1,900 research outputs found
Graded Lie algebras and q-commutative and r-associative parameters
We study graded Lie algebras whose transformation parameters are graded q-commutativive and r-associative. We study first some graded algebras over a field, with no zero divisors at the level of monomials in their graded algebra generators. These generators are q-commutative and r-associative. We address the cohomology of the q-function and r-functions, in particular we study quaternions and octonions. We then define algebras whose transformation parameters are q-commutative and r-associative. We address a generalization of a theorem by Scheunert on its relation to Lie (super)algebras. We show finally that for the cases studied by Scheunert there is always a real and faithful transformation parameter basis with the required q-commutativity. We use this basis to perform a transformation on the graded Lie algebra that relates it to a plain Lie (super)algebra while respecting the self-adjoint character of generators and preserving the group grading. Keywords: Graded Lie (super)algebras, Color Lie (super)algebras, noncommutative algebras, nonassociative algebras, cohomology of deformation parameters, perfect algebra. AMS-MSC: 17B70, 17B75, 22E60, 17A99, 17D99, 13D03, 20J06
Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy
Stripe domains are studied in perpendicular magnetic anisotropy films
nanostructured with a periodic thickness modulation that induces the lateral
modulation of both stripe periods and inplane magnetization. The resulting
system is the 2D equivalent of a strained superlattice with properties
controlled by interfacial misfit strain within the magnetic stripe structure
and shape anisotropy. This allows us to observe, experimentally for the first
time, the continuous structural transformation of a grain boundary in this 2D
magnetic crystal in the whole angular range. The magnetization reversal process
can be tailored through the effect of misfit strain due to the coupling between
disclinations in the magnetic stripe pattern and domain walls in the in-plane
magnetization configuration
EPITRAGUS AURULENTUS (KIRSCH) (COLEOPTERA: TENEBRIONIDAE): A NEW RECORD AND REPORT FOR PUERTO RICO
EPITRAGUS AURULENTUS (KIRSCH) (COLEOPTERA: TENEBRIONIDAE): A NEW RECORD AND REPORT FOR PUERTO RIC
Crossed-ratchet effects and domain wall geometrical pinning
The motion of a domain wall in a two dimensional medium is studied taking
into account the internal elastic degrees of freedom of the wall and
geometrical pinning produced both by holes and sample boundaries. This study is
used to analyze the geometrical conditions needed for optimizing crossed
ratchet effects in periodic rectangular arrays of asymmetric holes, recently
observed experimentally in patterned ferromagnetic films. Geometrical
calculations and numerical simulations have been used to obtain the anisotropic
critical fields for depinning flat and kinked walls in rectangular arrays of
triangles. The aim is to show with a generic elastic model for interfaces how
to build a rectifier able to display crossed ratchet effects or effective
potential landscapes for controlling the motion of interfaces or invasion
fronts.Comment: 13 pages, 18 figure
Global phylogeography and evolution of chelonid fibropapilloma-associated herpesvirus
A global phylogeny for chelonid fibropapilloma-associated herpesvirus (CFPHV), the most likely aetiological agent of fibropapillomatosis (FP) in sea turtles, was inferred, using dated sequences, through Bayesian Markov chain Monte Carlo analysis and used to estimate the virus evolutionary rate independent of the evolution of the host, and to resolve the phylogenetic positions of new haplotypes from Puerto Rico and the Gulf of Guinea. Four phylogeographical groups were identified: eastern Pacific, western Atlantic/eastern Caribbean, mid-west Pacific and Atlantic. The latter comprises the Gulf of Guinea and Puerto Rico, suggesting recent virus gene flow between these two regions. One virus haplotype from Florida remained elusive, representing either an independent lineage sharing a common ancestor with all other identified virus variants or an Atlantic representative of the lineage giving rise to the eastern Pacific group. The virus evolutionary rate ranged from 1.62x10(-4) to 2.22x10(-4) substitutions per site per year, which is much faster than what is expected for a herpesvirus. The mean time for the most recent common ancestor of the modern virus variants was estimated at 192.90-429.71 years ago, which, although more recent than previous estimates, still supports an interpretation that the global FP pandemic is not the result of a recent acquisition of a virulence mutation(s). The phylogeographical pattern obtained seems partially to reflect sea turtle movements, whereas altered environments appear to be implicated in current FP outbreaks and in the modern evolutionary history of CFPHV.DNER-PR; US NMFS (NMFS-NOAA) [NA08NMF4720436]; US-Fish and Wildlife Service (USFWS); Sociedad Chelonia; WIDECAST; US Environmental Protection Agency (US-EPA); Lisbon Oceanarium, Portugal; Interdisciplinary Research Center for Animal Health of the Faculty of Veterinary Medicine of the Technical University of Lisbon (FMV/TUL)info:eu-repo/semantics/publishedVersio
