cssi/SciSciGPT-SciSciNet huggingface dataset:
MDS array codes with optimal rebuilding

MDS array codes are widely used in storage systems to protect data against erasures. We address the rebuilding ratio problem, namely, in the case of erasures, what is the the fraction of the remaining information that needs to be accessed in order to rebuild exactly the lost information? It is clear that when the number of erasures equals the maximum number of erasures that an MDS code can correct then the rebuilding ratio is 1 (access all the remaining information). However, the interesting (and more practical) case is when the number of erasures is smaller than the erasure correcting capability of the code. For example, consider an MDS code that can correct two erasures: What is the smallest amount of information that one needs to access in order to correct a single erasure? Previous work showed that the rebuilding ratio is bounded between 1 over 2 and 3 over 4, however, the exact value was left as an open problem. In this paper, we solve this open problem and prove that for the case of a single erasure with a 2-erasure correcting code, the rebuilding ratio is 1 over 2. In general, we construct a new family of r-erasure correcting MDS array codes that has optimal rebuilding ratio of 1 over r in the case of a single erasure. Our array codes have efficient encoding and decoding algorithms (for the case r = 2 they use a finite field of size 3) and an optimal update property.
Use of production systems for modeling asynchronous, concurrent processes

Because of the event-driven, nature of asynchronous, concurrent processes, production systems (PS's) are an attractive modeling tool. The system of interest can be modeled with a large number of independent states, with independent actions, and tile knowledge base can be conveniently encoded declaratively. However, asynchronous, concurrent processes normally have strict requirements for inter-process communication and coordination; this requires a substantial degree of inter-rule communication in the PS. The result of this is that a complex control structure is embedded in the short term memory (STM); this is generally considered unattractive for a number of reasons. This paper proposes a separate, explicit control structure for modeling asynchronous, concurrent processes With PS's. Specifically, the use of a Petri net is addressed. A system of asynchronous, concurrent processes can be modeled using 'PS's to model the individual processes or events and using a Petri net to model the relationships between the processes. Furthermore, a hierarchy of such networks is proposed; an allowable production rule action is the instantiation of another network. This is supported with a structured, hierarchial STM.
SYNTHESIS OF PURPURATE-1,1′-DIACETIC ACID (PDAA) TRIPOTASSIUM SALT. A NEW CALCIUM INDICATOR FOR BIOLOGICAL APPLICATIONS

(1989). SYNTHESIS OF PURPURATE-1,1′-DIACETIC ACID (PDAA) TRIPOTASSIUM SALT. A NEW CALCIUM INDICATOR FOR BIOLOGICAL APPLICATIONS. Organic Preparations and Procedures International: Vol. 21, No. 4, pp. 493-500.
Trade and trade finance developments in 14 developing countries post September 2008 - a World Bank survey

In the aftermath of the Lehman Brothers collapse in September 2008, drop in the supply of trade finance, a critical engine for trade transactions, has become an acute concern for the development community. Banks were increasing pricing on trade finance transactions to cover increased funding costs and higher credit risks, and trade was dropping drastically in most countries, with global trade projected to decline in 2009 for the first time in decades. Yet, little was known about the real impact of the crisis on developing countrys capacity to export. The World Bank has commissioned a firm and bank survey on trade and trade finance developments in developing countries during the first quarter of 2009 to collect field information. In total, 425 firms and 78 banks were surveyed in 14 developing countries across five regions. This paper summarizes the findings of the survey as well as discusses the type of policies governments and international organizations put in place to mitigate the impact of the crisis. In sum, the survey findings confirmed that the global financial crisis has constrained trade finance for exporters and importers in developing countries. But the impact varied by the firm size, sectoral activity, and countries integration into the global economy. In particular, SMEs were particularly affected, and export diversification was made more difficult, especially in low income countries. Nevertheless, drop in demand has emerged as the top concern of firms at the time when the survey was conducted in March-April 2009.
R Centauri: An Unusual Mira Variable in a He-Shell Flash

