cssi/SciSciGPT-SciSciNet huggingface dataset:
Pronounced Negative Thermal Expansion from a Simple Structure: Cubic ScF3

Scandium trifluoride maintains a cubic ReO(3) type structure down to at least 10 K, although the pressure at which its cubic to rhombohedral phase transition occurs drops from >0.5 GPa at ∼300 K to 0.1-0.2 GPa at 50 K. At low temperatures it shows strong negative thermal expansion (NTE) (60-110 K, α(l) ≈ -14 ppm K(-1)). On heating, its coefficient of thermal expansion (CTE) smoothly increases, leading to a room temperature CTE that is similar to that of ZrW(2)O(8) and positive thermal expansion above ∼1100 K. While the cubic ReO(3) structure type is often used as a simple illustration of how negative thermal expansion can arise from the thermally induced rocking of rigid structural units, ScF(3) is the first material with this structure to provide a clear experimental illustration of this mechanism for NTE.
The impacts of the Luni‐Solar oscillation on the Arctic oscillation

[1] The Arctic Oscillation (AO) has a major impact on climate variability in the extra tropical regions of the Northern Hemisphere. In this study, we show that specific alignments between the Sun, the Moon and the Earth known as the Luni-Solar Oscillation (LSO) that occur at frequencies of nearly 9 and 18 years are unambiguously correlated with the AO since the mid-1960's. The occurrence of the LSO peaks is predictable and, as a result, it improves climate predictability. Furthermore, we hypothesize that the recent observed increase in the AO amplitude maybe due to ice melting in the Arctic and SST increases at northern latitudes combined with the recent LSO peaks.
ACE: Exploiting Correlation for Energy-Efficient and Continuous Context Sensing

We propose an acquisitional context engine (ACE), a middleware that supports continuous context-aware applications while mitigating sensing costs for inferring contexts. The ACE provides user's current context to applications running on it. In addition, it dynamically learns relationships among various context attributes (e.g., whenever the user is Driving, he is not AtHome). The ACE exploits these automatically learned relationships for two powerful optimizations. The first is inference caching that allows the ACE to opportunistically infer one context attribute (AtHome) from another already-known attribute (Driving), without acquiring any sensor data. The second optimization is speculative sensing that enables the ACE to occasionally infer the value of an expensive attribute (e.g., AtHome) by sensing cheaper attributes (e.g., Driving). Our experiments with two real context traces of 105 people and a Windows Phone prototype show that the ACE can reduce sensing costs of three context-aware applications by about 4.2 times, compared to a raw sensor data cache shared across applications, with a very small memory and processing overhead.
Adaptive compressive sensing algorithm for video acquisition using a single-pixel camera

We propose a method to acquire compressed measurements for efficient video reconstruction using a single-pixel camera. The method is suitable for implementation using a single-pixel detector, along with a digital micromirror device or other types of spatial light modulators. Conventional implementations of single-pixel cameras are able to spatially compress the signal, but the compressed measurements make it difficult to exploit temporal redundancies directly. Moreover, a single-pixel camera needs to make measurements in a sequential manner before the scene changes, making it inefficient for video imaging. We discuss a measurement scheme that exploits sparsity along the time axis for video imaging. After acquiring all measurements required for the first frame, measurements are acquired only from the areas that change in subsequent frames. We segment the first frame, detect the magnitude and direction of change for each segment, and acquire compressed measurements for the changing segments in the predicted direction. Next, we compare the reconstruction results for a few test sequences with existing techniques and demonstrate the practical utility of the scheme.
Polarimetry with a soft x-ray spectrometer

National Aeronautics and Space Administration (Smithsonian Astrophysical Observatory contract SV3-73016)
Learning Correlations between Linguistic Indicators and Semantic Constraints: Reuse of Context-Dependent Descriptions of Entities

This paper presents the results of a study on the semantic constraints imposed on lexical choice by certain contextual indicators. We show how such indicators are computed and how correlations between them and the choice of a noun phrase description of a named entity can be automatically established using supervised learning. Based on this correlation, we have developed a technique for automatic lexical choice of descriptions of entities in text generation. We discuss the underlying relationship between the pragmatics of choosing an appropriate description that serves a specific purpose in the automatically generated text and the semantics of the description itself. We present our work in the framework of the more general concept of reuse of linguistic structures that are automatically extracted from large corpora. We present a formal evaluation of our approach and we conclude with some thoughts on potential applications of our method.
LOCALISATION OF DAMAGE IN SMART STRUCTURES THROUGH SENSITIVITY ENHANCING FEEDBACK CONTROL

