cssi/SciSciGPT-SciSciNet huggingface dataset:
On the complexity of graph self-assembly in accretive systems

We study the complexity of the Accretive Graph Assembly Problem ( $${\tt{AGAP}}$$ ). An instance of $${\tt{AGAP}}$$ consists of an edge-weighted graph G, a seed vertex in G, and a temperature ?. The goal is to determine if the graph G can be assembled by a sequence of vertex additions starting from the seed vertex. The edge weights model the forces of attraction and repulsion, and determine which vertices can be added to a partially assembled graph at the given temperature. A vertex can be added when the total weight to its already built neighbors in the graph is at least ?. The assembly process is sequential meaning that only one vertex can be added at a time. Our first result is that $${\tt{AGAP}}$$ is NP-complete even on planar graphs with maximum degree 3 when edges have only two different types of weights. This resolves the complexity of $${\tt{AGAP}}$$ in the sense that the problem is poly-time solvable when either the maximum degree is at most 2 or the number of distinct edge weights is one, and is NP-complete otherwise. Our second result is a dichotomy theorem that completely characterizes the complexity of $${\tt{AGAP}}$$ on graphs with maximum degree 3 and two distinct weights: w p and w n . We give a simple system of linear constraints on w p , w n , and ? that determines whether the problem is NP-complete or is poly-time solvable. In the process of establishing this dichotomy, we give a poly-time algorithm to solve a non-trivial class of $${\tt{AGAP}}.$$ Finally, we consider the optimization version of $${\tt{AGAP}}$$ where the goal is to assemble a largest-possible induced subgraph of the given input graph. We show that even on graphs that can be assembled and have maximum degree 3, it is NP-hard to assemble a (1/n 1-?)-fraction of the input graph for any $$\varepsilon > 0;$$ here n denotes the number of vertices in G.
Prospects for a soft X-ray FEL powered by a Relativistic-Klystron High-Gradient Accelerator (RK-HGA)

Abstract We present here a conceptual design for an X-ray FEL operating at 45 A and producing 0.1–1.0 GW of power. Its architecture is a single-pass amplifier with growth from spontaneous noise. It uses an electron beam of about 1.5 GeV and with a normalized emittance of about 20 mm mrad, a beam which may be accelerated in a relatively short length of a high-gradient accelerator driven by an X-band relativistic klystron. Examination of sensitivity of the FEL performance to energy spread, wiggler field errors, jitter in the positioning of the electron beam, and finite steering accuracy indicates that the requisite technologies for this design are imminently available.
The impact of process mapping on transparency

Purpose – Process mapping is used to articulate the activities and procedures of business entities in a graphical way as pictorial images readily convey considerable information. The objective of this research is to provide evidence and a methodology to assist organizations in evaluating the early stages of their process mapping efforts.Design/methodology/approach – A review of literature identifies key characteristics of transparency (process visibility) related to process mapping. Quizzes and surveys are used to study the impact of process mapping on transparency in an employee training session.Findings – The paper finds that process mapping increases transparency between 5 percent and 27 percent for the applications discussed in this paper.Research limitations/implications – The research presumes that better understanding and recall of the company's business processes equates to higher transparency. This research study is limited to one field test, organization, and process mapping methodology. These l...
National Ignition Facility and managing location, component, and state

Abstract The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility that contains a 192-beam, 1.8-MJ, 500-TW, ultraviolet laser system coupled with a 10-m diameter target chamber. There are over 6200 Line Replaceable Units (LRUs) comprised of more than 104,000 serialized parts that make up the NIF. Each LRU is a modular unit typically composed of a mechanical housing, laser optics (glass, lenses, or mirrors), and utilities. To date, there are more than 120,000 data sets created to characterize the attributes of these parts. Greater than 51,000 Work Permits have been issued to install, maintain, and troubleshoot the components. One integrated system is used to manage these data, and more. The Location Component and State (LoCoS) system is a web application built using Java Enterprise Edition technologies and is accessed by over 1200 users. It is either directly or indirectly involved with each aspect of NIF work activity, and interfaces with ten external systems including the Integrated Computer Control System (ICCS) and the Laser Performance Operations Model (LPOM). Besides providing business functionality, LoCoS also acts as the NIF enterprise service bus. In this role, numerous integration approaches had to be adopted including: file exchange, database sharing, queuing, and web services in order to accommodate various business, technical, and security requirements. Architecture and implementation decisions are discussed.
Efficient synthesis of 2-(2′-hydroxyphenyl)benzoxazole by palladium(II)-catalyzed oxidative cyclization

Abstract An efficient method for the synthesis of 2-(2′-hydroxyphenyl)benzoxazole has been developed by using palladium-mediated oxidative cyclization.
Development and Testing of New Offshore Cathodic Protection Criteria

