cssi/SciSciGPT-SciSciNet huggingface dataset:
Flaw selection strategies for partial-order planning

Several recent studies have compared the relative efficiency of alternative flaw selection strategies for partial-order causal link (POCL) planning. We review this literature, and present new experimental results that generalize the earlier work and explain some of the discrepancies in it. In particular, we describe the Least-Cost Flaw Repair (LCFR) strategy developed and analyzed by Joslin and Pollack (1994), and compare it with other strategies, including Gerevini and Schubert's (1996) ZLIFO strategy. LCFR and ZLIFO make very different, and apparently conflicting claims about the most effective way to reduce search-space size in POCL planning. We resolve this conflict, arguing that much of the benefit that Gerevini and Schubert ascribe to the LIFO component of their ZLIFO strategy is better attributed to other causes. We show that for many problems, a strategy that combines least-cost flaw selection with the delay of separable threats will be effective in reducing search-space size, and will do so without excessive computational overhead. Although such a strategy thus provides a good default, we also show that certain domain characteristics may reduce its effectiveness.
Embedding Entities and Relations for Learning and Inference in Knowledge Bases

Abstract: We consider learning representations of entities and relations in KBs using the neural-embedding approach. We show that most existing models, including NTN (Socher et al., 2013) and TransE (Bordes et al., 2013b), can be generalized under a unified learning framework, where entities are low-dimensional vectors learned from a neural network and relations are bilinear and/or linear mapping functions. Under this framework, we compare a variety of embedding models on the link prediction task. We show that a simple bilinear formulation achieves new state-of-the-art results for the task (achieving a top-10 accuracy of 73.2% vs. 54.7% by TransE on Freebase). Furthermore, we introduce a novel approach that utilizes the learned relation embeddings to mine logical rules such as "BornInCity(a,b) and CityInCountry(b,c) => Nationality(a,c)". We find that embeddings learned from the bilinear objective are particularly good at capturing relational semantics and that the composition of relations is characterized by matrix multiplication. More interestingly, we demonstrate that our embedding-based rule extraction approach successfully outperforms a state-of-the-art confidence-based rule mining approach in mining Horn rules that involve compositional reasoning.
Forms of Semantic Specification

The way to specify a programming language has been a topic of heated debate for some decades and at present there is no consensus on how this is best done. Real languages are almost always specified informally; nevertheless, precision is often enough lacking that more formal approaches could benefit both programmers and language implementors. My purpose is to look at a few of these formal approaches in hope of establishing some distinctions or at least stirring some discussion. Comments University of Pennsylvania Department of Computer and Information Sciences Technical Report No. MSCIS-91-61. This technical report is available at ScholarlyCommons: http://repository.upenn.edu/cis_reports/337 Forms of Semantic Specification MS-CIS-91-61 Logic & Computation 37
A Novel Visual Word Co-occurrence Model for Person Re-identification

Person re-identification aims to maintain the identity of an individual in diverse locations through different non-overlapping camera views. The problem is fundamentally challenging due to appearance variations resulting from differing poses, illumination and configurations of camera views. To deal with these difficulties, we propose a novel visual word co-occurrence model. We first map each pixel of an image to a visual word using a codebook, which is learned in an unsupervised manner. The appearance transformation between camera views is encoded by a co-occurrence matrix of visual word joint distributions in probe and gallery images. Our appearance model naturally accounts for spatial similarities and variations caused by pose, illumination & configuration change across camera views. Linear SVMs are then trained as classifiers using these co-occurrence descriptors. On the VIPeR [1] and CUHK Campus [2] benchmark datasets, our method achieves 83.86% and 85.49% at rank-15 on the Cumulative Match Characteristic (CMC) curves, and beats the state-of-the-art results by 10.44% and 22.27%.
Competitive information systems in support of pricing

Recent highly publicized success stories have focused general managers' attention on so called "competitive information systems." But organizations attempting to identify systems that provide competitive advantage are finding the search to be frustrating and often unrewarding. This article combines two familiar information systems concepts, the Anthony framework and information attributes, to produce a methodology for identifying one class of competitive information systems, systems in support of product pricing. A number of examples demonstrate the descriptive utility of the classification scheme, and provide a synergistic vehicle for the discovery of new applications.
OBJECT-ORIENTED QUERIES: EQUIVALENCE AND OPTIMIZATION*

We are interested in efficiently accessing data in an object-oriented database. We have developed a query algebra which fully supports object identity and abstract data types, and have identified a variety of algebraic query transformations. The equivalence of two queries is complicated by the presence of object identity. In this paper we define a hierarchy of notions of equivalence for queries, and present examples of equivalent query transformations for each level of the hierarchy.
Breakdown of the area theorem: carrier-wave Rabi flopping of femtosecond optical pulses

