733 research outputs found

    A Visual Typology of Abandonment in Rural America: From End-of-Life to Treading Water, Recycling, Renaissance, and Revival

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    The contemporary American rural landscape reflects a mix of ongoing economic changes in agricultural land use, population change, and built environments. The mix depends on past and recent change which represent landscapes of memory and silence to those experiencing economic and demographic renaissance. We develop a typology of five stages that reflect the contemporary rural scene and conduct field transects in Northwest Iowa and Central Maine. Features of the dynamics in rural America are evident in photographs of residences, land use changes, and commercial structure. The study calls for additional studies on rural settlement populations, economies, and society in different environmental settings

    Volumetrie der Schilddrüsenlappen mittels Real-time-Sonographie

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    Im direkten Vergleich mit der durch Submersion ermittelten wahren Schilddrüsengröße wurde bei Leichen mit einem Real-time-Gerät ein Verfahren zur Volumenbestimmung durch sonographische Messungen erarbeitet. Länge mal Breite mal Dicke des Schilddrüsenlappens, multipliziert mit dem Faktor π/6, entsprechen einem Rotationsellipsoid, während sich bei Multiplikation mit dem optimierten Korrekturfaktor f = 0,479 das bestmögliche rechnerische Volumen des Lappens ergibt. Die Richtigkeit dieser Bestimmung ist definitionsgemäß 100 %; der. durchschnittliche Fehler der Methode beträgt 16 %. Die Messungen sind einfach durchzuführen und verlangen keinerlei Zusatzeinrichtungen für Planimetrie oder Rechneroperationen. Die Volumetrie der Schilddrüse ist vor allem zur Therapiebeurteilung und zur Berechnung der Dosis bei einer Radiojodtherapie erforderlich.Thyroid volume as measured by real-time ultrasound in cadavers was compared with direct measurements obtained by submersion. Length × width × thickness of the thyroid lobe multiplied by factor π/6, correspond to a rotation ellipsoid, while the best calculated volume of the lobe is obtained by multiplying with the optimised correction factor f = 0.479. The correctness of this calculation is, by definition, 100 %; average error of the method is 16 %. The measurements are easy to do and require no additional equipment for planimetry or calculations. Volumetric analysis of the thyroid gland is especially necessary in assessing results of treatment and for measuring dosage in connection with radioiodine therapy

    Light can rescue auxin-dependent synchrony of cell division in a tobacco cell line

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    Pattern formation in plants has to cope with ambient variability and therefore must integrate environmental cues such as light. Synchrony of cell divisions was previously observed in cell files of tobacco suspension cultures, which represents a simple case of pattern formation. To develop cellular approaches for light-dependent patterning, light-responsive tobacco cell lines were screened from the cell line Nicotiana tabacum L. cv. Virginia Bright Italia 0 (VBI-0). The light responsive and auxin-autonomous cell line VBI-3 was isolated. As in the progenitor line VBI-0, cell divisions are synchronized in VBI-3 during exponential growth phase. This synchrony can be inhibited by 1-N-naphthylphthalamic acid, an auxin transport inhibitor, and this process was accompanied by the disassembly of actin filaments. However, the synchrony could be rescued when the cells were cultured under white light or with exogenous indolyl-3-acetic acid. The rescue was most efficient for continuous far-red light followed by continuous blue light, whereas continuous red light was least effective. These findings are discussed in the context of phytochrome-induced auxin biosynthesis and auxin-dependent synchrony of cell division

    Estimating the global root exudate carbon flux

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    Root exudation, the export of low-molecular weight organic carbon (C) from living plant roots to soil, influences microbial activity, nutrient availability, and ecosystem feedbacks to climate change, but the magnitude of this C flux at ecosystem and global scales is largely unknown. Here, we synthesize in situ measurements of root exudation rates and couple those to estimates of fine root biomass to estimate global and biome-level root exudate C fluxes. We estimate a global root exudate flux of 13.4 (10.1–20.2) Pg C y−1, or about 9% (7–14%) of global annual gross primary productivity. We did not find differences in root mass-specific exudation rates among biomes, though total exudate fluxes are estimated to be greatest in grasslands owing to their high density of absorptive root biomass. Our synthesis highlights the global importance of root exudates in the terrestrial C cycle and identifies regions where more in situ measurements are needed to improve future estimates of root exudate C fluxes

