1,723 research outputs found
Corrigan-Ramond Extension of QCD at Nonzero Baryon Density
We investigate the Corrigan-Ramond extension of one massless flavor Quantum
Chromo Dynamics at nonzero quark chemical potential. Since the extension
requires the fermions to transform in the two index antisymmetric
representation of the gauge group, one finds that the number of possible
channels is richer than in the 't Hooft limit. We first discuss the diquark
channels and show that for a number of colors larger than three a new diquark
channel appears. We then study the infinite number of color limit and show that
the Fermi surface is unstable to the formation of the
Deryagin-Grigoriev-Rubakov chiral waves. We discover, differently from the 't
Hooft limit, the possibility of a colored chiral wave breaking the color
symmetry as well as translation invariance.Comment: RevTeX, 14 pages, 2 figure
The Rise and Fall of Canada\u27s Cold War Air Force, 1948-1968
This thesis examines the expansion of the Royal Canadian Air Force (RCAF) under the St. Laurent government with the concept of the Big Air Force that emerged from the defence re-armament programme announced on 5 February 1951. During this critical Cold War period, the RCAF became Canadaâs first line of defence, making an essential contribution to the collective defence of Western Europe through the North Atlantic Treaty Organization. Concurrently, the RCAF underwent tremendous expansion in Canada contributing to North American defence, along with significant increases in its training, maritime and transport capabilities. The RCAF developed into the largest military service with the biggest portion of the defence budget. The notion of âairmindednessâ that permeated all aspects of Canadian society enabled the development and implementation of the Big Air Force concept. Underlying the Big Air Force concept were two conflicting visions of air power, derived from leading theorists of the 1920s. The first was an independent role for aviation, âDouhet with nukes,â a Cold War reference to the ideas of Italian General Giulio Douhet. The second approach was American General William Mitchellâs âanything that fliesâ construct that embraced missions under the control of the army and navy and support to other agencies in such undertakings as air transport. By the late 1950s, the Big Air Force could not be sustained, thus marking its decline under the Diefenbaker and Pearson governments that was complete by the late 1960s. Despite some modernization in the late 1970s, successive governments adhered to the notion of a âminimalist air forceâ after 1969 until the end of the Cold War. This thesis considers the expansion and decline of the air force from the perspective of three inter-related thematic pillars â politics and economics, military strategy and technology. The predominance of air power represented the Canadian âway of warâ during this time, and this legacy still resonates today with the ongoing debate regarding the F-35 aircraft for the RCAFâs Next Generation Fighter Capability programme
WASP-1: A lithium- and metal-rich star with an oversized planet
In this paper we present our results of a comprehensive spectroscopicanalysis
of WASP-1, the host star to the exoplanet WASP-1b. We derive T_eff = 6110 +/-
45 K, log g = 4.28 +/- 0.15, and [M/H] = 0.23 +/- 0.08, and also a high
abundance of lithium, log n(Li) = 2.91 +/- 0.05. These parameters suggests an
age for the system of 1-3 Gyr and a stellar mass of 1.25-1.35 M_sun. This means
that WASP-1 has properties very similar to those of HD 149026, the host star
for the highest density planet yet detected. Moreover, their planets orbit at
comparable distances and receive comparable irradiating fluxes from their host
stars. However, despite the similarity of WASP-1 with HD 149026, their planets
have strongly different densities. This suggests that gas-giant planet density
is not a simple function of host-star metallicity or of radiation environment
at ages of ~2 Gyr.Comment: Accepted for publication in MNRAS. 6 pages, 4 figure
Sounding stellar cycles with Kepler - preliminary results from ground-based chromospheric activity measurements
Due to its unique long-term coverage and high photometric precision,
observations from the Kepler asteroseismic investigation will provide us with
the possibility to sound stellar cycles in a number of solar-type stars with
asteroseismology. By comparing these measurements with conventional
ground-based chromospheric activity measurements we might be able to increase
our understanding of the relation between the chromospheric changes and the
changes in the eigenmodes.
