987 resultados para F3


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澜沧银铅锌矿床是滇西南发现的规模最大的多金属硫化物矿床,大地构造位置位于晚古生代大陆边缘裂谷系的澜沧裂谷北段,矿产资源储量达到大型,但因数十年来的开采,资源日趋枯竭.现今,在铅逐渐萎缩,锌稳步发展和银前景看好的市场趋势下,地表高品位炉碴和砂泥铅生产殆尽而转入深部开采.然而,矿山后备资源基地眉目不清,资源问题已成为严重制约矿山企业发展,甚至威胁企业生存的根本问题.同时,2万吨/年的"高压浸取电积锌"工艺即将投入工业生产,急待扩大生产规模.因此,当务之急是加强矿山深部和外围找矿,以期扩大后备资源储量.

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BACKGROUND: Fibronectin-null cells assemble soluble fibronectin shortly after adherence to a substrate coated with intact fibronectin but not when adherent to the cell-binding domain of fibronectin (modules (7)F3-(10)F3). Interactions of adherent cells with regions of adsorbed fibronectin other than modules (7)F3-(10)F3, therefore, are required for early display of the cell surface sites that initiate and direct fibronectin assembly. METHODOLOGY/PRINCIPAL FINDINGS: To identify these regions, coatings of proteolytically derived or recombinant pieces of fibronectin containing modules in addition to (7)F3-(10)F3 were tested for effects on fibronectin assembly by adherent fibronectin-null fibroblasts. Pieces as large as one comprising modules (2)F3-(14)F3, which include the heparin-binding and cell adhesion domains, were not effective in supporting fibronectin assembly. Addition of module (1)F3 or the C-terminal modules to modules (2)F3-(14)F3 resulted in some activity, and addition of both (1)F3 and the C-terminal modules resulted in a construct, (1)F3-C, that best mimicked the activity of a coating of intact fibronectin. Constructs (1)F3-C V0, (1)F3-C V64, and (1)F3-C Delta(V(15)F3(10)F1) were all able to support fibronectin assembly, suggesting that (1)F3 through (11)F1 and/or (12)F1 were important for activity. Coatings in which the active parts of (1)F3-C were present in different proteins were much less active than intact (1)F3-C. CONCLUSIONS: These results suggest that (1)F3 acts together with C-terminal modules to induce display of fibronectin assembly sites on adherent cells.

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1 kartta :, vär. ;, 50,6 x 43,1 cm, lehti 58 x 50,2 cm

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Tesis (Maestro en Ciencias de la Ingeniería en Manufactura con Especialidad en Automatización ) U.A.N.L.

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The binding of (-)[ 3H ]dihydroalprenolol , an antagonist of norepinephrine , to $-adrenergic receptors in different regions of the brain of male and female rats of various ages was measured . The binding to the synaptosomal fraction of corpus striatum , hypothalamus, cerebral cortex, cerebellum and the brainstems shows a significant decrease in the binding in old rats of both sexes . Only in the female corpus striatal region, the binding in the adult and the old is the same . In the case of females, the highest binding is seen in the young. In the male, an increase in binding occurs up to adulthood , after which it declines, suggesting a definite sex-related difference in the Q-adrenergic receptor.

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Resultaten av de senaste PIRLS-undersökningarna visar att svenska elevers läsförståelse har försämrats under senare år. Enligt forskning bör undervisningen vara inriktad på lässtrategier för att elever ska utveckla läsförståelse. För att eleverna ska lära sig använda olika lässtrategier självständigt när de tolkar text och skapar mening behöver de undervisas explicit. Undervisningen bör vara strukturerad och varierad samtidigt som läraren stöttar eleverna och anpassar undervisningen efter deras individuella behov. Syftet med studien har varit att undersöka hur lärare i F–3 undervisar i läsförståelse och lässtrategier för att se vilka förtjänster och brister som finns. Studiens metod är kvalitativ och för att samla in material har fem halvstrukturerade intervjuer genomförts med fem verksamma lärare, fyra klasslärare och en specialpedagog, fördelade på fyra olika skolor. Resultaten visar att lärare använder sig av olika undervisningsmetoder när de undervisar i läsförståelse, såsom en läsande klass, think-aloud, cirkelmodellen och Chambers modell för boksamtal. Det som tycks genomsyra lärarnas undervisning i läsförståelse är kommunikation, vilket är nära sammankopplat med studiens teoretiska utgångspunkt, det sociokulturella perspektivet. Enligt lärarna samtalar de mycket med eleverna om texter, och de verkar försöka anpassa undervisningen efter elevernas individuella behov genom att välja texter som eleverna har förkunskaper i och om. När de undervisar explicit tycks lärarna diskutera olika lässtrategiers nyttoanvändning genom att samtala om hur och varför olika lässtrategier är lämpliga att använda i olika sammanhang. Enligt lärarna erbjuds eleverna undervisning i olika gruppkonstellationer såsom arbete i helklass, halvklass, mindre grupper, parvis och enskilt. Lärarna tycks vara tydliga i sin undervisning för att eleverna ska bli medvetna om i vilket syfte de ska läsa.

