cssi/SciSciGPT-SciSciNet huggingface dataset:
The Equations of Motion of an Artificial Satellite in Nonsingular Variables

The equations of motion of an artificial satellite are given in nonsingular variables. Any term in the geopotential is considered as well as luni-solar perturbations up to an arbitrary power of r/r prime; r prime being the geocentric distance of the disturbing body. Resonances with tesseral harmonics and with the moon or sun are also considered. By neglecting the shadow effect, the disturbing function for solar radiation is also developed in nonsingular variables for the long periodic perturbations. Formulas are developed for implementation of the theory in actual computations.
Effective earth radius for refraction of radio waves at altitudes above 1 km

Atmospheric refractivity gradients are responsible for the bending of radio and microwave propagation paths such that the electromagnetic line-of-sight deviates from the geometrical line-of-sight. Such refraction effects must be accounted for when the performance of airborne surveillance radar systems is modeled. For propagation paths within 1 km of the earth's surface, the effective earth radius model is normally valid and commonly used. In the present work, a ray trace method for determination of propagation paths in a semi-empirical, stratified atmosphere is described. Results obtained from the ray trace model are employed to show that the effective earth radius method (EERM) can be used for approximate determinations of grazing angle, ground range and slant range for higher altitude paths. Effective earth radius scale factors are given as functions of transmitter altitude for selected values of surface refractivity.
Modeling Term Structures of Defaultable Bonds

This article presents convenient reduced-form models of the valuation of contingent claims subject to default risk, focusing on applications to the term structure of interest rates for corporate or sovereign bonds. Examples include the valuation of a credit-spread option. This article presents a new approach to modeling term structures of bonds and other contingent claims that are subject to default risk. As in previous “reduced-form” models, we treat default as an unpredictable event governed by a hazard-rate process. 1 Our approach is distinguished by the parameterization of losses at default in terms of the fractional reduction in market value that occurs at default. Specifically, we fix some contingent claim that, in the event of no default, pays X at time T . We take as given an arbitrage-free setting in which all securities are priced in terms of some short-rate process r and equivalent martingale measure Q [see Harrison and Kreps (1979) and Harrison and Pliska (1981)]. Under this “risk-neutral” probability measure, we letht denote the hazard rate for default at time t and let Lt denote the expected fractional loss in market value if default were to occur at time t , conditional
Catalysis by Amino Acid-Derived Tetracoordinate Complexes: Enantioselective Addition of Dialkylzincs to Aliphatic and Aromatic Aldehydes

Me2Zn and Et2Zn added to aromatic and aliphatic aldehydes in the presence of 3 mol % of 2. (S)-1-Phenylethanol (91% ee) and (S)-1-phenylpropanol (86% ee) were synthesized from benzaldehyde and (S)-1-furan-2-yl-1-propanol (86% ee) from 2-furaldehyde. Nonanal and 3-phenylpropanal provided (S)-3-undecanol (96% ee) and (S)-1-phenyl-3-pentanol (94% ee). A solid-phase variant was effective with reduced ee's (e.g., 86% ee → 79% ee) for (S)-1-phenylpropanol.
A SIMPLE PREPARATION OF 1-HYDROXYPYRENE

(1989). A SIMPLE PREPARATION OF 1-HYDROXYPYRENE. Organic Preparations and Procedures International: Vol. 21, No. 2, pp. 223-225.
Measuring the Effects of a Land Value Tax on Land Development

The objective of this research was to evaluate using land value tax as a potential policy tool to moderate sprawling development in Nashville, TN, the nation’s most sprawling metropolitan community with a population of one million or more. A land development model was used to evaluate the hypothesis that a land value tax encourages more development closer to areas of preexisting development than does the observed property tax scheme. For the median and lower and upper quartiles of empirical densities, results show that distances are shorter between areas of preexisting development and parcels predicted to be developed under a hypothetical land value tax policy than distances predicted under the observed tax scheme. This finding suggests that land value taxation could be used to design compact development strategies in Nashville, TN.
A Parametric Nonlinear Model of Term Structure Dynamics

Recent nonparametric estimation studies pioneered by Ait-Sahalia document that the diffusion of the short rate is similar to the parametric function, r[superscript 1.5], estimated by Chan et al., whereas the drift is substantially nonlinear in the short rate. These empirical properties call into question the efficacy of the existing affine term structure models and beg for alternative models which admit the observed behavior. This article presents such a model. Our model delivers closed-form solutions for bond prices and a concave relationship between the interest rate and the yields. We show that in empirical analyses, our model outperforms the one-factor affine models in both time-series as well as cross-sectional tests. Article published by Oxford University Press on behalf of the Society for Financial Studies in its journal, The Review of Financial Studies.
From Luttinger liquid to non-Abelian quantum Hall states

An elegant theoretical construction utilizing an array of coupled one-dimensional wires provides an alternative approach to understanding non-Abelian quantum Hall states.
Tropical Secant Varieties of Linear Spaces

