Discourse-sensitive clitic-doubled dislocations in heritage Spanish

This experimental study tests the predictions of the Interface Hypothesis (Sorace, 2011, 2012) using two constructions whose appropriateness depends on monitoring discourse information: Clitic Left Dislocation and Fronted Focus. Clitic Left Dislocation relates a dislocated and clitic-doubled object to an antecedent activated in previous discourse, while Fronted Focus does not relate the fronted constituent to a discourse antecedent. The Interface Hypothesis argues that speakers in language contact situations experience difficulties when they have to integrate syntactic with discourse information. We tested four groups of native speakers on these constructions: Spanish monolinguals, bilinguals with more than 7 years residence in the US, intermediate and advanced proficiency heritage speakers. Our findings suggest that attrition has not set in the adult L2 bilingual speakers, and that the heritage speakers perform similarly to the monolingual and the adult sequential bilingual natives.

Stress relaxation behaviour of frozen sucrose solutions

The stress relaxation behaviour of two frozen sucrose solutions (7% and 19%) during indentation in the temperature range of -20C to -40C were investigated. The stress relaxation is similar to that of pure polycrystalline ice, which is controlled by steady-state creep. The steady state creep rate exponent, m, of 7% and 19% sucrose solutions lies between 2.3 and 3.6. The steady state creep rate constant, B, of 19% sucrose solution is greater than that of 7% sucrose solution. It is suggested that the steady-state creep rate exponent m depends on contributions from the proportions of favourably oriented grains, unfavourably oriented grains and grain boundaries to creep and that these components depend on the value of internal stress which is related to the hardness of samples at the different testing temperatures. The steady-state creep rate constant B depends on the mobility of dislocations in sucrose solutions which, in turn, depends on the temperature and the concentration of sucrose.

Dislocazioni

Encyclopedia entry on "dislocations" in language

Simulating metals and mine discharges in river basins using a new integrated catchment model for metals: pollution impacts and restoration strategies in the Aries-Mures river system in Transylvania, Romania

The INtegrated CAtchment (INCA) model has been developed to simulate the impact of mine discharges on river systems. The model accounts for the key kinetic chemical processes operating as well as the dilution, mixing and redistribution of pollutants in rivers downstream of mine discharges or acid rock drainage sites. The model is dynamic and simulates the day-to-day behaviour of hydrology and eight metals (cadmium, mercury, copper, zinc, lead, arsenic, manganese and chromium) as well as cyanide and ammonia. The model is semi-distributed and can simulate catchments, sub-catchment and in-stream river behaviour. The model has been applied to the Roia Montan Mine in Transylvania, Romania, and used to assess the impacts of old mine adits on the local catchments as well as on the downstream Aries and Mures river system. The question of mine restoration is investigated and a set of clean-up scenarios investigated. It is shown that the planned restoration will generate a much improved water quality from the mine and also alleviate the metal pollution of the river system.

The effect of organic materials on the mobility and toxicity of metals in contaminated soils

Organic materials such as compost are often proposed as suitable materials for the remediation of contaminated brownfield sites intended for soft end-use. In addition to vitalising the soil, they are also believed to immobilise metals thereby breaking contaminant-receptor pathways and reducing the ecotoxicity of the contaminants. However, some research has demonstrated contradictory effects between composts on metal immobilisation. In the present study, four different composts and a liming product containing organic matter (LimeX70) were tested to examine both their metal retention and toxicity reduction capabilities on three different metal contaminated soils. Leaching tests, a plant growth test with Greek cress (Lepidium sativum), an earthworm (Eisenia fetida) survival and condition test and a bacterial toxicity test using Vibrio fischeri were carried out. The leaching test results showed that spent mushroom compost caused an increase in metal concentration in the leachates, while LimeX70 caused a decrease. The variation in behaviour between different amendments for each soil was high, so a generic conclusion could not be drawn. Toxicity tests showed significant reduction of metal bioavailability and toxicity for Greek cress, earthworms and bacteria. The results also suggest that more research should be undertaken to understand the mechanisms involved in metal complexation using different types of organic matter, in order to optimise the use of organic materials like compost for soil remediation. Crown Copyright (C) 2007 Published by Elsevier Ltd. All rights reserved.