We present an analysis of AAVSO visual observations of the Mira variable R Cen from 1918 to 2000. The period of the dominant mode has been steadily decreasing from 550 days at JD 2,434,000 (1951) to its present value of 505-510 days. In the same interval, the pulsational amplitude has decreased by 3 mag, from 5.5-11.8 V to 6.3-9.1 V. We suggest that both are caused by a He-shell flash, as the period decrease is similar to that of other He-shell flash stars such as R Hya, R Aql, and T UMi. The period change is consistent with the luminosity drop expected immediately after the flash, as predicted by He-shell flash models for stars of 2-3 M, or less. The light curve shows the familiar pattern of alternating deep and shallow minima, giving the appearance of double maxima. While the amplitude of the main mode has decreased 3 mag in the last 50 years, the amplitude of the secondary mode near 274 days has remained almost constant, so that the double maxima have nearly vanished from the light curve in recent years. The power spectrum between 1930 and 1966 shows harmonics up to 8 times the main frequency at 1/548 cycle day 1 . The most likely explanation for the double-peaked light curve is a resonance between two modes.
Task reweighting under global scheduling on multiprocessors

We consider schemes for enacting task share changes--a process called reweighting--on real-time multiprocessor platforms. Our particular focus is reweighting schemes that are deployed in environments in which tasks may frequently request significant share changes. Prior work has shown that fair scheduling algorithms are capable of reweighting tasks with minimal allocation error and that partitioning-based scheduling algorithms can reweight tasks with better average-case performance, but greater error. However, preemption and migration overheads can be high in fair schemes. In this paper, we consider the question of whether non-fair, earliest-deadline-first ( $\mathsf{EDF}$ ) global scheduling techniques can improve the accuracy of reweighting relative to partitioning-based schemes and provide improved average-case performance relative to fair-scheduled systems. Our conclusion is that, for soft real-time systems, global $\mathsf{EDF}$ schemes provide a good mix of accuracy and average-case performance.
A 1.5-V, 1.5-GHz CMOS low noise amplifier

A 1.5-GHz low noise amplifier (LNA), intended for use in a global positioning system (GPS) receiver, has been implemented in a standard 0.6-/spl mu/m CMOS process. The amplifier provides a forward gain (S21) of 22 dB with a noise figure of only 3.5 dB while drawing 30 mW from a 1.5 V supply. In this paper, we present a detailed analysis of the LNA architecture, including a discussion on the effects of induced gate noise in MOS devices.
Competition for Land in the Global Bioeconomy

The global land use implications of biofuel expansion have received considerable attention in the literature over the past decade. Model-based estimates of the emissions from cropland expansion have been used to assess the environmental impacts of biofuel policies. And integrated assessment models have estimated the potential for biofuels to contribute to greenhouse gas (GHG) abatement over the coming century. All of these studies feature, explicitly or implicitly, competition between biofuel feed stocks and other land uses. However, the economic mechanisms governing this competition, as well as the contribution of biofuels to global land use change, have not received the close scrutiny that they deserve. The purpose of this article is to offer a deeper look at these factors. We begin with a comparative static analysis which assesses the impact of exogenously specified forecasts of biofuel expansion over the period: 2006–2035. Global land use change is decomposed according to the three key margins of economic response: extensive supply, intensive supply, and demand. Under the International Energy Agency’s “New Policies” scenario, biofuels account for nearly one-fifth of global land use change over the 2006–2035 period. The article also offers a comparative dynamic analysis which determines the optimal path for first and second generation biofuels over the course of the entire 21st century. In the absence of GHG regulation, the welfare-maximizing path for global land use, in the face of 3% annual growth in oil prices, allocates 225 Mha to biofuel feed stocks by 2100, with the associated biofuels accounting for about 30% of global liquid fuel consumption. This area expansion is somewhat diminished by expected climate change impacts on agriculture, while it is significantly increased by an aggressive GHG emissions target and by advances in conversion efficiency of second generation biofuels. JEL classifications: Q11, Q15, Q24, Q42, Q54
Tandem reactions, cascade sequences, and biomimetic strategies in total synthesis

Cascade reactions and biomimetic strategies are being increasingly applied to the construction of natural and designed molecules. Such processes, in which ideally a single event triggers the conversion of a starting material to a product which then becomes a substrate for the next reaction until termination leads to a stable final product, are highly desirable not only due to their elegance, but also because of their efficiency and economy in terms of reagent consumption and purification. Often, these multistep, one-pot procedures are accompanied by dramatic increases in molecular complexity and impressive selectivity. The discovery of new molecular diversity from Nature and the demand for more efficient and environmentally benign chemical processes dictates and invites the further development of such synthetic strategies and tactics as we move into a new age of chemical synthesis. Within this article, a number of instructive examples of such synthetic strategies from the principal author's laboratories are discussed.
Theory of a traveling wave feed for a planar slot array antenna

