13,323 research outputs found
Constructions of biangular tight frames and their relationships with equiangular tight frames
We study several interesting examples of Biangular Tight Frames (BTFs) -
basis-like sets of unit vectors admitting exactly two distinct frame angles
(ie, pairwise absolute inner products) - and examine their relationships with
Equiangular Tight Frames (ETFs) - basis-like systems which admit exactly one
frame angle.
We demonstrate a smooth parametrization BTFs, where the corresponding frame
angles transform smoothly with the parameter, which "passes through" an ETF
answers two questions regarding the rigidity of BTFs. We also develop a general
framework of so-called harmonic BTFs and Steiner BTFs - which includes the
equiangular cases, surprisingly, the development of this framework leads to a
connection with the famous open problem(s) regarding the existence of Mersenne
and Fermat primes. Finally, we construct a (chordally) biangular tight set of
subspaces (ie, a tight fusion frame) which "Pl\"ucker embeds" into an ETF.Comment: 19 page
The Impact of Full and Beneficial Use of San Juan-Chama Project Water by the City of Albuquerque on New Mexico\u27s Rio Grande Compact Obligations
In 2004, the New Mexico State Engineer approved a permit allowing the City of Albuquerque to divert from the Rio Grande the approximately 48,200 acre-feet per year of water it receives from the San Juan-Chama Project, a trans-basin diversion project that imports water from the Colorado River basin to the Rio Grande basin. Over the last 30 years, the City has consumed little of its San Juan-Chama water but rather has provided it to various third parties for their use. However, at the end of 2008, the City plans to commence surface diversion of its San Juan-Chama water and anticipates fully consuming its annual allocation by 2010.
Critics of the State Engineer\u27s decision to issue the City a permit for the diversion contend that full consumption by the City of its San Juan-Chama water eventually will result in failure by the State of New Mexico to satisfy its delivery requirements to Texas under the Rio Grande Compact. This paper analyzes this issue and evaluates the conditions of approval under which the City may use its San Juan-Chama water
Chiral density waves in quark matter within the Nambu--Jona-Lasinio model in an external magnetic field
A possibility of formation of static dual scalar and pseudoscalar density
wave condensates in dense quark matter is considered for the
Nambu--Jona-Lasinio model in an external magnetic field. Within a mean-field
approximation, the effective potential of the theory is obtained and its minima
are numerically studied; a phase diagram of the system is constructed. It is
shown that the presence of a magnetic field favors the formation of spatially
inhomogeneous condensate configurations at low temperatures and arbitrary
non-zero values of the chemical potential.Comment: 13 pages, 4 figure
Neutrino magnetohydrodynamics
A new neutrino magnetohydrodynamics (NMHD) model is formulated, where the
effects of the charged weak current on the electron-ion magnetohydrodynamic
fluid are taken into account. The model incorporates in a systematic way the
role of the Fermi neutrino weak force in magnetized plasmas. A fast
neutrino-driven short wavelengths instability associated with the magnetosonic
wave is derived. Such an instability should play a central role in strongly
magnetized plasma as occurs in supernovae, where dense neutrino beams also
exist. In addition, in the case of nonlinear or high frequency waves, the
neutrino coupling is shown to be responsible for breaking the frozen-in
magnetic field lines condition even in infinite conductivity plasmas.
Simplified and ideal NMHD assumptions were adopted and analyzed in detail
Scaling Behavior of Entanglement in Two- and Three-Dimensional Free Fermions
Exactly solving a spinless fermionic system in two and three dimensions, we
investigate the scaling behavior of the block entropy in critical and
non-critical phases. The scaling of the block entropy crucially depends on the
nature of the excitation spectrum of the system and on the topology of the
Fermi surface. Noticeably, in the critical phases the scaling violates the area
law and acquires a logarithmic correction \emph{only} when a well defined Fermi
surface exists in the system. When the area law is violated, we accurately
verify a conjecture for the prefactor of the logarithmic correction, proposed
by D. Gioev and I. Klich [quant-ph/0504151].Comment: 4 pages, 4 figure
Research Notes : Greenhouse determination of soybean tolerance to phytophthora rot
One method of determing field tolerance of soybeans to Phytophthora mega-sperma f. sp. glycinea (Hildeb.) Kaun & Erwin (Pmg) is to determine the percent of plant loss from emergence to maturity for cultivars grown in an infested field under conditions favorable for the disease (Buzzell and Anderson, 1982). Drawing upon the field results and the results of two unpublished greenhouse experiments (given below), a greenhouse technique similar to the field test was developed. 1962 Experiment : Cores of soil were obtained from a field known to be in-fested with Pmg race 1, the field having been used in a previous study (Ful-ton et al., 1961)
Lie symmetries for two-dimensional charged particle motion
We find the Lie point symmetries for non-relativistic two-dimensional charged
particle motion. These symmetries comprise a quasi-invariance transformation, a
time-dependent rotation, a time-dependent spatial translation and a dilation.
The associated electromagnetic fields satisfy a system of first-order linear
partial differential equations. This system is solved exactly, yielding four
classes of electromagnetic fields compatible with Lie point symmetries
Interplay of size and Landau quantizations in the de Haas-van Alphen oscillations of metallic nanowires
We examine the interplay between size quantization and Landau quantization in
the De Haas-Van Alphen oscillations of clean, metallic nanowires in a
longitudinal magnetic field for `hard' boundary conditions, i.e. those of an
infinite round well, as opposed to the `soft' parabolically confined boundary
conditions previously treated in Alexandrov and Kabanov (Phys. Rev. Lett. {\bf
95}, 076601 (2005) (AK)). We find that there exist {\em two} fundamental
frequencies as opposed to the one found in bulk systems and the three
frequencies found by AK with soft boundary counditions. In addition, we find
that the additional `magic resonances' of AK may be also observed in the
infinite well case, though they are now damped. We also compare the numerically
generated energy spectrum of the infinite well potential with that of our
analytic approximation, and compare calculations of the oscillatory portions of
the thermodynamic quantities for both models.Comment: Title changed, paper streamlined on suggestion of referrees, typos
corrected, numerical error in figs 2 and 3 corrected and final result
simplified -- two not three frequencies (as in the previous version) are
observed. Abstract altered accordingly. Submitted to Physical Review
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