cssi/SciSciGPT-SciSciNet huggingface dataset:
A sound and complete algorithm for learning causal models from relational data

The PC algorithm learns maximally oriented causal Bayesian networks. However, there is no equivalent complete algorithm for learning the structure of relational models, a more expressive generalization of Bayesian networks. Recent developments in the theory and representation of relational models support lifted reasoning about conditional independence. This enables a powerful constraint for orienting bivariate dependencies and forms the basis of a new algorithm for learning structure. We present the relational causal discovery (RCD) algorithm that learns causal relational models. We prove that RCD is sound and complete, and we present empirical results that demonstrate effectiveness.
Continuous selections of the inverse numerical range map

For a complex -by- matrix , the numerical range is the range of the map acting on the unit sphere in . We ask whether the multivalued inverse numerical range map has a continuous single-valued selection defined on all or part of . We show that for a large class of matrices, does have a continuous selection on . For other matrices, has a continuous selection defined everywhere on except in the vicinity of a finite number of exceptional points on the boundary of .
Communication complexity of remote state preparation with entanglement

We consider the problem of remote state preparation recently studied in several papers. We study the communication complexity of this problem, in the presence of entanglement and in the scenario of single use of the channel.
A Biological Coevolution Model with Correlated Individual-Based Dynamics

The dynamics of biological coevolution poses many problems of interest to the statistical-physics and complexsystems communities [1, 2]. Recently, we studied a coevolution model that is a simplified version of the one introduced by Hall, et al. [3, 4, 5, 6]. Our model, in which individuals give birth, mutate and die, displays punctuated equilibrialike, quiet periods interrupted by bursts of mass extinctions [7, 8]. Interactions in this model were given by a random interaction matrix. Here we report on a modified version of the model, in which we have added correlations to the interaction matrix in order to increase the biological realism. The modified model is compared with the original one to assess the effects of correlations.
The effects of skull thickness variations on human head dynamic impact responses

Variations in human skull thickness affecting human head dynamic impact responses were studied by finite element modeling techniques, experimental measurements, and histology examinations. The aims of the study were to better understand the influences of skull thickness variations on human head dynamic impact responses and the injury mechanisms of human head during direct impact. The thicknesses of the frontal bone of seven human cadaver skulls were measured using ultrasonic technology. These measurements were compared with previous experimental data. Histology of the skull was recorded and examined. The measured data were analyzed and then served as a reference to vary the skull thickness of a previously published three-dimensional finite element human head model to create four models with different skull thickness. The skull thicknesses modeled are 4.6 mm, 5.98 mm, 7.68 mm, and 9.61 mm. These models were impacted by a cylinder with a mass of 5.23 kg and an initial velocity of 6.33 m/s. Model responses were compared between models in terms of intracranial pressures, head impact accelerations, brain shear stresses, and skull von Mises stresses. It has been shown that the thickness of the skull influenced the dynamic responses of the head during direct impact. As skull thickness increased, skull deformation decreased as the skull absorbed less impact energy. However, this relationship cannot be linearly interpolated to the other parameters such as head acceleration and intracranial pressure responses. Based on model responses to half-sine wave pulses, skull and brain iso-stress curves were constructed for the thicker and thinner skulls. Thresholds for skull fracture and reversible concussion were established for the population represented by these skulls.
REGIONAL PLANNING STRATEGIES FOR HYBRID ENERGY OPTIMIZATION

Publisher Summary This chapter reviews the regional planning strategies for hybrid energy optimization. Some of the available fuels and energy sources include coal, crops grown for energy, fertile nuclear, fission nuclear, geothermal, hydraulic systems including hydroelectric, natural gas, ocean thermal, oil, oil shale and tar sands, solar, tides, waste heat, etc. It would be erroneous to search for a universal formula and rational approaches to regionalism through national coordination are indicated. Inevitably, the correct mixture of energies for appropriate uses would be the result of available resources and economic feasibility for any earthly location. Because of the nature of the atmosphere, ambient energies are available globally in varying quantities and each region will need to decide its appropriate use of these energies. Furthermore, because of geographical features, energies are peculiar to a region, which will make their intelligent employment desirable. Hydrogen holds a promising future as a renewable resource energy, and although currently uneconomical to produce, it will be a convenient and desirable replacement for natural gas over the next decades.
Experimental Observations of Non-equilibrium Distributions and Transitions in a 2D Granular Gas

A large number (~10,000) of uniform stainless steel balls comprising less than one layer coverage on a vertically shaken plate provides a rich system for the study of excited granular media. Viewed from above, the horizontal motion in the layer shows interesting collective behavior as a result of inelastic particle- particle collisions. Clusters appear as localized fluctuations from purely random density distributions, as demonstrated by increased particle correlations. The clusters grow as the medium is “cooled” by reducing the rate of energy input. Further reduction of the energy input leads to the nucleation of a collapse: a close-packed crystal of particles at rest. High speed photography allows for measurement of particle velocities between collisions. The velocity distributions deviate strongly from a Maxwell distribution at low accelerations, and show approximately exponential tails, possibly due to an observed cross-correlation between density and velocity fluctuations. When the layer is confined with a lid, the velocity distributions at higher accelerations are non-Maxwellian and independent of the granular temperature.
Introducing dynamic demand response in the LFC model

