cssi/SciSciGPT-SciSciNet huggingface dataset:
Expeditious One-Pot, Four-Step Preparation of 2-t-Butoxycarbonyl-6-hydroxy-1,2,3,4-tetrahydroisoquinoline and an Improved Conversion to Its 6-Cyano Derivative

3-Methoxy-phenethylamine was subjected to a sequential imination/Pictet–Spengler/demethylation/Boc protection sequence that allowed a one-pot preparation of N-Boc-6-hydroxy-1,2,3,4-tetrahydroisoquinoline 1. This intermediate was elaborated almost quantitatively via an improved triflation/cyanation procedure to its 6-cyano analog 2.
Chiral oxazolidinones as electrophiles: intramolecular cyclization reactions with carbanions and preparation of functionalized lactams

Abstract The intramolecular cyclizations of oxazolidinones with carbanions adjacent to sulfones, sulfoxides, and phosphonates proceed in high yields to obtain functionalized γ and δ lactams. The chiral oxazolidinone precursors can be readily synthesized from commercial amino acids. The lactams from this study are useful synthetic intermediates, as demonstrated by the synthesis of a precursor for levetiracetam, an antiepileptic drug.
Problem-Based Learning for Production and Operations Management

In this paper, we describe our application of “problem-based learning” in the teaching of production/operations management. We describe a study of the effectiveness of this approach and present the results and analysis of this study. We provide a collection of our experiences in using this method and conclude with some general observations on its appropriateness to the teaching of production/operations management.
A sewing-enabled stitch-and-transfer method for robust, ultra-stretchable, conductive interconnects

Fabricating highly stretchable and robust electrical interconnects at low-cost remains an unmet challenge in stretchable electronics. Previously reported stretchable interconnects require complicated fabrication processes with resulting devices exhibiting limited stretchability, poor reliability, and large gauge factors. Here, we demonstrate a novel sew-and-transfer method for rapid fabrication of low-cost, highly stretchable interconnects. Using a commercial sewing machine and double-thread stitch with one of the threads being water soluble polyvinyl alcohol (PVA), thin zigzag-pattern metallic wires are sewn into a polymeric film and are subsequently transferred onto a stretchable elastomeric substrate by dissolving PVA in warm water. The resulting structures exhibit extreme stretchability (exceeding 500% strain for a zigzag angle of 18 °) and robustness (capable of withstanding repeated stretch-and-release cycles of 15000 at 110% strain, 50000 at 55% strain, and > 120000 at 30% strain without any noticeable change in resistance even at maximum strain levels). Using this technique, we demonstrate a stretchable inductive strain sensor for monitoring balloon expansion in a Foley urinary catheter capable of detecting the balloon diameter change from 9 mm to 38 mm with an average sensitivity of 4 nH/mm.
Antenna array geometry and coding performance

This paper provides details about experiments in realistic, urban, and frequency flat channels with space-time coding that specifically examines the impact of the number of receive antennas and the design criteria for code selection on the performance. Also the performance characteristics are examined of the coded modulations in the presence of finite size array geometries. This paper gives some insight into which of the theories are most useful in realistic deployments
On-chip activation and subsequent detection of individual antigen-specific T cells.

The frequencies of antigen-specific CD4+ T cells in samples of human tissue have been difficult to determine accurately ex vivo, particularly for autoimmune diseases such as multiple sclerosis or type 1 diabetes. Conventional approaches involve the expansion of primary T cells in vitro to increase the numbers of cells, and a subsequent assessment of the frequencies of antigen-specific T cells in the expanded population by limiting dilution or by using fluorescently labeled tetramers of peptide-loaded major histocompatibility complex (MHC) receptors. Here we describe an alternative approach that uses arrays of subnanoliter wells coated with recombinant peptide-loaded MHC class II monomers to isolate and stimulate individual CD4+ T cells in an antigen-specific manner. In these experiments, activation was monitored using microengraving to capture two cytokines (IFNγ and IL-17) released from single cells. This new method should enable direct enumeration of antigen-specific CD4+ T cells ex vivo from clinical s...
Chemical Constraints on the Water and Total Oxygen Abundances in the Deep Atmosphere of Saturn

The mechanisms responsible for the observed H2O/H2 mixing ratio (HMR) in the Jovian troposphere are analyzed, with a focus on the relationship between HMR and O2 abundance and the abundance of the nonequilibrium trace gases CO and SiH4. The results of computations using a Jupiter atmosphere model consistent with recent observations (Bjoraker et al., 1986) are presented graphically and discussed in detail. It is found that the observed mixing ratios of CO (about 10 to the -9th) and SiH4 (upper limit 2-4 x 10 to the -9th) preclude O2 depletion and the presence of significant global H2O. The low observed HMRs (0.00003 at 6 bar) are tentatively attributed to local condensation in cloud-forming regions.
Human decision making under uncertainty and risk: computer-based experiments and a heuristic simulation program

