319 research outputs found
Liquid compressibility effects during the collapse of a single cavitating bubble
The effect of liquid compressibility on the dynamics of a single, spherical cavitating bubble is studied.
While it is known that compressibility damps the amplitude of bubble rebounds, the extent to which
this effect is accurately captured by weakly compressible versions of the Rayleigh–Plesset equation is
unclear. To clarify this issue, partial differential equations governing conservation of mass, momentum,
and energy are numerically solved both inside the bubble and in the surrounding compressible
liquid. Radiated pressure waves originating at the unsteady bubble interface are directly captured.
Results obtained with Rayleigh–Plesset type equations accounting for compressibility effects, proposed
by Keller and Miksis [J. Acoust. Soc. Am. 68, 628–633 (1980)], Gilmore, and Tomita and
Shima [Bull. JSME 20, 1453–1460 (1977)], are compared with those resulting from the full model.
For strong collapses, the solution of the latter reveals that an important part of the energy concentrated
during the collapse is used to generate an outgoing pressure wave. For the examples considered in
this research, peak pressures are larger than those predicted by Rayleigh–Plesset type equations,
whereas the amplitudes of the rebounds are smaller
Transcriptional responses are oriented towards different components of the rearing environment in two Drosophila sibling species
Background The chance to compare patterns of differential gene expression in related ecologically distinct species can be particularly fruitful to investigate the genetics of adaptation and phenotypic plasticity. In this regard, a powerful technique such as RNA-Seq applied to ecologically amenable taxa allows to address issues that are not possible in classic model species. Here, we study gene expression profiles and larval performance of the cactophilic siblings Drosophila buzzatii and D. koepferae reared in media that approximate natural conditions and evaluate both chemical and nutritional components of the diet. These closely related species are complementary in terms of host-plant use since the primary host of one is the secondary of the other. D. koepferae is mainly a columnar cactus dweller while D. buzzatii prefers Opuntia hosts. Results Our comparative study shows that D. buzzatii and D. koepferae have different transcriptional strategies to face the challenges posed by their natural resources. The former has greater transcriptional plasticity, and its response is mainly modulated by alkaloids of its secondary host, while the latter has a more canalized genetic response, and its transcriptional plasticity is associated with the cactus species. Conclusions Our study unveils a complex pleiotropic genetic landscape in both species, with functional links that relate detox responses and redox mechanisms with developmental and neurobiological processes. These results contribute to deepen our understanding of the role of host plant shifts and natural stress driving ecological specialization
Joint PDF modelling of turbulent flow and dispersion in an urban street canyon
The joint probability density function (PDF) of turbulent velocity and
concentration of a passive scalar in an urban street canyon is computed using a
newly developed particle-in-cell Monte Carlo method. Compared to moment
closures, the PDF methodology provides the full one-point one-time PDF of the
underlying fields containing all higher moments and correlations. The
small-scale mixing of the scalar released from a concentrated source at the
street level is modelled by the interaction by exchange with the conditional
mean (IECM) model, with a micro-mixing time scale designed for geometrically
complex settings. The boundary layer along no-slip walls (building sides and
tops) is fully resolved using an elliptic relaxation technique, which captures
the high anisotropy and inhomogeneity of the Reynolds stress tensor in these
regions. A less computationally intensive technique based on wall functions to
represent boundary layers and its effect on the solution are also explored. The
calculated statistics are compared to experimental data and large-eddy
simulation. The present work can be considered as the first example of
computation of the full joint PDF of velocity and a transported passive scalar
in an urban setting. The methodology proves successful in providing high level
statistical information on the turbulence and pollutant concentration fields in
complex urban scenarios.Comment: Accepted in Boundary-Layer Meteorology, Feb. 19, 200
Pancreatic cancer