Demand response (DR) has proved to be an inevitable part of the future grid. Much research works have been reported in the literature on the benefits and implementation of DR. However, little works have been reported on the impacts of DR on dynamic performance of power systems, specifically on the load frequency control (LFC) problem. This paper makes an attempt to fill this gap by introducing a DR control loop in the traditional LFC model (called LFC-DR) for a single-area power system. The model has the feature of optimal operation through optimal power sharing between DR and supplementary control. The effect of DR communication delay in the controller design is also considered. It is shown that the addition of the DR control loop increases the stability margin of the system and DR effectively improves the system dynamic performance. Simulation studies are carried out for single-area power systems to verify the effectiveness of the proposed method.
Pseudo-codeword Landscape

We discuss the performance of low-density-parity-check (LDPC) codes decoded by means of linear programming (LP) at moderate and large signal-to-noise-ratios (SNR). Utilizing a combination of the previously introduced pseudo-codeword-search method and a new "dendro" trick, which allows us to reduce the complexity of the LP decoding, we analyze the dependence of the frame-error-rate (FER) on the SNR. Under maximum-a-posteriori (MAP) decoding the dendro-code, having only checks with connectivity degree three, performs identically to its original code with high-connectivity checks. For a number of popular LDPC codes performing over the additive-white-Gaussian-noise (AWGN) channel we found that either an error-floor sets at a relatively low SNR, or otherwise a transient asymptote, characterized by a faster decay of FER with the SNR increase, precedes the error-floor asymptote. We explain these regimes in terms of the pseudo-codeword spectra of the codes.
SenseRelate targetword: a generalized framework for word sense disambiguation

Many words in natural language have different meanings when used in different contexts. Sense Relate: Target Word is a Perl package that disambiguates a target word in context by finding the sense that is most related to its neighbors according to a WordNet: Similarity measure of relatedness.
Information-Theoretical Learning of Discriminative Clusters for Unsupervised Domain Adaptation

We study the problem of unsupervised domain adaptation, which aims to adapt classifiers trained on a labeled source domain to an unlabeled target domain. Many existing approaches first learn domain-invariant features and then construct classifiers with them. We propose a novel approach that jointly learn the both. Specifically, while the method identifies a feature space where data in the source and the target domains are similarly distributed, it also learns the feature space discriminatively, optimizing an information-theoretic metric as an proxy to the expected misclassification error on the target domain. We show how this optimization can be effectively carried out with simple gradient-based methods and how hyperparameters can be cross-validated without demanding any labeled data from the target domain. Empirical studies on benchmark tasks of object recognition and sentiment analysis validated our modeling assumptions and demonstrated significant improvement of our method over competing ones in classification accuracies.
Output feedback control of inhomogeneous parabolic PDEs with point actuation and point measurement using SOS and semi-separable kernels

In this paper we use Sum-of-Squares (SOS) and Semi-Definite Programming (SDP) to design output feedback controllers for a class of one-dimensional parabolic partial differential equations with point measurements and point actuation. Our approach is based on the use of SOS to search for positive quadratic Lyapunov functions, controllers and observers. These Lyapunov functions, controllers and observers are parameterized by linear operators which are defined by SOS polynomials. The main result of the paper is the development of an improved class of observer-based controllers and evidence which indicates that when the system is controllable and observable, these methods will find a observer-based controller for sufficiently high polynomial degree (similar to well-known results from backstepping).
Topological String Theory on Compact Calabi–Yau: Modularity and Boundary Conditions

The topological string partition function Z(λ,t,t) =exp(λ2 g-2 Fg(t, t)) is calculated on a compact Calabi–Yau M. The Fg(t, t) fulfil the holomorphic anomaly equations, which imply that ψ=Z transforms as a wave function on the symplectic space H3(M, Z). This defines it everywhere in the moduli space M(M) along with preferred local coordinates. Modular properties of the sections Fg as well as local constraints from the 4d effective action allow us to fix Z to a large extent. Currently with a newly found gap condition at the conifold, regularity at the orbifold and the most naive bounds from Castelnuovo’s theory, we can provide the boundary data, which specify Z, e.g. up to genus 51 for the quintic.
Bounds on Sample Size for Policy Evaluation in Markov Environments

Reinforcement learning means finding the optimal course of action in Markovian environments without knowledge of the environment's dynamics. Stochastic optimization algorithms used in the field rely on estimates of the value of a policy. Typically, the value of a policy is estimated from results of simulating that very policy in the environment. This approach requires a large amount of simulation as different points in the policy space are considered. In this paper, we develop value estimators that utilize data gathered when using one policy to estimate the value of using another policy, resulting in much more data-efficient algorithms. We consider the question of accumulating a sufficient experience and give PAC-style bounds.
OCULAR SYMPTOMS OF FAULTY ILLUMINATION

