757 research outputs found

    Studies on imino, amidino and related derivatives of some main group elements

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    This thesis describes studies on the co-ordination chemistry of Group II elements, magnesium and zinc, and Group IV elements silicon, germanium and tin. Attention is focussed principally on systems with ligands containing multiple-bonded nitrigen attached t, these Groups II and IV elements viz., Ketimino and amidin, derivatives containing R(_2)C=N and R(^1)NC(R)=NR(^1) ligands respectively. After an introductory survey of the relevant chemistry, Chapter 2 describes studies on fifteen ketiminomagnesium derivatives of formula types (R(_2)C=NMgBr)(_2)(L)(_x), [(R(_2)C=N)(_2)Mg](_n)(THF)(_x), (R(_2)C=NMgX)(_n)L(_m) and includes an X-ray crystal structure of (Ph(_2)C=NMgBr)(_2)(THF)(_3). All compounds described are associated species, often dimeric, and are believed to co-ordinate via bridging methyleneamino ligands with additional bridging ligands (OEt(_2), THF and TMED) in some cases. Where compounds also contain terminally attached methyleneamino ligands, their infrared spectra are consistent with linear C=N-Mg units. Chapter 3 describes related studies on ten methylene- aminozinc compounds of formula types (R(_2)C=NH)(_x)ZnX(_2), R = Ph, p-tolyl, X=C1, X = 2; R=Bu(^t), X = 1, x = 1; R= p-tolyl, X = Ph, X = 1; RCN.ZnPh(_2) (R = p-tolyl); (R(_1)R(_2)C=NZnX)(_n),= R(_2) = p-tolyl, X = Ph, n = 2; R(_2) = Eg = p-tolyl, X = Ph, n = 2; R(_1) = Ph, R(_2) = p-tolyl, X = Ph, n = 2; R(_1) = R(_2) = p-tolyl, X = (p-tolyl)(_2)C=N, The associated species are thought to have bridging methyleneamino units with three-co-ordinate zinc

    Message From the Presidents

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    Kids, Caregivers, and Cartoons: The Impact of Licensed Characters on Food Choices and Consumption

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    This research examines effects of on-package licensed characters on children’s and caregivers’ choices of healthy and indulgent food and children’s consumption amount. The authors propose that food liking exerts the greatest influence on children’s choices and consumption, such that the impact of on-package characters will be limited to choices between equally liked options. Caregivers’ choices are primarily influenced by their food goals for their children; thus, the impact of characters will likewise be limited to caregivers’ within-category choices. Two experiments show that a character influences children’s choices between two same-category options but not between indulgent and healthier options. A third experiment reveals that food liking influences amount consumed, while the presence of a character influences neither amount consumed nor food liking. Two additional experiments show that characters influence caregivers’ choice between the same foods, but not between different food types or intention to purchase a food. The expanded framework for the effects of licensed characters—taking into account choice versus consumption, children versus caregivers, and healthy versus unhealthy foods—enhances understanding for consumers, practitioners, and policy makers

    Bioreactor perfusion via single-use centrifugation has fewer product quality implications than tangential flow filtration

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    During development of a perfusion cell culture process for the production of a therapeutic protein, tangential flow filtration (TFF) technology was evaluated for cell retention in addition to Shire’s platform single-use centrifugation technology. Unlike centrifugation TFF is based on a microfiltration membrane and thus has the potential to partially retain many biological compounds, especially when exposed to extracellular matrix proteins and antifoam emulsions (Routledge, 2012; Wu et al., 2011). Retention increases the mean residence time of product at process temperature. In the case of heat-labile molecules longer exposure to bioreactor culture temperature may correlate with changes in quality attributes. Therapeutic protein was generated from bioreactors equipped with single-use centrifuge and TFF technology for cell retention. Peak viable cell density was slightly higher using TFF, due to the moderate cell loss of centrifugation, but viability by trypan blue exclusion was slightly lower. Metabolic profiles (glucose, lactate, ammonium, glutamate) were not affected by the choice of cell retention technology. Cell specific productivity was similar for both cell retention devices; however, TFF membranes had to be changed periodically to reduce protein retention and thereby achieve the volumetric productivity of the single-use centrifuge. All measured product quality attributes, for both intermediates and drug substance (DS), were comparable between TFF and single-use centrifugation. Nevertheless, drug substance generated from bioreactors equipped with TFF had significantly decreased room-temperature stability compared to DS generated from bioreactors equipped with single-use centrifuges. DS instability of TFF lots, indicated by an increased propensity to generate low molecular weight species (LMW), was more pronounced in later harvests compared to early harvests. Analysis (HPLC-MS & peptide mapping) of degraded drug substance found molecular fragments that corresponded to the subunits of the therapeutic protein. Cleavage occurred at several sites close to the linkage molecules bridging the protein subunits. A literature search for compounds that target the cleavage sites identified metalloproteases and serine proteases as likely agonists for the observed cleavages and serine proteases were detected in a proteomics analysis of both TFF and single-use centrifuge material. While DS lot stability suffered with TFF the stability of process intermediates was found to be similar between TFF and centrifuge lots. If proteases are responsible for the observed LMW generation said proteases might have greater activity when concentrated and/or when inhibitory compounds are removed during purification. It is plausible that TFF may have contributed to either LMW generation in the cell culture or retention of a protectant moiety. Additional study is necessary to confidently posit a root cause

