive virulence strategies to kill its host. U. maydis belongs to the group of biotrophic parasites (the smuts) that depend on living tissue for proliferation and development. Here we report the genome sequence for a member of this economically important group of biotrophic fungi. The 20.5-million-base U. maydis genome assembly contains 6,902 predicted protein-encoding genes and lacks pathogenicity signatures found in the genomes of aggressive pathogenic fungi, for example a battery of cell-wall-degrading enzymes. However, we detected unexpected genomic features responsible for the pathogenicity of this organism. Specifically, we found 12 clusters of genes encoding small secreted proteins with unknown function. A significant fraction of these genes exists in small gene families. Expression analysis showed that most of the genes contained in these clusters are regulated together and induced in infected tissue. Deletion of individual clusters altered the virulence of U. maydis in five cases, ranging from a complete lack of symptoms to hypervirulence. Despite years of research into the mechanism of pathogenicity in U. maydis, no 'true' virulence factors had been previously identified. Thus, the discovery of the secreted protein gene clusters and the functional demonstration of their decisive role in the infection process illuminate previously unknown mechanisms of pathogenicity operating in biotrophic fungi. Genomic analysis is, similarly, likely to open up new avenues for the discovery of virulence determinants in other pathogens. ©2006 Nature Publishing Group.