cssi/SciSciGPT-SciSciNet huggingface dataset:
The Compilation of Regular Expressions into Integrated Circuits

Abstract : We consider the design of integrated circuits to implement arbitrary regular expressions. In general, we may use the McNaughton-Yamada algorithm to convert a regular expression of length n into a nondeterministic finite automation with at most 2n states and 4n transitions. Instead of converting the nondeterministic device to a deterministic one, we propose two ways of implementing the nondeterministic device directly. First, we could produce a PLA (programmable logic array) of approximate dimensions 4n x 4n by representing the states directly by columns, rather than coding the states in binary. This approach, while theoretically suboptimal, makes use of carefully developed technology and, because of the care with which PLA implementation has been done, may be the preferred technique in many real situations. Another approach is to use the hierarchical structure of the automation produced from the regular expression to guide a hierarchical layout of the circuit. This method produces a circuit 0(square root of n) on a side and is, to within a constant factor, the best that can be done in general. (Author)
Beam Amplification by Transient Energy Transfer in GaAs and Si

Two beam coupling experiments with 29-ps (FWHM) pulses at a wavelength of 1.06 μm have been performed in GaAs and Si. By optimization of pump-probe energy ratio, time delay and fluence we obtained optical gain up to 25 in GaAs at a fluence of 35 mJ/cm2 compared to roughly 140 mJ/cm2 required to obtain similar gain in Si. Nous avons realise une experience de couplage a deux ondes sur GaAs et Si avec des impulsions de 29 ps (FWHM) a 1,06 μm. En optimisant le rapport pompe-sonde, le retard entre les impulsions et le flux d'energie nous avons mesure un gain de 25 avec GaAs pour un flux d'energie de 35 mJ/cm2 alors que, approximativement 140 mJ/cm2 sont necessaires pour obtenir un gain similaire avec Si.
Understanding a War That Is Not a War: A Review Essay

Writing in 1944 in occupied France, Gertrude Stein observed: “It is funny about wars, they ought to be different but they are not” (1945, 11). Exactly what she meant to convey, I am still not completely certain. But it is this very uncertainty, accentuated by Stein’s disquieting refusal to directly consider the war beyond its effects on her “habits” of daily life, that makes this phrase so plangent (Olson 2003, 341).1 It throws into relief how our judgments about war, and about those who mediate war’s distortions of daily life, are as fraught and open to critical contention as are Stein herself, her writings, and her actions. To consider the meaning of her phrase — wars ought to be different, but they are not — the questions that it raises, and the habits of understanding it disturbs, is one mode of reading eight recent texts about war, violence, and security.
Stretchable electronics: Materials strategies and devices

New electronic materials have the potential to enable wearable computers, personal health monitors, wall-scale displays and other systems that are not easily achieved with established wafer based technologies. A traditional focus of this field is on the development of materials for circuits that can be formed on bendable substrates, such as sheets of plastic or steel foil. More recent efforts seek to achieve similar systems on fully elastic substrates for electronics that can be stretched, compressed, twisted and deformed in ways that are much more extreme than simple bending. This article highlights some recent progress in this area, with an emphasis on materials approaches and demonstrated devices.
Kontsevich–Witten model from 2+1 gravity: new exact combinatorial solution

Abstract In previous publications [J. Geom. Phys. 38 (2001) 81 and references therein] the partition function for 2+1 gravity was constructed for the fixed genus Riemann surface. With the help of this function the dynamical transition from pseudo-Anosov to periodic (Seifert-fibered) regime was studied. In this paper the periodic regime is studied in some detail in order to recover major results of Kontsevich [Commun. Math. Phys. 147 (1992) 1] inspired by earlier work of Witten on topological two-dimensional quantum gravity. To achieve this goal some results from enumerative combinatorics have been used. The logical developments are extensively illustrated using geometrically convincing figures. This feature is helpful for development of some nontraditional applications (mentioned through the entire text) of obtained results to fields other than theoretical particle physics.
On Scheduling Independent Tasks with Restricted Execution Times

We consider the problem of nonpreemptively scheduling n independent tasks on m identical and parallel machines with the objective of minimizing the overall finishing time. The problem has been shown to be NP-complete in the strong sense and hence there probably will not be any pseudopolynomial time algorithm for solving this problem. We show, however, that if the execution times are restricted to a fixed number, say k, of different values, then it can be solved in polynomial time. Our algorithm can be implemented to run in time 0log2p * log2m * n2k-1 and space 0log2m * nk-1 in the worst case, where p is the largest execution time.
Existence of double vortex solutions