A planar array of longitudinal radiating slots cut in broad walls of rectangular waveguides is fed by a traveling wave array of centered-inclined coupling slots cut in the common broad walls of a feed waveguide and an array of orthogonal radiating waveguides. A theory is developed for the design of the resonant coupling slots using the scattering matrix representation. Numerical results computed for the radiation pattern, the tilt angles of coupling slots, and excitation phases of the radiating waveguides are presented for a uniformly excited array. It is shown that the use of resonant coupling slots simplifies the design process.
Efficient evaluation of radial queries using the target tree

We propose a novel indexing structure, called the target tree, which is designed to answer a new type of spatial query, called the radial query. A radial query finds all objects in the spatial data set that intersect with line segments emanating from a single target point. Many biomedical applications use radial queries, including neurosurgical planning. A target tree uses a regular hierarchical decomposition of space using wedge shapes that emanate from the target point. We compare the target tree with the R*-tree and quadtree, and show that the target tree is significantly faster than these methods.
Differential recursion relations for Laguerre functions on symmetric cones

Let be a symmetric cone and V the corresponding simple Euclidean Jor- dan algebra. In (2, 5, 6, 8) we considered the family of generalized Laguerre functions on that generalize the classical Laguerre functions on R + . This family forms an orthogo- nal basis for the subspace of L-invariant functions in L 2 (,dµ�), where dµ� is a certain measure on the cone and where L is the group of linear transformations on V that leave the cone invariant and fix the identity in . The space L 2 (,dµ�) supports a highest weight representation of the group G of holomorphic diffeomorphisms that act on the tube domain T() = + iV. In this article we give an explicit formula for the action of the Lie algebra of G and via this action determine second order differential operators which give differential recursion relations for the generalized Laguerre functions gener- alizing the classical creation, preservation, and annihilation relations for the Laguerre functions on R + .
Rain Effects at Low Reynolds Number

Wind-tunnel tests were conducted to determine the influence of rain on the aerodynamic performance of the Wortmann FX63-137 wing at Reynolds numbers 100,000-300,000. Models with aspect ratios of 6 and 4 were tested with normal as well as waxed and soaped surfaces to evaluate wettability effects. Test results showed an improvement of performance at the lowest Reynolds number but general deterioration at higher speeds. The primary effect noted was a decrease in lift at higher angles of attack. A favorable result was the elimination of stall hysteresis, which characterizes the Wortmann's normal performance at low Reynolds numbers. At lower Reynolds numbers, rain appeared to lower drag whereas, at higher speeds, drag generally increased.
Robust stabilization and robust performance using model reference control and modeling error compensation

A new robust linear controller design method is considered. The robust controller consists of two parts: 1) a conventional model matching feedback and 2) a new linear "modeling error compensator" which exploits a modeling error signal (based on the plant input and output signals) to enhance both the stability and performance robustness. For linear SISO systems of known order without right half plane zeros and arbitrary variation of transfer function coefficients within a given bounded set, a modeling error compensator can be designed which guarantees robust stability and an arbitrary small H/sub /spl infin//-norm of the tracking error transfer function over a given frequency band. Examples show that modeling error compensation can also be used to improve the robustness for systems with right half plane zeros, and that the transient response using model error compensation is better than that using model reference adaptive control. >
Public sectors in the pacific islands : are they 'too big' and do they 'crowd out' the private sector ?

