Electronic and magnetic properties of the ionic Hubbard model on the striped triangular lattice at 3/4 filling

We report a detailed study of a model Hamiltonian which exhibits a rich interplay of geometrical spin frustration, strong electronic correlations, and charge ordering. The character of the insulating phase depends on the magnitude of Delta/|t| and on the sign of t. We find a Mott insulator for Delta >> U >> |t|; a charge transfer insulator for U >> \Delta >> |t|; and a correlated covalent insulator for U >> \Delta ~ |t|. The charge transfer insulating state is investigated using a strong coupling expansion. The frustration of the triangular lattice can lead to antiferromagnetism or ferromagnetism depending on the sign of the hopping matrix element, t. We identify the "ring" exchange process around a triangular plaquette which determines the sign of the magnetic interactions. Exact diagonalization calculations are performed on the model for a wide range of parameters and compared to the strong coupling expansion. The regime U >> \Delta ~ |t| and t<0 is relevant to Na05CoO2. The calculated optical conductivity and the spectral density are discussed in the light of recent experiments on Na05CoO2.Comment: 15 pages, 15 figure

Cyclotron effective masses in layered metals

Many layered metals such as quasi-two-dimensional organic molecular crystals show properties consistent with a Fermi liquid description at low temperatures. The effective masses extracted from the temperature dependence of the magnetic oscillations observed in these materials are in the range, m^*_c/m_e \sim 1-7, suggesting that these systems are strongly correlated. However, the ratio m^*_c/m_e contains both the renormalization due to the electron-electron interaction and the periodic potential of the lattice. We show that for any quasi-two-dimensional band structure, the cyclotron mass is proportional to the density of states at the Fermi energy. Due to Luttinger's theorem, this result is also valid in the presence of interactions. We then evaluate m_c for several model band structures for the \beta, \kappa, and \theta families of (BEDT-TTF)_2X, where BEDT-TTF is bis-(ethylenedithia-tetrathiafulvalene) and X is an anion. We find that for \kappa-(BEDT-TTF)_2X, the cyclotron mass of the \beta-orbit, m^{*\beta}_c, is close to 2 m^{*\alpha}_c, where m^{*\alpha}_c is the effective mass of the \alpha- orbit. This result is fairly insensitive to the band structure details. For a wide range of materials we compare values of the cyclotron mass deduced from band structure calculations to values deduced from measurements of magnetic oscillations and the specific heat coefficient.Comment: 12 pages, 3 eps figure

Enquete sobre a realização de pesquisas em centros educacionais no Chile: cumprimentos de aspectos regulatórios éticos e legais

Antecedentes: La investigación en centros educacionales es una fuente frecuente de estudios de las áreas sociales y salud. Objetivo: Determinar el conocimiento y la adherencia a la regulación ética y legal vigente de la investigación realizadas con niños en centros educacionales. Metodología: Estudio transversal tipo encuesta online. Se consultó sobre el nivel de conocimiento y adherencia a la regulación ética y legislación vigente en Chile, para realizar investigación con menores de edad. Resultados: 126 centros respondieron la encuesta; 69% de zonas urbanas; 60% son centros municipales y 34% particulares subvencionados. En un 31,8% de los centros se realizó investigación, 41% de salud y 30,8% de educación. El 27,5% informó que la investigación contaba con aprobación del comité ético-científico para su implementación, un 82% señaló no recibir ni tener conocimiento de los aspectos regulatorios sobre la investigación con seres humanos. Conclusión: Existe bajo conocimiento y adherencia a la regulación ética y legal de la investigación con niños en centros educacionales. Se realizó una jornada de difusión de los resultados y se propuso un flujograma generado por expertos orientado a los directores de centros educacionales para contribuir a la adherencia de los aspectos éticos y regulatorios de la investigación en centros educacionales.Background: Research in educational centers is a frequent source of social and health related studies. Objective: To determine the knowledge and adherence to the current legal and ethical regulations to research performed on children at educational institutions. Methodology: Cross-sectional study online survey-type. The level of knowledge and adherence to the ethical regulation and legislation in Chile, to conduct research with minors was consulted. Results: 126 educational institutions responded the survey; 69% belonged to urban centers; 60% corresponded to those under the Municipality umbrella and 34% to charter schools. Research was performed in 31,8% of the consulted institutions, 41% of the research was on health issues and 30,8% on education. The 27,5% answered that they had the approval of ethical-scientific committee, 82% answered that they neither received nor had any awareness of regulatory aspects on research. Conclusion: There is low knowledge and adherence to ethical and legal regulation to research performed with children in educational centers. A journey for dissemination of results was performed and a flow chart was created by experts and proposed to the school directors to contribute to the adherence of ethical and regulatory aspects of research in educational centers.Antecedentes: A pesquisa em centros educacionais é uma fonte frequente de estudos das áreas sociais e de saúde. Objetivo: determinar o conhecimento e a adesão à regulamentação ética e legal vigente de pesquisa realizada com crianças em centros educacionais. Metodologia: estudo transversal de tipo enquete on-line. Consultou-se sobre o nível de conhecimento e adesão ao regulamento ético e a legislação vigente no Chile, para realizar a pesquisa com menores de idade. Resultados: 126 centros responderam à enquete; 69% em áreas urbanas; 60% são centros municipais e 34% centros particulares subsidiados. Em 31,8% dos centros foram realizadas pesquisas, 41% de saúde e 30,8% de educação. 27,5% relataram que a pesquisa teve aprovação do Comitê de etico-cientifico para a sua execução, 82% disseram não receber ou ter conhecimento dos aspectos regulatórios da pesquisa com seres humanos. Conclusão: Existe pouco conhecimento e adesão ao regulamento ético e legal de pesquisa envolvendo crianças em centros educacionais. Fora realizada uma conferência para a divulgação dos resultados e fora proposto um fluxograma gerado por especialistas, que visam os diretores de centros educacionais para contribuir para a aderência dos aspectos éticos e regulatórios de pesquisa em centros educacionais

