2,183 research outputs found
Near-Limb Zeeman and Hanle Diagnostics
"Weak" magnetic-field diagnostics in faint objects near the bright solar disk
are discussed in terms of the level of non-object signatures, in particular, of
the stray light in telescopes. Calculated dependencies of the stray light
caused by diffraction at the 0.5-, 1.6-, and 4-meter entrance aperture are
presented. The requirements for micro-roughness of refractive and reflective
primary optics are compared. Several methods for reducing the stray light (the
Lyot coronagraphic technique, multiple stages of apodizing in the focal and
exit pupil planes, apodizing in the entrance aperture plane with a special
mask), and reducing the random and systematic errors are noted. An acceptable
level of stray light in telescopes is estimated for the V-profile recording
with a signal-to-noise ratio greater than three. Prospects for the limb
chromosphere magnetic measurements are indicated.Comment: 11 pages, 3 figure
The hyphenation of the void: from eastern ecology to western architecture
This thesis explores the cultural cross-fertilization between the orient and
the occident by studying the eastern concept of the void that brings all
components of the universe into a fluid continuous whole. This void is not
in binary opposition to the full as in western dualism but rather co-exists
with the full in a dynamic balance and complementary position following
the Taoist philosophy. It is thus essentially characterized by its perpetual
mutation, its transience. In this perspective, the oriental void emerges as a
set of connections that incessantly evolve through time: the hyphenation
of the void.
My research proposes to incorporate this interpretation of the oriental
void into the occidental architectural approach. Therefore, it develops
the idea of conceptual and material hyphens that are familiar images to
western culture and that also provide tangible and material expressions
to the hyphenation. Conceptual hyphens serve as a sensible metaphor
for the elusive principles of the void while material hyphens give
materiality and palpability to the abstract notion of the void. These
definitions are not mutually exclusive so that a hyphen can be both
conceptual and material at times. Hyphens are then used as design
devices in the architectural practice of the void. Their combination
generates the architectural projects’ narratives, material substance and,
affects their visual representations.
The subsequent architecture of the void appears as an organic entity
which grows and decays through its endless interactions with the
surrounding environment. The latter is not restricted to the usual urban
and architectural conditions but expands to socio-cultural, economical
and political parameters. This architecture is thus always in the process
of becoming amid a wide ecosystem and prompts the awakening of its
users to the present moment in the current situation. In consequence, it
generates an ecology of the void where architecture is experienced in
the Heideggerian sense as a built thing that enables its users to dwell in
unison with the universe.
The issue of hyphenation is in fact a reflection on my own status an inbetweener
drifting in the east–west intercultural flow of our nomadic
contemporary society. The thesis represents, therefore, an investigation
into my personal way of life
Supersymmetry Breaking and Dilaton Stabilization in String Gas Cosmology
In this Note we study supersymmetry breaking via gaugino condensation in
string gas cosmology. We show that the same gaugino condensate which is
introduced to stabilize the dilaton breaks supersymmetry. We study the
constraints on the scale of supersymmetry breaking which this mechanism leads
to.Comment: 11 page
Pressure and linear heat capacity in the superconducting state of thoriated UBe13
Even well below Tc, the heavy-fermion superconductor (U,Th)Be13 has a large
linear term in its specific heat. We show that under uniaxial pressure, the
linear heat capacity increases in magnitude by more than a factor of two. The
change is reversible and suggests that the linear term is an intrinsic property
of the material. In addition, we find no evidence of hysteresis or of latent
heat in the low-temperature and low-pressure portion of the phase diagram,
showing that all transitions in this region are second order.Comment: 5 pages, 4 figure
Phase diagram and optical conductivity of the one-dimensional spinless Holstein model
The effects of quantum lattice fluctuations on the Peierls transition and the
optical conductivity in the one-dimensional Holstein model of spinless fermions
have been studied by developing an analytical approach, based on the unitary
transformation method. We show that when the electron-phonon coupling constant
decreases to a finite critical value the Peierls dimerization is destroyed by
the quantum lattice fluctuations. The dimerization gap is much more reduced by
the quantum lattice fluctuations than the phonon order parameter. The
calculated optical conductivity does not have the inverse-square-root
singularity but have a peak above the gap edge and there exists a significant
tail below the peak. The peak of optical-conductivity spectrum is not directly
corresponding to the dimerized gap. Our results of the phase diagram and the
spectral-weight function agree with those of the density matrix renormalization
group and the exact diagonalization methods.Comment: 9 pages, 4 figures include
Background field boundary conditions for affine Toda field theories
Classical integrability is investigated for affine Toda field theories in the
presence of a constant background tensor field. This leads to a further set of
discrete possibilities for integrable boundary conditions depending upon the
time-derivative of the fields at the boundary but containing no free parameters
other than the bulk coupling constant.Comment: 21 pages, harvma
Scaling and finte-size-scaling in the two dimensional random-coupling Ising ferromagnet
It is shown by Monte Carlo method that the finite size scaling (FSS) holds in
the two dimensional random-coupled Ising ferromagnet. It is also demonstrated
that the form of universal FSS function constructed via novel FSS scheme
depends on the strength of the random coupling for strongly disordered cases.
