235 research outputs found
The Role of Slotting Fees in the Coordination of Assortment Decisions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72029/1/j.1937-5956.2009.01039.x.pd
Toward a Novel Multilocus Phylogenetic Taxonomy for the Dermatophytes.
Type and reference strains of members of the onygenalean family Arthrodermataceae have been sequenced for rDNA ITS and partial LSU, the ribosomal 60S protein, and fragments of β-tubulin and translation elongation factor 3. The resulting phylogenetic trees showed a large degree of correspondence, and topologies matched those of earlier published phylogenies demonstrating that the phylogenetic representation of dermatophytes and dermatophyte-like fungi has reached an acceptable level of stability. All trees showed Trichophyton to be polyphyletic. In the present paper, Trichophyton is restricted to mainly the derived clade, resulting in classification of nearly all anthropophilic dermatophytes in Trichophyton and Epidermophyton, along with some zoophilic species that regularly infect humans. Microsporum is restricted to some species around M. canis, while the geophilic species and zoophilic species that are more remote from the human sphere are divided over Arthroderma, Lophophyton and Nannizzia. A new genus Guarromyces is proposed for Keratinomyces ceretanicus. Thirteen new combinations are proposed; in an overview of all described species it is noted that the largest number of novelties was introduced during the decades 1920-1940, when morphological characters were used in addition to clinical features. Species are neo- or epi-typified where necessary, which was the case in Arthroderma curreyi, Epidermophyton floccosum, Lophophyton gallinae, Trichophyton equinum, T. mentagrophytes, T. quinckeanum, T. schoenleinii, T. soudanense, and T. verrucosum. In the newly proposed taxonomy, Trichophyton contains 16 species, Epidermophyton one species, Nannizzia 9 species, Microsporum 3 species, Lophophyton 1 species, Arthroderma 21 species and Ctenomyces 1 species, but more detailed studies remain needed to establish species borderlines. Each species now has a single valid name. Two new genera are introduced: Guarromyces and Paraphyton. The number of genera has increased, but species that are relevant to routine diagnostics now belong to smaller groups, which enhances their identification
Nuevo prototipo de máquina frigorífica de absorción de LiBr-H₂O de simple y doble efecto con absorbedor adiabático refrigerado por aire de alta eficiencia : descripción, simulación y resultados experimentales
Due to unsustainable growth of air conditioning market, a great interest in solar cooling technologies has emerged. The coincidence between availability of solar irradiation and peaks of cooling demand makes solar cooling a very attractive option to replace conventional refrigeration machines based on electricity. What is more, solar cooling systems normally use natural refrigerants that are not harmful to the environment. However, an improvement of the current technology is needed for solar cooling systems to compete with electricity‐powered air conditioning systems. In this work, a novel air‐cooled single–double‐effect LiBr/H₂O absorption prototype is proposed as a solution to improve the viability of solar cooling systems. This prototype presents the following distinguishing features: firstly, it is directly air‐cooled, which means that no cooling tower is needed; secondly, it is made up by compact heat exchangers, which allows for a reduced size of about 1 m₃; thirdly, it incorporates an adiabatic absorber operating with flat‐fan solution sheets, which permits the working solution not to crystallize at high ambient temperatures; lastly, it can be powered by solar heat in its single‐effect mode (4.5 kW), or by an alternative source such as fuel or waste heat in its double‐effect stage (7 kW). In this way, 100% of the cooling demand may be supplied by a single absorption machine using solar energy as far as possible or, when it is not available, efficiently utilizing a fuel or even waste heat, for instance in a trigeneration system. This thesis includes a detailed description of that single–double‐effect absorption prototype as well as the fundamentals for its numerical simulation. Likewise, experimental results from a testing campaign carried out in Madrid during 2010 are presented and discussed. A solar facility with evacuated flat‐plate collectors was used to test the single-effect operation mode of the prototype. In turn, the double‐effect stage was fired by a thermal oil facility with electrical resistances. As relevant results of the whole experimental campaign it is worth mentioning that the single‐effect stage was able to work with COP values around 0.6, whereas the double‐effect mode permitted to achieve values of about 1.0. The chilled water temperatures mostly ranged between 14°C and 16°C in single‐effect operation mode, while they were around 12°C for the double‐effect stage. Besides, it is highly noteworthy that after some 125 hours of operation under a wide range of conditions (outdoor temperatures up to 39.5°C), no solution crystallization was noticed. On the other hand, this work includes an in‐depth description of the absorber assembled in the single–double‐effect prototype. Furthermore, a mathematical model is developed for simulation of air‐cooled flat‐fan sheets adiabatic absorbers. As far as we know, there is not any numerical modeling for this kind of absorbers in the literature. Based on that model, which