cssi/SciSciGPT-SciSciNet huggingface dataset:
Multidimensional poverty in Ethiopia : changes in overlapping deprivations

This paper presents trends in monetary and nonmonetary dimensions of wellbeing in Ethiopia using data from the Household Consumption and Expenditure and Welfare Monitoring surveys implemented in 2000, 2005, and 2011. The paper provides evidence on changes in overlapping deprivations using a non-index approach to multidimensional poverty. It assesses the performance of various dimensions in education, health, and living standards, taking one indicator at a time. It then examines the overlap between different dimensions of poverty and examines how this has changed over time in Ethiopia and across rural and urban areas. It highlights that although Ethiopia’s multidimensional poverty index is very high, there have been improvements in overlapping deprivations and, as a result, the number of individuals deprived in multiple dimensions has fallen.
EXOPLANET ALBEDO SPECTRA AND COLORS AS A FUNCTION OF PLANET PHASE, SEPARATION, AND METALLICITY

First generation space-based optical coronagraphic telescopes will obtain images of cool gas and ice giant exoplanets around nearby stars. The albedo spectra of exoplanets lying at planet-star separations larger than about 1 AU–where an exoplanet can be resolved from its parent star–are dominated by reflected light to beyond 1 µm and are punctuated by molecular absorption features. Here we consider how exoplanet albedo spectra and colors vary as a function of planet-star separation, metallicity, mass, and observed phase for Jupiter and Neptune analogs from 0.35 to 1 µm. We model Jupiter analogs with 1× and 3× the solar abundance of heavy elements, and Neptune analogs with 10× and 30× solar abundance of heavy elements. Our model planets orbit a solar analog parent star at separations of 0.8 AU, 2 AU, 5 AU, and 10 AU. We use a radiativeconvective model to compute temperature-pressure profiles. The giant exoplanets are found to be cloud-free at 0.8 AU, possess H2O clouds at 2 AU, and have both NH3 and H2O clouds at 5 AU and 10 AU. For each model planet we compute moderate resolution (R = λ/∆λ ∼ 800) albedo spectra as a function of phase. We also consider low-resolution spectra and colors that are more consistent with early direct imaging capabilities. As expected, the presence and vertical structure of clouds strongly influence the albedo spectra since cloud particles not only affect optical depth but also have highly directional scattering properties. Observations at different phases also probe different volumes of atmosphere as the source-observer geometry changes. Because the images of the planets themselves will be unresolved, their phase will not necessarily be immediately obvious, and multiple observations will be needed to discriminate between the effects of planet-star separation, metallicity, and phase on the observed albedo spectra. We consider the range of these combined effects on spectra and colors. For example, we find that the spectral influence of clouds depends more on planet-star separation and hence atmospheric temperature than metallicity, and it is easier to discriminate between cloudy 1× and 3× Jupiters than between 10× and 30× Neptunes. In addition to alkalis and methane, our Jupiter models show H2O absorption features near 0.94 µm. While solar system giant planets are well separated by their broad-band colors, we find that arbitrary giant exoplanets can have a large range of possible colors and that color alone cannot be relied upon to characterize planet types. We also predict that giant exoplanets receiving greater insolation than Jupiter will exhibit higher equator to pole temperature gradients than are found on Jupiter and thus may exhibit differing atmospheric dynamics. These results are useful for future interpretation of direct imaging exoplanet observations as well as for deriving requirements and designing filters for optical direct imaging instrumentation.
Copper(II)-catalyzed amidations of alkynyl bromides as a general synthesis of ynamides and Z-enamides. An intramolecular amidation for the synthesis of macrocyclic ynamides.

A general and efficient method for the coupling of a wide range of amides with alkynyl bromides is described here. This novel amidation reaction involves a catalytic protocol using copper(II) sulfate-pentahydrate and 1,10-phenanthroline to direct the sp-C−N bond formation, leading to a structurally diverse array of ynamides including macrocyclic ynamides via an intramolecular amidation. Given the surging interest in ynamide chemistry, this atom economical synthesis of ynamides should invoke further attention from the synthetic organic community.
Spatial localization of moment deficits in southern California

[1] The balance between interseismic elastic strain accumulation and coseismic release defines the extent to which a fault system exhibits a surplus or deficit of large earthquakes. We calculate the regional moment accumulation rate in southern California based on a fault slip rate catalog estimated from a block model of interseismic deformation constrained by GPS measurements. The scalar moment accumulation rate, 17.8 ± 1.1 × 1018 N m/yr, is approximately 50% larger than the average moment release rate over the last 200 years. Differences between the accumulated and released elastic displacement fields are consistent with moment deficits that are localized in three regions: the southern San Andreas and San Jacinto faults, offshore faults and the Los Angeles and Ventura basins, and the Eastern California Shear Zone. The moment budget could be balanced by coseismic events with a composite magnitude of Mw ≈ 8.
Solving single-digit sudoku subproblems

