cssi/SciSciGPT-SciSciNet huggingface dataset:
Measuring the effects of distributed database models on transaction availability measures

Abstract Data distribution, data replication and system reliability are key factors in determining the availability measures for transactions in distributed database systems. In order to simplify the evaluation of these measures, database designers and researchers tend to make unrealistic assumptions about these factors. In this article, we investigate the effect of such assumptions on the computational complexity and accuracy of such evaluations. We represent a database system with five parameters related to the above factors. Probabilistic analysis is employed to evaluate the availability of read-only and read-write transactions. We consider both the read-one/write-all and the majority-read/majority-write replication control policies. We conclude that transaction availability is more sensitive to variations in degrees of replication, less sensitive to data distribution, and insensitive to reliability variations in a nonhomogeneous system. The computational complexity of the evaluations is found to be mainly determined by the chosen distributed database model, while the accuracy of the results is not so much dependent on the models.
LOUPING ILL IN MAN.

Four instances of infection in man which are believed, because of the circumstances under which they occurred and in view of the results of neutralization tests, to represent cases of louping ill have been described. Evidence obtained by the neutralization tests is in favor of the idea that the antibodies against louping ill virus demonstrated in certain sera were most likely the result either of contact with or of infection with the active agent.
Solar and Stellar Magnetic Fields and Atmospheric Structures - Theory

This presentation reviews selected ideas on the origin of the magnetic field of the Sun, the dynamical behavior of the azimuthal field in the convective zone, the fibril state of the field at the photosphere, the formation of sunspots, prominences, the spontaneous formation of current sheets in the bipolar field above the surface of the Sun, coronal heating, and flares.
Counting independent sets in triangle-free graphs

Ajtai, Komlos, and Szemeredi proved that for sufficiently large t every trianglefree graph with n vertices and average degree t has an independent set of size at least n 100t log t. We extend this by proving that the number of independent sets in such a graph is at least 2 1 2400 n t log . This result is sharp for infinitely many t, n apart from the constant. An easy consequence of our result is that there exists c′ > 0 such that every n-vertex triangle-free graph has at least 2 ′n logn independent sets. We conjecture that the exponent above can be improved to √ n(log n)3/2. This would be sharp by the celebrated result of Kim which shows that the Ramsey number R(3, k) has order of magnitude k2/ log k.
Multilayer relaxation in metallic surfaces as demonstrated by LEED analysis

Abstract Theoretical motivations are reviewed for investigation of multilayer relaxation in relatively simple metallic surfaces. Results from LEED analyses are presented which serve to demonstrate that multilayer relaxation measurably exists in Cu(100) and Cu(110) surfaces. The results from two independent LEED analyses for Cu(110) are shown to be in much better agreement with each other than the LEED results are with multilayer relaxation results obtained by high energy ion scattering. Multilayer relaxation results for other metallic surfaces also are reviewed briefly, and all available results are discussed in relationship to those obtained by a theoretical, model-type, inquiry of Landman, Hill and Mostoller.
Evidence for direct molecular oxygen production in CO2 photodissociation

Photodissociation of carbon dioxide (CO2) has long been assumed to proceed exclusively to carbon monoxide (CO) and oxygen atom (O) primary products. However, recent theoretical calculations suggested that an exit channel to produce C + O2 should also be energetically accessible. Here we report the direct experimental evidence for the C + O2 channel in CO2 photodissociation near the energetic threshold of the C((3)P) + O2(X(3)Σ(g)(-)) channel with a yield of 5 ± 2% using vacuum ultraviolet laser pump-probe spectroscopy and velocity-map imaging detection of the C((3)PJ) product between 101.5 and 107.2 nanometers. Our results may have implications for nonbiological oxygen production in CO2-heavy atmospheres.
Stoichiometric reactions of nonconjugated dienes with zirconocene derivatives. Further delineation of the scope of bicyclization and observation of novel multipositional alkene regioisomerization

Abstract The reaction of n-Bu2ZrCp2 with nonconjugated dienes containing substituted vinyl groups can lead to either bicyclization or the formation of conjugated diene-zirconocenes via multipositional regioisomerization.
Zeros of Weakly Holomorphic Modular Forms of Levels 2 and 3

Let $M_k^\sharp(N)$ be the space of weakly holomorphic modular forms for $\Gamma_0(N)$ that are holomorphic at all cusps except possibly at $\infty$. We study a canonical basis for $M_k^\sharp(2)$ and $M_k^\sharp(3)$ and prove that almost all modular forms in this basis have the property that the majority of their zeros in a fundamental domain lie on a lower boundary arc of the fundamental domain.
Palladium-catalyzed cyanation of hindered, electron-rich aryl triflates by zinc cyanide