New sacrificial anode protection criteria developed and tested by Dubai Petroleum Co. (DPC) resulted in a 40% decrease in anode weight as compared to that required by conventionally accepted design. Derivation of the criteria is based on an analysis of extensive field results of potential surveys of seven DPC platforms that had conventional sacrificial anode protection systems. It was found that an initial platform current density of 29+.2 x 10/sup -3/A/sq ft (310+.20mA/m/sup 2/) of area exposed to seawater resulted in polarization of the platform to -1 V with respect to the silver/silver-chloride reference electrode. As a consequence of this initial polarization, the electric current requirement for protection is reduced significantly. The new criteria were used in the design of Platform JJ, which was installed in September 1982. Field results that include periodic potential surveys of Platform JJ are presented and discussed.
Transient Eddy Current in Magnet Structure Members

A computer program was developed to model transient eddy current in thin, connected plates. Eddy current is deduced from the solution of an equivalent-network problem. Loop currents are introduced by a transformation as the unknown variables of the network equations (Kirchoff's laws). The network equations are solved numerically by the Runge-Kutta method. This program is quite efficient, allows for holes and multiple materials, and has built-in rotational symmetry options. For cases with known solutions, the model has been checked for both spatial and temporal profiles of the eddy current. Results are given for eddy current profile and eddy current loss in the magnet case, support plate, and several other magnet structure members.
Industrial welfare and the state: nation and city reconsidered

Industrial welfare history presents important challenges to developmental state theories in “late” industrialization. This article expands the debate by examining how nation-states create statutory welfare by addressing institutional variety beyond markets. It is simplistic to argue linear growth of national welfare or of states autonomously regulating markets to achieve risk-mitigation. I contend that welfare institutions emerge from the state’s essential conflict and collaboration with various alternate institutions in cities and regions. Using histories of Europe, India, and Karnataka, I propose a place-based, work-based, and work-place based welfare typology evolving at differential rates. Although economic imperatives exist to expand local risk-pools, it is precisely the alternate institutional diversity that makes late industrial nation-states unable or unwilling to do so. This results in institutionally “thin,” top-down industrial welfare. Ultimately, theories that overly depend on histories of small nations, homogenous nations, or city-states, provide weak tests of the economics of industrial welfare.
Stability of networks and protocols in the adversarial queueing model for packet routing

The adversarial queueing theory model for packet routing was suggested by Borodin et al. We give a complete and simple characterization of all networks that are universally stable in this model. We show that the same characterization also holds for networks which are stable given that the packet forwarding protocol is FIFO (First in First out). We also show that a specific greedy protocol, SIS (Shortest in System), is stable against 0/1 stochastic adversaries. © 2001 John Wiley & Sons, Inc.
Semantic models for total correctness and fairness

Assertional s-rings are introduced to provide an algebraic setting in which the finite and infinite behavior of nondeterministic programs can be expressed and reasoned about. This includes expressing the fair infinite behavior of nondeterministic iterative programs, and reasoning about termination under various fairness assumptions. We also address the question of when the reasoning techniques are semantically complete.
Alveolar fluid clearance is faster in women with acute lung injury compared to men

Abstract Purpose Studies suggest that there is a sex difference in the development and outcomes of acute lung injury (ALI). Few studies have directly addressed the association of sex and alveolar fluid clearance (AFC), a process that is critical to ALI resolution. Materials and Methods To test the hypothesis that female sex is associated with an increased AFC rate, we measured AFC rates in 150 mechanically ventilated patients with acute pulmonary edema and a pulmonary edema fluid-to-plasma protein ratio (EF/PL) diagnostic of low permeability (EF/PL Results In patients with ALI, women had higher rates of net AFC at 4 hours compared to men (11.9% per hour vs 4.3% per hour, P = .017) and more women had maximal rates of AFC. There were no differences in circulating levels of receptor for advanced glycation end products between men and women. Conclusions These findings may have significant implications for future ALI studies and potential therapies.
Prospects for an Information-Technology-Led Productivity Surge

Information technology (IT) is enabling; without the invention of useful applications it is of little value. Some of the most valuable applications are themselves remarkable inventions. This means that advances in IT shift the invention-possibility frontier of the economy, permitting users of IT to invent new and sometimes highly valuable applications, rather than directly shifting the production-possibility frontier of the economy. IT is also general purpose technology, shared across a wide variety of uses. New advances in IT can therefore have an economy-wide impact, which will be larger or smaller according to the degree of sharing. Finally, IT has the possibility of substantial network effects. Together, these three features of IT mean that advances in it can have very substantial impacts on long-run growth. The pace of arrival of that growth varies across types of IT, however, according to the value of the enabled applications, the difficulty of the enabled invention (co-invention), the ease of shari...
A method for measuring the creep behavior of pressurized polymer tubing

