cssi/SciSciGPT-SciSciNet huggingface dataset:
Software correlators as testbeds for RFI algorithms

In‐correlator techniques offer the possibility of identif ying and/or excising radio frequency interference (RFI) from interferometric observations at much higher time and/or frequency resolution than is generally possible with the final visibility dataset . Due to the considerable computational requirements of the correlation procedure, cross‐correla tors have most commonly been implemented using high‐speed digital signal processing boards, which typically require long development times and are difficult to alter once complete. “Softwar e" correlators, on the other hand, make use of commodity server machines and a correlation algorithm coded in a high‐level language. They are inherently much more flexible and can be devel oped ‐ and modified ‐ much more rapidly than purpose‐built “hardware" correlators. Software correlators are thus a natural choice for testing new RFI detection and mitigation techniques for interferometers. The ease with which software correlators can be adapted to test RFI detection algorithms is demonstrated by the addition of kurtosis detection and plotting to the widel y used DiFX software correlator, which highlights previously unknown short‐duration RFI at the Hancock VLBA station.
When Should Providers of Recreational Land be Immune from Liability

This article examines statutes that limit the liability of landowners who open their property for recreational use. We ask whether landowner immunity promotes efficient provision by owners and efficient entry by recreational users. We examine these questions in several contexts, depending on whether the land is developed or undeveloped, privately or publicly owned, and whether or not the owner charges an entry fee. Our main finding is that, for both privately and publicly owned land, owner immunity is more efficient than owner liability when the land is undeveloped, but this is not true when the land is developed.
Bose-Einstein condensation of an atomic gas with attractive interactions

Summary form only given. Recently Bose-Einstein condensation (BEG) of ultracold atomic gases has been realized. In these experiments the gases are so dilute that only two-body interactions are relevant. The stability and character of the condensate for atoms with negative scattering length remains a new challenge for manybody theory. We are experimentally investigating these questions using a permanent magnet trap to confine /sup 7/Li. By evaporative cooling, phase-space densities that are more than 100 times greater than those required for quantum degeneracy can be created.
A scanning laser rangefinder for a robotic vehicle

A scanning Laser Rangefinder (LRF) which operates in conjunction with a minicomputer as part of a robotic vehicle is described. The description includes both hardware and software. Also included is a discussion of our functional requirements relative to the state-of-the-art; a detailing of the instrument and its performance; a summary of the robot system in which the LRF functions; the software organization, interfaces, and description; and some applications to which the LRF has been put.
Explaining Agricultural Expansion, Resource Booms and Growth in Latin America

The following paper examines the main factors determining long-run agricultural land expansion in Latin America compared to other tropical regions. Given the importance of natural resource-based sectors for most economies in Latin America, the impact of price-induced "resource booms" on economic growth in the region is explored. In addition, the paper examines whether there is an inherent "boom and bust" pattern of economic development associated with agricultural land expansion in Latin America, and the extent to which economic policies in the region exacerbate this problem. The paper concludes by examining the role of targeted policies in alleviating the structural obstacles to Latin American agricultural and economic development.
Price and the health plan choices of retirees.

Abstract This study analyzes health plan choices of retirees in an employer-sponsored health benefits program that resembles “premium support” models proposed for Medicare. In this program, out-of-pocket premiums depend on when an individual retired and his or her years of service as of that date. Since this price variation is exogenous to unobserved plan attributes and retiree characteristics, it is possible to obtain unbiased premium elasticity estimates. The results indicate a significantly negative effect of premiums. The implied elasticities are at the low end of the range found in previous studies on active employees.
AN ANALYSIS OF DOMESTIC AND EXPORT DEMAND FOR U.S. COTTON

Expansion of the cotton industry depends on economic growth. Models were specified to estimate U.S. domestic and export demand with and without structural change. The results indicate that domestic demand increases with per capita GDP and decreases with rising oil prices. U.S. export demand for cotton expands with lower beginning stocks in the rest of the world and rising per capita income.
Decentralized event-triggered consensus of Linear Multi-agent Systems under Directed Graphs

An event-triggered control technique for consensus of multi-agent systems with general linear dynamics is presented. This paper extends previous work to consider agents that are connected using directed graphs. Additionally, the approach shown here provides asymptotic consensus with guaranteed positive inter-event time intervals. This event-triggered control method is also used in the case where communication delays are present. For the communication delay case we also show that the agents achieve consensus asymptotically and that, for every agent, the time intervals between consecutive transmissions is lower-bounded by a positive constant.
Stress-Rupture Strength and Microstructural Stability of W-Hf-C Wire-Reinforced Superalloy Composites