Conocimiento y poder: la asimetría de intereses de los médicos colombianos y de Rockefeller en la construcción del concepto de fiebre amarilla selvática, 1907-1938
Este estudio examina las asimetrías entre los diferentes intereses de los funcionarios y médicos que trabajaron para la Fundación Rockefeller y sus contrapartes colombianas en el desarrollo y consolidación del concepto de 'fiebre amarilla de la selva', a diferencia de la conocida forma urbana de fiebre amarilla. Exploramos las respuestas de investigación a una variedad de brotes de enfermedades en Colombia en el contexto de las campañas de Rockefeller contra la fiebre amarilla, desde la descripción inicial de Roberto Franco de la 'fiebre amarilla de los bosques' en 1907 hasta la consolidación del concepto. de 'fiebre amarilla de la jungla' de Fred Soper en 1938.This study examines the asymmetries among the different interests of officials and medical doctors who worked for the Rockefeller Foundation and their Colombian counterparts in the development and consolidation of the concept of “jungle yellow fever,” as distinguished from the known urban form ofyellow fever. We explore the research responses to a variety of disease outbreaks in Colombia in the context of the Rockefeller campaigns against yellow fever, from the time of Roberto Franco’s initial description of “yellow fever of the forests” in 1907 until the consolidation of the concept of “jungle yellow fever” by Fred Soper in 1938.Cette étude examine las divergencias de interes parmi les fonction-naires et les meddecins qui ont travaillé pour la Fondation Rockefeller et sa filiale colombienne dans le développement et la consolidation du concept de «la fièvre jaune selvatique», qui diffère de la forme connue de fièvre jaune urbaine. Nous explorons les réponses de recherche à une variété d'irruptions de maladie en Colombie dans le contextte des campagnes de la Fondation Rockefeller con-tre la fìèvre jaune depuis la description initle de la «fièvre jaune des forêts» de Roberto Franco en 1907 jusqu ' à la consolidación del concepto de fièvre jaune sel-vatique por Fred Soper en 1938
Osmium- And Iridium-Promoted C-H Bond Activation of 2, 2'-Bipyridines and Related Heterocycles: Kinetic and Thermodynamic Preferences
The d2-hexahydride complex OsH6(PiPr3)2 (1) promotes the activation of C-H bonds of 2, 2'-bipyridines and related heterocycles. The study of the same reactions with the deuteride counterpart OsD6(PiPr3)2 (1-d) reveals that the activation of the C-H bonds situated in the sterically less hindered positions is kinetically preferred. However, the isolated products are the result of the thermodynamic control of the reactions. Thus, reactions of 1 with 2, 2'-bipyridine, 6-phenyl-2, 2'-bipyridine, and 6-methyl-2, 2'-bipyridine give the "rollover cyclometalation" products OsH3{¿2-C, N-[C5(R)H2N-py]}(PiPr3)2 (R = H (2), Ph (3), Me (4)), whereas 3, 5-dimethyl-6-phenyl-2, 2'-bipyridine affords OsH2{¿3-C, N, C-[C5H3N-(Me)2py-C5H4]}(PiPr3)2 (5), containing a dianionic C, N, C-pincer ligand. The behavior of substrates pyridyl-benzimidazolium and -imidazolium is similar. Reaction of 1 with 3-methyl-1-(6-phenylpyridin-2-yl)-1H-benzimidazolium tetrafluoroborate leads to OsH3{¿2-C, C-[MeBzim-C5(Ph)H2N]}(PiPr3)2 (6), bearing an anionic Cpy, CNHC-chelate. On the other hand, 3-methyl-1-(6-phenylpyridin-2-yl)-1H-imidazolium tetrafluoroborate yields [OsH2{¿3-C, N, C-(MeIm-py-C6H4)}(PiPr3)2]BF4 (7), containing a monoanionic C, N, C-pincer with a NHC-unit coordinated in an abnormal fashion. The reactivity pattern of these substrates is also observed with the d4-iridium-pentahydride IrH5(PiPr3)2 (8), which has generated IrH2{¿2-C, N-[C5(R)H2N-py]}(PiPr3)2 (R = H, (9), Ph (10)) and IrH{¿3-C, N, C-[C5H3N-(Me2)py-C5H4]}(PiPr3)2 (11). The osmium(IV)-carbon bonds display a higher degree of covalency than the iridium(III)-carbon bonds. In contrast to 2, the metalated carbon atom of 9 undergoes the addition of a proton of methanol to give [IrH2{¿2-N, N-(bipy)}(PiPr3)2]BF4 (12)
Un marco conceptual y analítico para estimar la integridad ecológica a escala de paisaje