We show that single-digit "Nishio" subproblems in n×n Sudoku puzzles may be solved in time o(2n), faster than previous solutions such as the pattern overlay method. We also show that single-digit deduction in Sudoku is NP-hard.
Polarized neutron diffraction in high magnetic fields

Abstract The use of magnetic fields in the general area of neutron scattering is briefly surveyed, and some specific areas of research are identified which would benefit by the availability of higher fields. Since most of the past work combining neutron scattering and high magnetic fields has involved the polarized neutron technique, a description of this technique is presented along with a discussion of experimental errors produced by the magnetic field. The current status of polarized-beam research in four areas is reviewed: induced form factors in transition metals, mixed-valence systems, Kondo systems and complicated paramagnets.
Discussion of Some Myths/Features Associated With Gas Turbine Inlet Fogging and Wet Compression

Gas turbine inlet fogging and overspray (high-fogging) have been considered the most cost-effective means of boosting a gas turbine's total power output, especially under hot or dry weather conditions. The result of employing fogging or overspray is indisputably clear − total power output is increased; however, development of the theory and explanation of the phenomena associated with fogging and overspray are not always consistent and are sometimes misleading and incorrect. This paper focuses on reviewing several interesting features and commonly discussed topics, including (a) entropy production of water evaporation, (b) the effect of centrifugal force on water droplets, and (c) whether water droplets can survive the journey in the compressor and enter the combustor. Furthermore, three turbine myths: that fogging/overspray increases the air density in the compressor, reduces the compressor power consumption, and noticeably enhances the gas turbine efficiency, are examined and discussed. Some common mistakes in describing the compressor work are identified and corrected. A newly constructed multiphase T-S diagram is used to explain the physics of water droplet evaporation process and corresponding entropy production during wet compression. NOMENCLATURE
Lasers, extreme UV and soft X-ray

Three decades ago, large ICF lasers that occupied entire buildings were used as the energy sources to drive the first X-ray lasers. Today X-ray lasers are tabletop, spatially coherent, high-repetition rate lasers that enable many of the standard optical techniques such as interferometry to be extended to the soft X-ray regime between wavelengths of 10 and 50 nm. Over the last decade X-ray laser performance has been improved by the use of the grazing incidence geometry, diode-pumped solid-state lasers, and seeding techniques. The dominant X-ray laser schemes are the monopole collisional excitation lasers either driven by chirped pulse amplification (CPA) laser systems or capillary discharge. The CPA systems drive lasing in neon-like or nickel-like ions, typically in the 10 – 30 nm range, while the capillary system works best for neon-like argon at 46.9 nm. Most researchers use nickel-like ion lasers near 14 nm because they are well matched to the Mo:Si multilayer mirrors that have peak reflectivity near 13 nm and are used in many applications. As a result, the last decade has seen the birth of the X-ray free electron laser (XFEL) that can reach wavelengths down to 0.15 nm and the inner-shell Ne laser at 1.46 nm.
AN IMPLICIT CLIENTELE TEST OF THE RELATIONSHIP BETWEEN TAXATION AND CAPITAL STRUCTURE

This paper presents a test for the existence of high and low tax bracket debt clienteles. The test generates some evidence consistent with the implication of debt clientele theory that over time, firms' debt ratios should vary with the relative tax incentives for investors to hold debt. The results, however, do not support the existence of extreme financial leverage clienteles. Rather they are consistent with an incomplete equity market: low tax bracket investors hold the stock of highly levered firms and high tax bracket investors hold the stock of the low leverage firms.
Stereoselective Synthesis of Tetrahydrofurans via Formal [3+2]-Cycloaddition of Aldehydes and Allylsilanes. Formal Total Synthesis of the Muscarine Alkaloids (−)-Allomuscarine and (+)-Epimuscarine

The stereoselective synthesis of tetrahydrofurans was achieved by formal [3+2]-cycloaddition of allyl and crotylsilanes with α-triethylsilyloxy aldehydes. The scope of the reaction was examined by using different α-substituted aldehydes and different substituents on the silicon. Tamao oxidation of the products resulted in formation of diols that are easily functionalized allowing an entry to natural products synthesis. The formal total synthesis of the muscarine alkaloids (−)-allomuscarine and (+)-epimuscarine was achieved.
Laccase-generated quinones in naphthoquinone synthesis via Diels–Alder reaction

Abstract The tandem synthesis of naphthoquinones was conducted from the reaction of laccase-generated quinones and acyclic dienes via Diels–Alder reaction. This reaction was carried out under mild condition in aqueous medium and yielded naphthoquinones up to 80%. In addition, the effect of solvent was also investigated and water was shown to be optimal for this reaction.
Modulation of in vivo muscle power output during swimming in the African clawed frog (Xenopus laevis).