was as well experimentally validated in this study, the capacity of the prototype absorber is optimized as a function of the energy consumption of its ancillary equipment (solution pump and fan). Finally, the positive results derived from this work may be regarded as an important contribution to the development of air‐cooled LiBr/H₂O absorption technology. Even though a few improvements in the prototype are still required, it seems that the proposed system represents a feasible alternative to overcome some of the major obstacles concerning solar air conditioning. -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------La actual situación de insostenibilidad en el mercado de la climatización ha motivado un gran interés por la refrigeración solar como alternativa al uso de máquinas eléctricas. El hecho de que las horas de máxima radiación solar coincidan con los momentos de mayor demanda de frío en los edificios, hace que estos sistemas sean especialmente indicados para sustituir a los equipos convencionales de aire acondicionado. Además, hay que añadir que esta tecnología normalmente utiliza refrigerantes naturales que no son dañinos para el medio ambiente. Sin embargo, los sistemas actuales de refrigeración solar necesitan una mejora sustancial para poder competir directamente con los aparatos tradicionales de climatización. Como una posible solución para mejorar la viabilidad de los sistemas de refrigeración solar, en este trabajo se presenta un nuevo prototipo de máquina de absorción de LiBr/H₂O que integra los ciclos de simple y doble efecto en una misma unidad. Las principales características que hacen de este prototipo una novedad tecnológica son las siguientes: en primer lugar, se trata de una máquina directamente condensada por aire, eliminando así la necesidad de instalar torres de refrigeración; en segundo lugar, el prototipo está básicamente formado por intercambiadores de calor compactos, con lo que se alcanza un tamaño final de máquina muy reducido, aproximadamente 1 m3; en tercer lugar, el prototipo incorpora un absorbedor adiabático con láminas planas que evita que la disolución cristalice a altas temperaturas ; por último, la máquina puede funcionar como una unidad de simple efecto (4.5 kW), alimentada en este caso por energía solar, o como una unidad de doble efecto (7 kW), quemando combustibles o utilizando calor residual. De este modo, se podría llegar cubrir el 100% de la demanda de refrigeración con una sola unidad que saca el máximo partido a la energía solar y, cuando ésta no es suficiente, utiliza eficientemente combustibles o incluso el calor residual procedente de otros procesos, por ejemplo en una planta de trigeneración. En esta tesis doctoral se incluye una descripción detallada del prototipo de simple y doble efecto así como los fundamentos teóricos para su simulación numérica. Asimismo, se presentan y discuten los resultados experimentales obtenidos durante una campaña de ensayos llevada a cabo en Madrid durante el año 2010. Para probar el funcionamiento del prototipo como máquina de absorción de simple efecto se ha utilizado una instalación solar con colectores planos de vacío. En cambio, para ensayar el prototipo como máquina de doble efecto se ha utilizado un aceite térmico como fuente de energía. Como resultados destacados de la campaña de experimentación cabe mencionar que los valores del COP se movieron entorno a 0.6 en simple efecto y alrededor de 1.0 en doble efecto. A su vez, se alcanzaron temperaturas de agua fría entre 14°C y 16°C para el simple efecto y de aproximadamente 12°C para el doble efecto. Además, es de gran relevancia el hecho de que, después de unas 125 horas de funcionamiento bajo condiciones de trabajo muy diferentes (hasta 39.5°C de temperatura exterior), la disolución de LiBr/H₂O no se haya cristalizado en ningún momento. Por otra parte, este trabajo incluye una descripción detallada del absorbedor instalado en el prototipo. Asimismo, se ha desarrollado un modelo matemático para simular absorbedores adiabáticos de láminas directamente refrigerados por aire. Por lo que sabemos, hasta el momento no se ha publicado ninguna modelización numérica para este tipo de absorbedores. Tomando como referencia el modelo propuesto, que también ha sido validado experimentalmente en este estudio, se ha realizado una optimización de la capacidad del absorbedor del prototipo en función del consumo energético de sus equipos auxiliares (bomba de disolución y ventilador). Por último, los buenos resultados obtenidos con este prototipo nos hacen pensar que este trabajo representa una contribución importante al desarrollo de las máquinas de absorción de LiBr/H₂O refrigeradas por aire. A pesar de que el prototipo todavía no está totalmente optimizado, con él se ha demostrado que la tecnología propuesta en esta tesis doctoral constituye una alternativa viable para superar algunos de los principales problemas relacionados con la refrigeración solar
Pathotypic diversity of Hyaloperonospora brassicae collected from Brassica oleracea
