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Prochlorococcus and Synechococcus are the two most abundant photosynthetic organisms on Earth, with a strong influence on the biogeochemical carbon and nitrogen cycles. Early reports demonstrated the streamlining of regulatory mechanisms in nitrogen metabolism and the removal of genes not strictly essential. The availability of a large series of genomes, and the utilization of latest generation molecular techniques have allowed elucidating the main mechanisms developed by marine picocyanobacteria to adapt to the environments where they thrive, with a particular interest in the strains inhabiting oligotrophic oceans. Given that nitrogen is often limited in those environments, a series of studies have explored the strategies utilized by Prochlorococcus and Synechococcus to exploit the low concentrations of nitrogen-containing molecules available in large areas of the oceans. These strategies include the reduction in the GC and the cellular protein contents; the utilization of truncated proteins; a reduced average amount of N in the proteome; the development of metabolic mechanisms to perceive and utilize nanomolar nitrate concentrations; and the reduced responsiveness of key molecular regulatory systems such as NtcA to 2-oxoglutarate. These findings are in sharp contrast with the large body of knowledge obtained in freshwater cyanobacteria. We will outline the main discoveries, stressing their relevance to the ecological success of these important microorganisms.

Parkinson’s disease (PD) is a chronic and progressive movement disorder affecting the nervous system of patients. PD alters the capacity to sustain a steady rhythm in the gait leading to impaired motor skills. The diagnosis of PD is a complex task that encompasses motor and non-motor symptoms. More than 50% of patients suffer from freezing in their legs during walking, generally defined as Freezing of Gait (FOG). Hence, gait evaluation is essential for physicians to detect the disease and track its severity. In this context, intelligent learning algorithms have been recently used to facilitate the diagnostic process. However, an accurate diagnosis is still required. This paper presents an effective and novel approach to diagnose PD using gait analysis, wearable sensors, and deep learning techniques. To achieve this goal, an Artificial Neural Network multiclassifier system (ANN) has been developed. The proposed model predicts the severity of PD by detecting the stage of the disease. It uses a further analysis of movement alteration, supervised learning, and clinical assessment based on Hoehn & Yahr (H&Y) scores. The experimental results indicate a high efficiency of the proposed method in tracking PD severity. The method can make a distinction between idiopathic PD patients and healthy individuals, and classify them in the levels 0, 2, 2.5 and 3 according to the symptoms progress and level of disability. The model achieves an outstanding performance with an accuracy of 97%. Thus, this study emphasizes the use of a prediction learning algorithm that can be helpful and valuable for clinical examinations.

The persistence of ferroelectricity in ultrathin layers relies critically on screening or compensation of polarization charges which otherwise destabilize the ferroelectric state. At surfaces, charged defects play a crucial role in the screening mechanism triggering novel mixed electrochemical-ferroelectric states. At interfaces, however, the coupling between ferroelectric and electrochemical states has remained unexplored. Here, we make use of the dynamic formation of the oxygen vacancy profile in the nanometer-thick barrier of a ferroelectric tunnel junction to demonstrate the interplay between electrochemical and ferroelectric degrees of freedom at an oxide interface. We fabricate ferroelectric tunnel junctions with a ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ bottom electrode and ${\mathrm{BaTiO}}_{3}$ ferroelectric barrier. We use poling strategies to promote the generation and transport of oxygen vacancies at the metallic top electrode. Generated oxygen vacancies control the stability of the ferroelectric polarization and modify its coercive fields. The ferroelectric polarization, in turn, controls the ionization of oxygen vacancies well above the limits of thermodynamic equilibrium, triggering the build up of a Schottky barrier at the interface which can be turned on and off with ferroelectric switching. This interplay between electronic and electrochemical degrees of freedom yields very large values of the electroresistance (more than ${10}^{6}%$ at low temperatures) and enables a controlled switching between clockwise and counterclockwise switching modes in the same junction (and consequently, a change of the sign of the electroresistance). The strong coupling found between electrochemical and electronic degrees of freedom sheds light on the growing debate between resistive and ferroelectric switching in ferroelectric tunnel junctions, and moreover, can be the source of novel concepts in memory devices and neuromorphic computing.