Abstract The concept of sensitivity enhancing control (SEC) introduced previously by the authors exploits the relationship between feedback control gains and classic measures of root and system sensitivity in order to increase the magnitude of variation in modal characteristics when damage occurs. This paper further develops the SEC concept, focusing on the ability tolocate damage in smart structures. Two distinct methods are considered for locating damage. Forward methods rely on a priori knowledge of how certain damage scenarios affect modal properties. Using this information, the correlation between measured modal frequency shifts and predicted modal frequency shifts for a given set of damage scenarios is used to identify damage location. Inverse, or model updating methods attempt to update mass and/or stiffness matrices of structural models based on measured modal frequencies and mode shapes. The resulting perturbation matrices indicate damage location. Here, both methods are evaluated through finite-element simulation of controlled structures with local stiffness damage, with the goal of determining whether inclusion of modal data from feedback controlled structures enhances the localisation process. Results show that application of both forward and inverse methods to measured closed-loop modal characteristics increases both the accuracy with which stiffness damage can be located and the ability to tolerate noise in measurement of modal properties used to locate damage.
Photochemical hydrolysis of o-acetylphenylacetonitriles

Irradiation of 1 and its methyl derivative 10a (λ >280 nm) in methanol leads to photohydrolysis of the nitrile group and formation of the related ketal amides 3 and 11a, respectively Similar treatment of the dimethyl derivative 10b and of the parent nitrile 13 fails to yield corresponding products of hydrolysis. A mechanism is proposed for these novel hydrolyses.
A Consistent Test of Stationary Ergodicity

A formal statistical test of stationary-ergodicity is developed for known Markovian processes on R^d. This makes it applicable to testing models and algorithms, as well as estimated time series processes ignoring the estimation error. The analysis is conducted by examining the asymptotic properties of the Markov operator on density space generated by the transition in the state space. The test is developed under the null of stationary-ergodicity, and it is shown to be consistent against the alternative of nonstationary-ergodicity. The test can be easily performed using any of a number of standard statistical and mathematical computer packages.
Strategic network interdiction

We develop a strategic model of network interdiction. Given a network, an agency faces an adversary. The adversary chooses how to carry bads through the network from a base to a target. By carrying bads, the adversary can damage the target. Simultaneously, the agency chooses which arcs to block in the network. By blocking arcs, the agency can decrease the amount of bads carried to the target. However, the blockage of arcs disrupts the operation of the network. The adversary gains from the target damage and the network disruption while the agency loses from them. The adversary incurs the expense of carrying bads. We find Nash equilibria of this model. When the marginal loss of the target is no greater than the marginal expense of carrying bads, there are pure strategy Nash equilibria in which the adversary carries no bads from the base to the target and the agency blocks no arcs. When the marginal loss of the target is greater than the marginal expense of carrying bads, there are mixed strategy Nash equilibria in which the adversary carries certain amounts of bads with positive probability and the agency blocks no arcs with positive probability. We then calculate the equilibrium probabilities of the adversary damaging the target. These equilibrium probabilities turn out to be negative power functions of the marginal target loss.
Why Proving HIBE Systems Secure Is Difficult

Proving security of Hierarchical Identity-Based Encryption (HIBE) and Attribution Based Encryption scheme is a challenging problem. There are multiple well-known schemes in the literature where the best known (adaptive) security proofs degrade exponentially in the maximum hierarchy depth. However, we do not have a rigorous understanding of why better proofs are not known. (For ABE, the analog of hierarchy depth is the maximum number of attributes used in a ciphertext.)
Making Sense of Nonsense: The Visual Salience of Units Determines Sensitivity to Magnitude

When are people sensitive to the magnitude of numerical information presented in unfamiliar units, such as a price in a foreign currency or a measurement of an unfamiliar product attribute? We propose that people exhibit deliberational blindness, a failure to consider the meaning of even unfamiliar units. When an unfamiliar unit is not salient, people fail to take their lack of knowledge into account, and their judgments reflect sensitivity to the magnitude of the number. However, subtly manipulating the visual salience of the unit (e.g., enlarging its font size relative to the font size of the number) prompts recognition of the unit’s unfamiliarity and reduces magnitude sensitivity. In five experiments, we demonstrated this unit-salience effect, provided evidence for deliberational blindness, and ruled out alternative explanations, such as nonperception and fluency. These findings have implications for decision making involving numerical information expressed in both unfamiliar units and familiar but poo...
Augmented reality: hard problems of law and policy

Augmented reality (AR) technologies are poised to enter the commercial mainstream. Using an interdisciplinary research team, we describe our vision of AR and explore the unique and difficult problems AR presents for law and policy---including around privacy, free speech, discrimination, and safety.
A Debate beyond Sexuality: “Tradition,” Human Rights and Uganda's Gay Death Penalty

