cssi/SciSciGPT-SciSciNet huggingface dataset:
Navigation capability for an ion drive rendezvous with Halley's Comet

An analysis has been conducted in connection with plans for a study of Halley's Comet during its 1986 apparition. The use of low-thrust vehicles, utilizing an ion drive system, is being considered for a comet rendezvous mission. A preliminary trajectory for the Halley rendezvous mission calls for launch on June 20, 1982, followed by rendezvous on December 21, 1985. The navigation analysis described focuses on the terminal approach to Halley, the 60-day period preceding rendezvous. Navigation analysis assumptions are examined, taking into account navigation error sources, radio tracking, onboard optical data, earth-based comet observations, and orbit determination and guidance strategies. The preliminary mission design considers a rendezvous at approximately 56,000 km from the comet nucleus (6,000 km outside the dust envelope). Navigation performance is measured in terms of comet-relative position and velocity errors at encounter. Variations to the baseline navigation study provide illustrations concerning the close link between delivery accuracy and stochastic thrust errors.
The algebra of events

A number of writers have commented on the close parallels between the mass-count distinction in nominal systems and the aspectual classification of verbal expressions (Allen, 1966; Mourelatos, 1978; L. Carlson, 1981; Hoepelman and Rohrer, 1980) that has been the subject of much attention in recent years in linguistics and philosophy. To take just one class of examples for now, there is a parallel between the two sets of distinctions in their cooccurrence patterns with expressions denoting numbers or amounts, as in Examples (1a)–(4b):
Logical inference algorithms and matrix representations for probabilistic conditional independence

Logical inference algorithms for conditional independence (CI) statements have important applications from testing consistency during knowledge elicitation to constraint-based structure learning of graphical models. We prove that the implication problem for CI statements is decidable, given that the size of the domains of the random variables is known and fixed. We will present an approximate logical inference algorithm which combines a falsification and a novel validation algorithm. The validation algorithm represents each set of CI statements as a sparse 0--1 matrix A and validates instances of the implication problem by solving specific linear programs with constraint matrix A. We will show experimentally that the algorithm is both effective and efficient in validating and falsifying instances of the probabilistic CI implication problem.
Uniqueness of Symplectic Canonical Class, Surface Cone and Symplectic Cone of 4-Manifolds with B+ = 1

Let M be a closed oriented smooth 4-manifold admitting symplectic structures. If M is minimal and has b+ = 1, we prove that there is a unique symplectic canonical class up to sign, and any real second cohomology class of positive square is represented by symplectic forms. Similar results hold when M is not minimal.
Effect of electronic-ballast fluorescent lighting on wireless infrared links

Fluorescent lamps driven by electronic ballasts emit an infrared (IR) signal that is periodically modulated at rates of tens of kilohertz, and which can severely impair the performance of IR wireless links. The impact of fluorescent interference can potentially be reduced by high-pass electrical filtering, but such filtering induces intersymbol interference (ISI). We present expressions for the bit-error rate (BER) of systems using on-off keying (OOK) and pulse-position modulation (PPM) in the presence of both a deterministic interfering signal and ISI. We evaluate the performance of IR links using OOK and 2-, 4-, 8-, and 16-PPM at bit rates of 1, 10, and 100 Mb/s. The penalties incurred by OOK are found to be essentially independent of bit rate. At 1 Mb/s, PPM suffers approximately the same penalties as OOK, but as the bit rate is increased, the degradation of PPM becomes progressively much smaller In the absence of measures to prevent ISI, first-order highpass filtering is not effective in improving the performance of OOK, but can substantially improve PPM link performance at bit rates of 10 and 100 Mb/s.
Declarative mediation in distributed systems

The mediation architecture is widely used for bridging heterogeneous data sources. We investigate how such architecture can be extended to embrace information processing services and suggest a framework that supports declarative specification of mediation logic. In this paper we show how our framework can be applied to enrich interface descriptions of distributed objects and to integrate them with other client/server environments.
Discrete Choice Modeling

We detail the basic theory for models of discrete choice. This encompasses methods of estimation and analysis of models with discrete dependent variables. Entry level theory is presented for the practitioner. We then describe a few of the recent, frontier developments in theory and practice.
THE DYNAMICS OF QUOTED LIQUIDITY AROUND LARGE TRADES ON THE NYSE

Large trades have potentially disruptive effects on the continuation of subsequent trade. If the large trade executes against volume from limit orders or specialist quotations, continued trade may be unavailable until new liquidity enters the market. Evidence presented in this paper indicates that large trades on the NYSE are followed by decreases in quoted liquidity, which last for an average of fifteen minutes. Both the decreases in quoted liquidity and the time to its subsequent return are related to trade-specific factors. This evidence suggests that not all large trades have the same effect on the continuation of trade.
Nonlinear MHD instabilities in elongated cylinders

