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Significant Presence (significant + presence)
Selected AbstractsHepatotoxic cyanobacterial blooms in the lakes of northern PolandENVIRONMENTAL TOXICOLOGY, Issue 5 2005Joanna Mankiewicz Abstract The lakes of northern Poland are among the recreational sites most valued by Polish and German holiday makers. Given the socioeconomic importance of these lakes, water quality should be maintained at high levels for such intensive recreational purposes. In 2002 studies of species composition, biomass, and toxin production by phytoplankton and the attendant physicochemical variables were performed in order to assess the risk of cyanobacterial blooms in selected northern lakes: Lakes Jeziorak, Jagodne, Szymoneckie, Szymon, Taltowisko, Siecino, and Trzesiecko. The research showed that total phosphorus (0.1 mg P/L) and total nitrogen (1.5 mg N/L) in the studied lakes almost exceeded the permissible limits for eutrophication of water bodies. Most phytoplankton samples were taken in late summer, when cyanobacteria were expected to reach their highest biomass. At the time of sampling most of the lakes were dominated by oscillatorialean and nostocalean species. Average chlorophyll-a concentration was higher than 10 ,g/L in almost all the lakes studied, which corresponded with an average microcystin concentration in the range of 4,5 ,g/L. The main microcystins in the analyzed samples were dmMC-RR, MC-RR, MC-YR, and MC-LR. The results demonstrated a potential for intensive cyanobacterial blooms to appear during the summer in northern Polish lakes. The levels of cyanobacteria found in the lakes investigated indicated that toxicity had reached the first-alert level according to World Health Organization recommendations. If microcystin-producing cyanobacteria dominate, with a microcystin concentration of 2,4 ,g/L, symptoms of toxicity can appear in the swimmers most sensitive to exposure. Analysis of cyanobacterial assemblages in northern Polish lakes also indicated a significant presence of Aphanizomenon species including a Scandinavian species, A. skujae (Skuja) Kom.-Legn. & Cronb. Future investigations of Polish lakes also should assess neurotoxins and study the biology of their producers. This study was the first attempt to evaluate the potential danger of toxic cyanobacterial blooms in the lakes of northern Poland. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 499,506, 2005. [source] Cannabinoid CB2 receptor agonists protect the striatum against malonate toxicity: Relevance for Huntington's diseaseGLIA, Issue 11 2009Onintza Sagredo Abstract Cannabinoid agonists might serve as neuroprotective agents in neurodegenerative disorders. Here, we examined this hypothesis in a rat model of Huntington's disease (HD) generated by intrastriatal injection of the mitochondrial complex II inhibitor malonate. Our results showed that only compounds able to activate CB2 receptors were capable of protecting striatal projection neurons from malonate-induced death. That CB2 receptor agonists are neuroprotective was confirmed by using the selective CB2 receptor antagonist, SR144528, and by the observation that mice deficient in CB2 receptor were more sensitive to malonate than wild-type animals. CB2 receptors are scarce in the striatum in healthy conditions, but they are markedly upregulated after the lesion with malonate. Studies of double immunostaining revealed a significant presence of CB2 receptors in cells labeled with the marker of reactive microglia OX-42, and also in cells labeled with GFAP (a marker of astrocytes). We further showed that the activation of CB2 receptors significantly reduced the levels of tumor necrosis factor-, (TNF-,) that had been increased by the lesion with malonate. In summary, our results demonstrate that stimulation of CB2 receptors protect the striatum against malonate toxicity, likely through a mechanism involving glial cells, in particular reactive microglial cells in which CB2 receptors would be upregulated in response to the lesion. Activation of these receptors would reduce the generation of proinflammatory molecules like TNF-,. Altogether, our results support the hypothesis that CB2 receptors could constitute a therapeutic target to slowdown neurodegeneration in HD. © 2008 Wiley-Liss, Inc. [source] Becoming Sinless: Converting to Islam in the Christian Solomon IslandsAMERICAN ANTHROPOLOGIST, Issue 4 2009Debra McDougall ABSTRACT Islam is beginning to have a significant presence in the predominantly Christian nation of Solomon Islands. A few well-educated Islanders were drawn to Islam's elegant monotheism and promise of unity in the 1980s and early 1990s, but numbers have grown significantly in the years following a violent civil conflict (1998,2003). Many of these new Muslim converts, especially those from the island of Malaita, seem preoccupied with the problem of sin and blame Christianity for destroying customary rules, especially those enforcing gender segregation. Echoing long-standing Malaitan critiques of Christian freedom, they say that Christians rely too heavily on God's grace and their own ability to resist temptation. Unlike Christianity and similar to the traditional religion of the islands, Islam provides clear moral rules for living. Seeking an escape from a cycle of sin and redemption, these ex-evangelical Christians now see in Islam the possibility of becoming sinless. [source] Red star-forming and blue passive galaxies in clustersMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009Smriti Mahajan ABSTRACT We explore the relation between colour (measured from photometry) and specific star formation rate (derived from optical spectra obtained by the Sloan Digital Sky Survey Data Release 4) of over 6000 galaxies (Mr,,20.5) in