    Identification of a protein encoded in the EB-viral open reading frame BMRF2

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    Using monospecific rabbit sera against a peptide derived from a potential antigenic region of the Epstein-Barr viral amino acid sequence encoded in the open reading frame BMRF2 we could identify a protein-complex of 53/55 kDa in chemically induced B95-8, P3HR1 and Raji cell lines. This protein could be shown to be membrane-associated, as predicted by previous computer analysis of the secondary structure and hydrophilicity pattern, and may be a member of EBV-induced membrane proteins in lytically infected cells

    High (but Not Low) Urinary Iodine Excretion Is Predicted by Iodine Excretion Levels from Five Years Ago

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    Background: It has not been investigated whether there are associations between urinary iodine (UI) excretion measurements some years apart, nor whether such an association remains after adjustment for nutritional habits. The aim of the present study was to investigate the relation between iodine-creatinine ratio (ICR) at two measuring points 5 years apart. Methods: Data from 2,659 individuals from the Study of Health in Pomerania were analyzed. Analysis of covariance and Poisson regressions were used to associate baseline with follow-up ICR. Results: Baseline ICR was associated with follow-up ICR. Particularly, baseline ICR >300 mu g/g was related to an ICR >300 mu g/g at follow-up (relative risk, RR: 2.20; p < 0.001). The association was stronger in males (RR: 2.64; p < 0.001) than in females (RR: 1.64; p = 0.007). In contrast, baseline ICR <100 mu g/g was only associated with an ICR <100 mu g/g at follow-up in males when considering unadjusted ICR. Conclusions: We detected only a weak correlation with respect to low ICR. Studies assessing iodine status in a population should take into account that an individual with a low UI excretion in one measurement is not necessarily permanently iodine deficient. On the other hand, current high ICR could have been predicted by high ICR 5 years ago. Copyright (C) 2011 S. Karger AG, Base

    Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry A1A_1

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    Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1A_1. Longitudinally polarised positrons were scattered off a longitudinally polarised hydrogen target for values of Q2Q^2 between 1.2 and 12 GeV2^2 and values of W2W^2 between 1 and 4 GeV2^2. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable xx. This finding implies that the description of A1A_1 in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of Q2Q^2 above 1.6 GeV2^2.Comment: 5 pages, 1 eps figure, table added, new references added, in print in Phys. Rev. Let

    Dynamics of initial carbon allocation after drought release in mature Norway spruce—Increased belowground allocation of current photoassimilates covers only half of the carbon used for fine‐root growth

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    After drought events, tree recovery depends on sufficient carbon (C) allocation to the sink organs. The present study aimed to elucidate dynamics of tree-level C sink activity and allocation of recent photoassimilates (Cnew_{new}) and stored C in c. 70-year-old Norway spruce (Picea abies) trees during a 4-week period after drought release. We conducted a continuous, whole-tree 13^{13}C labeling in parallel with controlled watering after 5 years of experimental summer drought. The fate of Cnew_{new} to growth and CO2_{2} efflux was tracked along branches, stems, coarse- and fine roots, ectomycorrhizae and root exudates to soil CO2_{2} efflux after drought release. Compared with control trees, drought recovering trees showed an overall 6% lower C sink activity and 19% less allocation of Cnew_{new} to aboveground sinks, indicating a low priority for aboveground sinks during recovery. In contrast, fine-root growth in recovering trees was seven times greater than that of controls. However, only half of the C used for new fine-root growth was comprised of Cnew_{new} while the other half was supplied by stored C. For drought recovery of mature spruce trees, in addition to Cnew_{new}, stored C appears to be critical for the regeneration of the fine-root system and the associated water uptake capacity

    The Q^2-Dependence of Nuclear Transparency for Exclusive ρ0\rho^0 Production

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    Exclusive coherent and incoherent electroproduction of the ρ0\rho^0 meson from 1^1H and 14^{14}N targets has been studied at the HERMES experiment as a function of coherence length (lcl_c), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (Q2-Q^2). The ratio of 14^{14}N to 1^1H cross sections per nucleon, known as nuclear transparency, was found to increase (decrease) with increasing coherence length for coherent (incoherent) ρ0\rho^0 electroproduction. For fixed coherence length, a rise of nuclear transparency with Q2Q^2 is observed for both coherent and incoherent ρ0\rho^0 production, which is in agreement with theoretical calculations of color transparency.Comment: 5 pages, 4 figure
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