Strain from faulty illumination is thought by the author to be due to the unusual effort necessary to gain greater precision in fixation and focusing on the matter under observation.
Nicht nur den Krebs behandeln, sondern auch die Schmerzen des Patienten

Die erheblichen Fortschritte in der Therapie hamatologischer und onkologischer Erkrankungen bilden sich noch nicht adaquat in der Schmerztherapie bei den betroffenen Patienten ab. Entsprechende Leitlinien sowie die Verpflichtung zur Schmerztherapie wurden formuliert. Wie lassen sich diese Vorgaben in der Praxis umsetzen?
Letter to a Law Student Interested in Social Justice

This a letter to a student interested in social justice law. It explains what to expect, the requirements, successes, and challenges of approaching this practice of law.
Toward Order-of-Magnitude Cascade Prediction

When a piece of information (microblog, photograph, video, link, etc.) starts to spread in a social network, an important question arises: will it spread to "viral" proportions -- where "viral" is defined as an order-of-magnitude increase. However, several previous studies have established that cascade size and frequency are related through a power-law - which leads to a severe imbalance in this classification problem. In this paper, we devise a suite of measurements based on "structural diversity" -- the variety of social contexts (communities) in which individuals partaking in a given cascade engage. We demonstrate these measures are able to distinguish viral from non-viral cascades, despite the severe imbalance of the data for this problem. Further, we leverage these measurements as features in a classification approach, successfully predicting microblogs that grow from 50 to 500 reposts with precision of 0.69 and recall of 0.52 for the viral class - despite this class comprising under 2% of samples. This significantly outperforms our baseline approach as well as the current state-of-the-art. Our work also demonstrates how we can tradeoff between precision and recall.
How much of the labor in African agriculture is provided by women

The contribution of women to labor in African agriculture is regularly quoted in the range of 60 to 80 percent. Using individual-disaggregated, plot-level labor input data from nationally representative household surveys across six Sub-Saharan African countries, this study estimates the average female labor share in crop production at 40 percent. It is slightly above 50 percent in Malawi, Tanzania, and Uganda, and substantially lower in Nigeria (37 percent), Ethiopia (29 percent), and Niger (24 percent). There are no systematic differences across crops and activities, but female labor shares tend to be higher in households where women own a larger share of the land and when they are more educated. Controlling for the gender and knowledge profile of the respondents does not meaningfully change the predicted female labor shares. The findings question prevailing assertions regarding substantial gains in aggregate crop output as a result of increasing female agricultural productivity.
Graph triangulations and the compatibility of unrooted phylogenetic trees

Abstract We characterize the compatibility of a collection of unrooted phylogenetic trees as a question of determining whether a graph derived from these trees — the display graph — has a specific kind of triangulation, which we call legal. Our result is a counterpart to the well-known triangulation-based characterization of the compatibility of undirected multi-state characters.
Exciton and Charge-Transfer Dynamics in Polymer Semiconductors

Organic semiconducting polymers are currently of broad interest as potential low-cost materials for photovoltaic and light-emitting display applications. We will give an overview of our work in developing a consistent quantum dynamical picture of the excited state dynamics underlying the photophysics. We will also focus upon the quantum relaxation and reorganization dynamics that occur upon photoexcitation of a couple of type II donor-acceptor polymer heterojunction systems. Our results stress the significance of vibrational relaxation in the state-to-state relaxation and the impact of curve crossing between charge-transfer and excitonic states. Furthermore, while a tightly bound charge-transfer state (exciplex) remain the lowest excited state, we show that the regeneration of the optically active lowest excitonic state in TFB:F8BT is possible via the existence of a steady-state involving the bulk charge-transfer state. Finally, we will discuss ramifications of these results to recent experimental studied and the fabrication of efficient polymer LED and photovoltaics.
Finite Subgroups of the Plane Cremona Group

This paper completes the classic and modern results on classification of conjugacy classes of finite subgroups of the group of birational automorphisms of the complex projective plane.
Automorphisms of Coxeter groups

We compute Aut(W) for any even Coxeter group whose Coxeter diagram is connected, contains no edges labeled 2, and cannot be separated into more than 2 connected components by removing a single vertex. The description is given explicitly in terms of the given presentation for the Coxeter group and admits an easy characterization of those groups W for which Out(W) is finite.
Challenges for the Nelson-Barr mechanism

The axion and m u = 0 solutions to the strong CP problem have been subject to the most careful scrutiny and critique. Basic theoretical issues include hierarchy and fine-tuning problems, quality and genericity of symmetries, and compatibility with solutions to the electroweak hierarchy problem. We study the similar set of challenges for solutions to strong CP based on spontaneous CP violation and the Nelson-Barr mechanism. Some of our observations have appeared in the literature previously, and others are new; our purpose is to collect and analyze the issues as a whole and provide an assessment of the most plausible settings for the Nelson-Barr solution.
Early stopping and non-parametric regression: an optimal data-dependent stopping rule