In the fall of 2009, MP David Bahati introduced a bill to Uganda’s Parliament proposing tighter strictures on expressions of homosexuality, which were already outlawed in Uganda by the 1950 penal code and 1995 Constitution. The Anti-Homosexuality Bill quickly gained attention in the US media, whose own “culture wars” have been raging over the question of same-sex marriage. Most notable in the bill was the provision that gay Ugandans could actually be put to death for “aggravated homosexuality”—meaning committing same-sex acts with a minor, family member or disabled person—or where the “aggressor” is HIV-positive. Further, the bill would make it obligatory for people who “discover” another’s homosexuality to inform on them. Those who failed to do so would face jail time. The media have made much of US evangelical influence on Uganda’s civic and political leaders, citing incidents like Defend the Family’s Scott Lively speaking at a 2009 three-day “Seminar on Exposing the Homosexual Agenda” in Kampala as the inspiration for this bill. Ugandan leaders have taken offense at suggestions that they’ve caved to missionary neocolonialism. Instead, many regard homosexuality as the latest insidious Western colonial imposition that must be resisted. I suggest that there is much more at work here than a debate about cultural values, or even sexuality. Central to this issue are questions of reproduction, tradition and human rights. The perceived threat in Uganda isn’t homosexuality alone, and Bahati’s bill is not just a result of the anti-homosexual fervor whipped up by American neoconservative evangelicals. As Marc Epprecht discussed in Heterosexual Africa? (2008), there’s a long history of denial of African homosexuality. I argue that one could view the debate as a moral panic connected to the overwhelming concern with fertility in Ugandan society. Herdt et al (Moral Panics, Sex Panics 2009) have pointed out that sexual issues are often at the center of moral panics, but that they tend to reflect wider concerns with societal change. With the second highest fertility rate in the world, Ugandans take fertility seriously, often using it as a barometer of national security. Many countries view a steady birth
On The Power of Membership Queries in Agnostic Learning

We study the properties of the agnostic learning framework of Haussler (1992) and Kearns, Schapire, and Sellie (1994). In particular, we address the question: is there any situation in which membership queries are useful in agnostic learning? Our results show that the answer is negative for distribution-independent agnostic learning and positive for agnostic learning with respect to a specific marginal distribution. Namely, we give a simple proof that any concept class learnable agnostically by a distribution-independent algorithm with access to membership queries is also learnable agnostically without membership queries. This resolves an open problem posed by Kearns et al. (1994). For agnostic learning with respect to the uniform distribution over {0,1}n we show a concept class that is learnable with membership queries but computationally hard to learn from random examples alone (assuming that one-way functions exist).
Hemodynamics during General Anesthesia in Patients Receiving Propranolol

To determine whether orally administered propranolol contributes to untoward hemodynamic function during general anesthesia, the authors divided patients undergoing myocardial revascularization into two groups: One group (n = 9) did not receive propranolol orally in the preoperative period. The othe
Boolean Compressed Sensing and Noisy Group Testing

The fundamental task of group testing is to recover a small distinguished subset of items from a large population while efficiently reducing the total number of tests (measurements). The key contribution of this paper is in adopting a new information-theoretic perspective on group testing problems. We formulate the group testing problem as a channel coding/decoding problem and derive a single-letter characterization for the total number of tests used to identify the defective set. Although the focus of this paper is primarily on group testing, our main result is generally applicable to other compressive sensing models.
Intramolecular C(sp3)-N coupling by oxidation of benzylic C,N-dianions.

The ability to effect direct, carbon–nitrogen (C–N) bond formation between an N–H group and a C(sp3)–H group by the formal loss of H2 would significantly enhance the existing toolbox of synthetic methods to build complex nitrogen-containing molecules. Such a transformation, particularly involving N,N-dialkyl secondary amines, would serve as a complement to processes such as reductive amination and would obviate the requirement of a preoxidized coupling partner (e.g., a carbonyl group). Although the Hoffman-Loffler-Freytag (HLF) reactioni and its associated modern variantsii offer one such alternative, preoxidation of the nitrogen partner is usually required and success remains limited to the formation of specific ring sizes. For example, while five-membered rings are readily formed using the HLF reaction, 6- and 7-membered rings are more difficult to obtain. Thus, a general, one-pot, C(sp3)–N coupling reaction would be highly desirable.iii, iv, v
Directed test generation using symbolic grammars

We present CESE, a tool that combines exhaustive enumeration of test inputs from a structured domain with symbolic execution driven test generation. We target programs whose valid inputs are determined by some context free grammar. We abstract the concrete input syntax with symbolic grammars, where some original tokens are replaced with symbolic constants. This reduces the set of input strings that must be enumerated exhaustively. For each enumerated input string, which may contain symbolic constants, symbolic execution based test generation instantiates the constants based on program execution paths. The "template" generated by enumerating valid strings reduces the burden on the symbolic execution to generate syntactically valid inputs and helps exercise interesting code paths. Together, symbolic grammars provide a link between exhaustive enumeration of valid inputs and execution-directed symbolic test generation Preliminary experiments with CESE show that the combination achieves better coverage than both pure enumerative test generation and pure directed symbolic test generation, in orders of magnitude less time and number of generated inputs. In addition, CESE is able to automatically generate inputs that achieve coverage within 10% of manually constructed tests.
Small exotic 4–manifolds

