330 research outputs found
The failed liberalisation of Algeria and the international context: a legacy of stable authoritarianism
The paper attempts to challenge the somewhat marginal role of international factors in the study of transitions to democracy. Theoretical and practical difficulties in proving causal mechanisms between international variables and domestic outcomes can be overcome by defining the international dimension in terms of Western dominance of world politics and by identifying Western actions towards democratising countries. The paper focuses on the case of Algeria, where international factors are key in explaining the initial process of democratisation and its following demise. In particular, the paper argues that direct Western policies, the pressures of the international system and external shocks influence the internal distribution of power and resources, which underpins the different strategies of all domestic actors. The paper concludes that analysis based purely on domestic factors cannot explain the process of democratisation and that international variables must be taken into more serious account and much more detailed
Urban ornithology in the Neotropics: status and challenge
La región Neotropical presenta una gran diversidad de aves y un alto nivel de urbanización, sin embargo, es una de las regiones menos estudiadas en relación a la ornitología urbana. Muchas aves de esta región están sufriendo decrecimientos poblacionales importantes debido a impactos antrópicos por lo cual es fundamental analizar los efectos de la urbanización sobre las aves en el Neotrópico. En base a una revisión bibliográfica encontramos 270 estudios sobre ornitología urbana en el Neotrópico, casi la mitad de las investigaciones se enfocan en ecología espacial, y sólo tres países (Brasil, México y Argentina) concentran más del 60% de las investigaciones. Este Número Especial incluye 20 artículos sobre ornitología urbana con la participación de investigadores de seis países de la región. En estos trabajos -que incluyen puntos de vista, revisiones bibliográficas, metodologías y ayudas en investigación, artículos y comunicaciones cortas-, se analizan diferentes temáticas como el cambio de la diversidad de aves y poblaciones a través de gradientes urbanos y del tiempo, depredación de nidos y mortandad de adultos en ambientes urbanos. En comparación a las temáticas abordadas anteriormente en la región, este Número Especial se destaca por sus trabajos sobre demografía y comportamiento de aves. Resaltamos la necesidad de realizar más investigaciones sobre cambios demográficos de las especies, análisis de factores abióticos como la luz artificial o el ruido, y estudios a múltiples escalas espaciales y temporales.The Neotropical region has one of the greatest bird diversity in the world and, in turn, faces future increases in the human population that inhabits cities. Many birds in this region are experiencing significant population declines due to anthropogenic impacts, which is why it is essential to analyze the effects of urbanization on birds in the Neotropics. Based on a bibliographic review, we found 270 studies on urban ornithology in the Neotropics, almost half of the investigations focus on spatial ecology, and only three countries (Brazil, Mexico and Argentina) concentrate more than 60% of the investigations. This Special Issue includes 20 articles on urban ornithology with the participation of researchers from six countries from the region. In these works-which include points of view, bibliographical reviews, methodologies and research support, articles and short communications-, different topics are analyzed such as the change in bird diversity and population numbers along urban and temporal gradients, nest predation and adult mortality in urban environments. Compared to the topics previously addressed in the region, this Special Issue stands out for its works on demography and bird behavior. According to published articles, more studies are needed on species demography, and impacts of abiotic factors such as artificial light and noise, and multiple spatial scales analyses.Fil: Leveau, Lucas Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Villaseñor, Nélida R.. Universidad de Chile; Chile. Universidad Bernardo O'higgins; ChileFil: Lambertucci, Sergio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin
Understanding the physiology of Lactobacillus plantarum at zero growth
The physiology of Lactobacillus plantarum at extremely low growth rates, through cultivation in retentostats, is much closer to carbon-limited growth than to stationary phase, as evidenced from transcriptomics data, metabolic fluxes, and biomass composition and viability.Using a genome-scale metabolic model and constraint-based computational analyses, amino-acid fluxes—in particular, the rather paradoxical excretion of Asp, Arg, Met, and Ala—could be rationalized as a means to allow extensive metabolism of other amino acids, that is, that of branched-chain and aromatic amino acids.Catabolic products from aromatic amino acids are known to have putative plant-hormone action. The metabolism of amino acids, as well as transcription data, strongly suggested a plant environment-like response in slow-growing L. plantarum, which was confirmed by significant effects of fermented medium on plant root formation
