cssi/SciSciGPT-SciSciNet huggingface dataset:
Asymmetric beam combination for optical interferometry

Optical interferometers increasingly use single-mode fibers as spatial filters to convert varying wave-front distortion into intensity fluctuations which can be monitored for accurate calibration of fringe amplitudes. Here I propose using an asymmetric coupler to allow the photometric intensities of each telescope beam to be measured at the same time as the fringe visibility but without the need for dedicated photometric outputs, which reduce the light throughput in the interferometric channels. In the read-noise-limited case often encountered in the infrared, I show that a 53% improvement in signal-to-noise ratio for the visibility amplitude measurement is achievable, when compared to a balanced coupler setup with 50% photometric taps (e.g., the FLUOR experiment). In the Poisson-noise limit appropriate for visible light, the improvement is reduced to only ~8%. This scheme also reduces the cost and complexity of the beam combination since fewer components and detectors are required and since it can be extended to more than two telescopes for "all-in-one" or pairwise beam combination. Asymmetric beam combination can also be employed for monitoring scintillation and throughput variations in systems without spatial filtering.
Aeroservoelastic DAP missile fin development

The development of an active aeroservoelastic missile fin using directionally attached piezoelectric (DAP) actuator elements is detailed. Several different types of actuator elements are examined, including piezoelectric polymers, piezoelectric fiber composites, and conventionally attached piezoelectric (CAP) and DAP elements. These actuator elements are bonded to the substrate of a torque plate. The root of the torque plate is attached to a fuselage hard point or folding pivot. The tip of the plate is bonded to an aerodynamic shell which undergoes a pitch change as the plate twists. The design procedures used on the plate are discussed. A comparison of the various actuator element shows that DAP elements provide the highest deflections with the highest torsional stiffness. A torque plate was constructed from 0.2032 mm thick DAP elements bonded to a 0.127 mm thick AISI 1010 steel substrate. The torque plate produced static twist deflections in excess of +/- 3 deg. An aerodynamic shell with a modified NACA 0012 profile was added to the torque plate. This fin was tested in a wind tunnel at speeds up to 50 ms/sec. The static deflection of the fin was predicted to within 6 percent of the experimental data.
Concepts and technologies for synthetic aperture radar from MEO and geosynchronous orbits

The area accessible from a spaceborne imaging radar, e.g. a synthetic aperture radar (SAR), generally increases with the elevation of the satellite while the map coverage rate is a more complicated function of platform velocity and beam agility. The coverage of a low Earth orbit (LEO) satellite is basically given by the ground velocity times the relatively narrow swath width. The instantaneously accessible area will be limited to some hundreds of kilometers away from the sub-satellite point. In the other extreme, the sub-satellite point of a SAR in geosynchronous orbit will move relatively slowly, while the area which can be accessed at any given time is very large, reaching thousands of kilometers from the sub-satellite point. To effectively use the accessibility provided by a high vantage point, very large antennas with electronically steered beams are required. Interestingly, medium Earth orbits (MEO) will enable powerful observational systems which provide large instantaneous reach and high mapping rates, while pushing technology less than alternative systems at higher altitudes. Using interferometric SAR techniques which can reveal centimeter-level (potentially sub-centimeter) surface displacements, frequent and targeted observations might be key to developing such elusive applications as earthquake forecasting. This paper discusses the basic characteristics of a SAR observational system as a function of the platform altitude and the technologies being developed to make such systems feasible.
Annotated revision programs

Revision programming is a formalism to describe and enforce updates of belief sets and databases. That formalism was extended by Fitting who assigned annotations to revision atoms. Annotations provide a way to quantify the confidence (probability) that a revision atom holds. The main goal of our paper is to reexamine the work of Fitting, argue that his semantics does not always provide results consistent with intuition, and to propose an alternative treatment of annotated revision programs. Our approach differs from that proposed by Fitting in two key aspects: we change the notion of a model of a program and we change the notion of a justified revision. We show that under this new approach fundamental properties of justified revisions of standard revision programs extend to the annotated case.
The Transformative Power of X-Rays in U.S. Scientific & Medical Litigation: Mechanical Objectivity in Smith v. Grant (1896).

The paper locates the struggle to mobilize and regulate the immense social and cultural power inherent in X-rays’ capacity to remotely anatomize the living body power within the discursive space of the turn-of-the-century American courtroom. The paper pioneers use of extant court records in the seminal case of Smith v. Grant, the first American medical malpractice case in which an injured plaintiff successfully introduced X-ray evidence against a physician. The paper demonstrates how X-ray images catalyzed crucial changes in the American law of scientific and medical evidence and facilitated a novel regime for their regulation that continues to reverberate in the present.
Fabrication of Asymmetric Electrode Pairs with Nanometer Separation Made of Two Distinct Metals