This paper introduces a novel geometric framework to define and study hybrid systems. We exploit the geometry and topology of the set of jump points, where the instantaneous change of dynamics takes place, in order to gain controllability for the system. This approach allows us to describe new global controllability tests for hybrid control systems. We illustrate these results with several examples where none of the continuous control systems are controllable, but the associated hybrid system is controllable because of the characteristics of the jump set., The authors have been partially supported by Ministerio de Economía y Competitividad (MINECO, Spain) under grant MTM 2015-64166-C2-2P. MBL and DMdD acknowledge financial support from the Spanish Ministerio de Economía y Competitividad, through the research grants PID2019-106715GB-C21, MTM2016-76702-P, I-Link Project (Ref: linkA20079) from CSIC and “Severo Ochoa Programme for Centers of Excellence” in R&D (SEV-2015-0554). MBL has been financially supported by “Programa propio de I+D+I de la Universidad Politécnica de Madrid: Ayudas dirigidas a jóvenes investigadores doctores para fortalecer sus planes de investigación”. JC has been financially supported by NSF Award NSF ECCS-1917177. SM has been financially supported by AFOSR Award FA9550-18-1-0158. MCML acknowledges the financial support from the Spanish Ministerio de Economía y Competitividad project MTM2014-54855-P, the Spanish Ministerio de Ciencia Innovación y Universidades project PGC2018-098265-B-C33 and from the Secretary of University and Research of the Ministry of Business and Knowledge of the Catalan Government project 2017-SGR-932.

Magnetoelectric coupling in artificial multiferroic interfaces can be drastically affected by the switching of oxygen vacancies and by the inversion of the ferroelectric polarization. Disentangling both effects is of major importance toward exploiting these effects in practical spintronic or spinorbitronic devices. We report on the independent control of ferroelectric and oxygen vacancy switching in multiferroic tunnel junctions with a La_(0.7)Sr_(0.3)MnO_3 bottom electrode, a BaTiO_3 ferroelectric barrier, and a Ni top electrode. We show that the concurrence of interface oxidation and ferroelectric switching allows for the controlled inversion of the interface spin polarization. Moreover, we show the possibility of a spin-memristor where the controlled oxidation of the interface allows for a continuum of memresistance states in the tunneling magnetoresistance. These results signal interesting new avenues toward neuromorphic devices where, as in practical neurons, the electronic response is controlled by electrochemical degrees of freedom.

A middle-aged man with cardiovascular risk factors, who suffered from a slight loss of unilateral vision for 6 months. After obtaining a diagnosis of diffuse choroiditis+papillitis within a probable masquerade syndrome, the patient was referred to outpatient Internal Medicine where this diagnosis was confirmed as an extended neoplastic disease.

El relleno sedimentario que alberga el registro arqueológico y antropológico de la Galería del Osario (cueva de El Sidrón) presenta una alta complejidad, tanto en los tipos de sedimentos como en su distribución espacial en la cavidad. Los principales factores que rigen esta complejidad son la naturaleza episódica y altamente energética de gran parte de las unidades litoestratigráficas reconocidas y la irregular geometría del propio conducto, que compartimenta significativamente las áreas de deposición. A modo de resumen puede indicarse que en la Galería del Osario quedan representados todos los tipos de materiales detríticos típicos de depósitos alóctonos en ambiente kárstico; desde materiales bien seleccionados de granulometría fina representativos de facies de encharcamiento (arcillas de la unidad O) o de desbordamiento (Unidad IV), a depósitos groseros mal seleccionados correspondientes a coladas de barro y detritos en masa (Unidad II y base de unidad III), pasando por típicas facies fluvio-kársticas o de canal compuestas por materiales arenosos con laminaciones y estructuras de flujo (unidades I y II). Los restos óseos se concentran en la unidad III. El área fuente se sitúa en cotas superiores a la Galería del Osario, es decir, en los niveles intermedio o superior del sistema kárstico, y el depósito o entrada de material óseo a la Galería del Osario se activaría en episodios de alta energía relacionado con eventos de inundación y/o tormenta. The sedimentary infill bearing the archaeological and anthropological record of the Ossuary Gallery (the Sidrón cave) shows high complexity in both sediment types and their spatial distribution in the cavity. The main factors that govern this complexity are the episodic and highly energetic nature of the recorded sedimentary infill units and the irregular geometry of the gallery itself, which significantly compartmentalized areas of deposition. Briefly, all types of typical allochthonous detrital material deposits in karst environments are represented in the Ossuary Gallery; from well-sorted fine-grained sediment facies representative of backswamp (clays of the unit O) or slackwater (Unit IV), to poorly-sorted coarse-grained deposits corresponding to mudflows and debris flows (Unit II and Unit III base), and typical channel facies composed of laminated sands and silts (units I and II). The bone and lithic remains are concentrated in unit III. The source area is above the Ossuary Gallery, at the intermediate or higher karst levels. The input of archeological material to the Ossuary Gallery was triggered in high energy episodes in association to flood events and / or storms. Este trabajo se ha financiado desde 1999 mediante diferentes contratos de investigación realizados entre el Gobierno del Principado de Asturias, la Universidad de Oviedo, la Universidad de Alicante, el Museo Nacional de Ciencias Naturales (CSIC, Madrid) y la Universidad de Salamanca.