Cd38 deficiency ameliorates chronic graft versus Host disease murine lupus via a b-cell dependent mechanism

Trabajo presentado en el II Congreso investigación PTS, celebrado en Granada (España) del 09 al 11 de febrero de 2022.Absence of mouse cell surface receptor CD38 in Cd38-/- mice suggests that this receptor acts as positive regulator of inflammatory and autoimmune responses. Here we report that in the setting of a chronic graft versus host disease (cGVHD) lupus model induced by the transfer of B6.C-H2bm12/KhEg (bm12) spleen cells into co-isogenic Cd38-/- B6 mice causes milder lupus-like autoimmunity with lower levels of anti-ssDNA autoantibodies than the transfer of bm12 spleen cells into WT B6 mice. I In addition, significantly lower percentages of Tfh cells, as well as GC B cells, plasma cells and T-bet+CD11chi B cells are observed in Cd38-/- mice than in WT mice, while the expansion of Treg cells, and Tfr cells is normal, suggesting that the ability of Cd38-/- B cells to respond to allogeneic help from bm12 CD4+ T cells is greatly diminished. The frequencies of T-bet+CD11chi B cells, which are considered the precursors of the autoantibody secreting cells, correlate with anti-ssDNA autoantibody serum levels, with IL-27, and sCD40L. Proteomics profiling of spleens from WT cGVHD mice reflects a STAT1-driven type I IFN-signature, which is absent in Cd38-/- cGVHD mice. Kidney, spleen and liver inflammation was mild and resolved faster in Cd38-/- cGVHD mice than in WT cGVHD mice. We conclude that in B cells CD38 functions as a modulator receptor that controls autoimmune responses

"Bioadsorption of silver ions by calcareous chitin, chitin and chitosan"

"Context: Calcareous chitin, chitin, chitosan, and their modifications are used as bioadsorbents of metals and dyes that cause environmental pollution, endocrine disruption, and human diseases. Aims: To evaluate the selective bioadsorption of silver ions (Ag+ ) by calcareous chitin, chitin, and chitosan. Methods: Experimental and prospective study. The presence of functional groups of the bioadsorbents was identified by Fourier-transformed infrared spectroscopy (FT-IR), 1H-NMR spectroscopy and scanning electron microscopy (SEM). The Langmuir, Freundlich, and Elovich models were applied to describe the adsorption capacity of bioadsorbents according to granule size (20-40, 40-60, 60-80 meshes) and temperature (10, 20, and 30°C). Results: The FT-IR spectrum of calcareous chitin indicates the presence of carbonate (CO3 = 1420 cm-1 ), amide III (1313 cm-1 ), –OH groups (3441.90 cm-1 ), and pyranose structure (952.83 cm-1 ); chitin has –OH groups (3441.90 cm-1 ), NH (3268 cm-1 ), amide I (1654 cm-1 ) and II (1559 cm-1 ); chitosan has –OH groups (3419.90 cm-1 ), –NH (3200 cm-1 ), amide I (1712.18 cm-1 ), –NH2 (1654.46 cm-1 ), amide III (1317.11 cm-1 ) and pyranose structure (1070.12 cm-1 and 1031 cm-1 ). The Langmuir model indicates greater bioadsorption of Ag+ ions at smaller particle sizes (60-80 = 0.25-0.18 mm) and at a temperature of 20-30°C. Conclusions: The bioadsorption of silver ions (Ag+ ) by chitosan is greater with respect to calcareous chitin and chitin; the Langmuir model fits for the Ag+ isotherm and suggests that the process is controlled by physisorption.

