cssi/SciSciGPT-SciSciNet huggingface dataset:
Checking the correctness of memories

We extend the notion of program checking to include programs which alter their environment. In particular, we consider programs which store and retrieve data from memory. The model we consider allows the checker a small amount of reliable memory. The checker is presented with a sequence of requests (on-line) to a data structure which must reside in a large but unreliable memory. We view the data structure as being controlled by an adversary. We want the checker to perform each operation in the input sequence using its reliable memory and the unreliable data structure so that any error in the operation of the structure will be detected by the checker with high probability. We present checkers for various data structures. We prove lower bounds of logn on the amount of reliable memory needed by these checkers wheren is the size of the structure. The lower bounds are information theoretic and apply under various assumptions. We also show time-space tradeoffs for checking random access memories as a generalization of those for coherent functions.
Scale Economies in Union Pension Plan Administration: 1981–1993

We confirm previous findings that as the pension plan size increases, administrative costs per participant and asset fall after controlling for the proportion of retirees in a plan. However, we question the inference that the high costs of administering small plans partly explains why small firms generally do not sponsor pension plans. This study uses Internal Revenue Service annual data to compare the administrative costs of Taft-Hartley plans from 1981 to 1993. Centralization may save costs but also may inhibit formation. Union plans are naturally small; they form at the local level.
Phase Transformation in Silica-Coated FePt Nanoparticles

Chemically synthesized FePt nanoparticles (NPs), with an average size of 5.8 nm, were coated with silica (SiO2) shells. The thickness of the silica shell could be controlled between 7.5-25 nm. A modified heating profile has been adopted with which silica shell cracking at high temperatures (1000degC) could be prevented. Even with prolonged heating for 24 h at 800degC, no sintering of the particles is observed. Low temperature (7 K) and room temperature magnetization scans show low coercivity values which are possibly due to a compositional distribution among the individual NPs.
Decaying Cold Dark Matter Model and Small-Scale Power

The canonical cosmological constant-dominated cold dark matter model (ΛCDM) may possess too much power on small scales at z = 0, manifested as central overconcentration of dark matter and overabundance of dwarf galaxies. We suggest an alternative model, ΛDCDM, where one-half of the cold dark matter particles decay into relativistic particles by z = 0. The model successfully lowers the concentration of dark matter in dwarf galaxies as well as in large galaxies like our own at low redshift while simultaneously retaining the virtues of the ΛCDM model. The model solves the problem of overproduction of small dwarf galaxies in the ΛCDM, not by removing them but by identifying them with failed, "dark" galaxies, where star formation is quenched as a result of dark matter evaporation and consequent halo expansion. A dramatic difference between the ΛDCDM model and other proposed variants of the ΛCDM model is that the small-scale power at high redshift (z > 2) in the ΛDCDM model is enhanced compared to the ΛCDM model. A COBE- and cluster-normalized ΛDCDM model can be constructed with the following parameters: H0 = 60 km s-1 Mpc-1, λ0 = 0.60, Ω0, CDM = 0.234, Ω0, b = 0.044, n = 1.0, and σ8 = 1.06. A clean test of this model can be made by measuring the evolution of the gas fraction in clusters. The prediction is that the gas fraction should decrease with redshift and is smaller by 31% at z = 1 than at z = 0. X-ray and Sunyaev-Zeldovich effect observations should provide such a test.
Microstructure in Hydrated Silicate Glasses

A microstructure ranging from 5 to 20 nm in size was detected by small-angle X-ray scattering in Na2O·3SiO2 and 4EaO·28Na2O·68SiO2 glasses hydrated at ∼100° and 80°C, respectively. This observation suggests the presence of silica gel-solvent (water) phase separation.
Field analysis of a dielectric-loaded rectangular waveguide accelerating structure.

Recently, there has been some interest in planar or rectangular dielectric accelerating structures for future high-gradient linear accelerators. In this paper, we present a detailed analysis of the modes of a dielectric-loaded rectangular waveguide accelerating structure based on a circuit model approximation and mode matching method. In general, the acceleration field in a synchronous acceleration mode is nonuniform in the two transverse dimensions. We show, however, that by using a series of rectangular structures successively rotated by 90\ifmmode^\circ\else\textdegree\fi{}, the net accelerating force can be made almost uniform. Characteristic parameters such as $R/Q,$ group velocity, and attenuation constant for X- and W-band accelerators are calculated. The longitudinal wakefields experienced by a relativistic charged particle beam in these structures are also presented. These analytical results are also compared with numerical calculations using the MAFIA code suite demonstrating the validity of our analytic approach.
Laser-induced fluorescence line narrowing in atomic vapors

The use of highly monochromatic light permits the selective excitation of atoms in vapors if excitation and detection of the fluorescence is carried out collinearly. The atoms capable of absorbing light then form an atomic beam of well-defined velocity along the direction of the laser beam, but no velocity selection occurs perpendicular to it. The potential of the technique for Doppler-free atomic spectroscopy and for the study of excited atom collisions is demonstrated by using the Na D1 line as an example.
The 1,000th VAD, the Great Rivalry, and the Grand Experiment of the Texas Medical Center

