8,786 research outputs found
Semirelativistic stability of N-boson systems bound by 1/r pair potentials
We analyze a system of self-gravitating identical bosons by means of a
semirelativistic Hamiltonian comprising the relativistic kinetic energies of
the involved particles and added (instantaneous) Newtonian gravitational pair
potentials. With the help of an improved lower bound to the bottom of the
spectrum of this Hamiltonian, we are able to enlarge the known region for
relativistic stability for such boson systems against gravitational collapse
and to sharpen the predictions for their maximum stable mass.Comment: 11 pages, considerably enlarged introduction and motivation,
remainder of the paper unchange
The Evolution of Life History Traits and Their Thermal Plasticity in Daphnia
Few studies have explored the relative strength of ecogeographic versus lineage-specific effects on a global scale, particularly for poikilotherms, those organisms whose internal temperature varies with their environment. Here, we compile a global dataset of life history traits in Daphnia, at the species-and population-level, and use those data to parse the relative influences of lineage-specific effects and climate. We also compare the thermal response (plasticity) of life history traits and their dependence on climate, temperature, precipitation, and latitude. We found that the mode of evolution for life history traits varies but that the thermal response of life history traits most often follows a random walk model of evolution. We conclude that life history trait evolution in Daphnia is not strongly species-specific but is ecogeographically distinct, suggesting that life history evolution should be understood at the population level for Daphnia and possibly for other poikilotherms
Key physicochemical characteristics governing organic micropollutant adsorption and transport in ion-exchange membranes during reverse electrodialysis
The co-generation of electricity and electrodialysis of seawater in a hybrid system is a promising approach to overcome water scarcity. Reverse electrodialysis harvests energy from the salinity gradient, where seawater is used as a high salinity stream while secondary treated wastewater can be used as a sustainable low salinity stream. Treated wastewater contains organic micropollutants, which can be transported to the seawater stream. The current research establishes a connection between adsorption and transport of organic micropollutants in ion exchange membranes, using a cross-flow stack in adsorption and zero-current experiments. To mimic the composition of treated wastewater, a mixture of nineteen organic micropollutants of varied physicochemical characteristics (e.g. size, charge, polarity, hydrogen donor/acceptor count, hydrophobicity) at environmentally relevant concentrations was used. Depending on the charge, micropollutants develop different types of mechanisms responsible for short-distance interactions with ion-exchange membranes, which has a direct influence in their transport behavior. This study provides a rational basis for the optimization/design of next-generation ion-exchange membranes, in which the permeability toward organic micropollutants should be also included. This investigation highly contributes to understanding the potential hazard posed by organic micropollutants in reverse electrodialysis in seawater desalination systems, where treated wastewater is used as a low salinity stream
An infinite family of superintegrable Hamiltonians with reflection in the plane
We introduce a new infinite class of superintegrable quantum systems in the
plane. Their Hamiltonians involve reflection operators. The associated
Schr\"odinger equations admit separation of variables in polar coordinates and
are exactly solvable. The angular part of the wave function is expressed in
terms of little -1 Jacobi polynomials. The spectra exhibit "accidental"
degeneracies. The superintegrability of the model is proved using the
recurrence relation approach. The (higher-order) constants of motion are
constructed and the structure equations of the symmetry algebra obtained.Comment: 19 page
Deliverable 1.1 Identification of potential psychological factors influencing the passenger and road user acceptance of CAV
Magnetization and magnetoresistance in insulating phases of SrFeO3-d
We report the synthesis and properties of two new insulating phases of
SrFeO3-d with introduction of oxygen deficiencies in metallic SrFeO3 ; one with
0.15 < d < 0.19 (sample A)and the other above d = 0.19 (sample B). Sample A
shows large negative magnetoresistance around the charged ordering (CO)
temperature with magnetic anomalies seen in the temperature dependent
resistivity,magnetization and M-H hysteresis loops. Sample B shows a smooth
insulating behavior with no thermal hysteresis in the resistivity and with a
small positive magnetoresistance. cac and cdc show multiple features associated
with a frustrated magnetic order (helical) due to competing ferro- and
antiferromagnetic interactions. The competing effects of ferro- and
antiferromagnetic phases extend up to T ~ 230 K revealing a new high
temperature scale in this system. These observations are discussed in the
context of magnetic interactions associated with the varying Fe4+/Fe3+ ratio.Comment: 11 pages, 4 figure
Deliverable 1.1 Identification of potential psychological factors influencing the passenger and road user acceptance of CAV
Deliverable 1.1 Identification of potential psychological factors influencing the passenger and road user acceptance of CAV
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