538 research outputs found
A Note on The Influence of Soil Parent Material on Northern Red OAK Specific Gravity
Soil parent material was found to affect the specific gravity of northern red oak wood (Quercus rubra L.). The unextracted specific gravity of wood grown on limestone soils was 0.597 and that of wood grown on sandstone soils was 0.581. Site quality within a soil type had no significant effect. The relationship was independent of both rate of growth and latewood percentage
Fomin's conception of quantum cosmogenesis
The main aim of this paper is to extend the early approach to quantum
cosmogenesis provided by Fomin. His approach was developed independently to the
well-known Tryon description of the creation of the closed universe as a
process of quantum fluctuation of vacuum. We apply the Fomin concept to derive
the cosmological observables. We argue that Fomin's idea from his 1973 work, in
contrast to Tryon's one has impact on the current Universe models and the
proposed extension of his theory now can be tested by distant supernovae SNIa.
Fomin's idea of the creation of the Universe is based on the intersection of
two fundamental theories: general relativity and quantum field theory with the
contemporary cosmological models with dark energy. As a result of comparison
with contemporary approaches concerning dark energy, we found out that Fomin's
idea appears in the context of the present acceleration of the Universe
explanation: cosmological models with decaying vacuum. Contemporary it appears
in the form of Ricci scalar dark energy connected with the holographic
principle. We show also that the Fomin model admits the bounce instead of the
initial singularity. We demonstrate that the Fomin model of cosmogenesis can be
falsified and using SNIa data the values of model parameters is in agreement
with observations.Comment: 12 pages, 4 figures; (v2) 22 pages, references added, figures
improved; (v3) rewritten using revtex4; (v4) minor changes; (v5) improved
formulas and extended statistical analysi
Quantum Tunneling Effect in Oscillating Friedmann Cosmology
It is shown that the tunneling effect in quantum cosmology is possible not
only at the very beginning or the very end of the evolution, but also at the
moment of maximum expansion of the universe. A positive curvature expanding
Friedmann universe changes its state of evolution spontaneously and completely,
{\it without} any changes in the matter content, avoiding recollapse, and
falling into oscillations between the nonzero values of the scale factor. On
the other hand, an oscillating nonsingular universe can tunnel spontaneously to
a recollapsing regime. The probability of such kind of tunneling is given
explicitly. It is inversely related to the amount of nonrelativistic matter
(dust), and grows from a certain fixed value to unity if the negative
cosmological constant approaches zero.Comment: 18 pages Latex + 2 figures available by fax upon reques
Coseismic seafloor deformation in the trench region during the Mw8.8 Maule megathrust earthquake
The Mw 8.8 megathrust earthquake that occurred on 27 February 2010 offshore the Maule region of central Chile triggered a destructive tsunami. Whether the earthquake rupture extended to the shallow part of the plate boundary near the trench remains controversial. The up-dip limit of rupture during large subduction zone earthquakes has important implications for tsunami generation and for the rheological behavior of the sedimentary prism in accretionary margins. However, in general, the slip models derived from tsunami wave modeling and seismological data are poorly constrained by direct seafloor geodetic observations. We difference swath bathymetric data acquired across the trench in 2008, 2011 and 2012 and find ∼3-5 m of uplift of the seafloor landward of the deformation front, at the eastern edge of the trench. Modeling suggests this is compatible with slip extending seaward, at least, to within ∼6 km of the deformation front. After the Mw 9.0 Tohoku-oki earthquake, this result for the Maule earthquake represents only the second time that repeated bathymetric data has been used to detect the deformation following megathrust earthquakes, providing methodological guidelines for this relatively inexpensive way of obtaining seafloor geodetic data across subduction zone
Comparative palynological analysis of Lygodium venustum Sw. and L. volubile Sw. (Lygodiaceae)
T violation and the unidirectionality of time
An increasing number of experiments at the Belle, BNL, CERN, DA{\Phi}NE and
SLAC accelerators are confirming the violation of time reversal invariance (T).
