4,162 research outputs found
Population Growth and Other Statistics of Middle-sized Irish Towns. General Research Series Paper No. 85, April 1976
The basic aim of the study is the presentation of tables of comparative
statistical data relating to 97 towns with population 5OO-1O,OOO in
1971 and analyses of such data. The exclusion of the four County Boroughs
and Dun Laoghaire together with twelve other large towns and all small
towns and villages, was to impart a degree of homogeneity to the inquiry, as
regards function of town. The 97 towns range from Mullingar, the largest
with a population of 9,245 to Cootehill with 1,542
Composite Overwrapped Pressure Vessels, A Primer
Due to the extensive amount of detailed information that has been published on composite overwrapped pressure vessels (COPVs), this document has been written to serve as a primer for those who desire an elementary knowledge of COPVs and the factors affecting composite safety. In this application, the word "composite" simply refers to a matrix of continuous fibers contained within a resin and wrapped over a pressure barrier to form a vessel for gas or liquid containment. COPVs are currently used at NASA to contain high pressure fluids in propulsion, science experiments, and life support applications. They have a significant weight advantage over all metal vessels but require unique design, manufacturing, and test requirements. COPVs also involve a much more complex mechanical understanding due to the interplay between the composite overwrap and the inner liner. A metallic liner is typically used in a COPV as a fluid permeation barrier. The liner design concepts and requirements have been borrowed from all-metal vessels. However, application of metallic vessel design standards to a very thin liner is not straightforward. Different failure modes exist for COPVs than for all-metal vessels, and understanding of these failure modes is at a much more rudimentary level than for metal vessels
Probing the extreme realm of AGN feedback in the massive galaxy cluster, RX J1532.9+3021
We present a detailed Chandra, XMM-Newton, VLA and HST analysis of one of the
strongest cool core clusters known, RX J1532.9+3021 (z=0.3613). Using new, deep
90 ks Chandra observations, we confirm the presence of a western X-ray cavity
or bubble, and report on a newly discovered eastern X-ray cavity. The total
mechanical power associated with these AGN-driven outflows is (22+/-9)*10^44
erg/s, and is sufficient to offset the cooling, indicating that AGN feedback
still provides a viable solution to the cooling flow problem even in the
strongest cool core clusters. Based on the distribution of the optical
filaments, as well as a jet-like structure seen in the 325 MHz VLA radio map,
we suggest that the cluster harbours older outflows along the north to south
direction. The jet of the central AGN is therefore either precessing or
sloshing-induced motions have caused the outflows to change directions. There
are also hints of an X-ray depression to the north aligned with the 325 MHz
jet-like structure, which might represent the highest redshift ghost cavity
discovered to date. We further find evidence of a cold front (r=65kpc) that
coincides with the outermost edge of the western X-ray cavity and the edge of
the radio mini-halo. The common location of the cold front with the edge of the
radio mini-halo supports the idea that the latter originates from electrons
being reaccelerated due to sloshing induced turbulence. Alternatively, its
coexistence with the edge of the X-ray cavity may be due to cool gas being
dragged out by the outburst. We confirm that the central AGN is highly
sub-Eddington and conclude that a >10^10M_Sun or a rapidly spinning black hole
is favoured to explain both the radiative-inefficiency of the AGN and the
powerful X-ray cavities.Comment: Accepted for publication to ApJ (minor corrections), 16 pages, 16
figures, 5 tables. Full resolution at http://www.stanford.edu/~juliehl/M1532
Hot Property in New Zealand: Empirical Evidence of Housing Bubbles in the Metropolitan
Using recently developed statistical methods for testing and dating exhuberant behavior in asset prices we document evidence of episodic bubbles in the New Zealand property market over the past two decades. The results show clear evidence of a broad-based New Zealand housing bubble that began in 2003 and collapsed over mid 2007 to early 2008 with the onset of the worldwide recession and the financial crisis. New methods of analyzing market contagion are also developed and are used to examine spillovers from the Auckland property market to the other metropolitan centres. Evidence from the latest data reveals that the greater Auckland metropolitan area is currently experiencing a new property bubble that began in 2013. But there is no evidence yet of any contagion effect of this bubble on the other centres, in contrast to the earlier bubble over 2003-2008 for which there is evidence of transmission of the housing bubble from Auckland to the other centres. One of our primary conclusions is that the expensive nature of New Zealand real estate relative to potential earnings in rents is partly due to the sustained market exuberance that produced the broad based bubble in house prices during the last decade and that has continued through the most recent bubble experienced in the Auckland region since 2013
Coupled phonon-ripplon modes in a single wire of electrons on the liquid-helium surface
The coupled phonon-ripplon modes of the quasi-one-dimensional electron chain
on the liquid helium sutface are studied. It is shown that the electron-ripplon
coupling leads to the splitting of the collective modes of the wire with the
appearance of low-frequency modes and high-frequency optical modes starting
from threshold frequencies. The effective masses of an electron plus the
associated dimple for low frequency modes are estimated and the values of the
threshold frequencies are calculated. The results obtained can be used in
experimental attempts to observe the phase transition of the electron wire into
a quasi-ordered phase.Comment: 5 pages, 1 figure, Physical Review (in press
The Determination of Nuclear Level Densities from Experimental Information -
A novel Information Theory based method for determining the density of states
from prior information is presented. The energy dependence of the density of
states is determined from the observed number of states per energy interval and
model calculations suggest that the method is sufficiently reliable to
calculate the thermal properties of nuclei over a reasonable temperature range.Comment: 7 pages + 6 eps figures, REVTEX 3.
Melting of the classical bilayer Wigner crystal: influence of the lattice symmetry
The melting transition of the five different lattices of a bilayer crystal is
studied using the Monte-Carlo technique. We found the surprising result that
the square lattice has a substantial larger melting temperature as compared to
the other lattice structures, which is a consequence of the specific topology
of the temperature induced defects. A new melting criterion is formulated which
we show to be universal for bilayers as well as for single layer crystals.Comment: 4 pages, 5 figures (postscript files). Accepted in Physical Review
Letter
Exchange Frequencies in the 2d Wigner crystal
Using Path Integral Monte Carlo we have calculated exchange frequencies as
electrons undergo ring exchanges in a ``clean'' 2d Wigner crystal as a function
of density. The results show agreement with WKB calculations at very low
density, but show a more rapid increase with density near melting. Remarkably,
the exchange Hamiltonian closely resembles the measured exchanges in 2d He.
Using the resulting multi-spin exchange model we find the spin Hamiltonian for
r_s \leq 175 \pm 10 is a frustrated antiferromagnetic; its likely ground state
is a spin liquid. For lower density the ground state will be ferromagnetic
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