W-Hf-C/superalloy composites were found to be potentially useful for turbine blade applications on the basis of stress-rupture strength. The 100- and 1000-h rupture strengths obtained for 70 volume percent fiber composites tested at 1090°C (2000°F) were 420 and 280 MN/m 2 (61 000 and 41 000 psi). The investigation indicated that with better quality fibers, composites having 100- and 1000-h rupture strengths of 570 and 370 MN/m 2 (82 000 and 54 000 psi) may be obtained. Metallographic studies indicated sufficient fiber-matrix compatibility for long-time applications at 1090°C (2000°F) for 1000 h or more.
HYDROLOGICAL CONNECTIVITY OF ABANDONED CHANNEL WATER BODIES ON A COASTAL PLAIN RIVER

Oxbow lakes, sloughs and other floodplain depressions associated with former channel positions are critical elements of floodplain hydrology, geomorphology and ecology. They comprise key elements of wetland and aquatic habitats and have important influence on the storage and routing of floodwaters. The hydrological connectivity between active river channels and floodplain depressions varies considerably in a qualitative sense, even within a single fluvial system. Several oxbows, sloughs and paleochannels were examined on the lower Sabine River, Texas/Louisiana, during a period of high but sub-bankfull flow as well as at lower flows. Six different types of surface water connectivity with the main, active channel were identified: (i) flow through—a portion of the river flow regularly passes through the feature and returns to the main channel; (ii) flood channel—there is no hydraulic connection at normal flows, but at high flows the channels convey discharge, at least part of which returns to the main channel; (iii) fill and spill—the features fill to a threshold level at high flows and then overflow (mainly via ephemeral channels) into flood basins; (iv) fill and drain—the features fill at high river discharges but do not (except in large floods) overflow because as river discharge declines, water drains back to the river; (v) tributary occupied—tributaries draining to the abandoned channel continue to occupy it, flowing through it to the active channel; and (vi) disconnected—no flow is exchanged except during large floods. The age or stage of infilling and the relative elevation of abandoned channels are important first-order controls of hydrological connectivity, but the lateral distance from the active channel is poorly related. Other critical controls are whether the cutoff section receives tributary input and whether a tie channel forms. The alluvial valley geomorphic context—specifically the presence of a meander belt ridge and flood basins—is also critical. Copyright © 2011 John Wiley & Sons, Ltd.
A New Inlining Algorithm for Mapping XML DTDs to Relational Schemas

XML is rapidly emerging on the World Wide Web as a standard for representing and exchanging data. It is critical to have efficient mechanisms to store and query XML documents to exploit the full power of this new technology. While one approach is to develop native XML repositories that support XML data models and query languages directly, the other approach is to take advantage of the mature technologies that are provided by current relational or object-relational DBMSs. There is active research along both approaches and it is still not clear which one is better than the other. We continue our effort on the second approach. In particular, we have developed an efficient algorithm which takes an XML DTD as input and produces a relational schema as output for storing and querying XML documents conforming to the input DTD. Our algorithm features several significant improvements over the shared-inlining algorithm including overcoming its incompleteness, eliminating redundancies caused by shared elements, performing optimizations and enhancing efficiency.
Specification diagnostics for duration models: A martingale approach

Abstract This paper develops specification diagnostics for discrete time duration models which are based on the martingale theory of stochastic processes. The methods can be applied to parametric grouped data duration models with time-varying covariates, right censoring, and which account for unobserved heterogeneity. A residual process is defined such that, under the correct model specification, the process is (approximately) a martingale difference sequence. Chi-square tests based on these residuals are derived. Results from Monte Carlo simulations are presented.
An adaptive policy for improved timeliness in secure database systems

Database systems for real-time applications must satisfy timing constraints associated with transactions, in addition to maintaining data consistency. In addition to real-time requirements, security is usually required in many applications. Multilevel security requirements introduce a new dimension to transaction processing in real-time database systems. In this paper, we argue that because of the complexities involved, tradeoffs need to be made between security and timeliness. We first describe a secure two-phase locking protocol. The protocol is then modified to support an adaptive method of trading off security for timeliness, depending on the current state of the system. The performance of the Adaptive 2PL protocol is evaluated for a spectrum of security-factor values ranging from fully secure (1.0) right upto fully real-time (0.0).
Genetics of Carney complex and related familial lentiginoses, and other multiple tumor syndromes.