Abstract We show analytically and numerically the existence of double vortex solutions in two-Higgs systems. These solutions are generalizations of the Nielsen-Olesen vortices and exist for all values of the parameters in the Lagrangians considered. We derive analytically the asymptotic behavior of the solutions and confirm it numerically by solving the field equations. Finally, we show that these solutions can be embedded in realistic theories like the two-doublet extension of the standard model.
On Weakly Null FDD's in Banach Spaces

In this paper we show that every sequence (F n ) of finite dimensional subspaces of a real or complex Banach space with increasing dimensions can be “refined” to yield an F.D.D. (G n ), still having increasing dimensions, so that either every bounded sequence (x n ), withx n ∈G n forn∈ℕ, is weakly null, or every normalized sequence (x n ),withx n ∈G n forn∈ℕ, is equivalent to the unit vector basis of l1. Crucial to the proof are two stabilization results concerning Lipschitz functions on finite dimensional normed spaces. These results also lead to other applications. We show, for example, that every infinite dimensional Banach spaceX contains an F.D.D. (F n ),with lim n→∞dim(F n )=∞, so that all normalized sequences (x n ),withx n ∈F n ,n∈∕, have the same spreading model overX. This spreading model must necessarily be 1-unconditional overX.
Hydride reagents for stereoselective reductive amination. An improved preparation of 3-endo-tropanamine

Abstract The reductive amination of substituted cyclohexanones with sodium triacyloxy-borohydrides derived from NaBH 4 and various carboxylic acids provides highly diastereoselective conversions to protected axial amines. This method was applied to the stereoselective preparation of 3-endo-tropanamine.
Temporally inhomogeneous nonlinear scattering theory

Abstract This paper considers scattering theory for a pair of time dependent nonlinear evolution equations. Sufficient conditions are given for the existence of the forward wave operators. An approximation theory for the forward wave operators is also developed.
Synthesis of polycyclic aromatic fluoranthenes

Abstract A general synthetic approach to polycyclic aromatic hydrocarbons containing a fluoranthene ring system is described. The method entails fusion of an indeno ring to an alternant hydrocarbon via reaction of an aryllithium derivative with cyclohexene oxide.
Linear transceiver design for a MIMO interfering broadcast channel achieving max–min fairness

Abstract We consider the problem of linear transceiver design to achieve max–min fairness in a downlink MIMO multicell network. This problem can be formulated as maximizing the minimum rate among all the users in an interfering broadcast channel (IBC). In this paper we show that when the number of antennas is at least two at each of the transmitters and the receivers, the min rate maximization problem is NP-hard in the number of users. Moreover, we develop a low-complexity algorithm for this problem by iteratively solving a sequence of convex subproblems. We theoretically establish the global convergence of the proposed algorithm to the set of stationary points, which may be suboptimal due to the non-convexity of the original minimum rate maximization problem. Numerical simulations show that this algorithm is efficient in achieving fairness among all the users.
Scalable Similarity Learning Using Large Margin Neighborhood Embedding

Classifying large-scale image data into object categories is an important problem that has received increasing research attention. Given the huge amount of data, non-parametric approaches such as nearest neighbor classifiers have shown promising results, especially when they are underpinned by a learned distance or similarity measurement. Although metric learning has been well studied in the past decades, most existing algorithms are impractical to handle large-scale data sets. In this paper, we present an image similarity learning method that can scale well in both the number of images and the dimensionality of image descriptors. To this end, similarity comparison is restricted to each sample's local neighbors and a discriminative similarity measure is induced from large margin neighborhood embedding. We also exploit the ensemble of projections so that high-dimensional features can be processed in a set of lower-dimensional subspaces in parallel. The efficiency and scalability of our proposed model are validated on several data sets with scales varying from tens of thousands to one million images.
Retirement and Consumption in a Life Cycle Model

Consumption expenditure declines sharply at the time of retirement for many households, but the majority maintain a smooth consumption path. A simple life cycle model with uncertainty about the time of retirement can account for this pattern. A richer version of the model is calibrated to data from the Health and Retirement Study (HRS). The median change in consumption expenditure at retirement generated by the model is zero, while the mean is negative, matching the HRS data. However, the magnitude of the drop in consumption among households that experience a decline is too small in the model compared to the data.
THE EFFECTS OF PATCHY REIONIZATION ON SATELLITE GALAXIES OF THE MILKY WAY