Parámetros hematológicos y laboratoriales tempranos asociados con la mortalidad por COVID-19 en una población amazónica del Perú
COVID-19 has a significant impact on the hematopoietic system and hemostasis. Leukocytosis, lymphopenia, and thrombocytopenia are associated with increased severity and even death in COVID-19 cases. Objective: The aim is to examine the laboratory results of COVID-19 patients from a hospital in the Peruvian Amazon and their clinical prognosis. Material and Methods: An analytical cross-sectional study was carried out whose purpose was to identify the laboratory tests of patients with COVID-19 and mortality in a hospital in Ucayali, Peru during the period from March 13 to May 9, 2020, selecting a total of 127 with Covid-19. Mean and the standard deviation was described for age, leukocytes, neutrophils, platelets, RDW-SD; median and interquartile range for the variables lymphocyte, RN / L, fibrinogen, CRP, D-dimer, DHL, hematocrit, monocytes, eosinophils. Results: No differences were observed in this population regarding death and sex (OR: 1.31; 95% CI 0.92 to 1.87), however, it was observed that, for each one-year increase, the probability of death increased by 4% (PR: 1.04, 95% CI 1.03 to 1.05). The IRR (Incidence Risk Ratio) analysis for the numerical variables showed results strongly associated with hematological values such as Leukocytes (scaled by 2500 units) (IRR: 1.08, 95% CI 1.03 to 1.13), neutrophils (scaled by 2500 units) (IRR: 1.08; 95% CI 1.03 to 1.13), on the contrary, it is observed that the increase of 1000 units in lymphocytes, the probability of dying decreased by 48% (IRR: 0.52; 95% CI 0.38 to 071). Conclusions: Parameters such as leukocytes,neutrophils and D-dimer were statistically much higher in patients who died.COVID-19 tiene un impacto significativo en el sistema hematopoyético y la hemostasia. La leucocitosis, la linfopenia y la trombocitopenia se asocian con una mayor gravedad e incluso la muerte en los casos de COVID-19. Objetivo: examinar los resultados de laboratorio de pacientes con COVID-19 de un hospital de la Amazonía peruana y su pronóstico clínico. Material y métodos: Se realizó un estudio transversal analítico cuyo propósito fue identificar las pruebas de laboratorio de pacientes con COVID-19 y mortalidad en un hospital de Ucayali, Perú durante el periodo del 13 de marzo al 9 de mayo del 2020, seleccionando un total de 127 con COVID-19. Se describió la media y la desviación estándar para edad, leucocitos, neutrófilos, plaquetas, RDW-SD; mediana y rango intercuartílico para las variables linfocito, RN/L, fibrinógeno, PCR, dímero D, DHL, hematocrito, monocitos, eosinófilos. Resultados: No se observaron diferencias en esta población en cuanto a muerte y sexo (OR: 1,31; IC 95% 0,92 a 1,87), sin embargo, se observó que, por cada aumento de un año, la probabilidad de muerte aumentaba un 4% (RP: 1,04). , IC del 95%: 1,03 a 1,05). El análisis de RIR (Razón de incidencia de riesgos) para las variables numéricas mostró resultados fuertemente asociados con valores hematológicos como Leucocitos (escala de 2500 unidades) (RRI: 1.08, 95% CI 1.03 a 1.13), neutrófilos (escala de 2500 unidades) (RRI: 1.08; IC 95% 1.03 a 1.13), por el contrario, se observa que al aumento de 1000 unidades en linfocitos, la probabilidad de morir disminuyó en un 48% (TIR: 0.52; IC 95% 0.38 a 071). Conclusiones: Parámetros tales como los leucocitos, los neutrófilos y el dímero D fueron estadísticamente mucho más altos en los pacientes que fallecieron
Using synthetic biological parts and microbioreactors to explore the protein expression characteristics of Escherichia coli
Synthetic
biology has developed numerous parts for the precise
control of protein expression. However, relatively little is known
about the burden these place on a host, or their reliability under
varying environmental conditions. To address this, we made use of
synthetic transcriptional and translational elements to create a combinatorial
library of constructs that modulated expression strength of a green
fluorescent protein. Combining this library with a microbioreactor
platform, we were able to perform a detailed large-scale assessment
of transient expression and growth characteristics of two <i>Escherichia coli</i> strains across several temperatures. This
revealed significant differences in the robustness of both strains
to differing types of protein expression, and a complex response of
transcriptional and translational elements to differing temperatures.
