23,156 research outputs found
Condensation phase transitions of symmetric conserved-mass aggregation model on complex networks
We investigate condensation phase transitions of symmetric conserved-mass
aggregation (SCA) model on random networks (RNs) and scale-free networks (SFNs)
with degree distribution . In SCA model, masses diffuse
with unite rate, and unit mass chips off from mass with rate . The
dynamics conserves total mass density . In the steady state, on RNs and
SFNs with for , we numerically show that SCA
model undergoes the same type condensation transitions as those on regular
lattices. However the critical line depends on network
structures. On SFNs with , the fluid phase of exponential mass
distribution completely disappears and no phase transitions occurs. Instead,
the condensation with exponentially decaying background mass distribution
always takes place for any non-zero density. For the existence of the condensed
phase for at the zero density limit, we investigate one
lamb-lion problem on RNs and SFNs. We numerically show that a lamb survives
indefinitely with finite survival probability on RNs and SFNs with ,
and dies out exponentially on SFNs with . The finite life time
of a lamb on SFNs with ensures the existence of the
condensation at the zero density limit on SFNs with at which
direct numerical simulations are practically impossible. At ,
we numerically confirm that complete condensation takes place for any on RNs. Together with the recent study on SFNs, the complete condensation
always occurs on both RNs and SFNs in zero range process with constant hopping
rate.Comment: 6 pages, 6 figure
Macrostructural analysis : unravelling polyphase glacitectonic histories
Many Pleistocene glacial profiles look extremely simple, comprising till, or glacitectonite, overlying
older sediments or bedrock (Figure 4.1). In more complex sequences the till may itself be overlain by
younger sediments laid down as the ice retreated or during a completely separate, later phase of
advance. Macroscopically, subglacial traction tills (Evans et al., 2007) are typically massive,
unstructured deposits suggesting that it should be relatively straightforward to unravel the
glacitectonic deformation history recorded by the sequence. Many reconstructions do indeed look
very simple, slabs of sediment have been tilted and stacked and then overridden by the glacier to
cap the structure with till. Added to this is the use of vertical exaggeration which makes the whole
structure look like alpine tectonics (for an example see fig. 5 in van Gijssel, 1987). Dropping the
exaggeration led to the recognition that actually we were looking at much more horizontal
structures, i.e. overriding nappes and not imbricated slabs (van der Wateren, 1987).
Traditionally (van der Meer, 1987) glaciotectonics was thought to relate to large structures
like big push moraines and not to smaller structures like drag structures underneath tills (Figure 4.2),
let alone to the tills themselves. With the notion that deforming bed tills are tectonically and not
sedimentologically structured and could be regarded as tectomicts (Menzies et al., 2006), comes the
realisation that glacitectonics happens across a wide range of scales, from the microscopic to tens of
kilometres. Only by realising the full range of glaciotectonic scales can we hope to understand the
processes
An Algorithm to Simplify Tensor Expressions
The problem of simplifying tensor expressions is addressed in two parts. The
first part presents an algorithm designed to put tensor expressions into a
canonical form, taking into account the symmetries with respect to index
permutations and the renaming of dummy indices. The tensor indices are split
into classes and a natural place for them is defined. The canonical form is the
closest configuration to the natural configuration. In the second part, the
Groebner basis method is used to simplify tensor expressions which obey the
linear identities that come from cyclic symmetries (or more general tensor
identities, including non-linear identities). The algorithm is suitable for
implementation in general purpose computer algebra systems. Some timings of an
experimental implementation over the Riemann package are shown.Comment: 15 pages, Latex2e, submitted to Computer Physics Communications:
Thematic Issue on "Computer Algebra in Physics Research
Format zorgpad Voeding bij kanker
Het zorgpad ‘Voeding bij kanker’ beschrijft het (logistiek) pad dat de oncologische patiënt doorloopt binnen de voedingszorg vanaf het moment dat screening op behoefte aan voedingszorg plaatsvindt en verwijzing naar de diëtist tot en met follow-up of palliatieve fase. Hierbij zijn het format en de indeling aangehouden van de IKNL-formats van (niet-)tumorspecifieke zorgpade
A group processes approach to antiscience beliefs and endorsement of “alternative facts”
The global spread of antiscience beliefs, misinformation, fake news, and conspiracy theories is posing a threat to the well-being of individuals and societies worldwide. Accordingly, research on why people increasingly doubt science and endorse “alternative facts” is flourishing. Much of this work has focused on identifying cognitive biases and individual differences. Importantly, however, the reasons that lead people to question mainstream scientific findings and share misinformation are also inherently tied to social processes that emerge out of divisive commitments to group identities and worldviews. In this special issue, we focus on the important and thus far neglected role of group processes in motivating science skepticism. The articles that feature in this special issue cover three core areas: the group-based roots of antiscience attitudes; the intergroup dynamics between science and conspiratorial thinking; and finally, insights about science denial related to the COVID-19 pandemic. Across all articles, we highlight the role of worldviews, identities, norms, religion, and other inter- and intragroup processes that shape antiscientific attitudes. We hope that this collection will inspire future research endeavors that take a group processes approach to the social psychological study of science skepticism. </jats:p
Dynamics of the Globular Cluster System Associated with M87 (NGC 4486). II. Analysis
We present a dynamical analysis of the globular cluster system associated
with M87 (= NGC 4486), the cD galaxy near the dynamical center of the Virgo
cluster. The analysis utilizes a new spectroscopic and photometric database
which is described in a companion paper (Hanes et al. 2001). Using a sample of
278 globular clusters with measured radial velocities and metallicities, and
new surface density profiles based on wide-field Washington photometry, we
study the dynamics of the M87 globular cluster system both globally --- for the
entire cluster sample --- and separately --- for the metal-rich and metal-poor
globular cluster samples. This constitutes the largest sample of radial
velocities for pure Population II tracers yet assembled for any galaxy. We
discuss the implications of our findings for models for the formation of giant
elliptical galaxies, globular cluster systems, and the Virgo cluster.
(ABRIDGED)Comment: 28 pages, 19 postscript figures, 1 jpeg image. See
http://www.physics.rutgers.edu/ast/ast-rap.html to download the manuscript
with higher quality figures. Accepted for publication in the Astrophysical
Journa
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