cssi/SciSciGPT-SciSciNet huggingface dataset:
Polynomial Sequences of Binomial-Type Arising in Graph Theory

In this paper, we show that the solution to a large class of "tiling'' problems is given by a polynomial sequence of binomial type. More specifically, we show that the number of ways to place a fixed set of polyominos on an $n\times n$ toroidal chessboard such that no two polyominos overlap is eventually a polynomial in $n$ , and that certain sets of these polynomials satisfy binomial-type recurrences. We exhibit generalizations of this theorem to higher dimensions and other lattices. Finally, we apply the techniques developed in this paper to resolve an open question about the structure of coefficients of chromatic polynomials of certain grid graphs (namely that they also satisfy a binomial-type recurrence).
Macroeconomic uncertainty and private investment in developing countries - an empirical investigation

The impact of uncertainty on investment has attracted considerable attention in the analytical and empirical macroeconomic literature. In theory, however, uncertainty can affect investment through different channels, some of which operate in mutually opposing direction. So, the sigh of its overall effect is ambiguous and can be assessed only empirically. To thoroughly assess the impact of macroeconomic uncertainty on private investment, the author uses a large panel data set on developing countries. He draws a distinction between sample variability and uncertainty, constructs alternative measure of the volatility of innovations to five key macroeconomic variables (inflation, growth, the terms of trade, the real exchange rate, and the price of capital goods), and examines their association with aggregate private investment. He then adds these constructed measures to an empirical investment equation that is estimated using alternative panel data econometric methods, allowing for simultaneity, country-specific effects, and parameter heterogeneity across countries. The results underscore the robustness of the link between investment and uncertainty. Virtually all of the volatility measures in the paper show a strong negative association with investment ratios. In addition, the regression estimates indicate that uncertainty has an adverse direct impact on investment, over and above any indirect effect that might also be at work. This finding is particularly robust in the case of real exchange rate volatility, which invariably has a robust negative effect on investment, regardless of econometric specification.
Multispectral and stereo imaging on Mars.

Relevant aspects of the design and function of the two-window Viking Landing Camera system are described, with particular reference to some results of its operation on Mars during the Viking mission. A major feature of the system is that the optical tunnel between the lens and the photosensor array contains a multiaperture baffle designed to reduce veiling glare and to attenuate radio frequency interference from the lander antennas. The principle of operation of the contour mode is described. The accuracy is limited by the stereo base, resolution of camera picture elements, and geometric calibration. To help determine the desirability as well as the safety of possible sample sites, use is made of both radiometric and photogrammetric information for each picture element to combine high-resolution pictures with low-resolution color pictures of the same area. Explanatory photographs supplement the text.
Does improved sanitation reduce diarrhea in children in rural India

Nearly nine million children under five years of age die annually. Diarrhea is considered to be the second leading cause of Under-5 mortality in developing countries. About one out of five deaths are caused by diarrhea. In this paper, we use the newly available data set DLHS-3 to quantify the impact of access to improved sanitation on diarrheal morbidity for children under five years of age in India. Using Propensity Score Matching (PSM) and propensity-based weighted regression, we find that access to improved sanitation reduces the risk of contracting diarrhea. Access to improved sanitation decreases child diarrhea incidence by 2.2 percentage points. There is considerable heterogeneity in the impacts of improved sanitation. We neither find statistically significant treatment eects for children in poor household nor for girls, however, boys and high socioeconomic status (SES) children experienced larger treatment effects. The results show that it is important to complement public policies on sanitation with policies that alleviate poverty, improve parent's education and promote gender equity.
Measurement and computation of the higher order modes of the ALS 500 MHz accelerating cavities

Higher order modes in the accelerating cavities are expected to drive coupled bunch instabilities in the ALS, which will be overcome by a bunch-by-bunch feedback system. Computations of the cavity higher order modes using the URMEL-T and MAFIA codes are presented. Damping of the higher order modes is achieved by filters in the high power feeder waveguide which is aperture coupled to the cavity. Measurements of the modes in an ALS 500 MHz cavity are presented and compared with the computed values for an isolated, un-damped cavity. The resources of the Lambertson Beam Electrodynamics Laboratory of the Center for Beam Physics at LBL were used to perform these studies. >
A structural approach to relaxation in glassy liquids