In the closing days of 2013, Dr. O.H. “Bud” Frazier and the Texas Heart Institute (THI) team performed their 1,000th ventricular assist device (VAD) implantation. This landmark achievement occurred barely more than half a century after Dr. Denton A. Cooley founded THI in 1962 as an institution dedicated to reducing the “devastating toll of cardiovascular disease through innovative programs in treatment, education, and research.”1 The 1,000th VAD implantation occurred almost exactly 50 years after the original 1964 National Heart Institute (NHI) grant was awarded to Dr. Michael E. DeBakey and the Baylor College of Medicine for the development of an artificial heart. The juxtaposition in time of these 2 auspicious events would begin a unique and remarkable story—one that would ultimately lead to the realization of VAD implantation as a standard of care after more than 5 decades of ceaseless effort and unrelenting innovation.
Multivalued velocity field model of turbulence

The considered study is based on new theoretical concepts regarding a post-instability model of a fluid discussed by Zak (1980). The model permits the completion of the governing equations of turbulence by introducing multivalued fields of velocities. Attention is given to the mechanism of energy dissipation, the characteristic wave propagation, a simplified model, the formation of turbulence around stagnation points, the formulation of boundary conditions, and the mechanism of turbulence formation. The mechanism of turbulence formation can be understood as propagation of initial discontinuities from the boundaries into a flow with the characteristic velocity which is defined by the normal (to the boundary) velocity components. These components emerge at the boundary as a result of jumps in the tangential components due to the continuity equation.
Moveout-based wave-equation migration velocity analysis

ABSTRACTCurrent wave-equation migration velocity analysis schemes suffer from problems such as severe nonlinearity (which causes the issue of cycle skipping) and imprecise objective functions (which can accrue velocity errors by honoring residuals caused by model complexity and incomplete acquisition). To provide an improvement, we developed an alternative method to perform wave-equation migration velocity analysis by maximizing the flatness of the angle-domain common image gathers. We replaced the ray-based tomographic operator with the wave-equation-based one, although keeping the conventional moveout-based tomography work flow. Instead of maximizing the image-stack-power objective function directly with respect to the slowness, we linked the objective function to the slowness indirectly through an intermediate moveout parameter. By focusing on the common image gather kinematics, this approach greatly reduced the risk of cycle skipping in the absence of low-frequency data, and it produced high-quality g...
Dynamics of the trade balance and the terms of trade in LDCs: The S-curve

Abstract In their analysis of the dynamic behavior of terms of trade and the trade balance, Backus, Kehoe, and Kydland found that the lead and lag correlation between these two variables is S-shaped for a set of OECD countries. Furthermore, they show that this S-curve can be replicated by a two-country dynamic general equilibrium model. Surprisingly, the S-curve also describes the dynamic relationship between terms of trade and the trade balance for a large set of LDCs. This S-curve can also be reproduced by a small-open-economy model which captures some important features of LDC economies. The S-curve is unexpectedly robust to variations in the key parameters of the model. The model also captures the business cycle properties of the LDC data.
Synthesis of 1-aryl-1,2,3-triazole-4,5-dimethanol-4,5-bis(isopropylcarbamates) as potential antineoplastic agents †

Starting with aryl azides, 1-aryl-1,2,3-triazole-4,5-dimethanol-4,5-bis(isopropylcarbamates), a new class of potential antineoplastic agents, were synthesized. In vitro antileukemic and antitumor actmues of the compounds synthesized were also evaluated.
Prediction of airfoil stall in icing conditions using wing surface pressures

Initialworkispresentedonanin-e ightstallmargininstrumentationsystemthatmaintainsaccuracyindependent of wing leading-edge ice formations. The system uses four surface pressures, measured aft of the ice formation, from which the aircraft’ s normalized lift coefe cient is determined. The pressure port locations are selected such that the calibration algorithm remains nearly constant as the leading-edge ice shape and thickness change. Windtunnel data are presented for three ice formations, varying in both type and thickness. The indicated normalized lift coefe cient, based on the no ice algorithm, is compared to the actual normalized lift coefe cient under icing conditions. From this comparison, the four port locations were found to be located at 22 and 41% of the chord on the upper wing surface and 41 and 68% on the lower wing surface.
Highly Efficient Synthesis of the Potent Antitumor Annonaceous Acetogenin (+)-Parviflorin

The annonaceous acetogenins are a rapidly growing class of natural products that have received considerable attention.1 Many members possess a variety of biological effects including potent cytotoxic, antitumor, and pesticidal activities.2,3 Parviflorin (1), a relatively rare C35 adjacent bis-THF acetogenin, was isolated by McLaughlin et al. both from Asimina parViflora Duanl.4a and from Annona bullata Rich.4b Parviflorin showed remarkable selectivity in its cytotoxicity against certain human solid tumor cell lines.5 The relative configuration of 1 was elucidated from spectral analysis,4a and the absolute configuration was determined using Mosher methodology.6 Compound 1 showed spectral data very similar to those of asimicin (2). They share a threo/trans/threo/ trans/threo configuration at the THF core and a hydroxyl group at the C(4) position. While five syntheses of bis-THF acetogenins or their stereoisomers have been reported,7 we now describe a synthetic strategy that significantly improves the overall efficiency for preparation of adjacent bis-THF acetogenins. It culminates in a 14-step synthesis of 1.
Eternal inflation and its implications

