Long-Range, Polymer Chain Dynamics of a "Stiff" Polymer. Fluorescence from Poly(isobutylene-alt-maleic anhydride) with N-(1-Pyrenylmethyl)succinimide Groups

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Macromolecules, copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see https://dx.doi.org/10.1021/acs.macromol.7b00527The steady-state fluorescence (SSF) spectra and time resolved fluorescence (TRF) decays of five poly(isobutylene-alt-maleic anhydride) copolymers (PIMA), randomly labeled with N-(1-pyrenyl methyl)succinimide groups (Py-PIMA), have been analyzed in order to describe their long-range, polymer chain dynamics (LRPCD) and to assess the stiffness of the PIMA backbone compared to that of a series of poly(alkyl methacrylate)s whose LRPCD had already been investigated. The SSF spectra, recorded under dilute concentration conditions where only intrachain events are important, show that the intensity ratio of pyrenyl excimer to pyrenyl monomer emission (i.e., (I-E/I-m)(SSF)) increases linearly with increasing pyrenyl content as a result of increased pyrenyl pyrenyl contacts and diffusive encounters. The slope of the straight line, m(I-E/I-M), that reflected the efficiency of pyrenyl excimer formation for Py-PIMA, was found to be 60% smaller than for even poly(octadecyl methacrylate) (PC18MA), a polymer exhibiting slow LRPCD due to its long, bulky side chain. Analyses of the SSF spectra allowed separation of the averaged behavior of five different pyrenyl species in the Py-PIMA polymers, although only two of them were reflected in the LRPCD of PIMA. In addition, the fluorescence decays of the pyrenyl monomer and excimer, when fitted globally according to the model free analysis (MFA), yielded the average rate constant (blob) of pyrenyl excimer formation that directly represents the LRPCD of Py-PIMA. After having conducted two tests that confirmed the validity of the parameters retrieved from the MFA of the TRF decays, (blob) for Py-PIMA was compared to (blob) of nine other polymers. The result of this comparison leads us to conclude that the PIMA backbone is extremely stiff in THF. This study demonstrates the ability of the MFA of fluorescence decays acquired from polymers randomly labeled with pyrenyl groups to characterize quantitatively the LRPCD of even extremely stiff polymers.Division of Chemistry: CHE-1502856Department of Education, Fujian ProvinceNatural Sciences and Engineering Research Council of CanadaNational Natural Science Foundation of China: 2117103

Community-developed checklists for publishing images and image analysis

Images document scientific discoveries and are prevalent in modern biomedical research. Microscopy imaging in particular is currently undergoing rapid technological advancements. However for scientists wishing to publish the obtained images and image analyses results, there are to date no unified guidelines. Consequently, microscopy images and image data in publications may be unclear or difficult to interpret. Here we present community-developed checklists for preparing light microscopy images and image analysis for publications. These checklists offer authors, readers, and publishers key recommendations for image formatting and annotation, color selection, data availability, and for reporting image analysis workflows. The goal of our guidelines is to increase the clarity and reproducibility of image figures and thereby heighten the quality of microscopy data is in publications.Comment: 28 pages, 8 Figures, 3 Supplmentary Figures, Manuscript, Essential recommendations for publication of microscopy image dat

Mechanisms of the reaction pi^-p --> a^0_0(980)n --> p-^0 eta n at high energies

The main dynamical mechanisms of the reaction $\pi^-p \rightarrow a^0_0 (980)n \rightarrow \pi^0\eta n$ at high energies, currently investigated at Serpukhov and Brookhaven, are considered in detail. It is shown that the observed forward peak in its differential cross section can be explained within the framework of the Regge pole model only by the conspiring $\rho_2$ Regge pole exchange. The tentative estimates of the absolute $\pi^-p \rightarrow a^0_0(980)n \rightarrow \pi^0\eta n$ reaction cross section at $P_{lab}^{\pi^-} = 18$ GeV/c are obtained: $\sigma\approx200$ nb and, in the forward direction, $d\sigma/dt\approx940$ nb/GeV$^2$. The contribution of the one pion exchange, which is forbidden by $G$-parity and which can rise owing to the $f^0_0(980)-a^0_0(980)$ mixing, is also estimate. A role of the Regge cuts in the non-flip helicity amplitude is briefly examined and a conclusion is made that the contributions of the cuts have to be inessential in comparison with the conspiring $\rho_2$ Regge pole exchange.Comment: 14 pages, Latex, 2 ps figure

