990 resultados para Seeded region growing


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During activation, T lymphocytes become motile cells, switching from a spherical to a polarized shape. Chemokines and other chemotactic cytokines induce lymphocyte polarization with the formation of a uropod in the rear pole, where the adhesion receptors intercellular adhesion molecule-1 (ICAM-1), ICAM-3, and CD44 redistribute. We have investigated membrane-cytoskeleton interactions that play a key role in the redistribution of adhesion receptors to the uropod. Immunofluorescence analysis showed that the ERM proteins radixin and moesin localized to the uropod of human T lymphoblasts treated with the chemokine RANTES (regulated on activation, normal T cell expressed, and secreted), a polarization-inducing agent; radixin colocalized with arrays of myosin II at the neck of the uropods, whereas moesin decorated the most distal part of the uropod and colocalized with ICAM-1, ICAM-3, and CD44 molecules. Two other cytoskeletal proteins, ß-actin and ¿-tubulin, clustered at the cell leading edge and uropod, respectively, of polarized lymphocytes. Biochemical analysis showed that moesin coimmunoprecipitates with ICAM-3 in T lymphoblasts stimulated with either RANTES or the polarization- inducing anti-ICAM-3 HP2/19 mAb, as well as in the constitutively polarized T cell line HSB-2. In addition, moesin is associated with CD44, but not with ICAM-1, in polarized T lymphocytes. A correlation between the degree of moesin-ICAM-3 interaction and cell polarization was found as determined by immunofluorescence and immunoprecipitation analysis done in parallel. The moesin-ICAM-3 interaction was specifically mediated by the cytoplasmic domain of ICAM-3 as revealed by precipitation of moesin with a GST fusion protein containing the ICAM-3 cytoplasmic tail from metabolically labeled Jurkat T cell lysates. The interaction of moesin with ICAM-3 was greatly diminished when RANTES-stimulated T lymphoblasts were pretreated with the myosin-disrupting drug butanedione monoxime, which prevents lymphocyte polarization. Altogether, these data indicate that moesin interacts with ICAM-3 and CD44 adhesion molecules in uropods of polarized T cells; these data also suggest that these interactions participate in the formation of links between membrane receptors and the cytoskeleton, thereby regulating morphological changes during cell locomotion.

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Report on a special investigation of the Region 4 Fusion Office in Atlantic, Iowa for the period March 1, 2006 through August 31, 2009

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Ultramafic rocks, mainly serpentinized peridotites of mantle origin, are mostly associated with the ophiolites of Mesozoic age that occur in belts along three of the margins of the Caribbean plate. The most extensive exposures are in Cuba. The ultramafic-mafic association (ophiolites) were formed and emplaced in several different tectonic environments. Mineralogical studies of the ultramafic rocks and the chemistry of the associated mafic rocks indicate that most of the ultramafic-mafic associations in both the northern and southern margins of the plate were formed in arc-related environments. There is little mantle peridotite exposed in the ophiolitic associations of the west coast of Central America, in the south Caribbean in Curacao and in the Andean belts in Colombia. In these occurrences the chemistry and age of the mafic rocks indicates that this association is mainly part of the 89 Ma Caribbean plateau province. The age of the mantle peridotites and associated ophiolites is probably mainly late Jurassic or Early Cretaceous. Emplacement of the ophiolites possibly began in the Early Cretaceous in Hispaniola and Puerto Rico, but most emplacement took place in the Late Cretaceous to Eocene (e.g. Cuba). Along the northern South America plate margin, in the Caribbean mountain belt, emplacement was by major thrusting and probably was not completed until the Oligocene or even the early Miocene. Caribbean mantle peridotites, before serpentinization, were mainly harzburgites, but dunites and lherzolites are also present. In detail, the mineralogical and chemical composition varies even within one ultramafic body, reflecting melting processes and peridotite/melt interaction in the upper mantle. At least for the northern Caribbean, uplift (postemplacement tectonics) exposed the ultramafic massifs as a land surface to effective laterization in the beginning of the Miocene. Tectonic factors, determining the uplift, exposing the peridotites to weathering varied. In the northern Caribbean, in Guatemala, Jamaica, and Hispaniola, uplift occurred as a result of transpresional movement along pre-existing major faults. In Cuba, uplift occurred on a regional scale, determined by isostatic adjustment. In the south Caribbean, uplift of the Cordillera de la Costa and Serrania del Interior exposing the peridotites, also appears to be related to strike-slip movement along the El Pilar fault system. In the Caribbean, Ni-laterite deposits are currently being mined in the central Dominican Republic, eastern Cuba, northern Venezuela and northwest Colombia. Although apparently formed over ultramafic rocks of similar composition and under similar climatic conditions, the composition of the lateritic soils varies. Factors that probably determined these differences in laterite composition are geomorphology, topography, drainage and tectonics. According to the mineralogy of principal ore-bearing phases, Dominican Ni-laterite deposits are classified as the hydrous silicate-type. The main Ni-bearing minerals are hydrated Mg-Ni silicates (serpentine and ¿garnierite¿) occurring deeper in the profile (saprolite horizon). In contrast, in the deposits of eastern Cuba, the Ni and Cooccurs mainly in the limonite zone composed of Fe hydroxides and oxides as the dominant mineralogy in the upper part of the profile, and are classified as the oxide-type.