Summary form only. The development of high-intensity ultrashort optical pulses has lead to a number of fascinating nonlinear optical propagation studies including Rabi flopping, self-induced transparency, and photon echo, to name but a few. Common to the description of these effects, is that their propagation phenomena can be described quite adequately by employing the appropriate coupled matter-Maxwell equations within the slowly-varying-envelope approximation (SVEA), i.e., the envelopes of the electromagnetic field and polarization are assumed to vary little over an optical period and wavelength. However, for several-cycle optical pulses this approximation becomes seriously questionable.
Fatigue Provisions of AASHTO Specifications

The statistical properties of fatigue strength of various types of weldments are analyzed from which the allowable fatigue stresses are computed. Results compare favorably with those of the AASHTO Fatigue Specifications (1973). The North Carolina 1972 vehicular traffic data are used to derive the statistical properties of vehicle type, weight, and traffic intensity. The information of fatigue strength and vehicular traffic are used to compute the probabilities of fatigue failure of weldments of two bridges, one narrow and the other of the wider variety, both designed according to the AASHTO Specifications (1973). Results show that the probability of failure values of the weldments of these two bridges differ drastically, the difference being attributable to the lateral load distribution factor recommended by the specifications. The manner in which the lateral load distribution factor may be revised so as to yield structures with desired but uniform reliability against fatigue failure is given.
Heat Flux Measurement

This chapter reviews the most useful current heat flux instrumentation, particularly heat flux gauges. It also briefly discusses the optical methods, but these are generally research methods that require sophisticated equipment and data processing techniques. General principles for the proper use of heat flux gauges are discussed first, followed by the details of specific gauges along with some of their typical applications. Three classifications of gauges are considered based on measured temperature difference over space, the temperature change with time, and the power dissipated at a maintained temperature. The measurement methods are also categorized according to the type of temperature measurement. The three common techniques are thermocouples, resistance temperature devices (RTDs), and optical. Finally, the chapter discusses the calibration of heat flux gauges along with error analysis. There are a number of problems and complications that should be taken into account while planning for any heat flux measurements. Keywords: calibration; error analysis; heat flux gauges; heat flux measurement; optical methods; resistance temperature devices (RTDs); thermocouples
Economy-wide implications of direct and indirect policy interventions in the water sector: lessons from recent work and future research needs

Water is increasingly becoming a limiting factor for sustainable economic growth and development in many countries. Its allocation has significant impacts on overall economic efficiency, particularly with growing physical scarcity in certain regions. Greater water supply variability further increases vulnerability in affected regions. Water also has become a strategic resource involving conflicts among those who may be affected differently by various policies. This paper analyzes various policy interventions aimed at improving water allocation decisions, using a novel approach that incorporates macro and micro level considerations in a unified analytical framework. The framework facilitates assessment of various linkages among policies and their impacts within individual sectors and economy-wide. Drawing on country based studies in Morocco, South Africa, Turkey, and Mexico, the analysis reveals difficult tradeoffs among various policy objectives, including priorities placed on different sectors, regional advantages, and general economic efficiency gains versus broader social impacts. The comparison of policy impacts demonstrates the usefulness of the framework in information that policy makers can use to rank the policy interventions according to the emphasis placed on different policy objectives. The paper also compares approaches used in other studies that apply computable general equilibrium models in various contexts of water, environment and agriculture.
Distinguishing between types of data and methods of collecting them

In the quantitative-qualitative debate, analysts often fail to make a clear distinction between methods of data collection used and types of data generated. Using characteristic information needs for health planning derived from data on the use of health services, this paper shows that each combination of method (contextual or noncontextual) and data (quantitative or qualitative) is a unique primary source of information. Hentschel examines the role of different data collection methods-including the types of data they produce - in the analysis of social phenomena in developing countries. He points out that one confusing factor in the quantitative-qualitative debate is that a distinction is not clearly made between methods of data collection used and types of data generated. He maintains the divide between quantitative and qualitative types of data but analyzes methods according to their contextuality: the degree to which they try to understand human behavior in the social, cultural, economic, and political environment of a given place. He emphasizes that it is most fruitful to think of both methods and data as lying on a continuum stretching from more to less contextual methodology and from more to less qualitative data output. Using characteristic information needs for health planning derived from data on the use of health services, he shows that each combination of method (more or less contextual) and data (more or less qualitative) is a unique primary source that can fulfill different information requirements. He concludes that: ° Certain information about health utilization can be obtained only through contextual methods - in which case strict statistical representability must give way to inductive conclusions, assessments of internal validity, and replicability of results. ° Often contextual methods are needed to design appropriate noncontextual data collection tools. ° Even where noncontextual data collection methods are needed, contextual methods can play an important role in assessing the validity of the results at the local level. ° In cases where different data collection methods can be used to probe general results, the methods can - and need to be - formally linked. This paper - a product of the Poverty Group, Poverty Reducation and Economic Management Network - is part of a larger effort in the network to combine research methods from different disciplines in the design of poverty reduction strategies. The author may be contacted at jhentschel@worldbank.org.
CHANGES IN CHINA'S URBAN FOOD CONSUMPTION AND IMPLICATIONS FOR TRADE