Polymer components have been proposed for use in domestic solar hot-water heating systems. A polymer heat exchanger is under development for such systems. For heat transfer considerations, the heat exchanger will comprise many thin-walled tubes. The heat exchanger must survive 10 years of service at high pressure (1.55 MPa) and high temperature (82°C). A novel method has been developed for evaluating the long-term performance (creep) of the polymer tubing. Traditional creep testing, performed with dog bone test specimens, cannot be applied because the thin-walled tubing has anisotropic material properties. Consequently, performance must be evaluated directly on the extruded tubing. The method entails wrapping a Constantan wire around the tube specimen to continuously record the hoop strain. For pressure loading of tubing, this method offers significant improvements over strain gage instrumentation. In this paper, the test method is described, an analysis of the strain transfer between the tubing and wire wrap is presented, and strain data for polypropylene tubing measured with a strain gage and wire wrap are compared. The data show that the wire measurement method can be successfully used for the characterization of long-term mechanical behavior of polymer tubes.
Instituting a Monetary Economy in a Semester-Long Macroeconomics Course

The author provides a general model to incentivize student involvement in an economics course on an ongoing basis. Rather than presenting students with a discrete number of diverse experiments to illustrate different economic concepts, he opts for the adoption of a single experiment that lives for the duration of the semester. This approach provides the flexibility to illustrate a substantial number of concepts while forgoing some of the more in-depth analysis typically afforded by more traditional one-day experiments. By instituting an experimental unit of currency that takes on value throughout the semester, many concepts related, but not exclusive, to income, redistribution, intertemporal substitution, and banking can be reinforced with minimal loss of lecture time due to setup and rule exposition.
Supersymmetry and localization in the quantum Hall effect

Abstract We study the localization transition in the integer quantum Hall effect as described by the network model of quantum percolation. Starting from a path integral representation of transport Green functions for the network model, which employs both complex (bosonic) and Grassmann (fermionic) fields, we map the problem of localization to the problem of diagonalizing a one-dimensional non-hermitian Hamiltonian of interacting bosons and fermions. An exact solution is obtained in a restricted subspace of the Hilbert space which preserves boson-fermion supersymmetry. The physically relevant regime is investigated using the density matrix renormalization group (DMRG) method, and critical behavior is found at the plateau transition.
BlueBoX: A policy-driven, host-based intrusion detection system

Detecting attacks against systems has, in practice, largely been delegated to sensors, such as network intrustion detection systems. However, due to the inherent limitations of these systems and the increasing use of encryption in communication, intrusion detection and prevention have once again moved back to the host systems themselves. In this paper, we describe our experiences with building BlueBox, a host-based intrusion detection system. Our approach, based on the technique of system call introspection, can be viewed as creating an infrastructure for defining and enforcing very fine-grained process capabilities in the kernel. These capabilities are specified as a set of rules (policies) for regulating access to system resources on a per executable basis. The language for expressing the rules is intuitive and sufficiently expressive to effectively capture security boundaries.We have prototyped our approach on Linux operating system kernel and have built rule templates for popular daemons such as Apache and wu-ftpd. Our design has been validated by testing against a comprehensive database of known attacks. Our system has been designed to minimize the kernel changes and performance impact and thus can be ported easily to new kernels. We describe the motivation and rationale behind BlueBox, its design, implementation on Linux, and how it relates to prior work on detecting and preventing intrusions on host systems.
Intravenous administration of d-tubocurarine and pancuronium in fetal lambs

Summary The purpose of this study was to assess the effects of intravenous administration of d -tubocurarine and pancuronium in fetal lambs. Eighteen experiments were performed in seven chronically instrumented pregnant ewes between 0.8 and 0.9 of timed gestation. Each fetus received 6 ml of study drug intravenously at 1.2 ml/min over 5 minutes ( d -tubocurarine 3.0 mg/kg, pancuronium 0.5 mg/kg, or saline solution control). Pancuronium ( n = 7) significantly increased both fetal heart rate and mean arterial pressure. d -Tubocurarine ( n = 5) significantly decreased both fetal heart rate and mean arterial pressure. Saline solution control ( n = 6) did not significantly alter fetal heart rate or mean arterial pressure. The present study suggests that pancuronium is preferable to d -tubocurarine for those intrauterine procedures when an increase in fetal heart rate is desired. (Am J Obstet Gynecol 1989;160:510-3.)
Swimming by microscopic organisms in ambient water flow

When microscopic organisms swim in their natural habitats, they are simultaneously transported by ambient currents, waves, and turbulence. Therefore, to understand how swimming affects the movement of very small creatures through the environment, we need to study their behavior in realistic water flow conditions. The purpose of the work described here was to develop a series of integrated field and laboratory measurements at a variety of scales that enable us to record high-resolution videos of the behavior of microscopic organisms exposed to realistic spatio-temporal patterns of (1) water velocities and (2) distributions of chemical cues that affect their behavior. We have been developing these approaches while studying the swimming behavior in flowing water of the microscopic larvae of various bottom-dwelling marine animals. In shallow marine habitats, the oscillatory water motion associated with waves can make dramatic differences to water flow on the scales that affect trajectories of microscopic larvae.
The nonlinear analysis of self-field effects in free-electron lasers