We have studied the nonlinear evolution of fixed-boundary instabilities using a 3-D ideal-MHD computer simulation. Here, we concentrate on the effect of elongation and peaked profile. It is found that the dominant process is convection around essentially fixed velocity vortex cells.
Official Knowledge: Democratic Education in a Conservative Age

1. Introduction: The Politics of Official Knowledge 2. The Politics of Common-sense: Why the Right is Winning 3. Cultural Politics and the Text 4. Regulating Official Knowledge 5. Creating the Captive Audience: Channel One and the Political Economy of the Text 6. Whose Curriculum is This Anyway? (with Susan Jungck) 7. Hey Man, I'm Good! The Art and Politics of Creating New Knowledge in Schools 8. The Politics of Pedagogy and the Building of Community Appendix Education, Power, and Personal Biography: An Interview.
Production, sales, and the change in inventories ☆: An identity that doesn't add up

We examine two measures of monthly manufacturing production. The first is the index of industrial production; the second is constructed from the accounting identity that output equals sales plus the change in inventories. We show that the means, variances, and serial correlation coefficients of the log growth rates differ substantially between the two series, and the cross-correlations are in most cases less than 0.4. A model of classical measurement error indicates that in 15 of 20 two-digit industries measurement error accounts for over 35% of the variation in the monthly growth rates of seasonally adjusted industrial production.
A dynamic polariscope for stress wave analysis

A polariscope for the study of the propagation of stress waves in birefringent sheets is described. Sensitive, fast-responding photomultiplier tubes, a laser light source, and a multiple channel oscilloscope were used for the simultaneous recording of the stress-optic data at several points of the target following impact. A method of separation of stresses and the computation of displacement, strain, and stress is given.
Antidumping in law and practice

The alarming increase in the number of antidumping actions pursued by both industrial and developing countries has caused considerable concern among economists, lawyers, and trade reformers. These concerns have led to suggestions to substitute antitrust principles for antidumping laws and regulations or to use safeguard measures under Article XIX of GATT 1994 and the Uruguay Round Agreement on Safeguards. The author contends that, under current international trade law, neither proposal appears feasible. Moreover, antidumping actions have become a fact of life and the international community recognizes them as the only legitimate tool to combat dumping as defined by and determined in accordance with law. Despite urgings in some quarters, neither national legal systems nor international agreements have mandated an economy-wide cost-benefit analysis of proposed antidumping actions. Because of political, technical, and other implications, such a methodology is unlikely to be accepted soon. Although the most recent Uruguay Round antidumping agreement (URAA) has enhanced the discipline and made a number of improvements, it cannot claim to have plugged all loopholes for the misuse of antidumping. In those matters on which the agreement is silent or ambiguous or allows room for flexibility in adopting a less restrictive rule or practice. A case in point is the U.S. practice on voting in the International Trade Commission. A 3-3 vote in antidumping and countervailing duty investigation constitutes an affirmative decision. It would be preferable to require a clear majority rather than treat an evenly divided vote as sufficient to establish a finding of injury.
Forecasting local climate for policy analysis : a pilot application for Ethiopia

This paper describes an approach to forecasting future climate at the local level using historical weather station and satellite data and future projections of climate data from global climate models (GCMs) that is easily understandable by policymakers and planners. It describes an approach to synthesize the myriad climate projections, often with conflicting messages, into an easily-interpreted set of graphical displays that summarizes the basic implications of the ensemble of available climate models. The method described in the paper can be applied to publicly-available data for any country and for any number of climate models. It does not depend on geographic scale and can be applied at the subnational, national, or regional level. The paper illustrates the results for future climate for Ethiopia using future climate scenarios projects by 8 global climate models. The graphical displays of nine possible future climate regimes (average temperature, precipitation and their seasonal distribution) for each grid-cell about 50km X 50 km). It also provides the probability associated with each of the nine-climate regimes.
Physics in Very Strong Magnetic Fields

This paper provides an introduction to a number of astrophysics problems related to strong magnetic fields. The first part deals with issues related to atoms, condensed matter and high-energy processes in very strong magnetic fields, and how these issues influence various aspects of neutron star astrophysics. The second part deals with classical astrophysical effects of magnetic fields: Even relatively “weak” fields can play a strong role in various astrophysical problems, ranging from stars, accretion disks and outflows, to the formation and merger of compact objects.
Triangulations of $\Delta_{n-1} \times \Delta_{d-1}$ and Tropical Oriented Matroids

Develin and Sturmfels showed that regular triangulations of $\Delta_{n-1} \times \Delta_{d-1}$ can be thought of as tropical polytopes. Tropical oriented matroids were defined by Ardila and Develin, and were conjectured to be in bijection with all subdivisions of $\Delta_{n-1} \times \Delta_{d-1}$. In this paper, we show that any triangulation of $\Delta_{n-1} \times \Delta_{d-1}$ encodes a tropical oriented matroid. We also suggest a new class of combinatorial objects that may describe all subdivisions of a bigger class of polytopes.
Computing Zeta Functions via p-Adic Cohomology