and around (<3 r200) low-redshift (z < 0.12) Abell clusters. Even though, as expected, most red sequence galaxies have little or no ongoing star formation, and most blue galaxies are currently forming stars, there are significant populations of red star-forming and blue passive galaxies. This paper examines various properties of galaxies belonging to the latter two categories, to understand why they deviate from the norm. These properties include morphological parameters, internal extinction, spectral features such as EW(H,) and the 4000 Å break, and metallicity. Our analysis shows that the blue passive galaxies have properties very similar to their star-forming counterparts, except that their large range in H, equivalent width indicates recent truncation of star formation. The red star-forming galaxies fall into two broad categories, one of them being massive galaxies in cluster cores dominated by an old stellar population, but with evidence of current star formation in the core (possibly linked with active galactic nuclei). For the remaining red star-forming galaxies, it is evident from spectral indices, stellar and gas-phase metallicities and mean stellar ages that their colours result from the predominance of a metal-rich stellar population. Only half of the red star-forming galaxies have extinction values consistent with a significant presence of dust. The implication of the properties of these star-forming galaxies on environmental studies, like that of the Butcher,Oemler effect, is discussed. [source] Standardized T2* map of normal human heart in vivo to correct T2* segmental artefactsNMR IN BIOMEDICINE, Issue 6 2007Vincenzo Positano Abstract A segmental, multislice, multi-echo T2* MRI approach could be useful in heart iron-overloaded patients to account for heterogeneous iron distribution, demonstrated by histological studies. However, segmental T2* assessment in heart can be affected by the presence of geometrical and susceptibility artefacts, which can act on different segments in different ways. The aim of this study was to assess T2* value distribution in the left ventricle and to develop a correction procedure to compensate for artefactual variations in segmental analysis. MRI was performed in four groups of 22 subjects each: healthy subjects (I), controls (II) (thalassemia intermedia patients without iron overload), thalassemia major patients with mild (III) and heavy (IV) iron overload. Three short-axis views (basal, median, and apical) of the left ventricle were obtained and analyzed using custom-written, previously validated software. The myocardium was automatically segmented into a 16-segment standardized heart model, and the mean T2* value for each segment was calculated. Punctual distribution of T2* over the myocardium was assessed, and T2* inhomogeneity maps for the three slices were obtained. In group I, no significant variation in the mean T2* among slices was found. T2* showed a characteristic circumferential variation in all three slices. The effect of susceptibility differences induced by cardiac veins was evident, together with low-scale variations induced by geometrical artefacts. Using the mean segmental deviations as correction factors, an artefact correction map was developed and used to normalize segmental data. The correction procedure was validated on group II. Group IV showed no significant presence of segmental artefacts, confirming the hypothesis that susceptibility artefacts are additive in nature and become negligible for high levels of iron overload. Group III showed a greater variability with respect to normal subjects. The correction map failed to compensate for these variations if both additive and percentage-based corrections were applied. This may reinforce the hypothesis that true inhomogeneity in iron deposition exists. Copyright © 2007 John Wiley & Sons, Ltd. [source] Middle East set to benefit as petrochemical demand growsOIL AND ENERGY TRENDS, Issue 8 2005Article first published online: 15 AUG 200 Strong worldwide demand for petrochemicals, particularly in China, is prompting many oil and petrochemical producers to build new ethylene capacity. China itself has extensive plans for capacity additions, as do some other Asian countries, but the largest increase looks set to come from the Middle East. Here, the growth will be based on access to abundant low-cost feedstocks, especially gas, which will give the region a considerable advantage over regions dependent on expensive oil-based feedstocks, including much of Asia. The exploitation of gas-based feedstocks has enabled the Middle East to build up a significant presence in world ethylene markets already. Since 2000, it has been the largest exporter of ethylene and its dominance could grow considerably over the coming decade, largely at the expense of the US. On present projections of demand and capacity, the Middle East is likely to account for well over 90% of the world's net trade in ethylene by 2010, with China as its principal market. [source] Mineral Paragenesis of the Lepanto Copper and Gold and the Victoria Gold Deposits, Mankayan Mineral District, PhilippinesRESOURCE GEOLOGY, Issue 2 2001Rene Juna R. CLAVERIA Abstract: Mineral paragenesis of the alteration, ore and gangue minerals of the Lepanto epithermal copper-gold deposit and the Victoria gold deposit, Mankayan Mineral District, Northern Luzon, Philippines, is discussed. The principal ore minerals of the Lepanto copper-gold deposit are enargite and luzonite, with significant presence of tennantite-tetrahedrite, chalcopyrite, sphalerite, galena, native gold/electrum and gold-silver tellurides. Pervasive alteration zonations are commonly observed from silicification outward to advanced argillic then to propylitic zone. The ore mineralogy