In this paper we investigate tropical secant varieties of ordinary linear spaces. These correspond to the log-limit sets of ordinary toric varieties; we show that their interesting parts are combinatorially isomorphic to a certain natural subcomplex of the complex of regular subdivisions of a corresponding point set, and we display the range of behavior of this object. We also use this characterization to reformulate the question of determining Barvinok rank into a question regarding regular subdivisions of products of simplices.
Self-intersection, axial anomaly and the string picture of QCD

The leading, planar diagrams of the 1Nc expansion and the usual string description suggest that quarks propagate on the boundary of a two-dimensional world surface. We restrict the quarks to the boundary of the world surface by giving them infinitely large mass on the interior of the surface and zero mass on its boundary and show that in this picture the QCD θ-vacua can be represented by the self-intersection number (or equivalently by the first Chern number of the normal bundle) of the surface.
Skitters and jacks: interactive 3D positioning tools

Let scene composition be the precise placement of shapes relative to each other, using affine transformations. By this definition, the steps of scene composition are the selection of objects to be moved, the choice of transformation, and the specification of the parameters of the transformation. These parameters can be divided into two classes: anchors (such as an axis of rotation) and end conditions (such as a number of degrees to rotate). I discuss the advantages of using Cartesian coordinate frames to describe both kinds of parameters. Coordinate frames used in this way are called jacks. I also describe an interactive technique for placing jacks, using a three-dimensional cursor, called a skitter.
Factor VIII structure and function.

Factor VIII, a non-covalent heterodimer comprised of a heavy chain (A1-A2-B domains) and light chain (A3-C1-C2 domains), circulates as an inactive procofactor in complex with von Willebrand factor. Metal ions are critical to the integrity of factor VIII, with Cu and Ca ions stabilizing the heterodimer and generating the active conformation, respectively. Activation of factor VIII catalyzed by thrombin appears dependent upon interactions with both anion-binding exosites I and II, and converts the heterodimer to the active cofactor, factor VIIIa. This protein, comprised of A1, A2, and A3-C1-C2 subunits, is labile due to weak affinity of the A2 subunit. Association of factor VIIIa with factor IXa to form the intrinsic factor Xase complex is membrane-dependent and involves multiple inter-protein contacts that remain poorly characterized.This complex catalyzes the conversion of factor X to factor Xa, a reaction that is essential for the propagation phase of coagulation.The role of factor VIIIa in this complex is to increase the catalytic efficiency for factor Xa generation by several orders of magnitude. Mechanisms for the down-regulation of factor Xase focus upon inactivation of the cofactor and include dissociation of the A2 subunit as well as activated protein C-catalyzed proteolysis.
Issues in enzyme-based metal ion biosensing in complex media

In developing fluorescence-based biosensors for rapidly determining metal ions such as zinc or copper in complex media such as sea water, serum, cerebrospinal fluid, or the interior of a cell, several issues must be considered. Among these are the selectivity, sensitivity, ease of calibration, speed of response, reversibility, stability, and the ease of immobilization onto a solid substrate. While the first three have been dealt with in the design of our transducer molecule, apocarbonic anhydrase II, the others remain to be considered. In this paper we examine the stability of the apoprotein to storage at various temperatures and pHs with a view to establishing storage conditions and lifetimes in operating environments for sensor transducers. Similarly, we immobilized a storage conditions and lifetimes in operating environments for sensor transducers. Similarly, we immobilized a fluorescent-labeled apo-CA variant on quartz to determine its sped, sensitivity, and kinetics of response.
Photoemission study of quantum confinement by a finite barrier: Cu/Co(wedge)/Cu(100)

Quantum confinement is studied with angle-resolved photoemission for ultrathin Cu separated from the Cu(100) substrate by an epitaxial wedge of Co (0--11 A) that serves as a finite barrier. For 2 ML of Cu, the photoemission intensities of the Cu [ital sp] quantum-well (QW) state at 1.6 eV binding energy and the corresponding [ital d]-band-derived QW state at 2.4 eV increase rapidly with the thickness of the Co barrier and indicate stronger confinement of the [ital d] QW state than of the [ital sp] state. Implications for the magnetic coupling and magnetoresistance are discussed.
Recent Advances in the Study of Electrochemical Micromachining

The present paper reviews some fundamental aspects related to the understanding of the high rate anodic dissolution processes and their influence on thin film patterning by electrochemical micromachining. The role of convective mass transport and current distribution on the surface finish and shape evolution is discussed. Several examples of the applications of maskless and through-mask electrochemical micromachining are presented.
Multiprocessing on supercomputers for computational aerodynamics

Little use is made of multiple processors available on current supercomputers computers with a theoretical peak performance capability equal to 100 MFLOPS or more to improve turnaround time in computational aerodynamics. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, such improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. We apply the concept of mul tiple instructions and multiple data MIMD through multitasking via a strategy that requires relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-Fortran-Unix interface. The existing code is mapped without the need for devel oping a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor.
Directional Land Value Gradients