Summary What is known and Objective Medication is the main treatment option for patients with chronic atrial fibrillation. However, medication can have negative effects. We aimed to detect negative outcomes associated with medication that led to patients with chronic atrial fibrillation presenting themselves to hospital emergency departments. We assessed the severity of those outcomes and comment on whether they could have been avoided. Methods This descriptive, cross-sectional study included all patients with chronic atrial fibrillation who attended the emergency department of our tertiary hospital. We used the Dader method to identify and evaluate the negative outcomes associated with medication through interviews with patients and scrutiny of the clinical charts. Results and Discussion Of the 198 eligible patients who presented at the emergency department, 134 (67·7%) did so because of negative outcomes associated with medication (41% related to necessity, 32·1% to effectiveness and 26·9% to safety); 67·9% of those negative outcomes could have been avoided. In terms of severity, 6·7% were mild, 31·3% moderate, 51·5% severe and 10·4% fatal. The Anatomical Therapeutic Chemical Classification anatomical group most frequently associated with negative outcomes was the cardiovascular system, followed by blood/blood-forming organs. What is new and Conclusion A high percentage of patients with chronic atrial fibrillation presenting at hospital emergency departments had negative outcomes associated with medication. Some led to deaths. More than half of these were severe, and most could have been avoided.

To identify pretransplant predictors of early mortality (90 days after transplantation) and evaluate their discriminating capacity in adult liver transplant recipients (LTR).An observational, retrospective, nested cases-controls study from a consecutive cohort of LTRs was carried out.University hospital.All consecutive LTR between January 2003 and December 2016 were eligible for inclusion. Patients with acute liver failure, previous graft dysfunction, simultaneous multiple organ transplantation, non-heart beating donors, and those needing urgent retransplantation during the study period were excluded. The analysis comprised 471 patients.Pretransplant characteristics were the main variables of interest. The LTR were grouped according to the dependent variable (early mortality). Multivariate logistic regression analysis was conducted to identify predictors of early mortality. The discriminating capacity of the models obtained was evaluated by comparing ROC curves (models versus MELD-Na).The MELD-Na score (OR = 1.069, 95% CI = 1.014-1.127), age60 years (OR = 2.479, 95% CI = 1.226-5.015), and LTR height163cm (OR = 4.092, 95% CI = 2.115-7.917) were identified as independent predictors of early mortality. The cause of transplantation (hepatocellular carcinoma or decompensated cirrhosis) was identified as a confounding factor.In LTR due to decompensated cirrhosis, the MELD-Na score, age60 years, and height163cm are independent predictors of early mortality. These factors provide a better classification model than the MELD-Na score for early post-transplant mortality.

We investigate the effects of strain on the topological order of the ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ family of topological insulators by ab initio first-principles methods. Strain can induce a topological phase transition and we present the phase diagram for the 3D topological insulators, ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$, ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}$, ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, and ${\mathrm{Sb}}_{2}{\mathrm{Se}}_{3}$, under combined uniaxial and biaxial strain. Their phase diagram is universal and shows metallic and insulating phases, both topologically trivial and nontrivial. In particular, uniaxial tension can drive the four compounds into a topologically trivial insulating phase. We propose a ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}/{\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ heterojunction in which a strain-induced topological interface state arises in the common gap of this normal insulator--topological insulator heterojunction. Unexpectedly, the interface state is confined in the topologically trivial subsystem and is physically protected from ambient impurities. It can be switched on or off by means of uniaxial strain and therefore ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}/{\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ heterojunctions provide a topological system which hosts tunable robust helical interface states with promising spintronic applications.

Undoped iron superconductors accommodate n=6 electrons in five d orbitals. Experimental and theoretical evidence shows that the strength of correlations increases with hole doping, as the electronic filling approaches half filling with n=5 electrons. This evidence delineates a scenario in which the parent compound of iron superconductors is the half-filled system, in analogy to cuprate superconductors. In cuprates the superconductivity can be induced upon electron or hole doping. In this work we propose to search for high-Tc superconductivity and strong correlations in chromium pnictides and chalcogenides with n, Funding from Ministerio de Economía, Industria y Competitividad (Spain) via Grants No. FIS2012-33521, No. FIS2014-53218-P, No. FIS2015-64654-P, and No. MAT2015-66888-C3-1-R and from Fundación Ramón Areces is gratefully acknowledged. J.L. acknowledges the financial support of the National Natural Science Foundation of China (Grants No. 11374186 and No. 51231007) and the China Scholarship Council.