Public sectors in the Pacific Islands are frequently described as being 'too big' and as 'crowding out' private sector economic activity. Reducing their size, it follows, would provide much-needed space for private sector expansion and result in higher levels of economic growth. This paper addresses these issues, arguing that there is not a good case for supposing that public sectors in the Pacific Islands are excessively large, when the challenges of public administration and public service delivery in such small, remote, dispersed, and divided states are taken into account. Rather than being preoccupied with their size, it would be more useful to focus on whether the resources available to their public sectors are being used efficiently and effectively to provide an adequate range and quality of administrative functions and public services. The paper also argues that, at a general level, the case for crowding out in the Pacific Islands is not particularly compelling, and that it would be more useful to focus on the trade-offs for the private sector of public sector engagement in any given administrative function or area of service delivery. In light of the arguments put forward, the paper sets out the key elements of a refocused agenda on public sector reform in the Pacific Islands.
Terpene Biosynthesis: Modularity Rules

Terpenes are the largest class of small-molecule natural products on earth, and the most abundant by mass. Here, we summarize recent developments in elucidating the structure and function of the proteins involved in their biosynthesis. There are six main building blocks or modules (α, β, γ, δ, e, and ζ) that make up the structures of these enzymes: the αα and αδ head-to-tail trans-prenyl transferases that produce trans-isoprenoid diphosphates from C(5) precursors; the e head-to-head prenyl transferases that convert these diphosphates into the tri- and tetraterpene precursors of sterols, hopanoids, and carotenoids; the βγ di- and triterpene synthases; the ζ head-to-tail cis-prenyl transferases that produce the cis-isoprenoid diphosphates involved in bacterial cell wall biosynthesis; and finally the α, αβ, and αβγ terpene synthases that produce plant terpenes, with many of these modular enzymes having originated from ancestral α and β domain proteins. We also review progress in determining the structure and function of the two 4Fe-4S reductases involved in formation of the C(5) diphosphates in many bacteria, where again, highly modular structures are found.
Towards an Integrated Global Agricultural Greenhouse Gas Model: Greenhouse Gases from Agriculture Simulation Model (GreenAgSiM)

The Greenhouse Gases from Agriculture Simulation Model (GreenAgSiM) presented in this paper aims to quantify emissions from agricultural activity on a global scale. The model takes emissions into account that are directly attributable to agricultural production, such as enteric fermentation (methane), manure management (methane and nitrous oxide), and agricultural soil management (nitrous oxide). Furthermore, carbon stock differences from land-use change (carbon dioxide) induced by agriculture are included in the model. The model will provide policy makers with information about the greenhouse gas implications of policy changes.
Detection of Magnetic Massive Stars in the Open Cluster NGC 3766

A growing number of observations indicate that magnetic fields are present among a small fraction of massive O- and B-type stars, yet the origin of these fields remains unclear. Here we present the results of a VLT/FORS1 spectropolarimetric survey of 15 B-type members of the open cluster NGC 3766. We have detected two magnetic B stars in the cluster, including one with a large field of nearly 2 kG, and we find marginal detections of two additional stars. There is no correlation between the observed longitudinal field strengths and the projected rotational velocity, suggesting that a dynamo origin for the fields is unlikely. We also use the oblique dipole rotator model to simulate populations of magnetic stars with uniform or slightly varying magnetic flux on the ZAMS. None of the models successfully reproduces our observed range in Bl and the expected number of field detections, and we rule out a purely fossil origin for the observed fields.
Throughput-optimal opportunistic scheduling in the presence of flow-level dynamics

We consider multiuser scheduling in wireless networks with channel variations and flow-level dynamics. Recently, it has been shown that the MaxWeight algorithm, which is throughput-optimal in networks with a fixed number of users, fails to achieve the maximum throughput in the presence of flow-level dynamics. In this paper, we propose a new algorithm, called Workload-based Scheduling with Learning, which is provably throughput-optimal, requires no prior knowledge of channels and user demands, and performs significantly better than previously suggested algorithms.
Efficient and stereoselective cross-coupling with highly substituted alkenylsilanols

Highly substituted alkenylsilanols (1), readily prepared from commercially available simple starting materials, are efficiently coupled with aryl or alkenyl halides in the presence of tetrabutylammonium fluoride (TBAF) and a palladium(0) catalyst. Yields are generally high and the reactions are highly stereoselective and compatible with a wide range of functional groups.
Endoscopic management of pediatric nasolacrimal anomalies

Developmental anomalies of the nasolacrimal drainage system typically manifest early in childhood. Although the majority of cases of congenital nasolacrimal obstruction resolve spontaneously with conservative management, certain anomalies like dacryocystoceles require operative intervention. In children with persistent nasolacrimal obstruction, endoscopic dacryocystorhinostomy (DCR) provides an equally efficacious alternative to external DCR that concurrently allows for the potential correction of any predisposing intranasal pathology. Endoscopic DCR is best performed as a joint otolaryngologic–ophthalmologic procedure.
Warped spectroscopy: localization of frozen bulk modes