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The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis) to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation. C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun.

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A large proportion of soybean fields in Brazil are currently cultivated in the Cerrado region, where the area planted with this crop is growing considerably every year. Soybean cultivation in acid soils is also increasing worldwide. Since the levels of toxic aluminum (Al) in these acid soils is usually high it is important to understand how cations can reduce Al rhizotoxicity in soybean. In the present study we evaluated the ameliorative effect of nine divalent cations (Ca, Mg, Mn, Sr, Sn, Cu, Zn, Co and Ba) in solution culture on Al rhizotoxicity in soybean. The growth benefit of Ca and Mg to plants in an acid Inceptisol was also evaluated. In this experiment soil exchangeable Ca:Mg ratios were adjusted to reach 10 and 60 % base saturation, controlled by different amounts of CaCl2 or MgCl2 (at proportions from 100:0 up to 0:100), without altering the soil pH level. The low (10 %) and adequate (60 %) base saturation were used to examine how plant roots respond to Al at distinct (Ca + Mg)/Al ratios, as if they were growing in soils with distinct acidity levels. Negative and positive control treatments consisted of absence (under native soil or undisturbed conditions) or presence of lime (CaCO3) to reach 10 and 60 % base saturation, respectively. It was observed that in the absence of Aluminum, Cu, Zn, Co and Sn were toxic even at a low concentration (25 µmol L-1), while the effect of Mn, Ba, Sr and Mg was positive or absent on soybean root elongation when used in concentrations up to 100 µmol L-1. At a level of 10 µmol L-1 Al, root growth was only reverted to the level of control plants by the Mg treatment. Higher Tin doses led to a small alleviation of Al rhizotoxicity, while the other cations reduced root growth or had no effect. This is an indication that the Mg effect is ion-specific and not associated to an electrostatic protection mechanism only, since all ions were divalent and used at low concentrations. An increased exchangeable Ca:Mg ratio (at constant soil pH) in the acid soil almost doubled the soybean shoot and root dry matter even though treatments did not modify soil pH and exchangeable Al3+. This indicates a more efficient alleviation of Al toxicity by Mg2+ than by Ca2+. The reason for the positive response to Mg2+ was not the supply of a deficient nutrient because CaCO3 increased soybean growth by increasing soil pH without inducing Mg2+ deficiency. Both in hydroponics and acid soil, the reduction in Al toxicity was accompanied by a lower Al accumulation in plant tissue, suggesting a competitive cation absorption and/or exclusion of Al from plant tissue stimulated by an Mg-induced physiological mechanism.

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Selostus: Lajikkeen, typpilannoitustason ja maalajin vaikutus ohran ruokinnalliseen arvoon lihasioilla

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The wing of the fruit fly, Drosophila melanogaster, with its simple, two-dimensional structure, is a model organ well suited for a systems biology approach. The wing arises from an epithelial sac referred to as the wing imaginal disc, which undergoes a phase of massive growth and concomitant patterning during larval stages. The Decapentaplegic (Dpp) morphogen plays a central role in wing formation with its ability to co-coordinately regulate patterning and growth. Here, we asked whether the Dpp signaling activity scales, i.e. expands proportionally, with the growing wing imaginal disc. Using new methods for spatial and temporal quantification of Dpp activity and its scaling properties, we found that the Dpp response scales with the size of the growing tissue. Notably, scaling is not perfect at all positions in the field and the scaling of target gene domains is ensured specifically where they define vein positions. We also found that the target gene domains are not defined at constant concentration thresholds of the downstream Dpp activity gradients P-Mad and Brinker. Most interestingly, Pentagone, an important secreted feedback regulator of the pathway, plays a central role in scaling and acts as an expander of the Dpp gradient during disc growth.