Reliability and validity study of the Spanish adaptation of the “Wijma Delivery Expectancy/Experience Questionnaire” (W-DEQ-A)

The Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ-A) is an instrument that evaluates fear of childbirth through the expectations of women in relation to childbirth and their experience during the birth. The objective of this study was to translate the W-DEQ-A into Spanish and analyse its reliability and validity. The study was carried out in two phases: (1) adapting the questionnaire to Spanish and (2) a transversal study in a sample of 273 pregnant women in the Sexual and Reproductive Health centres in the Metropolitan Northern Barcelona in Catalonia (Spain). The psychometric properties were analysed in terms of reliability and construct validity. The confirmatory factorial analysis did not confirm the unidimensionality of the original structure of the WDEQ-A, as happened with the other studies in which it has previously been validated. The result of the exploratory factorial analysis suggests four factors, or dimensions, very similar but not identical to those obtained in other analysis studies of the W-DEQ-A. The Cronbach alpha and the omega scale were also adequate for all the scales and for each of the dimensions. The results of this study confirm the findings of other studies that suggest that the W-DEQ-A is multi-dimensional. In the Spanish version of the W-DEQ-A four dimensions have been identified to explore fear of childbirth in pregnant women. The Spanish version of the WDEQ-A (WDEQ-A-Sp) is reliable and valid for the measurement of fear of childbirth in clinical practice and for use in future research

Validity and reliability of the Spanish version of the “Wijma Delivery Expectancy/Experience Questionnaire” (W-DEQ-B)

The Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ-B) is an instrument that allows the experiences around fear of childbirth to be examined after the birth. It is currently the most widely used to measure different aspects related to the fear of childbirth and enables healthcare and additional assistance to women after birth to be adapted according to their needs. The objective of this study was to translate the W-DEQ-B into Spanish and analyse its reliability and validity. The study was carried out in two phases: (1) transcultural adaption of the questionnaire to Spanish and (2) a transversal study in a sample of 190 postpartum women from Sexual and Reproductive Health Clinics in the province of Barcelona (Spain). The psychometric properties were examined in terms of reliability (internal consistency and temporal stability) and construct validity (confirmatory factorial analysis [CFA] and exploratory factorial analysis [EFA]). The results of the CFA did not confirm unidimensionality of the W-DEQ-B questionnaire. The EFA suggested four very similar, but not identical, dimensions to those obtained in other studies in which the W-DEQ-B has been evaluated. Both the Cronbach's alpha and the omega coefficient were adequate for the total questionnaire and for each of the four dimensions. The results of this study confirm that the W-DEQ-B is multi-dimensional. In the Spanish version of the W-DEQ-B-Sp four dimensions have been identified that allow the experiences around fear of childbirth to be examined after the birth. The Spanish version of the WDEQ-B (WDEQ-B-Sp) is reliable and valid for the measurement of fear of childbirth in clinical practice and for use in future research

Quantifying the Production of Fruit-Bearing Trees Using Image Processing Techniques

[EN] In recent years, the growth rate of world agricultural production and crop yields have decreased. Crop irrigation becomes essential in very dry areas and where rainfall is scarce, as in Egypt. Persimmon needs low humidity to obtain an optimal crop. This article proposes the monitoring of its performance, in order to regulate the amount of water needed for each tree at any time. In our work we present a technique that consists of obtaining images of some of the trees with fruit, which are subsequently treated, to obtain reliable harvest data. This technique allows us to have control and predictions of the harvest. Also, we present the results obtained in a first trial, through which we demonstrate the feasibility of using the system to meet the objectives set. We use 5 different trees in our experiment. Their fruit production is different (between 20 and 47kg of fruit). The correlation coefficient of the obtained regression model is 0.97.This work has been partially supported by European Union through the ERANETMED (Euromediterranean Cooperation through ERANET joint activities and beyond) project ERANETMED3-227 SMARTWATIR by the Conselleria de Educación, Cultura y Deporte with the Subvenciones para la contratación de personal investigador en fase postdoctoral, grant number APOSTD/2019/04, and by the Cooperativa Agrícola Sant Bernat Coop.V.García, L.; Parra-Boronat, L.; Basterrechea-Chertudi, DA.; Jimenez, JM.; Rocher-Morant, J.; Parra-Boronat, M.; García-Navas, JL.... (2019). Quantifying the Production of Fruit-Bearing Trees Using Image Processing Techniques. IARIA XPS Press. 14-19. http://hdl.handle.net/10251/180619S141