Carney complex is a multiple endocrine neoplasia (MEN) syndrome that affects the adrenal cortex, the pituitary and thyroid glands, and the. gonads. The complex is also associated with skin and muco...
Compact encodings for all local path information in web taxonomies with application to wordnet

We consider the problem of finding a compact labelling for large, rooted web taxonomies that can be used to encode all local path information for each taxonomy element. This research is motivated by the problem of developing standards for taxonomic data, and addresses the data intensive problem of evaluating semantic similarities between taxonomic elements. Evaluating such similarities often requires the processing of large common ancestor sets between elements. We propose a new class of compact labelling schemes, designed for directed acyclic graphs, and tailored for applications to large web taxonomies. Our labelling schemes significantly reduce the complexity of evaluating similarities among taxonomy elements by enabling the gleaning of inferences from the labels alone, without searching the data structure. We provide an analysis of the label lengths for the proposed schemes based on structural properties of the taxonomy. Finally, we provide supporting empirical evidence for the quality of these schemes by evaluating the performance on the WordNet taxonomy.
Frazil Ice Formation: A Review

The problems associated with frazil ice formation are examined, the current state-of-the-art is reviewed, and recommendations for future research are made. No priorities are assigned to these recommendations. Future research should focus on obtaining heat transfer data, temperature measurements, flow measurements, physical measurements on frazil ice crystals (particularly frazil ice concentration), frazil ice nucleation processes, evolution of frazil ice crystals, anchor ice formation, forecasting the occurence of frazil ice, entrainment of frazil ice crystals in the flow and the resulting two-phase flow, adherence of frazil ice crystals to each other and to objects in the flow, granular growth in pans, floe producing mechanisms in rivers, and the initiation and development of river ice covers from frazil ice. The greatest need is for field measurements and field investigations of the preceding problems during periods of frazil ice formation in rivers.
Estimating Child Time Preferences: Aiding Rural Schools in Improving Human Capital Formation

We experimentally investigate the distribution of children's time preferences along gender and racial lines. Black boys have significantly larger discount rates than any other demographic group. Discount rates among Black girls are comparable to rates among White girls. Although White boys exhibit higher discount rates than girls, the difference is small and not statistically significant. These results are robust to alternative measures of patience and to regression analyses that control for socio-economic background and school performance. The measured differences in discount rates are large. All things equal, a Black boy requires expected returns to education 13-15% higher than Black girls to compensate for his larger discounting of future payoffs. Equally importantly, we show that impatience, as measured by discount rates, has a direct effect on behavior. An increase of one standard deviation in the discount rate increases by 5 percent the probability that a child incurs at least 3 school-related disciplinary actions. This result suggests that experiments capture new and relevant information on children. Overall, our results suggests that time preferences might play a large role in setting appropriate incentives for children. Understanding the factors behind these differences in preferences is an important area for future research.
La ciudad de la nueva economía.

Resumen es: En el proceso de cambio historico que vivimos, definido como "era de la informacion", el articulo situa la importancia de las ciudades, refiriendose a la...
An Assessment of A-C and D-C Potential Systems for Monitoring Fatigue Crack Growth

Electrical potential techniques for crack length measurements have been used for over 15 years to monitor subcritical crack growth. These techniques, based on the changes in electrical resistance of a specimen with crack extension, utilize either a d-c or, more recently, an a-c measurement system. The d-c and a-c systems are described, and the operating characteristics of two specific systems are discussed. A description of the empirical calibration of a specimen using these systems is included. Operating data are included for crack length measurements in a steel compact tension specimen. The d-c system, operated at a current of 10 A, had a crack length resolution of 0.013 mm. The a-c system, employing a lock-in amplifier as a tuned amplifier to provide noise rejection, can be operated at a much lower current of 0.75 A and provided a crack length resolution of 0.010 mm. By design, the a-c system would reject thermal (d-c) electromotive force introduced into the measurement circuit, whereas the d-c system had no such capability. Both systems, however, would be sensitive to changes in resistivity of the material with temperature. In materials of high magnetic permeability, alternating current is not uniformly distributed through the specimen thickness and tends to be concentrated near the specimen surface. The consequences of this "skin effect" in relation to crack length measurements are discussed. Operating procedures that assist in reducing noise and improving measurement sensitivity in both systems are described.
Cache oblivious algorithms

The cache oblivious model is a simple and elegant model to design algorithms that perform well in hierarchical memory models ubiquitous on current systems. This model was first formulated in [321] and has since been a topic of intense research. Analyzing and designing algorithms and data structures in this model involves not only an asymptotic analysis of the number of steps executed in terms of the input size, but also the movement of data optimally among the different levels of the memory hierarchy. This chapter is aimed as an introduction to the “ideal-cache” model of [321] and techniques used to design cache oblivious algorithms. The chapter also presents some experimental insights and results.
Chemical abundances in the damped Lyα systems

Reviewed in this paper are the recent and potential advances made with 10m-class telescopes on the chemical abundances of proto-galaxies in the early universe. In particular, we focus on measurements of the damped Ly(alpha) systems, layers of neutral hydrogen gas which dominate the HI content of the universe. Observed along the sightline to distant quasars, these systems are the progenitors of present-day galaxies. Therefore, analyses on the abundances of these systems provide direct insight into the chemical evolution of the universe at high redshift. The advent of 10m-class telescopes and efficient high resolution spectrographs have enables great progress on damped Ly(alpha) chemical abundances, particularly in two areas: (1) studies of the relative abundance patterns in the ISM of individual protogalaxies; and (2) metallicity measurements at z > 3. In this proceedings, we discuss these result and describe their impact on our understanding of chemical evolution in the early universe. Finally, we detail the areas of chemical abundance research that we believe should be the focus of future studies with current and new instruments on large telescopes.
The Anatomy of a Credit Crunch