The standard urban model supports the concept of a constant land price gradient throughout the urban area. It is a reasonable conjecture that the land price gradient would vary with direction from the CBD. The variation in the gradient could be caused by a number of factors, but the idea that the land price gradient is flatter along radial transportation routes than in other directions is widely recognized even though there is little rigorous empirical work supporting this belief. This paper will examine the structure of urban land prices with a focus on the land price gradient as a function of the direction around the center of the city using a piecewise linear function. The added flexibility in the gradient estimate gained by this approach reveals a dramatically varying directional land price gradient.
Distribution of Circumstellar Disk Masses in the Young Cluster NGC 2024

We determine the distribution of circumstellar disk masses in the young (~0.3 Myr) cluster NGC 2024 by imaging a 25 × 25 region in 3 mm continuum emission to an rms noise level of ~0.75 mJy beam-1 with the Owens Valley Millimeter Array. The mosaic encompasses 147 K-band sources, as well as the molecular ridge seen previously in dust continuum emission. We detect 10 pointlike sources in 3 mm continuum emission above the level of 5 σ within the unit gain region of the mosaic. One of these sources corresponds to the near-IR source IRS 2, an early B-type star. Two other sources are tentatively associated with low-mass near-IR cluster members, and the remaining seven sources have no K-band counterparts. Assuming the millimeter continuum point sources represent emission from circumstellar disks and/or envelopes, then ~6% of the total population (infrared and millimeter sources) in the NGC 2024 mosaic have a circumstellar mass in excess of ~0.06 M☉. We obtain further constraints on the average circumstellar disk mass by considering the mean millimeter continuum flux observed toward a sample of 140 K-band sources that likely have stellar masses 1-2 M☉. While none of these sources are detected individually above the 3 σ limit of ~0.035 M☉, the ensemble of sources are detected in the mean at the 5 σ level with a mean disk mass of ~0.005 M☉. Compared with the older (~2 Myr) cluster IC 348, NGC 2024 contains a higher frequency of massive disks or envelopes and has a higher mean disk mass by a factor of 2.5 ± 1.3 among K-band sources, suggesting that the mean circumstellar mass is decreasing with cluster age. We also compare the results for the NGC 2024 and IC 348 clusters with those for the lower density Taurus star-forming region. Finally, we compare our detection limits with the minimum mass estimate for the proto-solar nebula and discuss possible implications for planet formation.
Defect particle kinematics in one-dimensional cellular automata

Let A^Z be the Cantor space of bi-infinite sequences in a finite alphabet A, and let @s be the shift map on A^Z. A cellular automaton is a continuous, @s-commuting self-map @F of A^Z, and a @F-invariant subshift is a closed, (@F,@s)-invariant subset S@?A^Z. Suppose a@?A^Z is S-admissible everywhere except for some small region we call a defect. It has been empirically observed that such defects persist under iteration of @F, and often propagate like 'particles'. We characterize the motion of these particles, and show that it falls into several regimes, ranging from simple deterministic motion, to generalized random walks, to complex motion emulating Turing machines or pushdown automata. One consequence is that some questions about defect behaviour are formally undecidable.
A source model for predicting the drag force on a moving arc column.

A source model is proposed to describe the behavior of an arc column in a crossflow. The drag force on the arc column is found to be D = qUm/cpTm^ where q = joule heating per unit length, C/oo = freestream velocity, cp = specific heat, and Too = freestream temperature. When the drag force is balanced by a Lorentz force arising from an externally imposed magnetic field, the source model yields a relationship between crossflow Mach number and magnetic field which is in good agreement with experimental data for M^ < 0.3.
The Structure of Causal Sets

More often than not, recently popular structuralist interpretations of physical theories leave the central concept of a structure insufficiently precisified. The incipient causal sets approach to quantum gravity offers a paradigmatic case of a physical theory predestined to be interpreted in structuralist terms. It is shown how employing structuralism lends itself to a natural interpretation of the physical meaning of causal set theory. Conversely, the conceptually exceptionally clear case of causal sets is used as a foil to illustrate how a mathematically informed rigorous conceptualization of structure serves to identify structures in physical theories. Furthermore, a number of technical issues infesting structuralist interpretations of physical theories such as difficulties with grounding the identity of the places of highly symmetrical physical structures in their relational profile and what may resolve these difficulties can be vividly illustrated with causal sets.
Durable goods and residential demand for energy and water: evidence from a field trial

This article describes a household production model in which energy-efficient durable goods cost less to operate so households may use them more. The model is estimated using household-level data from a field trial in which participants received high-efficiency clothes washers free of charge. The estimation strategy exploits this quasi-random replacement of washers to derive precise estimates of the household production technology and a demand function for clothes washing. During the field trial, households increased clothes washing on average by 5.6% after receiving a high-efficiency washer, implying a price elasticity of −.06. The complete model is used to evaluate the cost-effectiveness of recent changes in minimum efficiency standards for clothes washers.
Media Tilt Tolerance of Bit-based and Page-based Holographic Storage Systems