We report a simple and reproducible method to fabricate two metallic electrodes made of different metals with a nanometer-sized gap. These electrodes are fabricated by defining a pair of gold electrodes lithographically and electrodepositing a second metal onto one of them. This method enables the fabrication of pairs of metallic electrodes that exhibit distinct magnetic properties or work functions. The utility of this technique is demonstrated by making single-electron tunneling devices incorporating 2-nm gold nanocrystals.
Public Information Quality with Monopolistic Sellers

Abstract We show that in markets with asymmetric information, even if there is full agreement on the choice of optimal information quality, entrusting the choice of (unverifiable) public information quality to traders who benefit from such information leads to inefficiencies. However, delegation of information quality choice to an independent agent who is precluded from sharing in trading profits results in efficient implementation. This result provides a game-theoretic rationale for current institutional arrangements where a private organization that is independent of market traders, the Financial Accounting Standards Board, determines the standards for public disclosures. Journal of Economic Literature Classification Numbers: D41, D42, D82.
Genetic algorithm for optimization and specification of a neuron model

We present a novel approach for neuron model specification using a genetic algorithm (GA) to develop simple firing neuron models consisting of a single compartment with one inward and one outward current. The GA not only chooses the model parameters, but also chooses the formulation of the ionic currents (i.e. single-state variable, two-state variable, instantaneous, or leak). The fitness function of the GA compares the frequency output of the GA-generated models to an I-F curve of a nominal Morris-Lecar (ML) model. Initially, several different classes of models compete within the population. Eventually, the GA converges to a population containing only ML-type firing models, that is, models with an instantaneous inward and single-state variable outward current. Simulations where ML-type models are restricted from the population are also investigated. This GA approach allows the exploration of a universe of feasible model classes that is less constrained by model formulation assumptions than traditional parameter estimation approaches.
Excited electronic states from a variational approach based on symmetry-projected Hartree–Fock configurations

Recent work from our research group has demonstrated that symmetry-projected Hartree–Fock (HF) methods provide a compact representation of molecular ground state wavefunctions based on a superposition of non-orthogonal Slater determinants. The symmetry-projected ansatz can account for static correlations in a computationally efficient way. Here we present a variational extension of this methodology applicable to excited states of the same symmetry as the ground state. Benchmark calculations on the C2 dimer with a modest basis set, which allows comparison with full configuration interaction results, indicate that this extension provides a high quality description of the low-lying spectrum for the entire dissociation profile. We apply the same methodology to obtain the full low-lying vertical excitation spectrum of formaldehyde, in good agreement with available theoretical and experimental data, as well as to a challenging model C2v insertion pathway for BeH2. The variational excited state methodology devel...
Relational Quantum Mechanics and the Determinacy Problem

Quantum mechanics describes certain systems as being in superpositions of their properties, yet every measurement on every system that we are able to perform yields a determinate result. The ``orthodox'' formulation of the theory builds this in by including a postulate that such superpositions ``collapse'' at the time of measurement. This strategy fails to really explain why such measurements are determinate, is unacceptably imprecise, and makes observation basic in fundamental physical theory, which looks like the wrong sort of process for the job. The problem of the interpretation of quantum mechanics is the problem of finding a more satisfactory understanding of the formalism in the face of these problems. Carlo Rovelli's relational interpretation of quantum mechanics holds that a system's states or the values of its physical quantites as normally conceived only exist relative to a cut between a system and an observer or measuring instrument. Furthermore, on Rovelli's account, the appearance of determinate observations from pure quantum superpositions happens only relative to the interaction of the system and observer. Jeffrey Barrett has pointed out that certain relational interpretations suffer from what we might call the ``determinacy problem,'' but the interpretations that Barrett considers make facts relative to branches of the universal wave function rather than to system/observer cuts. Thus, Barrett misclassifies Rovelli's interpretation, which differs from the interpretations that Barrett explicitly worries about and has the resources to escape his particular criticisms. Rovelli's interpretation still leaves us with a paradox having to do with the determinacy of measurement outcomes, which can be accepted only if we are willing to give up on certain elements of the ``absolute'' view of the world.
An all-silicon passive optical diode

We demonstrate an optical diode with up to 28dB transmission contrast at telecommunication wavelengths. It is based on strong optical nonlinearity in two resonance-matched silicon microrings. No external assistance other than input light is required.
Convergence of mean curvature flows with surgery

Huisken and Sinestrari have recently defined a surgery process for mean curvature flow when the initial data is a two-convex hypersurface. The process depends on a parameter H. Its role is to initiate a surgery when the maximum of the mean curvature of the evolving hypersurface becomes H, and to control the scale at which each surgery is performed. We prove that as H goes to infinity the surgery process converges to level set flow.
The First Intermolecular Friedel−Crafts Acylation with β-Lactams

The first intermolecular Friedel−Crafts acylation of a variety of aromatic substrates with azetidinones is described. The Friedel−Crafts acylations are performed under very mild conditions, using trifluoromethanesulfonic acid to produce β-amino aromatic ketones in excellent yields.
THE CONTRIBUTION OF THE LIGHT QUARK CONDENSATE TO THE πN SIGMA TERM