What are the micro and macro implications of a credit crunch? We study this question in a model where heterogeneous entrepreneurs can finance their investment by borrowing subject to collateral constraints and/or by using internal funds. We discipline our theory by requiring that the size distribution and the dynamics of establishments in the model match those in the US data. We model a credit crunch in two complementary ways: (1) an unanticipated and temporary tightening of the collateral constraint; (2) an unanticipated and temporary increase in the wedge between deposit and lending rates. We show that a credit crunch has substantial impact on the size distribution and the dynamics of establishments, as well as on aggregate TFP, investment, and employment. In particular, the effects of a credit crunch differ significantly from those of exogenous TFP shocks. We compare our model predictions with the observed dynamics of establishments in the US during recessions to determine whether credit shocks are the main driving force behind aggregate fluctuations.
Promise Scholarship Programs as Place-Making Policy: Evidence from School Enrollment and Housing Prices ☆

Abstract Place-based “Promise” scholarship programs—which guarantee financial aid for qualifying graduates of a school district—have proliferated in recent years. Using data from multiple sites, we compare the evolution of school enrollment and residential real estate prices around program announcement dates within Promise-eligible and surrounding areas. While our estimates indicate that enrollment increased following Promise announcements, merit-based programs generated relative increases in white enrollment. Housing prices respond strongly in neighborhoods with better primary schools and in the upper half of the housing price distribution. We conclude that these programs have important and under-studied distributional considerations.
Interaction between radiation effects, gravity and other environmental factors in Tribolium confusum.

Multicellular organisms possess homeostatic control systems, which, in responding to changes of the external environment, modify the internal milieu of the organism accordingly, in order to make survival and normal physiological processes possible. This group has studied effects on physiological processes of single and combined environmental factors in the flour beetle, Tribolium confusum. Studies included low- and high-LET radiation, gravity compensation, near-weightlessness in space flight, ambient temperature, atmospheric composition, and magnetic field effects on the growth and development of Tribolium. For somatic effects, there appears to be a “normal physiological range” for each of these environmental variables; moreover, their effects seem independent of each other. When one of the listed environmental factors is near the limits of normal physiological tolerance, however, marked synergism has been observed between the effects of this factor and other environmental stresses. Fertilized Tribolium eggs showed a differential radiosensitivity to external irradiation, and a linear, dose-effect relationship was obtained, as accelerated heavy nitrogen and oxygen ions were used. Synergism was found when Tribolium were irradiated with ionizing radiation and subsequently exposed to temperature either below or above their normal physiological range. Gravity compensation or near-weightlessness in space flight have adverse effects on the development of Tribolium when an ambient temperature is near the higher or lower limit of tolerance. Similar results were observed when pupae were exposed to a combination of oxygen, temperature and magnetic field stresses.
MODULI STABILIZATION FROM FLUXES

Compactifications of IIB string theory with internal NS and RR three- form flux are computationally attractive since the lifting of moduli is via a perturbative and often explicitly calculable (super)potential. We focus on the T 6/Z 2 orientifold, and provide an illustative N = 2 example. For other choices of flux, the resulting equations of motion can be solved to yield N = 0,1,2 or 3 super- symmetry in four dimensions.
Competitiveness assessment of tourism in Sierra Leone : a cluster-based approach

Seven years out of brutal conflict, Sierra Leone is now a peaceful and stable country. Yet, its strides toward economic recovery and competitiveness have been modest even in sectors such as tourism, which used to be a major generator of foreign exchange revenues prior to the conflict. This paper presents a cluster-based analysis of the tourism sector in Sierra Leone. The analysis shows that tourism in Sierra Leone draws entirely on basic factor conditions such as natural endowments; high-end lodging, catering, and entertainment services are virtually nonexistent. The cluster mapping exercise reveals that several non-profit organizations are present and active within the Sierra Leone tourism cluster but that the role of commercial enterprises has been somewhat limited. A critical mass of basic service providers has emerged over time, but their functions are often hindered by the absence of a market-based incentive regime and weaknesses in backbone infrastructure services. There is a mismatch of effort by the public and private sectors. An important policy implication arising from the analysis is for Sierra Leone to initiate a joint action among tourism entrepreneurs and policymakers to develop a coherent business strategy toward overcoming the bottlenecks of skill deficiency, policy ineffectiveness, and lack of infrastructure and market access.
The Solar Neighbors in the Murky Depths of the Main Sequence