We combine the high-resolution Aquarius simulations with three-dimensional models of reionization based on the initial density field of the Aquarius parent simulation, Millennium-II, to study the impact of patchy reionization on the faint satellite population of Milky Way halos. Because the Aquarius suite consists of zoom-in simulations of halos in the Millennium-II volume, we follow the formation of substructure and the growth of reionization bubbles due to the larger environment simultaneously, and thereby determine the reionization redshifts of satellite candidates. We do this for four different reionization models and also compare results to instantaneous reionization. Using a simple procedure for selecting satellites and assigning luminosities in the simulations, we compare the resulting satellite populations. We find that the overall number of satellites depends sensitively on the reionization model, with a factor of 3-4 variation between the four models for a given host halo, although the difference is entirely in the population of faint satellites (MV > –10). In addition, we find that for a given reionization model the total number of satellites differs by 10%-20% between the patchy and homogeneous scenarios, provided that the redshift is chosen appropriately for the instantaneous case. However, the halo-halo scatter from the six Aquarius halos is large, up to a factor of 2-3, and so is comparable to the difference between reionization scenarios. In order to use the population of faint dwarf galaxies around the Milky Way as a probe of the local reionization history, it is necessary to first better understand the general distribution of substructure around Milky Way-mass halos.
Nucleation and the Transition State of the SH3 Domain

We present a verified computational model of the SH3 domain transition state (TS) ensemble. This model was built for three separate SH3 domains using experimental phi-values as structural constraints in all-atom protein folding simulations. While averaging over all conformations incorrectly considers non-TS conformations as transition states, quantifying structures as pre-TS, TS, and post-TS by measurement of their transmission coefficient ("probability to fold", or p(fold)) allows for rigorous conclusions regarding the structure of the folding nucleus and a full mechanistic analysis of the folding process. Through analysis of the TS, we observe a highly polarized nucleus in which many residues are solvent-exposed. Mechanistic analysis suggests the hydrophobic core forms largely after an early nucleation step. SH3 presents an ideal system for studying the nucleation-condensation mechanism and highlights the synergistic relationship between experiment and simulation in the study of protein folding.
Enantioselective Synthesis of α-Oxy Amides via Umpolung Amide Synthesis

α-Oxy amides are prepared through enantioselective synthesis using a sequence beginning with a Henry addition of bromonitromethane to aldehydes and finishing with Umpolung Amide Synthesis (UmAS). Key to high enantioselection is the finding that ortho-iodo benzoic acid salts of the chiral copper(II) bis(oxazoline) catalyst deliver both diastereomers of the Henry adduct with high enantiomeric excess, homochiral at the oxygen-bearing carbon. Overall, this approach to α-oxy amides provides an innovative complement to alternatives that focus almost entirely on the enantioselective synthesis of α-oxy carboxylic acids.
Conductors of wild extensions of local fields, especially in mixed characteristic (0,2)

If K_0 is the fraction field of the Witt vectors over an algebraically closed field k of characteristic p, we calculate upper bounds on the conductor of higher ramification for (the Galois closure of) extensions K_0(zeta_{p^r}, sqrt[p^r]{a})/K_0, where a is in K_0(zeta_{p^r}). Here zeta_{p^r} is a primitive p^r-th root of unity. In certain cases, including when a is in K_0 and p=2, we calculate the conductor exactly. These calculations can be used to determine the discriminants of various extensions of Q obtained by adjoining roots of unity and radicals.
Synthesis of acyloxyalkyl acylphosphonates as potential prodrugs of the antiviral, trisodium phosphonoformate (foscarnet sodium)

Abstract Bis(trimethylsilyl) acylphosphonates via their silver salts couple with iodoalkyl esters to provide an efficient synthesis of the corresponding acyloxyalkyl esters as potential prodrugs of the antiviral agent, trisodium phosphonoformate. These compounds were tested as inhibitors of HIV-1 in chronically infected H9 cells.
Laser cooling without spontaneous emission using the bichromatic force

It is widely believed that spontaneous emission (SE) is necessary to remove entropy from an atomic sample during laser cooling. In fact, SE is needed for energy removal when laser cooling is done with single-frequency light, but with more than one frequency, both energy and entropy can be removed using only stimulated processes. Our experimental demonstration of this phenomenon works by restricting the atom–light interaction to a time short compared to a cycle of absorption followed by natural decay [Phys. Rev. Lett.114, 043002 (2015)PRLTAO0031-900710.1103/PhysRevLett.114.043002]. We present here additional information on these results, in particular, simulations of the motion of atoms under the bichromatic force that compare well with our data. This accomplishment is of interest to direct laser cooling of molecules or in experiments where working space or time is limited.
Aspherical manifolds with relatively hyperbolic fundamental groups

We show that the aspherical manifolds produced via the relative strict hyperboli- zation of polyhedra enjoy many group-theoretic and topological properties of open finite volume negatively pinched manifolds, including relative hyperbolicity, nonvanishing of simplicial volume, co-Hopf property, finiteness of outer automorphism group, absence of splitting over elementary subgroups, and acylindricity. In fact, some of these properties hold for any compact aspherical manifold with incompressible aspherical boundary components, provided the fundamental group is hyperbolic relative to fundamental groups of boundary components. We also show that no manifold obtained via the relative strict hyperbolization can be embedded into a compact Kahler manifold of the same dimension, except when the dimension is two.
Neurophysiology of sexual response in spinal cord injury.