We survey some recent applications of p-adic cohomology to machine computation of zeta functions of algebraic varieties over finite fields of small characteristic, and suggest some new avenues for further exploration.
A quantum-dot array as model for copper-oxide superconductors: A dedicated quantum simulator for the many-fermion problem

Quantum systems with a large number of fermionic degrees of freedom are intractable by quantum simulations. In this paper we introduce the concept of a dedicated quantum simulator (DQS) which is an artificial system of quantum dots whose Hamiltonian maps exactly to the original many fermion problem. While the universal quantum simulator (UQS) introduced by Feynman in 1982 can simulate any quantum mechanical many-body problem, a DQS can only solve a particular many body problem. Our concept of the dedicated quantum simulator is not a quantum computer but rather a quantum “analog” device, dedicated to a particular quantum computation. As an example, we consider the system of the CuO plane in the copper-oxide superconductors and we propose an array of electrostatically confined quantum dots to be used as its dedicated quantum simulator. We show that this dedicated device can be used to image stripe formation as a function of the electron doping using electric force microscopy. We argue that such a dedicated quantum simulator may be easier to realize in the future compared to a general purpose quantum computer.
Next best view algorithms for interior and exterior model acquisition

Rapid determination of optimal laser range finder placement is becoming of increased importance in both computer vision and robotics. The need of next-best-view algorithms for intelligent decisions in where to place the laser range finder is important for scanning both objects and landscapes to assure that the scene is fully realized and can be registered accurately. Presented here are methods for determining sensor placement to maximize the amount of information that is learned about a scene or object. Using occupancy grids of voxels and ray tracing, the placement of the sensor can be optimized for maximum collection of new data. This work provides fast algorithms that determine optimal sensor placement both outside an object of interest and inside of a closed environment. These methods take into consideration the limitations of the sensor, the interaction of the sensor to the environment, and its placement in only known areas to restrict the search space.
CUP: Controlled Update Propagation in Peer-to-Peer Networks.

This paper proposes CUP, a protocol for performing Controlled Update Propagation to maintain caches of metadata in peer-to-peer networks. To moderate propagation without imposing a global policy, CUP introduces the notion of individual node investment return. CUP allows each node to determine when it has economic incentive to receive and to propagate updates. A node participates in propagation only when the benefit (investment return) it secures from receiving and propagating updates outweighs its cost of propagation. We extensively evaluate the CUP protocol in maintaining caches of metadata for locating content in peerto-peer networks. We demonstrate that propagation of updates reduces the average latency of content search queries by as much as an order of magnitude across a variety of workloads. We propose and evaluate the use of popularity-based incentives to drive a node’s propagation policy. These include incentives based on probabilistic as well as history-based models of investment return. Using these policies, we show that CUP nodes recover their propagation overhead by a factor of 2 to 300, thus offering a lean but powerful protocol.
Unbiased Estimate of Dark Energy Density from Type Ia Supernova Data

Type Ia supernovae (SNe Ia) are currently the best probes of the dark energy in the universe. To constrain the nature of dark energy, we assume a flat universe and that the weak energy condition is satisfied, and we allow the density of dark energy, ρX(z), to be an arbitrary function of redshift. Using simulated data from a space-based SN pencil-beam survey, we find that by optimizing the number of parameters used to parameterize the dimensionless dark energy density, f(z) = ρX(z)/ρX(z = 0), we can obtain an unbiased estimate of both f(z) and the fractional matter density of the universe, Ωm. A plausible SN pencil-beam survey (with a square degree field of view and for an observational duration of 1 yr) can yield about 2000 SNe Ia with 0 ≤ z ≤ 2. Such a survey in space would yield SN peak luminosities with a combined intrinsic and observational dispersion of σ(mint) = 0.16 mag. We find that for such an idealized survey, Ωm can be measured to 10% accuracy, and the dark energy density can be estimated to ~20% to z ~ 1.5, and ~20%-40% to z ~ 2, depending on the time dependence of the true dark energy density. Dark energy densities that vary more slowly can be more accurately measured. For the anticipated Supernova/Acceleration Probe (SNAP) mission, Ωm can be measured to 14% accuracy, and the dark energy density can be estimated to ~20% to z ~ 1.2. Our results suggest that SNAP may gain much sensitivity to the time dependence of the dark energy density and Ωm by devoting more observational time to the central pencil-beam fields to obtain more SNe Ia at z > 1.2. We use both a maximum likelihood analysis and a Monte Carlo analysis (when appropriate) to determine the errors of estimated parameters. We find that the Monte Carlo analysis gives a more accurate estimate of the dark energy density than the maximum likelihood analysis.
Fused Lasso Additive Model