Early stopping is a form of regularization based on choosing when to stop running an iterative algorithm. Focusing on non-parametric regression in a reproducing kernel Hilbert space, we analyze the early stopping strategy for a form of gradient-descent applied to the least-squares loss function. We propose a data-dependent stopping rule that does not involve hold-out or cross-validation data, and we prove upper bounds on the squared error of the resulting function estimate, measured in either the L2(P) and L2(Pn) norm. These upper bounds lead to minimax-optimal rates for various kernel classes, including Sobolev smoothness classes and other forms of reproducing kernel Hilbert spaces. We show through simulation that our stopping rule compares favorably to two other stopping rules, one based on hold-out data and the other based on Stein's unbiased risk estimate. We also establish a tight connection between our early stopping strategy and the solution path of a kernel ridge regression estimator.
Concise Synthesis of Annulated Pyrido[3,4-b]indoles via Rh(I)-Catalyzed Cyclization

The synthesis of pyridines bearing multiple ring fusions poses a considerable challenge for organic chemists. To address this problem, we describe the synthesis of a small library of pyrido[3,4-b]indoles via an efficient, five-step sequence. The key transformation is a Rh(I)-catalyzed [2 + 2 + 2] cyclization that forms three rings in one reaction flask. Our method is high yielding, accommodates a variety of functional groups, and suffers no entropic costs as ring size increases.
Providing Efficient I/O Redundancy in MPI Environments

Highly parallel applications often use either highly parallel file systems or large numbers of independent disks. Either approach can provide the high data rates necessary for parallel applications. However, the failure of a single disk or server can render the data useless. Conventional techniques, such as those based on applying erasure correcting codes to each file write, are prohibitively expensive for massively parallel scientific applications because of the granularity of access at which the codes are applied. In this paper we demonstrate a scalable method for recovering from single disk failures that is optimized for typical scientific data sets. This approach exploits coarser-grained (but precise) semantics to reduce the overhead of constructing recovery data and makes use of parallel computation (proportional to the data size and independent of number of processors) to construct data. Experiments are presented showing the efficiency of this approach on a cluster with independent disks, and a technique is described for hiding the creation of redundant data within the MPI-IO implementation.
Benchmarking Global Poverty Reduction

Against what standards should we judge the developing world's overall performance against poverty going forward? The paper proposes two measures, each with both"optimistic"and"ambitious"targets for 2022, 10 years from the time of writing. The first measure is absolute consumption poverty, as judged by what"poverty"means in the poorest countries. The second is a new measure of global poverty combining absolute poverty with country-specific social inclusion needs, consistently with national poverty lines. The optimistic benchmark would entail an absolute poverty rate of 9 percent in 2022, and a combined poverty rate of 40 percent, including the allowance for social inclusion. The more ambitious targets would bring the absolute rate down to 3 percent and the combined rate to 33 percent. The optimistic target would maintain the (impressive) progress against poverty of the last 20 years, without global crises to stall that progress. The ambitious target would require about a 1 percentage point higher growth rate for the gross domestic product of the developing world, as long as this did not come with a reduction in the household sector's share or any further increase in overall inequality beyond its level in 2008. Alternatively, the 3 percent target could be reached at currently expected growth rates but at the lower level of inequality found in 1999.
How to avoid middle income traps ? evidence from Malaysia

Malaysia's structural transformation from low to middle income is a success story, making it one of the most prominent manufacturing exporters' in the world. However, like many other middle income economies, it is squeezed by the competition from low-wage economies on the one hand, and more innovative advanced economies on the other. What can Malaysia do? Does Malaysia need a new growth strategy? This paper emphasizes the need for broad structural transformation; that is, moving to higher productivity production in both goods and services. This paper examines productivity growth for Malaysia at the sectoral level, and constructs several measures of the sophistication of goods and services trade, and puts these comparisons in a global context. The results indicate that Malaysia has further opportunities for growth in the services sector in particular. Modernizing the services sector may provide a way out of the middle income trap, and serve as a source of growth for Malaysia into the future.
How is Tax Policy Conducted over the Business Cycle

It is well known by now that government spending has typically been procyclical in developing economies but a cyclical or countercyclical in industrial countries. Little, if any, is known, however, about the cyclical behavior of tax rates (as opposed to tax revenues, which are endogenous to the business cycle and hence cannot shed light on the cyclicality of tax policy). The authors build a novel dataset on tax rates for 62 countries for the period 1960-2013 that comprises corporate income, personal income, and value-added tax rates. The authors find that, by and large, tax policy is a cyclical in industrial countries but mostly procyclical in developing countries. Further, tax policy in countries with better institutions and or more integrated with world capital markets tends to be less procyclical or more countercyclical.
Complexity of short rectangles and periodicity