Commonalities and differences in the neurophysiology of sexual response in persons with spinal cord injuries and the non-cord injured are described. Recognition of individual differences and other implications for sex education and counseling with the spinal cord injured are presented.
Imperfect transparency and shifts in the central bank's output gap target

Abstract In the New Keynesian framework, the public's expectation about the future path of monetary policy is an important determinant of current economic conditions. This paper examines the impact of unobservable shifts in the central bank's output gap target on inflation and output dynamics. I show that when the degree of persistence of a shock is private information of the central bank, and policy is discretionary in nature, it is optimal for the central bank not to reveal the future expected path of the output gap target. Perfect transparency unambiguously increases inflation and output volatility and thus lowers welfare.
Copper catalyzed addition reaction of iododifluoroacetates to olefins

Abstract The addition of iododifluoroacetates to alkenes is catalyzed by copper powder (10-20 mol %) at 50° to 60°C. The reaction can be carried out neat or in hexane or benzene as solvent. Both terminal and internal alkenes gave good yields (65-83%). Reduction of the adduct with tributyltin hydride provides the α, α-difluoroacetate.
On the miscible Rayleigh–Taylor instability: two and three dimensions

We investigate the miscible Rayleigh–Taylor (RT) instability in both two and three dimensions using direct numerical simulations, where the working fluid is assumed incompressible under the Boussinesq approximation. We first consider the case of randomly perturbed interfaces. With a variety of diagnostics, we develop a physical picture for the detailed temporal development of the mixed layer: we identify three distinct evolutionary phases in this development, which can be related to detailed variations in the growth of the mixing zone. Our analysis provides an explanation for the observed differences between two- and three-dimensional RT instability; the analysis also leads us to concentrate on the RT models which (i) work equally well for both laminar and turbulent flows, and (ii) do not depend on turbulent scaling within the mixing layer between fluids. These candidate RT models are based on point sources within bubbles (or plumes) and their interaction with each other (or the background flow). With this motivation, we examine the evolution of single plumes, and relate our numerical results (for single plumes) to a simple analytical model for plume evolution.
Preparation and characterization of Cu(II) oxide

Abstract Copper(II) oxide was prepared by oxidation of copper metal and decomposition of the nitrate. The presence of copper in the formal valence of Cu(III) has been confirmed in p-type CuO. The magnetic and electronic properties have been studied as a function of preparation and annealing conditions.
IS POVERTY INCREASING IN THE DEVELOPING WORLD

The authors assess the developing world's progress in reducing absolute-consumption poverty during 1981-91, using new data on the distribution of household consumption or income per capita for 40 countries (at two points in time for 18 of the countries). They apply dominance tests to the distributions after adjustment to purchasing-power parity. They find that the incidence of aggregate poverty changed little. The number of poor increased at the rate of population growth. The region with the greatest aggregate poverty is either South Asia or sub-Saharan Africa, depending on the poverty line used. The experience was diverse across regions and countries. The only regions with falling poverty measures are South and East Asia.
Design issues in a rule-based system

Abstract This paper discusses the interaction between language, environment and development model in the realm of rulebased systems. In particular, efforts in building a rule-based language and development tools that support incremental development, interactive debugging, and reuse of components are discussed.
Continuous-wave fiber optical parametric oscillator

We report continuous-wave operation of singly resonant fiber optical parametric oscillators. In a cavity formed by 100 m of highly nonlinear fiber and two fiber Bragg gratings, the pump power threshold was 240 mW; the output wavelength could be tuned over 80 nm by tuning of the pump. We also obtained an internal conversion efficiency of 30%, compared with the maximum theoretical value of 50%, by use of a 1-km-long cavity.
The Redshift and the Ordinary Host Galaxy of GRB 970228

The gamma-ray burst of 1997 February 28 (GRB 970228) ushered in the discovery of the afterglow phenomenon. Despite intense study of the nearby galaxy, however, the nature of this galaxy and the distance to the burst eluded the community. Here we present the measurement of the redshift of the galaxy, the putative host galaxy of GRB 970228, and, based on its spectroscopic and photometric properties, identify the galaxy as a subluminous but otherwise normal galaxy at redshift z = 0.695 undergoing a modest level of star formation. At this redshift, the GRB released an isotropic-equivalent energy of (1.4 ± 0.3) × 1052 ergs (20-2000 keV rest frame). We find no evidence that the host is significantly bluer or is forming stars more vigorously than the general field population. In fact, by all accounts in our analysis (color-magnitude, magnitude-radius, star formation rate, and Balmer-break amplitude), the host properties appear typical for faint blue field galaxies at comparable redshifts.
The Addition of Graphene to Polymer Coatings for Improved Weathering