Every organism of higher order has to make decisions of varying importance regularly and frequently in order to survive and to survive efficiently. While the outcome of decision making has been studied extensively by a wide range of different disciplines, the decision making processes themselves have been neglected in comparison. Emphasis has been placed on the normative aspects of human behavior, i.e., how a rational person or a group of rational persons ought to behave, as distinct from descriptive theories which are to explain and predict actual human behavior. An overwhelming majority of techniques and methods of attack in operations research, management science, industrial mathematics, etc. could be given the label: Normative Decision Theory. The students of mathematical psychology, on the other hand, beginning probably with Lady Lovelace, Bernoulli and Laplace, have been concerned with the behavioral aspects of decision making, i.e., what is being done in certain situations, and why.
A cryptographically sound security proof of the Needham-Schroeder-Lowe public-key protocol

We present a cryptographically sound security proof of the well-known Needham-Schroeder-Lowe public-key protocol for entity authentication. This protocol was previously only proved over unfounded abstractions from cryptography. We show that it is secure against arbitrary active attacks if it is implemented using standard provably secure cryptographic primitives. Nevertheless, our proof does not have to deal with the probabilistic aspects of cryptography and is, hence, in the scope of current automated proof tools. We achieve this by exploiting a recently proposed Dolev-Yao-style cryptographic library with a provably secure cryptographic implementation. Besides establishing the cryptographic security of the Needham-Schroeder-Lowe protocol, our result exemplifies the potential of this cryptographic library and paves the way for the cryptographically sound verification of security protocols by automated proof tools.
Analysis of a control system containing two nonlinearities

Analysis of control system containing two nonlinearities to determine existence, stability, and values of amplitude and limit cycles frequency
Does the Federal Government Learn from the States? Medicaid and the Limits of Expertise in the Intergovernmental Lobby

State programmatic expertise is an important asset to federal systems, but this expertise is not always informative to federal decision-makers. I argue the degree to which state expertise is informative to federal decision-makers depends on how well the policy interests of state and federal levels are aligned. I illustrate variation in these conditions using case studies of congressional politics over the Medicaid program. I then apply a statistical test, which demonstrates that states’ programmatic expertise regarding Medicaid is less persuasive to congressional committee members compared to other witnesses who are equally knowledgeable. The results suggest a “failure of federalism,” where the public good potential of state programmatic expertise often is not realized in the federal system.
The Copper Kettle: A historical perspective

Until 1952, the administration of inhaled volatile anesthetics was inexact because vaporizers in general use were not calibrated for either concentration or volume of vapor produced. These devices diverted a variable portion of fresh gas flow either through or over the liquid to be vaporized, but they lacked vernier or fine control. Therefore, changes in the concentration of the anesthetic vapor were not easily controlled. Dr. Lucien E. Morris standardized the administration of volatile anesthetics with his invention of the Copper Kettle, which produced known volumes of saturated vapor, then diluted to calculated concentrations necessary for anesthesia. To achieve this, modifications had to be made in the liquid container, circuit design, and vaporizing surfaces in use at the time. Morris' design incorporated a separately metered flow of carrier gas through the vaporizer to produce known volumes of saturated vapor for introduction into the fresh gas flow delivery.
The Advantages of Not Entangling Macroscopic Diamonds at Room Temperature

The recent paper entitled by K. C. Lee et al. (2011) establishes nonlocal macroscopic quantum correlations, which they term “entanglement”, under ambient conditions. Photon(s)-phonon entanglements are established within each interferometer arm. However, our analysis demonstrates, the phonon fields between arms become correlated as a result of single-photon wavepacket path indistinguishability, not true nonlocal entanglement. We also note that a coherence expansion (as opposed to decoherence) resulted from local entanglement which was not recognized. It occurred from nearly identical Raman scattering in each arm (importantly not meeting the Born and Markovian approximations). The ability to establish nonlocal macroscopic quantum correlations through path indistinguishability rather than entanglement offers the opportunity to greatly expand quantum macroscopic theory and application, even though it was not true nonlocal entanglement.
Optical signatures of molecular dissymmetry: combining theory with experiments to address stereochemical puzzles.

Modern chemistry emerged from the quest to describe the three-dimensional structure of molecules: van’t Hoff’s tetravalent carbon placed symmetry and dissymmetry at the heart of chemistry. In this ...
D-branes in Gepner models and supersymmetry

Boundary states corresponding to wrapped D-branes in Calabi-Yau compactifications of type II strings are discussed using Gepner models. In particular, boundary conditions corresponding to D0-branes and D-instantons in four dimensions are investigated. The boundary states constructed by Recknagel and Schomerus are analyzed in the light-cone gauge and the broken and conserved space-time supersymmetry changes are found. The geometrical interpretation of these algebraically constructed boundary states is clarified in some simple cases. Moreover, the action of mirror symmetry and other discrete symmetries of the Gepner model on the boundary states are discussed. As an application the boundary states are used to calculate instanton induced corrections to metric on the hypermultiplets in the N = 2 effective action.
Positron emission tomography with a large axial acceptance angle: signal-to-noise considerations