The peculiar features of domain walls observed in ferroelectrics make them promising active elements for next-generation non-volatile memories, logic gates and energy-harvesting devices. Although extensive research activity has been devoted recently to making full use of this technological potential, concrete realizations of working nanodevices exploiting these functional properties are yet to be demonstrated. Here, we fabricate a multiferroic tunnel junction based on ferromagnetic LaSrMnO electrodes separated by an ultrathin ferroelectric BaTiO tunnel barrier, where a head-to-head domain wall is constrained. An electron gas stabilized by oxygen vacancies is confined within the domain wall, displaying discrete quantum-well energy levels. These states assist resonant electron tunnelling processes across the barrier, leading to strong quantum oscillations of the electrical conductance., Work supported by Spanish MINECO through grants MAT2014-52405-C02-01 and MAT2014-52405-C02-02, MAT2015-066888-C3-1-R, MAT2015-066888-C3-3-R (MINECO/FEDER) and CAM S2013/MIT-2740. Research at ORNL sponsored by the US Department of Energy (DOE), Basic Energy Sciences (BES), M.V. acknowledges support from Fundación BBVA. G.S. and M.C. acknowledge support from ERC Starting Investigator Grant #239739 STEMOX. J.I.B. acknowledges the Spanish Supercomputing Network (RES) and CeSViMa (project FI-2016-2-0006). J.S. thanks Université Paris Saclay (DÁlembert Program) and CNRS for financing his stay at CNRS Thales.

Dense (>98 th%) and homogeneous ceramic/metal composites were obtained by spark plasma sintering (SPS) using ZrO and lamellar metallic powders of tantalum or niobium (20 vol.%) as starting materials. The present study has demonstrated the unique and unpredicted simultaneous enhancement in toughness and strength with very high flaw tolerance of zirconia/Ta composites. In addition to their excellent static mechanical properties, these composites also have exceptional resistance to fatigue loading. It has been shown that the major contributions to toughening are the resulting crack bridging and plastic deformation of the metallic particles, together with crack deflection and interfacial debonding, which is compatible with the coexistence in the composite of both, strong and weak ceramic/metal interfaces, in agreement with predictions of ab-initio calculations. Therefore, these materials are promising candidates for designing damage tolerance components for aerospace industry, cutting and drilling tools, biomedical implants, among many others., This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) under the project MAT2015-66888-C3-1-R.

The micromagnetic exchange stiffness is a critical parameter in numerical modeling of magnetization dynamics and reversal processes, yet the current literature reports a wide range of values even for such simple and widely used material as cobalt. Using the ab initio estimated Heisenberg parameters we calculate the low temperature micromagnetic exchange stiffness for hexagonal-close-packed (hcp) and face-centered-cubic cobalt. For hcp Co they are slightly different in the directions parallel and perpendicular to the $c$ axis. We establish the exchange stiffness scaling relation with magnetization $A(m)\ensuremath{\sim}{m}^{1.8}$ valid for a wide range of temperatures. For hcp Co we find an anisotropic domain wall width in the range 24--29 nm which increases with temperature. The results form a critical input for large-scale temperature-dependent micromagnetics simulations and demonstrate the importance of correct parametrization for accurate simulation of magnetization dynamics.

The presence of an exchange field in topological insulators reveals novel spin related phenomena derived from the combination of topology and magnetism. In the present work we show the controlled occurrence of either metallic or gapped topological Dirac states at the interface between ultrathin Cr films and the ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ surface. The opening and closing of the gap at the Dirac point is caused by the spin reorientation transitions arising in the Cr films. We find that atom-thin layers of Cr adhered to ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ surfaces present a magnetic ground state with ferromagnetic planes coupled antiferromagnetically. As the thickness of the Cr film increases stepwise from one to three atomic layers, the direction of the magnetization changes twice from out of plane to in plane and to out of plane again. The out-of-plane magnetization drives the gap opening and the topological surface states acquire a circular meron spin structure. Therefore, the Cr spin reorientation leads to the metal-insulator transition in the ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ surface and to the correlated modification of the surface-state spin texture. Consequently, the thickness of the Cr film provides an effective and controllable mechanism to modify the metallic or gapped nature, as well as the spin texture of the topological Dirac states.

The recent proposal of a direct equivalence between the p-type doping typically found in quasi-free-standing graphene (QFG) obtained on H-passivated silicon carbide surface and the spontaneous polarization (SP) associated to the particular SiC polytype, opens the possibility of tuning the number of carriers in the Dirac cones without the need of external gate voltages. However, first-principles calculations which could confirm at the atomic scale the effect of the SP are lacking mainly due to the difficulty of combining a bulk property such as the SP with the surface confined graphene doping. Here we develop an approach based on standard density functional theory (DFT) calculations in order to quantify the effect of the SP on the QFG’s doping level. To this end, a double gold layer is attached at the C-terminated bottom of the slab which introduces a metal-induced gap state that pins the chemical potential inside the gap thus allowing a meaningful comparison of the QFG’s dopings among different polytypes. Our model is generalized by performing large-scale DFT calculations where self-doping in the QFG is included via point defects in order to estimate the interplay between both sources of p-type doping (SP- versus defect-induced) which turns out to be essentially additive., This work was supported by the Spanish Ministry of Innovation and Science under contract Nos. MAT2013-47878-C2-R and MAT2012-38045-C04-04. J.S. acknowledges Polish Ministry of Science and Higher Education for financing the postdoctoral stay at the ICMM-CSIC in the frame of the program Mobility Plus.