We discuss searches for brown dwarfs orbiting nearby stars and progress in defining the mass-luminosity relation for the lowest mass stars and brown dwarf candidates. We also outline how brown dwarfs fit into our current understanding of the nearest stars, and present the luminosity and mass functions for stars within 8 pc of the Sun.
Chandra Reveals the X-Ray Glint in the Cat's Eye

We have obtained Chandra ACIS-S observations of NGC 6543, the Cat's Eye Nebula. The X-ray emission from NGC 6543 is clearly resolved into a point source at the central star and diffuse emission confined within the central elliptical shell and two extensions along the major axis. Spectral analysis of the diffuse component shows that the abundances of the X-ray-emitting gas are similar to those of the fast (1750 km s-1) stellar wind but not those of the nebula. Furthermore, the temperature of this gas is ~1.7 × 106 K, which is 100 times lower than the expected postshock temperature of the fast stellar wind. The combination of low temperature and wind abundances is puzzling. The thermal pressure of this hot gas is about twice the pressure in the cool nebular shell; thus, the hot gas plays an essential role in the ongoing evolution of the nebula.
N-Body Integrators for Planets in Binary Star Systems

The discovery of planets orbiting in binary star systems represents an exciting new field of astrophysics. The stability of planetary orbits in binary systems can only be addressed analytically in special cases, so most researchers have studied stability using long-term N-body integrations of test particles, examining binary systems with a range of masses and orbits (e.g. Wiegert and Holman 1997; Haghighipour and Wiegert 1999; Haghighipour 2006). This has led to a good understanding of the likely regions of stability and instability in binary systems. Integrators can also been used to study the more complex problem of several finite-mass planets orbiting in a binary system, where interactions between the planets are significant. However, at the time of writing, this problem has been explored in less detail than the test-particle case, and we still lack a general theory for the stability of these systems.
Enzymes for Flavor Production

Introduction History Some Characteristic Features of Food Biotechnology Market Need Bioprocesses to Make Flavor and Aroma Chemicals Important Considerations in Developing a Successful Process Key Performance Parameters Technicocommercial Factors Protection of Technological Advantages Categorization of Bioflavor Processes Examples of Actual Bioflavor Processes The Application of Genetic Engineering Techniques to the Production of Bioflavors Downstream Processing Chromatography Cell Disruption Centrifugation Other Considerations Comparison of Different Processes Flavor Applications Constraints Product Approval and Registration Consumer Approval Future Opportunities Conclusions References Keywords: bioactive molecules; biocatalysis; downstream processing; fermentation; isolated enzymes; natural flavoring substances; nature-identical flavoring substances; receptor
Fischer-tropsch synthesis : Kinetics and effect of water for a Co/Al2O3 catalyst

The reason that cobalt catalysts display little activity for the water-gas-shift reaction, the amount of water present in the reactor during the Fischer-Tropsch (FT) synthesis reaction will be directly related to the CO conversion. It is therefore important to determine the impact of water partial pressure on the kinetics of the reaction, as well as the chemical and structural changes of the catalyst. This chapter reviews that the rate expression for FT synthesis has been obtained using a 25 wt.% Co/Al2O3 catalyst in a 1 liter continuously stirred tank reactor (CSTR) operated at 493K, 1.99 MPa (19.7 atm), H2/CO feed ratios of 1.0-2.4 with varying space velocities to produce 14-63% CO conversion. Adjusting the ratios of inert gas and added water permitted the impact of added water to be made at the same total flow rate and H2 and CO partial pressures. The addition of water at low levels during FT synthesis did not impact CO conversion but at higher levels it decreased CO conversion relative to the same conditions without water addition. The catalytic activity recovered after water addition was terminated. The temporary reversible decline in CO conversion when water was added may be due to the kinetic effect of water by inhibition of CO and/or H2 adsorption.
Verifying the Consistency of Remote Untrusted Services with Commutative Operations

A group of mutually trusting clients outsources a computation service to a remote server, which they do not fully trust and that may be subject to attacks. The clients do not communicate with each other and would like to verify the correctness of the remote computation and the consistency of the server’s responses. This paper first presents the Commutative-Operation verification Protocol (COP) that ensures linearizability when the server is correct and preserves fork-linearizability in any other case. All clients that observe each other’s operations are consistent, in the sense that their own operations and those operations of other clients that they see are linearizable. Second, this work extends COP through authenticated data structures to Authenticated COP , which allows consistency verification of outsourced services whose state is kept only remotely, by the server. This yields the first fork-linearizable consistency verification protocol for generic outsourced services that (1) relieves clients from storing the state, (2) supports wait-free client operations, and (3) handles sequences of arbitrary commutative operations.
The valuation of patents using third-party data: the Ocean Tomo 300 Patent Index