A volume imaging positron emission tomography (PET) scanner with a large acceptance angle, such as the PENN-PET, offers fine spatial sampling and resolution in three dimensions, and a high sensitivity because of the inclusion of all cross-plane rays. The signal-to-noise ratio (SNR) is used to evaluate image quality for different scanning conditions of the PENN-PET using an activated cylindrical phantom with cold spheres of various sizes. Raising the energy threshold to 400 keV improves the SNR by lowering the scatter fraction, though it also reduces the sensitivity. Increasing the axial acceptance angle from +or-1.3 degrees to +or-6.5 degrees improves the SNR by increasing the sensitivity, even with a two-dimensional reconstruction algorithm, which compromises spatial resolution in the axial direction for points at the edge of the radial field of view. Initial results show that a three-dimensional reconstruction offers an improved SNR over a two-dimensional reconstruction that does not use all cross-plane rays. >
Efficient Hydrolysis of Organotrifluoroborates via Silica Gel and Water

A general, mild, and efficient method for the hydrolysis of organotrifluoroborates to unveil boronic acids using silica gel and H2O was developed. This method proved to be tolerant of a broad range of aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates as well as structurally diverse aminomethylated organotrifluoroborates. As anticipated, electron-rich substrates provided the corresponding boronic acids more readily than electron-poor substrates, owing to the resonance-stabilized difluoroborane intermediate. The method developed was expanded further for the conversion of organotrifluoroborates to the corresponding boronate esters.
CRACKING OF GaN FILMS

The cracking of GaN films and the associated cracking of substrates are described. The geometry, structure, and evolution of fracture demonstrate that GaN films crack under tensile stress during growth and are subsequently overgrown and partially healed. The film cracks channel along the (1010)GaN planes and also extend a distance of ~5 μm into the sapphire substrate. These incipient cracks in the substrate form a set of initial flaws that leads to complete fracture through the sapphire during cooling for sufficiently thick films. Each stage of this cracking behavior is well described by a fracture mechanics model that delineates a series of critical thicknesses for the onset of cracking that are functions of the film and substrate stresses, thicknesses, and elastic properties. Similar cracking behavior is found to occur independently of the choice of substrate between sapphire and SiC and is traced to a tensile stress generation mechanism early in the growth process, such as that provided by island coalescence. Cracking is the dominant stress relief mechanism, as opposed to dislocation generation or diffusion, because of the island growth mode and because of optimized growth temperatures at or below the brittle-to-ductile transition. Lateral epitaxial overgrowth (LEO) of GaN is shown to minimize substrate fracture even though film cracking remains unaffected. This effect explained in terms of the limits placed on the initial extent of insipient substrate cracks due to the LEO geometry.
Pediatric vascular access

Pediatric interventional radiologists are ideally suited to provide vascular access services to children because of inherent safety advantages and higher success from using image-guided techniques. The performance of vascular access procedures has become routine at many adult interventional radiology practices, but this service is not as widely developed at pediatric institutions. Although interventional radiologists at some children's hospitals offer full-service vascular access, there is little or none at others. Developing and maintaining a pediatric vascular access service is a challenge. Interventionalists skilled in performing such procedures are limited at pediatric institutions, and institutional support from clerical staff, nursing staff, and technologists might not be sufficiently available to fulfill the needs of such a service. There must also be a strong commitment by all members of the team to support such a demanding service. There is a slippery slope of expected services that becomes steeper and steeper as the vascular access service grows. This review is intended primarily as general education for pediatric radiologists learning vascular access techniques. Additionally, the pediatric or adult interventional radiologist seeking to expand services might find helpful tips. The article also provides education for the diagnostic radiologist who routinely interprets radiographs containing vascular access devices.
Nickel-Catalyzed Rearrangement of 1-Acyl-2-vinylcyclopropanes. A Mild Synthesis of Substituted Dihydrofurans

Mild Ni(0)-catalyzed rearrangements of 1-acyl-2-vinylcyclopropanes have been developed. The room-temperature isomerizations afford dihydrofuran products in yields regularly greater than 90%. A highly substituted, stereochemically defined cyclopropane was employed in the rearrangement to evaluate the reaction mechanism. Product analysis indicates that the overall reaction proceeds with retention of configuration at the vinyl-bearing stereogenic center.
Fast Distributed Algorithms for Computing Separable Functions

The problem of computing functions of values at the nodes in a network in a fully distributed manner, where nodes do not have unique identities and make decisions based only on local information, has applications in sensor, peer-to-peer, and ad hoc networks. The task of computing separable functions, which can be written as linear combinations of functions of individual variables, is studied in this context. Known iterative algorithms for averaging can be used to compute the normalized values of such functions, but these algorithms do not extend, in general, to the computation of the actual values of separable functions. The main contribution of this paper is the design of a distributed randomized algorithm for computing separable functions. The running time of the algorithm is shown to depend on the running time of a minimum computation algorithm used as a subroutine. Using a randomized gossip mechanism for minimum computation as the subroutine yields a complete fully distributed algorithm for computing separable functions. For a class of graphs with small spectral gap, such as grid graphs, the time used by the algorithm to compute averages is of a smaller order than the time required by a known iterative averaging scheme.
Memory on the racetrack

Racetrack memory stores digital data in the magnetic domain walls of nanowires. This technology promises to yield information storage devices with high reliability, performance and capacity.
The rings of saturn: A frost-coated semiconductor?

