3,798 research outputs found
Finance and growth in the EU: new evidence from the liberalisation and harmonisation of the banking industry
JEL Classification: G21, G28, O5Banking Deregulation, Economic Growth, European Union, Financial Development
Persistence in inequalities across the Spanish regions
In this paper we investigate several issues concerning persistence in inequalities of relative income per capita among the Spanish regions over 1980-2002. For that purpose we take a Bayesian approach which extends the work by Canova and Marcet (1995). Firstly, we study to what extent there exists a fixed effect bias in the standard cross-section estimates, and we find that the speed of convergence is indeed underestimated. Secondly, we provide a battery of results in which steady states and convergence rates have been obtained for a continuum of prior distributions. Finally, we also deal with persistence in inequalites by determining whether initial conditions matter in the distribution of regional steady states, and our conclusion is that regional disparities tend to persist over time in Spain.Convergence, Inequalities, Bayesian Econometrics, Gibbs sampling
Public finances and long-term growth in Europe - evidence from a panel data analysis
In Lisbon the European Council proclaimed a European growth strategy. It considers an average economic growth rate of around 3 percent as a realistic prospect for the coming years and assigns public finances an important role in the process of achieving this goal. This paper addresses the question whether we can find empirical evidence for European countries that public finance reform affects trend growth. Focusing on time series patterns, we investigate whether there have been persistent shifts or trends in economic growth and fiscal variables over the last 40 years. In addition, we estimate a distributed lag model, which 1) indicates that government consumption and transfers negatively affect growth rates of GDP per capita over the business cycle, while public investment has a positive impact, and 2) provides robust evidence that distortionary taxation affects growth in the medium-term through its impact on the accumulation of private physical capital. JEL Classification: C22, C23, H11, O11Europe, long-term growth, public finance
Persistence in inequalities across the Spanish regions.
This paper investigates several issues concerning persistence in inequalities of relative income per capita among the Spanish regions over 1980-2002. For that purpose we take a Bayesian approach which extends the work by Canova and Marcet (1995). Firstly, we study to what extent there exists a fixed effect bias in the standard cross-section estimates, and we find that the speed of convergence is indeed underestimated. Secondly, we provide a battery of results in which steady states and convergence rates have been obtained for a continuum of prior distributions. Finally, we also deal with persistence in inequalites by determining whether initial conditions matter in the distribution of regional steady states, and our conclusion is that regional disparities tend to persist over time in Spain.Convergence, Inequalities, Bayesian Econometrics, Gibbs sampling.
Plant surfaces as vehicles of Bacillus cereus responsible of human food poisoning
• Introduction
A major concern in food safety is the contamination of fresh and stored food with spoiling bacteria that provoke human poisoning. Bacillus cereus is a common food-borne pathogen responsible of important poisoning outbreaks and severe bacteraemia and septicaemia. Poisoning caused by B. cereus is classified in two main categories: emetic and diarrheic. The emetic poisoning is correlated to the production of cereulide. This toxin is very heat stable, and it can be produced in the food contaminated by B. cereus cells. Diarrheic poisoning is provoked by the enterotoxin hemolysin BL, the non-hemolytic enterotoxin and the cytotoxin K.
• Objective
To study the interaction of B. cereus with plants as a bacteria reservoir, and in ready-to-eat fruits and vegetables.
• Materials & Methods
A collection of strains implicated in food-borne outbreaks were tested in vitro for a battery of phenotypes related to bacterial multicellular behaviour and thus interaction with host.
1. Solid or liquid media were used to study biofilm formation, motility or adhesion to surfaces.
2. Leaves, fruits and vegetables (melon leaf, cucumber leaf and fruit and endive) were used to study the persistence of B. cereus over time and their distribution and organization by electron microscopy.
• Results
All the strains behaved similarly in vitro, only some persisted on plant surfaces. Among them, the emetic strain AH187 was selected because bacterial cells persisted on a concentration of 104-105 CFU per gram of leaf, vegetable or fruit, with a sporulation rate of 40%. The electron microscopy images showed the organization of bacteria in well-developed biofilms with visible extracellular matrix. Finally, mass spectrometry analysis proved the presence of some isoforms of cereluide on the different surfaces.
• Conclusion
The fact that cells of B. cereus persist in leaf surface mainly as vegetative cells are indicative of their ability to adapt to the physico-chemical changeable phyllosphere, and thus to produce the emetic toxin cereulide. The presence of spores, and the formation of biofilms can be indicative of the versatile adhesive properties of this strain to diverse surfaces. Altogether are supportive of the importance of plant surfaces either as reservoir of bacterial cells or as vehicles for further contamination and food poisoning.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
An improved method for the identification of galaxy systems: Measuring the gravitational redshift by Dark Matter Haloes
We introduce a new method for the identification of galaxy systems in
redshift surveys based on the halo model. This method is a modified version of
the K-means identification algorithm developed by Yang et al (2005). We have
calibrated and tested our algorithms using mock catalogs generated using the
Millennium simulations (Springel et al. 2005) and applied them to the NYU-DR7
galaxy catalog (based on the SDSS datasets). Using this local sample of groups
and clusters of galaxies we have measured the effect of gravitational redshift
produced by their host dark matter haloes. Our results shows radial velocity
decrements consistent with general relativity predictions and previous
measurements by Wojtak et al (2011) in clusters of galaxies.Comment: Accepted for Publication in MNRAS Letters, 2 figures. arXiv admin
note: text overlap with arXiv:astro-ph/0405234, arXiv:astro-ph/0406593 by
other author
Extracellular matrix components are required to protect bacillus subtilis from pseudomonas invasion and co-colonization of plants
Plants are colonized by a vast variety of microbes. Among them, bacteria are the most predominant and are able to adapt to environmental changes and interact with other microorganisms using a wide array of molecules, metabolic plasticity and secretion systems. One way bacteria have evolved to succeed in this competitive scenario is the formation of biofilms which provides protection to the cells, modulates the flux of signals and controls cellular differentiation. Thus, efforts are encouraged to really determine the functionality of the bacterial extracellular matrix.