This study supports the development of reliable synthetic biological
systems capable of working across different hosts and environmental
contexts. Plasmids developed during this work have been made publicly
available to act as a reference set for future research
Microbiology of the phyllosphere: a playground for testing ecological concepts
Many concepts and theories in ecology are highly debated, because it is often difficult to design decisive tests with sufficient replicates. Examples include biodiversity theories, succession concepts, invasion theories, coexistence theories, and concepts of life history strategies. Microbiological tests of ecological concepts are rapidly accumulating, but have yet to tap into their full potential to complement traditional macroecological theories. Taking the example of microbial communities on leaf surfaces (i.e. the phyllosphere), we show that most explorations of ecological concepts in this field of microbiology focus on autecology and population ecology, while community ecology remains understudied. Notable exceptions are first tests of the island biogeography theory and of biodiversity theories. Here, the phyllosphere provides the unique opportunity to set up replicated experiments, potentially moving fields such as biogeography, macroecology, and landscape ecology beyond theoretical and observational evidence. Future approaches should take advantage of the great range of spatial scales offered by the leaf surface by iteratively linking laboratory experiments with spatial simulation models
Technical Note: New ground-based FTIR measurements at Ile de La Réunion: observations, error analysis, and comparisons with independent data
Ground-based high spectral resolution Fourier-transform infrared (FTIR) solar absorption spectroscopy is a powerful remote sensing technique to obtain information on the total column abundances and on the vertical distribution of various constituents in the atmosphere. This work presents results from two FTIR measurement campaigns in 2002 and 2004, held at Ile de La Réunion (21° S, 55° E). These campaigns represent the first FTIR observations carried out at a southern (sub)tropical site. They serve the initiation of regular, long-term FTIR monitoring at this site in the near future. To demonstrate the capabilities of the FTIR measurements at this location for tropospheric and stratospheric monitoring, a detailed report is given on the retrieval strategy, information content and corresponding full error budget evaluation for ozone (O3), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), ethane (C2H6), hydrogen chloride (HCl), hydrogen fluoride (HF) and nitric acid (HNO3) total and partial column retrievals. Moreover, we have made a thorough comparison of the capabilities at sea level altitude (St.-Denis) and at 2200 m a.s.l. (Maïdo). It is proved that the performances of the technique are such that the atmospheric variability can be observed, at both locations and in distinct altitude layers. Comparisons with literature and with correlative data from ozone sonde and satellite (i.e., ACE-FTS, HALOE and MOPITT) measurements are given to confirm the results. Despite the short time series available at present, we have been able to detect the seasonal variation of CO in the biomass burning season, as well as the impact of particular biomass burning events in Africa and Madagascar on the atmospheric composition above Ile de La Réunion. We also show that differential measurements between St.-Denis and Maïdo provide useful information about the concentrations in the boundary layer.Peer reviewe
Salmonella Biofilm Formation on Aspergillus niger Involves Cellulose – Chitin Interactions
Salmonella cycles between host and nonhost environments, where it can become an active member of complex microbial communities. The role of fungi in the environmental adaptation of enteric pathogens remains relatively unexplored. We have discovered that S. enterica Typhimurium rapidly attaches to and forms biofilms on the hyphae of the common fungus, Aspergillus niger. Several Salmonella enterica serovars displayed a similar interaction, whereas other bacterial species were unable to bind to the fungus. Bacterial attachment to chitin, a major constituent of fungal cell walls, mirrored this specificity. Pre-incubation of S. Typhimurium with N-acetylglucosamine, the monomeric component of chitin, reduced binding to chitin beads by as much as 727-fold and inhibited attachment to A. niger hyphae considerably. A cellulose-deficient mutant of S. Typhimurium failed to attach to chitin beads and to the fungus. Complementation of this mutant with the cellulose operon restored binding to chitin beads to 79% of that of the parental strain and allowed for attachment and biofilm formation on A. niger, indicating that cellulose is involved in bacterial attachment to the fungus via the chitin component of its cell wall. In contrast to cellulose, S. Typhimurium curli fimbriae were not required for attachment and biofilm development on the hyphae but were critical for its stability. Our results suggest that cellulose–chitin interactions are required for the production of mixed Salmonella-A. niger biofilms, and support the hypothesis that encounters with chitinaceous alternate hosts may contribute to the ecological success of human pathogens
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