SUMMARY The goal of this study is to explore how swimming animals produce the wide range of performance that is seen across their natural behaviors. In vivo recordings of plantaris longus muscle length change were obtained by sonomicrometry. Simultaneous with muscle length data, force measurements were obtained using a novel tendon buckle force transducer placed on the Achilles tendon of Xenopus laevis frogs during brief accelerating bursts of swimming. In vivo work loops revealed that the plantaris generates a variable amount of positive muscle work over a range of swimming cycle durations (from 0.23 to 0.76 s), resulting in a large range of cycle power output (from 2.32 to 74.17 W kg –1 muscle). Cycle duration correlated negatively with cycle power, and cycle work correlated positively (varying as a function of peak cycle stress and, to a much lesser extent, fascicle strain amplitude). However, variation in cycle duration only contributed to 12% of variation in power, with cycle work accounting for the remaining 88%. Peak cycle stress and strain amplitude were also highly variable, yet peak stress was a much stronger predictor of cycle work than strain amplitude. Additionally, EMG intensity correlated positively with peak muscle stress ( r 2 =0.53). Although the timing of muscle recruitment (EMG phase and EMG duty cycle) varied considerably within and among frogs, neither parameter correlated strongly with cycle power, cycle work, peak cycle stress or strain amplitude. These results suggest that relatively few parameters (cycle duration, peak cycle stress and strain amplitude) vary to permit a wide range of muscle power output, which allows anurans to swim over a large range of velocities and accelerations.
Efficient Power Combining

The objective of this paper is to establish understanding of the single/multimode oscillator circuits used in combiners. A model is developed with emphasis on the selection and realization of the input/output coefficients, optimum stabilizing and output loads, equalizing network synthesis, and other cogent features. The application of this theory to the highly successful and efficient design of J-band pulsed oscillators will be discussed.
Plasmonic quantum cascade laser antenna

We demonstrate the plasmonic quantum cascade laser antenna, that can confine mid- infrared radiation beyond the diffraction limit, by integrating gold optical antennas on the laser facet.
Energy-Efficient Task Mapping for Data-Driven Sensor Network Macroprogramming

Data-driven macroprogramming of wireless sensor networks (WSNs) provides an easy to use high-level task graph representation to the application developer. However, determining an energy-efficient initial placement of these tasks onto the nodes of the target network poses a set of interesting problems. We present a framework to model this task-mapping problem arising in WSN macroprogramming. Our model can capture placement constraints in tasks, as well as multiple possible routes in the target network. Using our framework, we provide mathematical formulations for the task-mapping problem for two different metrics-energy balance and total energy spent. For both metrics, we address scenarios where (1) a single or (2) multiple paths are possible between nodes. Due to the complex nature of the problems, these formulations are not linear. We provide linearization heuristics for the same, resulting in mixed-integer programming (MIP) formulations. We also provide efficient heuristics for the above. Our experiments show that our heuristics give the same results as the MIP for real-world sensor network macroprograms, and show a speedup of up to several orders of magnitude. We also provide worst-case performance bounds of the heuristics.
Learning Prices for Repeated Auctions with Strategic Buyers

Inspired by real-time ad exchanges for online display advertising, we consider the problem of inferring a buyer's value distribution for a good when the buyer is repeatedly interacting with a seller through a posted-price mechanism. We model the buyer as a strategic agent, whose goal is to maximize her long-term surplus, and we are interested in mechanisms that maximize the seller's long-term revenue. We define the natural notion of strategic regret — the lost revenue as measured against a truthful (non-strategic) buyer. We present seller algorithms that are no-(strategic)-regret when the buyer discounts her future surplus — i.e. the buyer prefers showing advertisements to users sooner rather than later. We also give a lower bound on strategic regret that increases as the buyer's discounting weakens and shows, in particular, that any seller algorithm will suffer linear strategic regret if there is no discounting.
Sustainable cooperative robotic technologies for human and robotic outpost infrastructure construction and maintenance

Robotic Construction Crew (RCC) is a heterogeneous multi-robot system for autonomous acquisition, transport, and precision mating of components in construction tasks. RCC minimizes use of resources constrained by a space environment such as computation, power, communication, and sensing. A behavior-based architecture provides adaptability and robustness despite low computational requirements. RCC successfully performs several construction related tasks in an emulated outdoor environment despite high levels of uncertainty in motions and sensing. This paper provides quantitative results for formation keeping in component transport, precision instrument placement, and construction tasks.
Structure of Competitive Transit Networks

This paper describes the network shapes and operating characteristics that allow a transit system to deliver an accessibility level competitive with that of the automobile. To provide exhaustive results for service regions of different sizes and demographics, the paper idealizes these regions as squares with uniform demand, and their possible networks as a broad and realistic family that combines the grid and the hub-and-spoke concepts. The paper also shows how to use these results to generate master plans of transit systems for real cities. The analysis reveals which network structure and technology (Bus, Bus Rapid Transit, or Metro) delivers the desired performance with the least cost. It is found that the more expensive the system's infrastructure, the more it should tilt toward the hub-and-spoke concept. Bus Rapid Transit (BRT) competes effectively with the automobile unless a city is big and its demand low. This happens despite the uniform demand assumption, which penalizes collective transport. It is also found that if a city has enough suitable streets on which to run Bus and BRT systems, these outperform Metro even if the city is large and the demand high. Agency costs are always small compared with user costs; and both decline with the demand density. In all cases, increasing the spatial concentration of stops beyond a critical level increases both, the user and agency costs. Too much spatial coverage is counterproductive.
Bidding for Army Career Specialties: Improving the ROTC Branching Mechanism