We consider the problem of predicting an outcome variable using p covariates that are measured on n independent observations, in a setting in which additive, flexible, and interpretable fits are desired. We propose the fused lasso additive model (FLAM), in which each additive function is estimated to be piecewise constant with a small number of adaptively-chosen knots. FLAM is the solution to a convex optimization problem, for which a simple algorithm with guaranteed convergence to a global optimum is provided. FLAM is shown to be consistent in high dimensions, and an unbiased estimator of its degrees of freedom is proposed. We evaluate the performance of FLAM in a simulation study and on two data sets. Supplemental materials are available online, and the R package flam is available on CRAN.
Dynamic Simulation of the Effect of Tamper Resistance on Opioid Misuse Outcomes

The objective of the study was to develop a system dynamics model of the medical use of pharmaceutical opioids, and the associated diversion and nonmedical use of these drugs. The model was used to test the impact of the a tamper resistance intervention in this complex system. The study relied on secondary data obtained from the literature and from other public sources for the period 1995 to 2008. In addition, an expert panel provided recommendations regarding model parameters and model structure. The behavior of the resulting systems-level model compared favorably with reference behavior data. After the base model was tested, logic to simulate the replacement of all opioids with tamper resistant formulations was added and the impact on overdose deaths was evaluated over a seven-year period, 2008-2015. Principal findings were that the introduction of tamper resistant formulations unexpectedly increased total overdose deaths. This was due to increased prescribing which counteracted the drop in the death rate. We conclude that it is important to choose metrics carefully, and that the system dynamics modelling approach can help to evaluate interventions intended to ameliorate the adverse outcomes in the complex system associated with treating pain with opioids.
A hybrid battery model capable of capturing dynamic circuit characteristics and nonlinear capacity effects

Summary form only given. A high-fidelity battery model capable of accurately predicting battery performance is required for proper design and operation of battery-powered systems. However, the existing battery models have at least one of the following drawbacks: 1) requiring intensive computation due to high complexity, 2) not applicable for electrical circuit design and simulation, and 3) not capable of accurately capturing the state of charge (SOC) and predicting runtime of the battery due to neglecting the nonlinear capacity effects. This paper proposes a novel hybrid battery model, which takes the advantages of an electrical circuit battery model to accurately predicting the dynamic circuit characteristics of the battery and an analytical battery model to capturing the nonlinear capacity effects for accurate SOC tracking and runtime prediction of the battery. The proposed battery model is validated by simulation and experimental studies for single-cell and multicell polymer lithium-ion batteries as well as for a lead-acid battery. The proposed model is applicable to other types and sizes of electrochemical battery cells. The proposed battery model is computational effective for simulation, design, and real-time management of battery-powered systems.
A middleware-based application framework for active space applications

Ubiquitous computing challenges the conventional notion of a user logged into a personal computing device, whether it is a desktop, a laptop, or a digital assistant. When the physical environment of a user contains hundreds of networked computer devices each of which may be used to support one or more user applications, the notion of personal computing becomes inadequate. Further, when a group of users share such a physical environment, new forms of sharing, cooperation and collaboration are possible and mobile users may constantly change the computers with which they interact; we refer to these digitally augmented physical spaces as Active Spaces. We present in this paper an application framework that provides mechanisms to construct, run or adapt existing applications to ubiquitous computing environments. The framework binds applications to users, uses multiple devices simultaneously, and exploits resource management within the users' environment that reacts to context and mobility. Our research contributes to application mobility, partitioning and adaptation within device rich environments, and uses context-awareness to focus the resources of ubiquitous computing environments on the needs of users.
On the Simulation of Heterogeneous Petroleum Reservoirs

The authors and coworkers have proposed the front tracking method as useful in applications to petroleum reservoir simulation. A variety of tests of a numerical analysis nature were performed for the method, verifying convergence under mesh refinement and absence of mesh orientation effects. The ability to handle complex interface bifurcation, fingering instabilities and polymer injection (as an example of tertiary oil recovery) indicates a level of robustness in this method. The main purpose of this paper is to report on two features which will allow further series of tests by enabling a more realistic description of reservoir heterogeneities. 29 refs., 4 figs.
Stripping efficiencies for 277 MeV/amu gold beam on copper foils

Stripping efficiencies were measured for 277 MeV/amu Au/sup 33+/ ions with copper foils ranging in thickness from 25 /spl mu/m to 100 /spl mu/m. The charge state distribution was analyzed using the beam line magnets of the transfer line between the AGS Booster and the AGS at Brookhaven. The relative charge state abundances were analyzed to find the optimum foil thicknesses for fully stripped Au/sup 79+/ and helium-like Au/sup 77+/. It was also possible to extract electron stripping and pick-up cross sections. >
Projective Dynamics in Realistic Models of Nanomagnets