In this article, we construct the first example of a simply-connected minimal symplectic 4-manifold that is homeo- morphic but not diffeomorphic to 3CP 2 #7CP 2 . We also construct the first exotic minimal symplectic CP 2 #5 CP 2 .
Simulation of electronic structure Hamiltonians using quantum computers

Over the last century, a large number of physical and mathematical developments paired with rapidly advancing technology have allowed the field of quantum chemistry to advance dramatically. However, the lack of computationally efficient methods for the exact simulation of quantum systems on classical computers presents a limitation of current computational approaches. We report, in detail, how a set of pre-computed molecular integrals can be used to explicitly create a quantum circuit, i.e. a sequence of elementary quantum operations, that, when run on a quantum computer, obtains the energy of a molecular system with fixed nuclear geometry using the quantum phase estimation algorithm. We extend several known results related to this idea and discuss the adiabatic state preparation procedure for preparing the input states used in the algorithm. With current and near future quantum devices in mind, we provide a complete example using the hydrogen molecule of how a chemical Hamiltonian can be simulated using ...
Quantifying the effect of sentiment on information diffusion in social media

Social media have become the main vehicle of information production and consumption online. Millions of users every day log on their Facebook or Twitter accounts to get updates and news, read about their topics of interest, and become exposed to new opportunities and interactions. Although recent studies suggest that the contents users produce will affect the emotions of their readers, we still lack a rigorous understanding of the role and effects of contents sentiment on the dynamics of information diffusion. This work aims at quantifying the effect of sentiment on information diffusion, to understand: (i) whether positive conversations spread faster and/or broader than negative ones (or vice-versa); (ii) what kind of emotions are more typical of popular conversations on social media; and, (iii) what type of sentiment is expressed in conversations characterized by different temporal dynamics. Our findings show that, at the level of contents, negative messages spread faster than positive ones, but positive ones reach larger audiences, suggesting that people are more inclined to share and favorite positive contents, the so-called positive bias. As for the entire conversations, we highlight how different temporal dynamics exhibit different sentiment patterns: for example, positive sentiment builds up for highly-anticipated events, while unexpected events are mainly characterized by negative sentiment. Our contribution is a milestone to understand how the emotions expressed in short texts affect their spreading in online social ecosystems, and may help to craft effective policies and strategies for content generation and diffusion.
Pebbling Graphs of Diameter Three and Four

Given a configuration of pebbles on the vertices of a connected graph G, a pebbling move is defined as the removal of two pebbles from some vertex and the placement of one of these on an adjacent vertex. The pebbling number of a graph G is the smallest integer k such that for each vertex v and each configuration of k pebbles on G there is a sequence of pebbling moves that places at least one pebble on v. We improve on a bound of Bukh by showing that the pebbling number of a graph of diameter three on n vertices is at most , and this bound is best possible. Further, we obtain an asymptotic bound of for the pebbling number of graphs of diameter four. Finally, we prove an asymptotic bound for pebbling graphs of arbitrary diameter, namely that the pebbling number for a diameter d graph on n vertices is at most , where is a constant depending upon d. This also improves another bound of Bukh.
Thin and lumpy: An experimental investigation of water quality trading

Abstract Water quality trading schemes have generally not delivered the volume of cost-reducing trading activity that would warrant declaring them a success. In this paper we utilize laboratory economics experiments to explore the extent to which market outcomes are influenced by the technology through which pollution abatement is achieved. Mirroring the majority of point-source water quality trading markets, the sessions utilize small trading groups composed of six participants. In a departure from the majority of emissions trading experiments, participants are able to choose both their abatement technology as well as their abatement effort. To understand the extent to which technological considerations influence investment and trading behavior, the treatments vary the degree of heterogeneity in initial pollution abatement costs, the potential for long-lived investments in cost-reducing abatement technology, and limits to specific abatement technologies. Our results reveal over-investment in abatement technology across a range of treatment scenarios, especially when participants face limited abatement opportunities with the conventional technology and are risk averse. The results also illustrate the important relationship between investment behavior and observed transaction volume and market prices.
Phase-only shaped beam synthesis via technique of approximated beam addition

A new method for phase-only phased-array beam-pattern synthesis is derived. The method is appropriate for the synthesis of coverage patterns for satellite communications, where a minimax goal of maximizing the worst-case beamforming gain to a set of service locations is desired. The new approach, called the technique of approximated beam addition, is found to be computationally attractive relative to conventional methods, yet offers optimal performance. Included are a theoretical consideration of optimality and simulation examples comparing the computational complexity and convergence quality to that of proven techniques.
Do Scientists Pay to Be Scientists