We study the 10D equation of motion of dilaton-axion fluctuations in type IIB string compactifications with three-form flux, taking warping into account. Using simplified models with physics comparable to actual compactifications, we argue that the lightest mode localizes in long warped throats and takes a mass of order the warped string scale. Also, the Gukov-Vafa-Witten superpotential is valid for the lightest mass mode; however, the mass is similar to the Kaluza-Klein scale, so the dilaton-axion should be integrated out of the effective theory in this long throat regime (leaving a constant superpotential). On the other hand, there is a large hierarchy between flux-induced and KK mass scales for moderate or weak warping. This hierarchy agrees with arguments given for trivial warping. Along the way, we also estimate the effect of the other 10D supergravity equations of motion on the dilaton-axion fluctuation, since these equations act as constraints. We argue that they give negligible corrections to the simplest approximation.
Approximation of frequency responses based on Larsson's method

This paper discusses the new aspects of the formulation for structural model updates presented by Larsson and Sas at the 10th International Modal Analysis Conference held in San Diego, California in February 1991. First, a closed-form representation of the reduced impedance matrix is presented. It clarifies the issues associated with the range of the excitation frequencies used in model updates. Second, the applicable range of excitation frequencies is considered through an example where low frequency local modes are present. Third, the computational aspects of this algorithm are studied. It is shown that displacement sensitivity vectors corresponding to the virtual loads are critical in the computation of the reduced impedance matrix sensitivity. Finally, applicability of this algorithm for approximate frequency responses in structural optimization is studied. Numerical results are included to illustrate the essence of this formulation.
Assessment and Diagnosis of Personality Disorder: Perennial Issues and an Emerging Reconceptualization

AbstractThis chapter reviews recent (2000–2005) personality disorder (PD) research, focusing on three major domains: assessment, comorbidity, and stability. (a) Substantial evidence has accrued favoring dimensional over categorical conceptualization of PD, and the five-factor model of personality is prominent as an integrating framework. Future directions include assessing dysfunction separately from traits and learning to utilize collateral information. (b) To address the pervasiveness and extent of comorbidity, researchers have begun to move beyond studying overlapping pairs or small sets of disorders and are developing broader, more integrated common-factor models that cross the Axis I–Axis II boundary. (c) Studies of PD stability have converged on the finding that PD features include both more acute, dysfunctional behaviors that resolve in relatively short periods, and maladaptive temperamental traits that are relatively more stable—similar to normal-range personality traits—with increasing stability ...
Pseudospin order in monolayer, bilayer and double-layer graphene

Graphene is a gapless semiconductor in which conduction and valence band wavefunctions differ only in the phase difference between their projections onto the two sublattices of the material's two-dimensional honeycomb crystal structure. We explain why this circumstance creates openings for broken symmetry states, including antiferromagnetic states in monolayer and bilayer graphene and exciton condensates in double-layer graphene, which are momentum space analogues of the real-space order common in systems with strong local interactions. We discuss some similarities among, and some differences between, these three broken symmetry states.
Versatile reactivity of Pd-catalysts: mechanistic features of the mono-N-protected amino acid ligand and cesium-halide base in Pd-catalyzed C-H bond functionalization.

The widely used C–H functionalization strategies and some complexities in the Pd-catalyzed chemical transformations were analyzed. It was emphasized that in the course of catalysis various Pd-intermediates (including nano-scale Pd-clusters) could act as active catalysts. However, both identification of these catalytically active species and determination of factors controlling the overall catalytic process require more comprehensive and multi-disciplinary approaches. Recent joint computational and experimental approaches were instrumental in: (1) demonstrating that the addition of Pd(OAc)2 as a catalyst precursor to RSeH and RSH reagents forms the [Pd(SeR)2]n and [Pd(SR)2]n clusters, respectively, which show an unprecedented ability for selective synthesis of Markovnikov-type products starting with a mixture of reagents RSH/RSeH and acetylenic hydrocarbons; (2) predicting a valid mechanism of the amino acid ligand-assisted Pd(II)-catalyzed C–H activation that is shown to proceed via the formation of the catalytically active Pd(II) intermediate with a bidentately coordinated dianionic amino acid ligand; (3) demonstrating that the amino acid ligand plays crucial roles in the ligand-assisted Pd(II)-catalyzed C–H activation by acting as: (a) a weakly coordinating ligand to stabilize the desirable Pd(II)-precatalyst, (b) a soft proton donor and a bidentately coordinated dianionic ligand in the catalytically active Pd(II) intermediate, and (c) a proton acceptor accelerating the C–H deprotonation via the CMD mechanism; and (4) revealing the roles of the CsF base (and “cesium effect”) in the Pd(0)/PCy3-catalyzed intermolecular arylation of the terminal β-C(sp3)–H bond of aryl amide and predicting the unprecedented “Cs2-I-F cluster” assisted mechanism for this reaction.
Non-local corrections to the electronic structure of metal surfaces