Detailed data from 3,500 urban Chinese households are used to estimate demand elasticities and the impacts of regional and demographic variables for 17 food products through a two-stage budgeting procedure with complete demand systems. Results suggest that China's food consumption patterns will continue to shift from grains to high value food products and the ongoing transition in food consumption will affect China's domestic food markets and trade behavior.
Photoinduced electron transfer in organic systems: control of back electron transfer

Article de synthese d'etudes experimentales recentes consacrees a diverses methodes d'inhibition du retrotransfert d'electrons en photochimie organique
Numerical Semigroups on Compound Sequences

We generalize the geometric sequence {ap, ap−1b, ap−2b2,…, bp} to allow the p copies of a (resp. b) to all be different. We call the sequence {a1a2a3… ap, b1a2a3…ap, b1b2a3…ap,…, b1b2b3…bp} a compound sequence. We consider numerical semigroups whose minimal set of generators form a compound sequence, and compute various semigroup and arithmetical invariants, including the Frobenius number, Apery sets, Betti elements, and catenary degree. We compute bounds on the delta set and the tame degree.
Current distribution in paralleled thyristors - a comparative analysis of 5 real cases in high current transformer - rectifiers

It is very well known that in high current transformer-rectifiers it is necessary to connect several thyristors in parallel for each secondary phase. Current distribution between thyristors in parallel strongly depends on the symmetry of the mechanical structure of rectifier. The current in one thyristor not always is given by total current of secondary phase divided by the number of thyristors in parallel, as it is in ideal cases. In this paper a comparative analysis of 5 different real cases of current distribution is presented. This real cases correspond to 6 pulses controlled rectifiers measured indifferent copper plants. Finally conclusions and design recommendations are given.
Improving Space Object Catalog Maintenance Through Advances in Solar Radiation Pressure Modeling

This paper investigates the weaknesses of using the cannonball model to represent the solar radiation pressure force on an object in an orbit determination process, and it presents a number of alternative models that greatly improve the orbit determination performance. These weaknesses are rooted in the fact that the cannonball model is not a good representation of the true solar radiation pressure force acting on an arbitrary object. Using an erroneous force model results in poor estimates, inaccurate trajectory propagation, unrealistic covariances, and the inability to fit long and/or dense arcs of data. The alternative models presented are derived from a Fourier series representation of the solar radiation pressure force. The simplest instantiation of this model requires only two more parameters to be estimated, however, this results in orders of magnitude improvements in tracking accuracy. This improvement is illustrated through numerical examples of a discarded upper stage in a geosynchronous transfe...
One-dimensional k-center on uncertain data

Problems on uncertain data have attracted significant attention due to the imprecise nature of many measurement data. In this paper, we consider the k-center problem on one-dimensional uncertain data. The input is a set P of (weighted) uncertain points on a real line, and each uncertain point is specified by its probability density function (pdf) which is a piecewise-uniform function (i.e., a histogram). The goal is to find a set Q of k points on the line to minimize the maximum expected distance from the uncertain points of P to their expected closest points in Q. We present efficient algorithms for this uncertain k-center problem and their running times almost match those for the "deterministic" k-center problem.
Conductance reduction without shot noise in quantum wires

We show that a shot noise free current at conductance below 2 e^2/h is possible in short interacting quantum wires without spin-polarization. Our calculation is done for two exactly solvable limits of the ``Coulomb Tonks gas'', a one-dimensional gas of impenetrable electrons that can be realized in ultra-thin quantum wires. In both cases we find that charge transport through such a wire is noiseless at zero temperature while the conductance is reduced to e^2/h.
New Techniques in Neutron Data Measurements Above 30 MeV

Recent developments in experimental facilities have enabled new techniques for measurements of neutron interactions above 30 MeV. Foremost is the development of both monoenergetic and continuous neutron sources using accelerators in the medium energy region between 100 and 800 MeV. Measurements of the reaction products have been advanced by the continuous improvement in detector systems, electronics and computers. Corresponding developments in particle transport codes and in the theory of nuclear reactions at these energies have allowed more precise design of neutron sources, experimental shielding and detector response. As a result of these improvements, many new measurements are possible and the data base in this energy range is expanding quickly.
Jupiter's occultation radii: Implications for its internal dynamics