In this paper it will be argued that there are two different and equally relevant factors intervening in the creation and interpretation of noun-noun sequences in English. On the one hand, the concepts denoted by the nouns involved will determine some preferences to combine with other nouns, since certain semantic relations are cognitively salient with each semantic type of noun and are therefore privileged. By means of corpus data it will be shown that there are two main types of conceptual relations holding between the two nouns in a sequence, depending on the semantics of the nouns, namely argument relations and adverbial relations. On the other hand, it will be claimed that conceptual combination is a dynamic process that must take context (either world-knowledge, co-text, or situational context) into account.

The vibrational modes of cylindrical shells with transverse elastic isotropy and arbitrary thickness are calculated in the framework of the elasticity theory and a comparison with the isotropic approach is presented. Cylindrical shells are a good model for nanotubes and here an application for nanotubes of transversely isotropic elastic materials is given. We have obtained the expression for the frequency of the radial breathing mode and it is shown that calculated frequencies coming from that expression compare fairly well with those obtained from different ab initio, force constant model calculations and experimental results. Further, the dispersion relations depend on all the elastic coefficients and therefore they are quite different for nanotubes with hexagonal or wurtzite structure. This demonstrates the need to go beyond the isotropic model to investigate the vibrational spectrum of transversely isotropic elastic material nanotubes and nanowires.

Yttria-stabilized zirconia strengthened with lamellar flaky-shape Nb metal particles was obtained by hot-pressing at 1500 °C for 1 h. The ZrO2–Nb interface has been studied by atomistic, first-principles calculations and by high-resolution transmission electron microscopy. The influence of the ceramic–metal interface on the crack growth resistance has been investigated. Crack growth is shown to occur with a rising resistance, governed by intact metal ligaments in the crack wake. Crack extension occurs by a combination of plastic deformation on the metal particles and interface debonding. The connection between the interface adhesion and this microstructural toughening mechanism has been evaluated.

© 2015 Macmillan Publishers Limited. All rights reserved. A plethora of technological applications justify why titanium dioxide is probably the most studied oxide, and an optimal exploitation of its properties quite frequently requires a controlled modification of the surface. Low-energy ion bombardment is one of the most extended techniques for this purpose and has been recently used in titanium oxides, among other applications, to favour resistive switching mechanisms or to form transparent conductive layers. Surfaces modified in this way are frequently described as reduced and defective, with a high density of oxygen vacancies. Here we show, at variance with this view, that high ion doses on rutile titanium dioxide (110) induce its transformation into a nanometric and single-crystalline titanium monoxide (001) thin film with rocksalt structure. The discovery of this ability may pave the way to new technical applications of ion bombardment not previously reported, which can be used to fabricate heterostructures and interfaces.

This article reviews the present state of research on metal–zirconia interfaces. Interfaces play a crucial role in establishing the macroscopic properties and performance of zirconia-based heterogeneous materials, particularly composites and layered structures, which have a major significance in an extraordinary variety of industrial and technological applications. We have compiled the results reported on recent experimental and theoretical investigations which address the understanding of the nature and strength of the interface interactions from the macroscopic length scale to the atomic characterization. We have mainly focused on microscopic experimental results and ab initio atomistic calculations of diverse metal–zirconia systems, which are limited by the requirement of low misfit between the metal and ZrO2 lattices. However, systematic investigations of the wettability of zirconia surfaces by liquid metals and of the mechanical properties of cermets and layered structures are also compiled, since they are intimately related to the strength of the interaction between metals and zirconia. Most applications use stabilized ZrO2 phases doped with aliovalent oxides, where the electronic and structural properties of the ideal ZrO2 lattice are significantly altered due to the combined presence of O vacancies and substitutional dopant cations. The existence of such defects has a significant impact on the metal adhesion, as evidenced both in the experiments and calculations. Additionally, the spontaneous structural transformation of zirconia in the presence of oxygen vacancies can occur, and its role in the interface interactions is explored.

An investigation was conducted on the effect of transcranial magnetic field stimulation (TMS) on the free radical production and neuronal cell loss produced by 3-nitropropionic acid in rats. The effects of 3-nitropropionic acid were evaluated by examining the following changes in: the quantity of hydroperoxides and total radical-trapping antioxidant potential (TRAP), lipid peroxidation products, protein carbonyl groups, reduced glutathione (GSH) content, glutathione peroxidase (GSH-Px), catalase and succinate dehydrogenase (SDH) activities; total nitrite and cell death [morphological changes, quantification of neuronal loss and lactate dehydrogenase (LDH) levels]. Our results reveal that 3-nitropropionic acid induces oxidative and nitrosative stress in the striatum, prompts cell loss and also shows that TMS prevents the harmful effects induced by the acid. In conclusion, the results show the ability of TMS to modify neuronal response to 3-nitropropionic acid.