This paper explores the relationship between wages and the scientific orientation of R&D organizations. Firms that adopt a science-oriented research approach (i.e., "science") allow their researchers to pursue and publish an individual research agenda. The adoption of science may be associated with a "taste" for science on the part of researchers (a preference effect) and/or as a "ticket of admission" to gain earlier access to scientific discoveries with commercial application (a productivity effect). These two effects differ in their impact on wages. Whereas the preference effect contributes to a negative compensating differential, the productivity effect may result in rent sharing. However, because science may be adopted by firms employing higher-quality researchers, cross-sectional evaluations of wages and science may be biased by unobserved heterogeneity. To overcome this bias, this paper introduces a novel empirical approach. Specifically, prior to accepting a given job, many scientists receivemultiple job offers, allowing for the calculation of the wage-science relationship and controlling for differences in salary levels offered to individual researchers. Using a dataset composed of multiple job offers to postdoctoral biologists, the results suggest a negative relationship between wages and science. These findings are robust to restricting the sample to nonacademic job offers, but the findings depend critically on the inclusion of researcher fixed effects. Conditional on perceived ability, scientists do indeedpay to be scientists.
Adaptive Filtering For Image Enhancement

In this paper, we develop an image enhancement algorithm that modifies the local luminance mean of an image and controls the local contrast as a function of the local luminance mean of the image. The algorithm first separates an image into its lows (low-pass filtered form) and highs (high-pass filtered form) components. The lows component then controls the amplitude of the highs component to increase the local contrast. The lows component is then subjected to a nonlinearity to modify the local luminance mean of the image and is combined with the processed highs component. The performance of this algorithm when applied to enhance typical undegraded images, images with large shaded areas, and also images degraded by cloud cover will be illustrated by way of examples.
Structurally unambiguous finite automata

We define a structurally unambiguous finite automaton (SUFA) to be a nondeterministic finite automaton (NFA) with one starting state q0 such that for all input strings w and for any state q, there is at most one path from q0 to q that consumes w. The definition of SUFA differs from the usual definition of an unambiguous finite automaton (UFA) in that the new definition is defined in terms of the transition logic of the finite automaton, and is independent of the choice of final states. We show that SUFA can be exponentially more succinct in the number of states than UFA and MDFA (deterministic finite automata with multiple initial states). Some interesting examples of SUFA are given. We argue that SUFA is a meaningful concept, and can have practical importance as it can implemented efficiently on synchronous models of parallel computation.
Straight line orbits in Hamiltonian flows

We investigate straight-line orbits (SLO) in Hamiltonian force fields using both direct and inverse methods. A general theorem is proven for natural Hamiltonians quadratic in the momenta for arbitrary dimensions and is considered in more detail for two and three dimensions. Next we specialize to homogeneous potentials and their superpositions, including the familiar Henon–Heiles problem. It is shown that SLO’s can exist for arbitrary finite superpositions of N-forms. The results are applied to a family of potentials having discrete rotational symmetry as well as superpositions of these potentials.
Distributed Source Coding in the Presence of Byzantine Sensors

The distributed source coding problem is considered when the sensors, or encoders, are under Byzantine attack; that is, an unknown group of sensors have been reprogrammed by a malicious intruder to undermine the reconstruction at the fusion center. Three different forms of the problem are considered. The first is a variable-rate setup, in which the decoder adaptively chooses the rates at which the sensors transmit. An explicit characterization of the variable-rate achievable sum rates is given for any number of sensors and any groups of traitors. The converse is proved constructively by letting the traitors simulate a fake distribution and report the generated values as the true ones. This fake distribution is chosen so that the decoder cannot determine which sensors are traitors while maximizing the required rate to decode every value. Achievability is proved using a scheme in which the decoder receives small packets of information from a sensor until its message can be decoded, before moving on to the next sensor. The sensors use randomization to choose from a set of coding functions, which makes it probabilistically impossible for the traitors to cause the decoder to make an error. Two forms of the fixed-rate problem are considered, one with deterministic coding and one with randomized coding. The achievable rate regions are given for both these problems, and it is shown that lower rates can be achieved with randomized coding.
Iridium‐Catalyzed Regio‐ and Enantioselective Allylic Substitution of Silyl Dienolates Derived from Dioxinones

Reported herein is the iridium-catalyzed regio- and enantioselective allylic substitution reactions of unstabilized silyl dienolates derived from dioxinones. Asymmetric allylic substitution of a variety of allylic trichloroethyl carbonates with these silyl dienolates gave γ-allylated products selectively in 60–84 % yield and 90–98 % ee.
Spaces of change: tribal authorities in the former KaNgwane homeland, South Africa