Under a constraint of the same diffraction efficiency per pixel/detector and media dynamic range, a bit-based holographic storage has a larger media tilt tolerance compared to a page-based system with relatively large page size
A hyperbolic surface with a square grid net

We prove the existence of a hyperbolic surface spread over the sphere for which the projection map has all its singular values on the extended real line and such that the preimage of the extended real line under the projection map is homeomorphic to the square grid in the plane. This answers a question raised by E. B. Vinberg.
Optimal Aeroassisted Orbital Interception

Optimal trajectories are found for the interception of a target in circular, low Earth orbit, by a vehicle that is initially in a higher orbit. The interceptor vehicle can use both conventional rocket propulsion and, if optimal or necessary, aerodynamic forces to change its orbit. The problem is solved using a direct method, collocation with nonlinearprogramming,inwhich the continuousoptimalcontrolproblem is converted intoa discrete problem.Both minimum-timeandminimum-fueltrajectories are found.The sensitivity of the optimal trajectories to atmospheric heating-rate constraints is determined. An interesting result is that some minimum-time trajectories enter the atmosphere and use aerodynamic forces for orbit change even when there is suf cient propellant available to accomplish the interception ballistically.
How close are pth powers in the Nottingham group

Abstract Let F be a field of characteristic p > 0 and let f , g be elements of the Nottingham group N ( F ) such that f has depth k and g f −1 has depth n ⩾ k . We find the best possible lower bound for the depth of g p f − p .
Spitzer Far-Infrared Detections of Cold Circumstellar Disks

Observations at 70 ?m with the Spitzer Space Telescope have detected several stellar systems within 65 pc of the Sun. Of 18 presumably young systems detected in this study, as many as 15 have 70 ?m emission in excess of that expected from their stellar photospheres. Five of the systems with excesses are members of the Tucanae association. The 70 ?m excesses range from a factor of ~2 to nearly 30 times the expected photospheric emission from these stars. In contrast to the 70 ?m properties of these systems, there is evidence for an emission excess at 24 ?m for only HD 3003, confirming previous results for this star. The lack of a strong 24 ?m excess in most of these systems suggests that the circumstellar dust producing the IR excesses is relatively cool (Tdust 150 K) and that there is little IR-emitting material within the inner few AU of the primary stars. Many of these systems lie close enough to Earth that the distribution of the dust producing the IR excesses might be imaged in scattered light at optical and near-IR wavelengths.
Measurement and specification of the envelope correlation between two narrow bands of noise

Empirical measurements show that when two independent, narrow-band, Gaussian noises are 'mixed' or combined according to the method specified by Licklider and Dzendolet (1948) [Science, 107, 121-124], the correlation coefficient between the envelopes (rExy) of the two resulting narrow-band noises is approximately equal to the square of the correlation between the waveforms (rxy). This relation also holds for waveform correlations produced by de-correlating two perfectly correlated noises by the addition of a sinusoid (at the center frequency) that is phase-reversed (N0S pi). This is true so long as the signal-to-noise ratio is small. A method is detailed whereby any desired rExy may be achieved with reasonable accuracy between two noises of the same or different center-frequency. This method may prove particularly useful in the study of listeners' sensitivities to dissimilarities in the envelope fluctuation of bands of noise occupying discrete spectral loci, a topic currently of interest. It is hoped that the empirical relations between rxy and rExy may stimulate efforts to derive or locate analytic expressions that relate the two.
Instability of elliptic jets

This paper presents a detailed account of the hydrodynamic stability characteristics of the initial mixing region of an elliptic jet. A realistic mean velocity profile is used. Calculations of growth rates, phase velocities and eigenfunctions are presented. The growth rates of all modes in the initial mixing region scale with the minimum momentum thickness. Pressure fluctuations are found to be greatest for all modes close to the major axis. An irregular normal mode is found at larger eccentricities. The flapping mode about the major axis becomes the least stable as the momentum thickness of the mixing layer increases.
Ion-beam analysis of meteoritic and lunar samples

The unambiguity with which some nuclear reactions may be identified often permits their use as highly sensitive and selective analytical tools for the determination of trace element concentrations in complex materials. In this report examples are given of the use of charged particle-induced nuclear reactions in attacking particular problems in astrophysics and planetary science. These problems include the determination of elemental abundances of boron and flourine in carbonaceous chondritic meteorites, the identification of products of lunar vulcanism, and the study of solar wind-implanted atoms in lunar materials. This technique will be seen to be an important supplement to other methods of elemental and isotopic analysis — especially for cases involving light elements at very low concentrations and where high resolution depth distribution information is needed in non-destructive analyses.
Pulsar disk systems

