Estimación de la estructura foliar en masas forestales: Fundamentos teóricos y análisis de la coherencia y fiabilidad de las mediciones mediante la aplicación informática TDL 2.0

In this paper, metodological basis for obtaining leaf area index and mean leaf inclination angle are presented. Also an application program (TDL 2.0) for estimating these parameters is presented. It makes use of data obtained from LI-COR LAI-2000 measurements, evaluates data reliability and coherence, and shows partial results on the screen for a visual assessment by the user. At last, differences with the C2000 utility are highlighted.Se exponen los fundamentos y la metodología de estimación del índice de área foliar y del ángulo medio foliar a partir de medidas realizadas con sensores ópticos como el LAI-2000. Asimismo se presenta una aplicación informática denominada TDL 2.0 (desarrollada por el autor) que permite estimar los citados parámetros de la estructura foliar a partir de medidas realizadas con el mencionado equipo. Además el TDL lleva a cabo una valoración de la coherencia y fiabilidad de los datos y muestra en pantalla algunos resultados parciales, que permiten una valoración visual de los mismos. También se exponen las diferencias con el programa C2000

Cationic exchange in nanosized ZnFe2O4 spinel revealed by experimental and simulated near-edge absorption structure

The non-equilibrium cation site occupancy in nanosized zinc ferrites (6-13 nm) with different degree of inversion (0.2 to 0.4) was investigated using Fe and Zn K-edge x-ray absorption spectroscopy XANES and EXAFS, and magnetic measurements. The very good agreement between experimental and ab-initio calculations on the Zn K-edge XANES region clearly show the large Zn2+(A)--Zn2+[B] transference that takes place in addition to the well-identified Fe3+[B]--Fe3+(A) one, without altering the long-range structural order. XANES spectra features as a function of the spinel inversion were shown to depend on the configuration of the ligand shells surrounding the absorbing atom. This XANES approach provides a direct way to sense cationic inversion in these spinel compounds. We also demonstrated that a mechanical crystallization takes place on nanocrystalline spinel that causes an increase of both grain and magnetic sizes and, simultaneously, generates a significant augment of the inversion.Comment: 5 pages, 5 eps figures, uses revtex4, corrected table

Estado de excepción en el discurso securitario: reflexiones en torno a la violencia de Estado

En este documento intentaremos pensar la producción del discurso securitario y sus argumentos de autolegitimación a partir de un recorrido que va desde Hobbes hasta enfoques contemporáneos enfocados en la configuración acéfala del poder. Estos últimos rebasan en parte las terminologías propias de las teorías de la soberanía, abriendo un espacio de excepción extrajurídico incorporado por la ley, en donde la violencia de Estado parece ser la instauración constante de su propia conservación. La propuesta de este artículo es hacer una lectura teórica que nos permita re-pensar de manera crítica a procesos inscritos en las técnicas de gubernamentalidad del Chile contemporáneo

Mechanistic studies of the palladium-catalyzed S,O-ligand promoted C-H olefination of aromatic compounds

Pd-catalyzed C-H functionalization reactions of non-directed substrates have recently emerged as an attractive alternative to the use of directing groups. Key to the success of these transformations has been the discovery of new ligands capable of increasing both the reactivity of the inert C-H bond and the selectivity of the process. Among them, a new type of S,O-ligand has been shown to be highly efficient in promoting a variety of Pd-catalyzed C-H olefination reactions of non-directed arenes. Despite the success of this type of S,O-ligand, its role in the C-H functionalization processes is unknown. Herein, we describe a detailed mechanistic study focused on elucidating the role of the S,O-ligand in the Pd-catalyzed C-H olefination of non-directed arenes. For this purpose, several mechanistic tools, including isolation and characterization of reactive intermediates, NMR and kinetic studies, isotope effects and DFT calculations have been employed. The data from these experiments suggest that the C-H activation is the rate-determining step in both cases with and without the S,O-ligand. Furthermore, the results indicate that the S,O-ligand triggers the formation of more reactive Pd cationic species, which explains the observed acceleration of the reaction. Together, these studies shed light on the role of the S,O-ligand in promoting Pd-catalyzed C-H functionalization reactions.</p

