27,959 research outputs found
How Tight is Too Tight? A Look at Welfare Implications of Distortionary Policies in Uzbekistan
Since independence in 1991, Uzbekistan has pursued a gradual approach to the transition from planned to market economy. This approach relied heavily on trade controls, directed credit, and large public investments. In addition, a number of financial sector measures were instituted that distorted resource allocation and increased transaction costs. As a result, while possibly preventing the contraction of output in the early 1990s, these policies led to disappointing economic outcomes and social conditions later on. The paper reviews the underlying distortions and presents survey-based evidence to support their existence and their detrimental impact on economic activity. Looking forward, the paper - using a representative agent framework to model existing financial sector distortions - offers some guidance regarding the likely implications of eliminating these distortions on key aggregate variables. It suggests that the elimination of these distortions will be welfare enhancing and will lead to higher levels of investment and capital stock.financial sector distortions, transition, Uzbekistan
Microlensing Surveys of M31 in the Wide Field Imaging Era
The Andromeda Galaxy (M31) is the closest large galaxy to the Milky Way, thus
it is an important laboratory for studying massive dark objects in galactic
halos (MACHOs) by gravitational microlensing. Such studies strongly complement
the studies of the Milky Way halo using the the Large and Small Magellanic
Clouds. We consider the possibilities for microlensing surveys of M31 using the
next generation of wide field imaging telescopes with fields of view in the
square degree range. We consider proposals for such imagers both on the ground
and in space. For concreteness, we specialize to the SNAP proposal for a space
telescope and the LSST proposal for a ground based telescope. We find that a
modest space-based survey of 50 visits of one hour each is considerably better
than current ground based surveys covering 5 years. Crucially, systematic
effects can be considerably better controlled with a space telescope because of
both the infrared sensitivity and the angular resolution. To be competitive, 8
meter class wide-field ground based imagers must take exposures of several
hundred seconds with several day cadence.Comment: 10 pages, 4 figures, 2 table
Force reflecting hand controller
A universal input device for interfacing a human operator with a slave machine such as a robot or the like includes a plurality of serially connected mechanical links extending from a base. A handgrip is connected to the mechanical links distal from the base such that a human operator may grasp the handgrip and control the position thereof relative to the base through the mechanical links. A plurality of rotary joints is arranged to connect the mechanical links together to provide at least three translational degrees of freedom and at least three rotational degrees of freedom of motion of the handgrip relative to the base. A cable and pulley assembly for each joint is connected to a corresponding motor for transmitting forces from the slave machine to the handgrip to provide kinesthetic feedback to the operator and for producing control signals that may be transmitted from the handgrip to the slave machine. The device gives excellent kinesthetic feedback, high-fidelity force/torque feedback, a kinematically simple structure, mechanically decoupled motion in all six degrees of freedom, and zero backlash. The device also has a much larger work envelope, greater stiffness and responsiveness, smaller stowage volume, and better overlap of the human operator's range of motion than previous designs
Optimal Clustering under Uncertainty
Classical clustering algorithms typically either lack an underlying
probability framework to make them predictive or focus on parameter estimation
rather than defining and minimizing a notion of error. Recent work addresses
these issues by developing a probabilistic framework based on the theory of
random labeled point processes and characterizing a Bayes clusterer that
minimizes the number of misclustered points. The Bayes clusterer is analogous
to the Bayes classifier. Whereas determining a Bayes classifier requires full
knowledge of the feature-label distribution, deriving a Bayes clusterer
requires full knowledge of the point process. When uncertain of the point
process, one would like to find a robust clusterer that is optimal over the
uncertainty, just as one may find optimal robust classifiers with uncertain
feature-label distributions. Herein, we derive an optimal robust clusterer by
first finding an effective random point process that incorporates all
randomness within its own probabilistic structure and from which a Bayes
clusterer can be derived that provides an optimal robust clusterer relative to
the uncertainty. This is analogous to the use of effective class-conditional
distributions in robust classification. After evaluating the performance of