Motivated by the low retention rates of US Military Academy and Reserve Officer Training Corps graduates, the Army recently introduced incentives programs in which cadets could bid 3 years of additional service obligation to obtain higher priority for their desired branches. The full potential of this incentives program is not utilized because of the ROTC’s deficient matching mechanism. I propose a design that eliminates these shortcomings and mitigates several policy problems the Army has identified. In contrast to the ROTC mechanism, my design utilizes market principles more extensively, and it is a hybrid between a market mechanism and a priority-based allocation mechanism.
Nafion-catalyzed preparation of benzhydryl ethers

Nafion-H is found to be an efficient and recyclable catalyst for the preparation of diphenylmethyl ethers of alcohols.
Homology cylinders: an enlargement of the mapping class group

We consider a homological enlargement of the mapping class group, dened by homology cylinders over a closed oriented surface (up to homology cobordism). These are important model objects in the recent Goussarov-Habiro theory of nite-type invariants of 3-manifolds. We study the structure of this group from several directions: the relative weight l- tration of Dennis Johnson, the nite-type ltration of Goussarov-Habiro, and the relation to string link concordance. We also consider a new Lagrangian ltration of both the mapping class group and the group of homology cylinders. AMS Classication 57N10; 57M25
Bottleneck links, variable demand, and the tragedy of the commons

We study the price of anarchy of selfish routing with variable traffic rates and when the path cost is a nonadditive function of the edge costs. Nonadditive path costs are important, for example, in networking applications, where a key performance metric is the achievable throughput along a path, which is controlled by its bottleneck (most congested) edge. We prove the following results. In multicommodity networks, the worst-case price of anarchy under the lp path cost with 1 < p ≤∞ can be dramatically larger than under the standard l1 path cost. In single-commodity networks, the worst-case price of anarchy under the lp path cost with 1 < p < ∞ is no more than with the standard l1 path norm. (A matching lower bound follows trivially from known results.) This upper bound also applies to the l∞ path cost if and only if attention is restricted to the natural subclass of equilibria generated by distributed shortest path routing protocols. For a natural cost-minimization objective function, the price of anarchy with endogenous traffic rates (and under any lp path cost) is no larger than that in fixed-demand networks. Intuitively, the worst-case inefficiency arising from the “tragedy of the commons” is no more severe than that from routing inefficiencies. © 2012 Wiley Periodicals, Inc. NETWORKS, 2012 (An extended abstract of this article appeared in the Proceedings of the 17th Annual ACM-SIAM Symposium on Discrete Algorithms, January 2006.)
An Adaptive Vision-Based Approach to Decentralized Formation Control

Presented at the AIAA Guidance, Navigation, and Control Conference and Exhibit 16 - 19 August 2004, Providence, Rhode Island.
Cramer-Rao bounds for parametric shape estimation in inverse problems

We address the problem of computing fundamental performance bounds for estimation of object boundaries from noisy measurements in inverse problems, when the boundaries are parameterized by a finite number of unknown variables. Our model applies to multiple unknown objects, each with its own unknown gray level, or color, and boundary parameterization, on an arbitrary known background. While such fundamental bounds on the performance of shape estimation algorithms can in principle be derived from the Cramer-Rao lower bounds, very few results have been reported due to the difficulty of computing the derivatives of a functional with respect to shape deformation. We provide a general formula for computing Cramer-Rao lower bounds in inverse problems where the observations are related to the object by a general linear transform, followed by a possibly nonlinear and noisy measurement system. As an illustration, we derive explicit formulas for computed tomography, Fourier imaging, and deconvolution problems. The bounds reveal that highly accurate parametric reconstructions are possible in these examples, using severely limited and noisy data.
Calculation of atomic number states: a Bethe ansatz approach

We analyse the conditions for producing atomic number states in a one-dimensional optical box using the Bethe ansatz method. This approach provides a general framework, enabling the study of number state production over a wide range of realistic experimental parameters.
Field experiments on the effects of reserve prices in auctions: more Magic on the Internet

I present experimental evidence on the effects of minimum bids in first-price, sealed-bid auctions. The auction experiments manipulated the minimum bids in a preexisting market on the Internet for collectible trading cards from the game Magic: the Gathering. I examine a number of outcomes, including the number of participating bidders, the probability of sale, the levels of individual bids, and the auctioneer’s revenues. The benchmark theoretical model is one with symmetric, risk-neutral bidders with independent private values. The results verify a number of the predictions concerning equilibrium bidding. Many bidders behave strategically, anticipating the effects of the reserve price on others’ bids.
Reduction mechanism of fluoroethylene carbonate for stable solid–electrolyte interphase film on silicon anode

