819 research outputs found
Improving navigation conditions in the Westerschelde and managing its estuarine environment: how to harmonize accessibility, safetyness and naturalness?
The Bailey Point Region and Other Muskox Refugia in the Canadian Arctic: A Short Review
The muskox (Ovibos moschatus) is widely distributed over much of arctic Canada but only at a few locations do their densities remain high and populations relatively stable. These refugia constitute the most favourable muskox ranges in the Canadian Arctic Archipelago .... Refugia for muskoxen in the High Arctic include lowlands on eastern Axel Heiberg Island in the Mokka Fiord region, the lowlands of northeastern Devon Island, and the Bailey Point region of Melville Island .... All of those regions historically have supported high densities of muskoxen from time to time but the Bailey Point region must be considered the best habitat for muskoxen in the Canadian High Arctic. ..
Gene expression-phenotype associations in adults with eosinophilic esophagitis
Background: Gene expression patterns have not been extensively examined in the context of clinical features of eosinophilic esophagitis (EoE). Aims: To assess whether gene expression is associated with clinically defined phenotypes in adults with EoE. Methods: This was an analysis of prospectively collected esophageal biopsies in newly diagnosed EoE patients. We determined differential gene expression with a 94 gene panel in relation to clinical features and phenotypes. These included: endoscopic findings of esophageal rings, stricture, narrowing, linear furrows, exudates, edema, and dilation; an allergic phenotype; an inflammatory phenotype, and a fibrostenotic phenotype. Results: In 89 EoE cases analyzed, patients with exudates on endoscopy had multiple differences in gene expression compared to patients without exudates, though patients with exudates also had higher eosinophil counts (172 vs 106 eos/hpf; p =.01). Genes associated with esophageal narrowing included CCL26 (q-value = 0.028), ALOX15 (q = 0.011), GRK5 (q = 0.029), CPA3 (q = 0.012), and TRIM2 (q = 0.0027). TRIM2 was also associated with the fibrostenotic phenotype (q = 0.0051). No genes were associated with the inflammatory or atopic phenotypes, or with dilation. Conclusions: Multiple genes are associated with exudates, possibly related to higher eosinophil counts. However, a number of genes, including those related to both inflammation and remodelling, are associated with esophageal narrowing. In particular, TRIM2 is associated with clinical fibrotic phenotypes
The Coherent State Representation of Quantum Fluctuations in the Early Universe
Using the squeezed state formalism the coherent state representation of
quantum fluctuations in an expanding universe is derived. It is shown that this
provides a useful alternative to the Wigner function as a phase space
representation of quantum fluctuations. The quantum to classical transition of
fluctuations is naturally implemented by decohering the density matrix in this
representation. The entropy of the decohered vacua is derived. It is shown that
the decoherence process breaks the physical equivalence between vacua that
differ by a coordinate dependent phase generated by a surface term in the
Lagrangian. In particular, scale invariant power spectra are only obtained for
a special choice of surface term.Comment: 25 pages in revtex 3. This version is completely revised with
corrections and significant new calculation
Prospective assessment of serum periostin as a biomarker for diagnosis and monitoring of eosinophilic oesophagitis
Background Periostin is highly expressed in eosinophilic oesophagitis (EoE), but has not been extensively studied as a non-invasive biomarker. Aim To assess whether serum periostin distinguished EoE from controls at baseline, had utility for monitoring treatment response, or was associated with IL-13 levels. Methods This was a sub-analysis of a prospective cohort study of adults undergoing out-patient upper endoscopy. Incident cases of EoE were diagnosed per consensus guidelines. Controls were subjects with either GERD or dysphagia without EoE. EoE patients were treated with swallowed/topical steroids and had repeat endoscopy/biopsy. Serum periostin levels for cases and controls were compared at baseline, and pre/post-treatment levels were compared for cases. Serum IL-13 and tissue expression of periostin were also assessed. Results A total of 61 incident EoE cases and 87 controls were analysed. Despite a marked increase in tissue periostin expression in cases, the median baseline serum periostin level was only slightly higher in cases than controls (22.1 ng/mL vs. 20.7; P = 0.04); there was no change in post-treatment levels. There was also no difference in serum periostin for cases by histologic response or atopic status. There was a strong trend towards higher serum IL-13 levels in cases in the highest periostin quartile (57.1 pg/mL vs. 2.6; P = 0.07). Conclusions Serum periostin levels were similar in cases and controls, and there were no changes post-treatment. Given elevated IL-13 levels in the EoE patients with the highest periostin levels, future studies could explore periostin as a biomarker in EoE, perhaps in the setting of anti-IL-13 therapy
SN1A data and the CMB of Modified Curvature at short and long distances
The SN1a data, although inconclusive, when combined with other observations
makes a strong case that our universe is presently dominated by dark energy. We
investigate the possibility that large distance modifications of the curvature
of the universe would perhaps offer an alternative explanation of the
observation. Our calculations indicate that a universe made up of no dark
energy but instead, with a modified curvature at large scales, is not
scale-invariant, therefore quite likely it is ruled out by the CMB
observations. The sensitivity of the CMB spectrum is checked for the whole
range of mode modifications of large or short distance physics. The spectrum is
robust against modifications of short-distance physics and the UV cutoff when:
the initial state is the adiabatic vacuum, and the inflationary background
space is de Sitter.Comment: 13 pages, 2 eps figures, typos corrected, references added; to appear
in Phys. Rev.
