Search results for "POPULATIONS"
showing 10 items of 493 documents
A PHENOMENOLOGICAL OPERATOR DESCRIPTION OF INTERACTIONS BETWEEN POPULATIONS WITH APPLICATIONS TO MIGRATION
2013
We adopt an operatorial method based on the so-called creation, annihilation and number operators in the description of different systems in which two populations interact and move in a two-dimensional region. In particular, we discuss diffusion processes modeled by a quadratic hamiltonian. This general procedure will be adopted, in particular, in the description of migration phenomena. With respect to our previous analogous results, we use here fermionic operators since they automatically implement an upper bound for the population densities.
Ancient human genomes suggest three ancestral populations for present-day Europeans
2014
We sequenced the genomes of a ∼7,000-year-old farmer from Germany and eight ∼8,000-year-old hunter-gatherers from Luxembourg and Sweden. We analysed these and other ancient genomes1,2,3,4 with 2,345 contemporary humans to show that most present-day Europeans derive from at least three highly differentiated populations: west European hunter-gatherers, who contributed ancestry to all Europeans but not to Near Easterners; ancient north Eurasians related to Upper Palaeolithic Siberians3, who contributed to both Europeans and Near Easterners; and early European farmers, who were mainly of Near Eastern origin but also harboured west European hunter-gatherer related ancestry. We model these popula…
COMPARATIVE STUDY OF DIFFERENT POPULATIONS OF OREGANO (ORIGANUM VULGARE SSP. HIRTUM) FOUND IN SICILY
2012
Oregano (Origanum vulgare ssp. hirtum) is one of the most popular aromatic species used in Mediterranean cuisine. In addition to its use for culinary and ornamental purposes, it is also known as a medicinal plant for its antispasmodic, antioxidant, antibacterial, antifungal and expectorant properties. A number of wild oregano populations were found in various areas of Sicily. Representative samples of the different populations at flowering stage were collected at varying altitudes between 60 and 1000 m a.s.l. in 2004 an 2005. The samples were processed to evaluate the quantity and quality of the production, as well as the essential oil composition. Significant differences were found between…
Valorizzazione produttiva della biodiversità in ambiente mediterraneo: il genere Hypericum
2014
Una conoscenza approfondita delle specie appartenenti al genere Hypericum, finalizzata alla loro introduzione negli ordinamenti colturali come specie di interesse industriale e/o ornamentale, comporta la dettagliata descrizione dei parametri morfologici e ambientali delle piante nei loro siti di vegetazione spontanea, e l’accertamento delle loro caratteristiche fitochimiche. Negli anni 2012-2013 è stata svolta un’attività di ricognizione a tale scopo. In Sicilia le perlustrazioni svolte hanno portato all'individuazione di 23 accessioni di H. perforatum, H. perfoliatum, H. pubescens, H. tetrapterum e H. calycinum; numerose altre se ne sono aggiunte, provenienti dall’appennino tosco-romagnolo…
The Emerging Role of the Endocannabinoid System in Endocrine Regulation and Energy Balance
2005
During the last few years, the endocannabinoid system has emerged as a highly relevant topic in the scientific community. Many different regulatory actions have been attributed to endocannabinoids, and their involvement in several pathophysiological conditions is under intense scrutiny. Cannabinoid receptors, named CB1 receptor and CB2 receptor, first discovered as the molecular targets of the psychotropic component of the plant Cannabis sativa, participate in the physiological modulation of many central and peripheral functions. CB2 receptor is mainly expressed in immune cells, whereas CB1 receptor is the most abundant G protein-coupled receptor expressed in the brain. CB1 receptor is expr…
Specific Detection and Localization of Microsporidian Parasites in Invertebrate Hosts by Using In Situ Hybridization
2013
ABSTRACT We designed fluorescence in situ hybridization probes for two distinct microsporidian clades and demonstrated their application in detecting, respectively, Nosema / Vairimorpha and Dictyoceola species. We used them to study the vertical transmission of two microsporidia infecting the amphipod Gammarus duebeni .
Co-occurrence of resonant activation and noise-enhanced stability in a model of cancer growth in the presence of immune response.
2006
We investigate a stochastic version of a simple enzymatic reaction which follows the generic Michaelis-Menten kinetics. At sufficiently high concentrations of reacting species, the molecular fluctuations can be approximated as a realization of a Brownian dynamics for which the model reaction kinetics takes on the form of a stochastic differential equation. After eliminating a fast kinetics, the model can be rephrased into a form of a one-dimensional overdamped Langevin equation. We discuss physical aspects of environmental noises acting in such a reduced system, pointing out the possibility of coexistence of dynamical regimes where noise-enhanced stability and resonant activation phenomena …
Solving NP-Complete Problems with Networks of Evolutionary Processors
2001
We propose a computational device based on evolutionary rules and communication within a network, similar to that introduced in [4], called network of evolutionary processors. An NP-complete problem is solved by networks of evolutionary processors of linear size in linear time. Some furher directions of research are finally discussed.
Le son et le pouvoir en Bourgogne au XVe siècle
2000
Place: Paris Publisher: PUF
La musique dans et hors de la cathédrale : fête des fous et carnavals en Bourgogne à la fin du Moyen Age
2000
dir. Micheline Durand et Laura Weigert; International audience