Search results for "HETEROGENEITY"
showing 10 items of 402 documents
Studies of intermolecular heterogeneity distribution in ethylene/1-hexene copolymers using DSC method
2002
The investigation of the intermolecular composition distribution of an ethylene/1-hexene copolymers using DSC method has been carried out. The known methods: step crystallization (SC) and successive self-nucleation/annealing (SSA) have been adapted for this purpose, and particularly, the optimal condition of the process have been chosen to enable the best fractional crystallization of the copolymer. The method has been applied for fractionation of two ethylene/1-hexenecopolymers synthesized with supported vanadium and zirconocene catalysts and having similar concentrations of 1-hexene. Although metallocene catalysts are known from their more homogeneous structure of active sites in comparis…
Population genetic structure of aposematic alpine wood tiger moths (Parasemia plantaginis)
2012
Alpine landscape with natural fragmentation restricts gene flow among populations and causes spatio-genetic structuring (high genetic differentiation) in species living there. Consequently, alpine habitat fragmentation and dispersal barriers should make isolated populations such as wood tiger moth (Parasemia plantaginis) populations prone to lose genetic diversity by local adaptation and fixation of fittest phenotype in each local population. This species is also known to be aposematic. Yellow colour on the males’ hind wings in wood tiger moth is presumed to work more efficiently against visual hunting predators due to increased conspicuousness. In addition, in field experiments with wood t…
Effect of restoration on zooplankton community in a permanent interdunal pond
2013
Restoration projects in wetlands are becoming increasingly frequent to recover or to create new aquatic ecosystems, after the significant impact and high degradation they have undergone. In the present study, we focused on the changes in the zooplankton community in a permanent peridunal pond where a restoration was carried out in order to increase its surface as a main objective. For this purpose, the community was compared before and after the restoration (15 years before, the year after and between 3 and 6 years later). Significant changes in environmental variables were observed after pond restoration: chlorophyll a concentration decreased and dissolved oxygen increased. Substantial mod…
Melt extraction and accumulation from partially molten rocks
2004
Current models for melt segregation and ascent are not adequate to accurately describe transport and accumulation in combination. We propose that transport is discontinuous and in batches, and that accumulation occurs by stepwise merging of batches. A simple numerical model of jostling spheres that merge when they touch was used to represent stepwise accumulation and transport of batches by propagation of hydrofractures. Results of the numerical model indicate that such a system may quickly develop into a self-organised critical (SOC) state. In this state, the distribution of melt batch volumes can be described by a power law, with an exponent m that lies between 2/3 and 1. Once a self-orga…
The internationalisation of the Spanish food industry: the home market effect and European market integration
2015
<p>The objective of this study was to analyse, from a long-term perspective, the factors determining the process of the internationalisation of the Spanish agrifood industry. The paper concentrates on the empirical verification of the existence of a home market effect in the food and drink industries in Spain and on the effects on trade flows of integration into the European Union. With this aim in mind, we took into account the latest contributions to the estimation of the gravity equation for a sample of export flows from 13 agrifood subsectors between 1970 and 2012, with a destination of 175 markets. From the results of the study the existence of the “home market effect” stands out…
Hydraulic Habitat Structure Impacts Risk of Trematode Infection
2022
Abstract— Variability in infection rates of trematodes Diplostomum pseudospathaceum in 0+ rainbow trout Oncorhynchus mykiss under different hydraulic regimes was studied in the experimental setup with regulated flow rates and environmental heterogeneity. The average infection rate in the conditions of the current was 1.5 times less than that in the stagnant water. An increase of the flow rate from 3.2 to 11.3 cm/s did not result in lower infection rates, while the interindividual variability in the infection rate (coefficient of variation) tended to increase along with changing the still-water conditions (20%) to the high flow rate environments (40%) within the experiment. A decrease in th…
Molecular Pathways Implicated in Radioresistance of Glioblastoma Multiforme: What Is the Role of Extracellular Vesicles?
2023
Glioblastoma multiforme (GBM) is a primary brain tumor that is very aggressive, resistant to treatment, and characterized by a high degree of anaplasia and proliferation. Routine treatment includes ablative surgery, chemotherapy, and radiotherapy. However, GMB rapidly relapses and develops radioresistance. Here, we briefly review the mechanisms underpinning radioresistance and discuss research to stop it and install anti-tumor defenses. Factors that participate in radioresistance are varied and include stem cells, tumor heterogeneity, tumor microenvironment, hypoxia, metabolic reprogramming, the chaperone system, non-coding RNAs, DNA repair, and extracellular vesicles (EVs). We direct our a…
Matching heterogeneous job seekers and vacancies : empirical studies using Finnish data
2006
O Brasil na rota das migrações internacionais qualificadas espanholas no século XXI
2018
In order to understand recent migration, it is crucial to analyze the migratory modalities such as skilled international migration to Brazil, especially considering the ongoing transnational economic processes and their effects on the corresponding societies. Therefore, this article seeks to understand how the migratory dynamics of highly skilled Spanish professionals to the country are established taking into account the theoretical contribution of the circulation of brains and the category of knowledge workers. For this purpose, information from Brazilian?s Ministry of Labor is used on labor authorizations, financial contributions and insertion in the formal market in Spain; as well as da…