Abstract A model of the DC self-fields associated with the electron beam is incorporated into 3-dimensional nonlinear formulations of free-electron lasers. The nonlinear formulations are based upon the ARACHNE and WIGGLIN codes which are slow-time-scale formulations for the evolution of the amplitudes and phases of a multi-mode superposition of vacuum waveguide modes. The electron dynamics in these codes are treated by means of the complete 3-dimensional Lorentz force equations, and the representations for the self-fields are incorporated directly into this formulation. Results of the simulations are compared with experiments at LLNL using a planar wiggler, and at MIT and NRL which used helical wigglers. These experiments exhibited comparable space-charge depressions of Δγ self γ 0 ≈ 0.53–0.78% across the beam. The simulations are in reasonable agreement with the experiments.
Numerical analysis of SSME preburner injector atomization and combustion processes

The coaxial spray injection and combustion flowfields of a Space Shuttle Main Engine preburner injector element have been analyzed using a three-phase numerical code. The processes of atomization, evaporation, secondary droplet breakup, and multispecies chemistry, as well as turbulent diffusion, are included. The model produced realistic pictures of the complex internal flowfield, including liquid jet length, spray shape, flame-zone size and characteristics, and predicted temperatures that seem to be in agreement with test data envelopes. It predicted an external group combustion type of flame. Salient combustion and mixing features are discussed and sources of uncertainty are pointed out for future studies.
A GRID OF RELATIVISTIC, NON-LTE ACCRETION DISK MODELS FOR SPECTRAL FITTING OF BLACK HOLE BINARIES

Self-consistent vertical structure models together with non-LTE radiative transfer should produce spectra from accretion disks around black holes, which differ from multitemperature blackbodies at levels that may be observed. High-resolution, high signal-to-noise observations warrant spectral modeling that both accounts for relativistic effects and treats the physics of radiative transfer in detail. In Davis et al. we presented spectral models that accounted for non-LTE effects, Compton scattering, and the opacities due to ions of abundant metals. Using a modification of this method, we have tabulated spectra for black hole masses typical of Galactic binaries. We make them publicly available for spectral fitting as an XSPEC model. These models represent the most complete realization of standard accretion disk theory to date. Thus, they are well suited both for testing the theory's applicability to observed systems and for constraining properties of the black holes, including their spins.
Elliptic models, type IIB orientifolds, and the AdS/CFT correspondence

Abstract We analyze the large N supergravity descriptions of the class of type IIB models T-dual to elliptic type IIA brane configurations containing two orientifold 6-planes and up to two NS 5-branes. The T-dual IIB configurations contain N D3-branes in the background of an orientifold 7-plane and, in some models, a Z 2 orbifold and/or D7-branes, which give rise to four-dimensional N =2 (or N =4 ) gauge theories with at most two factors. We identify the chiral primary states of the supergravity theories, and match them to gauge invariant operators of the corresponding superconformal theories using Maldacena's duality.
Synthesis of Aluminum Nitride/Boron Nitride Composite Materials

Aluminum nitride/boron nitride composite was synthesized by using boric acid, urea, and aluminum chloride (or aluminum lactate) as the starting compounds. The starting materials were dissolved in water and mixed homogeneously. Ammonolysis of this aqueous solution resulted in the formation of a precomposite gel, which converted into the aluminum nitride/boron nitride composite on further heat treatment. Characterization of both the precomposite and the composite powders included powder X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Analysis of the composite revealed that the aluminum nitride phase had a hexagonal structure, and the boron nitride phase a turbostratic structure.
Effects of high-latitude ionospheric electric field variability on global thermospheric Joule heating and mechanical energy transfer rate

[1] Effects of high-latitude ionospheric electric field variability on the Joule heating and mechanical energy transfer rate are investigated by incorporating realistic spatial and temporal characteristics of electric field variability derived from observations into the forcing of a thermosphere ionosphere electrodynamic general circulation model. First, the characteristics of subgrid-scale variability are examined from a spectral analysis of Dynamic Explorer-2 (DE-2) plasma drift measurements. The analysis reveals that the subgrid-scale electric field varies with magnetic latitude, magnetic local time, interplanetary magnetic field (IMF), and season in a manner distinct from that of the resolved-scale electric field and of the climatological electric field. The subgrid-scale electric field varies strongly with season, and its magnitude averaged over the polar region does not depend on IMF. On the other hand, the resolved-scale electric field depends less on season but more on IMF. Second, the spatial-temporal structure of resolved-scale electric fields are characterized from various electromagnetic observations taken during the storm period of January 10–11, 1997, using a space-time covariance model derived from the DE-2 observations. Finally, the modeling results show that the amount of Joule heating and mechanical energy transfer rate in the thermosphere is significantly altered by taking into account the electric field variability and its space-time structure. Additional electromagnetic energy due to the electric field variability dissipates in the ionosphere almost exclusively as Joule heating if the variability has no spatial and temporal correlation. However, the spatially and temporally correlated electric field variability has seasonally dependent effects on the mechanical energy transfer rate.
The X-Ray Surface Brightness Distribution from Diffuse Gas