Abstract Optical complex indices of refraction for the iron-sulfur semiconductors troilite and pyrrhotite have been measured between 0.3 and 1.1 μm, and at 1.5 and 3.0 cm in the microwave region. The behavior of the absorptive and refractive components of the index in the visual and ultraviolet regions suggests a reasonable match to published data on Saturn's rings. A combination of the iron sulfur with water ice and the orthopyroxene enstatite is consistent with an equilibrium condensation model for the formation of the solar system; the water ice and an orthopyroxene are also suggested by near-infrared observational data. A combination of these materials could explain all spectral features seen in the ring spectra to date. The microwave behavior of a small quantity of troilite embedded in water ice at low temperatures is consistent with the radar reflectivity and radio emissivity data.
Optimal heading change with minimum energy loss for a hypersonic gliding vehicle

A three state model is presented for analyzing the problem of optimal changes in heading with minimum energy loss for a hypersonic gliding vehicle. A further model order reduction to a single state model is examined using singular perturbation theory. The optimal solution for the reduced problem defines an optimal altitude profile dependent on the current energy of the vehicle, and the corresponding optimal lift and bank angle. A separate boundary layer analysis, based on an expansion of the necessary conditions about the reduced solution, is used to account for altitude and flight path angle dynamics and to derive a guidance law in feedback form. The guidance law is evaluated for a hypothetical vehicle.
Influence of biopsy on the prognosis of cutaneous melanoma of the head and neck.

Background This study was performed to determine the effect of biopsy type on survival rates and on local, regional, and distant metastasis in patients with head and neck cutaneous melanoma. Methods A case series of 159 patients with melanoma of the head and neck referred to a tertiary-care center between 1983 and 1991, with a median follow-up of 38 months, was reviewed. Information analyzed included patient's age, sex, type of treatment, mode of biopsy, presence of residual melanoma in re-excision, location of lesion, presence of ulceration, Clark's level, Breslow thickness, and histologic type of the melanoma. Results Excisional biopsy was performed in 79 patients, incisional biopsy in 48, and other procedures (shave, needle biopsy, cauterization, or cryotherapy) in 32. There were no significant pretreatment differences among the three groups in sex, thickness, histologic type, presence of nodal disease, or type of treatment. Pretreatment location of lesion was significantly different (p = .03) between the excisional and other biopsy types. Association between type of biopsy and survival rate was significant (p < .001): 31.3% of patients in the incisional biopsy group died of disease, as did 25% of the other biopsy group, versus 8.9% of the excisional biopsy group; 31.3% of patients in the incisional biopsy group developed distant metastases, as did 28.1% of the other biopsy type, versus 10.1% of those in the excisional biopsy group (p = .01). There was no significant difference in local p = .37) or regional (p = 1.00) recurrence among the three biopsy groups. Multivariate analysis showed presence of tumor in the re-excision specimen, biopsy type, and nodal disease to be independent prognostic factors. Conclusions Our study suggests that the type of biopsy of cutaneous melanoma of the head and neck may influence the clinical outcome. HEAD & NECK 1996;18:107–117 © 1996 John Wiley & Sons, Inc.
Nonlinear Propagation of Light in One-Dimensional Periodic Structures

We consider the nonlinear propagation of light in an optical fiber waveguide as modeled by the anharmonic Maxwell-Lorentz equations (AMLE). The waveguide is assumed to have an index of refraction that varies periodically along its length. The wavelength of light is selected to be in resonance with the periodic structure (Bragg resonance). The AMLE system considered incorporates the effects of noninstantaneous response of the medium to the electromagnetic field (chromatic or material dispersion), the periodic structure (photonic band dispersion), and nonlinearity. We present a detailed discussion of the role of these effects individually and in concert. We derive the nonlinear coupled mode equations (NLCME) that govern the envelope of the coupled backward and forward components of the electromagnetic field. We prove the validity of the NLCME description and give explicit estimates for the deviation of the approximation given by NLCME from the exact dynamics, governed by AMLE. NLCME is known to have gap soliton states. A consequence of our results is the existence of very long-lived gap soliton states of AMLE. We present numerical simulations that validate as well as illustrate the limits of the theory. Finally, we verify that the assumptions of our model apply to the parameter regimes explored in recent physical experiments in which gap solitons were observed.
Key aspects of coronal heating