There has been a discrepancy between values of the pion-nucleon sigma term extracted by two different methods for many years. Analysis of recent high precision pion-nucleon data has widened the gap between the two determinations. It is argued that the two extractions correspond to different quantities and that the difference between them can be understood and calculated.
Asymmetric synthesis of 1-acyl-3,4-disubstituted pyrrolidine-2-boronic acid derivatives

Abstract An analogue of N -acetylkainic acid having a cyano group and a boronic acid group in place of the two carboxyl groups has been synthesized with high stereocontrol via a series of chain extensions of pinanediol [(trityloxy)methyl]boronate with (dihalomethyl)lithium followed by appropriate nucleophilic substitution of the resulting chloro or bromo boronic ester. Substituents were introduced in the order isopropenyl, cyanomethyl, and bis(trimethylsilyl)amino. The last of these was converted to acetamido, the hydroxyl function was unmasked and mesylated, and the pyrrolidine ring was closed. Attempts to carry out further chain extension on the boronic ester resulted in low yields, evidently the highly polar amido substituent interferes with the (dichloromethyl)lithium insertion process.
Conservatism measures that control for the effects of economic rents on stock returns

Recent studies show that regression-based estimates of accounting conservatism reflect both differences in the asymmetric recognition of bad news and differences in asset composition. In particular, a firm’s market value and returns reflect both assets-in-place and expected future rents, while book values tend to reflect only assets-in-place. We propose two tests that remove the effect of asset composition on cross-sectional comparisons of accounting conservatism. First, a test based on a ratio of regression coefficients allows for valid cross-sectional comparisons of conservatism relative to overall news recognition. Second, in some cases, researchers can separately identify and make cross-sectional comparisons of the fraction of good news recognized and the fraction of bad news recognized. The estimates in this second scenario use a regression of earnings on returns interacted with a book-to-market ratio. We validate our model by deriving and testing several predictions based on it.
Optimal surface reconstruction from planar contours

In many scientific and technical endeavors, a three-dimensional solid must be reconstructed from serial sections, either to aid in the comprehension of the object's structure or to facilitate its automatic manipulation and analysis. This paper presents a general solution to the problem of constructing a surface over a set of cross-sectional contours. This surface, to be composed of triangular tiles, is constructed by separately determining an optimal surface between each pair of consecutive contours. Determining such a surface is reduced to the problem of finding certain minimum cost cycles in a directed toroidal graph. A new fast algorithm for finding such cycles is utilized. Also developed is a closed-form expression, in terms of the number of contour points, for an upper bound on the number of operations required to execute the algorithm. An illustrated example which involves the construction of a minimum area surface describing a human head is included.
Model studies of (+)-bergenin: A convenient formation of aryl δ-lactones

Abstract The reaction of o-carboxyarylpropargyl bromides with aldehydes mediated by indium in aqueous medium conveniently generated aryl δ-lactones. The product formation was affected by the nature of the co-solvent.
New Constraints on the Nature of Radio Emission in Sagittarius A

The millimeter to submillimeter spectrum of Sagittarius A* at the Galactic center, as well as its polarization characteristics, are consistent with the inner ~10 Schwarzschild radii of a tight Keplerian emitting region of hot, magnetized, orbiting gas. This plasma may also be the source (through self-Comptonization) of the X-rays detected by Chandra. It has long been suspected that the circularization region between the quasi-spherical infall at large radii, and this inner zone, is responsible for producing the rest of Sgr A*'s spectrum. In this Letter, we report the results of a detailed study of this region, with several important conclusions that will be highly relevant to upcoming coordinated multiwavelength observations. First, the combination of existing centimeter and X-ray data preclude the possibility of producing the observed strong 1.36 GHz radio flux via thermal synchrotron within a bounded flow. If Sgr A*'s radio spectrum is produced by accreting gas, it appears that a nonthermal particle distribution is a necessity. This may not be surprising, given that the energy associated with the radial motion is probably dissipated by shocks before the gas circularizes, which can produce the required power-law distribution. Second, if this is the correct picture for how Sgr A*'s spectrum is produced, it appears that the Chandra-detected X-rays may originate either from self-Comptonization in the inner Keplerian region or from optically thin nonthermal synchrotron emission in the much larger circularization zone, extending up to 500 Schwarzschild radii or more. This is a question that should be answered by upcoming broadband observations, since the millimeter bump and X-rays are strongly correlated in the former case, whereas the X-rays are strongly correlated to the centimeter radio flux in the latter. In addition, X-rays produced in the circularized gas could show periodic or quasi-periodic variations but not those produced via nonthermal synchrotron emission much farther out.
Elevated serum α(1 → 3)-l-fucosyltransferase activity with synthetic low molecular weight acceptor in human ovarian cancer

