886 research outputs found
Evaluaci?n de la composici?n flor?stica, la estructura y la diversidad de tres bosques secos tropicales en el alto Magdalena, departamento del Tolima
80 p. Recurso Electr?nicoSe evalu? la composici?n flor?stica y estructural de tres bosques secos tropicales en el alto Magdalena, ubicados en el sur-oriente (bosque La Flor), centro (bosque El Neme) y norte (bosque la Zorra) del departamento del Tolima, por medio de tres parcelas permanentes de muestreo (PPM) de 0,25 has (50*50 m) cada una, una para cada bosque. Fueron medidos ?rboles, arbustos, lianas y palmas. La composici?n flor?stica, estructura horizontal, alfa-diversidad y beta-diversidad fue evaluada para todos los individuos con DN ? 1 cm., la estructura vertical fue analizada para los individuos arb?reos con DN ? a 5 cm. Se encontraron para el bosque La Flor 304 individuos representados por 62 especies pertenecientes a 26 familias bot?nicas, para La Zorra 1282 individuos representados por 60 especies pertenecientes a 35 familias, para El Neme 791 individuos, distribuidos en 21 especies pertenecientes a 12 familias bot?nicas, las especies de mayor peso ecol?gico fueron Handroanthus chrysanthus, Cordia gerascanthus y Platymiscium hebestachyum respectivamente. Los diagramas de perfil fueron graficados con los software AutoCAD 2017 y SketchUp 2017, resultando perfiles evidentemente contrastantes, la estructura vertical se analiz? por medio de diagramas de dispersi?n de copas, se visualizaron diferentes estratos relacionados con la complejidad de los respectivos bosques. Seg?n los ?ndices de Margalef, Shannon- Wiener y Simpson, el ecosistema m?s diverso es el bosque La Flor, seguido de la Zorra, El neme present? diversidad baja a media con dominancia de alta a media, seg?n Jaccard los 3 ecosistemas fueron ampliamente diferentes con menos del 6% de similaridad.
Palabras clave: Bosque Seco Tropical, Composici?n Flor?stica, Estructura Horizontal, Estructura Vertical, Alfa-Diversidad, Beta-Diversidad, Tolima, Alto Magdalena.The floristic and structural composition of three tropical dry forests in the upper Magdalena, located in the south-east (La Flor forest), center (El Neme forest) and north (La Zorra forest) of the department of Tolima, was evaluated by means of three permanent sampling plots (PPM) of 0.25 ha (50*50 m) each, one for each forest. Trees, shrubs, lianas and palms were measured. The floristic composition, horizontal structure, alpha-diversity and beta-diversity were evaluated for all individuals with DN ? 1 cm., the vertical structure was analyzed for arboreal individuals with DN ? at 5 cm. For La Flor forest, 304 individuals represented by 62 species belonging to 26 botanical families were found, for La Zorra 1282 individuals represented by 60 species belonging to 35 families, for El Neme 791 individuals distributed in 21 species belonging to 12 botanical families, the species with the highest ecological weight were Handroanthus chrysanthus, Cordia gerascanthus and Platymiscium hebestachyum respectively. The profile diagrams were plotted with AutoCAD 2017 and SketchUp 2017 software, resulting in contrasting profiles, the vertical structure was analyzed by means of crown scatter diagrams, different strata related to the complexity of the respective forests were visualized. According to the indices of Margalef, Shannon-Wiener and Simpson, the most diverse ecosystem is the La Flor forest, followed by the Zorra, El neme presented low to medium diversity with high to medium dominance, according to Jaccard the 3 ecosystems were widely different with less than 6% similarity.