We use simulations to predict the X-ray surface brightness distribution arising from hot, cosmologically distributed diffuse gas. The distribution is computed for two bands, 0.5-2 keV and 0.1-0.4 keV, using a cosmological-constant-dominated cosmology that fits many other observations. We examine a number of numerical issues such as resolution, simulation volume, and pixel size and show that the predicted mean background is sensitive to resolution such that higher resolution systematically increases the mean predicted background. Although this means that we can compute only lower bounds to the predicted level, these bounds are already quite restrictive. Since the observed extragalactic X-ray background is mostly accounted for by compact sources, the amount of the observed background attributable to diffuse gas is tightly constrained. We show that without physical processes in addition to those included in the simulations (such as radiative cooling or nongravitational heating), both bands exceed observational limits. In order to examine the effect of nongravitational heating we explore a simple model of energy injection and show that if this is the only mechanism operating to suppress the background then substantial amounts of heating would be required (i.e., 5 keV per particle when averaged over all baryons). Finally, we also compute the distribution of surface brightness on the sky and show that it has a well-resolved characteristic shape. This shape is substantially modified by nongravitational heating and can be used as a probe of such energy injection.
On Lazy Bin Covering and Packing problems

In this paper, we study two interesting variants of the classical bin packing problem, called Lazy Bin Covering (LBC) and Cardinality Constrained Maximum Resource Bin Packing (CCMRBP) problems. For the offline LBC problem, we first prove the approximation ratio of the First-Fit-Decreasing and First-Fit-Increasing algorithms, then present an APTAS. For the online LBC problem, we give a competitive analysis for the algorithms of Next-Fit, Worst-Fit, First-Fit, and a modified HARMONIC"M algorithm. The CCMRBP problem is a generalization of the Maximum Resource Bin Packing (MRBP) problem Boyar et al. (2006) [1]. For this problem, we prove that its offline version is no harder to approximate than the offline MRBP problem.
g -Elements of matroid complexes

A g-element for a graded R-module is a one-form with properties similar to a Lefschetz class in the cohomology ring of a compact complex projective manifold, except that the induced multiplication maps are injections instead of bijections. We show that if k(Δ) is the face ring of the independence complex of a matroid and the characteristic of k is zero, then there is a nonempty Zariski open subset of pairs (Θ, Ω) such that Θ is a linear set of parameters for k(Δ) and Ω is a g-element for k(Δ)/ 〈Θ〉. This leads to an inequality on the first half of the h-vector of the complex similar to the g-theorem for simplicial polytopes.
Behind the learning curve: a sketch of the learning process

This exploratory paper sketches some of the behavioral processes that give rise to the learning curve. Using data from two manufacturing departments in an electronic equipment company, we construct a model of productivity improvement as a function of cumulative output and two managerial variables-engineering changes and workforce training. Exploration of this model highlights the complex relationship between first-order and second-order learning.
Textured minimal and extended supergravity unification and implications for proton stability

Abstract We construct a class of textured supergravity unified SU(5) models using Planck scale corrections. We show that the texture constraints in the Higgs doublet sector are insufficient in general to fully determine the textures in the Higgs triplet sector. A classification of textured minimal parameter models is given and their Higgs triplet textures computed under the constraint that they possess the Georgi-Jarlskog textures in the Higgs doublet sector. It is argued that additional dynamical assumptions are needed to remove the ambiguity. The recently proposed extension of supergravity unification to include a minimal exotic sector is free of this ambiguity and leads to unique textures in the Higgs triplet sector. Implications for proton stability are discussed.
Optimal placement of convex polygons to maximize point containment

Given a convex polygon P with m vertices and a set S of n points in the plane, we consider the problem of finding a placement of P (allowing both translation and rotation) that contains the maximum number of points in S. We present first an algorithm requiring O(n^2km^2log(mn)) time and O(n + m) space, where k is the maximum number of points contained. We then give a refinement that makes use of bucketing to improve the running time to O(nk^2c^2m^2log(mk)), where c is the ratio of length to width of the polygon. This provides an improvement over the best previously known algorithm linear in n when k is large (@Q(n)) and a cubic when k is small. We also show that the algorithm can be extended to solve bichromatic and general weighted variants of the problem. The algorithm is self-contained and utilizes the geometric properties of the containing regions in the parameter space of transformations.
Applications of Tauberian Theorem for High-SNR Analysis of Performance over Fading Channels

This paper derives high-SNR asymptotic average error rates over fading channels by relating them to the outage probability, under mild assumptions. The analysis is based on the Tauberian theorem for Laplace-Stieltjes transforms which is grounded on the notion of regular variation, and applies to a wider range of channel distributions than existing approaches. The theory of regular variation is argued to be the proper mathematical framework for finding sufficient and necessary conditions for outage events to dominate high-SNR error rate performance. It is proved that the diversity order being d and the cumulative distribution function (CDF) of the channel power gain having variation exponent d at 0 imply each other, provided that the instantaneous error rate is upper-bounded by an exponential function of the instantaneous SNR. High-SNR asymptotic average error rates are derived for specific instantaneous error rates. Compared to existing approaches in the literature, the asymptotic expressions are related to the channel distribution in a much simpler manner herein, and related with outage more intuitively. The high-SNR asymptotic error rate is also characterized under diversity combining schemes with the channel power gain of each branch having a regularly varying CDF. Numerical results are shown to corroborate our theoretical analysis.
Synthesis and anticonvulsant activity of some novel 3-aminoquinazolines