Abstract A non-local exchange-correlation term, derived from the static dielectric function of Vashishta and Singwi (VS), is introduced into the density functional for an interacting electron gas. The coefficient is chosen to give the same surface energy for two adjacent jellium metals of nearly equal density as is obtained from the VS dielectric function. This density functional is then used to calculate surface energies and work functions for metal-vacuum interfaces. The results for both surface energies and work functions found in this way are significantly higher than the experimental values. Possible explanations for the discrepancies are discussed.
Structural Response of Compression-Loaded, Tow-Placed, Variable Stiffness Panels

Results of an analytical and experimental study to characterize the structural response of two compression-loaded variable stiffness composite panels are presented and discussed. These variable stiffness panels are advanced composite structures, in which tows are laid down along precise curvilinear paths within each ply and the fiber orientation angle varies continuously throughout each ply. The panels are manufactured from AS4/977-3 graphite-epoxy pre-preg material using an advanced tow placement system. Both variable stiffness panels have the same layup, but one panel has overlapping tow bands and the other panel has a constant-thickness laminate. A baseline cross-ply panel is also analyzed and tested for comparative purposes. Tests performed on the variable stiffness panels show a linear prebuckling load-deflection response, followed by a nonlinear response to failure at loads between 4 and 53 percent greater than the baseline panel failure load. The structural response of the variable stiffness panels is also evaluated using finite element analyses. Nonlinear analyses of the variable stiffness panels are performed which include mechanical and thermal prestresses. Results from analyses that include thermal prestress conditions correlate well with measured variable stiffness panel results. The predicted response of the baseline panel also correlates well with measured results.
Chemical self-assembly of graphene sheets

Chemically derived and noncovalently functionalized graphene sheets (GS) were found to self-assemble onto patterned gold structures via electrostatic interactions between the functional groups and the gold surfaces. This afforded regular arrays of single graphene sheets on large substrates, which were characterized by scanning electron microscopy (SEM), Auger microscopy imaging, and Raman spectroscopy. This represents the first time that self-assembly has been used to produce on-substrate and fully-suspended graphene electrical devices. Molecular coatings on the GS were removed by high current “electrical annealing”, which restored the high electrical conductance and Dirac point of the GS. Molecular sensors for highly sensitive gas detection using the self-assembled GS devices are demonstrated.
The Entourage Effect

Across a series of studies conducted in both the field and the laboratory, the authors demonstrate that the presence of others (i.e., an entourage) alters a VIP's personal feelings of status. Specifically, the authors show that VIPs feel higher levels of status when they are able to experience preferential treatment with an entourage, even if this results in the rewards associated with the treatment becoming less scarce. We show that the effect is driven by an increase in feelings of connection with one's guests. Several alternative explanations for the entourage effect are ruled out, and implications for practice are discussed.
Grain size in the lower mantle: constraints from numerical modeling of grain growth in two-phase systems

Abstract The lower mantle is believed to deform in the grain size-sensitive creep regime. Analysis of physical processes in the convective mantle suggests that the grain size is probably very small immediately after the phase transformations at 660 km depth and is controlled by subsequent grain growth. It was proposed that the microstructural evolution of two-phase aggregates eventually reaches an asymptotic regime in which grain growth in both phases is coupled due to Zener pinning and obeys a power-law scaling relationship d ∝ t 1/ n . We performed Monte Carlo simulations for a particular case in which grain growth is controlled by diffusion along grain boundaries ( n =4) and found a good agreement with theoretical predictions. On geological time scales the grain size of (Mg, Fe)-perovskite is controlled by Ostwald ripening of magnesiowustite and Ca-perovskite. However, the physical parameters are poorly constrained and the grain size remains highly uncertain. If the rate-limiting process is silicon diffusion, the coarsening exponent is likely to be n =3 and the grain size is likely to be 100–1000 μm.
Constant Rate Distributions on Partially Ordered Sets