Abstract We examined the palladium-catalyzed cyanation of hindered, electron-rich aryl triflates by zinc cyanide using 2-methoxyphenyl trifluoromethanesulfonate ( 4 ) as a model compound. The reaction with two equivalents of Zn(CN) 2 and catalytic Pd(PPh 3 ) 4 in DMF at 120°C for 2 hr afforded 2-methoxy-benzonitrile ( 5 ) in 81% yield. The synthesis of 3-cyano-3-desoxynaltrexone( 3 ), which had not previouly been obtained by the reaction with potassium or sodium cyanide as a cyanide source, was achieved by applying this procedure to its corresponding triflate 2 .
Characterization of resin types from the Hiawatha seam of the Wasatch Plateau coal field

Abstract Fossil resin types occurring in the Hiawatha seam of the Wasatch Plateau coal field, Utah, have been separated according to color and their physical and chemical properties evaluated. These resin types were separated into four color fractions—yellow, amber, light-brown, and dark-brown. Each resin type has then been subjected to comprehensive spectroscopic examination and other physical methods of characterization. Included among the spectroscopic methods of characterization are FTIR and 13 C NMR spectroscopy. Physical properties that have been measured include density, optical, and magnetic properties. These analyses reveal that the resins are distinct from other coal macerals, having low aromaticity with small amounts of oxygen functionalities and a low degree of unsaturation. The four resin types show distinct differences in certain physical and chemical properties such as density, hexane solubility, magnetic susceptibility, and aromaticity.
Energies, transition rates, and electron electric-dipole-moment enhancement factors for Ce IV and Pr V

Energies, transition rates, and electron electric-dipole-moment (EDM) enhancement factors are calculated for low-lying states of Ce IV and Pr V using relativistic many-body perturbation theory. This study is related to recent investigations of the more complicated Gd IV ion, which is promising for electron EDM experiments. The ions Ce IV and Pr V both have a single valence electron, permitting one to carry out reliable ab initio calculations of energy levels, transition rates, and other atomic properties using well-developed computational methods.
Exact noncommutative solitons

We find exact solitons in a large class of noncommutative gauge theories using a simple solution generating technique. The solitons in the effective field theory description of open string field theory are interpreted as D-branes for any value of the noncommutativity. We discuss the vacuum structure of open string field theory in view of our results.
Density profile and flow of miscible fluid with dissimilar constituent masses

Abstract A computer simulation model is used to study the density profile and flow of a miscible gaseous fluid mixture consisting of differing constituent masses ( m A = m B /3) through an open matrix. The density profile is found to decay with the height ∝ exp (−m A(B) h) , consistent with the barometric height law. The flux density shows a power-law increase ∝( p c − p ) μ with μ ≃2.3 at the porosity 1− p above the pore percolation threshold 1− p c .
Area-preserving structure and anomalies in 1+1-dimensional quantum gravity

We investigate the gauge-independent Hamiltonian formulation and the anomalous Ward identities of a matter-induced 1+1-dimensional gravity theory invariant under Weyl transformations and area-preserving diffeomorphisms, and compare the results to the ones for the conventional diffeomorphism-invariant theory. We find that, in spite of several technical differences encountered in the analysis, the two theories are essentially equivalent.
Molecular dynamics simulations of biological reactions.

This review considers the author perspective on the emergence of molecular dynamics (MD) simulations of biological processes. It starts with the 1976 simulation of the primary event in rhodopsin, moves to the earliest simulations of enzymatic reactions and electron transfer reactions and ends up with recent simulations of proton translocations and ion transport in proteins. The emphasis is placed on our progress in simulations of actual biological reactions and functional properties, rather than on studies of general properties such as structure and thermal motions. In most cases it has been possible to develop special strategies that capture the relevant dynamics of the given biological process. The predictive power of our early simulations of fast biological process (e.g. vision and photosynthesis) and the insight obtained from these studies is pointed out. Critical examinations of dynamical effects in different biological processes is reviewed. This includes the finding that dynamical effects are unlikely to contribute significantly to enzyme catalysis or to other processes with significant activation barriers. Even in the case of ion channels it is found that the most important effects are associated with energetics rather than dynamics. Nevertheless, MD simulations provide what is probably the most realistic description of the actual reactive events. The resulting insight is crucial in studies of fast photobiological reactions and instructive in cases of slower processes.
Optimal kinematics and morphologies for spermatozoa.