I summarize the arguments that strongly suggest that our universe is the product of inflation. The mechanisms that lead to eternal inflation in both new and chaotic models are described. Although the infinity of pocket universes produced by eternal inflation are unobservable, it is argued that eternal inflation has real consequences in terms of the way that predictions are extracted from theoretical models. The ambiguities in defining probabilities in eternally inflating spacetimes are reviewed, with emphasis on the youngness paradox that results from a synchronous gauge regularization technique. Although inflation is generically eternal into the future, it is not eternal into the past: it can be proven under reasonable assumptions that the inflating region must be incomplete in past directions, so some physics other than inflation is needed to describe the past boundary of the inflating region.
Stereochemical control in the metallohalocarbenoid route to linear enediynes

Abstract Methods for the stereoselective preparation and unmasking of disubstituted Z enediynes are reported. The origins of the unprecedented stereoselectivity of the process are uncovered.
Temporal Patterns of Bacterial Mutagenicity on Ambient Aerosols in Southeastern Michigan

The temporal and diurnal patterns of particulate-bound mutagens in the atmosphere were examined for a two-month period in the summer of 1985. Daily PM-10 samples were collected at 0900–2100 and 2100–0900 along with other air quality measurements from a suburban site in southeast Michigan. The paired samples were collected daily in order to examine day/night variations. Each particulate sample was extracted and separated into 16 different fractions based on polarity before Ames tests were conducted on each fraction to determine the bacterial mutagenic activities in TA98 and TA98/DNP6. Other air quality parameters measured included fine particle mass (diameter less than 2.5 μm), sulfate, sulfur dioxide, nitrogen oxides, nitric acid, ozone, carbonaceous aerosols, some trace elements, and pertinent meteorological data. The results show that the four most polar fractions accounted for at least 70% of the mutagenicity. The highest levels of mutagenic activity occurred during two different types of meteorologica...
Diastereo- and regioselective reactions of π-allyl molybdenum complexes with aldehydes

Abstract Remote heteroatom coordination to molybdenum promotes unprecedented selectivity in aldehyde allylation using unsymmetrically substituted allylic metal complexes.
Site-selective conjugation of thiols with aziridine-2-carboxylic acid-containing peptides

The synthesis and convergent site-selective conjugation of aziridine-2-carboxylic acid-containing peptides with thiols, both in solution and on solid support, are described. The synthesis and use of FmocAzyOH in this capacity demonstrate both the efficient incorporation and tolerance of the Azy moiety in multistep Fmoc solid-phase peptide synthesis (SPPS), as well as the competence of solution and on-bead ligation through a highly regioselective base-promoted aziridine ring-opening process.
Lewis Acid Induced Asymmetric Prins Reactions of Chiral Acetals with Alkenes

Abstract Me2AlCl induced reaction of acetal 1 with methylenecyclohexane at -78°C gives a 61% yield of 3 as a 7:3 mixture of diastereomers. MeAlCl2 induced reaction of acetal 2 with methylenecyclohexane gives a 53% yield of 6 as a 7:3 mixture of isomers. Reaction of 1 with isoprene gives 7 as a mixture of all 4 possible isomers. Reaction of acetal 8 with methylenecyclohexane gives the conjugate addition product 9 in 70% yield as a 4:1 mixture of isomers.
Organocatalysis in Radical Chemistry. Enantioselective α-Oxyamination of Aldehydes

We have developed an efficient radical α-oxyamination reaction using chiral organocatalysts. The reaction can be carried out with inexpensive SET reagents, and a reasonably broad substrate scope has been established. Good to high enantioselectivity for the α-oxygenated products are obtained using 20 mol % of the catalyst. The methodology reported in this work adds to the repertoire of asymmetric radical reactions that can be conducted using organocatalysts.
Non-orthogonal Fusion Frames and the Sparsity of Fusion Frame Operators

Fusion frames have become a major tool in the implementation of distributed systems. The effectiveness of fusion frame applications in distributed systems is reflected in the efficiency of the end fusion process. This in turn is reflected in the efficiency of the inversion of the fusion frame operator \(S_{\mathcal{W}}\), which in turn is heavily dependent on the sparsity of \(S_{\mathcal{W}}\). We will show that sparsity of the fusion frame operator naturally exists by introducing a notion of non-orthogonal fusion frames. We show that for a fusion frame {W i ,v i } i∈I , if dim(W i )=k i , then the matrix of the non-orthogonal fusion frame operator \({\mathcal{S}}_{{\mathcal{W}}}\) has in its corresponding location at most a k i ×k i block matrix. We provide necessary and sufficient conditions for which the new fusion frame operator \({\mathcal{S}}_{{\mathcal{W}}}\) is diagonal and/or a multiple of an identity. A set of other critical questions are also addressed. A scheme of multiple fusion frames whose corresponding fusion frame operator becomes an diagonal operator is also examined.
Examining the secondary structures of unnatural peptides and carbohydrate-based compounds utilizing circular dichroism