It is proposed that radio pulsars have the same basic physical features as X-ray pulsars. Specifically, it is suggested that active radio pulsars are rotating neutron stars surrounded by fossil disks left over from the collapse event and that energy is extracted from the rotation of the neutron star by interaction with the disk to produce pulsar luminosity. Attention is given to a model in which the neutron star acts as a unipolar generator (or Faraday disk dynamo) and the disk acts as a load. The self-excitation of the disk/pulsar system is considered along with aspects of disk persistence, pulsed emission, and magnetically field aligned currents to the disk. An investigation is conducted regarding the possibility of a deposition of material in the form of a disk about a pulsar, taking into account questions concerning disk survival. It is found that there are some promising features regarding a disk system.
Micelle Formation and the Hydrophobic Effect

The tendency of amphiphilic molecules to form micelles in aqueous solution is a consequence of the hydrophobic effect. The fundamental difference between micelle assembly and macroscopic phase separation is the stoichiometric constraint that frustrates the demixing of polar and hydrophobic groups. We present a theory for micelle assembly that combines the account of this constraint with a description of the hydrophobic driving force. The latter arises from the length scale dependence of aqueous solvation. The theoretical predictions for temperature dependence and surfactant chain length dependence of critical micelle concentrations for nonionic surfactants agree favorably with experiment.
On the Dependence of the Iron K-Line Profiles with Luminosity in Active Galactic Nuclei

We present evidence for changes in the strength and profile of the iron Kα line in active galactic nuclei (AGNs), based on X-ray observations with ASCA. There is a clear decrease in the strength of the line with increasing luminosity. This relation is not due solely to radio power, as it persists when only radio-quiet AGNs are considered and therefore cannot be fully explained by relativistic beaming. In addition to the change in strength, the line profile also appears to be different in higher luminosity sources. We discuss these results in terms of a model where the accretion disk becomes ionized as a function of the accretion rate.
Streaming birefringence as a rheological research tool

Abstract This paper reviews theoretical and experimental evidence currently available to establish criteria “to aid the experimenter who wishes to use streaming birefringence as a tool for studying fluid flow. Instrumental techniques are reviewed, and the possibilities for both qualitative and quantitative flow visualization by streaming birefringence in pure Newtonian liquids, colloidal suspensions, and dilute and concentrated polymer solutions are discussed. Methods of reconstruction of the velocity and stress fields from birefringence data are outlined.
A practical route to substituted 7-aminoindoles from pyrrole-3-carboxaldehydes.

Among privileged structures, indoles occupy a central place in medicinal chemistry and alkaloid research. Here we report a flexible and efficient conversion of pyrrole-3-carboxaldehydes to substituted 7-amino-5-cyanoindoles. Phosphine addition to fumaronitrile proceeds with prototropic rearrangement of the initially formed zwitterion to the thermodynamically favored phosphonium ylide, which is poised for in situ Wittig olefination. The predominantly E-alkene product positions the allylic nitrile for facile intramolecular Hoeben–Hoesch reaction in the presence of BF3·OEt2. Syntheses of 2,5- and 3,5-disubstituted 7-aminoindoles are illustrated. Additionally, dianion alkylation of the allylic nitrile is demonstrated to furnish, after cyclization, 5,6-disubstituted 7-aminoindoles to further exemplify this scalable and high-yielding method.
MODEL-DRIVEN VISION USING PROCEDURE DESCRIPTION - MOTIVATION AND APPLICATION TO PHOTOINTERPRETATION AND MEDICAL DIAGNOSIS.

We present a general scheme for the representation and use of procedural knowledge in an image understanding system. Each procedure has associated with it a procedure descriptor, which characterizes the procedure's capabilities in terms of its input/output behavior and its performance characteristics. A general control paradigm, based on descriptor-directed invocation of procedures, is presented and shown to allow for: intelligent, goal-directed invocation; dynamic planning using local context; modular addition and change of procedural knowledge; and flexible allocation of computing resources. The representation scheme and control paradigm are being applied in the domains Of medical imagery (ultrasonograms and radiographs) and aerial imagery (of industrial sites).
A synthesis of α-amino acids via direct reductive carboxylation of imines with carbon dioxide

A method for the synthesis of α-amino acids by direct reductive carboxylation of aromatic imines with CO2 is described. The protocol employs readily available commercial reagents and serves as a one-step alternative to the Strecker synthesis.
The Numerical Simulation of a High-Speed Axial Flow Compressor

The advancement of high-speed axial-flow multistage compressors is impeded by a lack of detailed flow-field information. Recent development in compressor flow modeling and numerical simulation have the potential to provide needed information in a timely manner. The development of a computer program is described to solve the viscous form of the average-passage equation system for multistage turbomachinery. Programming issues such as in-core versus out-of-core data storage and CPU utilization (parallelization, vectorization, and chaining) are addressed. Code performance is evaluated through the simulation of the first four stages of a five-stage, high-speed, axial-flow compressor. The second part addresses the flow physics which can be obtained from the numerical simulation. In particular, an examination of the endwall flow structure is made, and its impact on blockage distribution assessed.
Challenges related to the composition of functional foods