We investigate the role of hydrodynamics in the evolution of the morphology and the selection of kinematics in simple uniflagellated microorganisms. We find that the most efficient swimming strategies are characterized by symmetrical, nonsinusoidal bending waves propagating from the base of the head to the tip of the tail. In addition, we show that the ideal tail-to-head length ratio for such a swimmer is $\ensuremath{\approx}12$ and that this predicted ratio is consistent with data collected from over 400 species of mammalian sperm.
Tight bounds for oblivious routing in the hypercube

We prove that in anyN-node communication network with maximum degreed, any deterministic oblivious algorithm for routing an arbitrary permutation requires Ω(√N/d) parallel communication steps in the worst case. This is an improvement upon the Ω(√N/d 3/2) bound obtained by Borodin and Hopcroft. For theN-node hypercube, in particular, we show a matching upper bound by exhibiting a deterministic oblivious algorithm that routes any permutation in Θ(√N/logN) steps. The best previously known upper bound was Θ(√N). Our algorithm may be practical for smallN (up to about 214 nodes).
Monte Carlo and Navier-Stokes Simulations of Compressible Taylor-Couette Flow

The compressible Taylor-Couette flow between concentric cylinders, in the case where the inner cylinder is rotating and the outer one is at rest, has been computed using a Direct Simulation Monte Carlo (DSMC) method and a pseudo-spectral/finite difference method. Depending on the air gap pressure, the flow in between the cylinders may be characterized by a variety of flow regimes ranging from free molecular to continuum, laminar to turbulent flow and by the presence of steady or unsteady toroidal vortices. In related new experiments performed by the Center for Electromechanics at the University of Texas at Austin, the pressure ranged from about 10 Pa to 1000 Pa. For the low-pressure cases (~10 Pa) the experiments are compared to the DSMC results while the high-pressure cases (~1000 Pa) are compared to the Direct Numerical Simulation results. For the intermediate cases (~100 Pa), both methods are used. At Taylor numbers of about 1-5, the velocity slips about 10% at the walls. At higher Taylor numbers between 10-50, the velocity slip decreases to about 1%, and at even higher Taylor numbers, the velocity profiles exhibit essentially no slip. Similarly, temperature slip at the walls decreases as the Taylor number increases. At low pressures, the velocity profile is roughly linear and the temperature profile has a parabolic shape. At high pressures, Taylor vortices are present in the gap and the axially averaged velocity profile evolves into an “S-shape” profile while the temperature parabola becomes flatter in the center of the gap. The simulated work required to rotate the inner cylinder and the heat flux to the walls are compared to experiments: agreement is good over the entire range of Taylor numbers.
Structural change and economic growth

This paper presents a model in which a country's measured average propensity to save endogenously rises when its economy industrializes. The model has agricultural and manufacturing sectors. Only agriculture uses land. If at early dates income per capita is low, agricultural consumption is important, land is valuable, and capital gains on land may constitute most wealth accumulation, leaving the country's NIPA APS low. If exogenous technological progress raises incomes over time, Engel's law shifts demand to manufactured goods. Then land's portfolio importance relative to reproducible capital diminishes and the national income and products account saving rate can rise. This paper presents a model illustrating that structural change due to the operation of Engel's law can systematically affect an economy's measured saving rate. According to the model, a country's national income and product account average propensity to save will rise naturally if and when technological progress sufficiently lifts its income per capita. This suggests a new interpretation of time series evidence: while saving rates historically tend to be higher after industrialization than before, one cannot automatically infer that changing wealth-accumulation behaviour led to modernization-rather, structural change accompanying growth may have caused the rise in saving rates. This paper also warns that international trade could lead to a contrasting pattern in cross sectional data: highincome nations might contemporaneously have lower measured saving rates than poor countries. Recent work by Mankiw, Romer and Weil (1992), Islam (1995), Mankiw (1995), and others investigates long-run patterns. The analyses assume that each economy has attained, or is moving toward, a steady state equilibrium. As in Solow (1956), a country's steady-state level of per capita GDP depends on its average propensity to save (APS), its rate of population growth, the efficiency of its production sector, etc. Regression outcomes seem consistent with the Solow model's prediction that a higher APS will, ceteris paribus, lead to a higher level of income per capita. The idea is that heterogeneity of exogenous preferences leads to international differences in APS's and, in turn, to long-run differences
Solution and solid-support synthesis of a potential leishmaniasis carbohydrate vaccine.