Serum alpha(1----3)-L-fucosyltransferase activity was measured in 29 ovarian cancer patients with active disease, 26 ovarian cancer patients with no clinical evidence of disease and 23 healthy females. N-Acetyl-2'-O-methyl-lactosamine was used as the acceptor for the enzyme. The level of the enzyme activity was significantly (P less than 0.05) higher in the serum of patients with known tumor when compared to healthy controls and patients with no clinical evidence of disease.
A formula periodic table for benzenoid hydrocarbons and the aufbau and excised internal structure concepts in benzenoid enumerations

The genesis of the aufbau and excised internal structure concepts is traced. These concepts were pivotal to the first published enumerations of the strictly peri-condensed, non-Kekulean, and essentially strain-free total resonant sextet benzenoid groups. Aperiodic table set is defined as a partially ordered set forming a two-dimensional array which complies with thetriad principle where a central element has a metric property that is the arithmetic mean of two adjacent surrounding member elements.
Nondispersing wave packets

A nondispersing Rydberg wave packet can be made by applying a weak, linearly polarized field at the Kepler frequency of a Rydberg atom. The field phase locks the electron's motion to the microwave field, and the wave packet retains its spatial localization for times in excess of a microsecond. The electron's orbital oscillation leads to an oscillating dipole, which can either oscillate in phase or out of phase with the applied microwave field, creating wave packets analogous to Trojan and anti-Trojan wave packets described theoretically. Our observations can be described in both quantum mechanical and classical terms.
THE NIRSPEC ULTRACOOL DWARF RADIAL VELOCITY SURVEY

We report the results of an infrared Doppler survey designed to detect brown dwarf and giant planetary companions to a magnitude-limited sample of ultracool dwarfs. Using the NIRSPEC spectrograph on the Keck II telescope, we obtained approximately 600 radial velocity (RV) measurements over a period of six years of a sample of 59 late-M and L dwarfs spanning spectral types M8/L0 to L6. A subsample of 46 of our targets has been observed on three or more epochs. We rely on telluric CH4 absorption features in Earth's atmosphere as a simultaneous wavelength reference and exploit the rich set of CO absorption features found in the K-band spectra of cool stars and brown dwarfs to measure RVs and projected rotational velocities. For a bright, slowly rotating M dwarf standard we demonstrate an RV precision of 50 m s–1 and for slowly rotating L dwarfs we achieve a typical RV precision of approximately 200 m s–1. This precision is sufficient for the detection of close-in giant planetary companions to mid-L dwarfs as well as more equal mass spectroscopic binary systems with small separations (a < 2 AU). We present an orbital solution for the subdwarf binary LSR1610 – 0040 as well as an improved solution for the M/T binary 2M0320 – 04. We compare the distribution of our observed values for the projected rotational velocities, Vsin i, to those in the literature and find that our sample contains examples of slowly rotating mid-L dwarfs, which have not been seen in other surveys. We also combine our RV measurements with distance estimates and proper motions from the literature and estimate the dispersion of the space velocities of the objects in our sample. Using a kinematic age estimate, we conclude that our UCDs have an age of 5.0+0.7 –0.6 Gyr, similar to that of nearby sun-like stars. We simulate the efficiency with which we detect spectroscopic binaries and find that the rate of tight (a < 1 AU) binaries in our sample is 2.5+8.6 –1.6%, consistent with recent estimates in the literature of a tight binary fraction of 3%-4%.
New examples of duality in chiral and non-chiral supersymmetric gauge theories

Abstract We present evidence for renormalization group fixed points with dual magnetic descriptions in fourteen new classes of four-dimensional N = 1 supersymmetric models. Nine of these classes are chiral and many involve two or three gauge groups. These theories are generalizations of models presented earlier by Seiberg, by Kutasov and Schwimmer, and by the present authors. The different classes are interrelated; one can flow from one class to another using confinement or symmetry breaking.
Metals in Neurobiology: Probing Their Chemistry and Biology with Molecular Imaging

The brain is a singular organ of unique biological complexity that serves as the command center for cognitive and motor function. As such, this specialized system also possesses a unique chemical composition and reactivity at the molecular level. In this regard, two vital distinguishing features of the brain are its requirements for the highest concentrations of metal ions in the body and the highest per-weight consumption of body oxygen. In humans, the brain accounts for only 2% of total body mass but consumes 20% of the oxygen that is taken in through respiration. As a consequence of high oxygen demand and cell complexity, distinctly high metal levels pervade all regions of the brain and central nervous system. Structural roles for metal ions in the brain and the body include the stabilization of biomolecules in static (e.g., Mg2+ for nucleic acid folds, Zn2+ in zinc-finger transcription factors) or dynamic (e.g., Na+ and K+ in ion channels, Ca2+ in neuronal cell signaling) modes, and catalytic roles for brain metal ions are also numerous and often of special demand.
Complementary barrier infrared detector (CBIRD) with double tunnel junction contact and quantum dot barrier infrared detector (QD-BIRD)