Influence of dissolved organic matter on the solubility of heavy metals in sewage-sludge-amended soils

Sewage-sludge-amended soils generally contain elevated levels of organic matter and heavy metals compared to control soils. Because organic matter is known to complex with heavy metals, the solubility behavior of the organic matter in such soils may exert a significant influence on the solubility of the metals. Little is known about such a process. Using batch experiments in which the solubility of organic matter in a heavily sludge-amended soil was artificially manipulated, we show that the solubilities of the heavy metals copper (Cu), nickel (Ni), and lead (Pb) show a strong positive relationship to the solubility of organic matter, particularly at high pH. The results suggest that under field conditions, spatiotemporal variations in the solid-solution partitioning of organic matter may have a bearing on the environmental significance (mobility and bioavailability) of these heavy metals.

Distribution of selected heavy metals in sediments of the Agueda river (Central Portugal)

The state of river water deterioration in the Agueda hydrographic basin, mostly in the western part, partly reflects the high rate of housing and industrial development in this area in recent years. The streams have acted as a sink for organic and inorganic loads from several origins: domestic and industrial sewage and agricultural waste. The contents of the heavy metals Cr, Cd, Ni, Cu, Pb, and Zn were studied by sequential chemical extraction of the principal geochemical phases of streambed sediments, in the <63 mum fraction, in order to assess their potential availability to the environment, investigating, the metal concentrations, assemblages, and trends. The granulometric and mineralogical characteristics of this sediment fraction were also studied. This study revealed clear pollution by Cr, Cd, Ni, Cu, Zn, and Pb, as a result from both natural and anthropogenic origins. The chemical transport of metals appears to be essentially by the following geochemical phases, in decreasing order of significance: (exchangeable + carbonates) much greater than (organics) much greater than (Mn and Fe oxides and hydroxides). The (exchangeable + carbonate) phase plays an important part in the fixation of Cu, Ni, Zn, and Cd. The organic phase is important in the fixation of Cr, Pb, and also Cu and Ni. Analyzing the metal contents in the residual fraction, we conclude that Zn and Cd are the most mobile, and Cr and Pb are less mobile than Cu and Ni. The proximity of the pollutant sources and the timing of the influx of contaminated material control the distribution of the contaminant-related sediments locally and on the network scale.

An inventory of heavy metals inputs to agricultural soils in England and Wales

An inventory of heavy metal inputs (Zn, Cu, Ni, Pb, Cd, Cr, As and Hg) to agricultural soils in England and Wales in 2000 is presented, accounting for major sources including atmospheric deposition, sewage sludge, livestock manures, inorganic fertilisers and lime, agrochemicals, irrigation water, industrial by-product 'wastes' and composts. Across the whole agricultural land area, atmospheric deposition was the main source of most metals, ranging from 25 to 85% of total inputs. Livestock manures and sewage sludge were also important sources, responsible for an estimated 37-40 and 8-17% of total Zn and Cu inputs, respectively. However, at the individual field scale sewage sludge, livestock manures and industrial wastes could be the major source of many metals where these materials are applied. This work will assist in developing strategies for reducing heavy metal inputs to agricultural land and effectively targeting policies to protect soils from long-term heavy metal accumulation. (C) 2003 Elsevier Science B.V. All rights reserved.

The effect of organic materials on the mobility and toxicity of metals in contaminated soils

Organic materials such as compost are often proposed as suitable materials for the remediation of contaminated brownfield sites intended for soft end-use. In addition to vitalising the soil, they are also believed to immobilise metals thereby breaking contaminant-receptor pathways and reducing the ecotoxicity of the contaminants. However, some research has demonstrated contradictory effects between composts on metal immobilisation. In the present study, four different composts and a liming product containing organic matter (LimeX70) were tested to examine both their metal retention and toxicity reduction capabilities on three different metal contaminated soils. Leaching tests, a plant growth test with Greek cress (Lepidium sativum), an earthworm (Eisenia fetida) survival and condition test and a bacterial toxicity test using Vibrio fischeri were carried out. The leaching test results showed that spent mushroom compost caused an increase in metal concentration in the leachates, while LimeX70 caused a decrease. The variation in behaviour between different amendments for each soil was high, so a generic conclusion could not be drawn. Toxicity tests showed significant reduction of metal bioavailability and toxicity for Greek cress, earthworms and bacteria. The results also suggest that more research should be undertaken to understand the mechanisms involved in metal complexation using different types of organic matter, in order to optimise the use of organic materials like compost for soil remediation. Crown Copyright (C) 2007 Published by Elsevier Ltd. All rights reserved.

