Estudios sobre las Rubiáceas de México, LII

Abstract The Randia sepium is an extremely interesting species with its coriaceous medium-sized leaves glabrous and brilliant on both sides with 4–7 pairs of secondary nerves and terminal inflorescences, with medium-sized hirsute flowers and pubescent corolla lobes on both sides not having closely related taxon in the Mexican and Mesoamerican flora. All Randia species of these areas having coriaceous shiny leaves — e.g. R. cookii and R. chiapensis — are thorny small-leaved, nerveless, small-flowered ones with small glabrous, axillary or terminal solitary flowers. It is notable for its use, since it is applied as living fence in Chiapas (Mexico)

Estudios sobre las Rubiáceas de México, XLIX

Abstract The new Arachnothryx species collected in Veracruz is a vicarious one of the next related Arachnothryx secundiflora (B. L. Rob.) Borhidi of Oaxaca, Tabasco and Chiapas, which differs in having sessile bractless cymes. Another closely related species A. linguiloba Borhidi et Diego Pérez of Guerrero differs in size and pubescence of stipules and leaves and the size and shape of the flowers. This paper presents also a short note about the generic delimitation of Arachnothryx Planch. 1849 not Lorence 2012

From circular paths to elliptic orbits: A geometric approach to Kepler's motion

The hodograph, i.e. the path traced by a body in velocity space, was introduced by Hamilton in 1846 as an alternative for studying certain dynamical problems. The hodograph of the Kepler problem was then investigated and shown to be a circle, it was next used to investigate some other properties of the motion. We here propose a new method for tracing the hodograph and the corresponding configuration space orbit in Kepler's problem starting from the initial conditions given and trying to use no more than the methods of synthetic geometry in a sort of Newtonian approach. All of our geometric constructions require straight edge and compass only.Comment: 9 pages, 4 figure

Burn severity and regeneration in large forest fires: an analysis from Landsat time series

Revista oficial de la Asociación Española de Teledetección[EN] The main objective of this study is to take a close look at post-fire recovery patterns in forestry areas under different burn severity conditions. We also investigate the time that forestry ecosystems take to recover their pre-fire condition. In this context, this study analyses both the level of severity in Uncastillo forest wildfire (7.664ha), one of the greatest occurred in Spain in 1994, and the pattern of natural recovery in the following decades (until 2014) using annual Landsat time series (sensors TM&ETM+). Burn severity has been estimated by means of PROSPECT and GeoSAIL radiative transfer models following methodologies described in De Santis and Chuvieco (2009). On the other hand, recovery processes have been assessed from spectral profiles using the LandTrendr model (Landsat-based Detection of Trends in Disturbance and Recovery) (Kennedy et al., 2010). Results contribute to a further understanding of the post-fire evolution in forestry areas and to develop effective strategies for sustainable forest management.[ES] El objetivo de este estudio es contribuir a una mejor comprensión de los patrones de regeneración postincendio a partir de la severidad del fuego, así como estudiar el tiempo previsible que determinados ecosistemas forestales emplearán en recuperar su estado inicial. El estudio analiza el grado de severidad del incendio de Uncastillo de 1994 (7664 ha), uno de los mayores ocurridos en España en ese año, así como su dinámica de regeneración natural en las dos décadas siguientes (hasta 2014) mediante el empleo de series temporales de imágenes Landsat (sensores TM y ETM+). La estimación de la severidad post-incendio se ha basado en el uso de los modelos de transferencia radiativa PROSPECT y GeoSAIL, siguiendo la metodología propuesta por De Santis y Chuvieco (2009). Por su parte, los procesos de regeneración se han caracterizado mediante el empleo de trayectorias espectrales mediante el uso del modelo LandTrendr (Landsat-based Detection of Trends in Disturbance and Recovery) (Kennedy et al., 2010). Los resultados de este estudio contribuyen a una mayor comprensión de la dinámica general post-incendio de las áreas forestales y en último término permiten desarrollar estrategias efectivas para una gestión forestal sostenible.Ministerio de Economía y Competitividad. Proyecto Severidad y regeneración en grandes incendios forestales mediante teledetección y S.I.G (SERGISAT)(Ref. CGL2014-57013-C2-1-R–SERGISAT; CGL2014-57013-C2-2-R–SERGISATEste trabajo se ha desarrollado con la finan-ciación procedente del proyecto Severidad y regeneración en grandes incendios forestales mediante teledetección y S.I.G (SERGISAT)(Ref. CGL2014-57013-C2-1-R–SERGISAT; CGL2014-57013-C2-2-R–SERGISAT, Ministerio de Economía y Competitividad). Nuestro agra-decimiento también al Dr. Justin Braaten del Laboratory for Applications of Remote Sensing in Ecology de la Oregon State University, por su apoyo en el uso de LandTrendr.Martínez, S.; Chuvieco, E.; Aguado, I.; Salas, J. (2017). Severidad y regeneración en grandes incendios forestales: análisis a partir de series temporales de imágenes Landsat. Revista de Teledetección. (49):17-32. https://doi.org/10.4995/raet.2017.7182SWORD17324

