39,214 research outputs found
Prospects of developing cage and pen culture in Sudan
This paper describes the prospects of cage and pen culture in Sudan and recommends that a project for developing pen and cage culture techniques be started for marine and freshwater aquaculture
Geodesic properties in terms of multipole moments in scalar-tensor theories of gravity
The formalism for describing a metric and the corresponding scalar in terms
of multipole moments has recently been developed for scalar-tensor theories. We
take advantage of this formalism in order to obtain expressions for the
observables that characterise geodesics in terms of the moments. These
expressions provide some insight into how the structure of a scalarized compact
object affects observables. They can also be used to understand how deviations
from general relativity are imprinted on the observables.Comment: 16 page
Friction due to inhomogeneous driving of coupled spins in a quantum heat engine
We consider two spin-1/2 particles with isotropic Heisenberg interaction, as
the working substance of a quantum heat engine. We observe a frictional effect
on the adiabatic branches of the heat cycle, which arises due to an
inhomogeneous driving at a finite rate of the external magnetic field. The
frictional effect is characterized by entropy production in the system and
reduction in the work extracted. Corresponding to a sudden and a very slow
driving, we find expressions for the lower and upper bounds of work that can be
extracted on the adiabatic branches. These bounds are also confirmed with
numerical simulations of the corresponding Liouville-von Neumann equation.Comment: 5 pages, 2 figure
Surface micromachined membranes for tunnel transducers
We have developed low-temperature surface micromachining procedures for the fabrication of suspended SiO2/Si3N4 membranes. This fabrication method was integrated with electron beam lithography, anisotropic ion etching, and electroplating to construct electrostatically deflectable tunnel transducers. We show the structures and some preliminary measurements on the performance of these monolithic devices
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