493 research outputs found

    Do editors favor their students' work? A test of undue favoritism in top economics journals

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    This paper asks whether students with top journal editors as dissertation advisors observe statistical advantages in publishing over students without top journal editors as dissertation advisors. We analyze early-career publication histories of nearly 2,000 graduates from top 30 economics programs in the early 1990s. We find that students who work with QJE editors average significantly higher values over four common measures of general research productivity than otherwise similar students and that students of QJE editors average significantly more AER and QJE publications. We further find that both students of ReStat editors and students of Econometrica editors average statistically more ReStat articles. Our results appear to reject the argument that top journal editors exhibit undue favoritism in the publication process with regards to their former students.Dissertation Advisor; Research Productivity

    A DESCRIPTIVE AND ECONOMETRIC ANALYSIS OF ANNUAL SALARIES, GENDER, EXPERIENCE, AND PEER-REVIEWED PUBLICATION HISTORIES WITHIN TOP-RANKED AGRICULTURAL ECONOMICS PROGRAMS

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    Utilizing an original data set containing annual salaries and peer-reviewed publication histories for 328 faculty members we examine the labor market for academic agricultural economists. Our descriptive analysis shows that while the profession remains male-dominated, females are making significant inroads at the lower academic ranks, the profession is relatively top-heavy, with nearly two-thirds of the faculty in our data set currently holding the rank of full professor, differences in annual salary exist primarily for faculty at Top 6 programs, and then primarily for full professors. Our regression analysis suggests that controlling for publication history there are neither statistically significant negative returns to increased tenure nor statistically significant negative returns to gender, holding all else constant.Teaching/Communication/Extension/Profession,

    ON THE RETURN TO JOURNAL QUALITY, COAUTHORSHIP AND AUTHOR ORDER WITHIN TOP RANKED AGRICULTURAL ECONOMICS PROGRAMS

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    Utilizing an original data set containing annual salaries and peer-reviewed publication histories for 326 faculty members from top-ranked Ph.D.-granting programs we examine the labor market for academic agricultural economists. The results suggest that higher quality publications have a greater impact on annual earnings, that sole authored articles have a higher return than multi-authored articles and that no wage premium exists for being the lead author of a non-alphabetic paper.Teaching/Communication/Extension/Profession,

    An Examination of the Feasibility of Linear Deterministic Sea Wave Prediction in Multi-Directional Seas Using Wave Profiling Radar: Theory, Simulation and Sea Trials

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    This is the final version of the article. Available from the American Meteorological Society via the DOI in this record.For a number of maritime tasks there is a short time period, typically only a few tens of seconds, where a critical event occurs which defines a limiting wave height for the whole operation. Examples are the recovery of fixed and rotary winged aircraft, cargo transfers, final pipe mating in fluid transfer operations and launch/recovery of small craft. The recovery of a 30 ton rescue submersible onto a mother ship in the NATO Submarine Rescue System is a prime example. In such applications short term Deterministic Sea Wave Prediction (DSWP) can play a vital role in extending the sea states under which the system can be safely deployed. DSWP also has great potential in conducting experimental sea wave research at full scale. This report explores the feasibility of using data from an experimental wave profiling radar in achieving DSWP. The report includes theory, simulation and field testing. Two forms of DSWP are employed, a fixed point system based upon a restricted set of wave directions, from which we obtain some success, and the other a fully two dimensional technique, which requires further development. The main finding is that using wave profiling radar for DSWP offers promise but requires improvements both to the spatial reliability and resolution of the wave profiling radar, and to the temporal resolution of its sweep before the technique can be considered to be viable as a usable tool.The authors acknowledge funding from the European Union FP7 and U.K. Ministry of Defence NSRS projects