The purpose of this study was to analyze the interaction between caloric restriction (CR) and the dwarf mutation at the level of insulin sensitivity and signal transduction. To this end, we analyzed the in vivo status of the insulin signaling system in skeletal muscle from Ames dwarf (df/df) and normal mice fed ad libitum or subjected to short-term (20-day) CR. We measured insulin-stimulated phosphorylation of the IR and IRS-1, IRS-1-p85 association and Akt activation, and the abundance of the IR, IRS-1, p85, GLUT-4 and IGF-1 receptor in skeletal muscle. In terms of glucose homeostasis, the response to CR was different in both groups of animals. In normal animals, CR induced a significant reduction in both circulating insulin and glucose levels, while CR did not modify these parameters in df/df mice. We did not find any significant alteration in either activation or abundance of signaling molecules analyzed after short-term CR in either normal or Ames dwarf mice. We conclude that the initial adaptation to CR in normal mice is an increase in insulin sensitivity without changes in insulin signal transduction, and that this adaptation is not evidenced in df/df mice, probably since they are already hypersensitive to insulin.

The effect of red wine on oxidative stress and hypercholesterolemia induced by feeding a high-cholesterol diet (supplemented with 1.65% of cholesterol (w/w) for 4 weeks) to female Wistar rats was examined. When red wine was simultaneously supplemented to high-cholesterol diet, total cholesterol, triglycerides, atherogenic index and lipid peroxidation products significantly decreased compared with the high-cholesterol diet alone, while GSH content and antioxidative enzymes activities were enhanced. In the hypercholesterolemic rat the excretion of fecal bile acids, as well as their plasma and hepatic concentrations were increased significantly. Administration of red wine enhanced these values, indicating an increase in the cholesterol degradation. These results suggest that red wine may have a protective effect against oxidative stress, hypercholesterolemia and atherogenic index induced by high-cholesterol diet.

To explore if protective effect of melatonin on oxidative stress induced by okadaic acid, an inhibitor of protein phosphatases PP1 and PP2A, is mediated by membrane receptors subtype mt1, we used an in vitro model with N1E-115 neuroblastoma cells. We demonstrated that exposure of cells to 50 nM okadaic acid for 2 h induces a reduction in the activity of antioxidative enzymes, and an increase of lipid peroxidation products, while melatonin prevents the effect of okadaic acid. On the other hand, the presence of luzindole, 20 min before adding melatonin, did not cause changes on the effect of the melatonin on oxidative stress. These results seem to indicate that protective effect of melatonin is not mediated by mt1 receptors.

The c(2 × 2)MnCu surface alloy on Cu(100) can be considered as a purely two-dimensional magnetic system where the Mn atoms exhibit a large corrugation closely related to their high spin moment. In this paper we investigate the influence of the atomic environment on the electronic and magnetic properties of the two-dimensional alloyed layer, extending our study to the less known multilayered system made of MnCu two-dimensional alloy layers embedded in a Cu crystal. The analysis is based on angle-resolved photoelectron spectroscopy measurements and calculations using the Green function matching method, which allows us to treat exactly the projection of the three-dimensional lattice on the c(2 × 2) plane. A complete study of the valence band is performed along the two-dimensional Brillouin zone in a wide energy range. We show that the presence of Mn results in an important redistribution of the spin-polarized electronic states of the neighbouring Cu atoms. This redistribution is not accompanied by a net charge transfer between different atoms, and also the spin moment of Cu remains small. Most of the new features induced by Mn in the surface alloy are also present in the multilayered system, evidencing that they are specific to the two-dimensional alloyed layer and not surface effects.

A detailed study of the electronic structure of the c(2×2)-MnCu/Cu(0 0 1) surface alloy at the Fermi level is presented. We show that the complex topology of the two-dimensional momentum distribution of the electrons is due to the sum of two effects: the projection of the bulk Fermi surface onto the (2×2) plane, and the presence of new electronic states induced by the minority spin band of Mn. The crucial role of the surface potential in the intensity and dispersion of the states is discussed.

The interaction between Ni(001) and cubic-ZrO2(001) surfaces is investigated, focusing on the role of the O vacancies that actually exist in the c-ZrO2 phase stabilized at room temperature. Ab-initio calculations of the electronic charge distribution are performed, allowing full relaxation of the atomic positions. The results indicate a weakening of the Ni–O interactions at the interface, in favour of a change of the Zr–O coordination to adopt configurations closer to the stable low temperature phases.