Expression of metallothionein genes I and II in bank vole clethrionomys glareolus populations chronically exposed in situ to heavy metals

The expression of two metallothionein genes (Mt-I and Mt-II) in the liver, kidney, and gonad of bank voles collected at four metal-contaminated sites (Cd, Zn, Pb, and Fe) were measured using the quantitative real-time PCR method (QPCR). Relative Mt gene expression was calculated by applying a normalization factor (NF) using the expression of two housekeeping genes, ribosomal 18S and beta-actin. Relative Mt expression in tissues of animals from contaminated sites was up to 54.8-fold higher than those from the reference site for Mt-I and up to 91.6-fold higher for Mt-II. Mt-II gene expression in the livers of bank voles from contaminated sites was higher than Mt-I gene expression. Inversely, Mt-II expression in the kidneys of voles was lower than Mt-I expression. Positive correlations between cadmium levels in the tissues and Mt-I were obtained in all studied tissues. Zinc, which undergoes homeostatic regulation, correlated positively with both Mt-I and Mt-II gene expression only in the kidney. Results showed that animals living in chronically contaminated environments intensively activate detoxifying mechanisms such as metallothionein expression. This is the first time that QPCR techniques to measure MT gene expression have been applied to assess the impact of environmental metal pollution on field collected bank voles.

Free radicals, metals and antioxidants in oxidative stress-induced cancer

Oxygen-free radicals, more generally known as reactive oxygen species (ROS) along with reactive nitrogen species (RNS) are well recognised for playing a dual role as both deleterious and beneficial species. The "two-faced" character of ROS is substantiated by growing body of evidence that ROS within cells act as secondary messengers in intracellular signalling cascades, which induce and maintain the oncogenic phenotype of cancer cells, however, ROS can also induce cellular senescence and apoptosis and can therefore function as anti-tumourigenic species. The cumulative production of ROS/RNS through either endogenous or exogenous insults is termed oxidative stress and is common for many types of cancer cell that are linked with altered redox regulation of cellular signalling pathways. Oxidative stress induces a cellular redox imbalance which has been found to be present in various cancer cells compared with normal cells; the redox imbalance thus may be related to oncogenic stimulation. DNA mutation is a critical step in carcinogenesis and elevated levels of oxidative DNA lesions (8-OH-G) have been noted in various tumours, strongly implicating such damage in the etiology of cancer. It appears that the DNA damage is predominantly linked with the initiation process. This review examines the evidence for involvement of the oxidative stress in the carcinogenesis process. Attention is focused on structural, chemical and biochemical aspects of free radicals, the endogenous and exogenous sources of their generation, the metal (iron, copper, chromium, cobalt, vanadium, cadmium, arsenic, nickel)-mediated formation of free radicals (e.g. Fenton chemistry), the DNA damage (both mitochondrial and nuclear), the damage to lipids and proteins by free radicals, the phenomenon of oxidative stress, cancer and the redox environment of a cell, the mechanisms of carcinogenesis and the role of signalling cascades by ROS; in particular. ROS activation of AP-1 (activator protein) and NF-kappa B (nuclear factor kappa B) signal transduction pathways, which, in turn lead to the transcription of genes involved in cell growth regulatory pathways. The role of enzymatic (superoxide dismutase (Cu. Zn-SOD. Mn-SOD), catalase, glutathione peroxidase) and non-enzymatic antioxidants (Vitamin C, Vitamin E, carotenoids, thiol antioxidants (glutathione, thioredoxin and lipoic acid), flavonoids, selenium and others) in the process of careinogenesis as well as the antioxidant interactions with various regulatory factors, including Ref-1, NF-kappa B, AP-1 are also reviewed. 2006 Elsevier Ireland Ltd. All rights reserved.

Sampling and analyzing metals in soils for archaeological prospection: a critique

This paper presents a critique of current methods of sampling and analyzing soils for metals in archaeological prospection. Commonly used methodologies in soil science are shown to be suitable for archaeological investigations, with a concomitant improvement in their resolution. Understanding the soil-fraction location, concentration range, and spatial distribution of autochthonous (native) soil metals is shown to be a vital precursor to archaeological-site investigations, as this is the background upon which anthropogenic deposition takes place. Nested sampling is suggested as the most cost-effective method of investigating the spatial variability in the autochthonous metal concentrations. The use of the appropriate soil horizon (or sampling depth) and point sampling are critical in the preparation of a sampling regime. Simultaneous extraction is proposed as the most efficient method of identifying the location and eventual fate of autochthonous and anthropogenic metals, respectively.