The synthesis of a potential carbohydrate vaccine for the parasitic disease leishmaniasis is described. New solution- and solid-phase synthetic strategies were explored for the assembly of a unique tetrasaccharide antigen found on the Leishmania lipophosphoglycan. An initial solution-phase synthesis relied on thioglycosides as building blocks and the establishment of the central disaccharide from lactal via an oxidation−reduction sequence. A second approach was completed both in solution and on solid support. The solid-phase synthesis relied on assembly from monosaccharide units and was used to evaluate different glycosylating agents in the efficient installation of the galactose β-(1→4) mannoside. Glycosyl phosphates proved most successful in this endeavor. This first solid-phase synthesis of the Leishmania cap provided rapid access to the tetrasaccharide in 18% overall yield while requiring only a single purification step. The synthetic cap tetrasaccharide was conjugated to the immunostimulator Pam3Cys ...
Non-gravitational heating in the hierarchical formation of X-ray clusters

The strong deviation in the properties of X-ray clusters from simple scaling laws highlights the importance of non-gravitational heating and cooling processes in the evolution of protocluster gas. We investigate this from two directions: by finding the amount of ‘excess energy’ required in intracluster gas in order to reproduce the observed X-ray cluster properties, and by studying the excess energies obtained from supernovae in a semi-analytic model of galaxy formation. Using the insights obtained from the model, we then critically discuss possible ways of achieving the high excess specific energies required in clusters. These include heating by supernovae and active galactic nuclei, the role of entropy, and the effect of removing gas through radiative cooling. Our model self-consistently follows the production of excess energy and its effect on gas haloes. Excess energy is retained in the gas as gravitational, kinetic and/or thermal energy. The density profile of a gas halo is then selected according to the total energy of the gas. Our principal assumption is that in the absence of non-gravitational processes, the total energy of the gas scales as the gravitational energy of the virialized halo – a self-similar scaling law motivated by hydrodynamic simulations. This relation is normalized by matching the model to the largest observed clusters. We model the gas distributions in haloes by using a two-parameter family of gas profiles. In order to study the sensitivity of results to the model, we investigate four contrasting ways of modifying gas profiles in the presence of excess energy. In addition, we estimate the minimum excess energy required in a fiducial cluster of around 2 keV in temperature by considering all available gas profiles. We conclude that the excess energies required lie roughly in the range 1–3 keV particle−1. The observed metallicities of cluster gas suggest that it may be possible for supernovae to provide all of the required excess energy. However, we argue that this scenario is only marginally acceptable and would lead to highly contrived models of galaxy formation. On the other hand, more than enough energy may be available from active galactic nuclei.
Active space debris charging for contactless electrostatic disposal maneuvers

Abstract The remote charging of a passive object using an electron beam enables touchless re-orbiting of large space debris from geosynchronous orbit (GEO) using electrostatic forces. The advantage of this method is that it can operate with a separation distance of multiple craft radii, thus reducing the risk of collision. The charging of the tug–debris system to high potentials is achieved by active charge transfer using a directed electron beam. Optimal potential distributions using isolated- and coupled-sphere models are discussed. A simple charging model takes into account the primary electron beam current, ultra-violet radiation induced photoelectron emission, collection of plasma particles, secondary electron emission and the recapture of emitted particles. The results show that through active charging in a GEO space environment high potentials can be both achieved and maintained with about a 75% transfer efficiency. Further, the maximum electrostatic tractor force is shown to be insensitive to beam current levels. This latter later result is important when considering debris with unknown properties.
Challenges to the practical implementation of modeling and valuing real options

A great deal of theoretical work exists on how to model and value investment opportunities having real options. To date, this work has provided new insights into capital budgeting decision-making and a new decision-making framework. However, the currently proposed real option models are not widely used by corporate managers and practitioners. The question is, “Why not?” This paper posits one possible answer to that question. Specifically, this paper reviews what has been accomplished in modeling and valuing real options and examines practical implementation problems associated with the real option approach. The issues examined are: (1) The types of models currently used are not well known or understood by corporate managers and practitioners; (2) The required modeling assumptions are often violated in a practical real option application; and (3) The necessary additional assumptions required for mathematical tractability limit the scope of applicability. We then discuss possible alternatives for modeling and valuing real options that capture the essence of the problem, but do so in a simpler framework. This paper demonstrates the need to identify and develop alternative frameworks for practically modeling and valuing real options.
The structure and reactivity of iron nitride complexes

The structure and reactivity of discrete iron nitride complexes is described. Six-coordinate, four-fold symmetric nitrides are thermally unstable, and have been characterized at cryogenic temperatures by an arsenal of spectroscopic methods. By contrast, four-coordinate, three-fold symmetric iron nitrides can be prepared at room temperature. A range of diamagnetic iron(IV) nitrides have been reported and in some cases, isolated. Among these are the isolable, yet reactive, tris(carbene)borate iron(IV) nitrides. These complexes can effect two-electron nitrogen atom transfer to a range of substrates, in some cases with complete atom transfer occuring through Fe–N bond cleavage. These nitrides are also active in single electron pathways, including the synthesis of ammonia by a mechanism involving hydrogen atom transfer to the nitride ligand. One-electron oxidation of a tris(carbene)borate iron(IV) nitride leads to an isolable iron(V) complex that is unusually reactive for a metal nitride.
A compiled picture language on Macintosh