[1] The physical shape of a giant planet can reveal important information about its centrifugal potential, and therefore, its rotation. In this paper we investigate the response of Jupiter's shape to differential rotation on cylinders of various cylindrical radii using a simple equipotential theory. We find that both solid-body rotation (with System III rotation rate) and differential rotation on cylinders up to a latitude between 20 and 30 degrees are consistent with Jupiter's measured shape. Occultation measurements of Jupiter's shape could provide an independent method to constrain the depth of its zonal winds.
Uncomputability and Physical Law

This paper investigates the role that uncomputability plays in the laws of physics. While uncomputability might seem like an abstract mathematical concept, many questions in physics involve uncomputability. In particular, the form of the energy spectrum of quantum systems capable of universal computation is uncomputable: to answer whether a Hamiltonian system is gapped or gapless in a particular sector requires one to solve the Halting problem. Finally, the problem of determining the most concise expression of physical laws requires one to determine the algorithmic complexity of those laws, and so, the answer to this problem is uncomputable.
An N =2 Supersymmetric Membrane Flow

Abstract We find M-theory solutions that are holographic duals of flows of the maximally supersymmetric ( N =8 ) scalar-fermion theory in 2+1 dimensions. In particular, we construct the M-theory solution dual to a flow in which a single chiral multiplet is given a mass, and the theory goes to a new infra-red fixed point. We also examine this new solution using M2-brane probes. The (2+1)-dimensional field theory fixed-point is closely related to that of Leigh and Strassler, while the M-theory solution is closely related to the corresponding IIB flow solution. We recast the IIB flow solution in a more geometric manner and use this to obtain an ansatz for the M-theory flow. We are able to generalize our solution further to obtain flows with del Pezzo submanifolds, and we give an explicit solution with a conifold singularity.
Interior-point algorithms for linear-programming decoding

Interior-point algorithms constitute a very interesting class of algorithms for solving linear-programming problems. In this paper we study efficient implementations of such algorithms for solving the linear program that appears in the linear-programming decoder formulation.
A back-to-basics empirical study of priority queues

The theory community has proposed several new heap variants in the recent past which have remained largely untested experimentally. We take the field back to the drawing board, with straightforward implementations of both classic and novel structures using only standard, well-known optimizations. We study the behavior of each structure on a variety of inputs, including artificial workloads, workloads generated by running algorithms on real map data, and workloads from a discrete event simulator used in recent systems networking research. We provide observations about which characteristics are most correlated to performance. For example, we find that the L1 cache miss rate appears to be strongly correlated with wallclock time. We also provide observations about how the input sequence affects the relative performance of the different heap variants. For example, we show (both theoretically and in practice) that certain random insertion-deletion sequences are degenerate and can lead to misleading results. Overall, our findings suggest that while the conventional wisdom holds in some cases, it is sorely mistaken in others.
False-name-proofness with bid withdrawal

We study a more powerful variant of false-name manipulation in Internet auctions: an agent can submit multiple false-name bids, but then, once the allocation and payments have been decided, withdraw some of her false-name identities (have some of her false-name identities refuse to pay). While these withdrawn identities will not obtain the items they won, their initial presence may have been beneficia to the agent's other identities. We defin a mechanism to be false-name-proof with withdrawal (FNPW) if the aforementioned manipulation is never beneficial FNPW is a stronger condition than false-name-proofness (FNP).We discuss the relation between FNP and FNPW in general combinatorial auction settings. We also propose the maximum marginal value item pricing (MMVIP) mechanism, which we prove is FNPW. (The full version contains a number of other results.)
Lorentz-Violating Supergravity

The standard forms of supersymmetry and supergravity are inextricably wedded to Lorentz invariance. Here a Lorentz-violating form of supergravity is proposed. The superpartners have exotic properties that are not possible in a theory with exact Lorentz symmetry and micro causality. For example, the bosonic sfermions have spin 1/2 and the fermionic gauginos have spin 1. The theory is based on a phenomenological action that is shown to follow from a simple microscopic and statistical picture.
Molecular Gas in Spiral Galaxies

In this review, I highlight a number of recent surveys of molecular gas in nearby spiral galaxies. Through such surveys, more complete observations of the distribution and kinematics of molecular gas have become available for galaxies with a wider range of properties (e.g., brightness, Hubble type, strength of spiral or bar structure). These studies show the promise of both interferometers and single-dish telescopes in advancing our general understanding of molecular gas in spiral galaxies. In particular, I highlight the contributions of the recent BIMA Survey of Nearby Galaxies (SONG).
Local systems on nilpotent orbits and weighted Dynkin diagrams

We study the Lusztig-Vogan bijection for the case of a local system. We compute the bijection explicitly in type A for a local system and then show that the dominant weights obtained for different local systems on the same orbit are related in a manner made precise in the paper. We also give a conjecture (putatively valid for all groups) detailing how the weighted Dynkin diagram for a nilpotent orbit in the dual Lie algebra should arise under the bijection.
Muon colliders: New prospects for precision physics and the high energy frontier