Burn severity and regeneration in large forest fires: an analysis from Landsat time series

The main objective of this study is to take a close look at post-fire recovery patterns in forestry areas under different burn severity conditions. We also investigate the time that forestry ecosystems take to recover their pre-fire condition. In this context, this study analyses both the level of severity in Uncastillo forest wildfire (7.664ha), one of the greatest occurred in Spain in 1994, and the pattern of natural recovery in the following decades (until 2014) using annual Landsat time series (sensors TM&ETM+). Burn severity has been estimated by means of PROSPECT and GeoSAIL radiative transfer models following methodologies described in De Santis and Chuvieco (2009). On the other hand, recovery processes have been assessed from spectral profiles using the LandTrendr model (Landsat-based Detection of Trends in Disturbance and Recovery) (Kennedy et al., 2010). Results contribute to a further understanding of the post-fire evolution in forestry areas and to develop effective strategies for sustainable forest management

A useful form of the recurrence relation between relativistic atomic matrix elements of radial powers

Recently obtained recurrence formulae for relativistic hydrogenic radial matrix elements are cast in a simpler and perhaps more useful form. This is achieved with the help of a new relation between the $r^a$ and the $\beta r^b$ terms ($\beta$ is a $4\times 4$ Dirac matrix and $a, b$ are constants) in the atomic matrix elements.Comment: 7 pages, no figure

Usos del diseño metodológico cualitativo en artículos de acceso abierto de alto impacto en ciencias sociales

In this article we describe the uses of qualitative methodological designs in social science journals. A content descriptive analysis was performed. We reviewed 186 papers published in open-access journals indexed in the Scopus electronic database (Elsevier) during 2013-2015. Of the articles reviewed, 75% contained descriptions of the methodological designs utilized. In 51% of the articles qualitative designs were employed based on the type of study (ethnography, action research, grounded theory methodology, phenomenology, discourse analysis, among others); 37% of the articles used a design based on the specific guidelines for each approach; 11% based on the theoretical orientation of the authors (e.g., postpositivism, constructivism, critical theory, and others). We conclude that there are differences in conceptions of qualitative methodological designs in the corpus of articles reviewed.Las definiciones de diseño metodológico en la perspectiva cualitativa son variadas y sus diversos usos dejan entrever una multiplicidad de perspectivas. El presente trabajo tiene por objeto describir los usos del diseño metodológico cualitativo en artículos de ciencias sociales de alto impacto. Se realiza una revisión de 186 artículos de resultados de investigación y propuestas metodológicas, publicados en revistas open access indexadas en Scopus en el periodo 2013-2015. Los resultados muestran que el 75% de los artículos declara su diseño metodológico. El uso de este se clasificó en tres categorías: organización de la investigación, elección paradigmática y tipo de estudio. El 51% de los artículos utilizan diseño cualitativo basado en el tipo de estudio. Mientras tanto, la organización de la investigación (37%) y la elección paradigmática (11%) quedan en segundo lugar. Se concluye que los usos del diseño metodológico cualitativo se basa en supuestos teóricos y prácticas propias de la categoría definida como tipo de estudio. Esto puede facilitar la elección de un diseño cualitativo, sensible y flexible al contexto estudiado.In diesem Beitrag diskutieren wir die Darstellung qualitativer Designs in sozialwissenschaftlichen Open-Access-Zeitschriften vor dem Hintergrund einer deskriptiven Analyse, in die insgesamt 186 Artikel eingegangen sind, die zwischen 2013-2015 veröffentlicht und in Scopus, einer elektronischen Elsevier-Datenbank, indexiert wurden. 75% dieser Artikel enthielten Informationen über die jeweils genutzten Designs. In 51% hiervon wurden Designs ausgehend von der Art der jeweiligen Studie expliziert (z.B. Ethnografie, Handlungsforschung, Grounded-Theory-Methodologie, Phänomenologie oder Diskursanalyse). 37% der Artikel enthielten Beschreibungen engerer methodischer Herangehensweisen, und für 11% folgte die Beschreibung der Designs den epistemologischen/theoretischen Grundorientierungen der Autor/innen (Postpositivismus, Konstruktivismus, kritische Theorie usw.). Insoweit fanden sich für die untersuchte Datenbasis Unterschiede mit Blick auf die jeweils zugrunde gelegte Konzeption qualitativer Designs

Recurrence relation for relativistic atomic matrix elements

Recurrence formulae for arbitrary hydrogenic radial matrix elements are obtained in the Dirac form of relativistic quantum mechanics. Our approach is inspired on the relativistic extension of the second hypervirial method that has been succesfully employed to deduce an analogous relationship in non relativistic quantum mechanics. We obtain first the relativistic extension of the second hypervirial and then the relativistic recurrence relation. Furthermore, we use such relation to deduce relativistic versions of the Pasternack-Sternheimer rule and of the virial theorem.Comment: 10 pages, no figure