Monte Carlo measurements of thermodynamic (infinite volume limit) data of the
correlation length () up to along with measurements of
the fourth order cumulant ratio (Binder's ratio) at criticality are reported
and analyzed in view of two competing scenarios. It is demonstrated that the
data are almost exclusively consistent with the scenario of weak universality.Comment: 9 pages, 4figuer
Fano resonances and Aharonov-Bohm effects in transport through a square quantum dot molecule
We study the Aharonov-Bohm effect in a coupled 22 quantum dot array
with two-terminals. A striking conductance dip arising from the Fano
interference is found as the energy levels of the intermediate dots are
mismatched, which is lifted in the presence of a magnetic flux. A novel five
peak structure is observed in the conductance for large mismatch. The
Aharonov-Bohm evolution of the linear conductance strongly depends on the
configuration of dot levels and interdot and dot-lead coupling strengths. In
addition, the magnetic flux and asymmetry between dot-lead couplings can induce
the splitting and combination of the conductance peak(s).Comment: 15 pages, 7 figures, Revtex, to be published in Phys. Rev.
Separate and combined effects of oligofructose and inulin on post-weaning coli bacillosis and weight gain: a preliminary study
Trends for a reduction in the use of dietary antibiotic growth promoters have caused increased interest in the use of alternative feed additives to maintain 'gut health' after weaning. Oligofructose and inulin are 'prebiotic' fructan-containing carbohydrates purported to enhance 'gut health' in newly-weaned pigs by altering microbial diversity (Konstantinov, et al., 2003). However, their effects using a challenge model of post-weaning colibacillosis (PWC) have never been examined. The aim of the present study was to compare the separate and combined effects of oligofructose and inulin supplementation on the occurrence of diarrhoea and the weight performance in piglets experimentally challenged with enterotoxigenic E. coli (ETEC)
Anomalous scaling of a passive scalar in the presence of strong anisotropy
Field theoretic renormalization group and the operator product expansion are
applied to a model of a passive scalar field, advected by the Gaussian strongly
anisotropic velocity field. Inertial-range anomalous scaling behavior is
established, and explicit asymptotic expressions for the n-th order structure
functions of scalar field are obtained; they are represented by superpositions
of power laws with nonuniversal (dependent on the anisotropy parameters)
anomalous exponents. In the limit of vanishing anisotropy, the exponents are
associated with tensor composite operators built of the scalar gradients, and
exhibit a kind of hierarchy related to the degree of anisotropy: the less is
the rank, the less is the dimension and, consequently, the more important is
the contribution to the inertial-range behavior. The leading terms of the even
(odd) structure functions are given by the scalar (vector) operators. For the
finite anisotropy, the exponents cannot be associated with individual operators
(which are essentially ``mixed'' in renormalization), but the aforementioned
hierarchy survives for all the cases studied. The second-order structure
function is studied in more detail using the renormalization group and
zero-mode techniques.Comment: REVTEX file with EPS figure
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