Recently, numerous studies have shown antioxidant actions of melatonin. Melatonin at both physiological and pharmacological levels stimulates glutathione peroxidase, glutathione reductase and superoxide dismutase activities in the brains of rats and chickens. This study was designed to evaluate the effect of melatonin on nephropathy and oxidative stress under constant light exposure. Nephropathy was induced by adriamycin administered in a single dose (25 mg kg−1 b.w., i.p.). Melatonin was injected i.p. (1000 μg kg−1 b.w./day). Malondialdehyde, reduced glutathione, glutathione peroxidase, glutathione reductase, glutathione transferase, catalase and superoxide dismutase were determined in kidney. Urea, creatinine and total proteins in plasma and proteinuria were evaluated and melatonin was determined. Results show a decrease in melatonin levels. Similar effects occurred with the antioxidant enzyme activities and reduced glutathione. Likewise, adriamycin and constant light induced significant enhancement of malondialdehyde. All changes induced both by adriamycin and constant light were reverted to normal by melatonin administration. Constant light exposure was associated with an increase in oxidative stress and nephropathy induced by adriamycin. Treatment with melatonin decreased lipid peroxides, and permitted a recovery of reduced glutathione, scavenger enzyme activity and parameters of renal function. Copyright © 2002 John Wiley & Sons, Ltd.

To determine the degree of tumor necrosis in surgical specimens of hepatocellular carcinomas treated with microspheres preloaded with doxorubicin and to analyze the relationship between the degree of necrosis and a) morphologic factors and b) imaging biomarkers.We studied the livers of 21 patients who had undergone selective arterial chemoembolization with DC beads (Biocompatibles, UK) before receiving liver transplants.Imaging techniques detected 43 nodules (mean size, 25 mm). Angiography showed 25 hypervascularized nodules, 12 slightly vascularized nodules, and 6 avascular nodules. A total of 81 hepatocellular carcinomas (mean size, 15 mm) were detected in the specimens: two were capsular and two had vascular infiltration. The mean degree of necrosis after chemoembolization was 39%; necrosis was greater than 60% in 28 hepatocellular carcinomas and less than 60% in 52. The degree of necrosis correlated significantly with the time elapsed between the last chemoembolization treatment and liver transplantation (the degree of necrosis decreased as time increased), with the number of nodules in the specimen, and with capsular infiltration. When imaging techniques detected 1 or 2 nodules, there was a greater probability of achieving greater than 90% necrosis. No relation with the degree of necrosis achieved was found for the size of the nodules detected at imaging, the enhancement pattern, or the number of chemoembolization treatments.The degree of necrosis achieved depends on the time spent on the waiting list, on the number of nodules in the specimen, and on whether capsular infiltration is present.

The aims of the present study were first to compare the effects of melatonin and vitamin E on the cholestasis syndrome and their protective effect on liver injury, and second, to evaluate the activity of antioxidant enzymes after treatment with these antioxidant drugs. Cholestasis was achieved in adult male Wistar rats by double ligature and section of the extra-hepatic biliary duct. Hepatic and plasma oxidative stress markers were evaluated by changes in the amount of lipid peroxides, measured as malondialdehyde (MDA) and reduced glutathione (GSH) in plasma and homogenates of hepatic tissue. Serum bilirubin, alkaline phosphatase (AP), and gamma-glutamyl-transpeptidase (GGT) were used to evaluate the severity of cholestasis, and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were used to evaluate the hepatic injury. Both vitamin E and melatonin were administrated 1 day before and 7 days after bile duct ligation. Acute ligation of the bile duct was accompanied by a significant increased in MDA and a decrease in GSH levels in both plasma and liver, as well as a significant reduction in antioxidant enzymes activities. The overall analysis of both treatments showed that melatonin (500 microg/kg daily) offered significantly better protection against cholestasis and a superior protective effect on hepatic injury than did vitamin E (15 mg/kg daily). Although vitamin E treatment resulted in a reduction of parameters of oxidative stress, the results were significantly better after a much lower daily dose of melatonin. Moreover, melatonin treatment was associated with a significant recovery of antioxidative enzymes. In conclusion, the present paper demonstrates a correlation between the intensity of biliary tract obstruction and increased free radical generation, as well as a direct correlation between the level of oxidative stress and the biochemical markers of liver injury. Melatonin (at a much lower dose than vitamin E) was much more efficient than vitamin E in reducing the negative parameters of cholestasis, the degree of oxidative stress and provided a significantly greater hepatoprotective effect against the liver injury secondary to the acute ligation of the biliary duct.

Reptiles can harbor pathogenic microorganisms asymptomatically and serve as potential reservoirs of infection for humans, domestic animals, and other reptiles. Infectious diseases are also problematic for free-ranging reptile populations and are an important consideration in reptile reintroduction and translocation projects. There have been limited serologic studies of free-ranging reptiles for evidence of exposure to potential pathogens. In the present study, serum or plasma samples from five male and five female free-ranging Venezuelan anacondas ( Eunectes murinus) were screened for antibodies to eastern, western, and Venezuelan equine encephalitis viruses, vesicular stomatitis virus, ophidian paramyxovirus, 19 Leptospira interrogansserovars, and Cryptosporidium serpentes . Antibodies to these agents were not detected, or antibody titers were low and possibly nonspecific. These results for the limited number of anacondas surveyed suggest that they do not serve as significant reservoirs for these infectious agents at this location.