Fluoroethylene carbonate (FEC) is an effective electrolyte additive that can significantly improve the cycling ability of silicon and other anode materials. However, the fundamental mechanism of this improvement is still not well understood. Based on the results obtained from (6)Li NMR and X-ray photoelectron spectroscopy studies, we propose a molecular-level mechanism for how FEC affects the formation of solid electrolyte interphase (SEI) film: 1) FEC is reduced through the opening of the five-membered ring leading to the formation of lithium poly(vinyl carbonate), LiF, and some dimers; 2) the FEC-derived lithium poly(vinyl carbonate) enhances the stability of the SEI film. The proposed reduction mechanism opens a new path to explore new electrolyte additives that can improve the cycling stability of silicon-based electrodes.
Breeding Incentive Programs and Demand for California Thoroughbred Racing: The Tradeoff Between Quantity and Quality

Both quantity of horses and quality stimulate demand for horse race gambling. This paper addresses the potential for a quantity/quality tradeoff due to breeding incentives for California thoroughbreds. Econometric analysis is used to assess the demand for quality and quantity of horses, and results suggest the likely net benefit of breeding incentives on the industry at large.
Scaling Laws for Ultra-Short Hydrostatic Gas Journal Bearings

The journal bearings of the MIT micro-devices are located at the outer periphery of the rotor and are designed to operate at rotational speeds of order two million rpm in order to enable high-power densities with turbomachinery tip speeds near 500 m/s. These journal bearings are very short compared to their relatively large bearing diameters such that the bearing L/D is typically less than 0.1, that is at least one order of magnitude smaller than in conventional gas bearings. Thus, the ultra-short micro gas journal bearings essentially act as short annular seals and operate at Reynolds numbers of order 300, two orders of magnitude lower than conventional annular seals. The concepts that hold for turbulent flow, large scale annular seals do not apply to micro bearings and the laminar flow regime sets new challenges in the design, implementation and operation of ultra-short, high-speed gas bearings. In order to reach the goal of operating the MIT micro devices at full design speed, the micro-bearing design must be improved and engineering solutions need to be found to overcome the challenges of high-speed bearing operation. This paper is the first to derive the scaling laws for the dynamics of ultra-short hydrostatic gas journal bearings. The theory is established from first principles and enables a physics based characterization of the dynamic behavior of ultra-short hydrostatic gas bearings. The derived scaling laws for natural frequency and damping ratio show good agreement with experimental data. A simple criterion for whirl instability is found that only depends on bearing geometry. The scaling laws together with this criterion are used to delineate engineering solutions critical for stable high-speed bearing operation. Design charts are developed which provide the link between fabrication tolerances, bearing performance, and the tolerable level of rotor unbalance for a minimum required whirl ratio.
Ruthenium-catalyzed C-C coupling of fluorinated alcohols with allenes: dehydrogenation at the energetic limit of β-hydride elimination.

Ruthenium(II) complexes catalyze the CC coupling of 1,1-disubstituted allenes and fluorinated alcohols to form homoallylic alcohols bearing all-carbon quaternary centers with good to complete levels of diastereoselectivity. Whereas fluorinated alcohols are relatively abundant and tractable, the corresponding aldehydes are often not commercially available because of their instability.
Channeling of responses elicited by hypothalamic stimulation

SCIENTIFIC discovery, like mining, often progresses on a discontinuous course. Progress in one direction continues until a point of diminishing returns is reached. A new strike may produce a scurry of activity in another direction. The development of different techniques may prompt the reopening of a closed shaft. Only after a period of such exploration may a more complete picture of the field emerge. The history of the hypothalamus seems to be following such a course. Prior to the turn of this century, little attention was given to the hypothalamus. The fact that the obesity observed as part of the Friihlich syndrome was attributed to pituitary difficulties and not related to hypothalamic involvement clearly reflected the prevailing scientific bias. ANDERSON’ traced the history of this period and quoted the following portion of Friihlich’s remarks in 1940 at a symposium on the hypothalamus : “The discussions that I have attended the past two days have established the fact that we were wrong in 1901, that it was not the pituitary body but the hypothalamus, but then I must remind you that all we knew at that time was that the hypothalamus was an anatomical region lying beneath the thalamus. That is all we knew.” Following the classic work by KARPLUS and KREIDL,~ RANSON~~~ and his colleagues, and HESS,~~~ the hypothalamus became increasingly stressed as a significant area for the expression of emotion and motivated behavior. The fact that electrical stimulation in this region elicited a number of autonomic responses constituted a major portion of the evidence. Earlier reports emphasized the elicitation of isolated responses such as pupillary dilation and constriction, but there was a gradual awareness that stimulation was capable of activating integrated bodily changes characteristic of such states as rage, temperature regulation, eating and somnolence. For a brief period it was claimed that stimulation activated only the motor aspects of these states and not the motivational or affective components;7 however, later work demonstrated that the behavior elicited by hypothalamic stimulation had many properties in common with behavior motivated by more
Synthesis and testing of novel phenyl substituted side-Chain analogues of classical cannabinoids

