25,404 research outputs found
Foreign Direct Investment, Exchange Rate Variability and Demand Uncertainty
Variable real exchange rates influence the country choice for location of production facilities by a multinational enterprise. With risk averse investors and fixed productive factors, a parent company should not be indifferent to the choice of production capacity location, even when the expected costs of production are identical across countries. If a non-negative correlation exists between real export demand shocks and real exchange rate shocks, the multinational will optimally locate some of its productive capacity abroad. The share of production capacity optimally located abroad increases as exchange rate volatility rises and as export demand shocks become more correlated. These theoretical results are confirmed by empirical analysis of quarterly United States bilateral foreign-direct- investment flows with Canada, Japan, and the United Kingdom.
Prevent: what is pre-criminal space?
Prevent is a UK-wide programme within the governmentâs anti-terrorism strategy aimed at stopping individuals from supporting or taking part in terrorist activities. NHS Englandâs Prevent Training and Competencies Framework requires health professionals to understand the concept of pre-criminal space. This article examines pre-criminal space, a new term which refers to a period of time during which a person is referred to a specific Prevent-related safeguarding panel, Channel. It is unclear what the concept of pre-criminal space adds to the Prevent programme. The term should be either clarified or removed from the Framework
Learning Convex Partitions and Computing Game-theoretic Equilibria from Best Response Queries
Suppose that an -simplex is partitioned into convex regions having
disjoint interiors and distinct labels, and we may learn the label of any point
by querying it. The learning objective is to know, for any point in the
simplex, a label that occurs within some distance from that point.
We present two algorithms for this task: Constant-Dimension Generalised Binary
Search (CD-GBS), which for constant uses queries, and Constant-Region Generalised Binary
Search (CR-GBS), which uses CD-GBS as a subroutine and for constant uses
queries.
We show via Kakutani's fixed-point theorem that these algorithms provide
bounds on the best-response query complexity of computing approximate
well-supported equilibria of bimatrix games in which one of the players has a
constant number of pure strategies. We also partially extend our results to
games with multiple players, establishing further query complexity bounds for
computing approximate well-supported equilibria in this setting.Comment: 38 pages, 7 figures, second version strengthens lower bound in
Theorem 6, adds footnotes with additional comments and fixes typo
Hydrogen and fluorine in the surfaces of lunar samples
The resonant nuclear reaction F-19 (p, alpha gamma)0-16 has been used to perform depth sensitive analyses for both fluorine and hydrogen in lunar samples. The resonance at 0.83 MeV (center-of-mass) in this reaction has been applied to the measurement of the distribution of trapped solar protons in lunar samples to depths of about 1/2 micrometer. These results are interpreted in terms of terrestrial H2O surface contamination and a redistribution of the implanted solar H which has been influenced by heavy radiation damage in the surface region. Results are also presented for an experiment to test the penetration of H2O into laboratory glass samples which have been irradiated with 0-16 to simulate the radiation damaged surfaces of lunar glasses. Fluorine determinations have been performed in a 1 pm surface layer on lunar samples using the same F-19 alpha gamma)0-16 resonance. The data are discussed from the standpoint of lunar fluorine and Teflon contamination
A New Approach to Black Hole Microstates
If one encodes the gravitational degrees of freedom in an orthonormal frame
field there is a very natural first order action one can write down (which in
four dimensions is known as the Goldberg action). In this essay we will show
that this action contains a boundary action for certain microscopic degrees of
freedom living at the horizon of a black hole, and argue that these degrees of
freedom hold great promise for explaining the microstates responsible for black
hole entropy, in any number of spacetime dimensions. This approach faces many
interesting challenges, both technical and conceptual.Comment: 6 pages, 0 figures, LaTeX; submitted to Mod. Phys. Lett. A.; this
essay received "honorable mention" from the Gravity Research Foundation, 199
Relativistic three-body recombination with the QED vacuum
Electron-positron pair annihilation into a single photon is studied when a
second free electron is present. Focussing on the relativistic regime, we show
that the photon emitted in the three-lepton interaction may exhibit distinct
angular distributions and polarization properties. Moreover, the process can
dominate over two-photon annihilation in relativistic electron-positron plasmas
of few-MeV temperature. An analogy with three-body recombination of electrons
with ions is drawn.Comment: 5 pages, 4 figure
The Spin Holonomy Group In General Relativity
It has recently been shown by Goldberg et al that the holonomy group of the
chiral spin-connection is preserved under time evolution in vacuum general
relativity. Here, the underlying reason for the time-independence of the
holonomy group is traced to the self-duality of the curvature 2-form for an
Einstein space. This observation reveals that the holonomy group is
time-independent not only in vacuum, but also in the presence of a cosmological
constant. It also shows that once matter is coupled to gravity, the
"conservation of holonomy" is lost. When the fundamental group of space is
non-trivial, the holonomy group need not be connected. For each homotopy class
of loops, the holonomies comprise a coset of the full holonomy group modulo its
connected component. These cosets are also time-independent. All possible
holonomy groups that can arise are classified, and examples are given of
connections with these holonomy groups. The classification of local and global
solutions with given holonomy groups is discussed.Comment: 21 page
Multiobjective analysis for the design and control of an electromagnetic valve actuator
The electromagnetic valve actuator can deliver much improved fuel efficiency and reduced emissions in spark ignition (SI) engines owing to the potential for variable valve timing when compared with cam-operated, or conventional, variable valve strategies. The possibility exists to reduce pumping losses by throttle-free operation, along with closed-valve engine braking. However, further development is required to make the technology suitable for accept- ance into the mass production market. This paper investigates the application of multiobjective optimization techniques to the conflicting objective functions inherent in the operation of such a device. The techniques are utilized to derive the optimal forceâdisplacement characteristic for the solenoid actuator, along with its controllability and dynamic/steady state performance
Proof of principle of a high-spatial-resolution, resonant-response gamma-ray detector for Gamma Resonance Absorption in 14N
The development of a mm-spatial-resolution, resonant-response detector based
on a micrometric glass capillary array filled with liquid scintillator is
described. This detector was developed for Gamma Resonance Absorption (GRA) in
14N. GRA is an automatic-decision radiographic screening technique that
combines high radiation penetration (the probe is a 9.17 MeV gamma ray) with
very good sensitivity and specificity to nitrogenous explosives. Detailed
simulation of the detector response to electrons and protons generated by the
9.17 MeV gamma-rays was followed by a proof-of-principle experiment, using a
mixed gamma-ray and neutron source. Towards this, a prototype capillary
detector was assembled, including the associated filling and readout systems.
Simulations and experimental results indeed show that proton tracks are
distinguishable from electron tracks at relevant energies, on the basis of a
criterion that combines track length and light intensity per unit length.Comment: 18 pages, 16 figure
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