    Engineering nanocarbon interfaces for electron transfer

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 131-141).Electron-transfer reactions at nanometer-scale interfaces, such as those presented by single-walled carbon nanotubes (SWCNTs), are important for emerging optoelectronic and photovoltaic technologies. Electron transfer also governs a primary means by which these interfaces are chemically functionalized and subsequently manipulated. This thesis explores several chemical approaches to understanding and controlling charge transfer at nanocarbon interfaces. In the first part of this thesis, we explore ground-state electron transfer via the chemical reaction of SWCNTs with selected diazonium salts as a means of controlling the number of moieties attached to a given nanotube. We initially explore this reaction theoretically using a kinetic Monte Carlo simulation, with rate parameters evaluated using Gerischer-Marcus theory, in order to examine the extent to which these reactions can be controlled stoichiometrically. These modeling results indicate that heterogeneities in SWCNT chiral population result in a large variance in the number of covalent defects, even at low conversions, thereby limiting the ability to control these reactions through stoichiometry. We then experimentally examine the ability to impart an additional degree of control over these reactions through utilization of the adsorbed surfactant layer. Surfactants are commonly employed in the processing of nanoparticles to impart colloidal stability to otherwise unstable dispersions. We find that the chemical and physical properties of adsorbed surfactants influence the diazonium reaction with SWCNT in several ways. Surfactants can impose electrostatic attraction or repulsion, steric exclusion, and direct chemical modification of the reactant. Electrostatic effects are most pronounced in the cases of anionic sodium dodecyl sulfate and cationic cetyltrimethylammonium bromide, where differences in surfactant charge can significantly affect the ability of the diazonium ion to access the SWCNT surface. For bile salt surfactants, with the exception of sodium cholate, we find that the surfactant wraps tightly enough that exclusion effects are dominant. Here, sodium taurocholate exhibits almost no reactivity under the explored reaction conditions, while for sodium deoxycholate and sodium taurodeoxycholate, we show that the greatest extent of reaction is observed among a small population of nanotube species, with diameters between 0.88 and 0.92nm. The anomalous reaction of nanotubes in this diameter range implies that the surfactant is less effective at coating these species, resulting in a reduced surface coverage on the nanotube. Contrary to the other bile salts studied, sodium cholate enables high selectivity toward metallic species and small band-gap semiconductors, which is attributed to surfactant-diazonium coupling to form highly reactive diazoesters. We subsequently move on to examine excited-state electron transfer events between SWCNTs and fullerenes. This electron transfer system is distinct from the diazonium system since it does not result in the formation of a covalent bond between the donor and acceptor species. To study this interface, we synthesized a series of methanofullerene amphiphiles, including derivatives of C60 , C70, and C84, and investigated their electron transfer with SWCNT of specific chirality, generating a structure/reactivity relationship. In the cases of lipid-C61-PEG and lipid-C 71-PEG, which are predicted to similar surfactant surface coverages, band-gap dependent, incomplete quenching was observed across all semiconducting species, indicating that the driving force for electron transfer from SWCNT is small. This is further supported by a Marcus theory model, which predicts that the energy offsets between the SWCNT conduction bands and the fullerene LUMO levels are less than the exciton binding energy of the SWCNT in these two systems. In contrast, the lipid-C 85-PEG derivative shows complete quenching of all SWCNT species utilized in this work. This enhancement in quenching efficiency is consistent with the fact that the LUMO level of C85 methanofullerene is approximately 0.35eV lower than that of the smaller fullerene adducts, resulting in energy offsets which exceed the exciton binding energy. This result, combined with the fact that C8 5 has much higher photo-stability than C61 and C71, makes this larger fullerene adduct a promising candidate for SWCNT-based sensors and photovoltaics. Finally, we design and synthesize fullerene derivatives that self-assemble into onedimensional arrays. We find that a dendritic fullerene, which possesses a Boc-L-Ser-L-Ala-OMe dipeptide sequence at its apex, selectively forms S-oriented, helical, one-dimensional nanowires upon cooling from an isotropic state in cyclohexane. These nanowires possess diameters of 3.76 ± 0.52nm, and can be several microns in length. Control molecules, which do not possess the dipeptide sequence, only produce poorly formed aggregates under identical conditions, indicating that dipeptide-dipeptide interactions are integral to assembly. These nanorods open new opportunities in the chiral assembly of novel electron acceptor materials for optoelectronic and photovoltatic applications.by Andrew J. Hilmer.Ph.D

    The association between benzodiazepine use and sleep quality in residential aged care facilities: a cross-sectional study