Abstract A series of novel phenyl substituted side-chain analogues of classical cannabinoids were synthesized and their CB1 and CB2 binding affinities were evaluated relative to Δ 8 -THC and compound 2 . CB1 and CB2 binding assays indicate that the dimethyl and ketone analogues ( 3 ) and ( 6 ) display selectivity for the CB2 receptor in comparison to Δ 8 -THC and compound 2 . This study provides newer insights into the geometrical and functional group requirements of the ligand binding pockets of the CB1 and the CB2 receptors.
The Ongoing Evolution of US Retail: A Format Tug-of-War

The past 15-20 years have seen substantial and visible changes in the way US retail business is conducted. Explanations about what is happening in the retail sector have been dominated by two powerful and not fully consistent narratives: a prediction that retail sales will migrate online and physical retail will be virtually extinguished, and a prediction that future shoppers will almost all be heading to giant physical stores like warehouse clubs and supercenters. Although online retail will surely continue to be a force shaping the sector going forward and may yet emerge as the dominant mode of commerce in the retail sector in the United States, its time for supremacy has not yet arrived. We discuss evidence indicating that the warehouse clubs/supercenter format has had a greater effect on the shape of retail over the past 15-20 years We begin with an overview of the retail sector as a whole, which over the long term has been shrinking as a share of total US economic activity and in terms of relative employment share. The retail sector has experienced stronger-than average productivity growth, but this has not been accompanied by commensurate wage growth. After discussing the important e-commerce and warehouse clubs/supercenters segments, we look more broadly at changes across the structure of the retail sector, including scale, concentration, dynamism, and degree of urbanization. Finally, we consider the likely future course of the retail sector.
Boron-Mediated Stereoselective Syntheses of γ,γ-Disubstituted Allenamides

Propargylic boranes generated by lithiation of optically active N-propargyloxazolidinones undergo reaction with a range of aldehydes to produce γ,γ-disubstituted allenamides with good diastereoselectivity.
A strategy-proof test of portfolio returns

Traditional methods for analyzing portfolio returns often rely on multifactor risk assessment, and tests of significance are typically based on variants of the t-test. This approach has serious limitations when analyzing the returns from dynamically traded portfolios that include derivative positions, because standard tests of significance can be 'gamed' using options trading strategies. To deal with this problem we propose a test that assumes nothing about the structure of returns except that they form a martingale difference. Although the test is conservative and corrects for unrealized tail risk, the loss in power is small at high levels of significance. (This abstract was borrowed from another version of this item.)
Reflectance standards at ultraviolet wavelengths

Polytetrafluoroethylene (PTFE) is widely used in remote sensing applications requiring a diffuse reflectance standard for detector calibration. The bi-directional and directional-hemispherical reflectance properties of both pressed and sintered PTFE were measured at ultraviolet wavelengths to provide information for their use as standards in this spectral range. The reflectance decreases with decreasing wavelength for both geometries, and the ratio between the reflectances for these geometries remains constant for wavelengths from 300 nm to 400 nm.
Identification of Endogenous Social Effects: The Reflection Problem

This paper examines the reflection problem that arises when a researcher observing the distribution of behaviour in a population tries to infer whether the average behaviour in some group influences the behaviour of the individuals that comprise the group. It is found that inference is not possible unless the researcher has prior information specifying the compisition of reference groups. If this information is available, the prospects for inference depend critically on the population relationship between the variables defining reference groups and those directly affecting outcomes. Inference is difficult to implossible if these variables are functionally dependent or are statistically independent. The prospects are better if the variables defining reference groups and those directly affecting outcomes are moderately related in the population.
Fear of fire sales and the credit freeze

Is there any need to “clean” up a banking system in the midst of a crisis, by closing or recapitalizing weak banks and taking bad assets off bank balance sheets, or can one wait till the crisis is over? We argue that an “overhang” of impaired banks that may be forced to sell assets soon can reduce the current price of illiquid assets sufficiently that weak banks have no interest in selling them. Anticipating a potential future fire sale, cash rich buyers have high expected returns to holding cash, which also reduces their incentive to lock up money in term loans. The potential for a worse fire sale than necessary, as well as the associated decline in credit origination, could make the crisis worse, which is one reason it may make sense to clean up the system even in the midst of the crisis. We discuss alternative ways of cleaning up the system, and the associated costs and benefits.
Model inadequacy and mistaken inferences of trait-dependent speciation