ABSTRACTThis study is the first investigation of the ability of the financial marketplace to value patent assets via exploiting the informational content of a widely quoted stock market patent index known as the Ocean Tomo 300 Patent Index (OT 300). The results suggest that the OT 300 ‘works,’ in the sense that the index generates buy-and-hold returns economically and statistically in excess of those of the market as a whole as well as a specially created 300-firm benchmark portfolio composed of other very liquid patent-holding firms.
Variational probabilistic inference and the QMR-DT network

We describe a variational approximation method for efficient inference in large-scale probabilistic models. Variational methods are deterministic procedures that provide approximations to marginal and conditional probabilities of interest. They provide alternatives to approximate inference methods based on stochastic sampling or search. We describe a variational approach to the problem of diagnostic inference in the "Quick Medical Reference" (QMR) network. The QMR network is a large-scale probabilistic graphical model built on statistical and expert knowledge. Exact probabilistic inference is infeasible in this model for all but a small set of cases. We evaluate our variational inference algorithm on a large set of diagnostic test cases, comparing the algorithm to a state-of-the-art stochastic sampling method.
X-ray absorption spectroscopy: diagnostic tool for probing material properties on dynamic experiments

In the most general sense we are proposing that X-ray absorption spectroscopy (XAS) be used to extract information from laser and pulsed power experiments. The technique will not be adaptable to all types of experiments but in its many forms may be useful for a large variety of cases. Here we describe a particular case in which a high Z (relative to the sample material) probe material is embedded in the sample and the time dependent absorption spectra of the probe is measured. The local temperature and pressure as well as other parameters affect the absorption spectrum of the probe and these parameters are then extracted from the XAS data.
Precision constrained simulation of the local Universe

We use the formalism of constrained Gaussian random fields to compute a precise large-scale simulation of the 60 h −1 Mpc volume of our local Universe. We derive the constraints from the reconstructed peculiar velocities of the 2MASS (Two Micron All-Sky Survey) Redshift Survey (2MRS). We obtain a correlation of 0.97 between the log density field of the dark matter distribution of the simulation and the log density of observed galaxies of the local Universe. We achieve a good comparison of the simulated velocity field to the observed velocity field obtained from the galaxy distances of the Nearby Galaxy Catalog 3000 km s −1 (NBG-3k, Tully et al.). At the end, we compare the two-point correlation function of both the 2MRS galaxies and the dark matter particles of the simulation. We conclude that this method is a very promising technique for exploring the dynamics and structure of the Universe in our neighbourhood.
Some solutions to the equity premium and volatility puzzles

In this paper, I adopt an economic equilibrium model utilizing the framework introduced by Mehra and Prescott (1985) when they presented the equity premium puzzle. This model, in the long run and with respect to stationary probabilities, produces results that match the sample values derived from the U.S. economy between 1889 and 1978 as illustrated by the studies performed by Grossman and Shiller (1981), which includes the expected average, standard deviation, and first-order serial correlation of the growth rate of per capita real consumption and the expected returns and standard deviation of equity, risk-free security, and risk premium for equity. Therefore, this model solves the equity premium and volatility puzzles. I also explore the reasons why the equity premium puzzle was caused.
Universal Behavior in Dirac Spectra

In these lectures we review recent results on universal fluctuations of QCD Dirac spectra and applications of Random Matrix Theory (RMT) to QCD. We review general properties of Dirac spectra and discuss the relation between chiral symmetry breaking and correlations of Dirac eigenvalues. In particular, we will focus on the microscopic spectral density density, i.e. the spectral density near zero virtuality on the scale of a typical level spacing. The relation with Leutwyler-Smilga sum-rules will be discussed. The success of applications of RMT to spectra of 'complex' systems leads us to the introduction of a chiral Random Matrix Theory (chRMT) with the global symmetries of the QCD partition function. Our central conjecture is that it decribes correlations of QCD Dirac spectra. We will review recent universality proofs supporting this conjecture. Lattice QCD results for the microscopic spectral density and for correlations in the bulk of the spectrum are shown to be in perfect agreement with chRMT. We close with a review of chRMT at nonzero chemical potential. Novel features of spectral universality in nonhermitean matrices will be discussed. As an illustration of mathematical methods used in RMT several important recent results will be derived in all details. We mention the derivation of the microscopic spectral density, the universality proof by Akemann, Damgaard, Magnea and Nishigaki, the spectral density of a chRMT at nonzero temperature and the Stephanov solution for chRMT at nonzero chemical potential.
Youth in Africa's Labor Market