Abstract The InAs/GaSb type-II superlattice based complementary barrier infrared detector (CBIRD) has already demonstrated very good performance in long-wavelength infrared (LWIR) detection. In this work, we describe results on a modified CBIRD device that incorporates a double tunnel junction contact designed for robust device and focal plane array processing. The new device also exhibited reduced turn-on voltage. We also report results on the quantum dot barrier infrared detector (QD-BIRD). By incorporating self-assembled InSb quantum dots into the InAsSb absorber of the standard nBn detector structure, the QD-BIRD extend the detector cutoff wavelength from ∼4.2 μm to 6 μm, allowing the coverage of the mid-wavelength infrared (MWIR) transmission window. The device has been observed to show infrared response at 225 K.
Ion-optics calculations and preliminary precision estimates of the gas-capable ion source for the 1-MV LLNL BioAMS spectrometer

Abstract Ion-optics calculations were performed for a new ion source and injection beam line. This source, which can accept both solid and gaseous targets, will be installed onto the 1-MV BioAMS spectrometer at the Center for Accelerator Mass Spectrometry, located at Lawrence Livermore National Laboratory and will augment the current LLNL cesium-sputter solid sample ion source. The ion source and its associated injection beam line were designed to allow direct quantification of 14C/12C and 3H/1H isotope ratios from both solid and gaseous targets without the need for isotope switching. Once installed, this source will enable the direct linking of a nanoflow LC system to the spectrometer to provide for high-throughput LC-AMS quantitation from a continuous flow. Calculations show that, for small samples, the sensitivity of the gas-accepting ion source could be precision limited but zeptomole quantitation should be feasible.
Improved ion containment using a ring-cusp ion thruster

A 30-centimeter diameter ring-cusp ion thruster is described which operates at inert gas ion beam currents up to about 7 ampere, with significant improvements in discharge chamber performance over conventional divergent-field thrusters. The thruster has strong boundary ring-cusp magnetic fields, a diverging field on the cathode region, and a nearly field-free volume upstream of the ion extraction system. Minimum ion beam production costs of 90 to 100 watts per beam ampere (W/A) were obtained for argon, krypton and xenon. Propellant efficiencies in excess of 0.90 were achieved at 100 to 120 W/A for the three inert gases. The ion beam charge-state was documented with a collimating mass spectrometer probe to allow evaluation of overall thruster efficiencies.
What is driving economic and financial success of US cow-calf operations?

Purpose – The purpose of this paper is to determine the drivers of economic financial success of US cow-calf operations. Design/methodology/approach – This research uses a system of equations (DuPont analysis) in conjunction with 2008 farm-level data from the US Department of Agriculture's Agricultural Resource Management Survey to evaluate the factors driving cow-calf profitability, namely net profit margins, asset turnover ratio, and asset-to-equity ratio. Findings – The study finds that the main drivers of return on equity are region, number of harvested acres on the farm, diversification of the farm, operator off-farm work, spousal off-farm work, and adoption of technologies. Of these factors, those for which producers can make short-term adjustments include off-farm work decisions and adoption of technologies. Longer-term adjustments can be made for farm diversification. Originality/value – To the authors’ knowledge, no existing research has used farm-level data across US production regions to examin...
X-ray thin foil filters at cryogenic temperatures

The X-Ray Spectrometer (XRS), which is being developed for one of the focal plane instruments of the Advanced X-Ray Astrophysics Facility, requires filters with high X-ray transmittance, high background rejection, and operation at cryogenic temperatures. Thin foil filters can provide high X-ray transmittance and the required rejection for low-energy radiation. The results of the test program demonstrate that these filters are fully successful at cryogenic temperatures and, therefore, can provide blocking filters for the XRS with the required performance.
Fuel Microemulsions for Jet Engine Smoke Reduction

Abstract : The concept of water and alcohol/fuel microemulsions for the purpose of reducing smoke emissions from jet engine test cells was studied in a T-63 gas turbine combustor. Several ethanol/fuel, methanol/fuel and water/fuel microemulsions were prepared with JP-4 and JP-8 base fuels and the appropriate surfactants. Both metallic (ferrocene) and nonmetallic (hydrazine) smoke-reducing additives were examined for possible synergistic effects when combined with the microemulsified fuels. The fuels were tested at the takeoff, climb, cruise and ground idle operating condition, and the exhaust smoke, flame radiation and gaseous emissions were measured. The exhaust smoke and flame radiation were significantly reduced by the additions of alcohols and water to the base fuels. Ethanol was found to be most cost effective because it required the least amount of surfactant, which was the most expensive fuel component. The tendency of the microemulsions to form soot was found to correlate with H/C ratio in the same way as typical petroleum-base fuels. Ferrocene, which is well known for its ability to reduce exhaust smoke, had the same effect on the microemulsions as the base fuels; it did not affect flame radiation. Hydrazine was not an effective additive for reducing exhaust smoke.
Efficiency and information aggregation in auctions