A visual programming language for Macintosh personal computer system is introduced. In this language both programs and data are pictures. Keyboardless programming is the main goal of the language design. The language is designed for novice users such as school children. An interpreter version of the language implementation is now available on 512K Macintosh. An overview of a compiler version, which is currently being tested, is given.
Feature extraction using molecular planes for fuzzy relational clustering of a flexible dopamine reuptake inhibitor

Six rigid-body parameters (Shift, Slide, Rise, Tilt, Roll, Twist) are commonly used to describe the relative displacement and orientation of successive base pairs in a nucleic acid structure. The present work adapts this approach to describe the relative displacement and orientation of any two planes in an arbitrary moleculespecifically, planes which contain important pharmacophore elements. Relevant code from the 3DNA software package (Nucleic Acids Res. 2003, 31, 5108−5121) was generalized to treat molecular fragments other than DNA bases as input for the calculation of the corresponding rigid-body (or “planes”) parameters. These parameters were used to construct feature vectors for a fuzzy relational clustering study of over 700 conformations of a flexible analogue of the dopamine reuptake inhibitor, GBR 12909. Several cluster validity measures were used to determine the optimal number of clusters. Translational (Shift, Slide, Rise) rather than rotational (Tilt, Roll, Twist) features dominate clusterin...
Pigouvian pricing and stochastic evolutionary implementation

Abstract We study the implementation of efficient behavior in settings with externalities. A planner would like to ensure that a group of agents make socially optimal choices, but he only has limited information about the agents’ preferences, and can only distinguish individual agents through the actions they choose. We describe the agents’ behavior using a stochastic evolutionary model, assuming that their choice probabilities are given by the logit choice rule. We prove that there is a simple price scheme with the following property: regardless of the realization of preferences, a group of agents subjected to the price scheme will spend the vast majority of time in the long run behaving efficiently. The price scheme defines a game that may possess multiple equilibria, but we are able to obtain a unique and efficient selection from this set because of the stochastic nature of the agents’ choice rule. We conclude by comparing the performance of our price scheme with that of VCG mechanisms.
Optical Sources near the Bright X-Ray Source in NGC 1073

New HST observations show that the bright X-ray source in the face-on spiral galaxy NGC 1073 is located near a ring of recent star formation with an age of 8-16 Myr. This strengthens the association of X-ray sources in spiral galaxies emitting near or above the Eddington limit for a 20 M☉ black hole with recent star formation events. Two candidate optical counterparts of the X-ray source are found. The X-ray-to-optical flux ratios of both are consistent with those of low-mass X-ray binaries and higher than most high-mass X-ray binaries, suggesting that reprocessing of X-rays contributes to the optical light. The optical magnitude and color of one candidate is consistent with that predicted for an X-ray binary with an initial donor mass of 6-8 M☉. However, the same X-ray binary evolution model underestimates the X-ray luminosity. An X-ray source list for the field is presented, which includes detections of the nucleus of NGC 1073, three quasars, and an M3e brown dwarf star with high proper motion.
Tax policy, housing prices, and housing investment☆

Abstract This paper employs a general equilibrium model with forward-looking behavior and adjustment dynamics to assess the effects of major components of the Tax Reform Act of 1986 on housing and other industries. Simulation results reveal significant differences between effects on housing and other industries as well as substantial changes over time. While the major tax reforms promote an expansion of the housing sector in the short run, they have a negative influence on both real housing investment and the total value of housing assets over the longer term. These negative long-run consequences stem from adverse effects which these reforms have on economy-wide output and real incomes.
Granular discharge and clogging for tilted hoppers

We measure the flux of spherical glass beads through a hole as a systematic function of both tilt angle and hole diameter, for two different size beads. The discharge increases with hole diameter in accord with the Beverloo relation for both horizontal and vertical holes, but in the latter case with a larger small-hole cutoff. For large holes the flux decreases linearly in cosine of the tilt angle, vanishing smoothly somewhat below the angle of repose. For small holes it vanishes abruptly at a smaller angle. The conditions for zero flux are discussed in the context of a clogging phase diagram of flow state vs tilt angle and ratio of hole to grain size.
DENSITY PROBABILITY DISTRIBUTION FUNCTIONS IN SUPERSONIC HYDRODYNAMIC AND MHD TURBULENCE