Abstract There is a growing interest among producers and the public in functional foods or foods that may provide health benefits beyond basic nutrition. The availability of such foods highlights the changing nature of the food supply and the tremendous difficulty in trying to maintain accurate and timely food composition data. Key questions arise. How can and should we track and maintain a database of functional foods? What food components should we be measuring in order to meet the needs of users of the nutrient data? Do analytical techniques exist for some of these components and what effects do these components have on the measurement of other nutrients? We need to begin how to answer these and similar questions and the answers may vary depending on the nature of the variety of functional foods produced.
Cosmic ray neutron studies

Abstract : This report presents a study of the neutrons generated by the cosmic radiation. A series of balloon flights were made, in which the neutrons in the energy range between one and ten Mevs were measured, throughout the atmosphere. These flights were made from various stations, over a range of latitudes from near equatorial to near polar, and in time over several years. It was found that a large variation with solar activity exists, especially at the near-polar locations where the lowest-energy part of the incoming radiation is observable. The numbers of neutrons going into radiocarbon were calculated for various epochs as were the numbers escaping from the top of the atmosphere. The importance of studying the production of other isotopes including especially beryllium ten is stressed. Various solar acceleration mechanisms were also examined, with especial reference to those which on infrequent occasions inject spectacularly large amounts of radiation into the space surrounding the earth. (Author)
The QT interval following carotid artery resection

Background. Right radical neck dissection has been shown to prolong the QT interval, reportedly caused by surgical trauma to the cervical autonomic system, which may result in malignant ventricular arrhythmias. Carotid artery resection would be expected to be more likely to cause dangerous arrhythmias. Methods. We prospectively studied eight patients with electrocardiograms before and after carotid resection. Four patients had left-sided procedures and four patients had right-sided procedures. In addition, 11 patients were studied retrospectively. QT intervals were normal in all patients preoperatively. Results. Preoperative corrected QT intervals (QTc) were in the normal range used by our institution for all eight patients in the prospective group. There were no significant QTc changes after either left-sided or right-sided carotid resection. However, the retrospective group did show significant changes in QTc following right carotid resection (n = 5), but not left resection (n = 6). Conclusions. EKG changes associated with carotid resection may not be uniform and may depend on surgical technique or specific anatomic factors. Controlled prospective studies are needed to confirm the prevalence of QT interval changes in radical neck surgery.
An Empirical Analysis of the Decline in the Information Content of Earnings Following Restatements

Regulatory officials and market analysts have speculated that the loss of credibility in subsequently reported financial information is a long‐lasting consequence of earnings restatements. I measure the information content of earnings using a standard earnings‐returns framework over several years surrounding restatements to examine characteristics of the decline in the information content of earnings. Results indicate that although the information content of earnings declines following restatements, the loss is temporary. In particular, the earnings response coefficients for earnings announcements surrounding restatements exhibit a U‐shaped pattern in which they are no longer significantly lower in the post‐restatement period over an average of four quarters. The extent to which the earnings of restatement firms suffer a loss of information content varies across several dimensions. First, the duration of the loss is greater for firms that restate earnings to correct revenue recognition errors and for rest...
Demand, Information, and Competition: Why Do Food Prices Fall at Seasonal Demand Peaks?

Prices for seasonal food products fall at demand peaks. Price declines are not driven by falling agricultural input prices; indeed, farm to retail margins narrow sharply. I use electronic scanner data from a sample of US supermarkets to show that seasonal price declines are closely linked to market concentration, and are much larger in markets with several rivals than where a single brand dominates. Seasonal demand increases reduce the effective costs of informative advertising, and increased informative advertising by retailers and manufacturers in turn may allow for increased market information and greater price sensitivity on the part of buyers.
The stationary Maxwell–Dirac equations

The Maxwell–Dirac equations are the equations for electronic matter, the 'classical' theory underlying QED. The system combines the Dirac equations with the Maxwell equations sourced by the Dirac current. A stationary Maxwell–Dirac system has ψ = e−iEt, with independent of t. The system is said to be isolated if the dependent variables obey quite weak regularity and decay conditions. In this paper, we prove the following strong localization result for isolated, stationary Maxwell–Dirac systems, there are no embedded eigenvalues in the essential spectrum, i.e. −m ≤ E ≤ m; if |E| < m then the Dirac field decays exponentially as |x| → ∞; if |E| = m then the system is 'asymptotically' static and decays exponentially if the total charge is non-zero.
Molecular Structure and Photochemistry of (E)- and (Z)-Ethyl 3-(2-Indolyl)propenoate. Ground State Conformational Control of Photochemical Behavior and One-Way E → Z Photoisomerization