The free-energy extrema governing the magnetization-reversal process for a model of an iron nanopillar are investigated using the projective dynamics method. Since the time evolution of the model is computationally intensive, one could question whether sufficient statistics can be generated, with current resources, to evaluate the position of the metastable configuration. Justification for the fine-grained discretization of the model that we use here is given, and it is shown that tractable results can be obtained for this system on realistic time scales.
Quire: lightweight provenance for smart phone operating systems

Smartphone apps are often granted to privilege to run with access to the network and sensitive local resources. This makes it difficult for remote endpoints to place any trust in the provenance of network connections originating from a user's device. Even on the phone, different apps with distinct privilege sets can communicate with one another. This can allow one app to trick another into improperly exercising its privileges (resulting in a confused deputy attack). In Quire, we engineered two new security mechanisms into Android to address these issues. First, Quire tracks the call chain of on-device IPCs, allowing an app the choice of operating with the reduced privileges of its callers or exercising its full privilege set by acting explicitly on its own behalf. Second, a lightweight signature scheme allows any app to create a signed statement that can be verified by any app on the same phone. Both of these mechanisms are reflected in network RPCs. This allows remote systems visibility into the state of the phone when the RPC was made. We demonstrate the usefulness of Quire with two example applications: an advertising service that runs advertisements separately from their hosting applications, and a remote payment system. We show that Quire's performance overhead is minimal.
Applications of the CRISPR–Cas9 system in cancer biology

The prokaryotic type II CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated 9) system is rapidly revolutionizing the field of genetic engineering, allowing researchers to alter the genomes of a large range of organisms with relative ease. Experimental approaches based on this versatile technology have the potential to transform the field of cancer genetics. Here, we review current approaches for functional studies of cancer genes that are based on CRISPR-Cas, with emphasis on their applicability for the development of next-generation models of human cancer.
Why did Sudicky [1986] find an exponential‐like spatial correlation structure for hydraulic conductivity at the Borden research site?

[1] The exponential-like spatial correlation structure for hydraulic conductivity that Sudicky (1986) found at the Borden research site arises from hierarchical sedimentary architecture. The sediments can be described in terms of a hierarchy of stratal unit types wherein larger-scale unit types (hierarchical level II) are composed of smaller-scale unit types (hierarchical level I). There is a hierarchy of permeability populations corresponding to this stratal hierarchy. The shape and effective range of the composite semivariogram is mostly defined by how the proportion of lag transitions crossing these unit types grows as a function of lag distance. Lag transitions across level I units but within the same level II unit type and transitions across level II unit types contribute about equally in defining the composite sample semivariogram in the vertical direction. These two types of cross transitions have shorter and longer length scales, respectively. The composite semivariogram reflects additive contributions from the two length scales. The proportion of cross-transition lags grows with an exponential-like curve because the unit types at either level reoccur with a relatively high variability in length. The shape and range of the semivariogram are modeled from knowing only the univariate statistics for length among the unit types, and the sill is modeled from knowing univariate statistics for hydraulic conductivity populations among the unit types. Understanding the relationship between the semivariogram structure and these quantifiable attributes of the hierarchical stratal architecture helps in reducing the equivocal aspects of choosing a semivariogram model. It also helps in identifying bias in sample semivariograms and in assessing stationarity of second-order spatial bivariate statistics.
Environmental Law and Policy

This casebook emphasizes environmental policy, as well as the structure and details of the federal environmental statutes. It focuses students' attention on how tradeoffs between environmental goals and social goals are resolved in different and difficult contexts. The book pays close attention to the political context in which regulation takes place, looking at the impact of federal government, interest groups, and administrative agencies in the regulatory process. It examines current efforts to address climate change and regulate greenhouse gases through existing statutory frameworks. The casebook includes substantial introductions and extensive notes and questions to guide classroom discussion. The book has been updated primarily to underscore the importance of the regulation of greenhouse gases under the Clean Air Act.
Using the X-FEL to Understand X-Ray Thomson Scattering for Partially Ionized Plasmas