Graphene nanoflakes in different weight percentages were added to polyurethane top coatings, and the coatings were evaluated relative to exposure to two different experimental conditions: one a QUV accelerated weathering cabinet, while the other a corrosion test carried out in a salt spray chamber. After the exposure tests, the surface morphology and chemical structure of the coatings were investigated via atomic force microscopy (AFM) and Fourier transform infrared (FTIR) imaging. Our results show that the addition of graphene does in fact improve the resistance of the coatings against ultraviolet (UV) degradation and corrosion. It is believed that this process will improve the properties of the polyurethane top coating used in many industries against environmental factors.
Badly approximable affine forms and Schmidt games

For any real number θ, the set of all real numbers x for which there exists a constant c(x)>0 such that infp∈Z|θq−x−p|⩾c(x)|q| for all q∈Z\{0} is a 1/8-winning set.
Simulation of Flowfield Around a Ram-Air Personnel Parachute Canopy

The flowfield around a model MC-4 ram-air personnel parachute canopy was examined using the steady, incompressible Navier–Stokes equations together with the one-equation Spalart–Allmaras turbulence model. A finite volume flow solver was used to compute the flowfield, forces, and moments on the canopy in steady glide and at sideslip. The canopy surfaces were assumed to be impermeable and rigid. The oncoming flow barely penetrates the canopy opening, and creates a large separation bubble below the lower lip of each half-cell. The flow does not reattach, and a thick boundary layer is present on the lower surface of the canopy. The flow over the upper surface of the canopy remains attached until the separation point near the trailing edge. The lift increases linearly with the angle of attack up to about 12 deg, whereas the quarter-chord pitching moment decreases nearly linearly between 2 and 12 deg angle of attack. For sideslip angles up to 20 deg, the side force increases linearly with the sideslip angle eve...
Electoral poaching and party identification

In dieser Studie wird der Wahlkampf in einem Modellrahmen mit umverteilender Politik untersucht. Dabei gehen wir von den Annahmen deterministischen Wahlverhaltens und heterogenen Wahlerbindung an die politischen Parteien aus. Wir generieren eine naturliche Messgrose fur die Starke einer Partei. Sie beruht auf der Grose und Intensitat der parteiloyalen Wahlersegmente und zeigt wie sich das Verhalten der Parteien verandert in Abhangigkeit von der Starke der beiden Parteien. Im Gleichgewicht versuchen die Parteien einen Teil der loyalen Wahlerschaft der Gegenpartei mit dem Versprechen hoher Transferzahlungen abzuwerben, wahrend den restlichen Teilen der gegnerischen Wahlerschaft Null-Transfers in Aussicht gestellt werden. Die Anzahl dieser letzteren Oppositionswahler, die keine Transferzahlungen erhalten werden, und das Niveau der Ungleichverteilung der Nutzen durch die im Gleichgewicht resultierende Umverteilung steigen in Abhangigkeit von der Starke der Oppositionspartei. Des weiteren wird eine Messgrose der politischen Polarisierung konstruiert, das mit der Summe und Symmetrie der Parteienstarke steigt. Als Ergebnis lasst sich feststellen, dass das erwartete ex-post Ungleichgewicht des Nutzens der implementierten Politik ansteigt, je starker die politische Polarisierung ist.
Case study: Use of vibration therapy in the treatment of diabetic peripheral small fiber neuropathy

Abstract The aim of the study was to describe a case of type II diabetic peripheral small fiber neuropathic pain treated with whole body vibration therapy after a failed trial of conventional drugs and interventional pain management. A 64-year-old male had chronic diabetic peripheral neuropathic pain in both his feet for about 2 years. The patient tried multiple pain medications and various interventional pain treatments without significant pain relief. After 4 weeks of whole body vibration treatment the patient’s pain level and gait patterns significantly improved. These findings illustrate the importance of considering whole body vibration as a complimentary treatment in patients with diabetic peripheral neuropathic pain.
A short and general synthesis of 1,3‐dihydro‐6‐heteroaryl‐5‐perfluoroalkyl‐2H‐imidazo[4,5‐b]pyridin‐2‐ones

Trifluoro or pentafluoroacylation of heteroaryl-enamines 2a,b gave the corresponding perfluoroacylated heteroaryl-enamines 3a-c. Heating the latter compounds with diethyl iminomalonate gave 2-amino-3-pyridinecarboxylates 4a-c. Hydrolysis to the free acids 5a-c, and reaction with diphenylphosphoryl azide afforded the desired 1,3-dihydro-6-heteroaryl-5-perfluoroalkyl-2H-imidazo[4,5-b]pyridin-2-ones 6a-c.
The nephrotoxicity of immunosuppressive drugs

