Cosmological predictions from the Misner brane

Within the spirit of five-dimensional gravity in the Randall-Sundrum scenario, in this paper we consider cosmological and gravitational implications induced by forcing the spacetime metric to satisfy a Misner-like symmetry. We first show that in the resulting Misner-brane framework the Friedmann metric for a radiation dominated flat universe and the Schwarzschild or anti-de Sitter black holes metrics are exact solutions on the branes, but the model cannot accommodate any inflationary solution. The horizon and flatness problems can however be solved in Misner-brane cosmology by causal and noncausal communications through the extra dimension between distant regions which are outside the horizon. Based on a semiclassical approximation to the path-integral approach, we have calculated the quantum state of the Misner-brane universe and the quantum perturbations induced on its metric by brane propagation along the fifth direction. We have then considered testable predictions from our model. These include a scale-invariant spectrum of density perturbations whose amplitude can be naturally accommodated to the required value 10$^{-5}-10^{-6}$, and a power spectrum of CMB anisotropies whose acoustic peaks are at the same sky angles as those predicted by inflationary models, but having much smaller secondary-peak intensities. These predictions seem to be compatible with COBE and recent Boomerang and Maxima measurementsComment: 16 pages, RevTe

Datos sobre la alianza Corynephoro-Plantaginion radicatae Rivas Goday & Rivas-Martínez 1963 nom. invers. Rivas-Martinez 1975 en el sector Orensano-sanabriense

The poor, open, hard meadows are studied. They are formed by pulvinular species in supramediterranean level, with subhumid and humid ombroclimous. They are included in the alliance Corynephoro-Plantaginion radicatae Rivas Godoy O Rivas-Martínez 1963 nom. invers. Rivas-Martínez 1975. The association Diantho merinoi-Plantaginetum radicatae nova is described.Se estudian los pastizales duros, abiertos y pobres constituidos por especies vegetales pulvinulares del piso supramediterráneo de ombroclimas subhúmedo y húmedo del Sector Orensano-Sanabriense, incluibles en la alianza Corynephoro-Plantaginion radicatae RivasGoday Rivas-Martínez 1963 nom. invers. Rivas-Martínez 1975, describiéndose la asociación Diantho merinoi-Plantaginetum radicatae nova

Datos sobre la vegetación terofítica y nitrófila leonesa

In this paper, we describe two associations: Plantago loeflingii-Prolongoetum pectinatae nova y Minuartio hybridae-Saxifragetum tridactylitis nova (Tuberarietea guttatae Br.-Bl. 1952 em. Rivas-Martínez 1977); also we give some chorological,ecological and variability facts, about another the rophitic and nitrogenous communities already defined, and components of the vegetation of León.En el presente trabajo se describen dos asociaciones: Plantago loeflingii-Prolongoetum pectinatae nova y Minuartio hybridae-Saxifragetum tridactylitis nova (Tuberarietea guttatae Br. -Bl. 1952 em. Rivas-Martínez 1977), aportándose datos corológicos y ecológicos de otras comunidades terofiticas y nitrófilas descritas y que forman parte de la vegetación leonesa

De Plantis Legionensibus. Nota III

As following the former check—list notes on León area, twelve taxa are recorded by the firs time for this area.Como continuación de las anteriores notas florísticas, se complementa el catálogo provincial con una docena de táxones, resultado de diversas recolecciones botánicas efectuadas por distintas zonas del territorio leonés

Uses of Native Plant Species of a Communal Rangeland within ‘Sierra de Huautla’ Protected Area, México

Sustainability of communal rangelands has become a major concern at national and international levels because land use conflicts and associated social conflicts allows for over-utilization of selected species making a high pressure on them and given away their places to species with no use at all becoming lands degraded and unproductive. The objective of the study was to determine floristic composition and native plant uses by local peasants. The range surface is of 4262 ha, belongs to the communal land ‘El Limon’, in Tepalcingo, Morelos, Mexico, and it is within the Natural Reserve Area “Sierra de Huautla”. Native vegetation is mainly of deciduous shrubs, high temperatures year round and a rainy season of 4 months. Local peasants were surveyed on uses of the collected and previously identified plants. Number of species was 456, distributed in 266 and 76 botanical genders and families, respectively. Of the species identified 66, 22 and 12% had one, two or more than two uses according to local peasants. Among uses: 59% of the species were used as forage, 8% eatable, 7% firewood or ornamental, 6% medical herb, lumber or other use 4 %, construction material 3 % and for resin or handcraft 1%. The range showed a very high plant biodiversity, this feature allows for a high resiliency toward human activities

Census of HII regions in NGC 6754 derived with MUSE: Constraints on the metal mixing scale

We present a study of the HII regions in the galaxy NGC 6754 from a two pointing mosaic comprising 197,637 individual spectra, using Integral Field Spectrocopy (IFS) recently acquired with the MUSE instrument during its Science Verification program. The data cover the entire galaxy out to ~2 effective radii (re ), sampling its morphological structures with unprecedented spatial resolution for a wide-field IFU. A complete census of the H ii regions limited by the atmospheric seeing conditions was derived, comprising 396 individual ionized sources. This is one of the largest and most complete catalogue of H ii regions with spectroscopic information in a single galaxy. We use this catalogue to derive the radial abundance gradient in this SBb galaxy, finding a negative gradient with a slope consistent with the characteristic value for disk galaxies recently reported. The large number of H ii regions allow us to estimate the typical mixing scale-length (rmix ~0.4 re ), which sets strong constraints on the proposed mechanisms for metal mixing in disk galaxies, like radial movements associated with bars and spiral arms, when comparing with simulations. We found evidence for an azimuthal variation of the oxygen abundance, that may be related with the radial migration. These results illustrate the unique capabilities of MUSE for the study of the enrichment mechanisms in Local Universe galaxies.Comment: 13 pages, 7 Figurs, accepted for publishing in A&