We study the probability distribution function (PDF) of the mass density in simulations of supersonic turbulence with properties appropriate for molecular clouds. For this study we use Athena, a new higher-order Godunov code. We find there are surprisingly similar relationships between the mean of the time-averaged PDF and the turbulent Mach number for driven hydrodynamic and strong-field MHD turbulence. There is, however, a large scatter about these relations, indicating a high level of temporal and spatial variability in the PDF. Thus, the PDF of the mass density is unlikely to be a good measure of magnetic field strength. We also find that the PDF of decaying MHD turbulence deviates from the mean-Mach relation found in the driven case. This implies that the instantaneous Mach number alone is not enough to determine the statistical properties of turbulence that is out of equilibrium. The scatter about the mean-Mach relation for driven turbulence, along with the large departure of decaying turbulence PDFs from those of driven turbulence, may illuminate one factor contributing to the large observed cloud-to-cloud variation in the star formation rate per solar mass.
Longitudinal electron bunch diagnostics using coherent transition radiation

The longitudinal charge distribution of electron bunches in the Fermilab/NICADD photoinjector was determined using the coherent transition radiation produced by electrons passing through a thin metallic foil. The autocorrelation of the transition radiation signal was measured with a Michelson-type interferometer. The response function of the interferometer was determined from measured and simulated intensity spectra for low electron bunch charge and maximum longitudinal compression. Both pyroelectric and Golay detectors were used for these measurements. A Kramers-Kronig technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms). To test the accuracy of this interferometric method, the longitudinal charge distribution was measured for double-peaked electron bunches with known distance between the two pulses. The agreement between measured bunch length and simulation is within 30%.
Necrotizing genital ulcerations in a premenarcheal female with mononucleosis

Abstract Background: Two cases of genital ulcerations caused by Epstein-Barr virus have been reported previously, one in a sexually active 23-year-old and another in a 14-year-old practicing cunnilingus. Case: We report a case of Epstein-Barr virus genital ulcerations in a premenarcheal virgin. Her systemic symptoms were atypical for mononucleosis. Necrotizing genital ulcerations preceded pharyngitis and oral lesions. Cervical adenopathy, fever, and splenomegaly never developed despite serologic evidence of acute mononucleosis. Conclusion: Genital ulcerations can be the initial manifestation of Epstein-Barr virus in adolescents who are neither sexually active nor immunocompromised.
Theory of dielectric-filled edge-slot antennas

A theory has been developed for dielectric-filled edge-slot (DFES) antennas which belong to a class of circumferential slot antennas that are suitable for conformal mounting on conducting bodies of revolution. The specific antenna considered consists of a disk of dielectric substrate mounted between the two halves of a conducting cylinder and is excited at its center by a coaxial stub. It can be tuned for a desired operating frequency with the help of a number of axially oriented passive metallic posts located inside the dielectric region. For analysis, the antenna is modeled as a symmetrically excited E -type radial waveguide loaded with the metallic posts and terminated by an equivalent admittance appropriate for the radiating aperture. Circuit parameters for the metallic posts in the radial waveguide are obtained by detailed field analysis using mode matchng techniques. These are then used, along with the equivalent transmission line circuit for the antenna, to obtain the input reflection coefficient as a function of frequency for various DFES antennas. The results of computations based on the theory developed are compared with available measured values.
ProgME: towards programmable network measurement

Traffic measurements provide critical input for a wide range of network management applications, including traffic engineering, accounting, and security analysis. Existing measurement tools collect traffic statistics based on some predetermined, inflexible concept of "flows." They do not have sufficient built-in intelligence to understand the application requirements or adapt to the traffic conditions. Consequently, they have limited scalability with respect to the number of flows and the heterogeneity of monitoring applications. We present ProgME, a Programmable MEasurement architecture based on a novel concept of flowset--an arbitrary set of flows defined according to application requirements and/or traffic conditions. Through a simple flowset composition language, ProgME can incorporate application requirements, adapt itself to circumvent the scalability challenges posed by the large number of flows, and achieve a better application-perceived accuracy. The modular design of ProgME enables it to exploit the surging popularity of multicore processors to cope with 7-Gb/s line rate. ProgME can analyze and adapt to traffic statistics in real time. Using sequential hypothesis test, ProgME can achieve fast and scalable heavy hitter identification.
Hypercube computing: Connected components

Several approaches to finding the connected components of a graph on a hypercube multicomputer are proposed and analyzed. The results of experiments conducted on an NCUBE hypercube are also presented. The experimental results support the analysis.
Optimization of a Pd-catalyzed intramolecular α-arylation synthesis of tricyclo-[7.3.1.02,7]-trideca-2,4,6-trien-13-ones