The tension between allocative efficiency and information aggregation is explored in the context of an auction: k identical objects of unknown quality are auctioned off to n bidders whose tastes affect their valuation of an object of given quality. Bidders receive a signal about the quality of the objects. The k highest bidders get an object and pay a price equal to the k + first highest bid. We find conditions under which, in the limit, objects are allocated efficiently to those with the highest tastes, and price converges in probability to the value of an object to the marginal taste type.
Alignment of Speech to Highly Imperfect Text Transcriptions

We introduce a novel and inexpensive approach for the temporal alignment of speech to highly imperfect transcripts from automatic speech recognition (ASR). Transcripts are generated for extended lecture and presentation videos, which in some cases feature more than 30 speakers with different accents, resulting in highly varying transcription qualities. In our approach we detect a subset of phonemes in the speech track, and align them to the sequence of phonemes extracted from the transcript. We report on the results for 4 speech-transcript sets ranging from 22 to 108 minutes. The alignment performance is promising, showing a correct matching of phonemes within 10, 20, 30 second error margins for more than 60 %, 75 %, 90 % of text, respectively, on average. For perfect manually generated transcripts, more than 75 % of text is correctly aligned within 5 seconds.
Discovery of the cobalt isotopes

Twenty-six cobalt isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.
Density fluctuations in classical monatomic liquids

Abstract A form for the density response of a classical liquid in the range k ∼ 0.5A -1 and ω ∼ 10 13 sec -1 is proposed which has a simple form and gives a good description of Rahman's molecular dynamics results.
Application of Genetic Algorithms in the Engine Technology Selection Process

The objective of this paper is to demonstrate the application of genetic algorithms to the engine technology selection process. The technology identification, evaluation, and selection method is discussed in conjunction with genetic algorithm optimization as a technique to quickly: evaluate the impact of various technologies and select the subset with the highest potential payoff Techniques used to model various aspects of engine technologies are described, with emphasis on technology constraints and their impact on the combinatorial optimization of technologies. Challenges include objective function formulation and development of models to deal with incompatibilities among different technologies. Typical results are presented for an 80-technology optimization using various visualization techniques to assist in easy interpretation of genetic algorithm results. Finally, several ideas for future development of these methods are briefly explored.
p53 Controls Radiation-Induced Gastrointestinal Syndrome in Mice Independent of Apoptosis

Acute exposure to ionizing radiation can cause lethal damage to the gastrointestinal (GI) tract, a condition called the GI syndrome. Whether the target cells affected by radiation to cause the GI syndrome are derived from the epithelium or endothelium and whether the target cells die by apoptosis or other mechanisms are controversial issues. Studying mouse models, we found that selective deletion of the proapoptotic genes Bak1 and Bax from the GI epithelium or from endothelial cells did not protect mice from developing the GI syndrome after sub-total-body gamma irradiation. In contrast, selective deletion of p53 from the GI epithelium, but not from endothelial cells, sensitized irradiated mice to the GI syndrome. Transgenic mice overexpressing p53 in all tissues were protected from the GI syndrome after irradiation. These results suggest that the GI syndrome is caused by the death of GI epithelial cells and that these epithelial cells die by a mechanism that is regulated by p53 but independent of apoptosis.
Bit-interleaved space-frequency coded Modulation for OFDM systems

We present an orthogonal frequency-division multiplexing (OFDM) system with bit-interleaved space-frequency coded modulation for frequency-selective fading channels employing multiple transmit and receive antennas. OFDM is used to transform a frequency-selective fading channel into multiple flat fading channels, and space-frequency trellis coding combined with bit-interleaving is used to exploit space and frequency diversity. The performance of such an approach is evaluated by analytical bounds and simulation. The proposed scheme is an efficient method to employ multiple transmit antennas to increase the data rate and, at the same time, improve the performance by means of increased diversity obtained with bit-interleaved coded modulation and multiple receive antennas. A block precoding method is proposed to further improve the diversity order. An efficient sphere decoding algorithm is also developed for reducing the decoding complexity of the proposed scheme.
Post-T Tauri Stars in the Nearest OB Association