The relation between structure and dynamics in glasses is not fully understood. A new approach based on machine learning now reveals a correlation between softness—a structural property—and glassy dynamics. In contrast with crystallization, there is no noticeable structural change at the glass transition. Characteristic features of glassy dynamics that appear below an onset temperature, T0 (refs 1,2,3), are qualitatively captured by mean field theory4,5,6, which assumes uniform local structure. Studies of more realistic systems have found only weak correlations between structure and dynamics7,8,9,10,11. This raises the question: is structure important to glassy dynamics in three dimensions? We answer this question affirmatively, using machine learning to identify a new field, ‘softness’ which characterizes local structure and is strongly correlated with dynamics. We find that the onset of glassy dynamics at T0 corresponds to the onset of correlations between softness (that is, structure) and dynamics. Moreover, we construct a simple model of relaxation that agrees well with our simulation results, showing that a theory of the evolution of softness in time would constitute a theory of glassy dynamics.
Discrete Korn's inequality for shells

We prove discrete Korn's inequalities for Naghdi and Koiter shell models, which are applicable to discontinuous piecewise functions. They are useful in study of discontinuous finite element methods for shells.
On the interaction of radio waves with meteoric plasma

In this paper, a meteoric plasma is analyzed from a physical viewpoint, with particular emphasis on its interaction with radio waves. The attention is drawn to some macroscopic characteristics of a meteoric plasma and it is shown that the electron-ion collision frequency is not negligible, as commonly thought. Concerning the difference between back-scattering and forward-scattering, it is worth noting that the two systems use different types of radio waves. A forward-scattering radar uses a continuous sine wave, while a back-scattering one uses a pulsed wave. This influences the mathematical approach to the prob- lem, but also physical theories. The pulse shape of the back- scattering radar can be represented by a sum of several com- ponents with different frequencies. It follows that, during the propagation, the various components tend to change phase with respect to one another, which leads to a change in shape of the pulse. The dispersion relation thus depends on the frequency and can be expressed in a Taylor series. A detailed treatment of the pulse propagation in dielectrics is not the subject of this pa- per: the interested reader can find useful mathematical tools in, for example, Oughstun & Sherman (1997). Here we want only to underline that we cannot simply consider the signal emit- ted by a back-scattering radar as sinusoidal: thus, the extension of the back-scattering echo theory to forward-scattering is not correct. The purpose of this paper is to settle some basic concepts in meteor physics and we leave a "cook-book" approach to other articles. The interaction of sine waves (for the sake of simplicity) in the radio frequency range with meteoric plasma is investigated. We will see that the common assumption about meteors as a collisionless ionized gas does not have any physical ground.
On the growth of solutions to the minimal surface equation over domains containing a halfplane

We consider minimal graphs $$u = u(x,y) > 0$$ over unbounded domains D with $$u = 0$$ on $$\partial D$$ . Assuming D contains a sector properly containing a halfplane, we show that u grows at most linearly. We also provide examples illustrating a range of growth.
Fully automated obstacle-crossing gaits for walking machines

The authors present a study on fully automated gaits which can be used to cross over four standard types of obstacles: grade, ditch, step, and isolated-wall. These gaits are simulated using computer graphics. The designer can arbitrarily select the dimensions of one obstacle, the computer program then generates a series of preprogrammed movements which enables a hexapod to cross over the obstacle in a fully automated mode. This study demonstrates the feasibility of fully automated obstacle-crossing gaits for the use of an all-terrain walking machine. >
Use of the A. Victoria Green Fluorescent Protein to Study Protein Dynamics In Vivo

Fluorescent molecules serve as valuable tools for the detection of numerous biochemical phenomena and have been employed for protein localization, quantitation of gene expression, detection of nucleic acids, cell sorting and determination of chemical concentrations. However, the use of such techniques generally requires significant nonphysiological perturbations to the biological system being studied; therefore, they are not always appropriate for the observation of dynamic phenomena. Green fluorescent protein (GFP), cloned from jellyfish, has been used to overcome many of these problems. It is a small, extremely stable fluorescent protein that has been successfully expressed and detected in a wide variety of organisms, both in intact form and fused to other proteins. This overview unit describes the use of this proteinaceous fluorophore for in vivo observation of cellular phenomena.
A re-evaluation of empirical tests of the Fisher hypothesis

This paper shows that the recent literature that tests for a long-run Fisher relationship using cointegration analysis is seriously flawed. Cointegration analysis assumes that the variables in question are I(1) or I(d) with the same d. Using monthly post-war U.S. data from 1959-1997, we show that this is not the case for nominal interest rates and inflation. While we cannot reject the hypothesis that nominal interest rates have a unit root, we find that inflation is a long-memory process. A direct test for the equality of the fractional differencing parameter for both series decisively rejects the hypothesis that the series share the same order of integration.
Iterative Byzantine Vector Consensus in Incomplete Graphs