Keywords: Tropical Dry Forest, Floristic Composition, Horizontal Structure, Vertical Structure, Alpha-Diversity, Beta-Diversity, Tolima, Alto Magdalena
Fenretinide induces mitochondrial ROS and inhibits the mitochondrial respiratory chain in neuroblastoma
Fenretinide induces apoptosis in neuroblastoma by induction of reactive oxygen species (ROS). In this study, we investigated the role of mitochondria in fenretinide-induced cytotoxicity and ROS production in six neuroblastoma cell lines. ROS induction by fenretinide was of mitochondrial origin, demonstrated by detection of superoxide with MitoSOX, the scavenging effect of the mitochondrial antioxidant MitoQ and reduced ROS production in cells without a functional mitochondrial respiratory chain (Rho zero cells). In digitonin-permeabilized cells, a fenretinide concentration-dependent decrease in ATP synthesis and substrate oxidation was observed, reflecting inhibition of the mitochondrial respiratory chain. However, inhibition of the mitochondrial respiratory chain was not required for ROS production. Co-incubation of fenretinide with inhibitors of different complexes of the respiratory chain suggested that fenretinide-induced ROS production occurred via complex II. The cytotoxicity of fenretinide was exerted through the generation of mitochondrial ROS and, at higher concentrations, also through inhibition of the mitochondrial respiratory chain
Fuentes digitales: un estudio de caso sobre la recuperación de la Memoria Histórica en España en Twitter
The incorporation of digital sources from online social media into historical research brings great opportunities, although it is not without technological challenges. The huge amount of information that can be obtained from these platforms obliges us to resort to the use of quantitative methodologies in which algorithms have special relevance, especially regarding network analysis and data mining. The Recovery of Historical Memory in Spain on the social network Twitter will be analysed in this article. An open-code tool called T-Hoarder was used; it is based on objectivity, transparency and knowledge-sharing. It has been in use since 2012.La incorporaciĂłn de fuentes digitales procedentes de las redes sociales on-line a la investigaciĂłn histĂłrica aporta grandes oportunidades aunque no estĂĄ exenta de retos tecnolĂłgicos. La ingente informaciĂłn que se puede obtener de estas plataformas aboca sin remedio al uso de metodologĂas cuantitativas en las que los algoritmos adquieren especial relevancia, especialmente en el anĂĄlisis de redes y la minerĂa de datos. En este artĂculo se analizarĂĄ RecuperaciĂłn de la Memoria HistĂłrica en España en la red social Twitter. Se aplicarĂĄ una metodologĂa denominada T-Hoarder_kit, de cĂłdigo abierto, usada desde el año 2012, que cumple con los requisitos de objetividad, transparencia y comparticiĂłn de conocimientos
Biodiversity of Fusarium species in Mexico associated with ear rot in maize, and their identification using a phylogenetic approach
Fusariumproliferatum, F. subglutinans, and F. verticillioides are known causes of ear and kernel rot in maize worldwide. In Mexico, only F. verticillioides and F. subglutinans, have been reported previously as causal agents of this disease. However, Fusarium isolates with different morphological characteristics to the species that are known to cause this disease were obtained in the Highland-Valley region of this country from symptomatic and symptomless ears of native and commercial maize genotypes. Moreover, while the morphological studies were not sufficient to identify the correct taxonomic position at the species level, analyses based in the Internal Transcribed Spacer region and the Nuclear Large Subunit Ribosomal partial sequences allowed for the identification of F. subglutinans, F. solani, and F. verticillioides, as well as four species (F. chlamydosporum, F. napiforme, F. poae, and F. pseudonygamai) that had not previously been reported to be associated with ear rot. In addition, F. napiforme and F. solani were absent from symptomless kernels. Phylogenetic analysis showed genetic changes in F. napiforme, and F. pseudonygamai isolates because they were not true clones, and probably constitute separate sibling species. The results of this study suggest that the biodiversity of Fusarium species involved in ear rot in Mexico is greater than that reported previously in other places in the world. This new knowledge will permit a better understanding of the relationship between all the species involved in ear rot disease and their relationship with maize
The subpopulation pattern of eel sperm is affected by post-activation time, hormonal treatment and thermal regime
[EN] There has been a marked reduction in natural stocks of eels (genus Anguilla) over the past 60 years, and the culture of eels is still based on the capture of very large quantities of juveniles. It is necessary to close the life cycle in captivity in order to ease the pressure on wild populations. The aims of the present study were to evaluate sperm subpopulations (through cluster analysis of computer-aided sperm analysis data) in the European eel (Anguilla anguilla) and to assess the effects of motility acquisition time after activation (i.e. at 30, 60 and 90 s), the thermal regimen (i.e. 10 degrees C (T10) or 15 degrees C (T15) and up to 20 degrees C, or constant at 20 degrees C (T20)) and hormonal treatments (i.e. human chorionic gonadotropin (hCG), recombinant (r) hCG or pregnant mare serum gonadotropin (PMSG)) on these subpopulations. In all cases, we obtained three subpopulations of spermatozoa: low velocity and linear (S1); high velocity with low linearity (S2); and high velocity and linear (S3; considered high quality). Total motility and S1 were affected by acquisition time; thus, 30 s is recommended as the standard time for motility acquisition. When eels were kept at 20 degrees C (T20), motility data fitted quadratic models, with the highest motility and proportion of S3 between Weeks 8 and 12 after the first injection. Lower temperatures (T10, T15) delayed spermiation and the obtaining of high-quality spermatozoa (S3), but did not seem to alter the spermiation process (similar subpopulation pattern). Conversely, the hormonal treatments altered both the dynamics of the subpopulation pattern and the onset of spermiation (with PMSG delaying it). Total motility and the yield of S3 with the widely used hCG treatment varied throughout the spermiation period. However, using rhCG allowed us to obtain high-quality and constant motility for most of the study (Weeks 7-20), and the S3 yield was also higher overall (61.8 +/- 1.3%; mean +/- s.e.m.) and more stable over time than the other hormonal treatments (averaging 53.0 +/- 1.4%). Using T20 and rhCG would be more economical and practical, allowing us to obtain a higher number of S3 spermatozoa over an extended time.This study was funded by the European Community's 7th Framework Program under the Theme 2 'Food, Agriculture and Fisheries, and Bio-technology', grant agreement no. 245257 (PRO-EEL) and Generalitat Valenciana (ACOMP/2012/086). VG and MCV have predoctoral grants from the Spanish Ministry of Economy and Competitiveness (AGL2010-16009) and Universitat Politecnica de Valencia (UPV) PAID Program (2011-S2-02-6521), respectively. DSP was supported by a contract cofinanced by Ministry of Science and Innovation (MICINN) and UPV (PTA2011-4948-I). FM-P was supported by the Ramon y Cajal program (MICINN, RYC-2008-02560).Gallego Albiach, V.; Vilchez Olivencia, MC.; Peñaranda, D.; Pérez Igualada, LM.; Herraez, MP.; Asturiano Nemesio, JF.; Martinez-Pastor, F. (2015). The subpopulation pattern of eel sperm is affected by post-activation time, hormonal treatment and thermal regime. Reproduction, Fertility and Development. 27(3):529-543. https://doi.org/10.1071/RD13198S52954327
Observational and Physical Classification of Supernovae
This chapter describes the current classification scheme of supernovae (SNe).