Acute and chronic nephrotoxicity frequently limits the therapeutic benefits of immunosuppressive therapy for transplant and autoimmune indications. The clinical aspects, pathophysiology, and relevant pharmacology of current and future immunosuppressive drugs are reviewed in this paper. Insights gained from experimental models of chronic nephrotoxicity associated with tubulointerstitial fibrosis are presented.
Design, Fabrication, and Performance of Open Source Generation I and II Compliant Hydrodynamic Gas Foil Bearings

Foil gas bearings are self-acting hydrodynamic bearings made from sheet metal foils comprised of at least two layers. The innermost “top foil” layer traps a gas pressure film that supports a load while a layer or layers underneath provide an elastic foundation. Foil bearings are used in many lightly loaded, high-speed turbomachines such as compressors used for aircraft pressurization and small microturbines. Foil gas bearings provide a means to eliminate the oil system leading to reduced weight and enhanced temperature capability. The general lack of familiarity of the foil bearing design and manufacturing process has hindered their widespread dissemination. This paper reviews the publicly available literature to demonstrate the design, fabrication, and performance testing of both first- and second-generation bump-style foil bearings. It is anticipated that this paper may serve as an effective starting point for new development activities employing foil bearing technology.
ISOLATION AND EXPULSION OF DIVERGENCES IN QUANTUM FIELD THEORY

Divergences that arise in the quantization of scalar quantum field models by means of a lattice-space functional integration may be attributed to a single integration variable, and this fact is demonstrated by showing that if the integrand for that single integration variable is appropriately changed, then a perturbation expansion becomes order-by-order finite and divergence free. The paper concludes with a brief review of a current proposal of how an auxiliary, nonclassical potential added to the lattice action of a relativistic scalar field quantization may automatically render an analogous change of the integrand, and thus may lead, as well, to nontrivial and divergence-free results.
Deduced sequence of the bovine coronavirus spike protein and identification of the internal proteolytic cleavage site.

Abstract The sequence of the spike (also called peplomer or E2) protein gene of the Mebus strain of bovine coronavirus (BCV) was obtained from cDNA clones of genomic RNA. The gene sequence predicts a 150,825 mol wt apoprotein of 1363 amino acids having an N-terminal hydrophobic signal sequence of 17 amino acids, 19 potential N-linked glycosylation sites, a hydrophobic anchor sequence of approximately 17 amino acids near the C terminus, and a hydrophilic cysteinerich C terminus of 35 amino acids. An internal LysArgArgSerArgArg sequence predicts a protease cleavage site between amino acids 768 and 769 that would separate the S apoprotein into S1 and S2 segments of 85690 and 65153 mol wt, respectively. Amino terminal amino acid sequencing of the virion-derived gp100 spike subunit confirmed the location of the predicted cleavage site, and established that gp120 and gp100 are the glycosylated virion forms of the S1 and S2 subunits, respectively. Sequence comparisons between BCV and the antigenically related mouse hepatitis coronavirus revealed more sequence divergence in the putative knob region of the spike protein (S1) than in the stem region (S2).
Synthetic Studies toward SNF4435 C and SNF4435 D

A synthetic approach toward the immunosuppressants SNF3345 C and SNF4435 D featuring a tandem Stille coupling/electrocyclization cascade is described.
The end of nanochannels

Current theories of nanochannel flow impose no upper bound on flow rates, and predict friction through nanochannels can be vanishingly small. We reassess neglecting channel entry effects in extremely long channels and find violations at the nanoscale. Even in frictionless nanochannels, end effects provide a finite amount of friction. Hence, the speed at which nanochannels transport liquids is limited. Flow-rate and slip-length measurements are reevaluated using calculations which include end-effect friction. End effects are critical for the design of new technological devices and to understand biological transport.
Developing Technologies for Synthetic Fuels

The world is undergoing yet another energy transition, this time from fossil sources to renewable sources. In this transition, synthetic fuels represent a bridge from petroleum to renewables. The paper will first consider the need for and the possible timing of a synthetic fuels industry and the technology necessary to support it. The large variety of synthetic fuels and their potential roles will be addressed. Finally, the outlook for commercialization of these technologies will be discussed.
Low Temperature Simulation of Subliming Boundary-Layer Flow in Jupiter Atmosphere