Abstract This review focuses on the use of CD in elucidating structure in oligo- and polysaccharides, unnatural β- and γ-peptides, and both natural and unnatural oligo- and polymers composed of N-acetyl neuraminic acid. CD in conjunction with other techniques such as NMR and molecular modeling has been successfully used to gain a clearer picture of the hydrogen-bonding interactions, and conformational information of molecules that are not accessible by X-ray crystallography. The use of the peak-to-trough analysis within each class of oligomers has been an integral part of the analysis, and has provided interesting insights into the conformational changes that occur within oligomers with varied chain lengths. Continued studies in this relatively new area of research will add to the knowledge base that correlates circular dichroism data with other spectroscopic techniques ultimately facilitating secondary structure characterization.
Windfarm layout as a senior electrical engineering student design project

A proven senior design project from a wind engineering course is described. Students select equipment, make economic choices, and write a report for a windfarm electrical distribution system. Using topographical maps of potential sites increases realism, helping to make the design project well liked by students. >
Performance improvements of an F-15 airplane with an integrated engine-flight control system

An integrated flight and propulsion control system has been developed and flight demonstrated on the NASA Ames-Dryden F-15 research aircraft. The highly integrated digital control (HIDEC) system provides additional engine thrust by increasing engine pressure ratio (EPR) at intermediate and afterburning power. The amount of EPR uptrim is modulated based on airplane maneuver requirements, flight conditions, and engine information. Engine thrust was increased as much as 10.5 percent at subsonic flight conditions by uptrimming EPR. The additional thrust significantly improved aircraft performance. Rate of climb was increased 14 percent at 40,000 ft and the time to climb from 10,000 to 40,000 ft was reduced 13 percent. A 14 and 24 percent increase in acceleration was obtained at intermediate and maximum power, respectively. The HIDEC logic performed fault free. No engine anomalies were encountered for EPR increases up to 12 percent and for angles of attack and sideslip of 32 and 11 degrees, respectively.
Vibration and sound radiation of sandwich beams with honeycomb truss core

Abstract The vibrations of and the sound radiation from sandwich beams with truss core are analyzed. The structure of the core is composed of a sequence of identical unit cells repeating along the beam length and across the core thickness. Each cell is composed of beam elements assembled to form a frame structure. Layouts with the typical honeycomb pattern arranged through the thickness of the core are here considered. This design represents an alternative with respect to the traditional application of honeycombs in sandwich construction. The proposed configuration provides sandwich beams with interesting structural as well as acoustic characteristics. A finite element model is developed to evaluate the structural and the acoustic behavior of the considered class of sandwich beams. The model is formulated by employing dynamic shape functions, derived directly from the distributed parameter model of beam elements. This formulation, often denoted as “spectral”, allows an accurate evaluation of the dynamic behavior of the considered structures at high frequencies and with a limited number of elements. In addition, the spectral model can be easily coupled with a Fourier transform based analysis of the sound radiated by the fluid-loaded structure. The model is used to analyze the performance of beams with various core configurations. The comparison is carried out in terms of structural response and sound transmission reduction index. In addition the sound pressure levels and distributions resulting from the beam vibration in an unbounded acoustic half-plane are evaluated and compared. Hexagonal and re-entrant configurations are considered in an effort to study the effects of core geometry on structural response and acoustic radiation.
Multifractal Scaling, Geometrical Diversity, and Hierarchical Structure in the Cool Interstellar Medium

Multifractal scaling (MFS) refers to structures that can be described as a collection of interwoven fractal subsets that exhibit power-law spatial-scaling behavior with a range of scaling exponents (concentration, or singularity strengths) and dimensions. The existence of MFS implies an underlying multiplicative (or hierarchical or cascade) process. Panoramic column density images of several nearby star-forming cloud complexes, constructed from IRAS data, are shown to exhibit such multifractal scaling, which we interpret as indirect but quantitative evidence for a nested hierarchical structure. The relation between the dimensions of the subsets and their concentration strengths (the multifractal spectrum) appears to satisfactorily order the observed regions in terms of the mixture of geometries present, from strong pointlike concentrations, to linelike filaments or fronts, to space-filling, diffuse structures. This multifractal spectrum is a global property of the regions studied and does not rely on any operational definition of clouds. The range of forms of the multifractal spectrum among the regions studied implies that the column density structures do not form a universality class, in contrast to indications for velocity and passive scalar fields in incompressible turbulence, providing another indication that the physics of highly compressible interstellar gas dynamics differs fundamentally from incompressible turbulence. There is no correlation between the geometrical properties of the regions studied and their level of internal star formation activity, a result that is also apparent from visual inspection. We discuss the viability of the multifractal spectrum as a measure of the structural complexity of the regions studied and emphasize the problematic dependence of all structural descriptors on the subjective preselection of the region to be described. A comparison of IRAS 100 μm column density (not intensity) images with 13CO, visual extinction, and C18O data suggests that structural details are captured by IRAS up to at least 30 mag of visual extinction, except in the vicinity of embedded stars, and that a lower column density connective structure not seen by other methods is revealed.
Surface-Enhanced Raman Scattering from a Double-Resonance Plasmon Structure