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    BACKGROUND: Benzodiazepines are commonly prescribed in residential aged care facilities (RACFs) for their sedative and anxiolytic effects. The objective of this study was to investigate the association between benzodiazepine use and sleep quality in residents of RACFs. METHODS: A cross-sectional study involving 383 participants was conducted in six Australian RACFs. Night-time sleep quality, day-time drowsiness and day-time napping behavior were assessed using a validated questionnaire. Logistic regression was used to compute adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for the association between benzodiazepine use and sleep quality. Covariates included pain, dementia severity, depression, insomnia and other sedative use. RESULTS: Of the 383 residents (mean age 87.5 years, 77.5% female), 96(25.1%) used a benzodiazepine on a regular basis. Residents who used long-acting benzodiazepines on a regular basis had higher night-time sleep quality than non-users (AOR = 4.00, 95%CI 1.06 - 15.15). Residents who used short-acting benzodiazepines on a PRN only basis had longer daytime napping times than non-users (AOR = 1.77, 95%CI 1.01 - 3.08). No benzodiazepine category was associated with day-time drowsiness. CONCLUSIONS: The association between benzodiazepine use and sleep quality is dependent on the half-life and prescribing pattern of the benzodiazepine. Short-acting PRN benzodiazepines were associated with lower night time sleep quality and longer day-time napping compared to long-acting regular benzodiazepines. Longitudinal studies are needed to determine whether these findings reflect channeling of short-acting agents to residents at higher risk of sleep disorders.Lynna Chen, J. Simon Bell, Renuka Visvanathan, Sarah N. Hilmer, Tina Emery, Leonie Robson, Jessica M. Hughes and Edwin C. K. Ta

    Caregivers’ experiences of medication management advice for people living with dementia at discharge

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    Acknowledgments: StepUp for Dementia Research, which is funded by the Australian Government Department of Health and implemented by a dedicated team at the University of Sydney. Journal of Evaluation in Clinical Practice Funding : The project and DG was supported by the Australian National Health and Medical Research Council Dementia Leadership Fellowship.Peer reviewedPostprin

    The Nucleotide Exchange Factor Ric-8A is a Chaperone for the Conformationally Dynamic Nucleotide-Free State of G Alpha I1

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    Heterotrimeric G protein alpha subunits are activated upon exchange of GDP for GTP at the nucleotide binding site of G alpha, catalyzed by guanine nucleotide exchange factors (GEFs). In addition to transmembrane G protein-coupled receptors (GPCRs), which act on G protein heterotrimers, members of the family cytosolic proteins typified by mammalian Ric-8A are GEFs for Gi/q/12/13-class G alpha subunits. Ric-8A binds to G alpha.GDP, resulting in the release of GDP. The Ric-8A complex with nucleotide-free G alpha i1 is stable, but dissociates upon binding of GTP to G alpha i1. To gain insight into the mechanism of Ric-8A-catalyzed GDP release from G alpha i1, experiments were conducted to characterize the physical state of nucleotide-free G alpha i1 (hereafter referred to as G alpha i1[]) in solution, both as a monomeric species, and in the complex with Ric-8A. We found that Ric-8A-bound, nucleotide-free G alpha i1 is more accessible to trypsinolysis than G alpha i1.GDP, but less so than G alpha i1[] alone. The TROSY-HSQC spectrum of [N-15]G alpha i1[] bound to Ric-8A shows considerable loss of peak intensity relative to that of [N-15]G alpha i1.GDP. Hydrogen-deuterium exchange in G alpha i1[] bound to Ric-8A is 1.5-fold more extensive than in G alpha i1.GDP. Differential scanning calorimetry shows that both Ric-8A and G alpha i1.GDP undergo cooperative, irreversible unfolding transitions at 47 degrees and 52 degrees, respectively, while nucleotide-free G alpha i1 shows a broad, weak transition near 35 degrees. The unfolding transition for Ric-8A: G alpha i1[] is complex, with a broad transition that peaks at 50 degrees, suggesting that both Ric-8A and G alpha i1[] are stabilized within the complex, relative to their respective free states. The C-terminus of G alpha i1 is shown to be a critical binding element for Ric-8A, as is also the case for GPCRs, suggesting that the two types of GEF might promote nucleotide exchange by similar mechanisms, by acting as chaperones for the unstable and dynamic nucleotide-free state of G alpha
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