In this study, we have employed microbiological and microscopic techniques to study the interaction between Bacillus subtilis 3610 and Pseudomonas chlororaphis PCL1606. We demonstrate the important role of the extracellular matrix in protecting B. subtilis colonies from infiltration by Pseudomonas. Furthermore, time-lapse confocal laser scanning microscopy (CLSM) analyses of the bacterial interactions have permitted to complete the study of the bacterial behaviors and to measure bacterial expansion rates. Surprising, we find that the Pseudomonas type VI secretion system (T6SS) is required in the cell-to-cell contact with matrix-impaired B. subtilis cells, revealing a novel role for T6SS against Gram-positive bacteria. In response to P. chlororaphis infiltration, we find that B. subtilis activates sporulation and expresses motility-related genes. Confocal microscopy of the bacterial interactions using plant organs highlights the functional importance of these different bacterial strategies in their coexistence as stable bacterial communities. The findings further our understanding of the functional role played by biofilms in mediating bacterial social interactions.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Analysis of the molecular machinery implicated in multicellularity in bacillus cereus
Introduction:
Bacillus cereus is a Gram-positive bacterium usually implicated in food poisoning outbreaks and human infections that sometimes result fatal. These events are closely related to the assembly of a biofilm that serves as a reservoir of cells, a nest for sporulation and protection from environmental stresses, host defenses or chemotherapy.
Objectives:
To perform a comprehensive comparative study of biofilm and planktonic cells to: i) delineate the molecular machinery implicated in the different steps of the biofilm life cycle, and ii) define new genes dedicated to biofilm formation.
Materials & methods:
Bacteria were grown under biofilm inducing conditions. Biofilm cells were separated from planktonic cells at different times and their whole mRNA was isolated, sequenced and analyzed.
Results:
Our results reveal a high number of genes associated to biofilm, many of them with unknown function, but highly conserved in others bacterial species. Besides, we found global changes in cell wall synthesis, metabolism and interspecies interaction molecules.
Conclusions:
The interaction of B. cereus with other bacteria is conditioned by secondary metabolites, which are apparently overexpressed in biofilm. On the other hand, toxins are mainly expressed in planktonic cells, which are more oriented to interact with its hosts. These results reveal the defense and attacking positions of B. cereus in biofilm vs planktonic states.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
A short version of the amyloid-like protein TasA fibrillates and supports biofilm formation in Bacillus cereus
The formation of bacterial biofilms is a doable thanks to the assembly of an extracellular matrix that provides to the entire
community with i) an outstanding architectonic structure and ii) protection to the cells from external aggressions. In
Bacillus subtilis, a structural element dedicated to the formation of the extracellular matrix is the amyloid-like protein TasA.
To form fibers, TasA needs the participation of the protein TapA. Indeed, a tapA mutant resembles phenotypically to a
tasA mutant, which is wrinkle-less pellicles or colonies with no distinguishable morphological features. tasA is widely
spread within the Bacillus genus, but tapA is absent in the heterogeneous group of Bacillus cereus which includes
environmental and pathogenic members; some of them are responsible for important food intoxication outbreaks. Then,
we asked whether TasA would still retain functionality in biofilm formation in B. cereus. Comparative genomic analysis
showed a region in B. cereus containing two orthologous of tasA, tasA and calY, and the orthologous of sipW, that
encodes a signal peptidase. Our mutagenic studies revealed that the entire region was relevant for biofilm formation, and
electron microscopy proved the major propensity of TasA than CalY to form fibers in the cell surfaces. These findings also
indicated that in B. cereus as opposed to B. subtilis, an accessory TapA protein is not necessary for the fibrillation of
TasA. Indeed, the heterologous expression of this region of B. cereus restored the capacity of a B. subtilis tasA operon
mutant or a single tasA mutant to form pellicles. These pellicles stained with the amyloid dye Congo Red and the cells
were decorated with fibers, both findings suggestive of an amyloid-like nature of the B. cereus TasA. Intriguingly, in a B.
subtilis tapA mutant, only the entire region of B. cereus fully rescued pellicle formation, fibrillation or Congo Red staining,
to a lesser extent did sipw-tasA, and no restoration was observed with sipW-calY. These observations led us to speculate
that TapA might cross seed the fibrillation of TasA or CalY in B. subtilis. In summary, TasA is relevant for biofilm formation
in these two bacterial species, which appears to be governed by its polymerizing nature. The fact that we count with two
bacterial species containing versions of TasA with subtle differences will be of great value in our studies of the
mechanistic of polymerization of these bacterial amyloid-like fibers and their contribution to the assembly of the
extracellular matrix.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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