We report surface-enhanced Raman scattering measurements of a benzenethiol monolayer on a double resonance surface plasmon structure. The device enhances excitation and Raman scattered light simultaneously. The largest enhancement factor is measured to be 1.1×108.
Monetary policy regimes in macroeconomic data: An application of fractal analysis

Abstract Macromonetary data are examined for behavioral stability over Alan Greenspan's tenure as chairman of the Federal Reserve System. Strong evidence of stochastic dependence is found using Lo's modified rescaled range tests, though not consistently over the earlier, as opposed to the later, subsample. This finding is suggestive of a change in fundamentals such as monetary policy. Then, five self-affine fractal analysis techniques for estimating the Hurst exponent, Mandelbrot-Levy characteristic exponent, and fractal dimension are employed to explore the data's fractal properties. Techniques are rescaled-range, power-spectral density, roughness-length, variogram, and wavelet analysis. Formal hypothesis tests provide further evidence of a change in monetary policy between the 1989–1996 and 1997–2006 subperiods. This change is manifested both in the behavior and distribution of month-to-month changes in monetary aggregates, ratios, and multipliers, and in the behavior and distribution of macroeconomic data. Most series become significantly less antipersistent after the breakpoint than before. Strong evidence is presented that U.S. monetary policy became actively interventionist after December 1996, and that the effectiveness of the Federal Reserve System has been lowered compared to the earlier period.
The calculation of average distance in mesh structures

Abstract When solving problems in such areas as image processing, computer vision, and computational geometry, within a parallel architecture, the mesh structure often stands out as a natural choice. In this paper, we analyze a scalable measurement of the average distance between two arbitrary but fixed processors in a network structure, which is useful in providing a more global characterization of its data transmission behavior. In particular, we provide a closed-form expression for the average distance between two processors in the case of a traditional mesh. For a more complex case, where a traditional mesh is augmented with some additional diagonal links, after providing a telling expression for the average distance between its two processors, we prove that this latter expression cannot be represented in a closed-form format, with respect to a fairly general class of “standard operations”, namely, the class of the hypergeometric terms. Besides suggesting another global measurement of the communication behavior for general computer networks, and deriving concrete results for some “popular” mesh structures, this paper provides both positive and negative results regarding the derivation of closed-form expressions for combinatorial quantities, thus, is also theoretically interesting. We also believe that some of the general techniques used in this paper should be applicable elsewhere when closed-form expression needs to be derived, or its existence is in question.
Tuning the Position of the Redox Couples in Materials with NASICON Structure by Anionic Substitution

Previous studies on insertion of lithium into rhombohedral forms of and have determined the position of the redox couple to be at 3.6 and 2.8 eV, respectively, below the Fermi level of lithium. Lithium insertion into rhombohedral with NASICON framework exposes the redox couple at 3.3–3.4 eV below the Fermi energy of lithium. Unlike , the insertion of lithium into the structure of is accomplished as a single‐phase solid solution, which makes it attractive as an electrode material for rechargeable lithium batteries.
Optimal design of general stiffened composite circular cylinders for global buckling with strength constraints

A design strategy for optimal design of composite grid-stiffened cylinders subjected to global and local buckling constraints and strength constraints was developed using a discrete optimizer based on a genetic algorithm. An improved smeared stiffener theory was used for the global analysis. Local buckling of skin segments were assessed using a Rayleigh-Ritz method that accounts for material anisotropy. The local buckling of stiffener segments were also assessed. Constraints on the axial membrane strain in the skin and stiffener segments were imposed to include strength criteria in the grid-stiffened cylinder design. Design variables used in this study were the axial and transverse stiffener spacings, stiffener height and thickness, skin laminate stacking sequence and stiffening configuration, where stiffening configuration is a design variable that indicates the combination of axial, transverse and diagonal stiffener in the grid-stiffened cylinder. The design optimization process was adapted to identify the best suited stiffening configurations and stiffener spacings for grid-stiffened composite cylinder with the length and radius of the cylinder, the design in-plane loads and material properties as inputs. The effect of having axial membrane strain constraints in the skin and stiffener segments in the optimization process is also studied for selected stiffening configurations.
Reconstruction and higher-dimensional geometry

Tutte proved that, if two graphs, both with more than two vertices, have the same collection of vertex-deleted subgraphs, then the determinants of the two corresponding adjacency matrices are the same. In this paper, we give a geometric proof of Tutte's theorem using vectors and angles. We further study the lowest eigenspaces of these adjacency matrices.
Magnetic resonance reversals in optically pumped alkali-metal vapor

