13,275 research outputs found
Effect of psychotropic drugs on gastric ulcers induced by immobilization: Increased protective effect of amitriptyline caused by chlordiazepoxide
Amitriptyline, but not chlordiazepoxide, protects rats from the occurrence of gastric erosions and ulcers following immobilization. When, however, chlordiazepoxide is given together with amitriptyline the protective effect of the latter is markedly increased
Control of electron spin and orbital resonance in quantum dots through spin-orbit interactions
Influence of resonant oscillating electromagnetic field on a single electron
in coupled lateral quantum dots in the presence of phonon-induced relaxation
and decoherence is investigated. Using symmetry arguments it is shown that spin
and orbital resonance can be efficiently controlled by spin-orbit interactions.
The control is possible due to the strong sensitivity of Rabi frequency to the
dot configuration (orientation of the dot and a static magnetic field) as a
result of the anisotropy of the spin-orbit interactions. The so called easy
passage configuration is shown to be particularly suitable for magnetic
manipulation of spin qubits, ensuring long spin relaxation time and protecting
the spin qubit from electric field disturbances accompanying on-chip
manipulations.Comment: 11 pages, 5 figures; v2: introduction and conclusions broadened,
moderate structure and content change
Golden Ratio Prediction for Solar Neutrino Mixing
It has recently been speculated that the solar neutrino mixing angle is
connected to the golden ratio phi. Two such proposals have been made, cot
theta_{12} = phi and cos theta_{12} = phi/2. We compare these Ansatze and
discuss a model leading to cos theta_{12} = phi/2 based on the dihedral group
D_{10}. This symmetry is a natural candidate because the angle in the
expression cos theta_{12} = phi/2 is simply pi/5, or 36 degrees. This is the
exterior angle of a decagon and D_{10} is its rotational symmetry group. We
also estimate radiative corrections to the golden ratio predictions.Comment: 15 pages, 1 figure. Matches published versio
Stem clutch for motor driven valve
Development of mechanical device to reduce possibility of damage to motor driven needle valve is discussed. Mechanical clutch is employed to allow slippage when needle valve reaches limit of travel. Operation of system for various conditions is described
An HFB scheme in natural orbitals
We present a formulation of the Hartree-Fock-Bogoliubov (HFB) equations which
solves the problem directly in the basis of natural orbitals. This provides a
very efficient scheme which is particularly suited for large scale calculations
on coordinate-space grids.Comment: 5 pages RevTeX, (Postscript-file also available at
http://www.th.physik.uni-frankfurt.de/~bender/nucl_struct_publications.html
or at ftp://th.physik.uni-frankfurt.de/pub/bender ), accepted for publication
in Z. Phys.
Low-velocity collisions of centimeter-sized dust aggregates
Collisions between centimeter- to decimeter-sized dusty bodies are important
to understand the mechanisms leading to the formation of planetesimals. We thus
performed laboratory experiments to study the collisional behavior of dust
aggregates in this size range at velocities below and around the fragmentation
threshold. We developed two independent experimental setups with the same goal
to study the effects of bouncing, fragmentation, and mass transfer in free
particle-particle collisions. The first setup is an evacuated drop tower with a
free-fall height of 1.5 m, providing us with 0.56 s of microgravity time so
that we observed collisions with velocities between 8 mm/s and 2 m/s. The
second setup is designed to study the effect of partial fragmentation (when
only one of the two aggregates is destroyed) and mass transfer in more detail.
It allows for the measurement of the accretion efficiency as the samples are
safely recovered after the encounter. Our results are that for very low
velocities we found bouncing as could be expected while the fragmentation
velocity of 20 cm/s was significantly lower than expected. We present the
critical energy for disruptive collisions Q*, which showed up to be at least
two orders of magnitude lower than previous experiments in the literature. In
the wide range between bouncing and disruptive collisions, only one of the
samples fragmented in the encounter while the other gained mass. The accretion
efficiency in the order of a few percent of the particle's mass is depending on
the impact velocity and the sample porosity. Our results will have consequences
for dust evolution models in protoplanetary disks as well as for the strength
of large, porous planetesimal bodies
Compaction, cratering and collision frequency on chondritic parent objects
Calculamos el grado de compactación de un asteroide de 100 km de radio debido a un impacto con un asteroide pequeño para velocidades de impacto entre 3 y 5 km s−1. Calculamos el radio del cráter producto del impacto. Obtenemos además el número de impactos sobre el asteroide de 100 km de radio con toda la distribución de asteroides pequeños durante la edad del Sistema Solar.We calculate the compaction of an asteroid with radius 100 km due to an impact with a small asteroid for impact velocities between 3 and 5 km s−1. The crater formed on the target surface as a result of such an impact is calculated. The number of impacts on the target with the distribution of small asteroids during the age of the Solar System is computed.Fil: Parisi, Mirta Gabriela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones CientÃficas. Instituto Argentino de RadioastronomÃa. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Instituto Argentino de RadioastronomÃa; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofÃsicas; ArgentinaFil: Beitz, E.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Blum, J.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaReunión anual de la Asociación Argentina de AstronomÃaLa PlataArgentinaUniversidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofÃsicasUniversidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofÃsicas. Instituto de AstrofÃsica La Plat
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