We have optimized the Pd-catalyzed intramolecular α-arylation of 2-(2-halo-benzyl)-cyclohexanones and found that the use of 2-(dicyclohexylphosphino)-2′,4′,6′-tri-i-propyl-1,1′-biphenyl (X-Phos) as an added ligand led to a reproducible, efficient, and scalable synthesis of tricycle-[7.3.1.02,7]-trideca-2,4,6-trien-13-ones.
Visual working memory as the substrate for mental rotation

In mental rotation, a mental representation of an object must be rotated while the actual object remains visible. Where is this representation stored while it is being rotated? To answer this question, observers were asked to perform a mental rotation task during the delay interval of a visual working memory task. When the working memory task required the storage of object features, substantial bidirectional interference was observed between the memory and rotation tasks, and the interference increased with the degree of rotation. However, rotation-dependent interference was not observed when a spatial working memory task was used instead of an object working memory task. Thus, the object working memory subsystem—not the spatial working memory subsystem—provides the buffer in which object representations are stored while they undergo mental rotation. More broadly, the nature of the information being stored—not the nature of the operations performed on this information—may determine which subsystem stores the information.
Numerical Simulation of the Impingement of a Streamwise Vortex on a Plate

Abstract The flow field generated by the impingement of a della-wing vortex on a plate is examined computationally. The flow is simulated by solving the unsteady, three-dimensional Navier-Slokes equations on an overset grid system using a time accurate, implicit Beam and Warming algorithm. Comparison of the computed solutions for two levels of mesh resolution indicates that no additional flow features appear with grid refinement. Both the mean and unsteady flow structures are examined. Over the delta wing the (low exhibits a spiral vortex breakdown induced by the plate. Underneath the plate a highly unsteady, large-scale (owl-type) stall region is formed and results in the shedding of hairpin-like vortical structures. On the top surface of the plate a shallow separation region also exists outboard of the vortex impingement location. These separated flow features result from the spanwise variation in effective angle of attack created by the incoming vortex system. Also present over the upper surface is a m...
Binary switching in a ‘symmetric’ potential landscape

A binary switch is the basic building block for information processing. The potential energy profile of a bistable binary switch is a ‘symmetric’ double well. The traditional method of switching it from one state (one well) to the other is to tilt the profile towards the desired state. Here, we present a case, where no such tilting is necessary to switch successfully, even in the presence of thermal noise. This happens because of the built-in dynamics inside the switch itself. It differs from the general perception on binary switching that in a ‘symmetric’ potential landscape, the switching probability is 50% in the presence of thermal noise. Our results, considering the complete three-dimensional potential landscape, demonstrate intriguing phenomena on binary switching mechanism. With experimentally feasible parameters, we theoretically demonstrate such intriguing possibility in electric field induced magnetization switching of a shape-anisotropic single-domain magnetostrictive nanomagnet with two stable states at room-temperature.
A Bayesian Analysis Of The Unit Root Hypothesis Within An Unobserved Components Model

In this paper we extend some of Phillips's [4] results to nonlinear unobserved components models and develop a posterior odds ratio test of the unit root hypothesis based on flat and Jeffreys priors. In contrast to the analysis presented by Schotman and van Dijk [9], we utilize a nondegenerate structural representation of the components model that allows us to determine well-behaved Jeffreys priors, posterior densities under flat priors and Jeffreys priors, and posterior odds ratios for the unit root hypothesis without a proper prior for the level parameter. The analysis highlights the importance of the treatment of initial values for inference concerning stationarity and unit roots.
All‐optical logic performance of quantum‐dot semiconductor amplifier‐based devices

The performances of all-optical logic gates AND, OR, XOR, and NOT, based on quantum-dot semiconductor optical amplifier (QD-SOA) devices, are simulated. The saturation power, optical gain, and optical phase response of a QD-SOA is analyzed numerically using a rate-equation model of quantum dots embedded in a wetting layer. The calculated response is used to model the performance of the logic gates. The impact of the injection current and the input-signal power on the system's quality factor are studied. For the parameters used in this paper, all-optical logic gates using QD-SOA are capable of operating at speeds of ∼250 Gb/s. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 29–35, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21252
Heat transfer enhancement in channels with turbulence promoters

