982 resultados para 428
Resumo:
The effects of competing magneto-crystalline and shape anisotropies on magnetization reversal were studied in situ in arrays of sub-micron Fe/Co ellipses of compositions Fe2/Co6 and Fe8/Co3 with magnetic force microscopy (MFM). A simple model assigning magnetization values to the different types of domain structures observed in the MFM images was used to estimate the field dependence of the total magnetization of a sample. The agreement with macroscopic magnetization measurements is discussed.
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Duckweeds are a common macrophyte in paddy and aquatic environments. Here, we investigated arsenic (As) accumulation, speciation and tolerance of the rootless duckweed Wolffia globosa and its potential for As phytofiltration.
When grown with 1 mu M arsenate, W. globosa accumulated two to 10 times more As than four other duckweed or Azolla species tested. W. globosa was able to accumulate > 1000 mg As kg(-1) in frond dry weight (DW), and tolerate up to 400 mg As kg-1 DW. At the low concentration range, uptake rate was similar for arsenate and arsenite, but at the high concentration range, arsenite was taken up at a faster rate.
Arsenite was the predominant As species (c. 90% of the total extractable As) in both arsenate-and arsenite-exposed duckweed. W. globosa was more resistant to external arsenate than arsenite, but showed a similar degree of tolerance internally. W. globosa decreased arsenate in solution rapidly, but also effluxed arsenite.
Wolffia globosa is a strong As accumulator and an interesting model plant to study As uptake and metabolism because of the lack of a root-to-frond translocation
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A downstream target of the Wnt pathway, neurone glial-related cell adhesion molecule (Nr-CAM) has recently been implicated in human cancer development. However, its role in colorectal cancer (CRC) pathobiology and clinical relevance remains unknown. In this study, we examined the clinical significance of Nr-CAM protein expression in a retrospective series of 428 CRCs using immunohistochemistry and tissue microarrays. Cox proportional hazards regression was used to calculate hazard ratios (HR) of mortality according to various clinicopathological features and molecular markers. All CRC samples were immunoreactive for Nr-CAM protein expression, compared to 10 / 245 (4%) matched normal tissue (P <0.0001). Of 428 CRC samples, 97 (23%) showed Nr-CAM overexpression, which was significantly associated with nodal (P = 0.012) and distant (P = 0.039) metastasis, but not with extent of local invasion or tumor size. Additionally, Nr-CAM overexpression was associated with vascular invasion (P = 0.0029), p53 expression (P = 0.036), and peritoneal metastasis at diagnosis (P = 0.013). In a multivariate model adjusted for other clinicopathological predictors of survival, Nr-CAM overexpression correlated with a significant increase in disease-specific (HR 1.66; 95% confidence interval 1.11-2.47; P = 0.014) and overall mortality (HR 1.57; 95% confidence interval 1.07-2.30; P = 0.023) in advanced but not early stage disease. Notably, 5-fluorouracil-based chemotherapy conferred significant survival benefit to patients with tumors negative for Nr-CAM overexpression but not to those with Nr-CAM overexpressed tumors. In conclusion, Nr-CAM protein expression is upregulated in CRC tissues. Nr-CAM overexpression is an independent marker of poor prognosis among advanced CRC patients, and is a possible predictive marker for non-beneficence to 5-fluorouracil- based chemotherapy.
Resumo:
The neuregulin-1 gene (NRG1) at chromosome 8p21-22 has been implicated as a schizophrenia susceptibility gene in Icelandic, Scottish, Irish and mixed UK populations. The shared ancestry between these populations led us to investigate the NRG1 polymorphisms and appropriate marker haplotypes for linkage and/or association to schizophrenia in the Irish study of high-density schizophrenia families (ISHDSF). Neither single-point nor multi-point linkage analysis of NRG1 markers gave evidence for linkage independent of our pre-existing findings telomeric on 8p. Analysis of linkage disequilibrium (LD) across the 252 kb interval encompassing the 7 marker core Icelandic/Scottish NRG1 haplotype revealed two separate regions of modest LD, comprising markers SNP8NRG255133, SNP8NRG249130 and SNP8NRG243177 (telomeric) and microsatellites 478B14-428, 420M9-1395, D8S1810 and 420M9-116I12 (centromeric). From single marker analysis by TRANSMIT and FBAT we found no evidence for association with schizophrenia for any marker. Haplotype analysis for the three SNPs in LD region 1 and, separately, the four microsatellites in LD region 2 (analyzed in overlapping 2-marker windows), showed no evidence for overtransmission of specific haplotypes to affected individuals. We therefore conclude that if NRG1 does contain susceptibility alleles for schizophrenia, they impact quite weakly on risk in the ISHDSF.
