First-principles transport calculation method based on real-space finite-difference nonequilibrium Green's function scheme

We demonstrate an efficient nonequilibrium Green's function transport calculation procedure based on the real-space finite-difference method. The direct inversion of matrices for obtaining the self-energy terms of electrodes is computationally demanding in the real-space method because the matrix dimension corresponds to the number of grid points in the unit cell of electrodes, which is much larger than that of sites in the tight-binding approach. The procedure using the ratio matrices of the overbridging boundary-matching technique [Phys. Rev. B {\bf 67}, 195315 (2003)], which is related to the wave functions of a couple of grid planes in the matching regions, greatly reduces the computational effort to calculate self-energy terms without losing mathematical strictness. In addition, the present procedure saves computational time to obtain Green's function of the semi-infinite system required in the Landauer-B\"uttiker formula. Moreover, the compact expression to relate Green's functions and scattering wave functions, which provide a real-space picture of the scattering process, is introduced. An example of the calculated results is given for the transport property of the BN ring connected to (9,0) carbon nanotubes. The wave function matching at the interface reveals that the rotational symmetry of wave functions with respect to the tube axis plays an important role in electron transport. Since the states coming from and going to electrodes show threefold rotational symmetry, the states in the vicinity of the Fermi level, whose wave function exhibits fivefold symmetry, do not contribute to the electron transport through the BN ring.Comment: 34 page

Conectividad molecular. Su aplicación a algunas propiedades físico-químicas de un grupo de alcoholes

Se ha aplicado el método de Conectividad Molecular a un grupo de alcoholes, usando como propiedades a correlacionar: la refracción molar, la entalpia de formación y la temperatura de ebullición, y como índices topológicos los de Kier y Hall y los geométricos. Los resultados indican que en estudios de relación estructura-actividad, así como en los de predicción, los índices geométricos son adecuados para propiedades moleculares (Rrn, ∆Hf), mientras que los de Kier y Hall lo son para propiedades molares (Te).Molecular connectlvlty method has been used for studying sorne physico chemical properties, such as molar refraction, heat of formation and boiling point, in a group of alcohols, using the Kier and Hall's and geometrical indices. The results indicate that these are the better for molecular properties (i.e. molar refraction and heat of formation), while Kier and Hall's were for molar properties (i.e. boiling temperature)

Conectividad molecular. Su aplicación a algunas propiedades físico-químicas de un grupo de alcoholes

Molecular connectlvlty method has been used for studying sorne physicochemical properties, such as molar refraction, heat of formation and boiling point, in a group of alcohols, using the Kier and Hall's and geometrical indices. The results indicate that these are the better for molecular properties (i.e. molar refraction and heat of formation), while Kier and Hall's were for molar properties (i.e. boiling temperature).Se ha aplicado el método de Conectividad Molecular a un grupo de alcoholes, usando como propiedades a correlacionar: la refracción molar, la entalpia de formación y la temperatura de ebullición, y como índices topológicos los de Kier y Hall y los geométricos. Los resultados indican que en estudios de relación estructura-actividad, así como en los de predicción, los índices geométricos son adecuados para propiedades moleculares (Rrn,  ∆Hf), mientras que los de Kier y Hall lo son para propiedades molares (Te)

Surface effects in color superconducting strange-quark matter

Surface effects in strange-quark matter play an important role for certain observables which have been proposed in order to identify strange stars, and color superconductivity can strongly modify these effects. We study the surface of color superconducting strange-quark matter by solving the Hartree-Fock-Bogoliubov equations for finite systems ("strangelets") within the MIT bag model, supplemented with a pairing interaction. Due to the bag-model boundary condition, the strange-quark density is suppressed at the surface. This leads to a positive surface charge, concentrated in a layer of ~1 fm below the surface, even in the color-flavor locked (CFL) phase. However, since in the CFL phase all quarks are paired, this positive charge is compensated by a negative charge, which turns out to be situated in a layer of a few tens of fm below the surface, and the total charge of CFL strangelets is zero. We also study the surface and curvature contributions to the total energy. Due to the strong pairing, the energy as a function of the mass number is very well reproduced by a liquid-drop type formula with curvature term.Comment: 13 pages, v2: more detailed explanations, discussion adde

On the Origin of the -4.4 eV Band in CdTe(100)"

