41,284 research outputs found
Finite temperature analytical results for a harmonically confined gas obeying exclusion statistics in -dimensions
Closed form, analytical results for the finite-temperature one-body density
matrix, and Wigner function of a -dimensional, harmonically trapped gas of
particles obeying exclusion statistics are presented. As an application of our
general expressions, we consider the intermediate particle statistics arising
from the Gentile statistics, and compare its thermodynamic properties to the
Haldane fractional exclusion statistics. At low temperatures, the thermodynamic
quantities derived from both distributions are shown to be in excellent
agreement. As the temperature is increased, the Gentile distribution continues
to provide a good description of the system, with deviations only arising well
outside of the degenerate regime. Our results illustrate that the exceedingly
simple functional form of the Gentile distribution is an excellent alternative
to the generally only implicit form of the Haldane distribution at low
temperatures.Comment: 17 pages, 2 eps figure
Citizenship, community, and counter-terrorism : UK security discourse, 2001-2011
This paper analyses a corpus of UK policy documents which sets out national security policy as an exemplar of the contemporary discourse of counter-terrorism in Europe, the USA and worldwide. A corpus of 148 documents (c. 2.8 million words) was assembled to reflect the security discourse produced by the UK government before and after the 7/7 attacks on the London Transport system. To enable a chronological comparison, the two sub-corpora were defined: one relating to a discourse of citizenship and community cohesion (2001-2006); and one relating to the ‘Preventing Violent Extremism’ discourse (2007-2011). Wordsmith Tools (Scott 2008) was used to investigate keywords and patterns of collocation. The results present
themes emerging from a comparative analysis of the 100 strongest keywords in each sub- corpus; as well as a qualitative analysis of related patterns of the collocation, focusing inparticular on features of connotation and semantic prosody
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On the use of photobleaching to reduce fluorescence background in Raman spectroscopy to improve the reliability of pigment identification on painted textiles
Subjecting a specimen of red lead watercolour paint on silk to photobleaching was demonstrated to be a simple means by which to engineer a reduction in the magnitude of the fluorescent background that was approximately exponential with time, with a corresponding improvement in the signal to noise ratio of the Raman spectrum, thus rendering the characteristic peaks more easily visible and allowing more confident identification of the pigment. However, relative heights of the Raman peaks obtained from the sample were seen to alter progressively as a result of irradiation, indicating that some component of the sample was undergoing degradation that may result in longer-term damage to a fragile historic artefact. It was also shown that crystals of the lead monoxide pigment massicot were present in the samples ofred lead on a painted silk artefact dating from 1750. It is concluded that this was either due to deliberate mixing of pigments by the artist, contrary to historic records, or as a result of the roasting techniques used to create red lead pigments at the time and not due to thermal degradation of the pigment during Raman analysis
Developments in the tools and methodologies of synthetic biology.
Synthetic biology is principally concerned with the rational design and engineering of biologically based parts, devices, or systems. However, biological systems are generally complex and unpredictable, and are therefore, intrinsically difficult to engineer. In order to address these fundamental challenges, synthetic biology is aiming to unify a body of knowledge from several foundational scientific fields, within the context of a set of engineering principles. This shift in perspective is enabling synthetic biologists to address complexity, such that robust biological systems can be designed, assembled, and tested as part of a biological design cycle. The design cycle takes a forward-design approach in which a biological system is specified, modeled, analyzed, assembled, and its functionality tested. At each stage of the design cycle, an expanding repertoire of tools is being developed. In this review, we highlight several of these tools in terms of their applications and benefits to the synthetic biology community
Vortex Lattice Structure of Fulde-Ferrell-Larkin-Ovchinnikov Superconductors
In superconductors with singlet pairing, the inhomogeneous
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is expected to be stabilized by a
large Zeeman splitting. We develop an efficient method to evaluate the
Landau-Ginzburg free energies of FFLO-state vortex lattices and use it to
simplify the considerations that determine the optimal vortex configuration at
different points in the phasediagram. We demonstrate that the order parameter
spatial profile is completely determined, up to a uniform translation, by its
Landau level index n and the vortex Lattice structure and derive an explicit
expression for the order parameter spatial profile that can be used to
determine n from experimental data.Comment: 6 pages with one embedded color figure. Minor changes. Final version
as publishe
The ALFALFA HI Absorption Pilot Survey: A Wide-Area Blind Damped Lyman Alpha System Survey of the Local Universe
We present the results of a pilot survey for neutral hydrogen (HI) 21 cm
absorption in the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA)
Survey. This project is a wide-area "blind" search for HI absorption in the
local universe, spanning -650 km/s < cz < 17,500 km/s and covering 517.0 square
degrees (7% of the full ALFALFA survey). The survey is sensitive to HI
absorption lines stronger than 7.7 mJy (8983 radio sources) and is 90% complete
for lines stronger than 11.0 mJy (7296 sources). The total redshift interval
sensitive to all damped Lyman alpha (DLA) systems (N_HI >= 2x10^20 cm^-2) is
Delta z = 7.0 (129 objects, assuming T_s = 100 K and covering fraction unity);
for super-DLAs (N_HI >= 2x10^21 cm^-2) it is Delta z= 128.2 (2353 objects). We
re-detect the intrinsic HI absorption line in UGC 6081 but detect no
intervening absorption line systems. We compute a 95% confidence upper limit on
the column density frequency distribution function f(N_HI,X) spanning four
orders of magnitude in column density, 10^19 (T_s/100 K)(1/f) cm^-2 < N_HI <
10^23 (T_s/100 K)(1/f) cm^-2, that is consistent with previous redshifted
optical damped Ly alpha surveys and the aggregate HI 21 cm emission in the
local universe. The detection rate is in agreement with extant observations.
This pilot survey suggests that an absorption line search of the complete
ALFALFA survey --- or any higher redshift, larger bandwidth, or more sensitive
survey, such as those planned for Square Kilometer Array pathfinders or a low
frequency lunar array --- will either make numerous detections or will set a
strong statistical lower limit on the typical spin temperature of neutral
hydrogen gas.Comment: 7 pages, 7 figures, accepted by Ap
The Zel'dovich effect in harmonically trapped, ultra-cold quantum gases
We investigate the Zel'dovich effect in the context of ultra-cold,
harmonically trapped quantum gases. We suggest that currently available
experimental techniques in cold-atoms research offer an exciting opportunity
for a direct observation of the Zel'dovich effect without the difficulties
imposed by conventional condensed matter and nuclear physics studies. We also
demonstrate an interesting scaling symmetry in the level rearragements which
has heretofore gone unnoticed
The Global Dimension to Fiscal Sustainability
This paper examines the issue of fiscal sustainability in emerging market countries and industrial countries. We highlight the importance of the time series properties of the primary surplus and debt, and find evidence of a positive long run relationship. Consequently we emphasise, that especially for emerging markets, it is important to recognise the implications of global capital market shocks for fiscal sustainability, a relationship which has hitherto been ignored in the empirical literature. Using a factor model we demonstrate that the relationship between deficit and debt is conditional upon a global factor and we suggest that this global factor is related to worldwide liquidity. We also demonstrate that this acts as a constraint on emerging market economies’ fiscal policy.Fiscal Policy; Sustainability.
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