27,811 research outputs found
Primary ideal theory for quadratic Jordan algebras
AbstractThe notion of a primary ideal was originally introduced in the study of noetherian rings, i.e., commutative associative rings with unity which have the maximum condition on ideals. In more recent years, this notion has been carried over to noncommutative associative rings and nonassociative rings (see [3]). In this paper, we shall give a definition and basic properties for (inner) primary ideals in a quadratic Jordan algebra based on the concept of prime ideals in Jordan algebras as discussed in [10]. We then give a necessary and sufficient condition for those algebras in which the well-known Lasker-Noether decomposition theorem holds. Finally, the analog of the tertiary ideal is discussed, and we show that in any quadratic Jordan algebra which has the maximum condition on ideals, all ideals can be represented as a finite intersection of tertiary ideals
Anomalous physical properties of underdoped weak-ferromagnetic superconductor RuSrEuCuO
Similar to the optimal-doped, weak-ferromagnetic (WFM induced by canted
antiferromagnetism, T = 131 K) and superconducting (T = 56 K)
RuSrGdCuO, the underdoped RuSrEuCuO
(T = 133 K, T = 36 K) also exhibited a spontaneous vortex state
(SVS) between 16 K and 36 K. The low field (20 G) superconducting
hysteresis loop indicates a weak and narrow Meissner state region of average
lower critical field B(T) = B(0)[1 -
(T/T)], with B(0) = 7 G and T = 16 K. The
vortex melting transition (T = 21 K) below T obtained from
the broad resistivity drop and the onset of diamagnetic signal indicates a
vortex liquid region due to the coexistence and interplay between
superconductivity and WFM order. No visible jump in specific heat was observed
near T for Eu- and Gd-compound. This is not surprising, since the
electronic specific heat is easily overshadowed by the large phonon and
weak-ferromagnetic contributions. Furthermore, a broad resistivity transition
due to low vortex melting temperature would also lead to a correspondingly
reduced height of any specific heat jump. Finally, with the baseline from the
nonmagnetic Eu-compound, specific heat data analysis confirms the magnetic
entropy associated with antiferromagnetic ordering of Gd (J = S = 7/2)
at 2.5 K to be close to ln8 as expected.Comment: 7 figure
b-quark decay in the collinear approximation
The semileptonic decay of a b-quark, b--> c l nu, is considered in the
relativistic limit where the decay products are approximately collinear.
Analytic results for the double differential lepton energy distributions are
given for finite charm-quark mass. Their use for the fast simulation of
isolated lepton backgrounds from heavy quark decays is discussed.Comment: 7 pages, 1 figure, submitted to Phys.Rev.
Dynamical Properties of a Growing Surface on a Random Substrate
The dynamics of the discrete Gaussian model for the surface of a crystal
deposited on a disordered substrate is investigated by Monte Carlo simulations.
The mobility of the growing surface was studied as a function of a small
driving force and temperature . A continuous transition is found from
high-temperature phase characterized by linear response to a low-temperature
phase with nonlinear, temperature dependent response. In the simulated regime
of driving force the numerical results are in general agreement with recent
dynamic renormalization group predictions.Comment: 10 pages, latex, 3 figures, to appear in Phys. Rev. E (RC
Expected seismicity and the seismic noise environment of Europa
Seismic data will be a vital geophysical constraint on internal structure of
Europa if we land instruments on the surface. Quantifying expected seismic
activity on Europa both in terms of large, recognizable signals and ambient
background noise is important for understanding dynamics of the moon, as well
as interpretation of potential future data. Seismic energy sources will likely
include cracking in the ice shell and turbulent motion in the oceans. We define
a range of models of seismic activity in Europa's ice shell by assuming each
model follows a Gutenberg-Richter relationship with varying parameters. A range
of cumulative seismic moment release between and Nm/yr is
defined by scaling tidal dissipation energy to tectonic events on the Earth's
moon. Random catalogs are generated and used to create synthetic continuous
noise records through numerical wave propagation in thermodynamically
self-consistent models of the interior structure of Europa. Spectral
characteristics of the noise are calculated by determining probabilistic power
spectral densities of the synthetic records. While the range of seismicity
models predicts noise levels that vary by 80 dB, we show that most noise
estimates are below the self-noise floor of high-frequency geophones, but may
be recorded by more sensitive instruments. The largest expected signals exceed
background noise by 50 dB. Noise records may allow for constraints on
interior structure through autocorrelation. Models of seismic noise generated
by pressure variations at the base of the ice shell due to turbulent motions in
the subsurface ocean may also generate observable seismic noise.Comment: 24 pages, 11 figures, Added in supplementary information from
revision submission, including 3 audio files with sonification of Europa
noise records. To view attachments, please download and extract the gzipped
tar source file listed under "Other formats
Site amplification, attenuation, and scattering from noise correlation amplitudes across a dense array in Long Beach, CA
For accurate seismic hazard evaluation, both the spatial and frequency-dependent variabilities in the amplitudes of earthquake ground motions are needed. While this information is rarely fully available due to the paucity of relevant seismic data, dense arrays like the 5200-geophone array in Long Beach, California provide the opportunity to study this amplitude variability. Here we show that ambient noise correlation amplitudes from the Long Beach array can be used to directly determine frequency-dependent site amplification factors. We analyze Rayleigh-wavefield amplitude gradients from ambient noise correlations that are processed so that relative amplitudes satisfy the wave equation and are therefore meaningful. Ultimately, we construct maps of site amplification across Long Beach at frequencies of 0.67, 1.0, and 2.0 Hz. These maps correlate well with local structure, notably the Newport-Inglewood Fault and also to known velocity structure. Through this process, we also obtain constraints on average attenuation structure and local scattering
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