Youth and Africa have received increased attention in recent policy discussions and World Bank work, as articulated in the Africa action plan and the World Development Report 2007: development and the next generation. The Africa action plan offers a framework to support critical policy and public action led by African countries to achieve well-defined goals, such as the Millennium Development Goals (MDGs). The World Development report's main message is that the time has never been better to invest in young people living in developing countries. It offers a three pillar policy framework for investing in and preserving the human capital of the next generation. Both frameworks respond to the desire to find solutions to Africa's development challenges and to prepare for and benefit from the next generation of workers, parents, and leaders. This report examines the challenges Africa's youth face in their transition to working life and proposes policies for meeting these challenges. It presents evidence from case studies of 4 countries - Burkina Faso, Ethiopia, Tanzania, and Uganda and from household data on 13 countries. The four case studies include a stocktaking of existing policies and programs to address youth employment and labor markets. The overarching message of the report is the call to further invest in the human capital of youth in Sub-Saharan Africa to take advantage of the large youth cohorts there. Youth in Africa leave school too early and enter the labor market unprepared, limiting their contribution to economic growth and increasing their vulnerability to poverty and economic hardship.
The species of Phora (Diptera: Phoridae) of Costa Rica

The Phora of Costa Rica were reviewed and three species, all belonging to Schmitz’s Group III, were recognized: P. americana Schmitz and Wirth, P. truncata new species and P. paramericana new species. Of the three species, P. americana is by far the most abundant, with the other two species being rarely collected. All specimens were collected in the central highlands of the country. The previous record of the Holarctic Region species P. stictica Meigen from Costa Rica was found to be based on a misidentification of P. truncata.
Preschool vision screening: Summary of a task force report

Vision screening to detect eye problems in school-aged children dates back at least a century.1 Calls to screen specifically for amblyopia, generally defined as monocular decreased acuity, began appearing by the 1950s.2 However, it was not until the 1960s, when animal research indicated that cortical plasticity was limited to a period early in life, that emphasis was placed on vision screening in the preschool years. Since that time, a variety of preschool screening programs have been adopted in various countries,3 ranging from the systematic and thorough efforts of Scandinavian countries that evaluate screening methods and outcome from infancy through preschool ages,3,4 to the diversity of screening standards (Table 1) and screening programs found in different jurisdictions across the United States.5,6 View this table: Table 1. Current Recommendations for Preschool Vision Screening Programs Recommendations for health-related screening programs, developed by the World Health Organization,7 require that a disorder suitable for mass screening should have a high prevalence in the population, should result in significant impairment to the individual, and should be treatable at the time of its detection. Although the Scandinavian experience and other data make clear the effectiveness of preschool screening in reducing visual morbidity from amblyopia,8–10 fundamental questions remain about specific issues, ranging from screening methodology to quantitative measures of both efficacy and cost-effectiveness of such screening. These questions were recently brought to focus by a report from the United Kingdom questioning the utility of preschool vision screening.11–13 Although both the data interpretation and conclusions of this report have been questioned,14–23 it has given impetus to a reexamination of the why and how of preschool vision screening. Recognizing the growing list of questions about preschool vision screening and the lack of consistency in preschool vision screening recommendations and programs in the United States, Congress urged …
Effective Approaches to Attention-based Neural Machine Translation

An attentional mechanism has lately been used to improve neural machine translation (NMT) by selectively focusing on parts of the source sentence during translation. However, there has been little work exploring useful architectures for attention-based NMT. This paper examines two simple and effective classes of attentional mechanism: a global approach which always attends to all source words and a local one that only looks at a subset of source words at a time. We demonstrate the effectiveness of both approaches on the WMT translation tasks between English and German in both directions. With local attention, we achieve a significant gain of 5.0 BLEU points over non-attentional systems that already incorporate known techniques such as dropout. Our ensemble model using different attention architectures yields a new state-of-the-art result in the WMT’15 English to German translation task with 25.9 BLEU points, an improvement of 1.0 BLEU points over the existing best system backed by NMT and an n-gram reranker. 1
The stock of money and why you should care

In this chapter, I will examine the problems created by incorrectly using a simple sum monetary aggregate (SSUM) to measure the monetary stock. Specifically, I will show that SSUM confounds the current stock of money (CSM) with the investment stock of money (ISM) and that this confounding leads the SSUM to report an artificially smooth monetary stock. This smoothing causes important information about the dynamic movements of the monetary stock to be lost. This may offer at least a partial explanation of why so many studies find that money has little economic relevance. To that end, we will conclude the chapter by examining a reduced form backward looking IS equation to determine whether monetary aggregates contain information about real GDP gap. This chapter differs from previous work in monetary aggregation in that it focuses on smoothing of the monetary stock data caused by the use of simple sum methodology, where the previous work focuses on the bias exhibited by SSUMs.
The units of a ring spectrum and a logarithmic cohomology operation