We highlight 10 key aspects of coronal heating that must be understood before we can consider the problem to be solved. (1) All coronal heating is impulsive. (2) The details of coronal heating matter. (3) The corona is filled with elemental magnetic stands. (4) The corona is densely populated with current sheets. (5) The strands must reconnect to prevent an infinite build-up of stress. (6) Nanoflares repeat with different frequencies. (7) What is the characteristic magnitude of energy release? (8) What causes the collective behaviour responsible for loops? (9) What are the onset conditions for energy release? (10) Chromospheric nanoflares are not a primary source of coronal plasma. Significant progress in solving the coronal heating problem will require coordination of approaches: observational studies, field-aligned hydrodynamic simulations, large-scale and localized three-dimensional magnetohydrodynamic simulations, and possibly also kinetic simulations. There is a unique value to each of these approaches, and the community must strive to coordinate better.
The jackknife procedure for the probabilities of misclassification

Seven estimators for the probabilities of misclassification associated with the linear discriminant function are considered. Four of them are known in the literature. The remaining three are constructed through the Jackknife Procedure. An empirical investigation is conducted to evaluate the relative merits of these estimators. Summary of the results is presented.
Blame, Cause, and Counterfactuals: The Inextricable Link

In the target article “A Theory of Blame,” Malle, Guglielmo, and Monroe (this issue) set out their multistage Path Model for how people assign blame to individuals for the consequences of their act...
D6 branes and M theory geometrical transitions from gauged supergravity

We study the supergravity duals of supersymmetric theories arising in the world-volume of D6-branes wrapping holomorphic two-cycles and special lagrangian three-cycles within the framework of eight-dimensional gauged supergravity. When uplifted to 11d, our solutions represent M-theory on the background of, respectively, the small resolution of the conifold and a manifold with G2 holonomy. We further discuss on the flop and other possible geometrical transitions and its implications.
An X-ray scattering and simulation study of the ordering kinetics in CuAu

A detailed numerical and experimental study of the ordering of the low-temperat ure tetragonal phase of CuAu is presented. The numerical simulations are based on a coarse-grained free energy derived from electronic structure calculations of CuAu, while the experimental results are obtained from in situ X-ray scattering. Both theoretical and experimental work indicate a subtle kinetic competition between the ordered tetragonal phase and the metastable modulated phase.
B2FH, the Cosmic Microwave Background and Cosmology

In this talk I shall start by describing how we set about and carried out the work that led to the publication of Burbidge et al. (1957, hereafter B2FH). I then shall try and relate this work and the circumstances that surrounded it to the larger problem of the origin and formation of the universe. Here it is necessary to look back at the way that ideas developed and how, in many situations, astronomers went astray. Of course this is a personal view, though I very strongly believe that if he were still here, it is the approach that Fred Hoyle would take. I start by describing the problems originally encountered by Gamow and his associates in trying to decide where the helium was made. This leads me to a modern discussion of the origin of 2D, 3He, 4He and 7Li, originally described by B2FH as due to the x-process. While it is generally argued, following Gamow, Alpher, and Herman, that these isotopes were synthesised in a big bang I shall show that it is equally likely that these isotopes were made in active galactic nuclei, as was the cosmic microwave background (CMB), in a cyclic universe model. The key piece of observational evidence is that the amount of energy released in the conversion of hydrogen to helium in the universe is very close to the energy carried by the CMB, namely ~4.5 × 10–13 erg cm–3.
The molecular basis of moisture effects on the physical and chemical stability of drugs in the solid state

It is well recognized that residual water associated with drugs in the solid state can have significant effects on a variety of physical and chemical properties, such as chemical degradation, dissolution rate, flow and compactibility. In this brief review, emphasis will be placed on the role of water in affecting drug entities that are believed to exist predominantly in the crystalline state, in the absence and presence of excipients and other drugs in the formulation.
Assessing Alternative Proxies for the Expected Risk Premium

Managers, investors, and researchers have a compelling interest in identifying a reliable empirical proxy for firm‐specific cost of equity capital (r). In theory, deducing r is possible if the market's future cash flow forecast and current stock price are observable. Practically, deducing r is dependent on the ability to estimate the market's forecasted terminal value. We evaluate five methods of deducing firm‐specific r (labeled rDIVPREM, rGLSPREM, rGORPREM, rOJNPREM, and rPEGPREM) that deal with this conundrum differently. The extent to which the estimates are associated with firm risk in a stable and meaningful manner is the basis for our assessment. We find that the rDIVPREM and rPEGPREM estimates are consistently and predictably related to risk, while the alternatives are not. Based on these results, we conclude that rDIVPREM and rPEGPREM dominate the alternatives.
Weak non-mesonic decays of Λ-hypernuclei

