383 research outputs found
Lessons from Love-Locks: The archaeology of a contemporary assemblage
This document is the Accepted Manuscript version. The final, definitive version of this paper has been published in Journal of Material Culture, November 2017, published by SAGE Publishing, All rights reserved.Loss of context is a challenge, if not the bane, of the ritual archaeologistâs craft. Those who research ritual frequently encounter difficulties in the interpretation of its often tantalisingly incomplete material record. Careful analysis of material remains may afford us glimpses into past ritual activity, but our often vast chronological separation from the ritual practitioners themselves prevent us from seeing the whole picture. The archaeologist engaging with structured deposits, for instance, is often forced to study ritual assemblages post-accumulation. Many nuances of its formation, therefore, may be lost in interpretation. This paper considers what insights an archaeologist could gain into the place, people, pace, and purpose of deposition by recording an accumulation of structured deposits during its formation, rather than after. To answer this, the paper will focus on a contemporary depositional practice: the love-lock. This custom involves the inscribing of names/initials onto a padlock, its attachment to a bridge or other public structure, and the deposition of the corresponding key into the water below; a ritual often enacted by a couple as a statement of their romantic commitment. Drawing on empirical data from a three-year diachronic site-specific investigation into a love-lock bridge in Manchester, UK, the author demonstrates the value of contemporary archaeology in engaging with the often enigmatic material culture of ritual accumulations.Peer reviewe
Nonradial oscillations of quark stars
Recently, it has been reported that a candidate for a quark star may have
been observed. In this article, we pay attention to quark stars with radiation
radii in the reported range. We calculate nonradial oscillations of -, -
and -modes. Then, we find that the dependence of the -mode
quasi-normal frequency on the bag constant and stellar radiation radius is very
strong and different from that of the lowest -mode quasi-normal
frequency. Furthermore we deduce a new empirical formula between the -mode
frequency of gravitational waves and the parameter of the equation of state for
quark stars. The observation of gravitational waves both of the -mode and of
the lowest -mode would provide a powerful probe for the equation of
state of quark matter and the properties of quark stars.Comment: 13 pages, 6 figures, accepted for publication in Phys.Rev.
Decontamination of black peppercorn (Piper nigrum L.) using microwave-generated low pressure air plasma
The preliminary results show that microwave-generated low pressure air plasmas could be a very efficient method for the decontamination of spices since the population of a microorganism (Bacillus subtilis) commonly found in black pepper (Piper nigrum L.) was significantly reduced on test substrates in a very short period of time. Based on the experimental results, a laboratory apparatus was developed for the sterilisation of spices
Radiative Falloff in Neutron Star Spacetimes
We systematically study late-time tails of scalar waves propagating in
neutron star spacetimes. We consider uniform density neutron stars, for which
the background spacetime is analytic and the compaction of the star can be
varied continously between the Newtonian limit 2M/R << 1 and the relativistic
Buchdahl limit 2M/R = 8/9. We study the reflection of a finite wave packet off
neutron stars of different compactions 2M/R and find that a Newtonian, an
intermediate, and a highly relativistic regime can be clearly distinguished. In
the highly relativistic regime, the reflected signal is dominated by
quasi-periodic peaks, which originate from the wave packet bouncing back and
forth between the center of the star and the maximum of the background
curvature potential at R ~ 3 M. Between these peaks, the field decays according
to a power-law. In the Buchdahl limit 2M/R -> 8/9 the light travel time between
the center and the maximum or the curvature potential grows without bound, so
that the first peak arrives only at infinitely late time. The modes of neutron
stars can therefore no longer be excited in the ultra-relativistic limit, and
it is in this sense that the late-time radiative decay from neutron stars
looses all its features and gives rise to power-law tails reminiscent of
Schwarzschild black holes.Comment: 10 pages, 7 figures, to appear in PR
Gravitational waves from a test particle scattered by a neutron star: Axial mode case
Using a metric perturbation method, we study gravitational waves from a test
particle scattered by a spherically symmetric relativistic star. We calculate
the energy spectrum and the waveform of gravitational waves for axial modes.
Since metric perturbations in axial modes do not couple to the matter fluid of
the star, emitted waves for a normal neutron star show only one peak in the
spectrum, which corresponds to the orbital frequency at the turning point,
where the gravitational field is strongest. However, for an ultracompact star
(the radius ), another type of resonant periodic peak appears in
the spectrum. This is just because of an excitation by a scattered particle of
axial quasinormal modes, which were found by Chandrasekhar and Ferrari. This
excitation comes from the existence of the potential minimum inside of a star.