The molecular structure, electronic spectra, and photoisomerization of (E)- and (Z)-ethyl 3-(2-indolyl)propenoate, two methylated indole derivatives, and their N,N-dimethylamide analog have been investigated. The E ester exists in the ground state as a mixture of anti and syn rotational isomers. The spectroscopic and photochemical behaviors of the individual anti and syn conformers were characterized with the assistance of comparisons with the behavior of the methylated indole derivatives. The major anti conformer of the E ester absorbs and emits at shorter wavelength than the minor syn conformer. The rate constant for singlet state isomerization of the anti conformer is substantially larger than that of the syn conformer, resulting in a shorter singlet lifetime and smaller fluorescence quantum yield for the anti conformer. The behavior of the E amide in both the ground and excited states is similar to that of the ester. The Z isomers of the ester and amide possess a relatively strong intramolecular hydro...
On uniform circuit complexity

Abstract We argue that uniform circuit complexity introduced by Borodin is a reasonable model of parallel complexity. Three main results are presented. First, we show that alternating Turing machines are also a surprisingly good model of parallel complexity, by showing that simultaneous size/depth of uniform circuits is the same as space/time of alternating Turing machines, with depth and time within a constant factor and likewise log(size) and space. Second, we apply this to characterize NC, the class of polynomial size and polynomial-in-log depth circuits, in terms of tree-size bounded alternating TMs and other models. In particular, this enables us to show that context-free language recognition is in NC. Third, we investigate various definitions of uniform circuit complexity, showing that it is fairly insensitive to the choice of definition.
Predictors of nursing home admission, severe functional impairment, or death one year after surgery for non-small cell lung cancer.

OBJECTIVE To assess factors associated with nursing home admission, severe functional impairment, or death 1 year after surgery for stage I-IIIa non-small cell lung cancer. BACKGROUND Patients perceive long-term disability to be one of the most undesirable complications of lung cancer treatment. METHODS A multiregional cohort was surveyed 12 months after surgery. Logistic regression was used to determine adjusted predictors of long-term disability. Recursive partitioning was used to create a risk index based on preoperative factors. RESULTS Of the 1007 patients, 146 (15%) were admitted to a nursing home or died by 1 year after surgery, with higher risk among patients 80 years or older, those with severe comorbidities, and those with stage II-IIIa disease (all Ps ≤ 0.01). Among 759 survivors who completed the follow-up survey, 51 (7%) were admitted to a nursing home or reported inability to get out of bed, dress or wash themselves, or perform usual activities. Patients with moderate comorbidities (P < 0.001) or lack of high school diploma (P = 0.03) were more likely to experience nursing home admission or severe functional impairment. The risk of nursing home admission, severe functional impairment, or death was low (16%) for patients younger than 75 years and for those 75 years or older with stage I disease, intermediate (33%) for patients 75 years or older with stage II-IIIa disease and no or mild comorbidities, and high (60%) for those 75 years or older with stage II-IIIa disease and moderate or severe comorbidities. CONCLUSIONS Patients' risk of long-term disability should be incorporated in preoperative counseling.
Calibrated thermal microscopy of the tool-chip interface in machining

A critical parameter in predicting tool wear during machining and in accurate computer simulations of machining is the spatially-resolved temperature at the tool-chip interface. We describe the development and the calibration of a nearly diffraction-limited thermal-imaging microscope to measure the spatially-resolved temperatures during the machining of an AISI 1045 steel with a tungsten-carbide tool bit. The microscope has a target area of 0.5 mm X 0.5 mm square region with a < 5 micrometers spatial resolution and is based on a commercial InSb 128 X 128 focal plane array with an all reflective microscope objective. The minimum frame image acquisition time is < 1 ms. The microscope is calibrated using a standard blackbody source from the radiance temperature calibration laboratory at the National Institute of Standards and Technology, and the emissivity of the machined material is deduced from the infrared reflectivity measurements. The steady-state thermal images from the machining of 1045 steel are compared to previous determinations of tool temperatures from micro-hardness measurements and are found to be in agreement with those studies. The measured average chip temperatures are also in agreement with the temperature rise estimated from energy balance considerations. From these calculations and the agreement between the experimental and the calculated determinations of the emissivity of the 1045 steel, the standard uncertainty of the temperature measurements is estimated to be about 45 degree(s)C at 900 degree(s)C.
Effect of changes in ozone amount on the ultraviolet radiation received at sea level of a model atmosphere

Abstract Results of numerical simulation of the spectral distribution of the direct solar energy and diffuse skylight energy incident upon a horizontal flat surface located at the bottom of a one-dimensional atmospheric model are presented as a function of four different parameters, viz. wavelength (0.2975-0.375 μm), solar zenith angle (0°–80°), Lambert reflectivity of the underlying surface (0.0, 0.3), and ozone amount (0.200-0.450 atm-cm). These computations were carried out after taking into account all orders of scattering and appropriate absorption by molecules and aerosols. The height distributions of ozone and aerosol particles used in these models correspond to those observed in the mid-latitude region. A given decrease in the atmospheric ozone content results in a strong increase in the direct component, but in a relatively moderate increase in the diffuse component. Furthermore, variations in the changes in the diffuse component with ozone amount show some interesting features which are not present in the corresponding variations for the direct component.
Parton saturation at small x and in large nuclei