Author(s): King, Brian H. | Abstract: An underreported consequence of the democratic transition is its impact upon localized governance systems in mediating development opportunities within the former homelands of South Africa. Colonialism and apartheid utilized traditional authorities to control landscapes and people, and while these systems continue to influence the livelihood opportunities available to rural households, their scope and influence are being renegotiated by the emergence of new governance structures. This paper uses a case study from the former KaNgwane homeland to evaluate the role of the Matsamo Tribal Authority in shaping access to land, wood and agricultural projects in the region. It is argued that the colonial and apartheid empowerment of the tribal authorities continues to have symbolic and material meaning within KaNgwane, which shapes the ways that rural households benefit from conservation and development. In the post-apartheid era, newly created democratic structures are challenging traditional governance systems by reworking household access to environmental resources. The intersection between these contrasting, and historically situated, systems suggests a dynamic renegotiation is occurring that will continue to impact rural households within the former places of apartheid.
Multiple instruction issue and single-chip processors

In this paper we evaluate the performance of single-chip processors with multiple functional units. As a basis for our studies we use a processor model that is very similar to many of today's single-chip processors. Using this basic machine model, we investigate the performance that can be achieved if some limited form of multiple instruction issue is supported. For these investigations, we use 4 variants of the basic machine that represented different memory access times and branch execution times. In particular, we evaluate issuing 2 instructions per cycle and find that by restricting multiple instruction issue to load or branch instructions much of the same performance gains can be achieved as in the unrestricted form.
Black-White Differences in Wealth and Asset Composition

Using data from the 1976 and 1978 National Longitudinal Surveys of young men and young women, this study examines racial differences in the magnitude and composition of wealth and the reasons for them. On average, young black families hold 18 percent of the wealth of young white families, and hold their wealth in proportionately different forms. Even after controlling for racial differences in income and other demographic factors, as much as three quarters of the wealth gap remains unexplained. We speculate on the causes for this, concluding that racial differences in intergenerational transfers and to a lesser extent barriers to the accumulation of business and home equity most likely play a role.
Waveform inversion of mantle Love waves:the Born seismogram approach

Normal mode theory, extended to the slightly laterally heterogeneous Earth by the first-order Born approximation, is applied to the waveform inversion of mantle Love waves (200-500 sec) for the Earth's lateral heterogeneity at l=2 and a spherically symmetric anelasticity (Q sub mu) structure. The data are from the Global Digital Seismograph Network (GDSN). The l=2 pattern is very similar to the results of other studies that used either different methods, such as phase velocity measurements and multiplet location measurements, or a different data set, such as mantle Rayleigh waves from different instruments. The results are carefully analyzed for variance reduction and are most naturally explained by heterogeneity in the upper 420 km. Because of the poor resolution of the data set for the deep interior, however, a fairly large heterogeneity in the transition zones, of the order of up to 3.5% in shear wave velocity, is allowed. It is noteworthy that Love waves of this period range can not constrain the structure below 420 km and thus any model presented by similar studies below this depth are likely to be constrained by Rayleigh waves (spheroidal modes) only.
High-valent iron and manganese complexes of corrole and porphyrin in atom transfer and dioxygen evolving catalysis.

Manganese(V) imido complexes of 5,10,15-tris(pentafluorophenyl)corrole (H3tpfc) can be prepared by the reaction of MnIII(tpfc) and organic nitrene generated from either photolytic or thermal activation of organic azides. The terminal imido complexes of manganese(V) were among the first structurally characterized examples of MnV terminal imido complexes in the literature. They feature a short MnN triple bond and a nearly linear MN–C angle. The ground state of (tpfc)MnV(NAr) is singlet. Contrary to expectations, arylimido complexes of manganese(V) were stable to moisture and did not undergo [NR] group transfer to olefins. Manganese(V) imido corrole with an activated tosyl imido ligand was prepared from iodoimine (ArINTs) and manganese(III) corrole. The resulting complex (tpfc)Mn(NTs) is paramagnetic (S = 1), hydrolyzes to (tpfc)Mn(O) in the presence of water, abstracts hydrogen atoms from benzylic C–H bonds, and catalyzes aziridination of alkenes. Mechanistic studies on the aziridination and hydrogen atom transfer reactions are reviewed. This perspective also describes the reaction chemistry of the heme enzyme chlorite dismutase, the mechanism by which dioxygen is formed on a single-metal site, and recent advances in functional modelling of this enzyme. We also compare the reactivity of water-soluble ironversusmanganese porphyrins towards the chlorite anion.
Spaceborne imaging radar-C instrument

The Shuttle Imaging Radar (SIR)-C instrument has been designed to obtain simultaneous multifrequency and simultaneous multipolarization radar images from a low Earth orbit. It is a multiparameter imaging radar that will be flown during two different seasons. The instrument has been designed to operate in innovative modes such as the squint mode, the extended aperture mode, and the scansar mode, and to demonstrate innovative engineering techniques such as beam nulling for echo tracking, pulse repetition frequency-hopping for Doppler centroid tracking, frequency step chirp generating, for polarization differentiation, and block floating-point quantizing for data compression. The instrument has also been designed to allow flexibility in selection of radar parameters such as pulsewidth and beamwidth in the tradeoff of image quality parameters. These SIR-C capabilities are to be directly transferred to the proposed Earth Observing System (Eos) synthetic aperture radar. >
The Matsuno‐Gill Model and Equatorial Superrotation

