877 research outputs found
Leafhopper feeding behaviour on three grapevine cultivars with different susceptibilities to Flavescence dorée
Scaphoideus titanus fitness on grapevine varieties with different susceptibility to Flavescence dorée phytoplasma
Josephson effect in MgB_2 break junctions
We present the first observation of the DC and AC Josephson effect in MgB_2
break junctions. The junctions, obtained at 4.2 K in high-quality, high-density
polycrystalline metallic MgB_2 samples, show a non-hysteretic DC Josephson
effect. By irradiating the junctions with microwaves we observe clear Shapiro
steps spaced by the ideal value. The temperature dependence of the
DC Josephson current and the dependence of the height of the steps on the
microwave power are obtained. These results are a direct prove for the
existence of pairs with charge 2e in this new metallic superconductor and give
evidence of the superconductor-normal metal-superconductor weak link character
of these junctions.Comment: 4 RevTEX pages, 4 eps figure
GHItaly19: Research Perspectives on Game Human Interaction
This is a short introduction to the papers presented at the 3rd Workshop on Games-Human Interaction - GHItaly19, that was held in connection with CHItaly 2019. This series of workshops focuses on the multifaceted issues related to the design and development of human-game interfaces. This entails multidisciplinary competences and skills, and the final quality of the User eXperience depends on how consistently and smartly they are exploited. As a matter of fact, users\u2019 engagement and satisfaction rely on the wise design and skilled evaluation of the produced (multidimensional) artifacts. This gains even more critical importance since the application of video games has long overcome the borders of amusement, to spur new possibilities for, e.g., continuous healthcare and education
Detection of the Vortex Dynamic Regimes in MgB2 by Third Harmonic AC Susceptibility Measurements
In a type-II superconductor the generation of higher harmonics in the
magnetic response to an alternating magnetic field is a consequence of the
non-linearity in the I-V relationship. The shape of the current-voltage (I-V)
curve is determined by the current dependence of the thermal activation energy
U(J) and is thus related to the dynamical regimes governing the vortex motion.
In order to investigate the vortex dynamics in MgB2 bulk superconductors we
have studied the fundamental (chi1) and third (chi3) harmonics of the ac
magnetic susceptibility. Measurements have been performed as a function of the
temperature and the dc magnetic field, up to 9 T, for various frequencies and
amplitudes of the ac field. We show that the analysis of the behaviour in
frequency of chi3(T) and chi3(B) curves can provide clear information about the
non-linearity in different regions of the I-V characteristic. By comparing the
experimental curves with numerical simulations of the non-linear diffusion
equation for the magnetic field we are able to resolve the crossover between a
dissipative regime governed by flux creep and one dominated by flux flow
phenomena.Comment: to be published in "Horizons in Superconductivity Research" (Nova
Science Publishers, Inc., NY, 2003
GHItaly19: Research Perspectives on Game Human Interaction
This is a short introduction to the papers presented at the 3rd Workshop on Games-Human Interaction - GHItaly19, that was held in connection with CHItaly 2019. This series of workshops focuses on the multifaceted issues related to the design and development of human-game interfaces. This entails multidisciplinary competences and skills, and the final quality of the User eXperience depends on how consistently and smartly they are exploited. As a matter of fact, usersâ engagement and satisfaction rely on the wise design and skilled evaluation of the produced (multidimensional) artifacts. This gains even more critical importance since the application of video games has long overcome the borders of amusement, to spur new possibilities for, e.g., continuous healthcare and education
On a semiclassical formula for non-diagonal matrix elements
Let be a Schr\"odinger operator on the real
line, be a bounded observable depending only on the coordinate and
be a fixed integer. Suppose that an energy level intersects the potential
in exactly two turning points and lies below
. We consider the semiclassical limit
, and where is the th
eigen-energy of . An asymptotic formula for , the
non-diagonal matrix elements of in the eigenbasis of , has
been known in the theoretical physics for a long time. Here it is proved in a
mathematically rigorous manner.Comment: LaTeX2
Dust remobilization in fusion plasmas under steady state conditions
The first combined experimental and theoretical studies of dust
remobilization by plasma forces are reported. The main theoretical aspects of
remobilization in fusion devices under steady state conditions are analyzed. In
particular, the dominant role of adhesive forces is highlighted and generic
remobilization conditions - direct lift-up, sliding, rolling - are formulated.
A novel experimental technique is proposed, based on controlled adhesion of
dust grains on tungsten samples combined with detailed mapping of the dust
deposition profile prior and post plasma exposure. Proof-of-principle
experiments in the TEXTOR tokamak and the EXTRAP-T2R reversed-field pinch are
presented. The versatile environment of the linear device Pilot-PSI allowed for
experiments with different magnetic field topologies and varying plasma
conditions that were complemented with camera observations.Comment: 16 pages, 11 figures, 3 table
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