This scheme has evolved over many decades and now includes numerous SN Types
and sub-types. Many of these are universally recognized, while there are
controversies regarding the definitions, membership and even the names of some
sub-classes; we will try to review here the commonly-used nomenclature, noting
the main variants when possible. SN Types are defined according to
observational properties; mostly visible-light spectra near maximum light, as
well as according to their photometric properties. However, a long-term goal of
SN classification is to associate observationally-defined classes with specific
physical explosive phenomena. We show here that this aspiration is now finally
coming to fruition, and we establish the SN classification scheme upon direct
observational evidence connecting SN groups with specific progenitor stars.
Observationally, the broad class of Type II SNe contains objects showing strong
spectroscopic signatures of hydrogen, while objects lacking such signatures are
of Type I, which is further divided to numerous subclasses. Recently a class of
super-luminous SNe (SLSNe, typically 10 times more luminous than standard
events) has been identified, and it is discussed. We end this chapter by
briefly describing a proposed alternative classification scheme that is
inspired by the stellar classification system. This system presents our
emerging physical understanding of SN explosions, while clearly separating
robust observational properties from physical inferences that can be debated.
This new system is quantitative, and naturally deals with events distributed
along a continuum, rather than being strictly divided into discrete classes.
Thus, it may be more suitable to the coming era where SN numbers will quickly
expand from a few thousands to millions of events.Comment: Extended final draft of a chapter in the "SN Handbook". Comments most
welcom
Natural occurrence of the Fusarium solani on Tityus stigmurus (Thorell, 1876) (Scorpiones: Buthidae)
Safety of aromatase inhibitors in the adjuvant setting
The third-generation aromatase inhibitors (AIs) letrozole, anastrozole, and exemestane are replacing tamoxifen as adjuvant therapy in most postmenopausal women with early breast cancer. Although AIs have demonstrated superior efficacy and better overall safety compared with tamoxifen in randomized controlled trials, they may not provide the cardioprotective effects of tamoxifen, and bone loss may be a concern with their long-term adjuvant use. Patients require regular bone mineral density monitoring, and prophylactic bisphosphonates are being evaluated to determine whether they may protect long-term bone health. AIs decrease the risks of thromboembolic and cerebrovascular events compared with tamoxifen, and the overall rate of cardiovascular events in patients treated with AIs is within the range seen in age-matched, non-breast-cancer populations. AIs are also associated with a lower incidence of endometrial cancer and fewer vaginal bleeding/discharge events than tamoxifen. Compared with tamoxifen, the incidence of hot flashes is lower with anastrozole and letrozole but may be higher with exemestane. Generally, adverse events with AIs are predictable and manageable, whereas tamoxifen may be associated with life-threatening events in a minority of patients. Overall, the benefits of AIs over tamoxifen are achieved without compromising overall quality of life
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
Data from the Pierre Auger Observatory are analyzed to search for
anisotropies near the direction of the Galactic Centre at EeV energies. The
exposure of the surface array in this part of the sky is already significantly
larger than that of the fore-runner experiments. Our results do not support
previous findings of localized excesses in the AGASA and SUGAR data. We set an
upper bound on a point-like flux of cosmic rays arriving from the Galactic
Centre which excludes several scenarios predicting sources of EeV neutrons from
Sagittarius . Also the events detected simultaneously by the surface and
fluorescence detectors (the `hybrid' data set), which have better pointing
accuracy but are less numerous than those of the surface array alone, do not
show any significant localized excess from this direction.Comment: Matches published versio
Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
Atmospheric parameters, such as pressure (P), temperature (T) and density,
affect the development of extensive air showers initiated by energetic cosmic
rays. We have studied the impact of atmospheric variations on extensive air
showers by means of the surface detector of the Pierre Auger Observatory. The
rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find
that the observed behaviour is explained by a model including the effects
associated with the variations of pressure and density. The former affects the
longitudinal development of air showers while the latter influences the Moliere
radius and hence the lateral distribution of the shower particles. The model is
validated with full simulations of extensive air showers using atmospheric
profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle
Physic
- âŠ