[1] Equatorial superrotation can be generated in global general circulation models (GCMs) when forced with longitudinally varying heating, similar to that postulated in the Matsuno-Gill model. However, the implications of the classical Matsuno-Gill theory for equatorial superrotation have not, to date, been addressed. Here, we show that the classic, shallow-water Matsuno-Gill solutions do not exhibit equatorial superrotation: although the flow converges westerly momentum from high latitudes to the equator—promoting superrotation—they also contain an artificial source of easterly momentum at the equator that cancels the latitudinal momentum convergence and prevents superrotation from emerging. This artificial momentum source results from a physically inconsistent representation of vertical momentum transport in the model. We show that if the Matsuno-Gill model is modified to properly account for momentum exchange with an underlying quiescent layer, the solutions naturally exhibit equatorial superrotation, at any forcing amplitude.
Large Deviations Asymptotics and the Spectral Theory of Multiplicatively Regular Markov Processes

In this paper we continue the investigation of the spectral theory and exponential asymptotics of primarily discrete-time Markov processes, following Kontoyiannis and Meyn (2003). We introduce a new family of nonlinear Lyapunov drift criteria, which characterize distinct subclasses of geometrically ergodic Markov processes in terms of simple inequalities for the nonlinear generator. We concentrate primarily on the class of multiplicatively regular Markov processes, which are characterized via simple conditions similar to (but weaker than) those of Donsker-Varadhan. For any such process $\{\Phi(t)\}$ with transition kernel $P$ on a general state space $X$, the following are obtained. Spectral Theory: For a large class of (possibly unbounded) functionals $F$ on $X$, the kernel $\hat P(x,dy) = e^{F(x)} P(x,dy)$ has a discrete spectrum in an appropriately defined Banach space. It follows that there exists a "maximal," well-behaved solution to the "multiplicative Poisson equation," defined as an eigenvalue problem for $\hat P$. Multiplicative Mean Ergodic Theorem: Consider the partial sums of this process with respect to any one of the functionals $F$ considered above. The normalized mean of their moment generating function (and not the logarithm of the mean) converges to the above maximal eigenfunction exponentially fast. Multiplicative regularity: The Lyapunov drift criterion under which our results are derived is equivalent to the existence of regeneration times with finite exponential moments for the above partial sums. Large Deviations: The sequence of empirical measures of the process satisfies a large deviations principle in a topology finer that the usual tau-topology, generated by the above class of functionals. The rate function of this LDP is the convex dual of logarithm of the above maximal eigenvalue, and it is shown to coincide with the Donsker-Varadhan rate function in terms of relative entropy. Exact Large Deviations Asymptotics: The above partial sums are shown to satisfy an exact large deviations expansion, analogous to that obtained by Bahadur and Ranga Rao for independent random variables.
Health Monitoring of a Satellite System

A health monitoring system based on analytical redundancy is developed for satellites on elliptical orbits. First, the dynamics of the satellite including orbital mechanics and attitude dynamics is modelled as a periodic system. Then, periodic fault detection filters are designed to detect and identify the satellite's actuator and sensor faults. In addition, parity equations are constructed using the algebraic redundant relationship among the actuators and sensors. Furthermore, a residual processor is designed to generate the probability of each of the actuator and sensor faults by using a sequential probability test. Finally, the health monitoring system, consisting of periodic fault detection lters, parity equations and residual processor, is evaluated in the simulation in the presence of disturbances and uncertainty.
Modeling Unsupervised Perceptual Category Learning

During the learning of speech sounds and other perceptual categories, category labels are not provided, the number of categories is unknown, and the stimuli are encountered sequentially. These constraints provide a challenge for models, but they have been recently addressed in the online mixture estimation model of unsupervised vowel category learning (see Vallabha in the reference section). The model treats categories as Gaussian distributions, proposing both the number and the parameters of the categories. While the model has been shown to successfully learn vowel categories, it has not been evaluated as a model of the learning process. We account for several results: acquired distinctiveness between categories and acquired similarity within categories, a faster increase in discrimination for more acoustically dissimilar vowels, and gradual unsupervised learning of category structure in simple visual stimuli.
Tabu search in audit scheduling

Abstract The problem of audit staff scheduling normally involves auditors with varying efficiencies, and several audit engagements with varying requirements and at different locations. The task of scheduling auditors to the audit tasks becomes more complicated if the scheduler has to accommodate the many real life considerations. The problem, regardless of its size or complexity, has been formulated as a (0–1) integer program. However, the large number of variables and constraints in such a formulation makes the use of exact optimization methods impractical. In this paper, we present a heuristic procedure based on tabu search (TS) and intelligent memory structures for solving this problem. The TS method starts with a feasible schedule generated by a greedy forward dispatching procedure, then through a series of intensification and diversification steps it improves on the initial schedule. The improvement in the value of the objective function is observed interactively. The search can be terminated as the improvement in the value of the objective function stabilizes. Application of the TS method to different audit scheduling problems has led to a consistent and significant improvement in the value of the cost minimization objective function.
Catalytic enantioselective O-H insertion reactions.