We calculate the bulk- (infinite system), (100)-bulk-projected- and (100)-Surface-projected Green's functions using the Surface Green's Function Matching method (SGFM) and an empirical tight-binding hamiltonian with tight-binding parameters (TBP) that describe well the bulk band structure of CdTe. In particular, we analyze the band (B--4) arising at --4.4 eV from the top of the valence band at $\Gamma$ according to the results of Niles and H\"ochst and at -4.6 eV according to Gawlik {\it et al.} both obtained by Angle-resolved photoelectron spectroscopy (ARPES). We give the first theoretical description of this band.Comment: 17 pages, Rev-TEX, CIEA-Phys. 02/9

Surface plasmons at composite surfaces with diffusive charges

Metal surfaces with disorder or with nanostructure modifications are studied, allowing for a localized charge layer (CL) in addition to continuous charges (CC) in the bulk, both charges having a compressional or diffusive non-local response. The notorious problem of "additional boundary conditions" is resolved with the help of a Boltzmann equation that involves the scattering between the two charge types. Depending on the strength of this scattering, the oscillating charges can be dominantly CC or CL; the surface plasmon (SP) resonance acquires then a relatively small linewidth, in agreement with a large set of data. With a few parameters our model describes a large variety of SP dispersions corresponding to observed data.Comment: 6 pages, 2 figure

Multicentric standardization of protocols for the diagnosis of human mitochondrial respiratory chain defects

The quantification of mitochondrial respiratory chain (MRC) enzymatic activities is essential for diagnosis of a wide range of mitochondrial diseases, ranging from inherited defects to secondary dysfunctions. MRC lesion is frequently linked to extended cell damage through the generation of proton leak or oxidative stress, threatening organ viability and patient health. However, the intrinsic challenge of a methodological setup and the high variability in measuring MRC enzymatic activities represents a major obstacle for comparative analysis amongst institutions. To improve experimental and statistical robustness, seven Spanish centers with extensive experience in mitochondrial research and diagnosis joined to standardize common protocols for spectrophotometric MRC enzymatic measurements using minimum amounts of sample. Herein, we present the detailed protocols, reference ranges, tips and troubleshooting methods for experimental and analytical setups in different sample preparations and tissues that will allow an international standardization of common protocols for the diagnosis of MRC defects. Methodological standardization is a crucial step to obtain comparable reference ranges and international standards for laboratory assays to set the path for further diagnosis and research in the field of mitochondrial diseases. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Calibration and performance tests of detectors for laser-accelerated protons

We present the calibration and performance tests carried out with two detectors for intense proton pulses accelerated by lasers. Most of the procedures were realized with proton beams of 0.46-5.60 MeV from a tandem accelerator. One approach made use of radiochromic films, for which we calibrated the relation between optical density and energy deposition over more than three orders of magnitude. The validity of these results and of our analysis algorithms has been confirmed by controlled irradiation of film stacks and reconstruction of the total beam charge for strongly non-uniform beam profiles. For the spectral analysis of protons from repeated laser shots, we have designed an online monitor based on a plastic scintillator. The resulting signal from a photomultiplier directly measured on a fast oscilloscope is especially useful for time-of-flight applications. Variable optical filters allow for suppression of saturation and an extension of the dynamic range. With pulsed proton beams we have tested the detector response to a wide range of beam intensities from single particles to 3 ×105 protons per 100 ns time interval.Project funded by the Spanish Ministry of Economy and Competitiveness and co-funded with FEDER's funds within the INNPACTO 2011 program under Grant No. IPT-2011-0862-900000. This work was supported by the Spanish Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica (I+D+i) under Grant No. TEC 2013-48036-C3-1-R and the Valencian Local Government under Grants PROMETEOII/2013/010 and ISIC 2011/013. The work of A. J. Gonzalez is financed by CSIC with a JAE-Doc contract under Junta de Ampliacion de Estudios program, cofinanced by the European Social Fund.Peer Reviewe

