5,374 research outputs found

    The ammonolysis of esters in liquid ammonia

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    The rates of ammonolysis of alkyl benzoate and phenylacetate esters in liquid ammonia increase with the acidity of the leaving group alcohol and show relatively large Brønsted βlg values of −1.18 and −1.34, respectively, when plotted against the aqueous pKa of the alcohol. The Brønsted βlg obtained using the pKa of the leaving group alcohol in liquid ammonia is significantly reduced to ~ −0.7, which indicates that the rate-limiting step involves a reaction of the tetrahedral intermediate with little C–OR bond fission in the transition state. The solvolysis reaction is subject to significant catalysis by ammonium ion, which, surprisingly, generates a similar Brønsted βlg indicating little interaction between the ammonium ion and the leaving group. It is concluded that the rate-limiting step for the ammonium-ion-catalysed solvolysis of alkyl esters in liquid ammonia is the diffusion-controlled protonation of the zwitterionic tetrahedral intermediate T+- to give T+, which is rapidly deprotonated to give T0 which is compatible with the rate-limiting step for the uncatalysed reaction being the formation of the neutral T0 by a ‘proton switc

    The “Name Game”: Affective and Hiring Reactions to First Names

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    Purpose – The paper seeks to examine how the uniqueness and ethnicity of first names influence affective reactions to those names and their potential for hire. Design/methodology/approach – In study 1, respondents evaluated 48 names in terms of uniqueness and likeability, allowing us to select names viewed consistently as Common, Russian, African-American, and Unusual. In Study 2 respondents assessed the uniqueness and likeability of the names, and whether they would hire someone with the name. Findings – Results indicated that Common names were seen as least unique, best liked, and most likely to be hired. Unusual names were seen as most unique, least liked, and least likely to be hired. Russian and African-American names were intermediate in terms of uniqueness, likeability and being hired, significantly different from Common and Unique names, but not significantly different from each other. Research limitations/implications – The name an individual carries has a significant impact on how he or she is viewed, and conceivably, whether or not the individual is hired for a job. Practical implications – Human resource professionals need to be aware that there seems to be a clear bias in how people perceive names. When resumés are screened for hiring, names should be left off. Our findings also suggest that when selecting, parents may want to reconsider choosing something distinctive. Originality/value – This study offers original findings in regards to names, combining diverse research from social psychology and labor economics, and offering practical implications

    A general biodiversity-function relationship is mediated by trophic level

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    Species diversity affects the functioning of ecosystems, including the efficiency by which communities capture limited resources, produce biomass, recycle and retain biologically essential nutrients. These ecological functions ultimately support the ecosystem services upon which humanity depends. Despite hundreds of experimental tests of the effect of biodiversity on ecosystem function (BEF), it remains unclear whether diversity effects are sufficiently general that we can use a single relationship to quantitatively predict how changes in species richness alter an ecosystem function across trophic levels, ecosystems and ecological conditions. Our objective here is to determine whether a general relationship exists between biodiversity and standing biomass. We used hierarchical mixed effects models, based on a power function between species richness and biomass production (Y = a × Sb), and a database of 374 published experiments to estimate the BEF relationship (the change in biomass with the addition of species), and its associated uncertainty, in the context of environmental factors. We found that the mean relationship (b = 0.26, 95% CI: 0.16, 0.37) characterized the vast majority of observations, was robust to differences in experimental design, and was independent of the range of species richness levels considered. However, the richness–biomass relationship varied by trophic level and among ecosystems; in aquatic systems b was nearly twice as large for consumers (herbivores and detritivores) compared to primary producers; in terrestrial ecosystems, b for detritivores was negative but depended on few studies. We estimated changes in biomass expected for a range of changes in species richness, highlighting that species loss has greater implications than species gains, skewing a distribution of biomass change relative to observed species richness change. When biomass provides a good proxy for processes that underpin ecosystem services, this relationship could be used as a step in modeling the production of ecosystem services and their dependence on biodiversity

    Communication System For Firefighters

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    Currently firefighters use two-way radios to communicate on the job, and they are forced to write reports based on their memory because there is not an easy way to record the communications between two-way radios. Firefighters need a system to automatically document what happened while they were responding to a call. To save them a significant amount of time when creating reports, our solution is to implement an application that allows firefighters to take pictures, record video and communicate in real time with their team of on-site responders. The proposed system will use a Wireless Local Area Network (WLAN) hosted on the fire truck itself to act as an access point (AP) to which the firefighters can connect. This AP will also save communication between firefighters to a local storage location. Upon return to the fire station, the AP will route all of the information stored locally to a larger database. For now, Wi-Fi will be our communication medium, with a prediction that our technology can eventually be extended to include radio signal

    Proof of the Umbral Moonshine Conjecture

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    The Umbral Moonshine Conjectures assert that there are infinite-dimensional graded modules, for prescribed finite groups, whose McKay-Thompson series are certain distinguished mock modular forms. Gannon has proved this for the special case involving the largest sporadic simple Mathieu group. Here we establish the existence of the umbral moonshine modules in the remaining 22 cases.Comment: 56 pages, to appear in Research in the Mathematical Science

    Book Review: Forrest McDonald\u27s States\u27 Rights and the Union

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    Alien Registration- Griffin, John (Portland, Cumberland County)

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    https://digitalmaine.com/alien_docs/23862/thumbnail.jp

    Doppler radar with multiphase modulation of transmitted and reflected signal

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    A microwave radar signal is generated and split by a circulator. A phase shifter introduces a series of phase shifts into a first part of the split signal which is then transmitted by antenna. A like number of phase shifts is introduced by the phase shifter into the return signal from the target. The circulator delivers the phase shifted return signal and the leakage signal from the circulator to a mixer which generates an IF signal output at the Doppler frequency. The IF signal is amplified, filtered, counted per unit of time, and the result displayed to provide indications of target sense and range rate. An oscillator controls rate of phase shift in the transmitted and received radar signals and provides a time base for the counter. The phase shift magnitude increases may be continuous and linear or discrete functions of time
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