The first effective method for catalytic enantioselective insertions into O−H bonds has been developed. Specifically, a copper/bisazaferrocene catalyst couples alcohols such as 2-trimethylsilylethanol with α-aryl-α-diazo esters in high yield and good ee.
Review of Regenerative Adsorption Heat Pumps

NASA is again considering a permanent lunar base as part of its new “Exploration Vision.” Because the lunar surface reaches 100 ◦ C near the equator during the lunar day (14.75 Earth days) and −100 ◦ C during the lunar night (also 14.75 Earth days), some type of heat pump is needed to elevate the temperature of absorbed sunlight and interior waste heat in order to reject it to space. An earlier investigation by M. A. Lambert (“Conceptual Design of a Regenerative Adsorption Heat Pump for a Lunar Base,” AIAA Paper 99-0465, 1999) identified adsorption (solid‐vapor) heat pumps as one of two technologies best suited to this application, the other being a mechanical vapor compression device with a high-efficiency centrifugal compressor. In order to properly preface the creation of a detailed design for an adsorption heat pump, this investigation reviews the state of the art in adsorption heat pumps, specifically the recently developed, much more efficient, regenerative variants. The principal figures of merit are the coefficient of performance for cooling (COPC) and the specific cooling power. Nonregenerative adsorption heat pumps exhibit a COPC of only 0.3 to 0.4, whereas regenerative designs have achieved a COPC of 1.1 with 70% regeneration of waste heat. Attention has focused on maximizing overall heat transfer coefficient and minimizing nonadsorbent mass of the most critical component, the adsorption bed, while maintaining adequate vapor permeability. This involves establishing a thermal wave temperature gradient traversing the bed, which minimizes the temperature difference for heat transfer and entropy generation. A number of novel designs have resulted. The most studied adsorbents are zeolites (a class of highly nanoscopically porous minerals), activated graphite, and silica gel. The refrigerants receiving the greatest attention are ammonia, methanol, and water.
Catalytic Enantioselective Alkylations of Tetrasubstituted Olefins. Synthesis of All-Carbon Quaternary Stereogenic Centers through Cu-Catalyzed Asymmetric Conjugate Additions of Alkylzinc Reagents to Enones

A method for Cu-catalyzed asymmetric conjugate addition (ACA) of dialkylzinc reagents to tetrasubstituted five- and six-membered cyclic enones that afford quaternary all-carbon stereogenic centers in up to 95% ee is reported. Catalytic ACAs are practical and efficient. Reactions proceed to >98% conversion in undistilled commercial grade toluene in the presence of 2 mol % of an air-stable Cu salt (CuCN) and a readily available chiral ligand. Enantioselective ACA reactions deliver products that can be readily functionalized to afford a variety of synthetically versatile compounds in high optical purity.
Influence of Tensioner Dry Friction on the Vibration of Belt Drives With Belt Bending Stiffness

A model of dry friction tensioner in a belt-pulley system considering transverse belt vibration is developed, and the influence of the dry friction on the system dynamics is examined. The discretized formulation is divided into a linear subsystem including linear coordinates and a nonlinear subsystem addressing tensioner arm vibration, which reduces the dimension of the iteration matrices when employing the harmonic balance method. The Coulomb damping at the tensioner arm pivot mitigates the tensioner arm vibration but not necessarily the vibrations of other system components. The extent of the mitigation varies for different excitation frequency ranges. The critical amplitude of the dry friction torque beyond which the system operates with a locked arm is determined analytically. Superharmonic resonances are observed in the responses of the generalized span coordinates, but their amplitudes are small. The energy dissipation at the tensioner arm hub is discussed, and the stick-slip phenomena of the arm are reflected in the velocity reversals near the arm extreme location. Dependence of the span tension fluctuations on Coulomb torque is explored.
PDDL2.1: the art of the possible? commentary on fox and long

PDDL2.1 was designed to push the envelope of what planning algorithms can do, and it has succeeded. It adds two important features: durative actions, which take time (and may have continuous effects); and objective functions for measuring the quality of plans. The concept of durative actions is flawed; and the treatment of their semantics reveals too strong an attachment to the way many contemporary planners work. Future PDDL innovators should focus on producing a clean semantics for additions to the language, and let planner implementers worry about coupling their algorithms to problems expressed in the latest version of the language.