Search results for "Causa"
showing 10 items of 661 documents
Mother and offspring fitness in an insect with maternal care: phenotypic trade-offs between egg number, egg mass and egg care
2014
Background Oviparous females have three main options to increase their reproductive success: investing into egg number, egg mass and/or egg care. Although allocating resources to either of these three components is known to shape offspring number and size, potential trade-offs among them may have key impacts on maternal and offspring fitness. Here, we tested the occurrence of phenotypic trade-offs between egg number, egg mass and maternal expenditure on egg care in the European earwig, Forficula auricularia, an insect with pre- and post-hatching forms of maternal care. In particular, we used a series of laboratory observations and experiments to investigate whether these three components no…
Oral lichenoid disease as a premalignant condition : the controversies and the unknown
2009
We grouped as oral lichenoid disease (OLD) a series of chronic inflammatory processes with autoimmune base that affect the epithelium of the oral mucosa. This disease presents in 2% of the population with a marked predilection for the female gender, especially perimenopausal women. Clinically, it is characterized by the presence of lineal reticular papules and histologically by liquefaction degeneration of the basal layer of the epithelium associated with an inflammatory infiltrate with a "band-like" disposition on the lamina propria, composed primarily of T lymphocyte cells. Its pathogenicity is associated with deregulation of the cellular immune system, where the activated cytotoxic CD8 a…
Paracetamol and antibiotics in childhood and subsequent development of wheezing/asthma: association or causation?
2011
Background Several studies found an association between early administration of paracetamol and antibiotics and development of wheezing. This could be due to confounding: wheeze and asthmatic symptoms in early childhood are difficult to distinguish from respiratory tract infections that are widely treated with these drugs; in case of persistence of symptoms up to school age, this could explain the observed relationship. Methods We investigated the association between paracetamol and antibiotics use in the first year of life and wheezing phenotypes, i.e. wheezing starting in different time periods (early, persistent and late-onset) in the SIDRIA-2 study, a cross-sectional survey of 16,933 ch…
Avis de l'Anses relatif à l'actualisation de la méthode d'imputabilité des signalements d'effets indésirables de nutrivigilance
2019
A l’instar des autres systèmes de vigilance français et compte tenu de l’importance des conséquences en matière de santé et des décisions industrielles qui en découlent, l’analyse de la relation de causalité entre un produit visé par le dispositif national de nutrivigilance et l’effetindésirable déclaré doit être réalisée avec une méthode d’analyse appropriée et objective. Cette méthode dite « méthode d’imputabilité de nutrivigilance » estime le degré de causalité, d’un ou de plusieurs produits dans la survenue de l’effet indésirable déclaré, de manière standardisée, permettant d’éliminer les divergences d’opinion pouvant exister entre plusieurs observateurs. De telles méthodes sont couramm…
How does academic achievement come about: cross-cultural and methodological notes
2001
Abstract This chapter discusses the possible impact of cross-national diversity in academic institutions, in the selection of students, in the importance of national achievement tests, and cross-national differences in the variation of social background factors. It ends with the strengths and limitations of using path modeling in cross-sectional research. It is of particular interest to note whether study behaviors mediate the impact of students’ abilities on college success, or whether students’ abilities mediate the effect of study behaviors on achievement. A secondary concern is the extent to which the same causal model applies equally to different universities in different countries.
Estimation of Granger causality through Artificial Neural Networks: applications to physiological systems and chaotic electronic oscillators
2021
One of the most challenging problems in the study of complex dynamical systems is to find the statistical interdependencies among the system components. Granger causality (GC) represents one of the most employed approaches, based on modeling the system dynamics with a linear vector autoregressive (VAR) model and on evaluating the information flow between two processes in terms of prediction error variances. In its most advanced setting, GC analysis is performed through a state-space (SS) representation of the VAR model that allows to compute both conditional and unconditional forms of GC by solving only one regression problem. While this problem is typically solved through Ordinary Least Sq…
Time-dependent Kohn-Sham approach to quantum electrodynamics
2010
We prove a generalization of the van Leeuwen theorem towards quantum electrodynamics, providing the formal foundations of a time-dependent Kohn-Sham construction for coupled quantized matter and electromagnetic fields. Thereby we circumvent the symmetry-causality problems associated with the action-functional approach to Kohn-Sham systems. We show that the effective external four-potential and four-current of the Kohn-Sham system are uniquely defined and that the effective four-current takes a very simple form. Further we rederive the Runge-Gross theorem for quantum electrodynamics.
Spectral decomposition of cerebrovascular and cardiovascular interactions in patients prone to postural syncope and healthy controls.
2022
We present a framework for the linear parametric analysis of pairwise interactions in bivariate time series in the time and frequency domains, which allows the evaluation of total, causal and instantaneous interactions and connects time- and frequency-domain measures. The framework is applied to physiological time series to investigate the cerebrovascular regulation from the variability of mean cerebral blood flow velocity (CBFV) and mean arterial pressure (MAP), and the cardiovascular regulation from the variability of heart period (HP) and systolic arterial pressure (SAP). We analyze time series acquired at rest and during the early and late phase of head-up tilt in subjects developing or…
Evaluating the Interrelationship between Actions of Latvian Commercial Banks and Latvian Economic Growth
2017
Abstract This paper aims to evaluate the existence of the interrelationship between Latvian commercial banks’ operations on the economy, based on economic theory and the analysis of banks’ retained earnings, credit growth and economic growth trends. The existence of this interrelationship was tested using Granger causality and Johansen co integration tests. The analysis was based on quarterly data from 2001 to 2015. The study reviewed several indicators for banking developments to establish their relevance for GDP growth: credit to non-banks, non-bank deposits and bank retained earnings. This paper finds that the empirical link between bank retained earnings and GDP growth is more robust th…
Fibre Bundle for Spin and Charge in General Relativity
2000
The Lorentzian and spin structures of general relativity are shown to allow a natural extension, by means of which the set of possible electromagnetic bundles is linked to the topology and geometry of the underlying causal structure. Further, both the Dirac operator and the electromagnetic potential are obtainable from a single linear connection 1-form.