of the Lepanto copper-gold deposit suggests high fS2 in the early stages of mineralization corresponding to the deposition of the enargite-luzonite-pyrite assemblage. Subsequent decrease in the fS2 formed the chalcopyrite-tennantite-pyrite assemblage. An increase in the fS2 of the fluids with the formation of the covellite-digenite-telluride assemblage caused the deposition of native gold/electrum and gold-silver tellurides. The principal ore minerals of the Victoria gold deposit are sphalerite, galena, chalcopyrite, tetrahedrite and native gold/electrum. The alteration halos are relatively narrow and in an outward sequence from the ore, silica alteration grades to illitic-argillic alteration, which in turn grades to propylitic alteration. The Victoria gold mineralization has undergone early stages of silica supersaturation leading to quartz deposition. Vigorous boiling increased the pH of the fluids that led to the deposition of sulfides and carbonates. The consequent decrease in H2S precipitated the gold. Gypsum and anhydrite mainly occur as overprints that cut the carbonate-silica stages. The crosscutting and overprinting relationships of the Victoria quartz-gold-base metal veins on the Lepanto copper-gold veins manifest the late introduction of near neutral pH hydrothermal fluids. [source] Imprisonment and Penal Policy in IrelandTHE HOWARD JOURNAL OF CRIMINAL JUSTICE, Issue 3 2004Ian O'Donnell Most notably, the average daily prison population grew swiftly at a time when recorded crime was falling. This contradictory trend was due to a combination of factors including the politicisation of the debate about crime, a build up of long-sentence prisoners, an expansion of the remand population and a reduction in the use of early release to ease overcrowding. The costs of incarceration, especially prison officer overtime, became the focus of acute concern and for the first time foreign nationals became a significant presence in Irish prisons. [source] Child Labour: a survey of selected Asian countriesASIAN-PACIFIC ECONOMIC LITERATURE, Issue 2 2004Ranjan Ray While the African continent has the highest child labour force participation rates, Asia contains the largest pool of child workers. The nature, magnitude and decline in child labour vary sharply between Asian countries. East Asia now has little child labour; however, child labour continues to have a significant presence in South Asia and in parts of Southeast Asia. This paper surveys the literature on child labour in selected Asian countries, paying special attention to its causes and consequences. The evidence presented shows that Asian child labour, especially in South and Southeast Asia, has some common features. For example, the bulk of child labour is in the 10,14 years age group. The phenomenon is largely rural, and child domestic labour constitutes a significant share. The participation rate of Asian children in the 15,17 years age group in economic activities, 48.4 per cent, is the highest in the world. There is a significant gender element in Asian child labour with boys outnumbering girls in economically active work, while the reverse is the case with domestic child labour. A focus of the survey is the empirical findings that provide insights into the policy instruments that may be needed in combating this phenomenon. The survey also discusses some of the important international and national initiatives that have been taken to reduce child labour. [source] Diffusion and NOE NMR Studies on Multicationic DAB-Organoruthenium Dendrimers: Size-Dependent Noncovalent Self-Assembly to Megamers and Ion Pairing,CHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2009Stefania Pettirossi Dr. Abstract Supra-mega ion pairing: Multicationic organoruthenium dendrimers show a notable tendency to self-aggregate when the concentration is increased, leading to megamers. This tendency increases with the generation. The self-aggregation of dendrimers to megamers is coupled with a decrease in the extent of ion pairing, as illustrated. New multicationic organoruthenium dendrimers (RuPF6 -Dabn, n=2, 4, 8, 16) have been synthesized by coupling of [Ru(,6 - p -cymene)(,3 -dpk-OCH2CH2OH)]X (1PF6, dpk=2,2,-dipyridyl ketone, X=PF6) with 1,4-diaminobutane (DAB) and polypropylenimine dendrimer DAB- dendr -(NH2)n {n=4, 8, 16} mediated by 1,1,-carbonyldiimidazole (CDI). The intermediate in the synthesis, [Ru(,6 - p -cymene)(,3 -dpk-OCH2CH2OC(O)Im]X (2PF6, Im=imidazole, X=PF6) has been isolated and characterized by single-crystal XRD. The intra- and supramolecular structures in a solution of RuPF6 -Dabn dendrimer have been investigated by multidimensional and multinuclear NMR techniques. Diffusion NMR experiments on dilute solutions indicated that the linear distance between two metal centers (14.9,22.1,Å depending on the dendrimer generation) is much greater than the diameter of 1PF6 (9.9,Å). 19F,1H-HOESY NMR experiments (HOESY= heteronuclear Overhauser effect spectroscopy) showed that the counterion is positioned on the surface of the dendrimers and assumes the same relative anion,cation orientation as in 2PF6. Diffusion NMR experiments on RuPF6 -Dabn dendrimers in CD2Cl2 at different concentrations revealed a process of supramolecular assembly of dendrimers to megamers that is strongly favored for the highest generations. Megamer formation is coupled with an increased fraction of free ions (,) and a consequent reduction in ion-paired ruthenium centers. Graphs of , versus CRu (the concentration of ruthenium centers) showed a minimum for RuPF6 -Dab4, RuPF6 -Dab8, and RuPF6 -Dab16 at a position coinciding with the significant presence of supramolecular dendritic dimers. The tendency to ion pairing decreases as the dendrimer generation increases. [source] | |||||||||||||