Spectral fluorescence variation of pollen and spores from recent peat-forming plants

The fluorescence properties of spores and pollen grains examined under ultraviolet incident light are used to assess the maturity of sedimentary organic matter and may have other applications in relation to recent sediments, in areas such as paleoenvironmental research. In this study pollen grains and spores from 33 species common in peat ecosystems were mounted on a glass slide in accordance with standard palynologycal procedures for recent plants. The main objective of this work was to assess the variability of fluorescence spectra of pollens and spores within a single species or even within a single sample. A minimum of 10 spectra were recorded from each sample and were averaged to obtain a spectrum characteristic of each sample. Both the average scattering and the scattering in different spectral regions were calculated using the standard deviation (SD) and the coefficient of variation (CV). The effect of the preparation techniques was assessed on some samples of Ericaceae taxa. The results indicated similar spectra for alcohol-washed and distilled water-washed samples, whereas the application of an acetolysis solution caused an increase in intensity and a shift to longer wavelengths. The spectra corresponding to the Sphagnum spores had the lowest intensity of all the families studied and displayed their maxima at the lowest registered wavelengths. They often showed a peak in the red region of the spectra, causing a larger scatter in fluorescence in this region. This peak is probably the result of wax or cytoplasmic material attached to the exospore. A significant number of Ericaceae taxa had two fluorescing pollen populations: a blue one of high intensity and smaller size and a yellow-orange one of low intensity and larger size. This difference could be related to different degrees of maturity of the pollen grains. In the case of pollen grains of herbaceous, tree and bush plants the largest scatter was found in the tails of the spectra toward the blue and red regions. The decreasing trend of fluorescence intensity with the shift of the spectra toward red was not observed in the pollen and spores of fresh plants. A good correlation was found between the spectral maxima (λmax) and the red-green quotient (QR/G) regardless of the type of plant.Financial support from MICINN (CGL2009-13990-C02-01/02), MINECO (CGL2013-46458-C2-1-R) and a FPU fellowship from MEC for J. Urbanczyk are gratefully acknowledged.Peer reviewe

Adaptation of the colorimetric MTT assay for evaluating activity against Giardia duodenalis

Giardia duodenalis es un parásito protozoario flagelado cosmopolita con un amplio rango de hospedadores, incluyendo tanto animales domésticos como salvajes, así como al ser humano. Se reproduce en el intestino delgado ocasionando giardiosis, enfermedad caracterizada por producir diarrea, cólicos abdominales, pérdida de peso y malabsorción. El presente trabajo tiene como objetivo la estandarización del método colorimétrico del MTT (bromuro de 3-(4,5- dimetiltiazol-2-ilo)-2,5-difeniltetrazol) para la realización de ensayos de actividad in vitro frente a trofozoítos de G. duodenalis. El MTT ha demostrado ser útil en la determinación de productos activos frente a diversos biomodelos y un buen sustituto del recuento microscópico en la determinación de la viabilidad de los parásitos. Para adaptar este método a G. duodenalis se realizaron una serie de ensayos a fin de optimizar la prueba, empezando con la realización de curvas de crecimiento para observar el comportamiento de los cultivos de este protozoario. Además, se realizaron otros ensayos modificando ciertas variables como el inóculo inicial, la fase del cultivo o las concentraciones de reactivos, dando como resultado un protocolo efectivo estandarizado. Los resultados de este estudio pueden ser de gran utilidad para identificar compuestos con actividad frente a G. duodenalis.dengue, pero ¿cómo explicar la desatención de esa virosis por el conocimiento público en 2023?Giardia duodenalis is a cosmopolitan flagellated protozoan parasite with a wide range of hosts, including both domestic and wild animals, as well as humans. It reproduces in the small intestine causing giardiosis, a disease characterized by diarrhea, abdominal cramps, weight loss, and malabsorption. The aim of this study is to standardize the colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method for in vitro assays against G. duodenalis trophozoites. The MTT has been shown to be useful in determining active products against various biomodels and a good substitute for microscopic counting in determining parasite viability. To adapt this method to G. duodenalis, a series of assays were performed to optimize the test, starting with growth curves to observe the behavior of the protozoan cultures. Multiple assays were then performed, modifying certain variables such as initial inoculum, culture phase, or reagent concentrations, resulting in an effective standardized protocol. The results of this study can be of great utility in identifying compounds with activity against G. duodenalis.Asociación Parasitológica Argentin

Quantum time machine

The continuation of Misner space into the Euclidean region is seen to imply the topological restriction that the period of the closed spatial direction becomes time-dependent. This restriction results in a modified Lorentzian Misner space in which the renormalized stress-energy tensor for quantized complex massless scalar fields becomes regular everywhere, even on the chronology horizon. A quantum-mechanically stable time machine with just the sub-microscopic size may then be constructed out of the modified Misner space, for which the semiclassical Hawking's chronology protection conjecture is no longer an obstruction.Comment: 6 pages, RevTe