1,767 research outputs found
Avalanche noise characteristics of thin GaAs structures with distributed carrier generation
It is known that both pure electron and pure hole injection into thin GaAs multiplication regions gives rise to avalanche multiplication with noise lower than predicted by the local noise model. In this paper, it is shown that the noise from multiplication initiated by carriers generated throughout a 0.1 μm avalanche region is also lower than predicted by the local model but higher than that obtained with pure injection of either carrier type. This behavior is due to the effects of nonlocal ionization brought about by the dead space; the minimum distance a carrier has to travel in the electric field to initiate an ionization even
Transport of Surface States in the Bulk Quantum Hall Effect
The two-dimensional surface of a coupled multilayer integer quantum Hall
system consists of an anisotropic chiral metal. This unusual metal is
characterized by ballistic motion transverse and diffusive motion parallel
(\hat{z}) to the magnetic field. Employing a network model, we calculate
numerically the phase coherent two-terminal z-axis conductance and its
mesoscopic fluctuations. Quasi-1d localization effects are evident in the limit
of many layers. We consider the role of inelastic de-phasing effects in
modifying the transport of the chiral surface sheath, discussing their
importance in the recent experiments of Druist et al.Comment: 9 pages LaTex, 9 postscript figures included using eps
The mixed problem in L^p for some two-dimensional Lipschitz domains
We consider the mixed problem for the Laplace operator in a class of
Lipschitz graph domains in two dimensions with Lipschitz constant at most 1.
The boundary of the domain is decomposed into two disjoint sets D and N. We
suppose the Dirichlet data, f_D has one derivative in L^p(D) of the boundary
and the Neumann data is in L^p(N). We find conditions on the domain and the
sets D and N so that there is a p_0>1 so that for p in the interval (1,p_0), we
may find a unique solution to the mixed problem and the gradient of the
solution lies in L^p
B_c meson rare decays in the light-cone quark model
We investigate the rare decays
and in the framework of the
light-cone quark model (LCQM). The transition form factors are calculated in
the space-like region and then analytically continued to the time-like region
via exponential parametrization. The branching ratios and longitudinal lepton
polarization asymmetries (LPAs) for the two decays are given and compared with
each other. The results are helpful to investigating the structure of
meson and to testing the unitarity of CKM quark mixing matrix. All these
results can be tested in the future experiments at the LHC.Comment: 9 pages, 11 figures, version accepted for publication in EPJ
Поліфонічні прийоми в духовних творах Ігоря Мацієвського
У пропонованій статті розглядаються поліфонічні прийоми в деяких зразках духовної вокально-хорової та інструментальної музики сучасного представника української діаспори в Петербурзі, провідного вченого-етноінструментознавця й композитора Ігоря Мацієвського. Знання глибинних законів етномузики слов’янських народів дозволило йому стати не лише фундатором української й російської етноорганології, але й автором оригінальних композицій, у мові яких органічно поєднуються академічність, авангардизм, елементи гуцульської, лемківської, підляської, білоруської, польської та російської народної музики.В статье рассматриваются полифонические приёмы в некоторых образцах духовной вокально-хоровой и инструментальной музыки современного представителя украинськой диаспоры в Санкт-Петербурге, выдающегося учёного и композитора Игоря Мациевского.The polyphonic methods in some examples of the spiritual vocal-choral and instrumental music of Igor Matsiyevsky, a modern representative of the Ukrainian Diaspora in St. Petersburg, are studied in the article. The profound knowledge of the very nature of Slavonic ethnical music helped him to become not only a founder of the Ukrainian and Russian ethnoorganology, but also an author of the genuine compositions, in language of which academicism, avant-gardism and the elements of Guzulska, Lemkivska, Pidlyaska, Belorussian, Polish and Russian folk music are organically combined
Spin dynamics of a trapped spin-1 Bose Gas above the Bose-Einstein transition temperature
We study collective spin oscillations in a spin-1 Bose gas above the
Bose-Einstein transition temperature. Starting from the Heisenberg equation of
motion, we derive a kinetic equation describing the dynamics of a thermal gas
with the spin-1 degree of freedom. Applying the moment method to the kinetic
equation, we study spin-wave collective modes with dipole symmetry. The dipole
modes in the spin-1 system are found to be classified into the three type of
modes. The frequency and damping rate are obtained as functions of the peak
density. The damping rate is characterized by three relaxation times associated
with collisions.Comment: 19 pages, 5 figur
Gravitation and inertia; a rearrangement of vacuum in gravity
We address the gravitation and inertia in the framework of 'general gauge
principle', which accounts for 'gravitation gauge group' generated by hidden
local internal symmetry implemented on the flat space. We connect this group to
nonlinear realization of the Lie group of 'distortion' of local internal
properties of six-dimensional flat space, which is assumed as a toy model
underlying four-dimensional Minkowski space. The agreement between proposed
gravitational theory and available observational verifications is satisfactory.
We construct relativistic field theory of inertia and derive the relativistic
law of inertia. This theory furnishes justification for introduction of the
Principle of Equivalence. We address the rearrangement of vacuum state in
gravity resulting from these ideas.Comment: 17 pages, no figures, revtex4, Accepted for publication in Astrophys.
Space Sc
The fermi arc and fermi pocket in cuprates in a short-range diagonal stripe phase
In this paper we studied the fermi arc and the fermi pocket in cuprates in a
short-range diagonal stripe phase with wave vectors , which
reproduce with a high accuracy the positions and sizes of the fermi arc and
fermi pocket and the superstructure in cuprates observed by Meng et
al\cite{Meng}. The low-energy spectral function indicates that the fermi pocket
results from the main band and the shadow band at the fermi energy. Above the
fermi energy the shadow band gradually departs away from the main band, leaving
a fermi arc. Thus we conclude that the fermi arc and fermi pocket can be fully
attributed to the stripe phase but has nothing to do with pairing.
Incorporating a d-wave pairing potential in the stripe phase the spectral
weight in the antinodal region is removed, leaving a clean fermi pocket in the
nodal region.Comment: 5 pages, 6 figure
The effects of the bacterial interaction with visible-light responsive titania photocatalyst on the bactericidal performance
Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2
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