Search results for "Levi"
showing 10 items of 851 documents
EFFECT OF DELETERIOUS MUTATION-ACCUMULATION ON THE FITNESS OF RNA BACTERIOPHAGE MS2
2000
RNA viruses show the highest mutation rate in nature. It has been extensively demonstrated that, in the absence of purifying selection, RNA viruses accumulate deleterious mutations at a high rate. However, the parameters describing this accumulation are, in general, poorly understood. The present study reports evidences for fitness declines by the accumulation of deleterious mutations in the bacteriophage MS2. We estimated the rate of fitness decline to be as high as 16% per bottleneck transfer. In addition, our results agree with an additive model of fitness effects.
Rapid evolution of translational control mechanisms in RNA genomes
1997
We have introduced 13 base substitutions into the coat protein gene of RNA bacteriophage MS2. The mutations, which are clustered ahead of the overlapping lysis cistron, do not change the amino acid sequence of the coat protein, but they disrupt a local hairpin, which is needed to control translation of the lysis gene. The mutations decreased the phage titer by four orders of magnitude but, upon passaging, the virus accumulated suppressor mutations that raised the fitness to almost wild-type level. Analysis of the pseudorevertants showed that the disruption of the local hairpin, controlling expression of the lysis gene, had apparently been so complete that its restoration by chance mutations…
Forced Retroevolution of an RNA Bacteriophage
2000
AbstractThe operator hairpin ahead of the replicase gene in RNA bacteriophage MS2 contains overlapping signals for binding the coat protein and ribosomes. Coat protein binding inhibits further translation of the gene and forms the first step in capsid formation. The hairpin sequence was partially randomized to assess the importance of this structure element for the bacteriophage and to monitor alternative solutions that would evolve on the passaging of mutant phages. The evolutionary reconstruction of the operator failed in the majority of mutants. Instead, a poor imitation developed containing only some of the recognition signals for the coat protein. Three mutants were of particular inter…
Tracking of Television Viewing Time during Adulthood: The Young Finns Study.
2016
Purpose: The aim of this study was to investigate the tracking of television viewing (TV) time as an indicator of sedentary behavior among adults for a period of 25 yr. Methods: A random sample of 1601 subjects (740 men) age 18, 21, and 24 yr participated in the Cardiovascular Risk in Young Finns Study in 1986. TV time during leisure time was measured with a single self-report question at baseline and in 2001, 2007, and 2011. Tracking of TV time was analyzed using Spearman rank correlations and simplex models. Level and change of TV time were examined using linear growth modeling. Results: The 4- and 6-yr integrated TV time stability coefficients, adjusted for measurement errors, were Q0.60…
The role of family-related factors in the effects of the UP4FUN school-based family-focused intervention targeting screen time in 10- to 12-year-old …
2014
Background Screen-related behaviours are highly prevalent in schoolchildren. Considering the adverse health effects and the relation of obesity and screen time in childhood, efforts to affect screen use in children are warranted. Parents have been identified as an important influence on children’s screen time and therefore should be involved in prevention programmes. The aim was to examine the mediating role of family-related factors on the effects of the school-based family-focused UP4FUN intervention aimed at screen time in 10- to 12-year-old European children (n child–parent dyads = 1940). Methods A randomised controlled trial was conducted to test the six-week UP4FUN intervention in 10-…
LA GOUVERNANCE MUTUALISTE COMME LEVIER DE CONTROLE
2012
The knowledge governance studies the way the administrators can limit the actions of the leaders otherwise than by disciplinary mechanisms. The study of the strategic process is a means to analyze more finely these mechanisms. The results indicate that the elected representatives participate actively in the definition of the strategy of their territory and it through several complementary control levers. Diagnostic and interactive levers are pointed out.
To Be Continued: Serial Narration, Chronic Disease, and Disability.
2019
This article explores the representation of Michael J. Fox's Parkinson's disease in the television series The Good Wife and The Michael J. Fox Show. We suggest that serial narration offers intriguing ways to rethink the function and meaning of narratives in health contexts, and that the episodic narrative form of television series may afford insights into the structure of medical encounters. Specifically, we examine to what extent serial narration, with its focus on continuity and repetition, might help reimagine the typical narrative of decline, which is implicit in the terminology of neurodegeneration, as well as the narrative of (premature) closure or finitude that often accompanies a di…
Irak: una lectura dialógica
2006
Toward a scientific and personal biography of Tullio Levi-Civita (1873–1941)
2005
International audience; Tullio Levi-Civita was one of the most important Italian mathematicians in the early part of the 20th century, contributing significantly to a number of research fields in mathematics and physics. In addition, he was involved in the social and political life of his time and suffered severe political and racial persecution during the period of Fascism. He tried repeatedly and in several cases successfully to help colleagues and students who were victims of anti-Semitism in Italy and Germany. His scientific and private life is well documented in the letters and documents contained in his Archive. The authors' aim is to illustrate the events of his life by means of his …
Ficción audiovisual y procesos de percepción en estudiantes universitarios de Argentina y España. Una investigación empírica. S
2014
Esta investigación descubre las diferencias en la percepción audiovisual en jóvenes estudiantes, mediante la evaluación del impacto afectivo o cambio de estado de ánimo que muestra el observador en relación con un capítulo de una ficción audiovisual conocida. Un grupo de estudiantes de Ciencias de la Comunicación procedentes de la Universidad Austral de Buenos Aires (Argentina) y de la Universidad de Valencia (España) se han sometido a cuestionarios analíticos pre-test y post-test sobre un capítulo de la serie de ficción “The Walking Dead”.