We consider probability distributions with constant rate on partially ordered sets, generalizing distributions in the usual reliability setting ([0,∞),≤) that have constant failure rate. In spite of the minimal algebraic structure, there is a surprisingly rich theory, including moment results and results concerning ladder variables and point processes. We concentrate mostly on discrete posets, particularly posets whose graphs are rooted trees. We pose some questions on the existence of constant rate distributions for general discrete posets.
The dichotomy of conjunctive queries on probabilistic structures

We show that for every conjunctive query, the complexity of evaluating it on a probabilistic database is either PTIME or P-complete, and we give an algorithm for deciding whether a given conjunctive query is PTIME or P-complete. The dichotomy property is a fundamental result on query evaluation on probabilistic databases and it gives a complete classification of the complexity of conjunctive queries.
Grid orthogonality effects on predicted turbine midspan heat transfer and performance

The effect of five different C type grid geometries on the predicted heat transfer and aerodynamic performance of a turbine stator is examined. Predictions were obtained using two flow analysis codes. One was a finite difference analysis, and the other was a finite volume analysis. Differences among the grids in terms of heat transfer and overall performance were small. The most significant difference among the five grids occurred in the prediction of pitchwise variation in total pressure. There was consistency between results obtained with each of the flow analysis codes when the same grid was used. A grid generating procedure in which the viscous grid is embedded within an inviscid type grid resulted in the best overall performance.
The Aggregation and Fibrillation of α-Synuclein

α-Synuclein is a small (14 kDa), abundant, intrinsically disordered presynaptic protein, whose aggregation is believed to be a critical step in Parkinson's disease (PD). The kinetics of α-synuclein fibrillation are consistent with a nucleation-dependent mechanism, in which the critical early stage of the structural transformation involves a partially folded intermediate. Although the basis for the toxic effects of aggregated α-synuclein are unknown, it has been proposed that transient oligomers are responsible, possibly by forming pores in membranes. In this Account, I discuss our investigations into the molecular basis for α-synuclein aggregation/fibrillation, including factors that either accelerate or inhibit fibrillation, effects of molecular crowding, oxidation, point mutations, and lipid membranes, as well as the variety of conformational and oligomeric states that α-synuclein can adopt. It is apparent that neuronal cells must have a very fine balance of factors that control the levels and potential...
Thermal perturbations caused by large impacts and consequences for mantle convection

United States. National Aeronautics and Space Administration. Planetary Geology and Geophysics Program
Strategic Extremism: Why Republicans and Democrats Divide on Religious Values

Party platforms differ sharply from one another, especially on issues with religious content, such as abortion or gay marriage. Given the high return to attracting the median voter, why do vote-maximizing politicians take extreme positions? In this paper we find that strategic extremism depends on an intensive margin where politicians want to induce their core constituents to vote (or make donations) and the ability to target political messages toward those core constituents. Our model predicts that the political relevance of religious issues is highest when around one-half of the voting population attends church regularly. Using data from across the world and within the United States, we indeed find a nonmonotonic relationship between religious extremism and religious attendance.
Do Motor-Vehicle Users in the US Pay Their Way?

Governments in the US spend over a hundred billion dollars per year to build and maintain roads and provide a variety of services for motor-vehicle users. To pay for these infrastructure and services governments collect revenue from a variety of taxes and fees. The basic objective of this paper is to compare these government expenditures with the corresponding user tax and fee payments in the US. At the outset I argue that the such comparisons tell us something about the equity but not necessarily the economic efficiency of highway financing. I then present four
Metric aspects of noncommutative homogeneous spaces