A low-temperature approximate simulation for the sublimation of a graphite heat shield under Jovian entry conditions is studied. A set of algebraic equations is derived to approximate the governing equation and boundary conditions, based on order-of-magnitude analysis. Characteristic quantities such as the wall temperature and the subliming velocity are predicted. Similarity parameters that are needed to simulate the most dominant phenomena of the Jovian entry flow are also given. An approximate simulation of the sublimation of the graphite heat shield is performed with an air-dry-ice model. The simulation with the air-dry-ice model may be carried out experimentally at a lower temperature of 3000 to 6000 K instead of the entry temperature of 14,000 K. The rate of graphite sublimation predicted by the present algebraic approximation agrees to the order of magnitude with extrapolated data. The limitations of the simulation method and its utility are discussed.
Homology cobordism and classical knot invariants

In this paper, we define and investigate \( \mathbb{Z}_2 \)-homology cobordism invariants of \( \mathbb{Z}_2 \)-homology 3-spheres which turn out to be related to classical invariants of knots. As an application, we show that many lens spaces have infinite order in the \( \mathbb{Z}_2 \)-homology cobordism group and we prove a lower bound for the slice genus of a knot on which integral surgery yields a given \( \mathbb{Z}_2 \)-homology sphere. We also give some new examples of 3-manifolds which cannot be obtained by integral surgery on a knot.
Moduli spaces of d-connections and difference Painlevé equations

We show that difference Painleve equations can be interpreted as isomorphisms of moduli spaces of difference connections (d-connections) on P1 with given singularity structure. In particular, we derive a difference equation that lifts to an isomorphism between A2(1)*-surfaces in Sakai's classification (see [29]); it degenerates to both difference Painleve V and classical (differential) Painleve VI equations. This difference equation has been known before under the name of asymmetric discrete Painleve IV equation
BPS states and minimal surfaces

It was observed recently, that the low-energy effective action of the four-dimensional supersymmetric theories may be obtained as a certain limit of M-theory. From this point of view, the BPS states correspond to the minimal area membranes ending on the M-theory 5-brane. We prove that for the configuration, corresponding to the SU(2) super-Yang-Mills theory, the BPS spectrum is correctly reproduced, and develop techniques for analyzing the BPS spectrum in more general cases. We show that the type of the supermultiplet is related to the topology of the membrane: disks correspond to hypermultiplets, and cylinders to vector multiplets. We explain the relation between minimal surfaces and geodesic lines, which shows that our description of BPS states is closely related to one arising in Type II string compactification on Calabi-Yau threefolds.
System identification via singular value decomposition

The problem of identifying linear time invariant system parameters from their truncated impulse response data is studied. The authors analyse the algorithm originally proposed by Kung, and later modified by others, which is based on the singular value decomposition of the Hankel matrix. They propose a modified algorithm which generates more accurate results.
On Four-Dimensional Anti-self-dual Gradient Ricci Solitons

In this note we prove that any four-dimensional half-conformally flat gradient steady Ricci soliton must be either isometric to the Bryant’s soliton (up to a scaling), or with zero Ricci curvature. We also classify four-dimensional half-conformally flat gradient shrinking Ricci solitons.
The East-West Asymmetry of the Cosmic Radiation in High Latitudes and the Excess of Positive Mesotrons

The slight east-west asymmetry of the cosmic radiation in high latitudes, now confirmed by Seidl, is interpreted to be the result of the deflection by the earth's magnetic field of the mesotron component while the rays are losing energy by ionization in the atmosphere. Since this component contains about twenty percent more positive than negative rays these deflections result in an asymmetry. Orbits of rays, including those in the range of energy where rest mass cannot be neglected, have been investigated and the deflections determined. It is assumed that deflections without energy loss, namely, those of the primary rays described by the theory of Lema\^{\i}tre and Vallarta, result in a symmetrical distribution for the energy ranges concerned. The asymmetry is traced to the difference between the actual deflection and that of a ray which loses no energy. The "difference" deflection $\ensuremath{\delta}$ shifts the angular distribution so that rays which, in the absence of a field, would have produced an intensity proportional to ${cos}^{2}\ensuremath{\zeta}$ at zenith angle $\ensuremath{\zeta}$ actually produce this intensity at an angle $\ensuremath{\zeta}+\ensuremath{\delta}$. Asymmetries calculated in this way agree with the observed values, and give the correct variation of asymmetry with zenith angle and elevation. Although the data are meager, the theory seems to be in accord with the existing evidence regarding the effect of absorbing material upon the asymmetry.
Temporal segmentation of video using frame and histogram space

Two algorithms are presented for the detection of gradual transitions in video sequences. The first is a dissolve detection algorithm utilizing certain properties of a dissolve's trajectory in image-space. It is implemented both as a simple threshold-based detector, and as a parametric detector by modeling the error properties of the extracted statistics. The second is an algorithm to detect a wide variety of wipes based on image histogram characteristics during such transitions. Both algorithms operate in the compressed domain, requiring only partial decoding of the compressed video stream. Experiments show the algorithms perform as well as-and in some cases, better than-full-frame methods, on a wide variety of gradual transitions, and can operate significantly faster than real-time.
Duality and universality for the Chern-Simons bosons.

