33,827 research outputs found
A U.S. Manager\u27s Guide to Differences Between IFRS and U.S. GAAP
International Financial Reporting Standards (IFRS) are now required for consolidated financial reports for all European Union exchange-listed companies. Officials estimated that for 2005, the initial year of EU adoption, 8,000 financial statements were prepared in accordance with IFRS for the first time. Other countries have also adopted IFRS or IFRS-equivalent financial reporting standards. IFRS differ from U.S. Generally Accepted Accounting Principles (GAAP) in many key areas. The International Accounting Standards Board (IASB) and the Financial Accounting Standards Board (FASB) are working on various convergence projects designed to reduce or eliminate differences between the two sets of reporting standards. But existing differences will likely continue for at least the next two years, and, for many accounting topics, differences are likely to last much longer. This article highlights the 20 convergence projects and summarizes the differences between the two sets of standards. In addition, differences in three topics that are not included in the convergence efforts are identified. Differences between IFRS and U.S. GAAP found in actual EU company Form 20-F filings are used to illustrate the impact of the reporting-standard differences
Stochastic Ergodicity Breaking: a Random Walk Approach
The continuous time random walk (CTRW) model exhibits a non-ergodic phase
when the average waiting time diverges. Using an analytical approach for the
non-biased and the uniformly biased CTRWs, and numerical simulations for the
CTRW in a potential field, we obtain the non-ergodic properties of the random
walk which show strong deviations from Boltzmann--Gibbs theory. We derive the
distribution function of occupation times in a bounded region of space which,
in the ergodic phase recovers the Boltzmann--Gibbs theory, while in the
non-ergodic phase yields a generalized non-ergodic statistical law.Comment: 5 pages, 3 figure
Simulations for trapping reactions with subdiffusive traps and subdiffusive particles
While there are many well-known and extensively tested results involving
diffusion-limited binary reactions, reactions involving subdiffusive reactant
species are far less understood. Subdiffusive motion is characterized by a mean
square displacement with . Recently we
calculated the asymptotic survival probability of a (sub)diffusive
particle () surrounded by (sub)diffusive traps () in one
dimension. These are among the few known results for reactions involving
species characterized by different anomalous exponents. Our results were
obtained by bounding, above and below, the exact survival probability by two
other probabilities that are asymptotically identical (except when
and ). Using this approach, we were not able to
estimate the time of validity of the asymptotic result, nor the way in which
the survival probability approaches this regime. Toward this goal, here we
present a detailed comparison of the asymptotic results with numerical
simulations. In some parameter ranges the asymptotic theory describes the
simulation results very well even for relatively short times. However, in other
regimes more time is required for the simulation results to approach asymptotic
behavior, and we arrive at situations where we are not able to reach asymptotia
within our computational means. This is regrettably the case for
and , where we are therefore not able to prove
or disprove even conjectures about the asymptotic survival probability of the
particle.Comment: 15 pages, 10 figures, submitted to Journal of Physics: Condensed
Matter; special issue on Chemical Kinetics Beyond the Textbook: Fluctuations,
Many-Particle Effects and Anomalous Dynamics, eds. K.Lindenberg, G.Oshanin
and M.Tachiy
Diffusion in scale-free networks with annealed disorder
The scale-free (SF) networks that have been studied so far contained quenched
disorder generated by random dilution which does not vary with the time. In
practice, if a SF network is to represent, for example, the worldwide web, then
the links between its various nodes may temporarily be lost, and re-established
again later on. This gives rise to SF networks with annealed disorder. Even if
the disorder is quenched, it may be more realistic to generate it by a
dynamical process that is happening in the network. In this paper, we study
diffusion in SF networks with annealed disorder generated by various scenarios,
as well as in SF networks with quenched disorder which, however, is generated
by the diffusion process itself. Several quantities of the diffusion process
are computed, including the mean number of distinct sites visited, the mean
number of returns to the origin, and the mean number of connected nodes that
are accessible to the random walkers at any given time. The results including,
(1) greatly reduced growth with the time of the mean number of distinct sites
visited; (2) blocking of the random walkers; (3) the existence of a phase
diagram that separates the region in which diffusion is possible from one in
which diffusion is impossible, and (4) a transition in the structure of the
networks at which the mean number of distinct sites visited vanishes, indicate
completely different behavior for the computed quantities than those in SF
networks with quenched disorder generated by simple random dilution.Comment: 18 pages including 8 figure
Three-dimensional carrier-dynamics simulation of terahertz emission from photoconductive switches
A semi-classical Monte Carlo model for studying three-dimensional carrier
dynamics in photoconductive switches is presented. The model was used to
simulate the process of photoexcitation in GaAs-based photoconductive antennas
illuminated with pulses typical of mode-locked Ti:Sapphire lasers. We analyzed
the power and frequency bandwidth of THz radiation emitted from these devices
as a function of bias voltage, pump pulse duration and pump pulse location. We
show that the mechanisms limiting the THz power emitted from photoconductive
switches fall into two regimes: when illuminated with short duration (<40 fs)
laser pulses the energy distribution of the Gaussian pulses constrains the
emitted power, while for long (>40 fs) pulses, screening is the primary
power-limiting mechanism. A discussion of the dynamics of bias field screening
in the gap region is presented. The emitted terahertz power was found to be
enhanced when the exciting laser pulse was in close proximity to the anode of
the photoconductive emitter, in agreement with experimental results. We show
that this enhancement arises from the electric field distribution within the
emitter combined with a difference in the mobilities of electrons and holes.Comment: 7 pages, 7 figure
Experimental Verification of Surface Vehicle Dynamics
Experimental verification of surface vehicle dynamic
Using a Grid-Enabled Wireless Sensor Network for Flood Management
Flooding is becoming an increasing problem. As a result there is a need to deploy more sophisticated sensor networks to detect and react to flooding. This paper outlines a demonstration that illustrates our proposed solution to this problem involving embedded wireless hardware, component based middleware and overlay networks
Finite-element analysis of contact between elastic self-affine surfaces
Finite element methods are used to study non-adhesive, frictionless contact
between elastic solids with self-affine surfaces. We find that the total
contact area rises linearly with load at small loads. The mean pressure in the
contact regions is independent of load and proportional to the rms slope of the
surface. The constant of proportionality is nearly independent of Poisson ratio
and roughness exponent and lies between previous analytic predictions. The
contact morphology is also analyzed. Connected contact regions have a fractal
area and perimeter. The probability of finding a cluster of area drops as
where increases with decreasing roughness exponent. The
distribution of pressures shows an exponential tail that is also found in many
jammed systems. These results are contrasted to simpler models and experiment.Comment: 13 pages, 15 figures. Replaced after changed in response to referee
comments. Final two figures change
First exit times and residence times for discrete random walks on finite lattices
In this paper, we derive explicit formulas for the surface averaged first
exit time of a discrete random walk on a finite lattice. We consider a wide
class of random walks and lattices, including random walks in a non-trivial
potential landscape. We also compute quantities of interest for modelling
surface reactions and other dynamic processes, such as the residence time in a
subvolume, the joint residence time of several particles and the number of hits
on a reflecting surface.Comment: 19 pages, 2 figure
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