This work addresses Byzantine vector consensus, wherein the input at each process is a d-dimensional vector of reals, and each process is required to decide on a decision vector that is in the convex hull of the input vectors at the fault-free processes [9,12]. The input vector at each process may also be viewed as a point in the d-dimensional Euclidean space R d , where di¾?>i¾?0 is a finite integer. Recent work [9,12] has addressed Byzantine vector consensus, and presented algorithms with optimal fault tolerance in complete graphs. This paper considers Byzantine vector consensus in incomplete graphs using a restricted class of iterative algorithms that maintain only a small amount of memory across iterations. For such algorithms, we prove a necessary condition, and a sufficient condition, for the graphs to be able to solve the vector consensus problem iteratively. We present an iterative Byzantine vector consensus algorithm, and prove it correct under the sufficient condition. The necessary condition presented in this paper for vector consensus does not match with the sufficient condition for di¾?>i¾?1; thus, a weaker condition may potentially suffice for Byzantine vector consensus.
Quantifying mountain block recharge by means of catchment-scale storage-discharge relationships

[1] Despite the importance of mountainous catchments for providing freshwater resources, especially in semi-arid regions, little is known about key hydrological processes such as mountain block recharge (MBR). Here we implement a data-based method informed by isotopic data to quantify MBR rates using recession flow analysis. We applied our hybrid method in a semi-arid sky island catchment in southern Arizona, United States. Sabino Creek is a 91 km2 catchment with its sources near the summit of the Santa Catalina Mountains northeast of Tucson. Southern Arizona's climate has two distinct wet seasons separated by prolonged dry periods. Winter frontal storms (November–March) provide about 50% of annual precipitation, and summers are dominated by monsoon convective storms from July to September. Isotope analyses of springs and surface water in the Sabino Creek catchment indicate that streamflow during dry periods is derived from groundwater storage in fractured bedrock. Storage-discharge relationships are derived from recession flow analysis to estimate changes in storage during wet periods. To provide reliable estimates, several corrections and improvements to classic base flow recession analysis are considered. These corrections and improvements include adaptive time stepping, data binning, and the choice of storage-discharge functions. Our analysis shows that (1) incorporating adaptive time steps to correct for streamflow measurement errors improves the coefficient of determination, (2) the quantile method is best for streamflow data binning, (3) the choice of the regression model is critical when the stage-discharge function is used to predict changes in bedrock storage beyond the maximum observed flow in the catchment, and (4) the use of daily or night-time hourly streamflow does not affect the form of the storage-discharge relationship but will impact MBR estimates because of differences in the observed range of streamflow in each series.
Standardized Regression Coefficients

Standardized regression coefficients reflect the standard deviation change in a criterion variable associated with a standard deviation change in a predictor variable. Standardized regression coefficients permit comparisons of predictor–criterion relationships across studies in which the variables have been measured using different units of measure. Keywords: beta weight
Higher spin Fronsdal equations from the exact renormalization group

We show that truncating the exact renormalization group equations of free U(N) vector models in the single-trace sector to the linearized level reproduces the Fronsdal equations on AdS d+1 for all higher spin fields, with the correct boundary conditions. More precisely, we establish canonical equivalence between the linearized RG equations and the familiar local, second order differential equations on AdS d+1, namely the higher spin Fronsdal equations. This result is natural because the second-order bulk equations of motion on AdS simply report the value of the quadratic Casimir of the corresponding conformal modules in the CFT. We thus see that the bulk Hamiltonian dynamics given by the boundary exact RG is in a different but equivalent canonical frame than that which is most natural from the bulk point of view.
Critical Points in Two-Dimensional Replica Sigma Models

I survey the kinds of critical behavior believed to be exhibited in twodimensional disordered systems. I review the different replica sigma models used to describe the low-energy physics, and discuss how critical points appear because of WZW and theta terms.
Near-Constant-Time Distributed Algorithms on a Congested Clique

This paper presents constant-time and near-constant-time distributed algorithms for a variety of problems in the congested clique model. We show how to compute a 3-ruling set in expected O(logloglogn) rounds and using this, we obtain a constant-approximation to metric facility location, also in expected O(logloglogn) rounds. In addition, assuming an input metric space of constant doubling dimension, we obtain constant-round algorithms to compute constant-factor approximations to the minimum spanning tree and the metric facility location problems. These results significantly improve on the running time of the fastest known algorithms for these problems in the congested clique setting.
QB or Not QB: An Efficient Execution Verification Tool for Memory Orderings