The Morse-Hedlund Theorem states that a bi-infinite sequence ? in a finite alphabet is periodic if and only if there exists n ? N such that the block complexity function P ? ( n ) satisfies P ? ( n ) ? n . In dimension two, Nivat conjectured that if there exist n , k ? N such that the n × k rectangular complexity P ? ( n , k ) satisfies P ? ( n , k ) ? n k , then ? is periodic. Sander and Tijdeman showed that this holds for k ? 2 . We generalize their result, showing that Nivat's Conjecture holds for k ? 3 . The method involves translating the combinatorial problem to a question about the nonexpansive subspaces of a certain Z 2 dynamical system, and then analyzing the resulting system.
Analysis of options for increasing pipeline capacity

Natural gas is the preferred fuel for most applications ranging from home heating to electric power production with high efficiency combined cycle power plants. It is competitively priced, relatively easy to transport and results in substantially lower undesirable emissions relative to coal and liquid petroleum. A limiting problem has been availability of pipelines and capacity limits on existing pipelines as was indicated in California in the year 2000. Additional pipelines meet substantial resistance in the approval process. Another option may be to increase the capacity of existing pipelines via higher pressures and additional compressors. This work presents some history, existing practice and projected requirements for the natural gas delivery system. It discusses the analogy between the capacity increase and transmission loss decrease with higher voltages in electric power systems and with higher pressures in gas pipelines. It then performs a fluid dynamic analysis of a reference pipeline to evaluate performance at various capacities. It also evaluates the option of increasing capacity and decreasing compressor power requirements by increasing the pipeline operating pressures.
National Jurisdiction and Global Business Networks

It is a great honor for me to deliver the ninth Snyder Lecture. I have had the pleasure of attending many of the previous lectures delivered in Bloomington by members of the Cambridge faculty. I have also had the pleasure of hearing from those of my students who were given the opportunity to conduct research at the Lauterpacht Centre as Snyder Fellows. Our faculty is very grateful for Earl Snyder’s generosity in supporting these intellectual exchanges between our schools, and I personally am very grateful for this opportunity to address you. I will speak today about the exercise of jurisdiction by U.S. courts over global business networks. There are many ways in which the activities of U.S. courts intersect, and have long intersected, with international business activity, and so this topic calls up in part the procedural issues that are the bread and butter of international civil litigation. U.S. courts regularly assert personal jurisdiction over foreign corporations on the basis of their activities in the United States; they apply U.S. law to foreign conduct that is seen to harm certain interests within the United States; they enforce agreements that send crossborder contract disputes over into the transnational arbitration system. But while some of those practices are mundane and, at least in theory, unobjectionable, others are problematic, and from time to time a specific case or group of cases will trigger a resurgence of attention to the role that U.S. courts play in the international arena. I would point
Sign of refractive index and group velocity in left-handed media

Abstract We argue that the widely spread opinion that the left-handed media (LHM) are characterized by a negative refractive index n − is misleading. Since n does not enter into Maxwell's equations and boundary conditions, any medium may be described by both positive n and negative n − =− n . Two thermodynamic inequalities are presented, that make a difference between the LHM and the regular media (RM). The first one reads that the group velocity is positive in the RM and negative in the LHM. The second one is that the product Re( n )Im( n ) is positive in the RM and negative in the LHM. Both inequalities are invariant with respect to the change n → n − . However, to use n − one should change some traditional electrodynamics definitions.
Galactic X-Ray Sources

Bremsstrahlung and synchrotron hypotheses considered as possible mechanisms for galactic X-ray production
Solution-based chemical synthesis of boehmite nanofibers and alumina nanorods.

This article reports an easy chemical method of synthesizing boehmite nanofibers by a modified sol−gel process involving aluminum isopropoxide precursor. Nanorods of γ-alumina have been successfully prepared after dehydration of the viscous sol at 600 °C for 4 h in air. The boehmite nanofibers and γ-alumina nanorods were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy for surface chemistry and functional groups, scanning electron microscopy, high-resolution transmission electron microscopy with selected area electron diffraction, and energy-dispersed spectroscopy for morphology and structure identification. The length of the boehmite nanofibers was found to be more than 10 μm with a crystalline lattice structure. The mechanism of formation of the boehmite nanofibers included the preferential growth along the longitudinal axis due to interaction between the solvent molecules and the surface OH- groups of hydrogen bonds. It is also suggested that the boehmite nanof...
Stringy K-theory and the Chern character