For a closed cocompact subgroup Γ of a locally compact group G, given a compact abelian subgroup K of G and a homomorphism ρ:Kˆ→G satisfying certain conditions, Landstad and Raeburn constructed equivariant noncommutative deformations C∗(Gˆ/Γ,ρ) of the homogeneous space G/Γ, generalizing Rieffel's construction of quantum Heisenberg manifolds. We show that when G is a Lie group and G/Γ is connected, given any norm on the Lie algebra of G, the seminorm on C∗(Gˆ/Γ,ρ) induced by the derivation map of the canonical G-action defines a compact quantum metric. Furthermore, it is shown that this compact quantum metric space depends on ρ continuously, with respect to quantum Gromov–Hausdorff distances.
Geometric tracking control of the attitude dynamics of a rigid body on SO(3)

This paper provides new results for a tracking control of the attitude dynamics of a rigid body. Both of the attitude dynamics and the proposed control system are globally expressed on the special orthogonal group, to avoid complexities and ambiguities associated with other attitude representations such as Euler angles or quaternions. By selecting an attitude error function carefully, we show that the proposed control system guarantees a desirable tracking performance uniformly for nontrivial rotational maneuvers involving a large initial attitude error. In a special case where the desired attitude command is fixed, we also show that the attitude dynamics can be stabilized without the knowledge of an inertia matrix. These are illustrated by numerical examples.
Implications of maneuvering-range constraints on lifting-vehicle design.

Abstract : The effects of decreases in the maneuvering range angle on the design parameters for a lifting maneuverable spacecraft performing orbital plane changes aerodynamically are investigated. The design parameters considered here are the velocity or propulsion requirements, the heat transfer, accelerations, and total time of flight for the maneuver. The results indicate that these parameters become more critical as the maneuvering range decreases. Specified limits on these design parameters and constraints on the maneuvering range can be superimposed graphically on a single chart, thus defining an allowable maneuvering region. The high heating rates resulting from small-range-angle maneuvers severely restrict the extent of the maneuverability envelope. In order to extend the maneuvering capabilities for small range angles, the vehicle must be designed for high propellent capacity, high g-loading, and sophisticated heat-protection systems. (Author)
Structure and symmetry in coherent perfect polarization rotation

Theoretical investigations of different routes to coherent perfect polarization rotation illustrate its phenomenological connection with coherent perfect absorption. Our study of systems with broken parity, layering, combined Faraday rotation and optical activity, or a rotator-loaded optical cavity highlights their similarity and suggests alternate approaches to improving and miniaturizing optical devices.
Bisimilar control affine systems

The notion of bisimulation plays a very important role in theoretical computer science where it provides several notions of equivalence between models of computation. These equivalences are in turn used to simplify verification and synthesis for these models as well as to enable compositional reasoning. In systems theory, a similar notion is also of interest in order to develop modular verification and design tools for purely continuous or hybrid control systems. In this paper, we introduce two notions of bisimulation for nonlinear systems. We present differential geometric characterizations of these notions and show that bisimilar systems of different dimensions are obtained by factoring out certain invariant distributions. Furthermore, we also show that all bisimilar systems of different dimension are of this form.
TCP-Aware Backpressure Routing and Scheduling

In this work, we explore the performance of backpressure routing and scheduling for TCP flows over wireless networks. TCP and backpressure are not compatible due to a mismatch between the congestion control mechanism of TCP and the queue size based routing and scheduling of the backpressure framework. We propose a TCP-aware backpressure routing and scheduling mechanism that takes into account the behavior of TCP flows. TCP-aware backpressure provides throughput optimality guarantees in the Lyapunov optimization framework, and gracefully combines TCP and backpressure without making any changes to the TCP protocol. The simulation results show that TCP-aware backpressure (i) improves the throughput of TCP flows significantly, (ii) provides fairness across competing TCP flows, and (iii) accommodates both TCP and non-TCP flows in a wireless network, and improves throughput of these flows without hurting fairness.
Acoustic nonlinearities and power losses at orifices

Acoustic power losses occur when high-amplitude sound waves impinge on an orifice in the absence of mean flow. Described is a simple theoretical model of these losses, in which a harmonic, linear acoustic field is coupled to a nonlinear hydrodynamic flowfield at the orifice. Experimental and theoretical data on power losses at orifices with both pc and flanged acoustic terminations are compared, and fairly good agreement is noted. The structure of the flowfield in the neighborhood of the orifice is broadly described and some quantitative comparisons are made between the measured translational velocity of the ring vortices shed from both sides of the orifice and theoretical predictions. Again, the theory is seen to give generally reasonable results.