In parallel with the Kepler observations we have therefore started a
programme at the Nordic Optical Telescope to observe and monitor chromospheric
activity in the stars that are most likely to be selected for observations for
the whole satellite mission. The ground-based observations presented here can
be used both to guide the selection of the special Kepler targets and as the
first step in a monitoring programme for stellar cycles. Also, the
chromospheric activity measurements obtained from the ground-based observations
can be compared with stellar parameters such as ages and rotation in order to
improve stellar evolution models.Comment: submitted to the proceedings of the IAU symposium No. 264, 200
Variable stars in the Open Cluster M11 (NGC 6705)
V-band time-series CCD photometric observations of the intermediate-age open
cluster M11 were performed to search for variable stars. Using these
time-series data, we carefully examined light variations of all stars in the
observing field. A total of 82 variable stars were discovered, of which 39
stars had been detected recently by Hargis et al. (2005). On the basis of
observational properties such as variable period, light curve shape, and
position on a color-magnitude diagram, we classified their variable types as 11
delta Scuti-type pulsating stars, 2 gamma Doradus-type pulsating stars, 40 W
UMa-type contact eclipsing binaries, 13 Algol-type detached eclipsing binaries,
and 16 eclipsing binaries with long period. Cluster membership for each
variable star was deduced from the previous proper motion results (McNamara et
al. 1977) and position on the color-magnitude diagram. Many pulsating stars and
eclipsing binaries in the region of M11 are probable members of the cluster.Comment: 23 pages, 9 figures, 3 tables, and accepted for publication in PAS
Detection of Solar-like Oscillations in the G7 Giant Star xi Hya
We report the firm discovery of solar-like oscillations in a giant star. We
monitored the star xi Hya (G7III) continuously during one month with the
CORALIE spectrograph attached to the 1.2m Swiss Euler telescope. The 433
high-precision radial-velocity measurements clearly reveal multiple oscillation
frequencies in the range 50 - 130 uHz, corresponding to periods between 2.0 and
5.5 hours. The amplitudes of the strongest modes are slightly smaller than 2
m/s. Current model calculations are compatible with the detected modes.Comment: 4 pages, 4 figures, accepted for publication as a letter in A&
Inertial amplification of continuous structures: Large band gaps from small masses
Wave motion in a continuous elastic rod with a periodically attached
inertial-amplification mechanism is investigated. The mechanism has properties
similar to an "inerter" typically used in vehicle suspensions, however here it
is constructed and utilized in a manner that alters the intrinsic properties of
a continuous structure. The elastodynamic band structure of the hybrid
rod-mechanism structure yields band gaps that are exceedingly wide and deep
when compared to what can be obtained using standard local resonators, while
still being low in frequency. With this concept, a large band gap may be
realized with as much as twenty times less added mass compared to what is
needed in a standard local resonator configuration. The emerging inertially
enhanced continuous structure also exhibits unique qualitative features in its
dispersion curves. These include the existence of a characteristic double-peak
in the attenuation constant profile within gaps and the possibility of
coalescence of two neighbouring gaps creating a large contiguous gap.Comment: Manuscript is under review for journal publicatio
Simulations of super-structure domain walls in two dimensional assemblies of magnetic nanoparticles
We simulate the formation of domain walls in two-dimensional assemblies of magnetic nanoparticles. Particle parameters are chosen to match recent electron holography and Lorentz microscopy studies of almost monodisperse cobalt nanoparticles assembled into regular, elongated lattices. As the particles are small enough to consist of a single magnetic domain each, their magnetic interactions can be described by a spin model in which each particle is assigned a macroscopic "superspin." Thus, the magnetic behaviour of these lattices may be compared to magnetic crystals with nanoparticle superspins taking the role of the atomic spins. The coupling is, however, different. The superspins interact only by dipolar interactions as exchange coupling between individual nanoparticles may be neglected due to interparticle spacing. We observe that it is energetically favorable to introduce domain walls oriented along the long dimension of nanoparticle assemblies rather than along the short dimension. This is unlike what is typically observed in continuous magnetic materials, where the exchange interaction introduces an energetic cost proportional to the area of the domain walls. Structural disorder, which will always be present in realistic assemblies, pins longitudinal domain walls when the external field is reversed, and makes a gradual reversal of the magnetization by migration of longitudinal domain walls possible, in agreement with previous experimental results. (C) 2015 AIP Publishing LLC
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