The violation signifies a fundamental asymmetry between the past and future and
calls for a major shift in the way we think about time. Here we show that
processes which violate T symmetry induce destructive interference between
different paths that the universe can take through time. The interference
eliminates all paths except for two that represent continuously forwards and
continuously backwards time evolution. Evidence from the accelerator
experiments indicates which path the universe is effectively following. This
work may provide fresh insight into the long-standing problem of modeling the
dynamics of T violation processes. It suggests that T violation has previously
unknown, large-scale physical effects and that these effects underlie the
origin of the unidirectionality of time. It may have implications for the
Wheeler-DeWitt equation of canonical quantum gravity. Finally it provides a
view of the quantum nature of time itself.Comment: 24 pages, 5 figures. Final version accepted for publishing in
Foundations of Physics. The final publication is available at
http://www.springerlink.com/content/y3h4174jw2w78322
Quantum Pair Creation of Soliton Domain Walls
A large body of experimental evidence suggests that the decay of the false
vacuum, accompanied by quantum pair creation of soliton domain walls, can occur
in a variety of condensed matter systems. Examples include nucleation of charge
soliton pairs in density waves [eg. J. H. Miller, Jr. et al., Phys. Rev. Lett.
84, 1555 (2000)] and flux soliton pairs in long Josephon junctions. Recently,
Dias and Lemos [J. Math. Phys. 42, 3292 (2001)] have argued that the mass
of the soliton should be interpreted as a line density and a surface density,
respectively, for (2+1)-D and (3+1)-D systems in the expression for the pair
production rate. As the transverse dimensions are increased and the total mass
(energy) becomes large, thermal activation becomes suppressed, so quantum
processes can dominate even at relatively high temperatures. This paper will
discuss both experimental evidence and theoretical arguments for the existence
of high-temperature collective quantum phenomena
Do UK universities communicate their brands effectively through their websites?
This paper attempts to explore the effectiveness of UK universities’ websites. The area of branding in higher education has received increasing academic investigation, but little work has researched how universities demonstrate their brand promises through their websites. The quest to differentiate through branding can be challenging in the university context, however. It is argued that those institutions that have a strong distinctive image will be in a better position to face a changing future. Employing a multistage methodology, the web pages of twenty UK universities were investigated by using a combination of content and multivariable analysis. Results indicated ‘traditional values’ such as teaching and research were often well communicated in terms of online brand but ‘emotional values’ like social responsibility and the universities’ environments were less consistently communicated, despite their increased topicality. It is therefore suggested that emotional values may offer a basis for possible future online differentiation
PhOTO Zebrafish: A Transgenic Resource for In Vivo Lineage Tracing during Development and Regeneration
Background: Elucidating the complex cell dynamics (divisions, movement, morphological changes, etc.) underlying embryonic development and adult tissue regeneration requires an efficient means to track cells with high fidelity in space and time. To satisfy this criterion, we developed a transgenic zebrafish line, called PhOTO, that allows photoconvertible optical tracking of nuclear and membrane dynamics in vivo.
Methodology: PhOTO zebrafish ubiquitously express targeted blue fluorescent protein (FP) Cerulean and photoconvertible FP Dendra2 fusions, allowing for instantaneous, precise targeting and tracking of any number of cells using Dendra2 photoconversion while simultaneously monitoring global cell behavior and morphology. Expression persists through adulthood, making the PhOTO zebrafish an excellent tool for studying tissue regeneration: after tail fin amputation and photoconversion of a ~100µm stripe along the cut area, marked differences seen in how cells contribute to the new tissue give detailed insight into the dynamic process of regeneration. Photoconverted cells that contributed to the regenerate were separated into three distinct populations corresponding to the extent of cell division 7 days after amputation, and a subset of cells that divided the least were organized into an evenly spaced, linear orientation along the length of the newly regenerating fin.
Conclusions/Significance: PhOTO zebrafish have wide applicability for lineage tracing at the systems-level in the early embryo as well as in the adult, making them ideal candidate tools for future research in development, traumatic injury and regeneration, cancer progression, and stem cell behavior
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