We construct two new G-equivariant rings: $\mathcal{K}(X,G)$ , called the stringy K-theory of the G-variety X, and $\mathcal{H}(X,G)$ , called the stringy cohomology of the G-variety X, for any smooth, projective variety X with an action of a finite group G. For a smooth Deligne–Mumford stack $\mathcal{X}$ , we also construct a new ring $\mathsf{K}_{\mathrm{orb}}(\mathcal{X})$ called the full orbifold K-theory of $\mathcal{X}$ . We show that for a global quotient $\mathcal{X} = [X/G]$ , the ring of G-invariants $K_{\mathrm{orb}}(\mathcal{X})$ of $\mathcal{K}(X,G)$ is a subalgebra of $\mathsf{K}_{\mathrm{orb}}([X/G])$ and is linearly isomorphic to the “orbifold K-theory” of Adem-Ruan [AR] (and hence Atiyah-Segal), but carries a different “quantum” product which respects the natural group grading. We prove that there is a ring isomorphism $\mathcal{C}\mathbf{h}:\mathcal{K}(X,G)\to\mathcal{H}(X,G)$ , which we call the stringy Chern character. We also show that there is a ring homomorphism $\mathfrak{C}\mathfrak{h}_\mathrm{orb}:\mathsf{K}_{\mathrm{orb}}(\mathcal{X}) \rightarrow H^\bullet_{\mathrm{orb}}(\mathcal{X})$ , which we call the orbifold Chern character, which induces an isomorphism $Ch_{\mathrm{orb}}:K_{\mathrm{orb}}(\mathcal{X})\rightarrow H^\bullet_{\mathrm{orb}}(\mathcal{X})$ when restricted to the sub-algebra $K_{\mathrm{orb}}(\mathcal{X})$ . Here $H_{\mathrm{orb}}^\bullet(\mathcal{X})$ is the Chen–Ruan orbifold cohomology. We further show that $\mathcal{C}\mathbf{h}$ and $\mathfrak{C}\mathfrak{h}_\mathrm{orb}$ preserve many properties of these algebras and satisfy the Grothendieck–Riemann–Roch theorem with respect to etale maps. All of these results hold both in the algebro-geometric category and in the topological category for equivariant almost complex manifolds. We further prove that $\mathcal{H}(X,G)$ is isomorphic to Fantechi and Gottsche’s construction [FG, JKK]. Since our constructions do not use complex curves, stable maps, admissible covers, or moduli spaces, our results greatly simplify the definitions of the Fantechi–Gottsche ring, Chen–Ruan orbifold cohomology, and the Abramovich–Graber–Vistoli orbifold Chow ring. We conclude by showing that a K-theoretic version of Ruan’s Hyper-Kahler Resolution Conjecture holds for the symmetric product of a complex projective surface with trivial first Chern class.
New approach to teaching an introductory computer science course

In this work, we report our results based on an innovative approach that we started three years ago for delivering an introductory computer science course. The teaching approach consisted of team teaching, hybrid delivery, recorded lecture retrieval capability, readiness assessment activities, post assessment activities, objective assessment of student progress, and cooperative learning through team work. The new aspects of this approach were team teaching, objective assessment to provide additional feedback to students, and the combination of the aforementioned tools. Details of this work, including its advantages, disadvantages, student feedback, and lessons learned, are included.
A meta-analysis of estimates of the impact of technical barriers to trade

Abstract A meta-analysis explains the variation in estimated trade effects of technical barriers to trade broadly defined, using available estimates from the empirical international trade literature, and accounting for data sampling and methodology differences. Agriculture and food industries tend to be more impeded by these barriers than other sectors. SPS regulations on agricultural and food trade flows from developing exporters to high-income importers tend to impede trade. Not controlling for “multilateral resistance” barriers increase the likelihood to overstate the trade impeding effect of technical measures and not accounting for their potential endogeneity with trade does the opposite. Studies using direct maximum residue limits tend to find more trade impeding effects than other measures and clearer policy implications. Other technical measures proxies tend to muddle results and increase the likelihood of inconclusive results and few policy implications.
ENHANCED ROBUSTNESS IN INTEGRATED STRUCTURAL/CONTROL SYSTEMS DESIGN

This paper addresses maximizing the robustness of an integrated structural/control system for increasing the stability margin under parametric uncertainties. The robustness limit is defined for a linear time-invariant system consisting of structured perturbations. The optimization problem has considered the closed-loop eigenvalues, damping parameter, and robustness as design constraints. Effects of increasing the stability robustness of a closed-loop system are demonstrated on two structural optimization examples.
Vortex-induced vibration of a heavy-lift launch vehicle during transonic flight

Abstract The Titan IV, like many other heavy-lift launch vehicles, is composed of three bodies. At Mach 1.1, 17-Hz pressure oscillations have been observed on the Titan IV center body. The associated lateral structural responses often exceed in amplitude those for all other flight events. Computational fluid dynamic (CFD) simulations conducted for the Titan IV show that pairs of vortices are shed due to strong crossflow acceleration towards the center body, and that these vortex pairs form periodically on alternate sides of the launch vehicle. The phenomenon is analogous to von Karman vortex shedding over a cylinder, with Strouhal number 0.14–0.17. The CFD simulations were used to generate forcing functions for structural dynamic analyses. The resulting structural responses are in good agreement with transonic flight measurements. The structural dynamic analyses also show that the degree of alignment of the aerodynamic force amplitudes with the mission-specific structural mode shapes has a strong effect on the flight responses.
Guaranteed clustering and biclustering via semidefinite programming