Detecting Starting Point Bias in Dichotomous-Choice Contingent Valuation Surveys

We examine starting point bias in CV surveys with dichotomous choice payment questions and follow-ups, and double-bounded models of the WTP responses. We wish to investigate (1) the seriousness of the biases for the location and scale parameters of WTP in the presence of starting point bias; (2) whether or not these biases depend on the distribution of WTP and on the bids used; and (3) how well a commonly used diagnostic for starting point bias - a test of the null that bid set dummies entered in the right-hand side of the WTP model are jointly equal to zero - performs under various circumstances. Because starting point bias cannot be separately identified in any reliable manner from biases caused by model specification, we use simulation approaches to address this issue. Our Monte Carlo simulations suggest that the effect of ignoring starting point bias is complex and depends on the true distribution of WTP. Bid set dummies tend to soak up misspecifications in the distribution assumed by the researcher for the latent WTP, rather than capturing the presence of starting point bias. Their power in detecting starting point bias is low

Simulating the Impact on the Local Economy of Alternative Management Scenarios for Natural Areas

This working paper estimates the impact on the local economy of the High Garda Natural Park of alternative management scenarios for the West Garda Regional Forest. The local economy is specialized in tourist services and strongly linked to the tourist presence and their level of expenditure. We wish to investigate the effects of the participative management strategy, which takes into account users preferences and the non-participative strategy, using the SAM multiplier analysis. The local SAM has been constructed considering three sectors: agriculture, tourism and a third aggregate sector including all the other activities. The resident population has been divided into two categories: residents employed in the tourist sector and the remaining resident population. The SAM analysis shows that the accounting representation of the local economy is meaningful and that the participative program, if chosen by the central regional management, would be the most desirable program also at the local level

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This paper analyses strategic bargaining in negotiations between non-monolithic players, i.e. agents starting negotiations can split up in smaller entities during the bargaining process. We show that the possibility of scission in the informed coalition implies that it loses its information advantages. We also show that when the possibility of a scission exists the uninformed player does not focus on his or her beliefs about the strength of the informed coalition but on the proportion of weak/strong players within this coalition. Finally, our results show that the possibility of a scission reduces the incentives for the leader to propose a high offer to ensure a global agreement. We apply this framework to international negotiations on global public goods and to wage negotiations

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We use contingent valuation to elicit WTP for a reduction in the risk of dying for cardiovascular and respiratory causes, the most important causes of premature mortality associated with heat wave and air pollution, among the Italian public. The purpose of this study is three-fold. First, we obtain WTP and VSL figures that can be applied when estimating the benefits of heat advisories, other policies that reduce the mortality effects of extreme heat, and environmental policies that reduce the risk of dying for cardiovascular and respiratory causes. Second, our experimental study design allows us to examine the sensitivity of WTP to the size of the risk reduction. Third, we examine whether the WTP of populations that are especially sensitive to extreme heat and air pollution - such as the elderly, those in compromised health, and those living alone and/or physically impaired - is different from that of other individuals. We find that WTP, and hence the VSL, depends on the risk reduction, respondent age (via the baseline risk), and respondent health status. WTP increases with the size of the risk reduction, but is not strictly proportional to it. All else the same, older individuals are willing to pay less for a given risk reduction than younger individuals of comparable characteristics. Poor health, however, tends to raise WTP, so that the appropriate VSL of elderly individuals in poor health may be quite large. Our results support the notion that the VSL is individuated