283 research outputs found

    OPTIMAL GRADE DEFINITIONS FOR MULTIPLE QUALITY CHARACTERISTICS

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    The growing importance of quality in agricultural markets makes effective segregation and grading essential to efficient marketing strategy. In this paper, we develop an economic model, potentially applicable to many products, to determine optimal segregation strategies based on multiple stochastic quality measures. The model is applied to Oklahoma wheat quality data.Marketing,

    X-ray investigation of lateral hetero-structures of inversion domains in LiNbO3, KTiOPO4 and KTiOAsO4

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    In this paper periodically domain-inverted (PDI) ferroelectric crystals are studied using high-resolution X-ray diffraction. Rocking curves and reciprocal-space maps of the principal symmetric Bragg reflections in LiNbO3 (LN) (Λ = 5μm), KTiOPO4 (KTP) (Λ = 9μm) and KTiOAsO4 (KTA) (Λ = 39μm) are presented. For all the samples strong satellite reflections were observed as a consequence of the PDI structure. Analysis of the satellites showed that they were caused by a combination of coherent and incoherent scattering between the adjacent domains. Whilst the satellites contained phase information regarding the structure of the domain wall, this information could not be rigorously extracted without a priori knowledge of the twinning mechanism. Analysis of the profiles reveals strain distributions of Δd/d = 1.6 × 10-4 and 2.0 × 10-4 perpendicular to domain walls in KTP and LN samples, respectively, and lateral correlation lengths of 63μm (KTP), 194μm (KTA) and 10μm (LN). The decay of crystal truncation rods in LN and KTP was found to support the occurrence of surface corrugations

    The quantitative soil pit method for measuring belowground carbon and nitrogen stocks

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    Many important questions in ecosystem science require estimates of stocks of soil C and nutrients. Quantitative soil pits provide direct measurements of total soil mass and elemental content in depth-based samples representative of large volumes, bypassing potential errors associated with independently measuring soil bulk density, rock volume, and elemental concentrations. The method also allows relatively unbiased sampling of other belowground C and nutrient stocks, including roots, coarse organic fragments, and rocks. We present a comprehensive methodology for sampling these pools with quantitative pits and assess their accuracy, precision, effort, and sampling intensity as compared to other methods. At 14 forested sites in New Hampshire, nonsoil belowground pools (which other methods may omit, double-count, or undercount) accounted for upward of 25% of total belowground C and N stocks: coarse material accounted for 4 and 1% of C and N in the O horizon; roots were 11 and 4% of C and N in the O horizon and 10 and 3% of C and N in the B horizon; and soil adhering to rocks represented 5% of total B-horizon C and N. The top 50 cm of the C horizon contained the equivalent of 17% of B-horizon carbon and N. Sampling procedures should be carefully designed to avoid treating these important pools inconsistently. Quantitative soil pits have fewer sources of systematic error than coring methods; the main disadvantage is that because they are time-consuming and create a larger zone of disturbance, fewer observations can be made than with cores

    Putting policy into practice: how three cancer services perform against indigenous health and cancer frameworks

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    Improving cancer outcomes for Indigenous people by providing culturally safe, patient-centred care is a critical challenge for health services worldwide. This article explores how three Australian cancer services perform when compared to two national best practice guidelines: the National Aboriginal and Torres Strait Islander Cancer Framework (Cancer Framework) and the National Safety and Quality Health Service (NSQHS) User Guide for Aboriginal and Torres Strait Islander Health (User Guide). The services were identified through a nationwide project undertaken to identify cancer services providing treatment to Indigenous cancer patients. A small number of services which were identified as particularly focused on providing culturally safe cancer care participated in case studies. Interviews were conducted with 35 hospital staff (Indigenous and non-Indigenous) and 8 Indigenous people affected by cancer from the three services. The interviews were analysed and scored using a traffic light system according to the seven priorities of the Cancer Framework and the six actions of the NSQHS User Guide. While two services performed well against the User Guide, all three struggled with the upstream elements of the Cancer Framework, suggesting that the treatment-focused Optimal Care Pathway for Aboriginal and Torres Strait Islander People with Cancer (Cancer Pathway) may be a more appropriate framework for tertiary services. This article highlights the importance of a whole-of-organisation approach when addressing and embedding the six actions of the User Guide. Health services which have successfully implemented the User Guide are in a stronger position to implement the Cancer Framework and Cancer Pathway.Emma V. Taylor, Marilyn Lyford, Lorraine Parsons, Michele Holloway, Karla Gough, Sabe Sabesan and Sandra C. Thompso

    Methamphetamine induces endoplasmic reticulum stress related gene CHOP/Gadd153/ddit3 in dopaminergic cells

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    We examined the toxicity of methamphetamine and dopamine in CATH.a cells, which were derived from mouse dopamine-producing neural cells in the central nervous system. Use of the quantitative real-time polymerase chain reaction revealed that transcripts of the endoplasmic reticulum stress related gene (CHOP/Gadd153/ddit3) were considerably induced at 24–48 h after methamphetamine administration (but only under apoptotic conditions), whereas dopamine slightly induced CHOP/Gadd153/ddit3 transcripts at an early stage. We also found that dopamine and methamphetamine weakly induced transcripts for the glucose-regulated protein 78 gene (Grp78/Bip) at the early stage. Analysis by immunofluorescence microscopy demonstrated an increase of CHOP/Gadd153/ddit3 and Grp78/Bip proteins at 24 h after methamphetamine administration. Treatment of CATH.a cells with methamphetamine caused a re-distribution of dopamine inside the cells, which mimicked the presynaptic activity of neurons with cell bodies located in the ventral tegmental area or the substantia nigra. Thus, we have demonstrated the existence of endoplasmic reticulum stress in a model of presynaptic dopaminergic neurons for the first time. Together with the recent evidence suggesting the importance of presynaptic toxicity, our findings provide new insights into the mechanisms of dopamine toxicity, which might represent one of the most important mechanisms of methamphetamine toxicity and addiction