Identifying clusters of similar objects in data plays a significant role in a wide range of applications. As a model problem for clustering, we consider the densest $$k$$ k -disjoint-clique problem, whose goal is to identify the collection of $$k$$ k disjoint cliques of a given weighted complete graph maximizing the sum of the densities of the complete subgraphs induced by these cliques. In this paper, we establish conditions ensuring exact recovery of the densest $$k$$ k cliques of a given graph from the optimal solution of a particular semidefinite program. In particular, the semidefinite relaxation is exact for input graphs corresponding to data consisting of $$k$$ k large, distinct clusters and a smaller number of outliers. This approach also yields a semidefinite relaxation with similar recovery guarantees for the biclustering problem. Given a set of objects and a set of features exhibited by these objects, biclustering seeks to simultaneously group the objects and features according to their expression levels. This problem may be posed as that of partitioning the nodes of a weighted bipartite complete graph such that the sum of the densities of the resulting bipartite complete subgraphs is maximized. As in our analysis of the densest $$k$$ k -disjoint-clique problem, we show that the correct partition of the objects and features can be recovered from the optimal solution of a semidefinite program in the case that the given data consists of several disjoint sets of objects exhibiting similar features. Empirical evidence from numerical experiments supporting these theoretical guarantees is also provided.
Enantioselective Total Synthesis of Eunicenone A

An enantioselective, stereocontrolled total synthesis of eunicenone A (1) is described starting from geranylgeranylacetylene (9) in 14 steps via intermediates 10-20. The most critical construction in the synthesis is the highly effective Diels-Alder combination of the achiral components 2-bromoacrolein and diene 13 in the presence of the chiral Lewis acid catalyst 14 to form 15 (85% yield, 97% ee, >98:2 endo-exo ratio). The synthesis utilizes a novel reagent (12) for introduction of silicon, which serves to activate and direct the diene 13 for Diels-Alder reaction and to provide for eventual oxygen functionality of homoallylic alcohol 17 under mild conditions. Other noteworthy steps include the position selective and diastereoselective epoxidation 17 --> 18, the methoxycarbonylation with allylic transposition 19 --> 20, and the alpha,beta-enone unmasking 20 --> 1.
Heart rate changes caused by chemical stimulation of the amygdaloid body.

Abstract The modification of cardiovascular parameters resulting from the injection of norepinephrine (NE) or acetylcholine (ACh) into the amygdala was investigated in the chronically prepared unanesthetized restrained beagle. Blood pressure was obtained via an aortic catheter while heart rate was determined from Lead II of the ECG. Depth electrodes implanted into the hippocampus and ventromedial hypothalamus were used to record the EEG from these respective sites. NE caused a dose-related decrease in heart rate while ACh induced a tachycardia of short duration. Methyl atropine injected into the amygdala prior to ACh blocked the ACh induced tachycardia while physostigmine mimicked the cholinergic response. These responses were not associated with changes in blood pressure or respiration. It is concluded that there are two chemically coded systems within the amygdaloid body that are capable of modifying heart rate: an adrenergic system that induces bradycardia and a cholinergic system that causes tachycardia.
American Studies and the University of Debt

Response to 2013 American Studies Association Presidential Address by Curtis Marez.In his presidential address, Curtis Marez articulates an ambitious double project for himself and for the field: to “center collective dissent to student debt in American studies” and “to outline an American studies version of critical university studies.” As the address unfolds, he successfully demonstrates that many of the richest areas of scholarship in American studies in recent decades — such as explorations of the constitution of racial, gendered, and class subjectivities, identities, and hierarchies; and the transnational processes and relations in which the United States is situated — could and/or should, if they have not done so already, engage debt, and in particular “student debt,” “university debt,” “the university of debt,” as a constitutive force such that “the contemporary regime of university debt constitutes a form of racialized and gendered settler colonial capitalism.”
Towards hard x-ray imaging at GHz frame rate

Gigahertz (GHz) imaging using hard x-rays (≳10 keV) can be useful to high-temperature plasma experiments, as well as research and applications using coherent photons from synchrotron radiation and x-ray free electron lasers. GHz framing rate can be achieved by using multiple cameras through multiplexing. The advantages and trade-offs of single-photon detection mode, when no more than one x-ray photon is detected per pixel, are given. Two possible paths towards x-ray imaging at GHz frame rates using a single camera are: (a) avalanche photodiode arrays of high-Z materials and (b) microchannel plate photomultipliers in conjunction with materials with large indices of refraction.
Overview of impurity control and wall conditioning in NSTX

The national spherical torus experiment (NSTX) started plasma operations in February 1999. In the first extended period of experiments, NSTX achieved high current, inner wall limited, double null, and single null plasma discharges, initial Coaxial Helicity Injection, and high harmonic fast wave results. As expected, discharge reproducibility and performance were strongly affected by wall conditions. In this paper, we describe the internal geometry, and initial plasma discharge, impurity control, wall conditioning, erosion, and deposition results.
Small‐Angle Neutron Scattering from Porosity in Sintered Alumina