Abstract We review the current status of studies of weak non-mesonic decays of Λ-hypernuclei. Both experimental and theoretical aspects are reviewed. Experimental results obtained during the last thirty years are discussed, including the recent studies of weak decays of hypernuclei at Brookhaven. The current (unsatisfactory) theoretical understanding of the subject is analysed, following the various approaches in the pertinent literature. For the most part, available treatments are based on the two-body Λ + N → N + N weak interaction as the underlying non-mesonic decay mechanism. However this may not be the appropriate starting point. Starting with the phenomenological approach of Dalitz et al. and continuing with a description of microscopic models suggested for the Λ + N → N + N interaction, we review over thirty years of theoretical efforts. The need for new and improved data is pointed out.
Do We Know of Any Maunder Minimum Stars

Most stars previously identified as Maunder minimum stars are old and evolved off the main sequence. Analysis of activity measurements from the California and Carnegie Planet Search program stars and Hipparcos parallaxes implies that the canonical relation between age and chromospheric activity breaks down for stars older than ~6 Gyr when activity is calculated from Mount Wilson S-values. Stars only 1 mag above the main sequence exhibit significantly suppressed activity levels, which have been mistaken for examples of Maunder minimum behavior.
New Symmetries of Massless QED

An infinite number of physically nontrivial symmetries are found for abelian gauge theories with massless charged particles. They are generated by large U(1) gauge transformations that asymptotically approach an arbitrary function "(z, ¯ z) on the conformal sphere at future null infinity (I + ) but are independent of the retarded time. The value of " at past null infinity (I − ) is determined from that on I + by the condition that it take the same value at either end of any light ray crossing Minkowski space. The " 6 constant symmetries are spontaneously broken in the usual vacuum. The associated Goldstone modes are zero-momentum photons and comprise a U(1) boson living on the conformal sphere. The Ward identity associated with this asymptotic symmetry is shown to be the abelian soft photon theorem.
The apollo telescope mount on skylab

Abstract The Apollo Telescope Mount on Skylab, launched into Earth orbit on May 14, 1973, as the first manned solar observatory in space, has provided a major advance in our knowledge about the Sun. In addition to solar physics research, it explored the advantages and limitations of man as an observer and operator of a major scientific spacecraft, and provided concepts for potential application to future space programs. The ATM contained eight solar telescopes and provided these instruments with the necessary pointing reference and control, electrical power, thermal control, and telemetry and command links. Additionally, the experiments and supporting systems were integrated with the necessary controls and displays to permit complete operation and control by the astronaut crew. The ATM, during the nearly nine-month mission, provided data from the experiments which exceeded the pre-mission expectations in terms of quality, quantity, and the spectrum of observed solar activity. Areas of potentially significant new scientific findings included rapid large scale changes in the corona, flare trigger mechanisms and energy relationships, coronal holes and their relationship to solar wind, and the existence of numerous bright spots in the X-ray corona. Thorough analysis of the vast amount of data returned will require several years, but the indications to date are that the mission has provided extremely valuable scientific information which will probably result in significant changes to the currently accepted solar model.
Nigeria's Infrastructure : A Continental Perspective

Infrastructure has made a net contribution of around one percentage point to Nigeria's improved per capita growth performance in recent years, in spite of the fact that unreliable power supply held growth back. Raising the country's infrastructure endowment to that of the region's middle-income countries could boost annual growth by around four percentage points. Nigeria has made important strides toward improving much of its infrastructure. Compared to many African peers, Nigeria has relatively advanced power, road, rail, and information and communications technology (ICT) networks that cover extensive areas of the nation's territory. In recent years, Nigeria has conducted several important infrastructure sector reforms. The ports sector has been converted to a landlord model, and terminal concessions now attract private investment on a scale unprecedented for Africa. The power sector is undergoing a restructuring, paving the way for performance improvements; the sector is finally on a path toward raising tariffs to recover a larger share of costs. Bold liberalization measures in the ICT sector have resulted in widespread, low-cost mobile services, Africa's most vibrant fixed-line sector, and major private investments in the development of a national fiber-optic backbone. A burgeoning domestic air transport sector has emerged, with strong private carriers that have rapidly attained regional significance.
Reading, writing, and religion: Institutions and human capital formation

Abstract In this paper, we empirically test the role that religious and political institutions play in the accumulation of human capital. Using a new data set on literacy in colonial India, we find that Muslim literacy is negatively correlated with the proportion of Muslims in the district, although we find no similar result for Hindu literacy. We employ a theoretical model which suggests that districts which experienced a more recent collapse of Muslim political authority had more powerful and better funded religious authorities, who established religious schools which were less effective at promoting literacy on the margin than state schools. We test this hypothesis econometrically, finding that the period of Muslim political collapse has a statistically significant effect on Muslim literacy while controlling for it eliminates the significance of the proportion of Muslims on Muslim literacy. This suggests that the “long hand of history” has played some role in subsequent differences in human capital formation through the persistence of institutions discouraging literacy.
Precipitation Variability over the Forest-to-Nonforest Transition in Southwestern Amazonia