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This work is focused on the study of the fine speckle contrast present in planar view observations of matched and mismatched InGaAs layers grown by molecular beam epitaxy on InP substrates. Our results provide experimental evidence of the evolution of this fine structure with the mismatch, layer thickness, and growth temperature. The correlation of the influence of all these parameters on the appearance of the contrast modulation points to the development of the fine structure during the growth. Moreover, as growth proceeds, this structure shows a dynamic behavior which depends on the intrinsic layer substrate stress.

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Selostus: Eri absorbenteilla valmistettu säilörehu karitsoiden ruokinnassa

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Background: Population-based cohort studies of risk factors of stroke are scarce in developing countries and none has been done in the African region. We conducted a longitudinal study in the Seychelles (Indian Ocean, east of Kenya), a middle-income island state where the majority of the population is of African descent. Such data in Africa are important for international comparison and for advocacy in the region. Methods: Three examination surveys of cardiovascular risk factors were performed in independent samples representative of the general population aged 25-64 in 1989, 1994 and 2004 (n=1081, 1067, and 1255, respectively). Baseline risk factors data were linked with cause-specific mortality from vital statistics up to May 2007 (all deaths are medically certified in the Seychelles and kept in an electronic database). We considered stroke (any type) as a cause of death if the diagnosis was reported in any of the 4 fields in the death certificates for underlying and concomitant causes of death. Results. Among the 2479 persons aged 35-64 at baseline, 280 died including 56 with stroke during follow up (maximum: 18.2 years; mean: 10.2 years). In this age range, age-adjusted mortality rates (/100'000/year) were 969 for all cause and 187 for stroke; age-adjusted prevalence of high blood pressure (≥140/90 mmHg) was 48%. In multivariate Cox survival time regression, stroke mortality was increased by 18% and 35% for a 10-mmHg increase in systolic, respectively diastolic BP (p<0.001). Stroke mortality was also associated with age, smoking ≥5 cigarettes vs. no smoking (HR: 2.4; 95% CI: 1.2-4.8) and diabetes (HR: 1.9; 1.02-3.6) but not with sex, LDL-cholesterol intake, alcohol intake and professional occupation. Conclusion. This first population-based cohort study in the African region demonstrates high mortality rates from stroke in middle-aged adults and confirms associations with high BP and other risk factors. This emphasizes the importance of reducing BP and other modifiable risk factors in high risk individuals and in the general population as a main strategy to reduce the burden of stroke.

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BACKGROUND: Few European studies have investigated how cardiovascular risk factors (CRF) in adults relate to those observed in younger generations. OBJECTIVE: To explore this issue in a Swiss region using two population health surveys of 3636 adolescents ages 9-19 years and 3299 adults ages 25-74 years. METHODS: Age patterns of continuous CRF were estimated by robust locally weighted regression and those of high-risk groups were calculated using adult criteria with appropriate adjustment for children. RESULTS: Gender differences in height, weight, blood pressure, and HDL cholesterol observed in adults were found to emerge in adolescents. Overweight, affecting 10-12% of adolescents, was increasing steeply in young adults (three times among males and twice among females) in parallel with inactivity. Median age at smoking initiation was decreasing rapidly from 18 to 20 years in young adults to 15 in adolescents. A statistically significant social gradient in disfavor of the lower education level was observed for overweight in all age groups of women above 16 (odds ratios (ORs) 2.4 to 3.3, P < 0.01), for inactivity in adult males (ORs 1.6 to 2.0, P < 0.05), and for regular smoking in older adolescents (OR 1.9 for males, 2.7 for females, P < 0.005), but not for elevated blood pressure. CONCLUSION: Discontinuities in the cross-sectional age patterns of CRF indicated the emergence of a social gradient and the need for preventive actions against the early adoption of persistent unhealthy behaviors, to which low-educated girls and women are particularly exposed.

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Selostus: Rehun valkuais- ja energiapitoisuuden vaikutus sikojen typen hyväksikäyttöön, veden kulutukseen ja virtsan eritykseen

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[cat] En aquest treball presentem un model per explicar el procés d’especialització vitícola assolit als municipis de la província de Barcelona, a mitjans del s. XIX,que cerca entendre com va sorgir històricament un avantatge comparatiu fruit d’un procés que esdevindria un dels punts de partida del procés d’industrialització a Catalunya. Els resultats confirmen els papers jugats pel impuls “Boserupià” de la població en un context d’intensificació de l’ús de la terra, i d’un impuls del mercat “Smithià” en un context d’expansió de la demanda per part de les economies atlàntiques. També es posa de manifest la importància de les dotacions agro-ecològiques i les condicions socioinstitucionals relacionades amb la desigualtat d’ingrés. La difusió de la vinya donà com a resultat unes comunitats rurals menys desiguals fins al 1820, tot i que aquesta desigualtat augmentà de nou a partir d'aleshores.