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Sponge classification has long been based mainly on morphocladistic analyses but is now being greatly challenged by more than 12 years of accumulated analyses of molecular data analyses. The current study used phylogenetic hypotheses based on sequence data from 18S rRNA, 28S rRNA, and the CO1 barcoding fragment, combined with morphology to justify the resurrection of the order Axinellida Lévi, 1953. Axinellida occupies a key position in different morphologically derived topologies. The abandonment of Axinellida and the establishment of Halichondrida Vosmaer, 1887 sensu lato to contain Halichondriidae Gray, 1867, Axinellidae Carter, 1875, Bubaridae Topsent, 1894, Heteroxyidae Dendy, 1905, and a new family Dictyonellidae van Soest et al., 1990 was based on the conclusion that an axially condensed skeleton evolved independently in separate lineages in preference to the less parsimonious assumption that asters (star-shaped spicules), acanthostyles (club-shaped spicules with spines), and sigmata (C-shaped spicules) each evolved more than once. Our new molecular trees are congruent and contrast with the earlier, morphologically based, trees. The results show that axially condensed skeletons, asters, acanthostyles, and sigmata are all homoplasious characters. The unrecognized homoplasious nature of these characters explains much of the incongruence between molecular-based and morphology-based phylogenies. We use the molecular trees presented here as a basis for re-interpreting the morphological characters within Heteroscleromorpha. The implications for the classification of Heteroscleromorpha are discussed and a new order Biemnida ord. nov. is erected.
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The work aims at assessing the success of Brunetta’s reform (Legislative Decree n. 150/2009), a far-reaching reform that aimed at improving both organizational and individual performance in Italian public administration through a specific planning and control process (the performance cycle) and most of all through two new tools, Performance Plan and Performance Report. The success of the reform is assessed, with particular emphasis on local governments, analyzing the diffusion and use of these new tools. The study has been conducted using a deductive-inductive methodology. Thus, after a study of managerial reforms in Italy and performance measurement literature, a possible model (PerformEL Model) local governments could follow to draw up Performance Plan and Report as effective tools for performance measurement has been designed (deductive phase). Performance Plans 2011-2013 and Performance Report 2011 downloaded from Italian big sized municipalities’ websites have been analyzed in the light of PerformEL Model, to assess the diffusion of the documents and their coherence with legal requirements and suggestions from literature (inductive phase). Data arising from the empirical analysis have been studied to evaluate the diffusion and the effectiveness of big sized municipalities’ Performance Plans and Reports as performance measurement tools and thus to assess the success of the reform (feedback phase). The study shows a scarce diffusion of the documents; they are mostly drew up because of their compulsoriness or to gain legitimization. The results testify the failure of Brunetta’s reform, at least with regard to local governments.
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High-cadence, multiwavelength observations and simulations are employed for the analysis of solar photospheric magnetic bright points (MBPs) in the quiet Sun. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere (ROSA) imager and the Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope. Our analysis reveals that photospheric MBPs have an average transverse velocity of approximately 1 km s-1, whereas their chromospheric counterparts have a slightly higher average velocity of 1.4 km s-1. Additionally, chromospheric MBPs were found to be around 63 per cent larger than the equivalent photospheric MBPs. These velocity values were compared with the output of numerical simulations generated using the muram code. The simulated results were similar, but slightly elevated, when compared to the observed data. An average velocity of 1.3 km s-1 was found in the simulated G-band images and an average of 1.8 km s-1 seen in the velocity domain at a height of 500 km above the continuum formation layer. Delays in the change of velocities were also analysed. Average delays of ˜4 s between layers of the simulated data set were established and values of ˜29 s observed between G-band and Ca ii K ROSA observations. The delays in the simulations are likely to be the result of oblique granular shock waves, whereas those found in the observations are possibly the result of a semi-rigid flux tube.
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In a large scale survey of rice grains from markets (13 countries) and fields (6 countries), a total of 1578 rice grain samples were analysed for lead. From the market collected samples, only 0.6% of the samples exceeded the Chinese and EU limit of 0.2 μg g− 1 lead in rice (when excluding samples collected from known contaminated/mine impacted regions). When evaluating the rice grain samples against the Food and Drug Administration's (FDA) provisional total tolerable intake (PTTI) values for children and pregnant women, it was found that only people consuming large quantities of rice were at risk of exceeding the PTTI from rice alone. Furthermore, 6 field experiments were conducted to evaluate the proportion of the variation in lead concentration in rice grains due to genetics. A total of 4 of the 6 field experiments had significant differences between genotypes, but when the genotypes common across all six field sites were assessed, only 4% of the variation was explained by genotype, with 9.5% and 11% of the variation explained by the environment and genotype by environment interaction respectively. Further work is needed to identify the sources of lead contamination in rice, with detailed information obtained on the locations and environments where the rice is sampled, so that specific risk assessments can be performed.