The need for a common education and training track in surgical oncology across Europe has been emphasized. ESSO provides several hands-on courses for skills training and face-to-face discussions. The core curriculum provides a framework for the overall theoretical requirements in surgical oncology. The UEMS/EBSQ fellowship exam is designed to test core competencies in the candidate's core knowledge in their prespecified area of expertise. A core set of points for each cancer type is lacking. Hence, a condensed outline of themed expected to be covered in the curriculum and relevant to an optimal practice in surgical oncology is provided. This article outlines pancreatic cancer. (c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Surgical oncolog
Sexual selection drives weak positive selection in protamine genes and high promoter divergence, enhancing sperm competitiveness
Phenotypic adaptations may be the result of changes in gene structure or gene regulation, but little is known about the evolution of gene expression. In addition, it is unclear whether the same selective forces may operate at both levels simultaneously. Reproductive proteins evolve rapidly, but the underlying selective forces promoting such rapid changes are still a matter of debate. In particular, the role of sexual selection in driving positive selection among reproductive proteins remains controversial, whereas its potential influence on changes in promoter regions has not been explored. Protamines are responsible for maintaining DNA in a compacted form in chromosomes in sperm and the available evidence suggests that they evolve rapidly. Because protamines condense DNA within the sperm nucleus, they influence sperm head shape. Here, we examine the influence of sperm competition upon protamine 1 and protamine 2 genes and their promoters, by comparing closely related species of Mus that differ in relative testes size, a reliable indicator of levels of sperm competition. We find evidence of positive selection in the protamine 2 gene in the species with the highest inferred levels of sperm competition. In addition, sperm competition levels across all species are strongly associated with high divergence in protamine 2 promoters that, in turn, are associated with sperm swimming speed. We suggest that changes in protamine 2 promoters are likely to enhance sperm swimming speed by making sperm heads more hydrodynamic. Such phenotypic changes are adaptive because sperm swimming speed may be a major determinant of fertilization success under sperm competition. Thus, when species have diverged recently, few changes in gene-coding sequences are found, while high divergence in promoters seems to be associated with the intensity of sexual selection
The EGR2 gene is involved in axonal Charcot-Marie-Tooth disease
[EN]
Background and purpose: A three-generation family affected by axonal Charcot-Marie-Tooth disease (CMT) was investigated with the aim of discovering genetic defects and to further characterize the phenotype.
Methods: The clinical, nerve conduction studies and muscle magnetic resonance images of the patients were reviewed. A whole exome sequencing was performed and the changes were investigated by genetic studies, in silico analysis and luciferase reporter assays.
Results: A novel c.1226G>A change (p.R409Q) in the EGR2 gene was identified. Patients presented with a typical, late-onset axonal CMT phenotype with variable severity that was confirmed in the ancillary tests. The in silico studies showed that the residue R409 is an evolutionary conserved amino acid. The p.R409Q mutation, which is predicted as probably damaging, would alter the conformation of the protein slightly and would cause a decrease of gene expression.
Conclusions: This is the first report of an EGR2 mutation presenting as an axonal CMT phenotype with variable severity. This study broadens the phenotype of the EGR2-related neuropathies and suggests that the genetic testing of patients suffering from axonal CMT should include the EGR2 gene.This collaborative joint project is awarded by IRDiRC and funded by the Instituto de Salud Carlos III (ISCIII) - Subdireccion General de Evaluacion y Fomento de la Investigacion within the framework of the National R+D+I Plan (Grants IR11/TREAT-CMT, PI12/00946 and PI12/00453), co-funded with FEDER funds. C.E. has a "Miguel Servet' contract funded by the ISCIII and Centro de Investigacion Principe Felipe (CIPF) (Grant no. CPII14/00002). We are also grateful to Itziar Llopis for sample management.Sevilla, T.; Sivera, R.; Martínez-Rubio, D.; Lupo, V.; Chumillas, M.; Calpena-Corpas, E.; Dopazo, J.... (2015). The EGR2 gene is involved in axonal Charcot-Marie-Tooth disease. European Journal of Neurology. 22(12):1548-1555. https://doi.org/10.1111/ene.1278215481555221
El clima vitícola de las regiones productoras de uvas para vinos en Cuba.
