4,917 research outputs found
Investigating people: a qualitative analysis of the search behaviours of open-source intelligence analysts
The Internet and the World Wide Web have become integral parts of the lives of many modern individuals, enabling almost instantaneous communication, sharing and broadcasting of thoughts, feelings and opinions. Much of this information is publicly facing, and as such, it can be utilised in a multitude of online investigations, ranging from employee vetting and credit checking to counter-terrorism and fraud prevention/detection. However, the search needs and behaviours of these investigators are not well documented in the literature. In order to address this gap, an in-depth qualitative study was carried out in cooperation with a leading investigation company. The research contribution is an initial identification of Open-Source Intelligence investigator search behaviours, the procedures and practices that they undertake, along with an overview of the difficulties and challenges that they encounter as part of their domain. This lays the foundation for future research in to the varied domain of Open-Source Intelligence gathering
Non-Perturbative One-Loop Effective Action for Electrodynamics in Curved Spacetime
In this paper we explicitly evaluate the one-loop effective action in four
dimensions for scalar and spinor fields under the influence of a strong,
covariantly constant, magnetic field in curved spacetime. In the framework of
zeta function regularization, we find the one-loop effective action to all
orders in the magnetic field up to linear terms in the Riemannian curvature. As
a particular case, we also obtain the one-loop effective action for massless
scalar and spinor fields. In this setting, we found that the vacuum energy of
charged spinors with small mass becomes very large due entirely by the
gravitational correction.Comment: LaTeX, 23 page
Exact Site Percolation Thresholds Using the Site-to-Bond and Star-Triangle Transformations
I construct a two-dimensional lattice on which the inhomogeneous site
percolation threshold is exactly calculable and use this result to find two
more lattices on which the site thresholds can be determined. The primary
lattice studied here, the ``martini lattice'', is a hexagonal lattice with
every second site transformed into a triangle. The site threshold of this
lattice is found to be , while the others have and
. This last solution suggests a possible approach to establishing
the bound for the hexagonal site threshold, . To derive these
results, I solve a correlated bond problem on the hexagonal lattice by use of
the star-triangle transformation and then, by a particular choice of
correlations, solve the site problem on the martini lattice.Comment: 12 pages, 10 figures. Submitted to Physical Review
Acute military psychiatric casualties from the war in Iraq
Background: The view that most military personnel evacuated from war zones are suffering from combat stress reactions, or are otherwise traumatised by the horrors of war, has an impact on all aspects of military psychiatry.
Aims: To delineate the reasons for psychiatric aeromedical evacuation from Iraq from the start of build-up of UK forces in January 2003 until the end of October that year, 6 months after the end of formal hostilities.
Method: A retrospective study was conducted of field and in-patient psychiatric assessments of 116 military personnel evacuated to the UK military psychiatric in-patient facility in Catterick Garrison.
Results: Evacuees were mainly non-combatants (69%). A significant proportion were in reserve service (21%) and had a history of contact with mental health services (37%). Only 3% had a combat stress reaction. In over 85% of cases evacuation was for low mood attributed to separation from friends or family, or difficulties adjusting to the environment.
Conclusions: These findings have implications especially for screening for suitability for deployment, and for understanding any longer-term mental health problems arising in veterans from Iraq
Collective states of interacting non-Abelian anyons
We study the finite size spectrum of integrable quantum chains of interacting
non-Abelian anyons constructed using the Drinfeld double of the dihedral group
. The gapless low energy modes are identified as the direct product of two
conformal field theories which can be decomposed according to the residual
symmetries of the chains subject to periodic boundary conditions.Comment: 11 page
Spacetime geometry of static fluid spheres
We exhibit a simple and explicit formula for the metric of an arbitrary
static spherically symmetric perfect fluid spacetime. This class of metrics
depends on one freely specifiable monotone non-increasing generating function.
We also investigate various regularity conditions, and the constraints they
impose. Because we never make any assumptions as to the nature (or even the
existence) of an equation of state, this technique is useful in situations
where the equation of state is for whatever reason uncertain or unknown.
To illustrate the power of the method we exhibit a new form of the
``Goldman--I'' exact solution and calculate its total mass. This is a
three-parameter closed-form exact solution given in terms of algebraic
combinations of quadratics. It interpolates between (and thereby unifies) at
least six other reasonably well-known exact solutions.Comment: Plain LaTeX 2e -- V2: now 22 pages; minor presentation changes in the
first part of the paper -- no physics modifications; major additions to the
examples section: the Gold-I solution is shown to be identical to the G-G
solution. The interior Schwarzschild, Stewart, Buch5 XIII, de Sitter, anti-de
Sitter, and Einstein solutions are all special cases. V3: Reference,
footnotes, and acknowledgments added, typos fixed -- no physics
modifications. V4: Technical problems with mass formula fixed -- affects
discussion of our examples but not the core of the paper. Version to appear
in Classical and Quantum Gravit
A industrialização do álcool brasileiro em usinas de pequena escala de produção: uma avaliação econômica.
bitstream/item/45723/1/Industrializacao-alcool.pd
Magnetized strangelets at finite temperature
The main properties of magnetized strangelets, namely, their energy per
baryon, radius and electric charge, are studied. Temperature effects are also
taken into account in order to study their stability compared to the 56Fe
isotope and non-magnetized strangelets using the liquid drop model. Massive
quarks are considered with the aim to have a more realistic description for
strangelets in the astrophysical context and the environment of heavy ion
colliders, playing also an important role in the thermodynamical quantities of
the quark gas. It is concluded that the presence of a magnetic field tends to
stabilize more the strangelets, even when temperature effects are taken into
account. Magnetized strangelets in a paired superconductor phase (magnetized
color flavor locked phase) are also discussed. It is shown that they are more
stable than ordinary magnetized strangelets for typical gap values of the order
of O(100) MeV.Comment: 10 pages, 10 figures, discussion extended, new references adde
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