We study the problem of formally verifying shared memory multiprocessor executions against memory consistency models—an important step during post-silicon verification of multiprocessor machines. We employ our previously reported style of writing formal specifications for shared memory models in higher order logic (HOL), obtaining intuitive as well as modular specifications. Our specification consists of a conjunction of rules that constrain the global visibility order. Given an execution to be checked, our algorithm generates Boolean constraints that capture the conditions under which the execution is legal under the visibility order. We initially took the approach of specializing the memory model HOL axioms into equivalent (for the execution to be checked) quantified boolean formulae (QBF). As this technique proved inefficient, we took the alternative approach of converting the HOL axioms into a program that generates a SAT instance when run on an execution. In effect, the quantifications in our memory model specification were realized as iterations in the program. The generated Boolean constraints are satisfiable if and only if the given execution is legal under the memory model. We evaluate two different approaches to encode the Boolean constraints, and also incremental techniques to generate and solve Boolean constraints. Key results include a demonstration that we can handle executions of realistic lengths for the modern Intel Itanium memory model. Further research into proper selection of Boolean encodings, incremental SAT checking, efficient handling of transitivity, and the generation of unsatisfiable cores for locating errors are expected to make our technique practical.
Complexity of mechanism design

The aggregation of conflicting preferences is a central problem in multiagent systems. The key difficulty is that the agents may report their preferences insincerely. Mechanism design is the art of designing the rules of the game so that the agents are motivated to report their preferences truthfully and a (socially) desirable outcome is chosen. We propose an approach where a mechanism is automatically created for the preference aggregation setting at hand. This has several advantages, but the downside is that the mechanism design optimization problem needs to be solved anew each time. Focusing-on settings where side payments are not possible, we show that the mechanism design problem is NP-complete for deterministic mechanisms. This holds both for dominantstrategy implementation and for Bayes-Nash implementation. We then show that if we allow randomized mechanisms, the mechanism design problem becomes tractable. In other words, the coordinator can tackle the computational complexity introduced by its uncertainty the agents face additional uncertainty. This comes at no loss, and in some cases at a gain, in the (social) objective.
Lowering the hydrogen desorption temperature of NH3BH3 through B-group substitutions

We present ab initio results for substitutions intended to lower the hydrogen desorption temperature of NH3BH3, a promising hydrogen-storage material. Substitutions have already been investigated with significant success recently, but in all cases a less electronegative element is substituted for the protic hydrogen in the NH3 group of NH3BH3. We propose a different route, substituting the hydridic hydrogen in the BH3 group with a more electronegative element. To keep the gravimetric density high, we focus on the second period elements C, N, O, and F, all with higher electronegativities compared to H. In addition, we investigate Cu and S as possible substitutions. Our main results include Bader charge analyses, hydrogen binding energies, and kinetic barriers for the hydrogen release reaction in the gas phase as well as in the solid. While the different substituents show varying effects on the kinetic barrier and desorption temperature, we identify Cu as a very promising substituent, which lowers the reaction barrier by approximately 38% compared to pure NH3BH3 resulting in a significantly reduced hydrogen desorption temperature.
Parallel Computations of Electron-Molecule Collisions in Processing Plasmas

In the plasmas used in semiconductor fabrication, collisions between electrons and polyatomic molecules produce reactive fragments that drive etching and other processes at the wafer surface. Extensive and reliable data on electron-molecule collisions are therefore essential to simulations of plasma reactors. For the low electron energies and polyatomic gases of interest, both measurements and calculations are difficult, and many needed cross sections are lacking. However, rapid advances in computer speeds now make such calculations feasible. Because the fastest computers are highly parallel, both a formulation that accounts well for the physics of low-energy collisions and an implementation that is efficient on parallel architectures are required. We will give an overview of our formulation of the electron-molecule collision problem and of its implementation and performance on parallel machines, and of some results of its application.
Fundamental Techniques for Order Optimization

This paper briefly describes some of the novel techniques used by the query optimizer of IBM's DB2 to process and optimize the way order requirements are satisfied.
On the uselessness of quantum queries

Given a prior probability distribution over a set of possible oracle functions, we define a number of queries to be useless for determining some property of the function if the probability that the function has the property is unchanged after the oracle responds to the queries. A familiar example is the parity of a uniformly random Boolean-valued function over {1,2,...,N}, for which N-1 classical queries are useless. We prove that if 2k classical queries are useless for some oracle problem, then k quantum queries are also useless. For such problems, which include classical threshold secret sharing schemes, our result also gives a new way to obtain a lower bound on the quantum query complexity, even in cases where neither the function nor the property to be determined is Boolean.
Large distance expansion of Mutual Information for disjoint disks in a free scalar theory

We compute the next-to-leading order term in the long-distance expansion of the mutual information for free scalars in three space-time dimensions. The geometry considered is two disjoint disks separated by a distance r between their centers. No evidence for non-analyticity in the Renyi parameter n for the continuation n → 1 in the next-to-leading order term is found.
Ten years after Morocco's family code reforms : are gender gaps closing?