Abstract Quark and gluon distributions in the light-cone wavefunction of a high energy hadron or nucleus are calculated in the saturation regime. One loop calculations are performed explicitly using the equivalence between the parton distribution in the light-cone wavefunction and the production distribution of that parton in a current-nucleon (nucleus) scattering. We argue that, except for some overall numerical factors, the Weizsacker-Williams wavefunction correctly gives the physics of the gluon distribution in a light-cone wavefunction.
Finite Element Model Update via Bayesian Estimation and Minimization of Dynamic Residuals

An algorithm is presented for updating finite element models based upon a minimization of dynamic residuals. The dynamic residual of interest is the force unbalance in the homogeneous form of the equations of motion arising from errors in the model`s mass and stiffness when evaluated with the identified modal parameters. The present algorithm is a modification and extension of a previously-developed Sensitivity-Based Element-By-Element (SB-EBE) method for damage detection and finite element model up- dating. In the present algorithm, SB-EBE has been generalized to minimize a dynamic displacement residual quantity, which is shown to improve test- analysis mode correspondence. Furthermore, the algorithm has been modified to include Bayesian estimation concepts, and the underlying nonlinear optimization problem has been consistently linearized to improve the convergence properties. The resulting algorithm is demonstrated via numerical and experimental examples to be an efficient and robust method for both localizing model errors and estimating physical parameters.
The Vidboard: a video capture and processing peripheral for a distributed multimedia system

This paper describes a network-based video capture and processing peripheral, called the Vidboard, for a distributed multimedia system centered around a 1-Gbit/s asynchronous transfer mode (ATM) network. The Vidboard is capable of generating full-motion video streams having a range of presentation (picture size, color space, etc.) and network (traffic, transport, etc.) characteristics. The board is also capable of decoupling video from the real-time constraints of the television world, which allows easier integration of video into the software environment of computer systems. A suite of ATM-based protocols has been developed for transmitting video from the Vidboard to a workstation, and a series of experiments are presented in which video is transmitted to a workstation for display.
A Free Boundary Problem Arising from Segregation of Populations with High Competition

In this work, we show how to obtain a free boundary problem as the limit of a fully nonlinear elliptic system of equations that models population segregation of the Gause–Lotka–Volterra type. We study the regularity of the solutions. In particular, we prove Lipschitz regularity across the free boundary. The problem is motivated by the work done by Caffarelli, Karakhanyan and Fang-Hua Lin for the linear case.
The use of effective medium theories for seismic wave propagation and fluid flow in fractured reservoirs under applied stress

SUMMARY Methods for predicting the permeability and elastic properties of hydrocarbon reservoirs containing natural fractures are important for the production optimization and seismic characterization of fractured reservoirs. Effective medium theories may be used for this purpose but need to be validated using numerical calculations of the fluid flow and seismic properties for realistic fracture networks. The prediction of effective permeability and elastic properties using effective medium theories of fractured media are compared with numerical simulations using a discrete fracture network (DFN) containing two sets of non-orthogonal vertical fractures. Discrepancies between the permeability obtained from the simulations and using effective medium theory are attributed to an oversimplified treatment of fracture interconnectivity in the effective medium theory used. The simulations indicate that the effect of interconnectivity on fluid flow varies with stress and flow direction. By contrast, the effective elastic compliances obtained from numerical simulation and effective medium theory are in good agreement, even for relatively complicated fracture networks. Although permeability and seismic anisotropy both vary with stress, the relation between them is not simple. The variation in reflection amplitude with offset and azimuth is found to be sensitive to the ratio of the normal to shear compliance of the fractures, whereas permeability is less sensitive to this ratio. For the DFN studied, the permeability rapidly increases at high level of stress due to dilation of the fractures when the in situ stress field is strongly anisotropic.
THE EFFECT OF CREDIT RISK ON BANK AND BANK HOLDING COMPANY BOND YIELDS: EVIDENCE FROM THE POST-FDICIA PERIOD

In this article we examine whether the federal safety net is viewed by the market as being extended beyond de jure deposits to other bank debt and even the debt of bank holding companies (BHCs). We extend previous research by focusing on the post-FDICIA period and by examining the risk-return relation of bonds issued directly by banks, not BHCs. Our results provide evidence that both bank and BHC bonds are priced by the secondary market in relation to their underlying credit risk, particularly for less capitalized issuers, suggesting that proposals requiring banks to issue subordinated debt may enhance market monitoring and discipline and be useful in supplementing regulatory discipline.