An overview is given of muon collider technology and of the current status of the muon collider research program. The exciting potential of muon colliders for both neutrino physics and collider physics studies is then described and illustrated using self-consistent collider parameter sets at 0.1 TeV to 100 TeV center-of-mass energies.
Comprehensive and reliable crowd assessment algorithms

Evaluating workers is a critical aspect of any crowdsourcing system. In this paper, we devise techniques for evaluating workers by finding confidence intervals on their error rates. Unlike prior work, we focus on “conciseness”—that is, giving as tight a confidence interval as possible. Conciseness is of utmost importance because it allows us to be sure that we have the best guarantee possible on worker error rate. Also unlike prior work, we provide techniques that work under very general scenarios, such as when not all workers have attempted every task (a fairly common scenario in practice), when tasks have non-boolean responses, and when workers have different biases for positive and negative tasks. We demonstrate conciseness as well as accuracy of our confidence intervals by testing them on a variety of conditions and multiple real-world datasets.
Dynamic Model for RNA-seq Data Analysis

By measuring messenger RNA levels for all genes in a sample, RNA-seq provides an attractive option to characterize the global changes in transcription. RNA-seq is becoming the widely used platform for gene expression profiling. However, real transcription signals in the RNA-seq data are confounded with measurement and sequencing errors and other random biological/technical variation. To extract biologically useful transcription process from the RNA-seq data, we propose to use the second ODE for modeling the RNA-seq data. We use differential principal analysis to develop statistical methods for estimation of location-varying coefficients of the ODE. We validate the accuracy of the ODE model to fit the RNA-seq data by prediction analysis and 5-fold cross validation. To further evaluate the performance of the ODE model for RNA-seq data analysis, we used the location-varying coefficients of the second ODE as features to classify the normal and tumor cells. We demonstrate that even using the ODE model for single gene we can achieve high classification accuracy. We also conduct response analysis to investigate how the transcription process responds to the perturbation of the external signals and identify dozens of genes that are related to cancer.
Large-Amplitude Long-Wave Instability of a Supersonic Shear Layer

For sufficiently high Mach numbers, small disturbances on a supersonic vortex sheet are known to grow in amplitude because of slow nonlinear wave steepening. Under the same external conditions, linear theory predicts slow growth of long-wave disturbances to a thin supersonic shear layer. An asymptotic formulation is given here which adds nonzero shear-layer thickness to the weakly nonlinear formulation for a vortex sheet. Spatial evolution is considered, for a spatially periodic disturbance having amplitude of the same order, in Reynolds number, as the shear-layer thickness. A quasi-equilibrium inviscid nonlinear critical layer is found, with effects of diffusion and slow growth appearing through nonsecularity condition. Other limiting cases are also considered, in an attempt to determine a relationship between the vortex-sheet limit and the long-wave limit for a thin shear layer; there appear to be three special limits, corresponding to disturbances of different amplitudes at different locations along the shear layer.
Galaxy evolution in groups and clusters: star formation rates, red sequence fractions and the persistent bimodality

Author(s): Wetzel, AR; Tinker, JL; Conroy, C | Abstract: Using galaxy group/cluster catalogues created from the Sloan Digital Sky Survey Data Release 7, we examine in detail the specific star formation rate (SSFR) distribution of satellite galaxies and its dependence on stellar mass, host halo mass and halo-centric radius. All galaxies, regardless of central satellite designation, exhibit a similar bimodal SSFR distribution, with a strong break at SSFR ≈ 10 -11yr -1 and the same high SSFR peak; in no regime is there ever an excess of galaxies in the 'green valley'. Satellite galaxies are simply more likely to lie on the quenched ('red sequence') side of the SSFR distribution. Furthermore, the satellite quenched fraction excess above the field galaxy value is nearly independent of galaxy stellar mass. An enhanced quenched fraction for satellites persists in groups with halo masses down to 3 × 10 11M ⊙ and increases strongly with halo mass and towards halo centre. We find no detectable quenching enhancement for galaxies beyond ∼2R vir around massive clusters once these galaxies have been decomposed into centrals and satellites. These trends imply that (1) galaxies experience no significant environmental effects until they cross within ∼R vir of a more massive host halo; (2) after this, star formation in active satellites continues to evolve in the same manner as active central galaxies for several Gyr; and (3) once begun, satellite star formation quenching occurs rapidly. These results place strong constraints on satellite-specific quenching mechanisms, as we will discuss further in companion papers. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.
Admissibility of Fixpoint Induction over Partial Types