In 2004, the Government of Morocco (GoM) made major amendments to its family code, known as the Moudawana, which covers personal status issues such as marriage, divorce, alimony, child support, child custody, and inheritance. These reforms increased the rights of women within the family, and should boost womens agency beyond family matters, for example increasing control of economic assets. The revisions followed a process of relatively open public debate with much of the discussion driven by womens civil society organizations (CSOs). It does suggest that women have made gains in determining who to marry, and are more able to access to divorce without renouncing their financial assets. On many other key issues, such as the use of stipulations in marriage contracts to increase women's decision-making within marriage and control of economic assets, as well as the extent to which community property regimes have been adopted by married couples, the lack of data prevents effective measurement of progress. Plans of the Ministry of Justice and Liberty to measure implementation of the Moudawana linked with the charter for the reform of the judicial system will hopefully provide the GoM a useful tool in ensuring further narrowing of gender equality gaps.
Mentoring: what is it? How do we do it and how do we get more of it?

Although mentoring is something most of us talk about doing and needing on a regular basis, it isn’t obvious what being a mentor means, precisely, or what the process of mentoring entails. Is it the same as training? teaching? advising? Is being a mentor the same as being a good role model? Are these all labels for the same thing? Having agreed to talk about mentoring at this event in honor of Harold Luft, I did what any good researcher of today would do——I googled the term. I discovered that there are a fair number of websites out there dedicated to the topic. The term is used by organizations that focus on youth mentoring, including an organization called Mentor that stresses ‘‘Expanding the world of quality mentoring,’’ as well as those promoting business mentoring, and, something more familiar to many of us, academic mentoring. Further evidence that this is a global concept, there’s even an International Mentoring Association. My search also revealed a large selection of books and articles with mentoring in the title (e.g., ‘‘Toward a Conceptualization of Mentoring,’’ Anderson and Shannon 1988) and even a software package offered by one business consulting firm called ‘‘Mentoring that Makes a Difference.’’ While not an exhaustive search, I was nonetheless amazed by the range of uses and lack of consensus out there about what mentoring is, much less how to do it and get
Spin crossover systems in the deep mantle

There has been much interest in spin crossovers found experimentally in the most abundant minerals of Earths lower mantle ((MgFe)O, (MgFe)(Si,Fe)O3-perovskite and postperovskite) under pressure. Spin crossovers depend strongly on thermodynamic conditions and a full understanding of this problem requires its investigation as function of pressure and temperature. Several aspects of this phenomenon have been difficult to understand based on experiments alone, especially in the perovskite system, and electronic structure calculations are helping to clarify them. The geophysical consequences of these crossovers are yet to be fully understood. I will review progress we have made in understanding spin crossovers and give an overview of this phenomenon and its potential implications for the Earth.
Slow and Go: Pulsing slip rates on the creeping section of the San Andreas Fault

Rising and falling slip rates on the creeping section of the San Andreas Fault have been inferred from variations of recurrence intervals of characteristically repeating microearthquakes, but this observation has not previously been confirmed using modern geodetic data. Here we report on observations of this “pulsing” slip obtained from advanced multitemporal interferometric synthetic aperture radar (InSAR) data, confirmed using continuous GPS sites of the Plate Boundary Observatory. The surface deformation time series show a strong correlation to the previously documented slip rate variations derived from repeating earthquakes on the fault interface, at various spatial and temporal scales. Time series and spectral analyses of repeating earthquake and InSAR data reveal a quasiperiodic pulsing with a roughly 2 year period along some sections of the fault, with the earthquakes on the fault interface lagging behind the far-field deformation by about 6 months. This suggests a temporal delay between the pulsing crustal strain generated by deep-seated shear and the time-variable slip on the shallow fault interface, and that at least in some places this process may be cyclical. There exist potential impacts for time-dependent seismic hazard forecasting in California and, as it becomes better validated in the richly instrumented natural laboratory of the central San Andreas Fault, the process used here will be even more helpful in characterizing hazard and fault zone rheology in areas without California's geodetic infrastructure.
CHARACTERIZING THE COOL KOIs. VIII. PARAMETERS OF THE PLANETS ORBITING KEPLER’S COOLEST DWARFS