AbstractPrior research has shown that deforestation in the southwestern Amazon enhances the formation of nonprecipitating shallow cumulus clouds, while deep cumulus convection was favored over forested land. The research presented here further investigates the trends of hydrometeors in the area by examining how precipitation frequency changes as a function of distance to the forest’s edge. Measurements are made from the precipitation radar on the Tropical Rainfall Measuring Mission (TRMM; TRMM 2A25) satellite, and continuous forest coverage is retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS; MODIS MCD12Q1). The event-based areal fractions of precipitation coverage (precipitation fraction) are calculated; referenced to forested, nonforested, and forest-edge land cover; and compared. As results are generally consistent with previous findings, the novel conclusions here extend that precipitation frequency in the southwestern Amazon (i) decreases over regions of nonforests far removed ...
Results of the Pollution Reduction Technology Program for Turboprop Engines

A program was performed to evolve and demonstrate advanced combustor technology aimed at achieving the 1979 EPA standards for turboprop engines (Class P2). The engine selected for this program was the 501-D22A turboprop manufactured by Detroit Diesel Allison Division of General Motors Corporation. Three combustor concepts were designed and tested in a combustor rig at the exact combustor operating conditions of the 501-D22A engine over the EPA landing-takeoff cycle. Each combustor concept exhibited pollutant emissions well below the EPA standards, achieving substantial reductions in unburned hydrocarbons, carbon monoxide, and smoke emissions compared with emissions from the production combustor of this engine. Oxides of nitrogen emissions remained well below the EPA standards, also.
Influence of confinement on dynamical heterogeneities in dense colloidal samples

We study a dense colloidal suspension confined between two quasiparallel glass plates as a model system for a supercooled liquid in confined geometries. We directly observe the three-dimensional Brownian motion of the colloidal particles using laser scanning confocal microscopy. The particles form dense layers along the walls, but crystallization is avoided as we use a mixture of two particle sizes. A normally liquidlike sample, when confined, exhibits slower diffusive motion. Particle rearrangements are spatially heterogeneous, and the shapes of the rearranging regions are strongly influenced by the layering. These rearranging regions become more planar upon confinement. The wall-induced layers and changing character of the spatially heterogeneous dynamics appear strongly connected to the confinement-induced glassiness.
WOVEN FABRIC COMPOSITES: DEVELOPMENTS IN ENGINEERING BOUNDS, HOMOGENIZATION AND APPLICATIONS

Various approaches for approximating upper and lower bounds for the elastic stiffness tensor for general woven fabric composites are first described. Well accepted minimum energy principles are briefly presented to establish the foundation for practical finite element procedures for determining these bounds. Secondly, comparisons of four common homogenization procedures are shown: the strain energy balance method, the plate approximation method, a direct approach via area averaging, and asymptotic expansion homogenization. As a limiting case, all of the methods obtain the well-known Rule of Mixtures for a unidirectional uniaxial specimen. In attempting to consolidate much of the existing knowledge of structural constitutive models for woven fabric composites, this research seeks to summarize and compare various homogenization methods via finite element analyses. Finally, some illustrative applications are presented. Copyright © 1999 John Wiley & Sons, Ltd.
Optimal fiscal and monetary policy in an economy without capital

Abstract This paper is concerned with the structure and time-consistency of optimal fiscal and monetary policy in an economy without capital. In a dynamic context, optimal taxation means distributing tax distortions over time in a welfare-maximizing way. For a barter economy, our main finding is that with debt commitments of sufficiently rich maturity structure, an optimal policy, if one exists, is time-consistent. In a monetary economy, the idea of optimal taxation must be broadened to include an ‘inflation tax’, and we find that time-consistency does not carry over. An optimal ‘inflation tax’ requires commitment by ‘rules’ in a sense that has no counterpart in the dynamic theory of ordinary excise taxes. The reason time-consistency fails in a monetary economy is that nominal assets should, from a welfare-maximizing point of view, always be taxed away via an immediate inflation in a kind of ‘capital levy’. This emerges as a new possibility when money is introduced into an economy without capital.
Indirect processes in electron impact ionization of multiply-charged ions

Abstract Recent research efforts have assembled a steadily increasing array of measurements and calculations of electron impact ionization of multiply-charged ions. Significant disagreement is often found, however, between experimental results and theory due to the influence of a number of indirect processes observed in the experiments but not included in the calculations. Some of the most important of these indirect ionization processes are described and examples are discussed. New data for electron impact single-ionization of Kr2+ are presented in the energy range from below threshold (36 eV) to 1500 eV, and compared with related measurements and with theory.
Complementarity of quantum discord and classically accessible information

