16,026 research outputs found
Topological first-order solitons in a gauged model with the Maxwell-Chern-Simons action
We verify the existence of radially symmetric first-order solitons in a
gauged scenario in which the dynamics of the Abelian gauge field is
controlled by the Maxwell-Chern-Simons action. We implement the standard
Bogomol'nyi-Prasad-Sommerfield (BPS) formalism, from which we obtain a
well-defined lower bound for the corresponding energy (i.e. the Bogomol'nyi
bound) and the first-order equations saturating it. We solve these first-order
equations numerically by means of the finite-difference scheme, therefore
obtaining regular solutions of the effective model, their energy being
quantized according the winding number rotulating the final configurations, as
expected. We depict the numerical solutions, whilst commenting on the main
properties they engender.Comment: 8 pages, 9 figure
Forced-flow once-through boilers
A compilation and review of NASA-sponsored research on boilers for use in spacecraft electrical power generation systems is presented. Emphasis is on the heat-transfer and fluid-flow problems. In addition to space applications, much of the boiler technology is applicable to terrestrial and marine uses such as vehicular power, electrical power generation, vapor generation, and heating and cooling. Related research areas are discussed such as condensation, cavitation, line and boiler dynamics, the SNAP-8 project (Mercury-Rankine cycle), and conventional terrestrial boilers (either supercritical or gravity-assisted liquid-vapor separation types). The research effort was directed at developing the technology for once-through compact boilers with high heat fluxes to generate dry vapor stably, without utilizing gravity for phase separations. A background section that discusses, tutorially, the complex aspects of the boiling process is presented. Discussions of tests on alkali metals are interspersed with those on water and other fluids on a phenomenological basis
Cross-Border Investment, Conflict of Laws, and the Privatization of Securities Law
The rapid acceleration of transnational investing is occurring in an environment in which emerging markets, and foreign interest in these markets, are exploding. The issues involved with cross-border investment, conflict of laws and the privatization of securities law are examined
Photoluminescence from nanocrystalline graphite monofluoride
We synthesize and study the structural and optical properties of
nanocrystalline graphene monofluoride and graphite monofluoride, which are
carbon-based wide bandgap materials. Using laser excitations 2.41 - 5.08 eV, we
identify six emission modes of graphite monofluoride, spanning the visible
spectrum from red to violet. The energy and linewidth of the modes point to
defect-induced midgap states as the source of the photoemission. We discuss
possible candidates. Our findings open the window to electro-optical
applications of graphene fluoride.Comment: 11 pages including supporting information, 2 figure
Mechanical transmission of rotational motion between molecular-scale gears
Manipulating and coupling molecule gears is the first step towards realizing
molecular-scale mechanical machines. Here, we theoretically investigate the
behavior of such gears using molecular dynamics simulations. Within a nearly
rigid-body approximation we reduce the dynamics of the gears to the rotational
motion around the orientation vector. This allows us to study their behavior
based on a few collective variables. Specifically, for a single hexa
(4-tert-butylphenyl) benzene molecule we show that the rotational-angle
dynamics corresponds to the one of a Brownian rotor. For two such coupled
gears, we extract the effective interaction potential and find that it is
strongly dependent on the center of mass distance. Finally, we study the
collective motion of a train of gears. We demonstrate the existence of three
different regimes depending on the magnitude of the driving-torque of the first
gear: underdriving, driving and overdriving, which correspond, respectively, to
no collective rotation, collective rotation and only single gear rotation. This
behavior can be understood in terms of a simplified interaction potential
Determining Pathways and Connections Between Access to Water and High School Noncompletion Rates for Communities Along the U.S.–Mexico Border
Lack of access to potable water through a conveyance system impacts all aspects of modern life. Many colonias, communities in the Southwestern United States along the U.S.–Mexico border, continue to lack access to piped and treated water. This article discusses a model for the pathway from lack of access to water to lack of high school completion, including intermediary conditions impacting wellness, health, and quality of life for community members. A facilitated discussion with five environmental and public health experts who frequently work in the colonias of El Paso County, Texas (border communities that resemble the developing world), established common themes found in these communities. This process mapped the pathway from lack of access to water to noncompletion of high school for residents of the colonias. Further analysis of the pathway led to a model that describes these conditions in terms of built, cultural, human, and political capitals using the capital community framework (Emery & Flora, 2008). The resulting model determines local community investments for advancing positive effects on the beginning, intermediary, and end conditions in the pathway, which have the capacity to positively impact education outcomes. The resulting model can be used to inform policy makers in making investment decisions for developing communities throughout the world including those that face devastation and are in the process of rebuilding sustainable infrastructure with limited financial capital
Are low-frequency songs sexually selected, and do they lose their potency in male–female interactions under noisy conditions?
ABSTRACT: We agree with Halfwerk et al. on the importance of including the receivers when studying the impact of anthropogenic noise. However, we find the conclusion that the use of lowfrequency song is sexually selected in great tits and that noisy conditions affect male–female communication premature for several reasons
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