Recall that if R is a commutative ring, then the set R× ⊂ R of invertible elements of R is naturally an abelian group under multiplication. This construction is a functor from commutative rings to abelian groups. In general, there is no obvious relation between the additive group of a ring R and the multiplicative group of units R×. However, under certain circumstances one can define a homomorphism from a subgroup of R× to a suitable completion of R, e.g., the natural logarithm Q>0 → R, or the p-adic logarithm (1 + pZp) → Zp. The “logarithmic cohomology operation” is a homotopy-theoretic analogue of the above, where R is a commutative S-algebra and “completion” is Bousfield localization with respect to a Morava K-theory. The purpose of this paper is to give a formula for the logarithmic operation (in certain contexts) in terms of power operations. Before giving our results we briefly explain some of the concepts involved.
Monetary Policy Under Commodity Price Fluctuations

This paper discusses monetary policy in a New Keynesian open economy subject to commodity price fluctuations. We review theoretical results that imply that stabilizing the producer price index (PPI) is optimal only under special circumstances. In a calibrated version of the model, PPI targeting is compared against a policy that stabilizes a forecast of the consumer price index. The results depend on model specifics, especially elasticities of substitution and the structure of international asset markets.
Africa's macroeconomic story

Much of Sub-Saharan Africa's post-independence macroeconomic history has been characterized by boom-bust cycles. Growth accelerations have been common, but short lived. Weak policy formulation and implementation led to large external and fiscal imbalances, excessive debt accumulation, volatile inflation, and sharp exchange rate fluctuations. This characterization changed, however, in the mid-1990s, when debt relief and better macroeconomic policy began to provide a source of stability that has helped sustain robust growth throughout much of the region. In resource rich countries, the process was supported over the past few years by a dramatic increase in commodity prices. But resources are only one part of the story. Growth has exhibited impressive resilience even in the face of negative external shocks, as in 2008-2009. While the short-term outlook remains positive, over the medium term policy makers face new challenges. Several countries have the potential to greatly expand natural resource production and become major commodity exporters; volatile resource revenue will complicate their fiscal and monetary planning. Rising investor appetite for financial assets of frontier markets and the development of domestic debt markets will continue to broaden the menu of and trade-offs among financing options at a time when global interest rates may start sloping upward. Complex financing arrangements -- notably for private-public or public-public partnerships in infrastructure -- will become more common and will generate new types of fiscal commitments and contingencies.
Equilibria and Pareto optima of markets with adverse selection

This paper examines the efficiency properties of competitive equilibrium in an economy with adverse selection. The agents (firms and households) in this economy exchange contracts, which specify all the relevant aspects of their interaction. Markets are assumed to be complete, in the sense that all possible contracts can, in principle, be traded. Since prices are specified as part of the contract, they cannot be used as free parameters to equate supply and demand in the market for the contract. Instead, equilibrium is achieved by adjusting the probability of trade. If the contract space is sufficiently rich, it can be shown that rationing will not be observed in equilibrium. A further refinement of equilibrium is proposed, restricting agents' beliefs about contracts that are not traded in equilibrium. Incentive-efficient and constrained incentive-efficient allocations are defined to be solutions to appropriately specified mechanism design problems. Constrained incentive efficiency is an artificial construction, obtained by adding the constraint that all contracts yield the same rate of return to firms. Using this notion, analogues of the fundamental theorems of welfare economics can be proved: all refined equilibria are constrained incentive-efficient and all constrained incentive-efficient allocations satisfying some additional conditions can be decentralized as refined equilibria. A constrained incentive-efficient equilibrium is typically not incentive-efficient, however. The source of the inefficiency is the equilibrium condition that forces all firms to earn the same rate of return on each contract.
Catalytic palladium-mediated tetraene carbocyclizations: The efficient stereochemical control of newly formed methyl-bearing stereocenters

Abstract Certain tetraene substrates bearing a trisubstituted double bond as part of one of the diene subunits undergo palladium-catalyzed cascade cyclization to afford cyclized products in which a new methyl-bearing stereocenter is generated in a stereoselective fashion.
[M4(Se2)2(PSe4) 4]8-: A novel, tetranuclear, cluster anion with a stellane-like core

The molecular cluster compounds [M 4 (Se 2 ) 2 (PSe 4 ) 4 ] 8- (M=Cd, Hg) form by the reaction of Cd and Hg with basic polychalcophosphate fluxes.
A Compact Falling Film Absorber

The paper presents a new design of a falling film absorber that could considerably reduce the absorber size without penalizing the vapor and coolant side pressure drops. The proposed design is based on the fundamental characteristics of an efficient absorber design: large liquid-vapor interfacial area and good wetting characteristics. A finite difference scheme is developed to numerically investigate the performance of the design. The results indicate that the proposed design is more compact and efficient than the horizontal tube-type falling film absorber.