Downy mildew caused by Hyaloperonospora brassicae is an economically destructive disease of brassica crops in many growing regions throughout the world. Specialised pathogenicity of downy mildews from different Brassica species and closely related ornamental or wild relatives has been described from host range studies. Pathotypic variation amongst Hyaloperonospora brassicae isolates from Brassica oleracea has also been described; however, a standard set of B. oleracea lines that could enable reproducible classification of H. brassicae pathotypes was poorly developed. For this purpose, we examined the use of eight genetically refined host lines derived from our previous collaborative work on downy mildew resistance as a differential set to characterise pathotypes in the European population of H. brassicae. Interaction phenotypes for each combination of isolate and host line were assessed following drop inoculation of cotyledons and a spectrum of seven phenotypes was observed based on the level of sporulation on cotyledons and visible host responses. Two host lines were resistant or moderately resistant to the entire collection of isolates, and another was universally susceptible. Five lines showed differential responses to the H. brassicae isolates. A minimum of six pathotypes and five major effect resistance genes are proposed to explain all of the observed interaction phenotypes. The B. oleracea lines from this study can be useful for monitoring pathotype frequencies in H. brassicae populations in the same or other vegetable growing regions, and to assess the potential durability of disease control from different combinations of the predicted downy mildew resistance genes
Natural history of Arabidopsis thaliana and oomycete symbioses
Molecular ecology of plant–microbe interactions has immediate significance for filling a gap in knowledge between the laboratory discipline of molecular biology and the largely theoretical discipline of evolutionary ecology. Somewhere in between lies conservation biology, aimed at protection of habitats and the diversity of species housed within them. A seemingly insignificant wildflower called Arabidopsis thaliana has an important contribution to make in this endeavour. It has already transformed botanical research with deepening understanding of molecular processes within the species and across the Plant Kingdom; and has begun to revolutionize plant breeding by providing an invaluable catalogue of gene sequences that can be used to design the most precise molecular markers attainable for marker-assisted selection of valued traits. This review describes how A. thaliana and two of its natural biotrophic parasites could be seminal as a model for exploring the biogeography and molecular ecology of plant–microbe interactions, and specifically, for testing hypotheses proposed from the geographic mosaic theory of co-evolution
Demonstration of the histopathological and immunohistochemical effects of a novel hemostatic agent, ankaferd blood stopper, on vascular tissue in a rat aortic bleeding model
Background: Ankaferd Blood Stopper®(ABS) is a folkloric medicinal plant extract used as a hemostatic agent in traditional Turkish medicine. This experimental study investigated the histopathological and immunohistochemical effects of ABS on vascular tissue in a rat model of aortic bleeding.Methods: Four groups of 11 Wistar albino rats were used. The abdominal aortas of the rats were wounded; an ABS-soaked tampon was applied to rats in Groups 1 and 3, and a plain gauze tampon was applied to rats in Groups 2 and 4 until the bleeding stopped. The bleeding time was recorded. Immediately following sacrificing, the arteriotomy sites from Groups 1 and 2 were removed. The abdominal incisions in Groups 3 and 4 were closed following hemostasis. On Day 7 of the study, Group 3 and 4 rats were sacrificed and the abdominal aorta arteriotomy sites were removed for histopathological and immunohistochemical evaluation.Results: The mean bleeding time in 15 animals in Groups 2 and 4 was 4.9 ± 0.6 s, and in 22 animals in Groups 1 and 3 was 3.1 ± 0.6 s. Distal aortic occlusion was not observed on either Day 1 or 7 in any group. Significantly more widespread and dense endothelial nitric oxide synthase (eNOS) staining was observed in Group 1 animals than Group 2. On Days 1 and 7 after application of ABS, histopathological changes, consisting of necrosis, inflammation, and endothelial cell loss, in the rat abdominal aortas did not differ between Groups 1 and 2. The basophilic discoloration in the ABS group on the operation day was a result of a foreign body reaction and hemosiderin-loaded histiocyte accumulation, which occurred on Day 7.Conclusions: In this study, hemostasis was successfully achieved with ABS in rat abdominal aortas. No histopathological change was found in the rat abdominal aortas between the ABS and control groups on Days 1 and 7. Further studies on the long-term effects of foreign body reactions and hemosiderin-loaded histiocyte accumulation are required. © 2010 Kandemir et al; licensee BioMed Central Ltd
Ongoing diversification of the global fish pathogen Piscirickettsia salmonis through genetic isolation and transposition bursts