Condensate cosmology -- dark energy from dark matter
Imagine a scenario in which the dark energy forms via the condensation of
dark matter at some low redshift. The Compton wavelength therefore changes from
small to very large at the transition, unlike quintessence or metamorphosis. We
study CMB, large scale structure, supernova and radio galaxy constraints on
condensation by performing a 4 parameter likelihood analysis over the Hubble
constant and the three parameters associated with Q, the condensate field:
Omega_Q, w_f and z_t (energy density and equation of state today, and redshift
of transition). Condensation roughly interpolates between Lambda CDM (for large
z_t) and sCDM (low z_t) and provides a slightly better fit to the data than
Lambda CDM. We confirm that there is no degeneracy in the CMB between H and z_t
and discuss the implications of late-time transitions for the Lyman-alpha
forest. Finally we discuss the nonlinear phase of both condensation and
metamorphosis, which is much more interesting than in standard quintessence
models.Comment: 13 pages, 13 colour figures. Final version with discussion of TE
cross-correlation spectra for condensation and metamorphosis in light of the
WMAP result
Particle creation, classicality and related issues in quantum field theory: II. Examples from field theory
We adopt the general formalism, which was developed in Paper I
(arXiv:0708.1233) to analyze the evolution of a quantized time-dependent
oscillator, to address several questions in the context of quantum field theory
in time dependent external backgrounds. In particular, we study the question of
emergence of classicality in terms of the phase space evolution and its
relation to particle production, and clarify some conceptual issues. We
consider a quantized scalar field evolving in a constant electric field and in
FRW spacetimes which illustrate the two extreme cases of late time adiabatic
and highly non-adiabatic evolution. Using the time-dependent generalizations of
various quantities like particle number density, effective Lagrangian etc.
introduced in Paper I, we contrast the evolution in these two limits bringing
out key differences between the Schwinger effect and evolution in the de Sitter
background. Further, our examples suggest that the notion of classicality is
multifaceted and any one single criterion may not have universal applicability.
For example, the peaking of the phase space Wigner distribution on the
classical trajectory \emph{alone} does not imply transition to classical
behavior. An analysis of the behavior of the \emph{classicality parameter},
which was introduced in Paper I, leads to the conclusion that strong particle
production is necessary for the quantum state to become highly correlated in
phase space at late times.Comment: RevTeX 4; 27 pages; 18 figures; second of a series of two papers, the
first being arXiv:0708.1233 [gr-qc]; high resolution figures available from
the authors on reques
Probing the Environment with Galaxy Dynamics
I present various projects to study the halo dynamics of elliptical galaxies.
This allows one to study the outer mass and orbital distributions of
ellipticals in different environments, and the inner distributions of groups
and clusters themselves.Comment: 5 pages, 2 figs, to appear in Proc. ESO Workshop, Groups of Galaxies
in the Nearby Universe (5-9 Dec 2005), eds. I. Saviane, V. Ivanov & J.
Borissova (Springer-Verlag
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