The sum of the Holevo quantity (that bounds the capacity of quantum channels to transmit classical information about an observable) and the quantum discord (a measure of the quantumness of correlations of that observable) yields an observable-independent total given by the quantum mutual information. This split naturally delineates information about quantum systems accessible to observers – information that is redundantly transmitted by the environment – while showing that it is maximized for the quasi-classical pointer observable. Other observables are accessible only via correlations with the pointer observable. We also prove an anti-symmetry property relating accessible information and discord. It shows that information becomes objective – accessible to many observers – only as quantum information is relegated to correlations with the global environment, and, therefore, locally inaccessible. The resulting complementarity explains why, in a quantum Universe, we perceive objective classical reality while flagrantly quantum superpositions are out of reach.
X- or γ-ray leukemogenesis in humans

A calculation of the probability of X-ray or gamma-ray leukemogenesis per cell in humans is made. It is assumed that the theory is of the two-hit type. The first hit damages DNA repair capability of base damage. The second hit causes derepression of a 2 repressor system. Sequential repression of gene expression occurs. Inactivation of the first repressor permits synthesis of the second which will repress the expression of the leukocyte maturation gene. The first repressor is inactivated by X-ray damage to its corresponding operator region. I have used a more realistic value of immune efficiency for the bone marrow and I have considered spontaneous leukemogenesis. Agreement with the best algebraic fit of Kellerer and Rossi for the Nagasaki victims is good.
A cognitive model for structuring an introductory programming curriculum

From its inception the electronic digital computer has been involved in education, although its role has been the subject of some debate. Academically, the computer has been used as a device for conducting or augmenting instruction, as a calculating device adjunctive to courses in engineering and the sciences, and most recently as an object for study in its own right. Increasing attention is now being focused on undergraduate training in computer use, partly as a result of the recommendation of the President's Science Advisory Committee that computing education be provided to all college undergraduates. We can expect that the number of students who undertake incidental study of programming as a part of their undergraduate curricula will continue to increase rapidly.
Dissipation in relativistic pair-plasma reconnection

An investigation into the relativistic dissipation in magnetic reconnection is presented. The investigated system consists of an electron-positron plasma. A relativistic generalization of Ohm’s law is derived. A set of numerical simulations is analyzed, composed of runs with and without guide magnetic field, and of runs with different species temperatures. The calculations indicate that the thermal inertia-based dissipation process survives in relativistic plasmas. For antiparallel reconnection, it is found that the pressure tensor divergence remains the sole contributor to the reconnection electric field, whereas relativistic guide field reconnection exhibits a similarly important role of the bulk inertia terms.
On groups with locally compact asymptotic cones

We show how a recent result of Hrushovsky [Stable group theory and approximate subgroups, J. Amer. Math. Soc.25(1) (2012) 189–243] implies that if an asymptotic cone of a finitely generated group is locally compact, then the group is virtually nilpotent.
A latent class procedure for the structural analysis of two-way compositional data

This paper develops a new procedure for simultaneously performing multidimensional scaling and cluster analysis on two-way compositional data of proportions. The objective of the proposed procedure is to delineate patterns of variability in compositions across subjects by simultaneously clustering subjects into latent classes or groups and estimating a joint space of stimulus coordinates and class-specific vectors in a multidimensional space. We use a conditional mixture, maximum likelihood framework with an E-M algorithm for parameter estimation. The proposed procedure is illustrated using a compositional data set reflecting proportions of viewing time across television networks for an area sample of households.
The outpatient evaluation of hematochezia

Objective: The objective of this study was to determine whether specific clinical symptoms associated with hematochezia are predictive of important GI pathology and whether full colonoscopic examination is necessary. Methods: A total of 103 outpatients (≥ 45 yr) with hematochezia, defined as the passage of bright red blood per rectum, underwent anoscopy and colonoscopy. Before endoscopy, patients completed a detailed interview, quantitating the amount and frequency of bleeding, weight loss, use of aspirin/NSAIDs, change in bowel habits, family history, and prior GI illnesses. Based on this information, physicians were asked to predict whether the bleeding was from a perianal or more proximal site. At colonoscopy, pathology was stratified as either proximal or distal to the sigmoid/descending junction. Substantial pathology was defined as one or more adenomas > 8 mm, carcinoma, or colitis. Results: Anoscopy demonstrated internal and external hemorrhoids in 78 and 29 patients, respectively. On colonoscopy, 36 patients had 43 substantial lesions. Thirty-seven of these lesions were distal to the junction of the descending and sigmoid colons and six were proximal lesions. Four patients had cancer; all were distal lesions. Patients with substantial lesions were more likely to give a history of blood mixed within their stool ( p = 0.03), to have more episodes of hematochezia per month ( p = 0.008), and to have a significantly shorter duration of bleeding before medical evaluation ( p = 0.02) than did patients without such lesions. However, the physician's clinical assess- ment did not predict reliably which patients were likely to have substantial pathology. Conclusions: In patients with hematochezia, clinicians were unable to distinguish between those patients with and those without significant colonic lesions by history alone. Flexible sigmoidoscopy would have demonstrated most (95%) substantial lesions. The lesions that flexible sigmoidoscopy missed were an unlikely cause of bleeding in this small group of patients.