Quantification of the influence of the C, Cr and P contents on the permeability of hydrogen through Fe alloys

[EN] Ferritic-martensitic steels are candidate materials for blanket structural components of future thermonuclear fusion reactors. However, the tritium inventory that can be retained in different components of the reactor and its ability to migrate through the walls of any material may affect the correct operation of any fusion device. Therefore, the permeability of hydrogen isotopes through ferritic-martensitic steels, which depends on its metallurgical composition, becomes a key issue. The European Fusion Development Agreement (EFDA) supplied 9 Fe alloys with controlled chemical alloying element contents and microstructure. The main alloying elements were C, Cr and P and they appeared in various concentrations in the 9 alloys. They were experimentally analyzed by means of the gas evolution permeation technique with temperatures ranging from 423 K to 823 K and for high purity hydrogen loading pressures ranging from 5.0 x 102 Pa to 1.5 x 105 Pa. The transport regime turned out to be diffusive and it was studied in depth, so that the permeability of each alloy was characterized by an Arrhenius-type regression for the aforementioned temperature range. This work summarizes all the experimental measurements carried out for the permeability of hydrogen through the 9 alloys. It provides a quantification of the influence of the composition of the alloy on this transport parameter, posing different mathematical expressions for the variation of the permeability as a function of the contents of C, Cr and P.This work has been carried out in the framework of research projects funded by the Spanish Ministry of Science and Innovation (MEC08/98) , the University of the Basque Country (UPV/EHU-EHU08-34) and the European Fusion Development Agreement (EFDA MAT-REMEV) . The authors would also like to thank the FEMaS Coordinated Action project for the support in knowledge exchange among different research groups and Pilar Fernandez from CIEMAT for the preparation of the tested samples

Estimación de la altura dominante de la masa partir de la “altura dominante de parcela”. Ventajas frente a la altura dominante de Assman

Assman top height is a parameter whose measurement or estimation is tiring in the practice and presents some inconveniences from a stadistical point of view which lessens efectiviness. Considering it’s a dasometric parameter widely used in Spain and with important silvicultural implications, we consider it suitable to look for alternatives which solve the faults of the aforesaid top height. In this paper we propose, as an alternative, the criterion used by the English management tables that not only consider with accuracy the top height concept but is more operative from a practical point of view and easy to handle from an stadistical one. In this management table a stand top height is defined as an average value of a variable number of top height trees. A top height tree is defined as the thickest tree height in a 100 m2 plot. Depending on the heterogeneity and extension of the stand more or less plots will be necessary to estimate its top height with a determined accuracy.La altura dominante de Assman es un parámetro cuya medición o estimación resulta laboriosa en la práctica, y presenta algunos inconvenientes desde el punto de vista estadístico que le restan operatividad. Teniendo en cuenta que se trata de un parámetro dasométrico de uso muy generalizado en España y con importantes implicaciones selvícolas, se considera adecuado buscar alternativas que solventen las pegas de la citada altura dominante. Como alternativa, en este trabajo se propone adoptar el criterio que utilizan las tablas de producción inglesas (Hamilton et al., 1981) ya que además de atender con bastante fidelidad al concepto de altura dominante, es más operativo desde el punto de vista práctico y fácil de manejar desde el punto de vista estadístico. En las citadas tablas de producción la altura dominante de una masa se define como el valor medio de un número variable de “alturas dominantes de parcela”. Una “altura dominante de parcela” se define como la altura del árbol más grueso en una parcela de 100 m2. Dependiendo de la heterogeneidad y extensión de la masa, serán necesarias más o menos parcelas para estimar su altura dominante con una determinada precisión

Seismic activity and an anomalous fumarolic chemical composition due to seal effect in the volcanic system of Deception Island (Antarctica)

In this communication, the genesis of great anomalous seismic activity registered during austral summer 2003/2004 on Deception Island (Antarctica) is discussed, and related with changes on the chemical composition of fumarolic gases and vent deposits. Here we present a comparative analysis performed to explain this activity. We propose a possible parcial seal of the microfracture system. This effect allows an increase on pressure follow by reopening of microfractures, resulting on a sequence of seismic events and changes on the chemical composition of fumarolic emissions.Fil:Caselli, A.T. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Bengoa, C.L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Agusto, M.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Influenza vaccination among multiple sclerosis patients during the COVID-19 pandemic