We report an unusual phenomenon, peculiar sign reversals of the ground-state magnetic resonances and of the zero-dip resonance (Zeeman resonance at zero field) of optically pumped, alkali-metal vapors. These anomalies occur when a weak circularly polarized $D1$ laser light is tuned to pump atoms predominantly from the lower ground-state hyperfine multiplet. One can understand the signal reversals in a simple, semiquantitative way with reference to the spin-temperature distribution. Quantitative computer simulations are in excellent agreement with observations.
Conflations of probability distributions

The conflation of a finite number of probability distributions P 1 , ..., P n is a consolidation of those distributions into a single probability distribution Q = Q(P 1 , ..., P n ), where intuitively Q is the conditional distribution of independent random variables X 1 , ..., X n with distributions P 1 , ..., P n , respectively, given that X 1 = ··· = X n . Thus, in large classes of distributions the conflation is the distribution determined by the normalized product of the probability density or probability mass functions. Q is shown to be the unique probability distribution that minimizes the loss of Shannon information in consolidating the combined information from P 1 , ..., P n into a single distribution Q, and also to be the optimal consolidation of the distributions with respect to two minimax likelihood-ratio criteria. In that sense, conflation may be viewed as an optimal method for combining the results from several different independent experiments. When P 1 , ..., P n are Gaussian, Q is Gaussian with mean the classical weighted-mean-squares reciprocal of variances. A version of the classical convolution theorem holds for conflations of a large class of a.c. measures.
Connectivity-based localization of large-scale sensor networks with complex shape

We study the problem of localizing a large sensor network having a complex shape, possibly with holes. A major challenge with respect to such networks is to figure out the correct network layout, that is, avoid global flips where a part of the network folds on top of another. Our algorithm first selects landmarks on network boundaries with sufficient density, then constructs the landmark Voronoi diagram and its dual combinatorial Delaunay complex on these landmarks. The key insight is that the combinatorial Delaunay complex is provably globally rigid and has a unique realization in the plane. Thus an embedding of the landmarks by simply gluing the Delaunay triangles properly recovers the faithful network layout. With the landmarks nicely localized, the rest of the nodes can easily localize themselves by trilateration to nearby landmark nodes. This leads to a practical and accurate localization algorithm for large networks using only network connectivity. Simulations on various network topologies show surprisingly good results. In comparison, previous connectivity-based localization algorithms such as multidimensional scaling and rubberband representation generate globally flipped or distorted localization results.
Protostar Formation in Magnetic Molecular Clouds beyond Ion Detachment. I. Formulation of the Problem and Method of Solution

We formulate the problem of the formation of magnetically supercritical cores in magnetically subcritical parent molecular clouds, and the subsequent collapse of the cores to high densities, past the detachment of ions from magnetic field lines and into the opaque regime. We employ the six-fluid MHD equations, accounting for the effects of grains (negative, positive, and neutral) including their inelastic collisions with other species. We do not assume that the magnetic flux is frozen in any of the charged species. We derive a generalized Ohm's law that explicitly distinguishes between flux advection (and the associated process of ambipolar diffusion) and Ohmic dissipation, in order to assess the contribution of each mechanism to the increase of the mass-to-flux ratio of the central parts of a collapsing core and possibly to the resolution of the magnetic flux problem of star formation. The results, including a detailed parameter study, are presented in two accompanying papers.
The Challenges to Coupling Dynamic Geospatial Models

ABSTRACT Many applications of modeling spatial dynamic systems focus on a single system and a single process, ignoring the geographic and systemic context of the processes being modeled. A solution to this problem is the coupled modeling of spatial dynamic systems. Coupled modeling is challenging for technical reasons, as well as conceptual reasons. This paper explores the benefits and challenges to coupling or linking spatial dynamic models, from loose coupling, where information transfer between models is done by hand, to tight coupling, where two (or more) models are merged as one. To illustrate the challenges, a coupled model of Urbanization and Wildfire Risk is presented. This model, called Vesta, was applied to the Santa Barbara, California region (using real geospatial data), where Urbanization and Wildfires occur and recur, respectively. The preliminary results of the model coupling illustrate that coupled modeling can lead to insight into the consequences of processes acting on their own.
Media Use, Democratic Citizenship, and Communication Gaps in a Developing Democracy

In contrast to most previous scholarship that has examined political communication gaps within developed polities, this study examines the role of such gaps in a developing democracy with high levels of social stratification. Employing the 2001 Afrobarometer survey conducted in Mali, this study examined the association between forms of media use (radio, newspaper, and television) and individual political knowledge, participation, and socialization. The analysis demonstrates a pattern of political communication gaps where media use is associated with a widening of gaps in political knowledge and participation favoring socially privileged groups. Conversely, media use is associated with a narrowing of gaps in democratic socialization between social groups. These findings have implications for understanding the institutional and systemic role of the mass media in developing democracies.
On the Collapse of Tubes Carried¶by 3D Incompressible Flows

We define the notion of a “regular tube”, and prove that a regular tube convected by a 3D incompressible flow cannot collapse to zero thickness in finite time.
Algebraic Theory of Linear Viscoelastic Nematodynamics