Partial types allow the reasoning about partial functions in type theory. The partial functions of main interest are recursively computed functions, which are commonly assigned types using fixpoint induction. However, fixpoint induction is valid only on admissible types. Previous work has shown many types to be admissible, but has not shown any dependent products to be admissible. Disallowing recursion on dependent product types substantially reduces the expressiveness of the logic; for example, it prevents much reasoning about modules, objects and algebras. In this paper I present two new tools, predicate-admissibility and monotonicity, for showing types to be admissible. These tools show a wide class of types to be admissible; in particular, they show many dependent products to be admissible. This alleviates difficulties in applying partial types to theorem proving in practice. I also present a general least upper bound theorem for fixed points with regard to a computational approximation relation, and show an elegant application of the theorem to compactness.
A simple insight into iterative belief propagation's success

In non-ergodic belief networks the posterior belief of many queries given evidence may become zero. The paper shows that when belief propagation is applied iteratively over arbitrary networks (the so called, iterative or loopy belief propagation (IBP)) it is identical to an arc-consistency algorithm relative to zero-belief queries (namely assessing zero posterior probabilities). This implies that zero-belief conclusions derived by belief propagation converge and are sound. More importantly, it suggests that the inference power of IBP is as strong and as weak as that of arcconsistency. This allows the synthesis of belief networks for which belief propagation is useless on one hand, and focuses the investigation on classes of belief networks for which belief propagation may be zero-complete. Finally, we show empirically that IBP's accuracy is correlated with extreme probabilities, therefore explaining its success over coding applications.
Palladium-catalyzed cyclization of alkenyl β-keto esters in the presence of chlorotrimethylsilane

PdCl2(CH3CN)2 catalyzed the cyclization of alkenyl β-keto esters in the presence of a stoichiometric amount of SiMe3Cl to form 2-carboalkoxycyclohexanones in good yield with excellent regioselectivity.
The perilous leap between exploration and exploitation

Research summary: R&D-based exploration and exploitation are necessary in order for firms to have sustainable competitive advantage. Yet, transitioning between these orthogonal types of R&D is considered profound organizational change. Building on recent research showing that compact, significant changes in R&D expenditure is an antecedent to the transition between explorative and exploitative R&D, I show that this leap between exploration and exploitation is quite hazardous. The magnitude of changes in R&D expenditure, whether increases or decreases, is positively associated with organizational failure. Firms maintaining higher levels of absorptive capacity are more capable of surviving the leap from R&D-based exploitation to exploration, and firms that do not use reductions in R&D expenditure to manipulate short-term earnings performance are more likely to survive the leap from exploration to exploitation. Managerial summary: In order to survive and thrive, innovative companies must be able to exploit their existing competencies, and to explore for new ones once those current competencies decline in value. However, transiting from one form of innovation to the other is difficult because the skills required to explore are fundamentally opposed to those required to exploit. In this article, I describe how difficult this leap between exploration and exploitation can be. I show that the move between R&D-based exploration and exploitation is related to organizational failure. In addition, firms that are superior learners are more likely to survive the leap from exploitation to exploration, and firms that are not cutting R&D expenditure to manipulate earnings are more likely to survive the leap from exploration to exploitation. Copyright © 2015 John Wiley & Sons, Ltd.
Export entrepreneurs : evidence from Peru

This paper examines firm entry and survival in exporting, and in products and markets not previously served by any domestic exporters. The authors use data on the nontraditional agriculture sector in Peru, which grew seven-fold from 1994 to 2007. They find tremendous firm entry and exit in the export sector, with exits more likely after one year and among firms that start small. There is also significant entry and exit in new markets. In contrast, such trial and error in new products is rare. New products are typically discovered by large experienced exporters and there is increased entry after products are discovered. The results imply that high sunk costs of entry are of concern for product discovery, especially for products that are not consumed domestically. In contrast, the tremendous entry and exit in exporting and in new markets suggests that initial sunk costs are relatively low. The authors develop a model that explains how entrepreneurs decide to export and to develop new export products and markets when there are sunk costs of discovery and uncertainty about idiosyncratic costs. The model explains many features of the data.
Flowing to Higher Dimensions: A New Strongly-Coupled Phase on M2 Branes