A conceptual and analytical framework to assess ecological integrity at a landscape level. A concep tual and methodological approach for the ecological integrity analysis at landscape level is presented. The aim is providing a tool for land planning and nature conservation. With this purpose the meaning of integrity and related concepts are discussed, and a model to evaluate landscape integrity by a comprehensive scheme is proposed. The first index is based in metrics of landscape ecology theory (connectivity, cover of both conservation areas and human managed land, etc.) to evaluate the different ecosystem fragments pattern. The second one, an ecosystems integrity index, is focused to evaluate remnants with a structure close to maturity and evaluates the mathematical distance to a reference hypothetical composition. Finally, the agricultural area is evaluated by a coherence index, with emphasis in ecological processes but also including the natural structures with conservation functions. These indexes are combined in a model that facilitates the joint consideration of their values and the comparison with theoretical scenarios. The model allows us to develop a concurrent management of relevant variables that usually are associated to different environmental qualities. Because of its characteristics and the intermediate scale of application, the model constitutes an important tool for matching ecosystem integrity and land planning. Both are actions and concept and relevant for nature conservation and landscape management, but in general independently considered.El trabajo constituye una aproximación conceptual y metodológica para el análisis de la integridad ecológica, como instrumento aplicable a la planificación del territorio y la conservación de la naturaleza a escala de paisaje. Con dicho fin se discuten las acepciones de integridad y conceptos próximos y se presenta un modelo de evaluación que considera la integridad del paisaje como resultado de la interacción de tres índices. El primero (integridad espacial) utiliza métricas de la ecología del paisaje (conectividad y cobertura de áreas naturales y áreas de uso humano) y evalúa la distribución de los fragmentos de los distintos tipos de ecosistemas existentes en el territorio. El segundo, un índice de integridad ecosistémica, se centra en los fragmentos con estructura más próxima a la madurez y valora su distancia numérica a ecosistemas de referencia. Por último, en el área sometida a usos agrícolas, se aplica un índice de coherencia ecológica de los usos del suelo que tiene en los elementos naturales con funciones de conservación. Estos índices son articulados mediante un modelo que facilita una visión simultánea de sus valores, así como su comparación con escenarios teóricos. El modelo permite manejar de forma simultánea variables relevantes que comúnmente se presentan como asociadas a aspectos diferentes de la calidad del entorno. Por sus características y escala intermedia de aplicación puede constituir una herramienta importante para enlazar conceptos y actuaciones, relevantes para la conservación de la naturaleza, pero que suelen manejarse por separado, en concreto la integridad ecosistémica y con la planificación del territorio
Pulmonary thromboembolism and alveolar hemorrhage as initial manifestations of systemic lupus erythematosus
Systemic lupus erythematosus (SLE) is an autoimmune disease that affects multiple organs. SLE can affect the lung, the pulmonary vasculature, and the pleura. A 38-year-old female with limb pain and ecchymosis who later developed pulmonary thromboembolism and alveolar hemorrhage is presented here. Clinical, imaging, laboratory, and histopathological evidence is presented. The patient met the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) criteria for SLE. Furthermore, the patient had a Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score of 35; thus, indicating severe disease. This case is an example of concomitant venous and arterial lung complications in an SLE patient
The Hazards of Monitoring Ecosystem Ocean Health in the Gulf of Mexico: A Mexican Perspective
Ecological services provided by the Gulf of Mexico constitute vital assets for the socioeconomic development of the USA, Mexico, and Cuba. This ecosystem houses vast biodiversity and significant fossil fuel reserves. However, its ecological stability and resilience have been jeopardized by anthropogenic disturbances. Massive oil spills (Ixtoc-I, 1979; Deepwater Horizon, 2010) caused severe environmental injuries and unveiled the vulnerability of coastal and deep-sea habitats. Baseline and monitoring studies are actions implemented by the Gulf stakeholders to cope with such disturbances. The 3-year monitoring program implemented by Mexico in 2010 to assess the environmental damage caused by the Deepwater Horizon (DWH) event confirmed the void of knowledge on the complexity of physical and biological processes susceptible of being altered by oil spills. Between the pelagic and benthic compartments, the latter proved to be a better option in establishing the baseline concentration and trends of oil compounds. Surficial sediments exhibited an increasing concentration trend of PAH, AH, and trace metals throughout the 3-year monitoring. The macroinfauna and selected biomarkers experienced interannual variability attributed to critical hydrocarbon and trace metal thresholds. Sediment toxicity bioassays added support to the distribution and potential sources of oil contaminants dispersed from the northern gulf toward Mexican waters
- …