robust clusterers in synthetic mixtures of Gaussians models, we apply the
framework to granular imaging, where we make use of the asymptotic
granulometric moment theory for granular images to relate robust clustering
theory to the application.Comment: 19 pages, 5 eps figures, 1 tabl
Standing on the Shoulders of Giants: The Cleft Palate-Craniofacial Journal (1964-1989)Electronic Archive
Current research and clinical practice in cleft palate and craniofacial disorders âstands on the shoulders of giantsâ who came before us. To enable thirty years of seminal research articles to become digitally available to a worldwide community of students, scholars, and clinicians, a collaboration was forged in 2004 between University of Pittsburghâs Digital Research Library (DRL) and ACPA, (with the agreement of Allen Press), to create an electronic archive of the first thirty years of the Cleft Palate Craniofacial Journal . The work was performed pro bono, by all parties
The Pareto Argument for Inequality Revisited
One of the more obscure arguments for Rawlsâ difference principle dubbed âthe Pareto argument for inequalityâ has been criticised by G. A. Cohen (1995, 2008) as being inconsistent. In this paper, we examine and clarify the Pareto argument in detail and argue (1) that justification for the Pareto principles derives from rational selfinterest and thus the Pareto principles ought to be understood as conditions of individual rationality, (2) that the Pareto argument is not inconsistent, contra Cohen, and (3) that the kind of bargaining model required to arrive at the particular unequal distribution that the difference principle picks out is a model that is not based on bargaining according to oneâs threat advantage
Experimental testing of four correction algorithms for the forward scattering spectrometer probe
Three number density correction algorithms and one size distribution correction algorithm for the Forward Scattering Spectrometer Probe (FSSP) were compared with data taken by the Phase Doppler Particle Analyzer (PDPA) and an optical number density measuring instrument (NDMI). Of the three number density correction algorithms, the one that compared best to the PDPA and NDMI data was the algorithm developed by Baumgardner, Strapp, and Dye (1985). The algorithm that corrects sizing errors in the FSSP that was developed by Lock and Hovenac (1989) was shown to be within 25 percent of the Phase Doppler measurements at number densities as high as 3000/cc
Summer Ephemeroptera, Plecoptera, and Trichoptera (EPT) Species Richness and Community Structure in the Lower Illinois River Basin of Illinois
Ephemeroptera, Plecoptera, and Trichoptera (EPT) species richness is useful for monitoring stream health, but no published studies in Illinois quantitatively document EPT richness or assemblage structure. The objectives of this study were to characterize adult EPT richness and structure and relate these to relative water at eight stream sites (160-69,300 km3 area) in the lower Illinois River Adults were ultra-violet light trapped in June, July, and August 1997. Nutrient enrichment by nitrate and nitrite nitrogen was strongly evident, in smaller drainages, while critical loss of stable habitat was observed in water bodies. Seventy EPT species were identified from 17,889 specimens. Trichoptera were by far the most speciose (41 species), followed by Ephemeroptera (26), and Plecoptera (3). Caddisflies also dominated species richness across sites, contributing 18.0 of the average 28.9 total EPT species collected. Site EPT richness varied significantly (F =5.51, p 0.003, df 7), with smaller drainages supporting greater richness, generally. Differences were also evident for months (F = 21.7, p =0.0001, df =2), with June being lower (11.8 average) than either July (20.6) or August (18.1) values. Hilsenhoff biotic index (HBI) scores did not vary significantly across sites (F 0.7, p =0.7, df =7), but were different across months (F =5.4, p 0.02, df 2). June (4.23) and July (4.53) means were not different, but both were lower (of better quality) than August (5.33) scores. The relationship of EPT to HBI scores was not investigated statisti- cally due to problems of sample size and interdependance of monthly sam ples, but graphical analysis no consistent relationship. This sug- gested a decoupling of the the EPT and implied that the gain in taxonomic resolution achieved by adults outstripped the resolution of the HBI. Use of the HBI to characterize adult aquatic insect communities is discouraged. New state records and extensions for Ephemeroptera and Trichoptera are presented and loss of sensitive Plecoptera in the drainage is discussed
Synchronization in large directed networks of coupled phase oscillators
We extend recent theoretical approximations describing the transition to
synchronization in large undirected networks of coupled phase oscillators to
the case of directed networks. We also consider extensions to networks with
mixed positive/negative coupling strengths. We compare our theory with
numerical simulations and find good agreement
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