A number of novel 3-aminoquinazolines were obtained via two synthetic pathways. In the first method o-aminobenzoylhydrazines were prepared either by reacting an isatoic anhydride and a hydrazine or by reacting o-nitrobenzoic acid with a hydrazine, followed by catalytic reduction. Subsequent cyclization with an appropriate orthoester provided 3-aminoquinazolines and 2-methyl-3-aminoquinazolines. The second pathway involved condensation of o-aminoacetophenone with a hydrazine to form hydrazones which were reduced to aminohydrazines and cyclized as above to yield 4-methyl-3-aminoquinazolines and 2,4-dimethyl-3-aminoquinazolines. The title compounds were evaluated in mice in MES and sc Met seizure models for anticonvulsant activity, and in the rotorod test for neurotoxicity. They were generally toxic. However, 4-methyl-3-(N-piperidino)-3,4-dihydroquinazoline hydrochloride exhibited activity comparable to that of methaqualone.
MACHOs, White Dwarfs, and the Age of the Universe

A favored interpretation of recent microlensing measurements toward the Large Magellanic Cloud implies that a large fraction (i.e., 10%-50%) of the mass of the Galactic dark halo is composed of white dwarfs. However, a ground-based search by Liebert and a recent search of the Hubble Deep Field by Flynn did not detect a substantial dark halo population of white dwarfs; thus the putative halo population is either dim enough or sparse enough to have eluded detection. In this paper we compare model white dwarf luminosity functions to the data from the observational surveys in order to determine a lower bound on the age of any substantial white dwarf halo population (and hence possibly on the age of the universe). In the course of our analysis we pay special attention to the velocity bias in the Liebert and coworkers, survey; we show that (and quantify by how much) the velocity bias renders the survey significantly less sensitive to a cool white dwarf population. We show that the minimum age of a white dwarf halo population depends most strongly on assumptions about three unknown quantities: (1) the white dwarfs' total space density, (2) their atmospheric composition, and (3) the initial mass function (IMF) of their progenitors. We compare various theoretical white dwarf luminosity functions, in which we vary these three parameters, with the abovementioned survey results. From this comparison, we conclude that if white dwarfs do indeed constitute more than 10% (30%) of the local halo mass density and are candidates for explaining the microlensing events, then the universe must be at least 10 Gyr old (12 Gyr old) for our most extreme allowed values of the parameters. When we use cooling curves that account for chemical fractionation and more likely values of the IMF and the bolometric correction, we find tighter limits; a white dwarf MACHO fraction of 10% (30%) requires a minimum age of 14 Gyr (15.5 Gyr). Our analysis also provides evidence that the halo white dwarfs have helium-dominated atmospheres, although this conclusion may change after low-temperature white dwarf atmospheres have been calculated.
Growth and fruit production of young micropropagated apple (Malus domestica Borkh.) trees

Abstract Tree size, cumulative yield, yield efficiency and anchorage of six micropropagated (MP) apple ( Malus domestica Borkh.) cultivars were determined in 1991 after 5 years of fruit production, as compared with trees budded on domestic seedling (sdlg) or Malling (M) 7a roots. Trees were planted in 1984, with crops harvested from 1987 through 1991. Trees of all scions except cultivar ‘Rome’ were smaller (as determined by trunk cross-sectional area) on M 7a than for MP trees. MP trees of cultivar ‘Delicious’, cultivar ‘Jonathan’, cultivar ‘Rome’ and cultivar ‘Spartan’ were larger than trees on sdlg, while the opposite occurred with ‘Golden Delicious’ (GD). Cumulative yield was affected by a scion × rootstock interaction, with few consistent trends in scion or rootstock effects. Yield efficiency was also affected by a scion × rootstock interaction. In 1991, cumulative yield efficiency on M 7a was superior to other rootstocks with all scions except GD, while the efficiency of sdlg and MP trees was statistically similar with all scions. In general, cumulative yield efficiency for M 7a was twice that for sdlg and MP trees. Nearly all trees leaned in response to prevailing westerly winds, with trees on sdlg generally more upright than MP or M 7a trees.
A UNIFIED CATALOG OF RADIO OBJECTS DETECTED BY NVSS, FIRST, WENSS, GB6, AND SDSS