    Enabling Factor Analysis on Thousand-Subject Neuroimaging Datasets

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    The scale of functional magnetic resonance image data is rapidly increasing as large multi-subject datasets are becoming widely available and high-resolution scanners are adopted. The inherent low-dimensionality of the information in this data has led neuroscientists to consider factor analysis methods to extract and analyze the underlying brain activity. In this work, we consider two recent multi-subject factor analysis methods: the Shared Response Model and Hierarchical Topographic Factor Analysis. We perform analytical, algorithmic, and code optimization to enable multi-node parallel implementations to scale. Single-node improvements result in 99x and 1812x speedups on these two methods, and enables the processing of larger datasets. Our distributed implementations show strong scaling of 3.3x and 5.5x respectively with 20 nodes on real datasets. We also demonstrate weak scaling on a synthetic dataset with 1024 subjects, on up to 1024 nodes and 32,768 cores

    Vacuum Strength of Two Candidate Glasses for a Space Observatory

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    The strengths of two candidate glass types for use in a space observatory were measured. Samples of ultra-low expansion glass (ULE) and borosilicate (Pyrex) were tested in air and in vacuum at room temperature (20 degrees C) and in vacuum after being heated to 200 degrees C. Both glasses tested in vacuum showed a significant increase in strength over those tested in air. However, there was no statistical difference between the strength of samples tested in vacuum at room temperature and those tested in vacuum after heating to 200 degrees C

    Faster Phrase-Based Decoding by Refining Feature State

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    We contribute a faster decoding algo-rithm for phrase-based machine transla-tion. Translation hypotheses keep track of state, such as context for the language model and coverage of words in the source sentence. Most features depend upon only part of the state, but traditional algorithms, including cube pruning, handle state atom-ically. For example, cube pruning will re-peatedly query the language model with hypotheses that differ only in source cov-erage, despite the fact that source cover-age is irrelevant to the language model. Our key contribution avoids this behav-ior by placing hypotheses into equivalence classes, masking the parts of state that matter least to the score. Moreover, we ex-ploit shared words in hypotheses to itera-tively refine language model scores rather than handling language model state atom-ically. Since our algorithm and cube prun-ing are both approximate, improvement can be used to increase speed or accuracy. When tuned to attain the same accuracy, our algorithm is 4.0–7.7 times as fast as the Moses decoder with cube pruning.

    A SQUAMOSA MADS-box gene involved in the regulation of anthocyanin accumulation in bilberry fruits

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    Anthocyanins are important health promoting phytochemicals that are abundant in many fleshy fruits. Bilberry (Vaccinium myrtillus L.) is one of the best sources of these compounds. Here we report on the expression pattern and functional analysis of a SQUAMOSA (SQUA) class MADS-box transcription factor, VmTDR4, associated with anthocyanin biosynthesis in bilberry. Levels of VmTDR4 expression were spatially and temporally linked with colour development and anthocyanin-related gene expression. Virus induced gene silencing (VIGS) was used to suppress VmTDR4 expression in bilberry resulting in substantial reduction in anthocyanin levels in fully ripe fruits. Chalcone synthase was used a positive control in the VIGS experiments. Additionally, in sectors of fruit tissue in which the expression of the VmTDR4 gene was silenced, the expression of R2R3 MYB family transcription factors related to the biosynthesis of flavonoids were also altered. We conclude that VmTDR4 plays an important role in the accumulation of anthocyanins during normal ripening in bilberry; probably through direct or indirect control of transcription factors belonging to the R2R3 MYB family

    Selection on moral hazard in health insurance

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    We use employee-level panel data from a single rm to explore the possibility that individuals may select insurance coverage in part based on their anticipated behavioral ( moral hazard ) response to insurance, a phenomenon we label selection on moral hazard. Using a model of plan choice and medical utilization, we present evidence of heterogeneous moral hazard as well as selection on it, and explore some of its implica- tions. For example, we show that, at least in our context, abstracting from selection on moral hazard could lead to over-estimates of the spending reduction associated with introducing a high-deductible health insurance option.National Institute on Aging (NIA (R01 AG032449))National Cancer Institute (U.S.) (Grant SES-0643037)United States. Social Security Administration (grant #5 RRC08098400-03-00)Aluminum Company of AmericaAlfred P. Sloan FoundationJohn D. and Catherine T. MacArthur Foundation (Network on Socioeconomic Status and Health
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