Repeated rib-roughness elements have been used in advanced turbine cooling designs to enhance the internal heat transfer. Often the ribs are perpendicular to the main flow direction so that they have an angle-of-attack of 90 degrees. The objective of this investigation was to determine the effect of rib angle-of-attack on the pressure drop and the average heat-transfer coefficients in the fully developed turbulent air flow in a square duct with two opposite rib-roughened walls for Reynolds numbers varied from 7,000 to 90,000. The rib height-to-equivalent diameter ratio was kept at a constant value of 0.063, the rib pitch-to-height ratio was varied from 10 to 20, and the rib angle-of-attack (alpha) was varied from 90 to 60 deg to 45 to 30 deg, respectively. The thermal-performance comparison indicated that the increased heat conductance for the rib with an oblique angle to the flow (alpha = 45 deg - 30 deg) was about 10-20 percent higher than the rib with a 90 deg angle to the flow, and the pumping power requirement for the angled rib was about 20-50 percent lower than the transverse rib. Semi-empirical correlations for friction factor and heat-transfer coefficients were developed to account for rib spacing and rib angle. The correlations can be used in the design of turbine-blade cooling passages.
Heat Transfer and Effectiveness on Film Cooled Turbine Blade Tip Models

It unshrouded axial turbine stages, a small but generally unavoilable clearance between the blade tips and the stationary outer seal allows a clearance gap leakage flow to be driven across the blade tip by the pressure-to-suction side pressure difference. In modern high-temperature machines, the turbine blade tips are often a region prone to early failure because of the presence of hot gases in the gap and the resultant added convection heating that must be counteracted by active blade cooling. The blade tip region, particularly near the trailing edge, is often very difficult to cool adequately with blade internal coolant flow, and film cooling injection directly onto the blade tip region can be used in an attempt to reduce the heat transfer rates directly from the hot clearance flow to the blade tip. An experimental program has been designed and conducted to model and measure the effects of film coolant injection of convection heat transfer to turbine blade tips. The modeling approach follows earlier work that found the leakage flow to be mainly a pressure-driven flow related strongly to the airfoil pressure loading distribution and only weakly, if at all, to the relative motion between blade tip and shroud. In the present work the clearance gap and blade tip region is thus modeled in stationary form with primary flow supplied to a narrow channel simulating the clearance gap above a plane blade tip. Secondary film flow is supplied to the tip surface through a line away of discrete normal injection holes near the upstream or pressure side. Both heat transfer and effectiveness are determined locally over the test surface downstream of injection through the use of this liquid crystal coatings and a computer vision system over an extensive test matrix of clearance heights, clearance flow Reynolds numbers, and film flow rates. The results of the study indicate that film injection near the pressure-side corner of plane turbine blade tips can provide significant protection from convection heat transfer to the tip from the hot clearance gap leakage flow
A Flexible Image Database System for Content-Based Retrieval

There is a growing need for the ability to query image databases based on similarity of image content rather than strict keyword search. As distance computations can be expensive, there is a need for indexing systems and algorithms that can eliminate candidate images without performing distance calculations. As user needs may change from session to session, there is also a need for run-time creation of distance measures. In this paper, we present FIDS, “flexible image database system.” FIDS allows the user to query the database based on complex combinations of dozens of predefined distance measures. Using an indexing scheme and algorithms based on the triangle inequality, FIDS can often return matches to the query image without directly comparing the query image to more than a small percentage of the database. This paper describes the technical contributions of the FIDS approach to content-based image retrieval.
Regioselective synthesis, X-ray structure, and reactivity of a tricyclic tetrasulfone, 1,3,5,7-tetramethyl-2,4,6,8,9,10-hexathiatricyclo[3.3.1.13,7]decane 2,2,4,4,6,6,8,8-octaoxide, derived from tetramethylhexathiaadamantane

Enthalpically disfavored tetrasulfone 9 is regioselectively synthesized from hexathiaadamantane 1; X-ray crystallographic data shows 9 to be compressed relative to 1 along its transannular S9–S10 through space axis containing sulfide functions; 9 exhibits diverse reactivity including thermal extrusion of SO2, further oxidation to pentasulfone 10, and transalkylation to tetradodecyl substituted tetrasulfone 11.
Kinetic target-guided synthesis

In the last decade, various target-guided synthesis (TGS) approaches have been developed in which a target protein is actively engaged in the assembly of its own bidentate ligand from a pool of smaller reactive fragments. Although TGS is relatively less explored, it demonstrates great promise to streamline drug discovery by combining screening and synthesis into a single step. Herein, we focus on the class of kinetic TGS approaches which utilize irreversible reactions to combine two reactive fragments into the inhibitory compound. These kinetic TGS applications have been successful due to the unique combination of the slow nature of the chemical reaction combining the two fragments into a single molecule and the use of reactive fragments displaying good affinities toward one of the binding sites. So far, kinetic TGS and especially in situ click chemistry, a kinetic TGS variant using the 1,3-dipolar cycloaddition of azides and alkynes, have led to the identification of highly potent inhibitors. This tutorial review focuses on kinetic TGS approaches aside from those employing the 1,3-dipolar cycloaddition of azides and alkynes, and discusses the features and advantages of these TGS approaches in detail.