The coolest dwarf stars targeted by the Kepler Mission constitute a relatively small but scientifically valuable subset of the Kepler target stars, and provide a high-fidelity, nearby sample of transiting planetary systems. Using archival Kepler data spanning the entire primary mission, we perform a uniform analysis to extract, confirm, and characterize the transit signals discovered by the Kepler pipeline toward M-type dwarf stars. We recover all but two of the signals reported in a recent listing from the Exoplanet Archive resulting in 163 planet candidates associated with a sample of 104 low-mass stars. We fitted the observed light curves to transit models using a Markov Chain Monte Carlo method and we have made the posterior samples publicly available to facilitate further studies. We fitted empirical transit times to individual transit signals with significantly non-linear ephemerides for accurate recovery of transit parameters and precise measuring of transit timing variations. We also provide the physical parameters for the stellar sample, including new measurements of stellar rotation, allowing the conversion of transit parameters into planet radii and orbital parameters.
Nonlinear frequency shift of electrostatic waves in general collisionless plasma: Unifying theory of fluid and kinetic nonlinearities

The nonlinear frequency shift is derived in a transparent asymptotic form for intense Langmuir waves in general collisionless plasma. The formula describes both fluid and kinetic effects simultaneously. The fluid nonlinearity is expressed, for the first time, through the plasma dielectric function, and the kinetic nonlinearity accounts for both smooth distributions and trapped-particle beams. Various known limiting scalings are reproduced as special cases. The calculation avoids differential equations and can be extended straightforwardly to other nonlinear plasma waves.
On the Optimality of Treating Interference as Noise: General Message Sets

In a $K$ -user Gaussian interference channel, it has been shown that if for each user the desired signal strength is no less than the sum of the strengths of the strongest interference from this user and the strongest interference to this user (all values in decibel scale), then treating interference as noise (TIN) is optimal from the perspective of generalized degrees of freedom (GDoF) and achieves the entire channel capacity region to within a constant gap. In this paper, we show that for such TIN-optimal interference channels, even if the message set is expanded to include an independent message from each transmitter to each receiver, operating the new channel as the original interference channel and treating interference as noise is still optimal for the sum capacity up to a constant gap. Furthermore, we extend the result to the sum-GDoF optimality of TIN in the general setting of $X$ channels with arbitrary numbers of transmitters and receivers.
Effective affirmative action in school choice

The prevalent affirmative action policy in school choice limits the number of admitted majority students to give minority students higher chances to attend their desired schools. There have been numerous efforts to reconcile affirmative action policies with celebrated matching mechanisms such as the deferred acceptance and top trading cycles algorithms. Nevertheless, it is theoretically shown that under these algorithms, the policy based on majority quotas may be detrimental to minorities. Using simulations, we find that this is a more common phenomenon rather than a peculiarity. To circumvent the inefficiency caused by majority quotas, we offer a different interpretation of the affirmative action policies based on minority reserves. With minority reserves, schools give higher priority to minority students up to the point that the minorities fill the reserves. We compare the welfare effects of these policies. The deferred acceptance algorithm with minority reserves Pareto dominates the one with majority quotas. Our simulations, which allow for correlations between student preferences and school priorities, indicate that minorities are, on average, better off with minority reserves while adverse effects on majorities are mitigated.
A uranyl sulfate cluster in Na10[(UO2)(SO4)4](SO4)2.3H2O.

Decasodium uranyl hexa­sulfate trihydrate, Na10[(UO2)(SO4)4](SO4)2·3H2O, contains an unusual uranyl sulfate cluster with the composition [(UO2)(SO4)4]6−. The cluster is composed of a uranyl pentagonal bipyramid and four sulfate tetrahedra. Three sulfate tetrahedra are linked to the uranyl pentagonal bipyramid by the sharing of vertices, and the other shares an equatorial edge of the uranyl pentagonal bipyramid. The uranyl sulfate clusters occur in layers parallel to (010). The structure also contains two isolated symmetrically distinct sulfate tetrahedra, which also occur in layers parallel to (010). The uranyl sulfate clusters and isolated sulfate tetrahedra are linked through bonds to Na+ cations, and by hydrogen bonding involving the water molecules.
On the coverage bound problem of empirical likelihood methods for time series

Summary. The upper bounds on the coverage probabilities of the confidence regions based on blockwise empirical likelihood and non-standard expansive empirical likelihood methods for time series data are investigated via studying the probability of violating the convex hull constraint. The large sample bounds are derived on the basis of the pivotal limit of the blockwise empirical log-likelihood ratio obtained under fixed b asymptotics, which has recently been shown to provide a more accurate approximation to the finite sample distribution than the conventional χ 2 -approximation. Our theoretical and numerical findings suggest that both the finite sample and the large sample upper bounds for coverage probabilities are strictly less than 1 and the blockwise empirical likelihood confidence region can exhibit serious undercoverage when the dimension of moment conditions is moderate or large, the time series dependence is positively strong or the block size is large relative to the sample size. A similar finite sample coverage problem occurs for non-standard expansive empirical likelihood.To alleviate the coverage bound problem, we propose to penalize both empirical likelihood methods by relaxing the convex hull constraint. Numerical simulations and data illustrations demonstrate the effectiveness of our proposed remedies in terms of delivering confidence sets with more accurate coverage. Some technical details and additional simulation results are included in on-line supplemental material.
Photolithography at wavelengths below 200 nm