For the last decade numerous researchers have been trying to develop experimental techniques to use X-ray Thomson scattering as a method to measure the temperature, electron density, and ionization state of high energy density plasmas such as those used in inertial confinement fusion. X-ray laser sources have always been of interest because of the need to have a bright monochromatic X-ray source to overcome plasma emission and eliminate other lines in the background that complicate the analysis. With the advent of the X-ray free electron laser (X-FEL) at the SLAC Linac Coherent Light Source (LCLS) we now have such a source available in the keV regime. Other X-FEL sources are being built in Germany and around the world. One challenge with X-ray Thomson scattering experiments is understanding how to model the scattering for partially ionized plasmas. Most Thomson scattering codes used to model experimental data greatly simplify or neglect the contributions of the bound electrons to the scattered intensity. In this work we take the existing models of Thomson scattering that include elastic ion-ion scattering and the electron-electron plasmon scattering and add the contribution of the bound electrons in the partially ionized plasmas. Except for hydrogen plasmas almost every plasma that is studied today has bound electrons and it is important to understand their contribution to the Thomson scattering, especially as new X-ray sources such as the X-FEL will allow us to study much higher Z plasmas. Currently most experiments have looked at hydrogen or beryllium. We will first look at the bound electron contributions to beryllium by analyzing existing experimental data. We then consider several higher Z materials such as Cr and predict the existence of additional peaks in the scattering spectrum that requires new computational tools to understand. For a Sn plasma we show that the bound contributions changes the shape of the scattered spectrum in a way that would change the plasma temperature and density inferred by the experiment.
Hadron resonance probes of QGP

We discuss the indirect and direct role of the short-lived resonances as probes of QGP freeze-out process. The indirect effect is the distortion of stable single particle yields and spectra by contributions of decaying resonances, which alter significantly the parameters obtained in fits to experimental data. We then discuss the direct observation of short-lived resonances as a probe of post-hadronization dynamics allowing to distinguish between different hadronization models.
On the ground validation of online diagnosis with Twitter and medical records

Social media has been considered as a data source for tracking disease. However, most analyses are based on models that prioritize strong correlation with population-level disease rates over determining whether or not specific individual users are actually sick. Taking a different approach, we develop a novel system for social-media based disease detection at the individual level using a sample of professionally diagnosed individuals. Specifically, we develop a system for making an accurate influenza diagnosis based on an individual's publicly available Twitter data. We find that about half (17/35 = 48.57%) of the users in our sample that were sick explicitly discuss their disease on Twitter. By developing a meta classifier that combines text analysis, anomaly detection, and social network analysis, we are able to diagnose an individual with greater than 99% accuracy even if she does not discuss her health.
Poverty Lines across the World

National poverty lines vary greatly across the world, from under $1 per person per day to over $40 (at 2005 purchasing power parity). What accounts for these huge differences, and can they be understood within a common global definition of poverty? For all except the poorest countries, the absolute, nutrition-based, poverty lines found in practice tend to behave more like relative lines, in that they are higher for richer countries. Prevailing methods of setting absolute lines allow ample scope for such relativity, even when nutritional norms are common across countries. Both macro data on poverty lines across the world and micro data on subjective perceptions of poverty are consistent with a weak form of relativity that combines absolute consumption needs with social-inclusion needs that are positive for the poorest but rise with a countrys mean consumption. The strong form of relativism favored by some developed countries -- whereby the line is set at a fixed proportion of the mean -- emerges as the limiting case for very rich countries.
The Goldstone equivalence theorem and AdS/CFT

The Goldstone equivalence theorem allows one to relate scattering amplitudes of massive gauge fields to those of scalar fields in the limit of large scattering energies. We generalize this theorem under the framework of the AdS/CFT correspondence. First, we obtain an expression of the equivalence theorem in terms of correlation functions of creation and annihilation operators by using an AdS wave function approach to the AdS/CFT dictionary. It is shown that the divergence of the non-conserved conformal current dual to the bulk gauge field is approximately primary when computing correlators for theories in which the masses of all the exchanged particles are sufficiently large. The results are then generalized to higher spin fields. We then go on to generalize the theorem using conformal blocks in two and fourdimensional CFTs. We show that when the scaling dimensions of the exchanged operators are large compared to both their spins and the dimension of the current, the conformal blocks satisfy an equivalence theorem.
Numerical Method for Darcy Flow Derived Using Discrete Exterior Calculus

We derive a numerical method for Darcy flow, and also for Poisson’s equation in mixed (first order) form, based on discrete exterior calculus (DEC). Exterior calculus is a generalization of vector calculus to smooth manifolds and DEC is one of its discretizations on simplicial complexes such as triangle and tetrahedral meshes. DEC is a coordinate invariant discretization, in that it does not depend on the embedding of the simplices or the whole mesh. We start by rewriting the governing equations of Darcy flow using the language of exterior calculus. This yields a formulation in terms of flux differential form and pressure. The numerical method is then derived by using the framework provided by DEC for discretizing differential forms and operators that act on forms. We also develop a discretization for a spatially dependent Hodge star that varies with the permeability of the medium. This also allows us to address discontinuous permeability. The matrix representation for our discrete non-homogeneous Hodge s...
M-Theory and Cosmology

This is a series of lectures on M-theory for cosmologists. After summarizing some of the main properties of M-theory and its dualities I show how it can be used to address various fundamental and phenomenological issues in cosmology.
Improving the Lives of the Poor through Investment in Cities: An Update on the Performance of the World Bank's Urban Portfolio