This paper consists of two parts. The first one develops algebraic theory of linear anisotropic nematic “N-operators” build up on the additive group of traceless second rank 3D tensors. These operators have been implicitly used in continual theories of nematic liquid crystals and weakly elastic nematic elastomers. It is shown that there exists a non-commutative, multiplicative group N6 of N-operators build up on a manifold in 6D space of parameters. Positive N-operators, which in physical applications hold thermodynamic stability constraints, do not generally form a subgroup of group N6. A three-parametric, commutative transversal-isotropic subgroup \({\text{S}}_{\text{3}}\subset {\text{N}}_{\text{6}} \) of positive symmetric nematic operators is also briefly discussed. The special case of singular, non-negative symmetric N-operators reveals the algebraic structure of nematic soft deformation modes. The second part of the paper develops a theory of linear viscoelastic nematodynamics applicable to liquid crystalline polymer. The viscous and elastic nematic components in theory are described by using the Leslie–Ericksen–Parodi (LEP) approach for viscous nematics and de Gennes free energy for weakly elastic nematic elastomers. The case of applied external magnetic field exemplifies the occurrence of non-symmetric stresses. In spite of multi-(10) parametric character of the theory, the use of nematic operators presents it in a transparent form. When the magnetic field is absent, the theory is simplified for symmetric case with six parameters, and takes an extremely simple, two-parametric form for viscoelastic nematodynamics with possible soft deformation modes. It is shown that the linear nematodynamics is always reducible to the LEP-like equations where the coefficients are changed for linear memory functionals whose parameters are calculated from original viscosities and moduli.
Deposition of biaxially-oriented metal and oxide buffer-layer films on textured Ni tapes: new substrates for high-current, high-temperature superconductors

Abstract Techniques are reported for sputter deposition of biaxially oriented buffer-layers on textured Ni tapes. These buffered tapes can be employed as long, flexible, or large area substrates for biaxially-aligned high-temperature superconductors (HTS) with high critical current density Jc. Using deposition techniques at temperatures as low as 25°C, epitaxial Pd or Pt films were first deposited as a base layer on the textured Ni tapes, followed by deposition of biaxially oriented Ag or CeO2 buffer layers. Using Ar/4%H2 sputter gas, biaxially oriented CeO2 films were also grown directly on the textured Ni tapes, followed by the epitaxial growth of YSZ films. All the films show both strong in-plane and out-of-plane orientations. The effects of Ni surface smoothness on buffer-layer texture were also investigated.
Programming language semantics

A programming language possesses syntax and semantics. Syntax refers to the spelling of the language’s programs, and semantics refers to the meanings of the programs. A language’s syntax is formalized by a grammar or syntax chart; such formalizations are found in the back of language manuals. A language’s semantics should be formalized, too, and this is the topic of this chapter. Before we begin, we might ask, “What do we gain by formalizing the semantics of a programming language?” Consider the related question, “What was gained when language syntax was formalized with BNF?” • A language’s syntax definition standardizes the official syntax. This is crucial to users, who require a guide to writing syntactically correct programs, and to implementors, who must write a correct parser for the language’s compiler. • The syntax definition permits a formal analysis of its properties, such as whether the definition is LL(k), LR(k), or ambiguous. • The syntax definition can be used as input to a compiler front-end generating tool, such as YACC; it becomes, in effect, the implementation. We derive similar benefits from a formal semantics definition: • The semantics definition standardizes the official semanticsof the language. This is crucial to users, who require a guide to understanding the programs that they write, and to implementors, who must write a correct code generator for the language’s compiler. • The semantics definition permits a formal analysis of its properties, such as whether the definition is strongly typed, block structured, uses single-threaded data structures, is parallelizable, etc. • The semantics definition can be used as input to a compiler back-end generating tool [26, 31]; it becomes, in effect, the implementation. Programming-language syntax was studied intensively in the 1960’s and 1970’s, and programming language semantics is undergoing similar intensive study. Unlike the acceptance of BNF as the standard for syntax definition, it is unlikely that a single definition method will take hold for semantics—semantics is harder to formalize than syntax, and it has a wider variety of applications. Semantics-definition methods fall roughly into three groups:
Inductive Energy Storage for MPD Thrusters

The high thrust density of the self-field magnetoplasmadynamic (MPD) thruster makes it a promising candidate for many advanced space missions. The high power requirements of this thruster lead to its operation in a pulsed mode from an energy storage device. The system characteristics of an inductive energy storage circuit with a solar array power from 25 kwe to 400 kwe are considered, by solving the circuit equations for the inductor charge and discharge phases. Using simple analytic models of the circuit components, the total system efficiency and inductance are determined as functions of the array output power and circuit resistance. The total system efficiency increases with array power and is acceptable only for low values of circuit resistance, indicating that superconducting circuitry may be desirable. The optimum charge-discharge cycle changes fundamentally as the circuit resistance is decreased through a critical value dependent on the thruster operating characteristics.
Graft engineering using ex vivo methods to limit GvHD: Fludarabine treatment generates superior GvL effects in allogeneic BMT

