Validity of the scaling functional approach for polymer interfaces as a variational theory

We discuss the soundness of the scaling functional (SF) approach proposed by Aubouy Guiselin and Raphael (Macromolecules 29, 7261 (1996)) to describe polymeric interfaces. In particular, we demonstrate that this approach is a variational theory. We emphasis the role of SF theory as an important link between ground-state theories suitable to describe adsorbed layers, and "classical" theories for polymer brushes.Comment: 8 pages, 1 figure, to be published in Phys. Rev.

Serological Survey of Antibodies to Mannheimia haemolytica and Pasteurella multocida in Camelids from Argentina

South American camelids are a source of livestock wealth in Andean countries. In Argentina,there is little information about camelid pathogens, and most of the literature data available areseroprevalence works against virus. Besides, little is known about the immunological status againstbacterial agents affecting these animals. In an effort to explore the serological status of Argentineancamelids, we evaluated the presence of serum antibodies against bacterial pathogens involved inpneumonic diseases (Pasteurella multocida and Mannheimia haemolytica) in llamas from differentregions of the country. By ELISA, a high seroprevalence for both pathogens was found in the serumsamples; higher optical density (OD) values were obtained when the sera were incubated with heatkilledP. multocida as coating antigen compared to M. haemolytica. In addition, a large number ofsera analyzed presented high OD values for both microorganisms independently of their originregion. Serum avidity was also evaluated, by means of an assay based on antibody desorption byurea. No correlation was found between the high ODs obtained for P. multocida and the serumavidity. On the other hand, samples reacting with M. haemolytica had lower OD values but higheravidity index. The antigenic recognition pattern for both microorganisms was determined bywestern blot. Unlike P. multocida, the antigenic recognition pattern of M. haemolytica did not differamong serum samples obtained from animals living in different areas. In summary, we found thatcamelids can synthetize antibodies that recognize M. haemolytica with high avidity for differentantigens of the bacterium, suggesting that Argentinean camelids are in contact with M. haemolyticawhich is probably a causative agent of subclinical infections. Conversely, specific antibodies forP. multocida were also found, but these sera presented low avidity that is probably the result of acolonization process by this bacterium, or else, to be a consequence of cross-reactivity phenomenaFil: Díaz, Ailén Magalí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Ledesma, Martin Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Calcagno, M. L.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Físico Matemática. Cátedra de Matemáticas; ArgentinaFil: Leoni, Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Manghi, Marcela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Canellada, Andrea Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; ArgentinaFil: Castro, Marisa Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral Prof. Ricardo A. Margni; Argentin

Effects of electronic correlation on X-Ray absorption and dichroic spectra at L2,3_{2,3} edge

We present a new theoretical approach to describe X-Ray absorption and Magnetic Circular Dichroism spectra in the presence of e-e correlation. Our approach provides an unified picture to include correlations in both charged and neutral excitations, namely in direct / inversion photoemission where electrons are removed/added, and photo absorption where electrons are promoted from core levels to empty states. We apply this approach to the prototypical case of L$_{2,3}$ edge of 3$d$ transition metals and we show that the inclusion of many body effects in the core level excitations is essential to reproduce, together with satellite structures in core level photoemission, the observed asymmetric line shapes in X-ray absorption and dichroic spectra.Comment: 3 figures, 5 pages, submitted to Phys. Rev.

Raman signatures of classical and quantum phases in coupled dots: A theoretical prediction

We study electron molecules in realistic vertically coupled quantum dots in a strong magnetic field. Computing the energy spectrum, pair correlation functions, and dynamical form factor as a function of inter-dot coupling via diagonalization of the many-body Hamiltonian, we identify structural transitions between different phases, some of which do not have a classical counterpart. The calculated Raman cross section shows how such phases can be experimentally singled out.Comment: 9 pages, 2 postscript figures, 1 colour postscript figure, Latex 2e, Europhysics Letters style and epsfig macros. Submitted to Europhysics Letter