Cities are home to 525 million poor people, and the World Bank makes substantial investments in developing country cities every year. This study reviews the performance of 99 urban development operations completed since 1993 to see, in particular, how these interventions have improved the living conditions of the urban poor, the primary goal of the livability pillar of the World Bank's current urban strategy. Improving the Lives of Poor People by Investing in Cities finds that cities, who hosted World Bank supported urban projects, improved their livability conditions significantly more than similar cities without such projects. These improvements included better basic water, sewerage and solid waste disposal. Factors in the relative success of these urban development projects have been involvement of both beneficiaries and borrowers, without straining their capacities or resources, and the use of lessons from prior experiences. The study also finds however, that despite the promising result, there is still much to learn about how many poor people are served by such projects and how many are not being served. The study calls for more systematic monitoring and evaluation of the poverty alleviation results of urban development assistance. This is a call echoed by practitioners who agree that knowing more about the results achieved thus far, can better inform assistance to the urban poor in the future.
Particle Swarm Optimization-Based Source Seeking

The task of locating a source based on the measurements of the signal emitted/emanating from it is called the source-seeking problem. In the past few years, there has been a lot of interest in deploying autonomous platforms for source-seeking. Some of the challenging issues with implementing autonomous source-seeking are the lack of a priori knowledge about the distribution of the emitted signal and presence of noise in both the environment and on-board sensor measurements. This paper proposes a planner for a swarm of robots engaged in seeking an electromagnetic source. The navigation strategy for the planner is based on Particle Swarm Optimization (PSO) which is a population-based stochastic optimization technique. An equivalence is established between particles generated in the traditional PSO technique, and the mobile agents in the swarm. Since the positions of the robots are updated using the PSO algorithm, modifications are required to implement the PSO algorithm on real robots to incorporate collision avoidance strategies. The modifications necessary to implement PSO on mobile robots, and strategies to adapt to real environments are presented in this paper. Our results are also validated on an experimental testbed.
One Money, One Market: A Revised Benchmark

The introduction of the euro generated substantial interest in the impact of currency unions (CUs) on trade flows. Initial estimates suggested a tripling of trade, which gave rise to a literature in search of “more reasonable” CU effects.Theoretical derivations of the gravity model highlight, however that the CU literature neglects to control simultaneously for general equilibrium effects (multilateral resistance) and unobserved bilateral heterogeneity among trade partners. Once we introduce the appropriate controls, CU trade effects are shown to range around 50%. We also highlight that the practice of reporting average CU effects generates misleading results. The average effect is shown to be a composite of disparate individual CU effects ranging from 40% (euro) to about 100% (Central African franc).
Origins of Life

This addresswas presented by Freeman J. Dyson as the NishinaMemorial Lecture at the University of Tokyo, on October 17, 1984, and at Yukawa Institute for Theoretical Physics, on October 23, 1984.
Earnings Manipulation and Expected Returns

An accounting-based earnings manipulation detection model has strong out-of-sample power to predict cross-sectional returns. Companies with a higher probability of manipulation (M-score) earn lower returns on every decile portfolio sorted by size, book-to-market, momentum, accruals, and short interest. The predictive power of M-score stems from its ability to forecast changes in accruals and is most pronounced among low-accrual (ostensibly “high-earnings-quality”) stocks. These findings support the investment value of careful fundamental and forensic analyses of public companies.
Undervaluation through foreign reserve accumulation : static losses, dynamic gains

This paper analyzes foreign reserve accumulation as a second-best policy in economies with learning-by-investing externalities that arise disproportionately from the tradable sector. Under closed capital accounts, reserve accumulation requires an increase in net exports, which reduces the domestic supply of tradable goods, raises their relative price in terms of non-tradable goods – i.e. undervalues the real exchange rate – and stimulates the production of tradable goods. The cost of such a policy is to reduce domestic tradable absorption. However, since the tradable sector generates learning-by-investing externalities, it leads to dynamic gains. Reserve accumulation always increases growth in our framework, but the net welfare effects depend on the balance between the static losses from lower tradable absorption and the dynamic gains from higher growth. We capture this trade-off in a simple analytic formula and depict it in an intuitive graph. We also discuss alternative policy options to reserve accumulation that serve to internalize learning-by-investing externalities.
What caused the long duration of the Paleocene-Eocene Thermal Maximum?