Species richness varies widely across the tree of life, and there is great interest in identifying ecological, geographic, and other factors that affect rates of species proliferation. Recent methods for explicitly modeling the relationships among character states, speciation rates, and extinction rates on phylogenetic trees— BiSSE, QuaSSE, GeoSSE, and related models— have been widely used to test hypotheses about character state-dependent diversification rates. Here, we document the disconcerting ease with which neutral traits are inferred to have statistically significant associations with speciation rate. We first demonstrate this unfortunate effect for a known model assumption violation: shifts in speciation rate associated with a character not included in the model. We further show that for many empirical phylogenies, characters simulated in the absence of state-dependent diversification exhibit an even higher Type I error rate, indicating that the method is susceptible to additional, unknown model inadequacies. For traits that evolve slowly, the root cause appears to be a statistical framework that does not require replicated shifts in character state and diversification. However, spurious associations between character state and speciation rate arise even for traits that lack phylogenetic signal, suggesting that phylogenetic pseudoreplication alone cannot fully explain the problem. The surprising severity of this phenomenon suggests that many trait-diversification relationships reported in the literature may not be real. More generally, we highlight the need for diagnosing and understanding the consequences of model inadequacy in phylogenetic comparative methods. (Character evolution; extinction; macroevolution; speciation; statistics.)
Analysis and performance characteristics of the Seagate advanced air bearing slider

The challenge of increasing disc drive capacity and performance while improving reliability requires a departure from typical straight rail air bearing sliders. This paper proposes a shaped air bearing that uses sub-ambient pressure. This design improves reliability by increasing air bearing stiffness, decreasing fly tolerances, increasing pitch angle, minimizing roll and improving take-off performance. The shaped rails and partially stepped edges control the fly height profile. This paper presents modeling of the slider's steady state and dynamic performance. Also presented are take-off velocity comparisons with catamaran, contact start/stop performance and the design's contamination sensitivity. >
Quanta without Quantization

The dimensional properties of fields in classical general relativity lead to a tangent tower structure which gives rise directly to quantum mechanical and quantum field theory structures without quantization. We derive all the fundamental elements of quantum mechanics from the tangent tower structure, including fundamental commutation relations, a Hilbert space of pure and mixed states, measurable expectation values, Schrodinger time evolution, "collapse" of a state and the probability interpretation. The most central elements of string theory also follow, including an operator valued mode expansion like that in string theory as well as the Virasoro algebra with central charges.
Conformations of Linear Chains. Systematics and Suggestions for Nomenclature

There are six categories of calculated favored dihedral angles in linear MnX2n+2 chains. The Prelog−Klyne nomenclature is not helpful for classifying them, and we propose the following labels and symbols: A, anti, reserved for torsional angles within a few degrees of 180°; T, transoid, ω ≃ 165°; D, deviant, ω ≃ 150°; O, ortho, ω ≃ 90°; G, gauche, ω ≃ 60°; C, cisoid, ω ≃ 40°. With the exception of C, all of these categories have been observed in alkanes, perfluoroalkanes, or oligosilanes.
Frequency and predictors of medically attended injuries in HIV-infected children.

The extent to which medically attended injuries complicate the clinical course of HIVinfected (HIV+) children is unknown. In a cohort of HIV+ children delivered from 1985 to 1990 and aged less than 60 months, we determined medically attended injuries per 100 child-years, Injury Severity Scores (ISS), and predictors of medically attended injuries by using New York State Medicaid claims from 1986 to 1992 linked to birth certificates. Injury rates and ISS were compared to those of a population of black, inner city children aged less than 60 months from emergency room records. HIV+ children had slightly more injuries (19.3 vs. 16.8/100 child-years) but similar ISS (2.4 vs. 2.3). Predictors of injuries in HIV+ children included younger maternal age (24/100 child-years, p=0.008) and delivery outside of New York City (29/100 child-years, p=0.02). Illicit drug use and alcohol use were associated with greater ISS while cocaine use was associated with a higher rate of possibly intentional injuries. Medically attend...
An accurate analytical delay model for BiCMOS driver circuits

An analytical delay model for BiCMOS driver circuits is presented. The model is based on physical device parameters and can be used to estimate both the pull-up and the pull-down times for a variety of circuit configurations. The intrinsic delay associated with the bipolar transistors is taken into consideration by using a charge control model that incorporates the high-injection effects upon the current gain and the base transport factor. Separate sets of delay equations are derived for the pull-up and pull-down transient responses to account for significant differences between the two cases. The comparison with SPICE circuit simulation results shows that the new model predicts the respective delay times with less than 10% error in most cases. The influence of device dimensions upon the driver delay time is also investigated. The model has been applied to find an optimal area allocation between the CMOS and bipolar parts of the driver circuit when the total available area is limited as in the standard cell configuration. >
Composition and Conductivity of Tin Oxide Films Prepared by Pyrohydrolytic Decomposition of Tin(IV) Compounds

The conductivity of thin poly crystalline Sn oxide films prepared by spraying solutions of Sn(IV) compounds onto glass or quartz substrates was studied. Conductivity was decreased by increasing the temperature or prolonging the time of heating after hydrolysis, by substituting SnBr4 for SnCl4, and by substituting O2 for N2 during spraying. These effects are explained in terms of nonstoichiometry of the sample and the presence of residual halogens in the crystal lattice as detected by ion-probe analysis.
Distributed synchronous clocking