In the present study we investigate the electronic structure of the c(2×2)Mn/Cu(1 0 0) surface alloy which is formed by adsorption of 0.5 ML of Mn on Cu(1 0 0) at room temperature. We show that the electronic structure of the MnCu surface alloy is very different to that of the clean Cu(1 0 0) surface. We focus our investigation on the electronic structure related to electronic states close to the Fermi edge. The experimental synchrotron ultraviolet photoemission spectroscopy results are compared with theoretical calculations based on the surface Green's function matching technique, using a semiempirical tight-binding hamiltonian. The theoretical results are in very good agreement with the experimental ones and confirm the surface origin of the observed new spectral features.

The surface electronic configuration of Pt3Mn(111) and layered (2×2) Pt/Pt3Mn(111) compounds within a parametrized tight-binding scheme is calculated by means of the Surface Green Function Matching method. The effects of the spin-orbit coupling within the central cell approach are studied in detail, concerning both the layer density of states and the atomic magnetic moments. A discussion of the surface magneto-optical properties involved is included.

The way that herpetologists have traditionally measuredlive snakes is by stretching them on a ruler andrecording the total length (TL). However, due to the thinconstitution of the snake, the large number of intervertebraljoints, and slim muscular mass of most snakes,it is easier to stretch a snake than it is to stretch anyother vertebrate. The result of this is that the length ofa snake recorded is infl uenced by how much the animalis stretched. Stretching it as much as possible is perhapsa precise way to measure the length of the specimenbut it might not correspond to the actual length ofa live animal. Furthermore, it may seriously injure a livesnake. Another method involves placing the snake in aclear plexiglass box and pressing it with a soft materialsuch as rubber foam against a clear surface. Measuringthe length of the snake may be done by outlining itsbody with a string (Fitch 1987; Frye 1991). However, thismethod is restricted to small animals that can be placedin a box, and in addition, no indications of accuracy of thetechnique are given. Measuring the snakes with a fl exibletape has also been reported (Blouin-Demers 2003)but when dealing with a large animals the way the tapeis positioned can produce great variance on the fi nal outcome.In this contribution we revise alternative ways tomeasuring a snake and propose a method that offers repeatableresults. We further analyze the precision of thismethod by using a sample of measurements taken fromwild populations of green anacondas (Eunectes murinus)with a large range of sizes.

A pure carbon quantum dot can be designed by introducing pentagon-heptagon defects in a carbon nanotube. This system has completely confined electronic states induced by the presence of topological defects. By varying the distance between the pentagon-heptagon pairs, the energy difference, spatial confinement, and number of discrete levels can be modified, thus opening a way for carbon-nanotube-based engineering of zero-dimensional systems.

Calculations of the Fermi surfaces of Co/Ni (001) and (111) superlattices, based on a tight-binding model and on a Green function approach, reveal that superlattice Fermi surfaces have a tubular structure with a highly anisotropic cylindrical topology. The superlattice potential changes the cubic symmetry of Co and Ni and leads to undulating multisheeted cylindrical Fermi surfaces with marked two-dimensional character and strong nesting in both perpendicular and growth directions. The uncommon superlattice topology may result in unique properties. In particular, large anisotropic transport coefficients and electronic instabilities associated to coupled points on the Fermi surface are expected.

The effect of melatonin (MEL) on the nephropathy and the oxidative stress induced by a single and high dose of Adriamycin (AD) has been studied in Wistar male rats. MEL (50 microg/kg/day) was injected intraperitoneally 3 and 7 days, respectively, before and after AD injection (20 mg/kg i.p.). Trunk blood was drawn and triglycerides, total cholesterol, phospholipids, high-density lipoprotein cholesterol, urea, creatinine, total protein, lipoperoxides, and reduced glutathione (GSH) levels and catalase activity (CAT) were determined in serum. In kidney homogenates, lipoperoxides, GSH, and CAT were measured as well as total protein in urine. AD administration resulted in hyperlipidemia and high-grade proteinuria and a marked increase in serum lipoperoxides, urea, and creatinine. In the kidney, the increase in lipoperoxides was accompanied by a significant decrease of GSH and CAT. The efficiency of MEL was specially remarkable in restoring GSH, CAT, and proteinuria to the levels of controls. These results confirm the involvement of free radicals in the pathogenesis of nephrotoxicity induced by AD. Likewise, they show the high antioxidative power of MEL and its marked effect on the prevention and suppression of this nephropathy.