We present results of a spectroscopic survey of X-ray– and proper-motion–selected samples of late-type stars in the Lower Centaurus–Crux (LCC) and Upper Centaurus–Lupus (UCL) subgroups of the nearest OB association: Scorpius-Centaurus. The primary goals of the survey are to determine the star formation history of the OB subgroups and to assess the frequency of accreting stars in a sample dominated by "post–T Tauri" pre–main-sequence (PMS) stars. We investigate two samples: (1) proper-motion candidates from the ACT Catalog and Tycho Reference Catalog (TRC) with X-ray counterparts in the ROSAT All-Sky Survey (RASS) Bright Source Catalog and (2) G- and K-type stars in the Hipparcos catalog found to be candidate members by de Zeeuw et al. We obtained optical spectra of 130 candidates with the Siding Spring 2.3 m dual-beam spectrograph. PMS stars were identified by (1) strong Li λ6707 absorption, (2) subgiant surface gravities, (3) proper motions consistent with Sco-Cen membership, and (4) H-R diagram positions consistent with being PMS. We find 93% of the RASS-ACT/TRC stars to be probable PMS members, compared with 73% of the Hipparcos candidates. We demonstrate that measuring the gravity-sensitive band ratio of Sr II λ4077 to Fe I λ4071 is a valuable means of discriminating PMS and zero-age main-sequence (ZAMS) stars. Using secular parallaxes and Hipparcos, Tycho-2, and Two Micron All Sky Survey photometry, we construct an H-R diagram. Depending on the choice of published evolutionary tracks, we find the mean ages of the PMS populations to range between 17 and 23 Myr for LCC and 15 and 22 Myr for UCL. Taking into account observational errors, it appears that 95% of the low-mass star formation in each subgroup must have occurred in less than 8 Myr (LCC) and 12 Myr (UCL). Using the Bertelli et al. tracks, we find main-sequence turnoff ages for Hipparcos B-type members to be 16 ± 1 Myr for LCC and 17 ± 1 Myr for UCL. Contrary to previous findings, it appears that LCC is coeval with, or slightly older than, UCL. The secular parallaxes of the Sco-Cen PMS stars yield distances of 85–215 pc, with 12 of the LCC members lying within 100 pc of the Sun. Only one out of 110 (0.9%; 1 σ) PMS solar-type stars in the sample with ages of 13 ± 1 (s.e.) ± 6 (1 σ) Myr and masses of 1.3 ± 0.2 (1 σ) M⊙ shows both enhanced Hα emission and a K-band excess indicative of accretion from a truncated circumstellar disk: the nearby (d 86 pc) classical T Tauri star PDS 66.
Rhodium-catalyzed carbonylation of cyclopropyl substituted propargyl esters: a tandem 1,3-acyloxy migration [5 + 1] cycloaddition.

We have developed two different types of tandem reactions for the synthesis of highly functionalized cyclohexenones from cyclopropyl substituted propargyl esters. Both reactions were initiated by rhodium-catalyzed Saucy–Marbet 1,3-acyloxy migration. The resulting cyclopropyl substituted allenes derived from acyloxy migration then underwent [5 + 1] cycloaddition with CO. The acyloxy group not only eased the access to allene intermediates but also provided a handle for further selective functionalizations.
Connectivity graphs as models of local interactions

In this paper, we study graphs that arise from certain sensory and communication limitations on the local interactions in multi-agent systems. In particular, we show that the set of graphs that can represent formations corresponds to a proper subset of all graphs and we denote such graphs as connectivity graphs. These graphs have a special structure that allows them to be composed from a small number of atomic generators using a certain kind of graph amalgamation. This structure moreover allows us to give connectivity graphs a topological characterization in terms of their simplicial complexes. Finally, we outline some applications of this topological characterization to the construction of decentralized algorithms.
Automating the Process of Terminal Area Node-Link Model Generation

Currently, few detailed airport surface models for air transportation system simulation and analysis exist, because the models are complex to develop and maintain. An improved method of generating detailed models is needed to expand the set of detailed airport surface and terminal airspace models. In this paper, an efficient means to automate the procedures to develop airport surface node-link graph models is proposed. Node-link graphs were created by connecting the centroids of the polygons from geographic information system data. A principal axis-based algorithm was formulated to identify and divide complex polygons. The graph was further improved by adjusting node positions, using the known centerlines from rectangular polygons and removing redundant nodes and links. The procedures were tested on 79 United States airports and proved to be robust, accurate, and efficient.
Reminiscing about the early years of the X-ray laser

To put the development of the X-ray laser in historic context, this paper presents some of the motivation and history of the development of the X-ray laser from the perspective of a scientist at the Lawrence Livermore National Laboratory where the first X-ray laser was demonstrated in the early 1980s using a nuclear device as the driver.
Hyperbolic Discounting and the Sustainability of Rotational Savings Arrangements

People across the developing world join rotational savings and credit associations (roscas) to fund repeated purchases of nondivisible goods. When the scope for punishment is weak, there is a natural question about why agents do not defect from these groups. I model a rosca as a commitment savings device for hyperbolic discounters. Roscas are attractive for two reasons: the possibility of getting the nondivisible good early (the standard reason), and the fixed saving requirement (valued only by time-inconsistent agents). I find explicit conditions under which an agent strictly prefers to remain in a rosca, even in the absence of formal contracting or social punishment. I show why, unlike with standard commitment products, a hyperbolic discounter will not postpone entry into a rosca. Finally, this paper makes predictions about the relative survival of random and fixed roscas. Random roscas are more resilient and beneficial than fixed roscas when information is limited and matching for new roscas is fast.
Synthesis of 1-(o-substituted-phenyl)-3,4-dimethylenepyrrolidines by the thermal elimination of sulfur dioxide