The management of bacterial pathogens remains a key challenge of aquaculture. The marine gammaproteobacterium Piscirickettsia salmonis is the etiological agent of piscirickettsiosis and causes multi-systemic infections in different salmon species, resulting in considerable mortality and substantial commercial losses. Here, we elucidate its global diversity, evolution, and selection during human interventions. Our comprehensive analysis of 73 closed, high quality genome sequences covered strains from major outbreaks and was supplemented by an analysis of all P. salmonis 16S rRNA gene sequences and metagenomic reads available in public databases. Genome comparison showed that Piscirickettsia comprises at least three distinct, genetically isolated species of which two showed evidence for continuing speciation. However, at least twice the number of species exist in marine fish or seawater. A hallmark of Piscirickettsia diversification is the unprecedented amount and diversity of transposases which are particularly active in subgroups undergoing rapid speciation and are key to the acquisition of novel genes and to pseudogenization. Several group-specific genes are involved in surface antigen synthesis and may explain the differences in virulence between strains. However, the frequent failure of antibiotic treatment of piscirickettsiosis outbreaks cannot be explained by horizontal acquisition of resistance genes which so far occurred only very rarely. Besides revealing a dynamic diversification of an important pathogen, our study also provides the data for improving its surveillance, predicting the emergence of novel lineages, and adapting aquaculture management, and thereby contributes towards the sustainability of salmon farming
Species Delimitation in Taxonomically Difficult Fungi: The Case of Hymenogaster
False truffles are ecologically important as mycorrhizal partners of trees and evolutionarily highly interesting as the result of a shift from epigeous mushroom-like to underground fruiting bodies. Since its first description by Vittadini in 1831, inappropriate species concepts in the highly diverse false truffle genus Hymenogaster has led to continued confusion, caused by a large variety of prevailing taxonomical opinions.In this study, we reconsidered the species delimitations in Hymenogaster based on a comprehensive collection of Central European taxa comprising more than 140 fruiting bodies from 20 years of field work. The ITS rDNA sequence dataset was subjected to phylogenetic analysis as well as clustering optimization using OPTSIL software.Among distinct species concepts from the literature used to create reference partitions for clustering optimization, the broadest concept resulted in the highest agreement with the ITS data. Our results indicate a highly variable morphology of H. citrinus and H. griseus, most likely linked to environmental influences on the phenology (maturity, habitat, soil type and growing season). In particular, taxa described in the 19(th) century frequently appear as conspecific. Conversely, H. niveus appears as species complex comprising seven cryptic species with almost identical macro- and micromorphology. H. intermedius and H. huthii are described as novel species, each of which with a distinct morphology intermediate between two species complexes. A revised taxonomy for one of the most taxonomically difficult genera of Basidiomycetes is proposed, including an updated identification key. The (semi-)automated selection among species concepts used here is of importance for the revision of taxonomically problematic organism groups in general
Improving phylogeny reconstruction at the strain level using peptidome datasets
Typical bacterial strain differentiation methods are often challenged by high genetic similarity between strains. To address this problem, we introduce a novel in silico peptide fingerprinting method based on conventional wet-lab protocols that enables the identification of potential strain-specific peptides. These can be further investigated using in vitro approaches, laying a foundation for the development of biomarker detection and application-specific methods. This novel method aims at reducing large amounts of comparative peptide data to binary matrices while maintaining a high phylogenetic resolution. The underlying case study concerns the Bacillus cereus group, namely the differentiation of Bacillus thuringiensis, Bacillus anthracis and Bacillus cereus strains. Results show that trees based on cytoplasmic and extracellular peptidomes are only marginally in conflict with those based on whole proteomes, as inferred by the established Genome-BLAST Distance Phylogeny (GBDP) method. Hence, these results indicate that the two approaches can most likely be used complementarily even in other organismal groups. The obtained results confirm previous reports about the misclassification of many strains within the B. cereus group. Moreover, our method was able to separate the B. anthracis strains with high resolution, similarly to the GBDP results as benchmarked via Bayesian inference and both Maximum Likelihood and Maximum Parsimony. In addition to the presented phylogenomic applications, whole-peptide fingerprinting might also become a valuable complementary technique to digital DNA-DNA hybridization, notably for bacterial classification at the species and subspecies level in the future.This research was funded by Grant AGL2013-44039-R from the Spanish “Plan Estatal de I+D+I”, and by Grant EM2014/046 from the “Plan Galego de investigación, innovación e crecemento 2011-2015”. BS was recipient of a Ramón y Cajal postdoctoral contractfrom the Spanish Ministry of Economyand Competitiveness. This work was also partially funded by the [14VI05] Contract-Programme from the University of Vigo and the Agrupamento INBIOMED from DXPCTSUG-FEDER unha maneira de facer Europa (2012/273).The research leading to these results has also received funding from the European Union’s Seventh Framework Programme FP7/REGPOT-2012-2013.1 under grant agreement n˚ 316265, BIOCAPS. This document reflects only the authors’ views and the European Union is not liable for any use that may be made of the information contained herein. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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