We also find for an ultracompact star many small periodic peaks at the
frequency region beyond the maximum of the potential, which would be due to a
resonance of two waves reflected by two potential barriers (Regge-Wheeler type
and one at the center of the star). Such resonant peaks appear neither for a
normal neutron star nor for a Schwarzschild black hole. Consequently, even if
we analyze the energy spectrum of gravitational waves only for axial modes, it
would be possible to distinguish between an ultracompact star and a normal
neutron star (or a Schwarzschild black hole).Comment: 21 pages, revtex, 11 figures are attached with eps files Accepted to
Phys. Rev.
The Pennyâs Dropped: Renegotiating the contemporary coin deposit
This is the Accepted Manuscript of the following article: Ceri Houlbrook, âThe pennyâs dropped: Renegotiating the contemporary coin depositâ, Journal of Material Culture, Vol. 20(2): 173-189, March 2015. The final published version is available at: http://journals.sagepub.com/doi/pdf/10.1177/1359183515577120#articleCitationDownloadContainer © 2015, © SAGE Publications.This article examines the status of coins as contemporary deposits in the British Isles. With a focus on both historical and contemporary sites, from the Neolithic long barrow of Waylandâs Smithy, Oxfordshire, to the plethora of wishing-wells and coin-trees distributed across the British Isles, it demonstrates the popularity of coins as ritual deposits. The author considers how they are perceived and treated by site custodians, and concludes with a case study of an archaeological excavation, the 2013 Ardmaddy Wishing-Tree Project, which recovered a large amount of contemporary coin deposits. This article does not aim to locate itself within the debates of site custodianship and accessibility, nor does it propose to address the broader dilemmas of a siteâs ritual continuity or resurgence. Instead, its aim is to encourage archaeologists to consider the contemporary deposit as an integral part of the ritual narrative of a site, rather than as disposable âritual litterâ.Peer reviewedFinal Accepted Versio
Restricting quark matter models by gravitational wave observation
We consider the possibilities for obtaining information about the equation of
state for quark matter by using future direct observational data on
gravitational waves. We study the nonradial oscillations of both fluid and
spacetime modes of pure quark stars. If we observe the and the lowest
modes from quark stars, by using the simultaneously obtained
radiation radius we can constrain the bag constant with reasonable
accuracy, independently of the quark mass.Comment: To appear in Phys. Rev.
FS Aur - a new class of Cataclysmic Variables or the missing link between Intermediate Polars and SW Sex objects?
FS Aur is a known dwarf nova with an orbital period of about 85.7 minutes. It
has been assumed to be a member of the SU UMa subclass of cataclysmic variables
(CVs), but previous searches for superhumps and superoutburst have been
unsuccessful. We conducted a series of photometric and spectroscopic
observations of FS Aur during quiescence. We confirmed its short orbital period
from radial velocity measurements. However, the long-term photometry revealed
an unexpected result: the system also shows a distinct 0.24 mag modulation in
the BVR photometric bands with a period of 205.5 min, which is 2.4 times longer
than the orbital period. We discuss various possible causes for such a peculiar
behavior.Comment: 12 pages, 1 table, 12 figures, accepted for publication in PAS
Tests of model of color reconnection and a search for glueballs using gluon jets with a rapidity gap
Gluon jets with a mean energy of 22 GeV and purity of 95% are selected from
hadronic Z0 decay events produced in e+e- annihilations. A subsample of these
jets is identified which exhibits a large gap in the rapidity distribution of
particles within the jet. After imposing the requirement of a rapidity gap, the
gluon jet purity is 86%. These jets are observed to demonstrate a high degree
of sensitivity to the presence of color reconnection, i.e. higher order QCD
processes affecting the underlying color structure. We use our data to test
three QCD models which include a simulation of color reconnection: one in the
Ariadne Monte Carlo, one in the Herwig Monte Carlo, and the other by Rathsman
in the Pythia Monte Carlo. We find the Rathsman and Ariadne color reconnection
models can describe our gluon jet measurements only if very large values are
used for the cutoff parameters which serve to terminate the parton showers, and
that the description of inclusive Z0 data is significantly degraded in this
case. We conclude that color reconnection as implemented by these two models is
disfavored. The signal from the Herwig color reconnection model is less clear
and we do not obtain a definite conclusion concerning this model. In a separate
study, we follow recent theoretical suggestions and search for glueball-like
objects in the leading part of the gluon jets. No clear evidence is observed
for these objects.Comment: 42 pages, 18 figure
A study of charm production in beauty decays with the OPAL detector at LEP
Using an inclusive method, BR(b -> D\bar{D}X) has been measured in hadronic
Z^0 decays with the OPAL detector at LEP. The impact parameter significance of
tracks opposite tagged b-jets is used to differentiate b -> D\bar{D}X decays
from other decays. Using this result, the average number of charm and
anti-charm quarks produced per beauty quark decay, n_c, is determined.Comment: 20 pages, 4 figure
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