    Conformational changes in α7 acetylcholine receptors underlying allosteric modulation by divalent cations

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    Allosteric modulation of membrane receptors is a widespread mechanism by which endogenous and exogenous agents regulate receptor function. For example, several members of the nicotinic receptor family are modulated by physiological concentrations of extracellular calcium ions. In this paper, we examined conformational changes underlying this modulation and compare these with changes evoked by ACh. Two sets of residues in the α7 acetylcholine receptor extracellular domain were mutated to cysteine and analyzed by measuring the rates of modification by the thiol-specific reagent 2-aminoethylmethane thiosulfonate. Using Ba2+ as a surrogate for Ca2+, we found a divalent-dependent decrease the modification rates of cysteine substitutions at M37 and M40, residues at which rates were also slowed by ACh. In contrast, Ba2+ had no significant effect at N52C, a residue where ACh increased the rate of modification. Thus divalent modulators cause some but not all of the conformational effects elicited by agonist. Cysteine substitution of either of two glutamates (E44 or E172), thought to participate in the divalent cation binding site, caused a loss of allosteric modulation, yet Ba2+ still had a significant effect on modification rates of these residues. In addition, the effect of Ba2+ at these residues did not appear to be due to direct occlusion. Our data demonstrate that modulation by divalent cations involves substantial conformational changes in the receptor extracellular domain. Our evidence also suggests the modulation occurs via a binding site distinct from one which includes either (or both) of the conserved glutamates at E44 or E172

    Huntingtin mediates dendritic transport of β-actin mRNA in rat neurons

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    Transport of mRNAs to diverse neuronal locations via RNA granules serves an important function in regulating protein synthesis within restricted sub-cellular domains. We recently detected the Huntington's disease protein huntingtin (Htt) in dendritic RNA granules; however, the functional significance of this localization is not known. Here we report that Htt and the huntingtin-associated protein 1 (HAP1) are co-localized with the microtubule motor proteins, the KIF5A kinesin and dynein, during dendritic transport of β-actin mRNA. Live cell imaging demonstrated that β-actin mRNA is associated with Htt, HAP1, and dynein intermediate chain in cultured neurons. Reduction in the levels of Htt, HAP1, KIF5A, and dynein heavy chain by lentiviral-based shRNAs resulted in a reduction in the transport of β-actin mRNA. These findings support a role for Htt in participating in the mRNA transport machinery that also contains HAP1, KIF5A, and dynein

    Loss of Arc renders the visual cortex impervious to the effects of sensory experience or deprivation

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    A myriad of mechanisms have been suggested to account for the full richness of visual cortical plasticity. We found that visual cortex lacking Arc is impervious to the effects of deprivation or experience. Using intrinsic signal imaging and chronic visually evoked potential recordings, we found that Arc−/− mice did not exhibit depression of deprived-eye responses or a shift in ocular dominance after brief monocular deprivation. Extended deprivation also failed to elicit a shift in ocular dominance or open-eye potentiation. Moreover, Arc−/− mice lacked stimulus-selective response potentiation. Although Arc−/− mice exhibited normal visual acuity, baseline ocular dominance was abnormal and resembled that observed after dark-rearing. These data suggest that Arc is required for the experience-dependent processes that normally establish and modify synaptic connections in visual cortex.Howard Hughes Medical InstituteNational Science Foundation (U.S.

    Selective Survival and Maturation of Adult-Born Dentate Granule Cells Expressing the Immediate Early Gene Arc/Arg3.1

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    Progenitor cells in the adult dentate gyrus provide a constant supply of neuronal precursors, yet only a small fraction of these cells survive and develop into mature dentate granule cells (DGCs). A major challenge of current research is thus to understand the stringent selection process that governs the maturation and functional integration of adult-born DGCs. In mature DGCs, high-frequency stimulation (HFS) of the perforant path input elicits robust expression of the immediate early gene Arc/Arg3.1, trafficking of its mRNA to dendrites, and local synthesis of the protein necessary for consolidation of long-term potentiation (LTP). Given the synaptic commitment inherent in LTP consolidation, we considered that HFS-evoked expression of Arc could be used to timemap the functional integration of newborn DGCs. Dividing cells were birthmarked by BrdU-labeling at 1, 7, 14, 21, or 28 days prior to induction of LTP and expression of Arc was examined by confocal microscopy. Contrary to expectation, LTP did not induce Arc expression in newborn cells at any age, suggesting they might be refractory to synaptically-evoked Arc expression for at least one month. Importantly, however, spontaneous expression of Arc was detected in BrdU-labeled cells and strongly associated with the survival and maturation of NeuN-positive DGCs. Moreover, Arc expression at the earliest ages (1 and 7 days), clearly precedes the formation of glutamatergic synapses on new neurons. These results suggest an unexpected early role for Arc in adult-born DGCs, distinct from its functions in LTP, LTD, and homeostatic synaptic plasticity
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