Projection photolithography is widely expected to remain the main high-throughput patterning technology of microelectronic circuits in the next few years. As the critical dimensions of these devices shrink to 0.18 micrometers and below, the lithographic wavelength will decrease from 248 to 193 nm, and possible to 157 nm. This paper reviews the challenges posed by reducing the wavelength to below 200 nm, and the current state of the art in the critical areas of optical materials, photoresists, and high-resolution patterning.
Highly Selective Hydrolytic Kinetic Resolution of Terminal Epoxides Catalyzed by Chiral (salen)CoIII Complexes. Practical Synthesis of Enantioenriched Terminal Epoxides and 1,2-Diols

The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)CoIII complex 1·OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H2O as a reactant and low loadings (0.2−2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to ≥99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H2O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (krel) were determined ...
Enumeration of connected Catalan objects by type

Noncrossing set partitions, nonnesting set partitions, Dyck paths, and rooted plane trees are four classes of Catalan objects which carry a notion of type. There exists a product formula which enumerates these objects according to type. We define a notion of 'connectivity' for these objects and prove an analogous product formula which counts connected objects by type. Our proof of this product formula is combinatorial and bijective. We extend this to a product formula which counts objects with a fixed type and number of connected components. We relate our product formulas to symmetric functions arising from parking functions. We close by presenting an alternative proof of our product formulas communicated to us by Christian Krattenthaler (2010) [7] which uses generating functions and Lagrange inversion.
An advanced showcase of adaptive controller designs

The adaptive control literature contains numerous theories for deriving adaptive controllers. However, practising engineers who are not specialists in adaptive theory often have difficulty selecting which approach to use in a given application. The papers in this special issue address this situation by defining a set of standard problems which are then solved by several distinct adaptive control approaches. This introductory paper provides the motivation for the issue (why it is important, who is the target audience, what is the goal of the process), defines the standard problems to be considered and explains the rationale for their formulation, and describes the guidelines which were established for the participants. In addition, this paper defines the ‘ideal’ closed-loop responses for each standard problem, from which the results of the subsequent papers can be judged.
Improving Wellbore Position Accuracy of Horizontal Wells by Using A Continuous Inclination Measurement From a Near Bit Inclination MWD Sensor

Wellbore position calculations are typically performed by measuring Azimuth and Inclination at 10 to 30 meter intervals and using interpolation techniques to determine the borehole position between the survey stations. Input parameters are Measured Depth (MD), Azimuth and Inclination, where the latter two parameters are measured with the MWD tool, in a stationary mode (non-rotating). Output parameters are the geometric co-ordinates;True Vertical Depth (TVD), North and East. To maximise the exposure of a production well to the reservoir, horizontal wellbores are frequently being drilled. Furthermore, to maximise the production of hydrocarbons from these wells, their relative position within the reservoir is critical. Improving the accuracy of the Inclination measurement and thus reducing the uncertainty of the calculated TVD value will increase the confidence in wellbore position. The NaviGator geosteering tool or the Auto Trak rotary steerable system are frequently used to optimise the position of horizontal wellbores within the reservoir. Both these geosteering tools use a Near Bit Inclination sensor (NBI) to help the directional driller perform directional changes smoothly and accurately. Unlike traditional directional sensors the NBI sensor is capable of accurately measuring inclination while being rotated. Consequently NBI measurements can be performed continuously during drilling. The measurements can be used to more accurately calculate the wellbore trajectory. Results in the paper demonstrate that the NBI sensor is more accurately measuring inclination than other directional sensors in a horizontal well. Also, by continuously measuring the inclination during rotation, some error sources are reduced, resulting in improved TVD accuracy.
Lipschitz constants to curve complexes

We determine the asymptotic behavior of the optimal Lipschitz constant for the systole map from Teichmuller space to the curve complex.
Simple solutions to the initial conditions problem in dynamic, nonlinear panel data models with unobserved heterogeneity

I study a simple, widely applicable approach to handling the initial conditions problem in dynamic, nonlinear unobserved effects models. Rather than attempting to obtain the joint distribution of all outcomes of the endogenous variables, I propose finding the distribution conditional on the initial value (and the observed history of strictly exogenous explanatory variables). The approach is flexible, and results in simple estimation strategies for at least three leading dynamic, nonlinear models: probit, Tobit and Poisson regression. I treat the general problem of estimating average partial effects, and show that simple estimators exist for important special cases. Copyright © 2005 John Wiley & Sons, Ltd.
"PACTOLUS": a digital analog simulator program for the IBM 1620

