4,410 research outputs found
Electronic interactions and thermal disorder in mlecular crystals containing cofacial pentacene units.
No full textWe computed the intermolecular electronic coupling and the band structure of three pentacene derivatives
that stack cofacially in one or two dimensions. We rationalize the results building a map of the coupling
between HOMOs and LUMOs of isolated pentacene molecules as a function of the relative molecular
orientation and finding the position on such map of the actual molecular pairs. The apparently chaotic
dependence of the intermolecular coupling from the crystal structure is explained, and directions for the
design of materials with improved electric transport properties are given. We run molecular dynamics
simulations to explore the variation of the intermolecular coupling due to the thermal motions. It is
shown that, even in the crystal phase, the limited conformational space explored at room temperature is
large enough to produce consistent variation in the intermolecular coupling. The consequences of this
finding on the practicability of the transport properties of organic materials are analyzed
Recommended from our members
Preliminary Geologic Map of the North Half of the Union Pass Quadrangle, Mohave County, Arizona
No full textPreliminary Geologic Map of the North Half of the Union Pass Quadrangle, Mohave County, Arizona. Includes one map sheet with cross section at 1:24,000 map scale.On 1/17/2014, F.L. Hillemeyer's name was removed from the author list per his request. (The request was forwarded to AZGS by J.E. Faulds.)Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]
Building and Defining Behavioral Economics
No full textContains fulltext :
95156.pdf (Publisher’s version ) (Closed access)George Loewenstein, a prominent behavioral economist, recalls thatIn 1994, when Thaler, Camerer, Rabin, Prelec and I spent the year at the Center for Advanced Study in the Behavioral Sciences, we had a meeting to make a kind of final decision about what to call what we were doing. Remarkably, at that time, the name behavioral economics was not yet well established. I actually advocated “psychological economics,” and Thaler was strong on behavioral economics. I'm kind of glad that he prevailed; I think it's a better, catchier, label, although it creates confusion due to association with Behaviorism. (G. Loewenstein, personal email to author, June 16, 2008
The IPHAS catalogue of H alpha emission-line sources in the northern Galactic plane
No full textWe present a catalogue of point-source H alpha emission-line objects selected from the INT/WFC Photometric Ha Survey (IPHAS) of the northern Galactic plane. The catalogue covers the magnitude range 13 <= r' <= 19.5 and includes Northern hemisphere sources in the Galactic latitude range -5 degrees < b < 5 degrees. It is derived from similar to 1500 deg(2) worth of imaging data, which represents 80 per cent of the final IPHAS survey area. The electronic version of the catalogue will be updated once the full survey data become available. In total, the present catalogue contains 4853 point sources that exhibit strong photometric evidence for Ha emission. We have so far analysed spectra for similar to 300 of these sources, confirming more than 95 per cent of them as genuine emission-line stars. A wide range of stellar populations are represented in the catalogue, including early-type emission-line stars, active late-type stars, interacting binaries, young stellar objects and compact nebulae.
The spatial distribution of catalogue objects shows overdensities near sites of recent or current star formation, as well as possible evidence for the warp of the Galactic plane. Photometrically, the incidence of Ha emission is bimodally distributed in (r' - i'). The blue peak is made up mostly of early-type emission-line stars, whereas the red peak may signal an increasing contribution from other objects, such as young/active low-mass stars. We have cross-matched our H alpha-excess catalogue against the emission-line star catalogue of Kohoutek & Wehmeyer, as well as against sources in SIMBAD. We find that fewer than 10 per cent of our sources can be matched to known objects of any type. Thus IPHAS is uncovering an order of magnitude more faint (r' > 13) emission-line objects than were previously known in the Milky Way
Lipophilic balance – a new design principle for transmembrane anion carriers
No full textDespite extensive interest in transmembrane anion carriers (anionophores), the factors that govern activity are still only partly understood. Herein we report a study which identifies a new principle for anionophore design, that of “lipophilic balance”. A series of simple thioureas with identical molecular formulae has been prepared and assayed for chloride/nitrate transport activity in synthetic vesicles. The molecules differ only in the positioning of the phenylthiourea binding unit within an 11-carbon linear chain. They are shown to possess very similar lipophilicities and anion affinities, while a test for leaching establishes that they locate almost exclusively in the vesicle membranes. Notwithstanding their close similarities, activities across the series show >5-fold variation, peaking when the phenylthiourea group is centrally located. The results suggest that transport is favoured by a balanced array of lipophilic substituents, possibly because this arrangement facilitates transfer of the complexed anion into the apolar membrane interio
Testing protoplanetary disc dispersal with radio emission
No full textWe consider continuum free–free radio emission from the upper atmosphere of protoplanetary discs as a probe of the ionized luminosity impinging upon the disc. Making use of previously computed hydrodynamic models of disc photoevaporation within the framework of extreme-ultraviolet (EUV) and X-ray irradiation, we use radiative transfer post-processing techniques to predict the expected free–free emission from protoplanetary discs. In general, the free–free luminosity scales roughly linearly with ionizing luminosity in both EUV- and X-ray-driven scenarios, where the emission dominates over the dust tail of the disc and is partial optically thin at cm wavelengths. We perform a test observation of GM Aur at 14–18?GHz and detect an excess of radio emission above the dust tail to a very high level of confidence. The observed flux density and spectral index are consistent with free–free emission from the ionized disc in either the EUV- or the X-ray-driven scenario. Finally, we suggest a possible route to testing the EUV- and X-ray-driven dispersal model of protoplanetary discs, by combining observed free–free flux densities with measurements of mass-accretion rates. On the point of disc dispersal one would expect to find an M?2? scaling with free–free flux in the case of EUV-driven disc dispersal or an ?* scaling in the case of X-ray-driven disc dispersa
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Pinchi Lake Mercury Belt, British Columbia:
No full textby J.E. Armstrong.Paper (Geological Survey of Canada) ; 42-11
Wetzel, James Anthony (Death, 1902-06-26)
No full textAddress: 4720 Eastern AvenueAge at death: 10 months 14 days419/Pg.65/1902/M W S/City/Dr. J.E. Townsley/Mundell & Yungbluth/CalvaryOriginal record filed in drawer labeled 'WESTEN-WHITCON'
Recommended from our members
NBC News Scripts
No full textScript from the WBAP-TV/NBC station in Fort Worth, Texas, relating a news story about Peter Anthony Derks. Judge J.E. "Dutch" Winters sentenced Derks to 30 years in prison for raping a woman
- …