Objective To compare the abilities of different ex vivo methods of treating donor lymphocytes to inhibit graft-vs-host disease (GVHD) while preserving graft-vs-leukemia (GVL) activity in murine models of allogeneic bone marrow transplantation. Methods Donor/recipient pairs included MHC fully mismatched, MHC haplomismatched, and MiHA mismatched strain combinations. T cell–depleted BM (TCD-BM) was transplanted in combination with untreated, fludarabine-treated, 7.5-Gy γ-irradiated, or psoralen/UVA (PUVA)-treated splenocytes. GVL activity was studied by adding a lethal number of recipient-type lymphoma cells. Posttransplant survival was determined, and GVHD and GVL activity were assessed by clinical and pathological scoring. Hematopoietic chimerism and donor T-cell expansion were analyzed by flow cytometry of peripheral blood samples at 30 and 60 days posttransplant. Results Allogeneic splenocytes treated with fludarabine, 7.5 Gy γ-irradiation, or PUVA had significantly diminished GVHD activity, and all treated donor T cells facilitated engraftment by low-dose TCD-BM. Allogeneic splenocytes treated with fludarabine and, to a lesser extent, PUVA retained GVL activity and contributed more to donor T-cell chimerism compared to γ-irradiated donor splenocytes. Conclusion Among ex vivo methods of treating donor T cells to limit their proliferative capacity, fludarabine exposure had the greatest differential ability to inhibit the GVHD activity of allogeneic lymphocytes, while preserving their GVL activity and ability to engraft recipients. Thus, ex vivo treatment with fludarabine was superior to γ-irradiation or PUVA in separating GVL from GVHD activity in murine models of allogeneic bone marrow transplantation.
The Molecule-rich Tail of the Peculiar Galaxy NGC 2782 (Arp 215)

We present the first detection of a large quantity of molecular gas in the extended tail of an interacting galaxy. Using the NRAO 12 m telescope, we have detected CO (1–0) at five locations in the eastern tail of the peculiar starburst galaxy NGC 2782. The CO velocities and narrow (FWHM ~ 50 km s-1) line widths in these positions agree with those seen in H I, which confirms that the molecular gas is indeed associated with the tail rather than the main disk. As noted previously, the gas in this tail has an apparent "counterrotation" compared to gas in the core of the galaxy, probably because the tails do not lie in the same plane as the disk. Assuming the standard Galactic conversion N/ICO factor, these observations indicate a total molecular gas mass of 6 × 108 M⊙ in this tail. This may be an underestimate of the total H2 mass if the gas is metal poor. This molecular gas mass, and the implied H2/H I mass ratio of 0.6, are higher than that found in many dwarf irregular galaxies. Comparison with an available Hα map of this galaxy, however, shows that the rate of star formation in this feature is extremely low relative to the available molecular gas, compared to LHα/M values for both spiral and irregular galaxies. Thus, the timescale for depletion of the gas in this feature is very long.
Fan Inlet Disturbances and Their Effect on Static Acoustic Data

There is evidence that measurements of fan-rotor inlet noise taken during static test situations are at variance with aircraft engine flight data. In particular, static tests generally yield a significantly higher tone at blade passing frequency than that measured during flight. An experimental program was carried out to investigate this discrepancy. Inlet ground vortices and large-scale inlet turbulence were generated intentionally in an anechoic test chamber. Far-field acoustic measurements and inlet flow field hot film mappings of a fan rotor were then carried out to study the influence of such inlet disturbances at a static test facility. Experimental results indicate that the acoustic effect of such disturbances appears to be less severe for supersonic than for subsonic tip speeds. Further, a reverse flow that occurs on the exterior cowl in static test facilities appears to be an additional prime candidate for creating inlet disturbances and causing variance between flight and static acoustic data.
Twisting of X-Ray Isophotes in Triaxial Galaxies

We investigate X-ray isophote twists created by triaxiality differences between the luminous stellar distributions and the dark halos in elliptical galaxies. For a typically oblate luminous galaxy embedded in a more prolate halo formed by dissipationless collapse, the triaxiality difference of ΔT 0.7 leads to typical isophote twists of ΔψX 16° ± 19° at 3 effective stellar radii. In a model that includes baryonic dissipation, the effect is smaller, with ΔT 0.3 and ΔψX 5° ± 8°. Thus, accurate measurements of X-ray isophote twists may be able to set constraints on the interactions between baryons and dissipationless dark matter during galaxy formation. The 30° X-ray isophote twist in the E4 galaxy NGC 720 cannot be reproduced by our model, suggesting an intrinsic misalignment between the halo and the stars rather than a projection effect.
Generation and Utility of Tertiary α-Aminoorganolithium Reagents

A general approach to tertiary α-aminoorganolithium reagents by reductive lithiation of α-aminonitriles has been developed. This class of organolithium nucleophiles reacts efficiently with carbonyl electrophiles or in intramolecular cyclizations with tethered phosphate leaving groups. Transmetalation can be used to produce α-aminoorganocuprate reagents that react with alkyl halide electrophiles and in 1,4-additions with enones. These methods establish a new approach for the synthesis of quaternary centers adjacent to nitrogen.