El clima de Cuba se ha definido como tropical, estacionalmente húmedo, con influencia marítima y rasgos de semicontinentalidad (Köpen, 1907; Iñiguez y Mateo, 1980; Lima et al., 1988; Lecha et al., 1993). De acuerdo con Lima (1992) es tropical modificado por diferentes factores: la configuración alargada del Archipiélago cubano que hace mas efectiva la acción de los vientos alisios del nordeste y la acción reguladora del mar sobre las temperaturas de la costa norte, las corrientes marítimas cálidas que lo bañan, la acción permanente del anticiclón del Atlántico Norte, la proximidad al continente americano y los vientos nortes y sures, entre otros
Sexual selection drives weak positive selection in protamine genes and high promoter divergence, enhancing sperm competitiveness
Phenotypic adaptations may be the result of changes in gene structure or gene regulation, but little is known about the evolution of gene expression. In addition, it is unclear whether the same selective forces may operate at both levels simultaneously. Reproductive proteins evolve rapidly, but the underlying selective forces promoting such rapid changes are still a matter of debate. In particular, the role of sexual selection in driving positive selection among reproductive proteins remains controversial, whereas its potential influence on changes in promoter regions has not been explored. Protamines are responsible for maintaining DNA in a compacted form in chromosomes in sperm and the available evidence suggests that they evolve rapidly. Because protamines condense DNA within the sperm nucleus, they influence sperm head shape. Here, we examine the influence of sperm competition upon protamine 1 and protamine 2 genes and their promoters, by comparing closely related species of Mus that differ in relative testes size, a reliable indicator of levels of sperm competition. We find evidence of positive selection in the protamine 2 gene in the species with the highest inferred levels of sperm competition. In addition, sperm competition levels across all species are strongly associated with high divergence in protamine 2 promoters that, in turn, are associated with sperm swimming speed. We suggest that changes in protamine 2 promoters are likely to enhance sperm swimming speed by making sperm heads more hydrodynamic. Such phenotypic changes are adaptive because sperm swimming speed may be a major determinant of fertilization success under sperm competition. Thus, when species have diverged recently, few changes in gene-coding sequences are found, while high divergence in promoters seems to be associated with the intensity of sexual selection
A critical evaluation of network and pathway based classifiers for outcome prediction in breast cancer
Recently, several classifiers that combine primary tumor data, like gene
expression data, and secondary data sources, such as protein-protein
interaction networks, have been proposed for predicting outcome in breast
cancer. In these approaches, new composite features are typically constructed
by aggregating the expression levels of several genes. The secondary data
sources are employed to guide this aggregation. Although many studies claim
that these approaches improve classification performance over single gene
classifiers, the gain in performance is difficult to assess. This stems mainly
from the fact that different breast cancer data sets and validation procedures
are employed to assess the performance. Here we address these issues by
employing a large cohort of six breast cancer data sets as benchmark set and by
performing an unbiased evaluation of the classification accuracies of the
different approaches. Contrary to previous claims, we find that composite
feature classifiers do not outperform simple single gene classifiers. We
investigate the effect of (1) the number of selected features; (2) the specific
gene set from which features are selected; (3) the size of the training set and
(4) the heterogeneity of the data set on the performance of composite feature
and single gene classifiers. Strikingly, we find that randomization of
secondary data sources, which destroys all biological information in these
sources, does not result in a deterioration in performance of composite feature
classifiers. Finally, we show that when a proper correction for gene set size
is performed, the stability of single gene sets is similar to the stability of
composite feature sets. Based on these results there is currently no reason to
prefer prognostic classifiers based on composite features over single gene
classifiers for predicting outcome in breast cancer
Definition of a list of fish diseases to aid health management in Spain
Trabajo presentado en la 14th EAFP International Conference (European Association of Fish Pathologists), celebrada en Praga (República Checa), del 14 al 19 de septiembre de 2009An expert working group used a risk ranking technique to compile a list of fish disease hazards (pathogens) of relevance to Spanish aquaculture. It was possible to divide the list into three groups: I-high national risk; II-regional risk; III-low risk.
The three groups were as follows:
Group I (high risk)
Aphanomyces invadans (EUS)**, spring viraemia of carp virus (SVCV), koi herpes virus (KHV)¿ and infectious haematopoietic necrosis virus (IHNV)¿
Group II (regional risk)
Enteromyxum spp. (leei and scophthalmi), Aquabirnaviridae (incl. IPNV), viral encephalopathy and retinopathy virus (VERV), Streptococcus iniae, Philasterides dicentrarchi and Aeromonas salmonicida (in the marine environment).
Group III (low risk)
Sparicotyle chrysophrii/Microcotylidae, Flavobacterium maritimus, Photobacterium piscicida, Togaviridae, Sphaerospora testicularis, Edwardsiella tarda, Birnavirus (no-EVE), Lactococcus garviae, viral haemorrhagic septicaemia virus (VHSV)¿, Tenacibaculum maritimum, epizootic haematopoietic necrosis virus (EHNV)**, Renibacterium salmoninarum (BKD) and Gyrodactylus salaris.
The exercise formed part of a project concerning aquaculture health management (Jacumar-GESAC¿) in Spain and is being used to help define sampling plans for disease monitoring using epidemiological and risk-based criteria.
**The diseases caused by these pathogens are notifiable and exotic according to Directive 2006/88/EC
¿The diseases caused by these pathogens are notifiable and non-exotic according to Directive 2006/88/EC
¿Plan Nacional de Cultivos Marinos; Gestión sanitaria de la acuicultura: Adaptación a la nueva normativa (GESAC) ¿ financed by the Junta Nacional Asesora de Cultivos Marinos (Jacumar
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