A new approach for studying porosity in ceramic or metallic materials has been developed using multiple neutron scattering in the small-angle regime. This technique enables the measurement of voids from 0.08 to 10 μm in size with 1% to 50% porosity. Whereas a fully dense alumina sample showed no evidence of multiple neutron-scattering effects, a more porous alumina exhibited striking neutron wavelength dependence. The voids in the latter material are 1.48 μm in mean diameter and 10.5% in volume fraction.
Hubble Space Telescope Images of Submillimeter Sources: Large Irregular Galaxies at High Redshift

We present new Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) high-resolution optical imaging of a sample of 13 submillimeter luminous galaxies for which the optical emission has been pinpointed either through radio 1.4 GHz or millimeter interferometry. We find a predominance of irregular and complex morphologies in the sample, suggesting that mergers are likely common for submillimeter galaxies. The component separations in these objects are on average a factor 2 larger than in local galaxies with similarly high bolometric luminosities. The sizes and star formation rates of the submillimeter galaxies are consistent with the maximal star formation rate densities of 20 M? kpc-2 in local starburst galaxies (Lehnert & Heckman). We derive quantitative morphological information for optical galaxies hosting submillimeter emission: total and isophotal magnitudes, Petrosian radius, effective radius, concentration, aspect ratio, surface brightness, and asymmetry. We compare these morphological indexes with those of other galaxies lying within the same STIS images. Most strikingly, we find ~70% of the submillimeter galaxies to be extraordinarily large and elongated relative to the field population, regardless of optical magnitude. Comparison of the submillimeter galaxy morphologies with those of optically selected galaxies at z ~ 2-3 reveals the submillimeter galaxies to be a morphologically distinct population, with generally larger sizes, higher concentrations, and more prevalent major-merger configurations.
The crack problem for an orthotropic half-plane stiffened by elastic films

Abstract In this paper, various contact and crack problems for an orthotropic substrate, stiffened by elastic films, are considered. The film is modeled as a membrane and the substrate as an orthotropic half-plane with the principal axes of orthotropy parallel and perpendicular to the boundary. The problem is formulated in terms of a system of singular integral equations. Various asymptotic analyses are carried out in order to determine the nature of the stresses singularities. The special cases for which the solution is obtained and results are provided include the stiffened half-plane without the crack, the cracked half-plane without any stiffeners, the orthotropic half-plane with a single stiffener and a crack emanating from the endpoint of the stiffener, and a broken stiffener on a cracked half-plane. In each case the influence of the relative crack/stiffener dimensions, the film/substrate stiffness ratios, and the material orthotropy on the stress intensity factors is studied and some sample results are given.
Evolution of the Cluster Correlation Function

We study the evolution of the cluster correlation function and its richness dependence from z = 0 to z = 3 using large-scale cosmological simulations. A standard flat LCDM model with Ωm = 0.3 and, for comparison, a tilted Ωm = 1 model (TSCDM) are used. The evolutionary predictions are presented in a format suitable for direct comparisons with observations. We find that the cluster correlation strength increases with redshift: high-redshift clusters are clustered more strongly (on a comoving scale) than low-redshift clusters of the same mass. The increased correlation with redshift, in spite of the decreasing mass correlation strength, is caused by the strong increase in cluster bias with redshift: clusters represent higher density peaks of the mass distribution as the redshift increases. The richness-dependent cluster correlation function, presented as the correlation scale versus cluster mean separation relation, R0-d, is found to be, remarkably, independent of redshift to z 2 for LCDM and z 1 for TSCDM for a fixed correlation function slope and a cluster mass within a fixed comoving radius. The nonevolving R0-d relation implies that both the comoving clustering scale and the cluster mean separation increase with redshift for the same mass clusters, so that the R0-d relation remains essentially unchanged. For LCDM, this relation is R0(z) 2.6 1/2 for z 2 in comoving h-1 Mpc scales. The TSCDM model has smaller correlation scales, as expected. Evolution in the relation is seen at z 2 for LCDM and z 1 for TSCDM, where the amplitude of the relations declines. The evolution of the R0-d relation from z ~ 0 to z ~ 3 provides an important new tool in cosmology; it can be used to break degeneracies that exist at z ~ 0 and provide precise determination of cosmological parameters.
Transitional Phases at Ceramic–Metal Interfaces: Orthorhombic, Cubic, and Hexagonal Ti‐Si‐Cu‐N Compounds

Reaction products at the boundary between Si{sub 3}N{sub 4} and Ag-Cu-Ti braze alloy have been characterized by transmission electron microscopy. Beyond the TiN adjoining the Si{sub 3}N{sub 4} substrate is a continuous layer of a previously unreported, orthorhombic Ti-Si-Cu-N compound. Evidence of additional cubic and hexagonal Ti-Si-Cu-N phases is also found; these exist as isolated grains farther from the substrate. The cubic compound is probably an {eta}-type M{sub 6}X phase of the sort observed at other ceramic-metal interfaces. These dilute ceramics, in which metallic constituents dominate, are common transitional phases in ceramic-metal systems.