We construct a catalog of radio sources detected by the Green Bank 6 cm survey GB6, Faint Images of the Radio Sky at Twenty cm (FIRST) and NRAO VLA Sky Survey (NVSS) (20 cm), and Westerbork Northern Sky Survey (WENSS) (92 cm) radio surveys, and the Sloan Digital Sky Survey (SDSS) optical survey. The 2.7 million entries in the publicly-available master catalog are comprised of the closest three FIRST to NVSS matches (within 30'') and vice versa, and unmatched sources from each survey. Entries are supplemented by data from the other radio and optical surveys, where available. All objects with even a small probability of physical association are included, such that catalog users can easily implement their own selection criteria for data analysis. We perform data analysis in the ~ 3000 deg2 region of sky where the surveys overlap, which contains 140,000 NVSS-FIRST sources, of which 64,000 are detected by WENSS and 12,000 by GB6. About one third of each sample is detected by the SDSS. An automated classification method based on 20 cm fluxes defines three radio morphology classes: complex, resolved, and compact. Radio color-magnitude-morphology diagrams for these classes show structure suggestive of strong underlying physical correlations. Complex and resolved sources tend to have a steep spectral slope (α ~ –0.8) that is nearly constant from 6 to 92 cm, while the compact class (unresolved on ~5'' scale by FIRST) contains a significant number of flat-spectrum (α ~ 0) sources. In the optically-detected sample, quasars dominate the flat-spectrum compact sources while steep-spectrum and resolved objects contain substantial numbers of both quasars and galaxies. Differential radio counts of quasars and galaxies are similar at bright flux levels (>100 mJy at 20 cm), while at fainter levels the quasar counts are significantly reduced below galaxy counts. The optically-undetected sample is strongly biased toward steep-spectrum sources. In samples of quasars and galaxies with SDSS spectra (2885 and 1288 respectively), we find that radio properties such as spectral slope, morphology, and radio loudness are correlated with optical color and luminosity.
Acid-catalyzed single-layer resists for ArF lithography

A positive-tone single-layer resist for use with 193-nm radiation has been developed. The system contains a terpolymer of methyl methacrylate, methacrylic acid, and t -butyl methacrylate, along with a photoacid generator. The chemically amplified deprotection of the t -butyl methacrylate into methacrylic acid increases the polarity of the resist and allows selective dissolution in metal-ion-free aqueous-base solutions. The resist sensitivity is less than 10 mJ/cm 2 , and its inherent resolution is better than 0.1 μm. These acrylate-based systems have the potential to be both lower in cost and have better environmental stability than the deep ultraviolet chemically amplified resists that use phenolic resins.
Comparison-Effects of Broadened Property Jet Fuels on Older and Modern J79 Combustors

Comparaison des effets de carburants pour propulseurs a reaction ayant des specifications plus larges avec les chambres de combustion J79 (ancienne et nouvelle conception)
Rotating frame zeugmatography.

The proton sensitivity obtainable at 5 MHz from a baby is sufficiently large to suggest the possibility of obtaining images with millimetre resolution in seconds. Such goals present difficulties; for example, the high quality factor of the receiving coil necessary for good sensitivity limits the receiver bandwidth and leads to long pulse recovery times, and large, rapidly switched field gradients require power engineering. Solutions to these problems are being pursued at the National Institutes of Health (N.I.H.), where a high speed imaging system is under construction. For example, bandwidth and recovery time problems may be resolved with the aid of a low noise preamplifier with imaginary gain and Miller feedback, large gradients may be generated with a magnet comprising two rotatable hemispherical windings and switching of gradients may be eliminated by performing zeugmatography in the rotating frame. It is upon this latter aspect of the design that the present article concentrates.
Model systems for cofactor activity. Biomimetic reduction of vitamin K by 1,3-propanedithiol

Vitamin K is reduced to vitamin KH2 by lipoate in biological systems. To provide a model system for this reaction, we have studied the in vitro reduction of vitamin K by 1,3- propanedithiol. This reaction occurs rapidly in dimethyl sulfoxide (DMSO) at 23°C, demonstrating the validity of this model system. © 1996 John Wiley & Sons, Inc.
Optical Detection and Manipulation of Single Molecules in Room-Temperature Solutions

With the tight focus of a gaussian laser beam, single molecules in solution at room temperature can be trapped and detected by observation of fluorescent pho- tons. The focus defines an ultrasmall probe volume on the order of 1 femtoliter, and the electric ficld gradient associ- ated with this focus enables an individual molecule to be trapped and manipulated.
A Study of the direct - fitting method for measurement of galaxy velocity dispersions

We have measured the central stellar velocity dispersions of 33 nearby spiral and elliptical galaxies, using a straightforward template-fitting algorithm operating in the pixel domain. The spectra, obtained with the Double Spectrograph at Palomar Observatory, cover both the Ca triplet and the Mg I b region, and we present a comparison of the velocity dispersion measurements from these two spectral regions. Model fits to the Ca triplet region generally yield good results, with little sensitivity to the choice of template star. In contrast, the Mg I b region is more sensitive to template mismatch and to details of the fitting procedure, such as the order of a polynomial used to match the continuum shape of the template to the object. As a consequence of the correlation of the [Mg/Fe] ratio with velocity dispersion, it is difficult to obtain a satisfactory model fit to the Mg I b lines and the surrounding Fe blends simultaneously, particularly for giant elliptical galaxies with large velocity dispersions. We demonstrate that if the metallicities of the galaxy and template star are not well matched, then direct template-fitting results are improved if the Mg I b lines themselves are excluded from the fit and the velocity dispersion is determined from the surrounding weaker lines.
The complete family of Arnoux–Yoccoz surfaces