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DC line faults on high-voltage direct current (HVDC) systems utilising voltage source converters (VSCs) are a major issue for multi-terminal HVDC systems in which complete isolation of the faulted system is not a viable option. Of these faults, single line-to-earth faults are the most common fault scenario. To better understand the system under such faults, this study analyses the behaviour of HVDC systems based on both conventional two-level converter and multilevel modular converter technology, experiencing a permanent line-to-earth fault. Operation of the proposed system under two different earthing configurations of converter side AC transformer earthed with converter unearthed, and both converter and AC transformer unearthed, was analysed and simulated, with particular attention paid to the converter operation. It was observed that the development of potential earth loops within the system as a result of DC line-to-earth faults leads to substantial overcurrent and results in oscillations depending on the earthing configuration.
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The oncogenic role of WNT is well characterized. Wntless (WLS) (also known as GPR177, or Evi), a key modulator of WNT protein secretion, was recently found to be highly overexpressed in malignant astrocytomas. We hypothesized that this molecule may be aberrantly expressed in other cancers known to possess aberrant WNT signaling such as ovarian, gastric, and breast cancers. Immunohistochemical analysis using a TMA platform revealed WLS overexpression in a subset of ovarian, gastric, and breast tumors; this overexpression was associated with poorer clinical outcomes in gastric cancer (P=0.025). In addition, a strong correlation was observed between WLS expression and human epidermal growth factor receptor 2 (HER2) overexpression. Indeed, 100% of HER2-positive intestinal gastric carcinomas, 100% of HER2-positive serous ovarian carcinomas, and 64% of HER2-positive breast carcinomas coexpressed WLS protein. Although HER2 protein expression or gene amplification is an established predictive biomarker for trastuzumab response in breast and gastric cancers, a significant proportion of HER2-positive tumors display resistance to trastuzumab, which may be in part explainable by a possible mechanistic link between WLS and HER2.
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This paper will discuss the issues of spatial segregation in the divided city context,focusing on Belfast as a case study it will discuss, issues that limit the inclusivity of shared space in the city, the challenge of insular spatial patterns created by division, and the micro politics of everyday contact. It will argue the significance of creating everyday space to enable practical socio-spatial interaction between divided groups and propose that areas on community borders can be developed as active spaces accommodating services that the communities need, use, and want on an everyday basis, by doing so it offers a potential form valuable contact. It will report on an ongoing study which examines such sites located on community border and assesses their capacity to act as beneficial ‘spaces of engagement’ for communities set within divided context.
Resumo:
The peroxometalate-based polymer immobilized ionic liquid phase catalyst [PO4{WO(O-2)(2)}(4)]@PIILP has been prepared by anion exchange of ring opening metathesis-derived pyrrolidinium-decorated norbornene/ cyclooctene copolymer and shown to be a remarkably efficient system for the selective oxidation of sulfides under mild conditions. A cartridge packed with a mixture of [PO4{WO(O-2)(2)}(4)]@PIILP and silica operated as a segmented or continuous flow process and gave good conversions and high selectivity for either sulfoxide (92% in methanol at 96% conversion for a residence time of 4 min) or sulfone (96% in acetonitrile at 96% conversion for a residence time of 15 min). The immobilized catalyst remained active for 8 h under continuous flow operation with a stable activity/selectivity profile that allowed 6.5 g of reactant to be processed (TON = 46 428) while a single catalyst cartridge could be used for the consecutive oxidation of multiple substrates giving activity-selectivity profiles that matched those obtained with fresh catalyst.
Resumo:
ADAM17 (where ADAM is 'a disintegrin and metalloproteinase') can rapidly modulate cell-surface signalling events by the proteolytic release of soluble forms of proligands for cellular receptors. Many regulatory pathways affect the ADAM17 sheddase activity, but the mechanisms for the activation are still not clear. We have utilized a cell-based ADAM17 assay to show that thiol isomerases, specifically PDI (protein disulfide isomerase), could be responsible for maintaining ADAM17 in an inactive form. Down-regulation of thiol isomerases, by changes in the redox environment (for instance as elicited by phorbol ester modulation of mitochondrial reactive oxygen species) markedly enhanced ADAM17 activation. On the basis of ELISA binding studies with novel fragment antibodies against ADAM17 we propose that isomerization of the disulfide bonds in ADAM17, and the subsequent conformational changes, form the basis for the modulation of ADAM17 activity. The shuffling of disulfide bond patterns in ADAMs has been suggested by a number of recent adamalysin crystal structures, with distinct disulfide bond patterns altering the relative orientations of the domains. Such a mechanism is rapid and reversible, and the role of thiol isomerases should be investigated further as a potential factor in the redox regulation of ADAM17.