908 research outputs found

    The effect of rate of nitrogen fertilization, geographic location, and date of harvest on yield, acceptability, and nutritive value of timothy hay, Station Bulletin, no.486

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    The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire

    Nutritive value of dried beet pulp, Station Bulletin, no.477

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    The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire

    The nutritive value of dried citrus pulp for dairy cattle, Station Bulletin, no.438

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    The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire

    The effect of texture on the nutritive value of concentrates for dairy cattle, Station Bulletin, no.419

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    The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire

    Influence of Acid Washing on the Surface Morphology of Ionomer Glasses and Handling Properties of Glass Ionomer Cements

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    Acid washing is known to influence the handling properties of ionomer glasses used in glass ionomer cements due to the production of an ion depleted zone on the surface of the glass particles. The influence of acid washing on the particle size distribution and surface area of four glasses was examined by scanning electron microscopy (SEM), particle size analysis (PSA) and accelerated surface area porosimetry (ASAP) and the working and setting times of cements, produced from the glasses, correlated to changes in surface morphology. A linear relationship was found between the specific surface area of acid-washed SiO2-Al2O3-XF2-P2O5 glasses (X being either calcium or strontium) and their cement working and setting times. These changes directly correlated with increases in the mesopore volume. However, the influence of acid washing on the surface morphology was also found to be glass composition-dependant with the addition of sodium into the glass network resulting in no significant change in the surface area or mesopore volume despite changes in the working and setting time. Through examination of the influence of acid washing and glass composition on the specific surface area improvements in the control of the working and setting times of glass ionomer cements may be achieved. © 2007 Springer Science+Business Media, LLC

    Network mechanisms of intentional learning.

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    The ability to learn new tasks rapidly is a prominent characteristic of human behaviour. This ability relies on flexible cognitive systems that adapt in order to encode temporary programs for processing non-automated tasks. Previous functional imaging studies have revealed distinct roles for the lateral frontal cortices (LFCs) and the ventral striatum in intentional learning processes. However, the human LFCs are complex; they house multiple distinct sub-regions, each of which co-activates with a different functional network. It remains unclear how these LFC networks differ in their functions and how they coordinate with each other, and the ventral striatum, to support intentional learning. Here, we apply a suite of fMRI connectivity methods to determine how LFC networks activate and interact at different stages of two novel tasks, in which arbitrary stimulus-response rules are learnt either from explicit instruction or by trial-and-error. We report that the networks activate en masse and in synchrony when novel rules are being learnt from instruction. However, these networks are not homogeneous in their functions; instead, the directed connectivities between them vary asymmetrically across the learning timecourse and they disengage from the task sequentially along a rostro-caudal axis. Furthermore, when negative feedback indicates the need to switch to alternative stimulus-response rules, there is additional input to the LFC networks from the ventral striatum. These results support the hypotheses that LFC networks interact as a hierarchical system during intentional learning and that signals from the ventral striatum have a driving influence on this system when the internal program for processing the task is updated.This work was supported by Medical Research Council Grant (U1055.01.002.00001.01) and a European Research GrantPCIG13-GA-2013-618351 to AH. JBR is supported by the Wellcome Trust (103838). The authors report no conflicts of interest.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neuroimage.2015.11.06

    Out of the boxes, out of the silos: The need of interdisciplinary collaboration to reduce poor-quality medical products in the supply chain

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    In this paper, we argue that understanding and addressing the problem of poor-quality medical products requires a more interdisciplinary approach than has been evident to date. While prospective studies based on rigorous standardized methodologies are the gold standard for measuring the prevalence of poor-quality medical products and understanding their distribution nationally and internationally, they should be complemented by social science research to unpack the complex set of social, economic, and governance factors that underlie these patterns. In the following sections, we discuss specific examples of prospective quality surveys and of social science studies, highlighting the value of cross-sector partnerships in driving high-quality, policy-relevant research in this area

    Striatum in stimulus-response learning via feedback and in decision making.

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    Cognitive deficits are recognized in Parkinson\u27s disease. Understanding cognitive functions mediated by the striatum can clarify some of these impairments and inform treatment strategies. The dorsal striatum, a region impaired in Parkinson\u27s disease, has been implicated in stimulus-response learning. However, most investigations combine acquisition of associations between stimuli, responses, or outcomes (i.e., learning) and expression of learning through response selection and decision enactment, confounding these separate processes. Using neuroimaging, we provide evidence that dorsal striatum does not mediate stimulus-response learning from feedback but rather underlies decision making once associations between stimuli and responses are learned. In the experiment, 11 males and 5 females (mean age 22) learned to associate abstract images to specific button-press responses through feedback in Session 1. In Session 2, they were asked to provide responses learned in Session 1. Feedback was omitted, precluding further feedback-based learning in this session. Using functional magnetic resonance imaging, dorsal striatum activation in healthy young participants was observed at the time of response selection and not during feedback, when greatest learning presumably occurs. Moreover, dorsal striatum activity increased across the duration of Session 1, peaking after most associations were well learned, and was significant during Session 2 where no feedback was provided, and therefore no feedback-based learning occurred. Preferential ventral striatum activity occurred during feedback and was maximal early in Session 1. Taken together, the results suggest that the ventral striatum underlies learning associations between stimuli and responses via feedback whereas the dorsal striatum mediates enacting decisions
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