3,001 research outputs found
Roger Parsons—Olin Palladium Award Medalist
The Olin Palladium Medal of this Society has such a distinguished set of former awardees that I suspect the person who has been asked to introduce each of the medal winners has probably felt as superfluous as I do today.
Roger Parsons has played so prominent a role in the development of fundamental electrochemistry in the last thirty years that his name and his ideas constantly pop up in discussions among electrochemists in Moscow and Buenos Aires, Delhi and Paris, College Station and Pasadena
Selfish Dark Matter
We present a mechanism where a particle asymmetry in one sector is used to
generate an asymmetry in another sector. The two sectors are not coupled
through particle number violating interactions and are not required to be in
thermal contact with each other. When this mechanism is applied to baryogenesis
in asymmetric dark matter models, we find that the dark matter particles can be
extremely light, e.g. much lighter than an eV, and that in some cases there is
no need to annihilate away the symmetric component of dark matter. We discuss a
concrete realization of the mechanism with signals in direct detection, at the
LHC, at -factories or future beam dump experiments.Comment: 18+5 pages, 2 figures; Journal version: Added references, small
changes to the free-streaming length estimate
Brownian molecular motors driven by rotation-translation coupling
We investigated three models of Brownian motors which convert rotational
diffusion into directed translational motion by switching on and off a
potential. In the first model a spatially asymmetric potential generates
directed translational motion by rectifying rotational diffusion. It behaves
much like a conventional flashing ratchet. The second model utilizes both
rotational diffusion and drift to generate translational motion without spatial
asymmetry in the potential. This second model can be driven by a combination of
a Brownian motor mechanism (diffusion driven) or by powerstroke (drift driven)
depending on the chosen parameters. In the third model, elements of both the
Brownian motor and powerstroke mechanisms are combined by switching between
three distinct states. Relevance of the model to biological motor proteins is
discussed.Comment: 11 pages, 8 figure
Design of an exhaust mixer nozzle for the Avco-Lycoming Quiet Clean General Aviation Turbofan (QCGAT)
This report describes the design configuration and method used to design the forced engine exhaust to bypass air mixing system for Lycoming's QCGAT engine. This mixer is an integral part of the total engine and nacelle system and was configured to reduce the propulsion system noise and fuel consumption levels
Environmental risks and challenges associated with neonicotinoid insecticides
Neonicotinoid use has increased rapidly in recent years, with a global shift toward insecticide applications as seed coatings rather than aerial spraying. While the use of seed coatings can lessen the amount of overspray and drift, the near universal and prophylactic use of neonicotinoid seed coatings on major agricultural crops has led to widespread detections in the environment (pollen, soil, water, honey). Pollinators and aquatic insects appear to be especially susceptible to the effects of neonicotinoids with current research suggesting that chronic sublethal effects are more prevalent than acute toxicity. Meanwhile, evidence of clear and consistent yield benefits from the use of neonicotinoids remains elusive for most crops. Future decisions on neonicotinoid use will benefit from weighing crop yield benefits versus environmental impacts to nontarget organisms and considering whether there are more environmentally benign alternatives
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SMM behaviour and magnetocaloric effect in heterometallic 3d-4f coordination clusters with high azide : metal ratios
We present the synthesis and characterization of heterometallic compounds with a very large azide to metal ratio and fascinating magnetic properties
Inferring Mobility of Care Travel Behavior From Transit Origin-Destination Data
There are substantial differences in travel behavior by gender on public
transit. Studies have concluded that these differences are largely attributable
to household responsibilities typically falling disproportionately on women,
leading to women being more likely to utilize transit for purposes referred to
by the umbrella concept of "mobility of care". In contrast to past studies that
have quantified the impact of gender using survey and qualitative data, we
propose a novel data-driven workflow utilizing a combination of previously
developed origin, destination, and transfer inference (ODX) based on individual
transit fare card transactions, name-based gender inference, and geospatial
analysis as a framework to identify mobility of care trip making. We apply this
framework to data from the Washington Metropolitan Area Transit Authority
(WMATA). Analyzing data from millions of journeys conducted in the first
quarter of 2019, the results of this study show that our proposed workflow can
identify mobility of care travel behavior, detecting times and places of
interest where the share of women travelers in an equally-sampled subset (on
basis of inferred gender) of transit users is 10% - 15% higher than that of
men. The workflow presented in this study provides a blueprint for combining
transit origin-destination data, inferred customer demographics, and geospatial
analyses enabling public transit agencies to assess, at the fare card level,
the gendered impacts of different policy and operational decisions.Comment: Updated reference formatting and discussion point
A Formalism for Predicting Ultrasonic Properties of Alloys in a Semi-Solid State
When an alloy is in a semi-solid state, it is a heterogeneous material similar to a suspension where the dominant phase can be taken as the matrix and the minor phase as the inclusion. Typically, first-order scattering theories are considered adequate for describing the wave mechanics of a suspensions when the inclusion concentration levels are low. However, as the concentration is increased, higher ordered scattering theories become necessary. Due to the mathematical complexities of these methods, many researchers have pursued effective media approaches[1]. It should be noted however, that neither scattering heories nor effective media theories account for dynamic changes in the material state.</p
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