We describe a one-parameter family of new holographic RG flows that start from AdS 4 × S 7 and go to $$ \widehat{Ad{S}_5}\times \mathrm{\mathcal{B}}6 $$ , where $$ \mathrm{\mathcal{B}}6 $$ is conformal to a Kahler manifold and $$ \widehat{Ad{S}_5} $$ is Poincare AdS 5 with one spatial direction compactified and fibered over $$ \mathrm{\mathcal{B}}6 $$ . The new solutions “flow up dimensions,” going from the (2 + 1)-dimensional conformal field theory on M2 branes in the UV to a (3 + 1)-dimensional field theory on intersecting M5 branes in the infra-red. The M2 branes completely polarize into M5 branes along the flow and the Poincare sections of the $$ \widehat{Ad{S}_5} $$ are the (3 + 1)-dimensional common intersection of the M5 branes. The emergence of the extra dimension in the infra-red suggests a new strongly-coupled phase of the M2 brane and ABJM theories in which charged solitons are becoming massless. The flow solution is first analyzed by finding a four-dimensional $$ \mathcal{N}=2 $$ supersymmetric flow in $$ \mathcal{N}=8 $$ gauged supergravity. This is then generalized to a one parameter family of non-supersymmetric flows. The infra-red limit of the solutions appears to be quite singular in four dimensions but the uplift to eleven-dimensional supergravity is remarkable and regular (up to orbifolding). Our construction is a non-trivial application of the recently derived uplift formulae for fluxes, going well beyond the earlier constructions of stationary points solutions. The eleven-dimensional supersymmetry is also analyzed and shows how, for the supersymmetric flow, the M2-brane supersymmetry in the UV is polarized entirely into M5-brane supersymmetry in the infra-red.
The Effect Of Boundary Conditions On Efficiency And Pricing In Double-Auction Markets With Zero-Intelligence Agents

The computational tractability of many markets with computerized agents requires they be subject to boundary conditions that are both unnecessary and undesirable in markets with humans. In particular, double-auction markets with zero-intelligence agents, which are a standard baseline in computational economics, constrain all bids, offers and trade prices to lie between an upper and a lower bound. This paper shows how changes in these boundary conditions influence pricing and efficiency. It is found that boundary conditions consistent with competitive pricing are generally inconsistent with the most efficient operation of those markets. Copyright © 2012 John Wiley & Sons, Ltd.
Development of control models for the planning of sustainable transportation systems

Planning of sustainable transportation systems requires integration of multiple systems while considering a holistic approach. A limited amount of research has been conducted that simultaneously considers all the transportation, economic activity, environmental and social effects. The proposed research envisages incorporating considerations related to sustainability and providing solutions to stakeholders in policy making. In this paper, a dynamic model for planning and development of sustainable transportation systems is presented. This is given by a system of three nonlinear differential equations representing the dynamics of the three independent states, namely, transportation, activity, and environmental systems. A policy scenario considering investment in energy efficient technologies and its effects on the states is discussed to assist making investment decisions. Optimal control techniques are used to design the controls. The results show that it is possible to formulate an optimal control to achieve the desired target. Numerical results, based on actual parameters, are presented to illustrate the long-term trends of the states. The methodology discussed in this paper will be helpful to decision makers in making optimal decisions. The contribution of this research work is the introduction of a systems and controls methodology to develop optimal policies for the design of sustainable systems.
On the Mechanism of Ultra Thin Silicon Oxide Film Growth During Thermal Oxidation

The growth of ultra-thin oxide films by the thermal oxidation of silicon has been studied by low and medium energy ion scattering spectroscopies (LEIS and MEIS) and X-ray photoelectron spectroscopy (XPS). To help elucidate the diffusional and mechanistic aspects of oxide growth we have used sequential isotope oxidation (18O2 followed by 16O2). LEIS demonstrates that both 18O and 16O atoms are on the silicon surface under our growth conditions. MEIS also distinguishes 18O from 16O and gives a depth distribution for both with high accuracy. Our results show that several key aspects of the Deal-Grove model (oxygen diffusion to the Si-SiO2 interface and oxide formation at the interface) are consistent with our results for 50A films. For very thin oxide films (15A or less), we found a mixed isotopic distribution in the film, demonstrating more complex oxidation behavior.
Advanced Heat Transfer and Thermal Storage Fluids

The design of the next generation solar parabolic trough systems for power production will require the development of new thermal energy storage options with improved economics or operational characteristics. Current heat transfer fluids such as VP-1™ which consist of a eutectic mixture of biphenyl and diphenyl oxide, allow a maximum operating temperature of ca. 300°C for a direct thermal storage system, At higher temperatures the vapor pressure would become too high and would require pressure rated tanks. The use of VP-1™ also suffers from a freezing point around 13°C that requires heating during cold periods. One of the goals for future trough systems is the use of heat transfer fluids that can act as thermal storage media and that are stable to around 425°C and have a freezing point near or below 0°C. This paper presents an outline of our latest approach towards the development of such thermal storage fluids.Copyright © 2005 by ASME
Sub-quarter micron silicon integrated circuits and single wafer processing

This paper describes the role of single wafer processing in the development of sub-quarter micron silicon integrated circuits (ICs). The issues related to device processing, choice of materials, performance, reliability, and manufacturing are covered. Single wafer processing based rapid photothermal processing (dominant photons with wavelength less than about 800 nm) is an ideal answer to almost all the thermal processing requirements of current and future Si ICs. For process integration, a new model for process optimization based on minimization of thermal stress is proposed. For breaking the sub-100 nm manufacturing barriers, high throughput lithography based on direct writing is a proposed solution.
A novel phase transition in alloys