It has historically been difficult to distribute a well-aligned hardware clock throughout the physical extent of a synchronous processor. Traditionally, this task has been accomplished by distributing the output of a central oscillator over a tree-like network, with repeaters at necessary intervals. While straightforward in concept, this method suffers from poor reliability, poor scalability and high skew. In this paper, we present an alternative approach-Distributed Synchronous Clocking-that maintains the simplicity of synchronous operation without suffering the drawbacks of centralized clocking. A network of independent oscillators takes the place of the centralized clock source, providing separate clock signals to the physically distant parts of a computing system. A distributed error correction algorithm effects global phase alignment by utilizing Local comparisons of neighboring oscillator phase. In contrast to centralized clock distribution, distributed clocking has the inherent potential for complete scalability and graceful degradation. However, because oscillator phase is a modular quantity, a naive implementation of distributed synchronous clocking can suffer from mode-lock-the trapping of local oscillator phase in undesirable stable equilibria where global phase is not aligned. We present a simple method for eliminating this problem in k-ary Cartesian meshes and give a proof of its correctness for two-dimensional networks. An electronic implementation is also presented and several engineering issues relating to error tolerance are discussed. >
Optimized Cell Programming for Flash Memories With Quantizers

Multilevel flash memory contains blocks of cells that represent data by the amount of charge stored in them. The cell writing - or programming - process applies specified voltages in a sequential manner, injecting charge to achieve a desired level. Reducing a cell level requires a costly block erasure, so programming only increases cell levels. Parallel programming, whereby a common voltage is applied to a group of cells to inject charge simultaneously, simplifies circuitry and increases programming speed. However, cell-to-cell variations and limited programming round can adversely affect its precision. In this paper, we consider algorithms for efficient cell programming. Since cell levels are quantized to a discrete set of values, our objective is to minimize the number of cells that are not quantized to their target levels. For a specified number of programming rounds, we derive an optimal parallel programming algorithm with complexity that is polynomial in the number of cells. We extend the algorithm to account for intercell interference, where the voltage applied to a cell can affect the level of adjacent cells. We then consider noisy programming of a single cell, with and without feedback about the cell level. In both scenarios, we present an algorithm that, for a given number of programming rounds, minimizes the probability of an incorrect cell level.
Extent of Excess Far-Infrared Emission around Luminosity Class III Stars

With the Infrared Space Observatory, we conducted 3 ) 3 pixel imaging photometry of 12 luminosity class III stars, which were previously presumed to have dust particles around them, at far-infrared wave- lengths (60 and 90 km). Eleven out of 12 targets show a peak of excess (above photosphere) far-infrared emission at the location of the star, implying that the dust particles are truly associated with stars. To estimate the size of the excess emission source, the —ux ratio of center to boundary pixels of the 3 ) 3 array was examined. The radius of the dust emission is found to be D3000 to D10,000 AU for a thin shell distribution and D5000 to D25,000 AU for a uniform distribution. We consider three models for the origin of the dust: disintegration of comets, sporadic dust ejection from the star, and emission from nearby interstellar cirrus. The data seem to rule out the —rst model (as far as the ii Kuiper beltlike ˇˇ particles are assumed to be large blackbody grains) but do not enable us to choose between the other two models. Subject headings: circumstellar matterinfrared: starsstars: late-type Zuckerman, Kim, & Liu (1995) correlated the Bright Star Catalogue (Hoffleit & Warren 1991) and the Michigan Spectral Catalogue (Houk, Cowley, & Smith-Moore 1975- 1988) with the IRAS catalogs to determine which, if any, luminosity class III giant stars (—rst-ascent red giants) have associated circumstellar dust particles that radiate at far- infrared (far-IR) wavelengths. Of more than 40,000 class III giant stars in the two catalogs, they found that perhaps 300 have associated dust. The presence of particulate material near premain- sequence, main-sequence, asymptotic giant branch, and supergiant stars may be accounted for in rather straight- forward ways (remnants from the star formation for the for- mer two and mass loss for the latter two). But, there is no obvious way to produce and retain large amounts of dust near —rst-ascent giant stars, which are thought to be too old to still possess much leftover material and insufficiently evolved to have lost a signi—cant amount of their mass. However, one may conjecture that the presence of dust around —rst-ascent giants may involve one or more of the following phenomena: mass loss, binarity, planetary sys- tems, and evaporation of Kuiper belt material. Recently, Jura (1999) has analyzed three models for the dust around eight —rst-ascent giant stars: orbiting dust resulting from the disintegration of comets located in extrasolar analogs of the Kuiper belt, dust sporadically ejected from the star, and emission from particles in the interstellar medium that are accidentally near the star, the ii cirrus hot spot.ˇˇ Among the Zuckerman et al. (1995) list of 100, we observed 12 —rst-ascent giant stars with the PHOT instru- ment of the Infrared Space Observatory (ISO)2 to determine if the excess far-IR emission is truly associated with the stars and to estimate the size of the region that produces the excess far-IR emission.