Perhaps the most formidable challenge in the field of digital computer applications is the development of equipment and programs which will extend the creative power of scientific users. The crux of the problem, of course, is intimate man-machine communication---a most elusive and difficult-to-define characteristic. The engineer requires a conveniently manageable system; the scientist requires sufficient intimacy to provide real insight into the complex interplay of problem variables; the creative user requires computing power and flexibility to permit imaginative use of the computer and graphic display to permit recognition of inventive solutions. The development of computers designed specifically for such applications has been slow due to the difficulty of ascertaining the proper man-machine relationship.
Complex social contagion makes networks more vulnerable to disease outbreaks

Social network analysis is now widely used to investigate the dynamics of infectious disease spread. Vaccination dramatically disrupts disease transmission on a contact network, and indeed, high vaccination rates can potentially halt disease transmission altogether. Here, we build on mounting evidence that health behaviors - such as vaccination, and refusal thereof - can spread across social networks through a process of complex contagion that requires social reinforcement. Using network simulations that model health behavior and infectious disease spread, we find that under otherwise identical conditions, the process by which the health behavior spreads has a very strong effect on disease outbreak dynamics. This dynamic variability results from differences in the topology within susceptible communities that arise during the health behavior spreading process, which in turn depends on the topology of the overall social network. Our findings point to the importance of health behavior spread in predicting and controlling disease outbreaks.
An intense clinicopathologic study of 305 teratomas of the ovary

A 20-year retrospective review of 305 consecutive ovarian teratomas diagnosed in the surgical pathology department of the Kings County Hospital is presented. All but 10 cases represented the benign cystic variety of this tumor. One case of benign solid ovarian teratoma and 9 cases of malignant ovarian teratomas were also encountered. The laterality, age incidence, size, and gross and microscopic description of these tumors are discussed in considerable detail, as is the distribution of structures found within the benign cystic variety. Brief mention also is made regarding the incidence of struma ovarii, pregnancy, torsion, intraperitoneal rupture, and coincidental lesions found in association with ovarian teratomas.
The Amplitude of Mass Fluctuations

We determine the linear amplitude of mass fluctuations in the universe, σ8, from the abundance of massive clusters at redshifts z = 0.5-0.8. The evolution of massive clusters depends exponentially on the amplitude of mass fluctuations and thus provides a powerful measure of this important cosmological parameter. The relatively high abundance of massive clusters observed at z > 0.5 and the relatively slow evolution of their abundance with time suggest a high amplitude of mass fluctuations: σ8 = 0.9 (±10%) for Ωm = 0.4, increasing slightly to σ8 = 0.95 for Ωm = 0.25 and σ8 = 1.0 for Ωm = 0.1 (flat cold dark matter models). We use the cluster abundance observed at z = 0.5-0.8 to derive a normalization relation from the high-redshift clusters, which is only weakly dependent on Ωm: σ8Ω = 0.78 ± 0.08. When combined with recent constraints from the present-day cluster mass function, σ8Ω = 0.33 ± 0.03, we find σ8 = 0.98 ± 0.1 and Ωm = 0.17 ± 0.05. Low-σ8 values (0.7) are unlikely; they produce an order-of-magnitude fewer massive clusters than observed.
Monopoly and trade policy

Abstract This paper derives trade policy rankings for a country trading with a foreign monopoly firm. It characterizes the first-best policy under decreasing monopoly costs, and itdemonstrates that a minimum import requirement implements first-best trade only under constant monopoly costs. The paper shows further that a voluntary import expansion eliminates all gains from trading with the monopoly, and that all quotas and voluntary export restraints are equivalent. Finally, it establishes that a price ceiling and a minimum import requirement are equivalent when monopoly costs are constant or decreasing, but that their ranking is ambiguous when costs are increasing.
Cosmic Chemical Evolution

Numerical simulations of standard cosmological scenarios have now reached the degree of sophistication required to provide tentative answers to the fundamental question: Where and when were the heavy elements formed? Averaging globally, these simulations give a metallicity that increases from 1% of the solar value at z = 3 to 20% at present. This conclusion is, in fact, misleading, as it masks the very strong dependency of metallicity on local density. At every epoch, higher density regions have much higher metallicity than lower density regions. Moreover, the highest density regions quickly approach near-solar metallicity and then saturate, while more typical regions slowly catch up. These results are much more consistent with observational data than the simpler picture (adopted by many) of gradual, quasi-uniform increase of metallicity with time.