[1] Paleorecords show that the Paleocene-Eocene Thermal Maximum (PETM, � 56 Ma) was associated with a large carbon cycle anomaly and global warming >5 K, which persisted for at least 50 kyr. Conventional carbon cycle/climate models that include a single initial carbon input pulse over � 10 kyr fail to reproduce the long duration of the PETM without invoking additional, slow carbon release over more than 50 kyr (hereafter referred to as bleeding). However, a potential carbon source for the bleeding, as well as its release mechanism, has hitherto remained elusive. Here I present first-principle calculations of heat transfer in marine sediments which demonstrate that a bottom water temperature anomaly as generated during the PETM takes tens of thousands of years to penetrate the top few hundred meters of deep-sea sediments. While the initial temperature rise has been suggested to cause dissociation of the majority of oceanic methane hydrate within � 10 kyr, my calculations reveal a long tail of hydrate dissociation, causing smaller but continued carbon release substantially beyond 10 kyr. In addition, I suggest that temperature-enhanced metabolic processes in marine sediments and the absence of methane hydrate deposition during the PETM contributed to prolonged carbon input during the event. Enhanced fluxes of methane over this time scale would have sustained the carbon isotope excursion and amplified long-term greenhouse warming by elevating atmospheric concentrations of steady state CH4, or in oxidized form, CO2.
Robust Error Specification in a Production System

Economists estimating demand and supply systems face the question of using shares or quantities as dependent variables. This article finds that inconsistent estimates are obtained if one makes the wrong choice. A robust structure is presented to let the data choose the preferred form. Empirical applications to U.S. and Texas agriculture using the generalized method of moments suggest that shares and quantities are rejected in favor of a more general functional form. The Texas application provides some evidence for fixed capital but not for labor. Copyright 2013, Oxford University Press.
Bijections for refined restricted permutations

We present a bijection between 321- and 132-avoiding permutations that preserves the number of fixed points and the number of excedances. This gives a simple combinatorial proof of recent results of Robertson et al. (Ann. Combin. 6 (2003) 427), and Elizalde (Proc. FPSAC 2003). We also show that our bijection preserves additional statistics, which extends the previous results.
Interferon Regulatory Factor 4 Sustains CD8+ T Cell Expansion and Effector Differentiation

Summary Upon infection, CD8 + T cells undergo a stepwise process of early activation, expansion, and differentiation into effector cells. How these phases are transcriptionally regulated is incompletely defined. Here, we report that interferon regulatory factor 4 ( IRF4), dispensable for early CD8 + T cell activation, was vital for sustaining the expansion and effector differentiation of CD8 + T cells. Mechanistically, IRF4 promoted the expression and function of Blimp1 and T-bet, two transcription factors required for CD8 + T cell effector differentiation, and simultaneously repressed genes that mediate cell cycle arrest and apoptosis. Selective ablation of Irf4 in peripheral CD8 + T cells impaired antiviral CD8 + T cell responses, viral clearance, and CD8 + T cell-mediated host recovery from influenza infection. IRF4 expression was regulated by T cell receptor (TCR) signaling strength via mammalian target of rapamycin (mTOR). Our data reveal that IRF4 translates differential strength of TCR signaling into different quantitative and qualitative CD8 + T cell responses.
A reproducing kernel condition for indeterminacy in the multidimensional moment problem

Using the smallest eigenvalues of Hankel forms associated with a multidimensional moment problem, we establish a condition equivalent to the existence of a reproducing kernel. This result is a multivariate analogue of Berg, Chen, and Ismail's 2002 result. We also present a class of measures for which the existence of a reproducing kernel implies indeterminacy.
Muricatetrocins A and B and Gigantetrocin B: Three New Cytotoxic Monotetrahydrofuran-Ring Acetogenins from Annona muricata

Extracts from the seeds of Annona muricata yielded three new Annonaceous acetogenins: muricatetrocin A (= (5S)-3-{(2R)-2-hydroxy-9-{(2R,5S)-tetrahydro-5-[(1S,4S,5S)-1,4,5-trihydroxyheptadecyl]furan-2-yl}nonyl}-5-methylfuran-2(5H)-one; 1), muricatetrocin B (= (5S)-{(2R)-2-hydroxy-9-{(2S,5S)-tetrahydro-5-[(1S,4S,5S)-1,4,5-trihydroxyheptadecyl]furan-2-yl}nonyl}-5-methylfuran-2(5H)-one; 2), and gigantetrocin B (= (5S)-3-{(2R)-2-hydroxy-7-{(2S,5S)-tetrahydro-5-[(1S,4R,5R)-1,4,5-trihydroxynonadecyl]furan-2-yl}heptyl}-5-methyl-furan-2(5H)-one; 3). Their C-skeletons were deduced by mass spectrometry. Configurations were determined by 1H-NMR of ketal derivatives and 2D-NMR experiments utilizing Mosher esters. A previously described compound, gigantetrocin A (= (5S)-3-{(2R)-2-hydroxy-7-{(2S,5S)-tetrahydro-5-[(1S,4S,5S)-1,4,5-trihydroxynonadecyl]furan-2-yl}heptyl}-5-methylfuran-2-(5H)one; 4), was also isolated and is new to this species. Compounds 1–4 were all selectively cytotoxic for the HT-29 human colon-tumor cell line with potencies at least 10 times that of adriamycin.