Precursors of 1-(o-substituted-phenyl)-3,4-dimethylenepyrrolidines, 5-(o-substituted-phenyl)-1,3,4,6-tetra-hydrothieno[3,4-c]pyrrole 2,2- dioxides 2, were synthesized by reacting o-substituted anilines with 3,4-bis(bromomethyl)-2,5-dihydrothiophene 1,1-dioxide. A disubstitution product along with the desired 2 was obtained when excess amine was used to neutralize the amine salts that were formed from nucleophilic substitution. A 1,4-HBr elimination product was obtained in three out of four cases when sodium carbonate was used to neutralize the amine salts. The 1,4-HBr elimination product resulted from a competing base attack on the acidic sulfolene protons. The 3,4-dimethylenepyrrolidines were obtained by thermal elimination of sulfur dioxide from 2.
Fast algorithms for phase-diversity-based blind deconvolution

Phase diversity is a technique for obtaining estimates of both the object and the phase, by exploiting the simultaneous collection of two short-exposure optical images, one of which has been formed by further blurring regularized variant of the Gauss-Newton optimization method for phase diversity-based estimated when a Gaussian likelihood fit-to-data criterion is applied. Simulation studies are provided to demonstrate that the method is remarkably robust and numerically efficient.
Co-phasing the Large Binocular Telescope: status and performance of LBTI/PHASECam

The Large Binocular Telescope Interferometer is a NASA-funded nulling and imaging instrument designed to coherently combine the two 8.4-m primary mirrors of the LBT for high-sensitivity, high-contrast, and high-resolution infrared imaging (1.5-13 μm). PHASECam is LBTI's near-infrared camera used to measure tip-tilt and phase variations between the two AO-corrected apertures and provide high-angular resolution observations. We report on the status of the system and describe its on-sky performance measured during the first semester of 2014. With a spatial resolution equivalent to that of a 22.8-meter telescope and the light-gathering power of single 11.8-meter mirror, the co-phased LBT can be considered to be a forerunner of the next-generation extremely large telescopes (ELT).
The Cornell High-Order Adaptive Optics Survey for Brown Dwarfs in Stellar Systems. II. Results from Monte Carlo Population Analyses

In this second of a two-paper sequence, we present Monte Carlo population simulation results of brown dwarf companion data collected during the Cornell High-Order Adaptive Optics Survey (CHAOS) for brown dwarf companions. Making reasonable assumptions of orbital parameters (random inclination, random eccentricity, and random longitude of pericenter) and age distributions and using published mass functions, we find that the brown dwarf companion fraction around main-sequence stars is 0.0%-9.3% for the 25-100 AU semimajor axis region. We find a corresponding L dwarf companion fraction of 0.0%-3.3%. We compare our population analysis methods and results with techniques and results presented by several other groups. In this comparison we discover that systematic errors (most notably resulting from orbital projection effects) occur in the majority of previously published brown dwarf companion population estimates, leading authors to claim results not supported by the observational data.
Malthus and Climate Change: Betting on a Stable Population

Abstract A standard assumption in integrated assessment models of climate change is that population and productivity are growing, but at a decreasing rate. We explore the significance of the assumption of population and productivity growth for greenhouse gas abatement. After all, there has been no long run slowdown in the growth of productivity over the past few centuries, and the rate of population growth has actually been increasing for the past 19 centuries. Even if either of these growth rates were expected to slow, by how much is subject to great uncertainty. We show computationally that such continued growth greatly increases the severity of climate change. Indeed we find that climate change is a problem in large part “caused” by exogenous population and productivity growth. Rapid reductions in growth make climate change a small problem; smaller reductions in growth imply climate change is a very serious problem indeed. Analogously, reductions in the growth rate of population can be effective in controlling climate change.
Numerical design of electron guns and space charge limited transport systems

This paper describes the capabilities and limitations of computer programs used to design electron guns and similarly space-charge limited transport systems. Examples of computer generated plots from several different types of gun problems are included.
On the Security of a Practical Identification Scheme

We analyze the security of an interactive identification scheme. The scheme is the obvious extension of the original square root scheme of Goldwasser, Micali, and Rackoff to 2 m th roots. This scheme is quite practical, especially in terms of storage and communication complexity. Although this scheme is certainly not new, its security was apparently not fully understood. We prove that this scheme is secure if factoring integers is hard, even against active attacks where the adversary is first allowed to pose as a verifier before attempting impersonation.
A review of radiation effects in InP solar cells

Theoretically, InP has one of the highest solar energy conversion efficiencies of any semiconductor material. However, InP wafers are brittle and expensive which makes large area, single crystal InP device fabrication difficult. Despite this difficulty, research in InP solar cells has progressed rapidly over the past 10 years. The reason is high radiation tolerance. This quality is an essential feature of space power sources due to the harsh space radiation environment, and InP solar cells are more radiation resistant than the leading solar cell technologies, i.e. Si and GaAs. Therefore, InP solar cells are a very attractive space power source and have been seriously developed as such. This paper first reviews the chronology of this development and then takes a focused look at the present understanding of the mechanism of the radiation response of InP solar cells. >