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Introduction: The aim of this study was to assess the occurrence of apical root transportation after the use of Pro Taper Universal rotary files sizes 3 (F3) and 4 (F4). Methods: Instruments were worked to the apex of the original canal, always by the same operator. Digital subtraction radiography images were produced in buccolingual and mesiodistal projections. A total of 25 radiographs were taken from root canals of human maxillary first molars with curvatures varying from 23-31 degrees. Quantitative data were analyzed by intraclass correlation coefficient and Wilcoxon nonparametric test (P = .05). Results: Buccolingual images revealed a significantly higher degree of apical transportation associated with F4 instruments when compared with F3 instruments in relation to the original canal (Wilcoxon test, P = .007). No significant difference was observed in mesiodistal images (P = .492). Conclusions: F3 instruments should be used with care in curved canals, and F4 instruments should be avoided in apical third preparation of curved canals. (J Endod 2010;36:1052-1055)

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Aims: An extensive variety of prenatal insults are associated with an increased incidence of metabolic and cardiovascular disorders in adult life. We previously demonstrated that maternal global nutrient restriction during pregnancy leads to increased blood pressure and endothelial dysfunction in the adult offspring. This study aimed to assess whether prenatal exposure to nutritional insult has transgenerational effects in F-2 and F-3 offspring. Main methods: For this, female Wistar rats were randomly divided into two groups on day 1 of pregnancy: a control group fed standard chow ad libitum and a restricted group fed 50% of the ad libitum intake throughout gestation. At delivery, all animals were fed a standard laboratory chow diet. At 11 weeks of age, one female and one male from each restricted litter were randomly selected and mated with rats from another restricted litters in order to generate the F-2 offspring. The same procedure produced F-3 generation. Similarly, the rats in the control group were bred for each generation. Key Findings: Our findings show that the deleterious effects of maternal nutrient restriction to which the F-0 mothers were exposed may not be limited to the male first generation. In fact, we found that elevated blood pressure, an impaired vasodilatory response to acetylcholine and alterations in NO production were all transferred to the subsequent males from F-2 and F-3 generations. Significance: Our data show that global nutrient restriction during pregnancy results in a specific phenotype that can be passed transgenerationally to a second and third generation. (c) 2012 Elsevier Inc. All rights reserved.

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Background: Hepatitis B virus (HBV) infection is one of the most prevalent viral infections in humans and represents a serious public health problem. In Colombia, our group reported recently the presence of subgenotypes F3, A2 and genotype G in Bogota. The aim of this study was to characterize the HBV genotypes circulating in Quibdo, the largest Afro-descendant community in Colombia. Sixty HBsAg-positive samples were studied. A fragment of 1306 bp (S/POL) was amplified by nested PCR. Positive samples to S/POL fragment were submitted to PCR amplification of the HBV complete genome. Findings: The distribution of HBV genotypes was: A1 (52.17%), E (39.13%), D3 (4.3%) and F3/A1 (4.3%). An HBV recombinant strain subgenotype F3/A1 was found for the first time. Conclusions: This study is the first analysis of complete HBV genome sequences from Afro-Colombian population. It was found an important presence of HBV/A1 and HBV/E genotypes. A new recombinant strain of HBV genotype F3/A1 was reported in this population. This fact may be correlated with the introduction of these genotypes in the times of slavery.

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Reflection seismic data from the F3 block in the Dutch North Sea exhibits many large-amplitude reflections at shallow horizons, typically categorized as “brightspots ” (Schroot and Schuttenhelm, 2003), mainly because of their bright appearance. In most cases, these bright reflections show a significant “flatness” contrasting with local structural trends. While flatspots are often easily identified in thick reservoirs, we have often occasionally observed apparent flatspot tuning effects at fluid contacts near reservoir edges and in thin reservoir beds, while only poorly understanding them. We conclude that many of the shallow large-amplitude reflections in block F3 are dominated by flatspots, and we investigate the thin-bed tuning effects that such flatspots cause as they interact with the reflection from the reservoir’s upper boundary. There are two possible effects to be considered: (1) the “wedge-model” tuning effects of the flatspot and overlying brightspots, dimspots, or polarity-reversals; and (2) the stacking effects that result from possible inclusion of post-critical flatspot reflections in these shallow sands. We modeled the effects of these two phenomena for the particular stratigraphic sequence in block F3. Our results suggest that stacking of post-critical flatspot reflections can cause similar large-amplitude but flat reflections, in some cases even causing an interface expected to produce a ‘dimspot’ to appear as a ‘brightspot’. Analysis of NMO stretch and muting shows the likely exclusion of critical offset data in stacked output. If post-critical reflections are included in stacking, unusual results will be observed. In the North Sea case, we conclude the tuning effect was the primary reason causing for the brightness and flatness of these reflections. However, it is still important to note that care should be taken while applying muting on reflections with wide range of incidence angles and the inclusion of critical offset data may cause some spurious features in the stacked section.