43,984 research outputs found
Money and capital as competing media of exchange in a news economy
Conventional theory suggests that fiat money will have value in capital-poor economies. We demonstrate that fiat money may also have value in capital-rich economies, if the price of capital is excessively volatile. Excess asset-price volatility is generated by news; information that has no social value, but is privately useful in forming forecasts over the short-run return to capital. One advantage of fiat money is that its expected return is not linked directly to news concerning the prospects of an underlying asset. When money and capital compete as media of exchange, excess volatility in the short-term returns of liquid asset portfolios is mitigated and welfare is improved. A legal restriction that prohibits the use of capital as a payment instrument renders the expected return to money perfectly stable and, as a consequence, may generate an additional welfare benefit.Money theory ; Capital
Blocking Java Applets at the Firewall
This paper explores the problem of protecting a site on the Internet against hostile external Java applets while allowing trusted internal applets to run. With careful implementation, a site can be made resistant to current Java security weaknesses as well as those yet to be discovered. In addition, we describe a new attack on certain sophisticated firewalls that is most effectively realized as a Java applet
Planets Transiting Non-Eclipsing Binaries
The majority of binary stars do not eclipse. Current searches for transiting
circumbinary planets concentrate on eclipsing binaries, and are therefore
restricted to a small fraction of potential hosts. We investigate the concept
of finding planets transiting non-eclipsing binaries, whose geometry would
require mutually inclined planes. Using an N-body code we explore how the
number and sequence of transits vary as functions of observing time and orbital
parameters. The concept is then generalised thanks to a suite of simulated
circumbinary systems. Binaries are constructed from RV surveys of the solar
neighbourhood. They are then populated with orbiting gas giants, drawn from a
range of distributions. The binary population is shown to be compatible with
the Kepler eclipsing binary catalogue, indicating that the properties of
binaries may be as universal as the initial mass function. These synthetic
systems produce transiting circumbinary planets occurring on both eclipsing and
non-eclipsing binaries. Simulated planets transiting eclipsing binaries are
compared with published Kepler detections. We obtain 1) that planets transiting
non-eclipsing binaries probably exist in the Kepler data, 2) that observational
biases alone cannot account for the observed over-density of circumbinary
planets near the stability limit, implying a physical pile-up, and 3) that the
distributions of gas giants orbiting single and binary stars are likely
different. Estimating the frequency of circumbinary planets is degenerate with
the spread in mutual inclination. Only a minimum occurrence rate can be
produced, which we find to be compatible with 9%. Searching for inclined
circumbinary planets may significantly increase the population of known objects
and will test our conclusions. Their existence, or absence, will reveal the
true occurrence rate and help develop circumbinary planet formation theories.Comment: 19 pages, 14 figures, accepted August 2014 to A&A, minor changes to
previous arXiv versio
Second order phase dispersion by optimised rotation pulses
We show that the duration of broadband universal control pulses can be halved
by choosing control targets with a quadratic function of phase dispersion. This
class of control pulses perform a broadband universal rotation around an axis,
in the Bloch sphere representation of two-level systems, given by this phase
dispersion function. We present an effective optimal control method to avoid
the problem of convergence to local extrema traps.Comment: 8 pages, 4 figure
Renormalization factor and effective mass of the two-dimensional electron gas
We calculate the momentum distribution of the Fermi liquid phase of the
homogeneous, two-dimensional electron gas. We show that, close to the Fermi
surface, the momentum distribution of a finite system with electrons
approaches its thermodynamic limit slowly, with leading order corrections
scaling as . These corrections dominate the extrapolation of the
renormalization factor, , and the single particle effective mass, , to
the infinite system size. We show how convergence can be improved analytically.
In the range , we get a lower renormalization factor and
a higher effective mass, , compared to the perturbative RPA values.Comment: 4 pages, 3 figure
Market Bubbles and Wasteful Avoidance: Tax and Regulatory Constraints on Short Sales
Although short sales make an important contribution to financial markets, this transaction faces legal constraints that do not govern long positions. In evaluating these constraints, other commentators, who are virtually all economists, have not focused rigorously enough on the precise contours of current law. Some short sale constraints are mischaracterized, while others are omitted entirely. Likewise, the existing literature neglects many strategies in which well advised investors circumvent these constraints; this avoidance may reduce the impact of short sale constraints on market prices, but may contribute to social waste in other ways. To fill these gaps in the literature, this paper offers a careful look at current law and draws three conclusions. First, short sales play a valuable role in the financial markets; while there may be plausible reasons to regulate short sales-- most notably, concerns about market manipulation and panics -- current law is very poorly tailored to these goals. Second, investor self-help can ease some of the harm from this poor tailoring, but at a cost. Third, relatively straightforward reforms can eliminate the need for self-help while accommodating legitimate regulatory goals. In making these points, we focus primarily on a burden that other commentators have neglected: profits from short sales generally are ineligible for the reduced tax rate on long-term capital gains, even if the short sale is in place for more than one year.Short sales, Momentum traders, Value investors
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