Fostering Professional Ethical Competence During Teacher Training Practice

Professionals who have undergone their training at university should possess not only the knowledge-base necessary to practice in their chosen profession, but also the ethical principles that ensure responsible professional practice and the corresponding benefits for society. The research project addressed in the present article aimed to contribute to fostering ethical competence and commitment amongst future teachers. During the experience the participants had the opportunity to design tasks that stimulated reflection, critique and ethical awareness.Specialistai, įgiję universitetinį išsilavinimą, turi būti sukaupę ne tik žinių, kurios būtinos profesinėje veikloje, bet ir gebėti vadovautis etikos principais, kurie užtikrintų atsakingą ir visuomenės gerovei reikalingą profesinę veiklą. Tyrime, pristatomame šiame straipsnyje, analizuojamos būsimųjų mokytojų etinės kompetencijos plėtros ir atsidavimo darbui problemos. Tyrimo dalyviai turėjo galimybę kurti užduotis, kurios skatino refleksiją, kritiką ir etinį sąmoningumą.Les professionnels ayant reçu leur formation auprès des Universités disposeront, non seulement des connaissances de base nécessaires à l'exercice de leur métier, mais aussi les principes éthiques garantissant un exercice professionnel responsable portant bénéfice sur la société. Le projet de recherche présenté sous ce titre a comme objectif la contribution à la favorisation de la compétence éthique et de l'engagement parmi les futurs enseignants. Lors de cette expérience, les participants ont eu l'occasion d'élaborer des tâches favorisant la réflexion, la critique et la pensée critique.Профессионалы, получившие университетское образование, не только получают основные знания для работы по своей профессии, но и моральные принципы, которые обеспечивают ответственную профессиональную работу и соответствующую выгоду для общества. Целью исследовательского проекта,представленного под этим именем, является участие в стимуляции профессиональной этики и компромисса среди будущих преподавателей. Во время проведения эксперимента, участники получили возможность разработать задания, стимулирующие размышление, критику и критичиское сознание.Los profesionales que han recibido su formación en la Universidad, poseerán no solo el conocimiento base necesario para la práctica en su profesión, sino también los principios éticos que aseguran la práctica profesional responsable y el correspondiente beneficio para la sociedad. El proyecto de investigación presentado con este título tiene como objetivo contribuir a estimular la competencia ética y el compromiso entre los futuros docentes. Durante la experiencia, los participantes tuvieron la oportunidad de diseñar tareas que estimularan la reflexión, la crítica y la conciencia crítica

Time-of-Flight Detector for the Characterisation of Laser-Accelerated Protons

[Otros] Lasers of ultra-high intensity focused on thin targets can form plasmas and release large numbers of charged particles with kinetic energies in the MeV region. The characterization of the accelerated particles requires suitable detectors. We present a time-of-flight detector based on a plastic scintillator optimized for the spectral analysis of laser-accelerated protons. All details of the detector layout are adapted to the expected properties of the proton beam. Particle energies will be separated by the time-of-flight technique over 200 cm path length. The active area (25 mm width) corresponds to a few mrad opening angle. With 5 mm thickness the detector is capable of absorbing protons up to 22.5 MeV. A very thin, aluminized mylar foil shields the scintillator from outer light while absorbing very little particle energy. The scintillation photons are measured with a photomultiplier tube coupled through a bundle of optical fibres. The coupling of these fibres via a PMMA light guide has been previously optimized in simulations with Litrani. A critical aspect of the detection of virtually large numbers of protons emitted in femtosecond pulses is the saturation of the PMT. The latter can be avoided by use of appropriate optical filters. With these the effective dynamic range starts from single particles over several orders of magnitude. Our time-of-flight detector has been calibrated at the Spanish National Accelerator Centre at Sevilla. Proton beams from 0.46 to 5.6 MeV from a tandem accelerator have been used to measure the relation between particle energy and pulse heights. Further tests have been performed with a pulsed electron beam to simulate many-particle hits.Project funded by the Spanish Ministry of Economy and Competitiveness and co-funded with FEDER¿s funds within the INNPACTO 2011 program, Grant No. IPT-2011-0862- 900000. This work was supported by the Spanish Plan Nacional de Investigacion Científica, Desarrollo e Innovacion Tecnológica (I+D+i) under Grant No. FIS2010-21216-CO2-01 and the Valencian Local Government under Grants PROMETEOII/2013/010 and ISIC 2011/013Seimetz, M.; Bellido, P.; Soriano, A.; Huertas, C.; García Lopez, J.; Jimenez-Ramos, MC.; Fernandez, B.... (2013). Time-of-Flight Detector for the Characterisation of Laser-Accelerated Protons. IEEE. 25-28. https://doi.org/10.1109/NSSMIC.2013.6829804S252