Abstract The intermediate phase of the intermetallic alloy CsPb is shown to be a plastic crystal characterized by jump reorientations of Cs 4 Pb 4 structural units. The wavevector variation of the elastic and quasielastic neutron scattering intensities is well reproduced by a simple model of independent structural units jumping between the four orientations observed in the crystal at room temperature. This represents the first observation of a plastic crystal phase in a metal alloy.
Theory of myelin coiling

A new model is proposed to explain coiling of myelins composed of fluid bilayers. This model allows the constituent bilayer cylinders of a myelin to be non-coaxial and the bilayer lateral tension to vary from bilayer to bilayer. The calculations show that a myelin would bend or coil to lower its free energy when the bilayer lateral tension is sufficiently large. From a mechanical point of view, the proposed coiling mechanism is analogous to the classical Euler buckling of a thin elastic rod under axial compression. The analysis of a simple two-bilayer case suggests that a bilayer lateral tension of about 1 dyne/cm can easily induce coiling of myelins of typical lipid bilayers. This model signifies the importance of bilayer lateral tension in determining the morphology of myelinic structures.
Marginal-Stability Calculation of Electron Temperature Profiles in Tokamaks

Electron temperature profiles, turbulence levels, and anomalous transport are calculated for tokamak discharges using the hypothesis that the dissipative trapped-electron instability drives the plasma to marginal stability. (AIP)
Taubes’s proof of the Weinstein conjecture in dimension three

Does every smooth vector field on a closed three-manifold, for example the three-sphere, have a closed orbit? No, according to counterexamples by K. Kuperberg and others. On the other hand there is a special class of vector fields, called Reeb vector fields, which are associated to contact forms. The three-dimensional case of the Weinstein conjecture asserts that every Reeb vector field on a closed oriented three-manifold has a closed orbit. This conjecture was recently proved by Taubes using Seiberg-Witten theory. We give an introduction to the Weinstein conjecture, the main ideas in Taubes’s proof, and the bigger picture into which it fits. Taubes’s proof of the Weinstein conjecture is the culmination of a large body of work, both by Taubes and by others. In an attempt to make this story accessible to nonspecialists, much of the present article is devoted to background and context, and Taubes’s proof itself is only partially explained. Hopefully this article will help prepare the reader to learn the full story from Taubes’s paper [62]. More exposition of this subject (which was invaluable in the preparation of this article) can be found in the online video archive from the June 2008 MSRI hot topics workshop [44], and in the article by Auroux [5]. Below, in §1–§3 we introduce the statement of the Weinstein conjecture and discuss some examples. In §4–§6 we discuss a natural strategy for approaching the Weinstein conjecture, which proves it in many but not all cases, and provides background for Taubes’s work. In §7 we give an overview of the big picture surrounding Taubes’s proof of the Weinstein conjecture. Readers who already have some familiarity with the Weinstein conjecture may wish to start here. In §8–§9 we recall necessary material from Seiberg-Witten theory. In §10 we give an outline of Taubes’s proof, and in §11 we explain some more details of it. To conclude, in §12 we discuss some further results and open problems related to the Weinstein conjecture. 1. Statement of the Weinstein conjecture The Weinstein conjecture asserts that certain vector fields must have closed orbits. Before stating the conjecture at the end of this section, we first outline its origins. This is discussion is only semi-historical, because only a sample of the relevant works will be cited, and not always in chronological order. 1.1. Closed orbits of vector fields. Let Y be a closed manifold (in this article all manifolds and all objects defined on them are smooth unless otherwise stated), 2000 Mathematics Subject Classification. 57R17,57R57,53D40. Partially supported by NSF grant DMS-0806037.
The Problem of the Origin of Species as it Appeared to Darwin in 1859 and as it Appears to us To-day

The Problem of the Origin of Species as it Appeared to Darwin in 1859 and as it Appears to us To-day 1
Skull base surgery for malignancy: when not to operate

The purpose of this paper is to detail the contraindications for surgery, with curative intent for those patients who suffer from a head and neck malignancy that invades the intracranial space. This is based on a 30-year experience of over 250 patients. The most important contraindications are anatomical. Surgery is not done if the following structures are invaded: brain stem, eloquent portions of the cerebrum, superior sagittal sinus, both internal carotid arteries, both cavernous sinuses and certain vital bridging veins. Certain tumor factors are absolute but are occasionally relative contraindications: such as distant metastatic disease especially if multiple and at multiple anatomic sites. Some tumors that behave in a particularly virulent fashion that defy complete resection but are often difficult to predict preoperatively. Lack of patient medical fitness or absence of patient commitment to the operative procedure is make-up two serious contraindications to surgery.