36,135 research outputs found
The Principles of Exchange Rate Determination in an International Finance Experiment
This paper reports the first experiments designed to explore the behavior of economies with prominent features of international finance. Two “countries,” each with its own currency, were created. International trade could take place only through the operation of markets for currency. The law of one price and the flow of funds theory of exchange rate determination were used to produce general equilibrium models that captured much of the behavior of the economies. Prices of goods, as well as the exchange rate, evolve over time toward the predictions of the models. However, both the law of one price and purchasing power parity can be rejected for reasons that do not appear in the literature. Patterns of international trade were as predicted by the law of comparative advantage
Microlensing of Lensed Supernovae
Given the number of recently discovered galaxy-galaxy lens systems, we
anticipate that a gravitationally lensed supernova will be observed within the
next few years. We explore the possibility that stars in the lens galaxy will
produce observable microlensing fluctuations in lensed supernova light curves.
For typical parameters, we predict that ~70% of lensed SNe will show
microlensing fluctuations > 0.5 mag, while ~25% will have fluctuations > 1 mag.
Thus microlensing of lensed supernova will be both ubiquitous and observable.
Additionally, we show that microlensing fluctuations will complicate
measurements of time delays from multiply imaged supernovae: time delays
accurate to better than a few days will be difficult to obtain. We also
consider prospects for extracting the lens galaxy's stellar mass fraction and
mass function from microlensing fluctuations via a new statistical measure, the
time-weighted light curve derivative.Comment: 13 pages, emulateapj format; accepted in ApJ; expanded discussion of
time delay uncertaintie
Large Scale Inhomogeneity Versus Source Evolution -- Can We Distinguish Them Observationally?
We reconsider the issue of proving large scale spatial homogeneity of the
universe, given isotropic observations about us and the possibility of source
evolution both in numbers and luminosities. Two theorems make precise the
freedom available in constructing cosmological models that will fit the
observations. They make quite clear that homogeneity cannot be proven without
either a fully determinate theory of source evolution, or availability of
distance measures that are independent of source evolution. We contrast this
goal with the standard approach that assumes spatial homogeneity a priori, and
determines source evolution functions on the basis of this assumption.Comment: mn style, mn.sty file included, mn.sty file remove
Separator development for a heat sterilizable battery Quarterly report, 1 Oct. - 31 Dec. 1966
Composite separator production for heat sterilizable silver-zinc batterie
Employer Learning and the Signaling Value of Education
If profit maximizing firms have limited information about the general productivity of new workers, they may choose to use easily observable characteristics such as years of education to 'statistically discriminate' among workers. The pure credential value of education will depend on how quickly firms learn. To obtain information on employer learning, we work with a wage equation that contains both the interaction between experience and a hard-to-observe variable that is positively related to productivity and the interaction between experience and a variable that firms can easily observe, such as years of education. The time path of the coefficient on the unobservable productivity variable provides information about the rate at which employers learn about worker productivity. Using data from the NLSY we obtain preliminary estimates of the rate at which employers learn about worker quality and use these, along with some strong auxiliary assumptions, to explore the empirical relevance of the educational screening hypothesis. We show that even if employers learn relatively slowly about the productivity of new workers, the portion of the return to education that could reflect signaling of ability is limited.
Classical Signature Change in the Black Hole Topology
Investigations of classical signature change have generally envisaged
applications to cosmological models, usually a
Friedmann-Lemaitre-Robertson-Walker model. The purpose has been to avoid the
inevitable singularity of models with purely Lorentzian signature, replacing
the neighbourhood of the big bang with an initial, singularity free region of
Euclidean signture, and a signature change. We here show that signature change
can also avoid the singularity of gravitational collapse. We investigate the
process of re-birth of Schwarzschild type black holes, modelling it as a double
signature change, joining two universes of Lorentzian signature through a
Euclidean region which provides a `bounce'. We show that this process is viable
both with and without matter present, but realistic models -- which have the
signature change surfaces hidden inside the horizons -- require non-zero
density. In fact the most realistic models are those that start as a finite
cloud of collapsing matter, surrounded by vacuum. We consider how geodesics may
be matched across a signature change surface, and conclude that the particle
`masses' must jump in value. This scenario may be relevant to Smolin's recent
proposal that a form of natural selection operates on the level of universes,
which favours the type of universe we live in.Comment: LaTeX, 19 pages, 11 Figures. Replacement - only change is following
comment: For a pdf version with the figures embedded, see
http://www.mth.uct.ac.za/~cwh/mypub.htm
Separator development for a heat sterilizable battery Quarterly report, 1 Jun. - 30 Sep. 1966
Filler and matrix composite materials for use in silver-zinc battery separator
Recommended from our members
Analysis of the visual spatiotemporal properties of American Sign Language.
Careful measurements of the temporal dynamics of speech have provided important insights into phonetic properties of spoken languages, which are important for understanding auditory perception. By contrast, analytic quantification of the visual properties of signed languages is still largely uncharted. Exposure to sign language is a unique experience that could shape and modify low-level visual processing for those who use it regularly (i.e., what we refer to as the Enhanced Exposure Hypothesis). The purpose of the current study was to characterize the visual spatiotemporal properties of American Sign Language (ASL) so that future studies can test the enhanced exposure hypothesis in signers, with the prediction that altered vision should be observed within, more so than outside, the range of properties found in ASL. Using an ultrasonic motion tracking system, we recorded the hand position in 3-dimensional space over time during sign language production of signs, sentences, and narratives. From these data, we calculated several metrics: hand position and eccentricity in space and hand motion speed. For individual signs, we also measured total distance travelled by the dominant hand and total duration of each sign. These metrics were found to fall within a selective range, suggesting that exposure to signs is a specific and unique visual experience, which might alter visual perceptual abilities in signers for visual information within the experienced range, even for non-language stimuli
A Program for the Collection, Storage, and Analysis of Baseline Environmental Data for Cook Inlet, Alaska
The scope of this report is to provide a general, yet comprehensive,
description of the Cook Inlet System which will serve as a
basis for understanding the interrelated natural and man-made factors
governing its future; to present a program of field research studies
for the estuarine environment that will describe the existing state of
the Inlet with respect to the water quality and biota; to provide a
framework whereby the program of studies can be evaluated and redirected
in light of the preliminary results; and, to provide a method of storing
and analyzing the data from the investigations so that it can be made
available to interested parties in the most efficient manner possible.This report was prepared by the Institute of Water Resources of the
University of Alaska for the Alaska Water Laboratory, Federal Water
Pollution Control Administration under Contract No. 14-12-449
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