Exclusion of the 'secondary student'. Multimodal analysis in Chilean media

Indexación ScopusEste estudio muestra cómo tres medios de comunicación de Chile construyen multimodalmente al actor social ‘estudiantes secundarios’. Se aborda la manera en que Televisión Nacional de Chile, El Dínamo y El Ciudadano representan a este grupo social que frecuentemente es suprimido de la esfera mediática. La metodología es cualitativa con un enfoque semiótico social, siguiendo los lineamientos de la Gramática Visual y la tipología de actores sociales de van Leeuwen (2003). El corpus consideró 15 textos multimodales del 2018 recopilados de sitios de internet, que constituyen una cadena semiótica de un evento noticioso sobre educación. Los resultados sugieren que TVN crea el significado de un ‘estudiante agresor’, El Dínamo de un ‘estudiante a corregir’; en cambio, El Ciudadano lo representa como un actor social que es un ‘participante activo’.This study shows how three Chilean media construct in their discourse the social actor 'secondary students', in a multimodal way. It focuses on the representation of Televisión Nacional de Chile (also known as TVN), El Dínamo and El Ciudadano of this social group which is often suppressed suppressed from the media sphere. It is a qualitative study with a social semiotic approach, following the guidelines of Visual Grammar and the typology of representation of social actors by van Leeuwen (2003). The corpus comprised 15 multimodal texts of 2018 compiled from internet sites, which constitute a semiotic chain of a news event about education. The results suggest that TVN creates the meaning of an 'aggressor student', El Dínamo as a 'student to be reformed'; whereas El Ciudadano, represents him as a social actor who is an 'active participant'. © Este trabajo se encuentra bajo la licencia Creative Commons Attribution 3.0.https://revistas.userena.cl/index.php/logos/article/view/138

On-site correlation in valence and core states of ferromagnetic nickel

We present a method which allows to include narrow-band correlation effects into the description of both valence and core states and we apply it to the prototypical case of nickel. The results of an ab-initio band calculation are used as input mean-field eigenstates for the calculation of self-energy corrections and spectral functions according to a three-body scattering solution of a multi-orbital Hubbard hamiltonian. The calculated quasi-particle spectra show a remarkable agreement with photoemission data in terms of band width, exchange splitting, satellite energy position of valence states, spin polarization of both the main line and the satellite of the 3p core level.Comment: 14 pages, 10 PostScript figures, RevTeX, submitted to PR

Interfacial magnetic structure in Fe/NiO(001)

Using nuclear resonant scattering of synchrotron radiation and density functional theory calculations we haveresolved the magnetic properties of the different Fe phases present at the Fe/NiO(001) interface, an epitaxialferromagnetic/antiferromagnetic system. We have detected the presence of an interfacial antiferromagneticFeO-like phase with a significantly increased magnetic moment compared to the case of a sharp interface.Already a few atomic layers above the interface, the Fe atoms have a bulk-like metallic character and the reversalof their magnetization is strongly influenced by the antiferromagnetic layer

Activity distribution of comet 67P/Churyumov-Gerasimenko from combined measurements of non-gravitational forces and torques

Aims. Understanding the activity is vital for deciphering the structure, formation, and evolution of comets. We investigate models of cometary activity by comparing them to the dynamics of 67P/Churyumov-Gerasimenko. Methods. We matched simple thermal models of water activity to the combined Rosetta datasets by fitting to the total outgassing rate and four components of the outgassing induced non-gravitational force and torque, with a final manual adjustment of the model parameters to additionally match the other two torque components. We parametrised the thermal model in terms of a distribution of relative activity over the surface of the comet, and attempted to link this to different terrain types. We also tested a more advanced thermal model based on a pebble structure. Results. We confirm a hemispherical dichotomy and non-linear water outgassing response to insolation. The southern hemisphere of the comet and consolidated terrain show enhanced activity relative to the northern hemisphere and dust-covered, unconsolidated terrain types, especially at perihelion. We further find that the non-gravitational torque is especially sensitive to the activity distribution, and to fit the pole-axis orientation in particular, activity must be concentrated (in excess of the already high activity in the southern hemisphere and consolidated terrain) around the south pole and on the body and neck of the comet over its head. This is the case for both the simple thermal model and the pebble-based model. Overall, our results show that water activity cannot be matched by a simple model of sublimating surface ice driven by the insolation alone, regardless of the surface distribution, and that both local spatial and temporal variations are needed to fit the data. Conclusions. Fully reconciling the Rosetta outgassing, torque, and acceleration data requires a thermal model that includes both diurnal and seasonal effects and also structure with depth (dust layers or ice within pebbles). This shows that cometary activity is complex. Nonetheless, non-gravitational dynamics provides a useful tool for distinguishing between different thermophysical models and aids our understanding

About the strength of correlation effects in the electronic structure of iron

The strength of electronic correlation effects in the spin-dependent electronic structure of ferromagnetic bcc Fe(110) has been investigated by means of spin and angle-resolved photoemission spectroscopy. The experimental results are compared to theoretical calculations within the three-body scattering approximation and within the dynamical mean-field theory, together with one-step model calculations of the photoemission process. This comparison indicates that the present state of the art many-body calculations, although improving the description of correlation effects in Fe, give too small mass renormalizations and scattering rates thus demanding more refined many-body theories including non-local fluctuations.Comment: 4 pages, 4 figure