The family of translation surfaces (X g , ω g ) constructed by Arnoux and Yoccoz from self-similar interval exchange maps encompasses one example from each genus g greater than or equal to 3. We triangulate these surfaces and deduce general properties they share. The surfaces (X g , ω g ) converge to a surface (X ∞, ω ∞) of infinite genus and finite area. We study the exchange on infinitely many intervals that arises from the vertical flow on (X ∞, ω ∞) and compute the affine group of (X ∞, ω ∞), which has an index 2 cyclic subgroup generated by a hyperbolic element.
On the Positive Mass Theorem for Manifolds with Corners

We study the positive mass theorem for certain non-smooth metrics following P. Miao’s work. Our approach is to smooth the metric using the Ricci flow. As well as improving some previous results on the behaviour of the ADM mass under the Ricci flow, we extend the analysis of the zero mass case to higher dimensions.
Microlensing surveys of M31 in the wide-field imaging era

The Andromeda galaxy (M31) is the closest large galaxy to the Milky Way, and thus it is an important laboratory for studying massive dark objects in galactic halos by gravitational microlensing. Such studies strongly complement the studies of the Milky Way halo using the Large and Small Magellanic Clouds. We consider the possibilities for microlensing surveys of M31 using the next generation of wide-field imaging telescopes with fields of view in the square-degree range. We consider proposals for such imagers both on the ground and in space. For concreteness, we specialize to the Supernova/Acceleration Probe proposal for a space telescope and the Large Synoptic Survey Telescope proposal for a ground-based telescope. We find that a modest space-based survey of 50 visits of 1 hr each is considerably better than current ground-based surveys covering 5 years. Crucially, systematic effects can be considerably better controlled with a space telescope because of both the infrared sensitivity and the angular resolution. To be competitive, 8 m class wide-field ground-based imagers must take exposures of several hundred seconds with several days' cadence.
Synthesis of diaryl ethers through the copper-promoted arylation of phenols with arylboronic acids. An expedient synthesis of thyroxine

Abstract Diaryl ethers are readily synthesized in high yield at room temperature through the copper(II)-promoted coupling of arylboronic acids and phenols. The reaction is tolerant of a wide range of substituents on both coupling partners. These reaction conditions permit the racemization-free arylation of phenolic amino acids, methodology that has been applied to an efficient synthesis of thyroxine.
Kirchhoff’s theorems in higher dimensions and Reidemeister torsion

Using ideas from algebraic topology and statistical mechanics, we generalize Kirchhoff's network and matrix-tree theorems to finite CW complexes of arbitrary dimension. As an application, we give a formula expressing Reidemeister torsion as an enumeration of higher dimensional spanning trees.
The (p,q) string tension in a warped deformed conifold

We find the tension spectrum of the bound states of p fundamental strings and q D-strings at the bottom of a warped deformed conifold. We show that it can be obtained from a D3-brane wrapping a 2-cycle that is stabilized by both electric and magnetic fluxes. Because the F-strings are ZM-charged with non-zero binding energy, binding can take place even if (p,q) are not coprime. Implications for cosmic strings are briefly discussed.
How beryllium proved successful on the Space Shuttle Orbiter

The paper discusses the design and material property requirements that led to selection of premium structural grades of beryllium for three primary areas of the Space Shuttle Orbiter: the crew module windshield retainers, spacers, and beams; the navigation base in the crew module; and the umbilical external tank doors in the aft fuselage. Beryllium was used for two primary reasons: it is light and stiff. There are 22 mechanically attached beryllium parts and 15 adhesive-bonded beryllium parts in each Orbiter. Special tooling and fabrication processes were developed. Fabrication of detailed components required special cutting and etching parameters to eliminate cutter-induced twinning of the grain structure. These methods and processes, as well as some of the problems encountered, are discussed in detail. The windshield components, which were fabricated from premium structural grades of hot-pressed beryllium, are the first structural applications successfully used in a man-rated, pressurized spacecraft.
Optimal Asset Allocation Over the Business Cycle

Utilizing a broadly diversified portfolio of nine equity and debt assets, we show our portfolio's in-sample Markowitz return/risk profile considerably improved by keying asset proportions to cyclical changes in economic activity. For comparative purposes, we use the same assets in a hypothetical buy-and-hold benchmark portfolio. We find the variance/covariance structure of our portfolio to be considerably altered by the phase of the business cycle, with the diversification benefits enjoyed during expansions substantially diluted during recessions. Thus, cyclical reallocation appears to be more important in maintaining Markowitz efficiency during recessions vis-a-vis expansions. In the latter case we find expansion reallocation producing a 3.53% increase in our portfolio's return-to-risk ratio (relative to a buy-and-hold position), while for recessions optimal reallocation leads to a 79.14% increase.