In the context of the COVID-19 pandemic, the co-circulation of influenza and SARS-CoV-2 viruses may have severe complications for vulnerable populations. For this reason, the World Health Organization pointed to the 2020–2021 anti-influenza campaign as being of special relevance. Our aim was to assess the 2020–2021 influenza vaccination coverage, and its associated factors, among patients in a Spanish multiple sclerosis (MS) unit. A cross–sectional study was conducted. People attending the MS unit of the Clinical Hospital of Zaragoza during 2020 were included. Variables were obtained by reviewing records. Associations with 2020–2021 influenza vaccination were analyzed using bivariate analysis and a multiple logistic regression model. A total of 302 patients were studied; 62.6% were women, whose mean age (standard deviation) was 47.3 (11.5) years. The 2020–2021 influenza vaccination coverage was 55.3% (59.8% in women and 47.8% in men). A total of 89.7% had at least one other indication for vaccination (e.g., immunosuppressive treatment in 225 patients). The variables associated with getting vaccinated were being female (adjusted odds ratio (95% confidence interval) (aOR (95%CI) = 2.12 (1.12–3.99)), having received the 2019–2020 influenza vaccine (aOR (95%CI) = 31.82 (14.71–68.86)) and being born in Spain (aOR (95%CI) = 12.91 (1.07–156.28)). Coverage is moderate compared to other countries. It is necessary to develop strategies to improve it, especially in men and those born outside Spain

Effectiveness of the Lapidus plate system in foot surgery: A PRISMA compliant systematic review

Lapidus arthrodesis is an established standard procedure to correct various foot surgery problems and hallux limitus, hypermobility of the first ray, hallux abductus valgus, and symptomatic lesser metatarsal. After decades, many fixation methods in the orthopaedic surgery industry have been developed for decreasing complications and improving this technique. The aim of this PRISMA compliant systematic review is to analyse the effectiveness of several lapidus plate systems in foot surgery. We have carried out the first systematic review of the relevant published literature so as to systematically evaluate the scientific knowledge available now on this association, assigning predefined eligibility criteria. Fourteen studies were selected which had an overall of 738 cases. The first tarsal metatarsal joint and hallux valgus were treated by the application of different types of Lapidus plate system. The optimal level of the fixation in these procedures is related with the type and system insertion place of the plate with or without screw in each specific foot disease. There is an insufficient number of studies about the effectiveness of the different types of Lapidus plate system in foot surgery, and there is a need to increase outcomes knowledge on the level of the fixation, sort of the system, and insert place in foot surgery

Structural interaction between bone and implants due to arthroplasty of the first metatarsophalangeal joint

Background: Currently, the metatarsophalangeal joint replacement through a restorative arthroplasty, where implants are used, is a viable invasive surgical medical procedure in the treatment of severe cases of osteoarthritis in this joint, better known as hallux rigidus. However, few things are known about the postoperative complications that implants can cause on the joint, like Swanson and Tornier implants.Research in this field can provide a valuable information that would help the specialist surgeon in the decision-making during the selection of the more suitable joint implant in each patient, as well as the redesign of the devices, to make them more efficient, durable and biocompatible with the human body. Methods: The aim of this work is to perform a structural biomechanical analysis of a restorative arthroplasty of the first metatarsophalangeal joint, and to analyze the interaction between bone and medical grade silicone implants. For that, a simulation of a foot with Swanson and Tornier joint implants were performed to evaluate the stress/strain distribution during a critical stage (toe-off). Results and conclusions: Principal stresses obtained for the first metatarsal with both implants suggest that failure is induced in this bone because, values exceed (up to 136.84% for Swanson model) the tensile strength reported for phalange trabecular bone, which may be related to osteolysis. Stress and strain values obtained in this work suggest that arthroplasty surgery with Swanson implant is more likely to cause postoperative complications versus Tornier implant