By mapping the relativistic version of the Chern-Simons-Landau-Ginzburg theory in 2+1 dimensions to the three-dimensional (3D) lattice Villain x-y model coupled with the Chern-Simons gauge field, we investigate phase transitions of Chern-Simons bosons in the limit of strong coupling. We construct algebraically exact duality and flux attachment transformations of the lattice theories, corresponding to analogous transformations in the continuum limit. These transformations are used to convert the model with arbitrary fractional Chern-Simons coefficient \ensuremath{\alpha} to a model with \ensuremath{\alpha} either zero or 1. We show that, unless the corrections of cubic and higher power in momenta, irrelevant near corresponding fixed points, render the phase transition first order, the phase transition in the original model is either in the 3D x-y or a ``fermionic'' universality class. \textcopyright{} 1996 The American Physical Society.
On project-based learning through the vertically-integrated projects program

Georgia Tech's Colleges of Engineering and Computing initiated the Vertically-Integrated Projects (VIP) program in January 2009. Undergraduate students that join VIP teams earn academic credit for participating in design efforts that assist faculty and graduate students with research and development issues in their technical areas. The teams are: multidisciplinary — drawing students from around the university; vertically-integrated — maintaining a mix of sophomores through PhD students each semester; and long-term — each undergraduate student may participate in a project for up to six semesters. We describe the Video and Image Annotation VIP (VIA-VIP) project, which provides undergraduates unique opportunities to learn and apply state-of-the-art video-mining algorithms by processing a large archive of football videos recorded from GT football games. Their results are documented. Based on their feedback we believe the VIA-VIP course is on track to meet the needs of undergraduates in areas they don't usually see in the traditional undergraduate classroom.
Externalities and Cities

There is an elegant geometric theory of cities that describes the location of activities and the equilibrium pattern of land prices. In the simplest versions of the theory, production is centered at the city center, and people live at differing distances from their jobs. In choosing a residential location, households face a tradeoff between expensive land near the center with small travel times, and cheap land farther out with large travel costs. Everyone who has looked for housing in any city or suburb knows the reality of this tradeoff. The objective of this paper is to rework the model of a city with a spatial structure imposed on the production externality: The effect of one producer on the productivity of another is assumed to be a decreasing function of the distance between the two. By itself, this postulated force will pull producers together, or pull all of them toward a point I designate the center. The need for land as a factor of production will keep the city from collapsing on this point. The tension between these two factors will generate a land price gradient in equilibrium. (Copyright: Elsevier)
Solution of the Thirring model with imaginary mass and massless scattering

Abstract The Thirring model with imaginary mass (or the sine-Gordon model with imaginary coupling) is deeply related to all the flows between minimal conformal theories. We solve this model explicitly using the Bethe ansatz. We find that there are left and right moving massless excitations with non trivial LR scattering. We compute the S -matrix and recover the result conjectured by Fendley et al.
Recent developments of direct rhenium-catalyzed [1,3]-transpositions of allylic alcohols and their silyl ethers

The direct metal-catalyzed [1,3]-transposition of allylic alcohols and allylic silyl ethers is a synthetically useful isomerization process that occurs via [3,3]-sigmatropic rearrangement induced by high oxidation state oxometal complexes. The isomerization requires only a catalytic amount of promoter, and high chirality transfer can be achieved. Thus, it bears a significant potential to become a powerful tool in multistep synthesis. Although [1,3]-transposition of allylic alcohols has been known since the late 1960s, the development of synthetically useful protocols that allow for a high level of regio- and stereoselectivity control and their synthetic applications have emerged only recently. This tutorial review summarizes recently developed regioselective [1,3]-transpositions of allylic alcohols and silyl ethers and their applications to natural product synthesis.
Impacts of Weather and Time Horizon Selection on Crop Insurance Ratemaking: A Conditional Distribution Approach

An important issue in the agricultural risk and actuarial literatures is the extent to which sample period selection affects the accuracy of insurance rating. This is typically more problematic in agriculture than in other types of insurance because of the variation in weather through time. A conditional Weibull distribution approach is developed that explicitly models the interaction of weather, technology, and other variables on probabilistic yield outcomes to address this issue. Results from an application with an extensive producer-level yield dataset representing commercial-scale Illinois firms suggest that the impact of weather heterogeneity on risk estimation across reasonable samples is likely not as great as is often claimed. The results also suggest that yield risk is decreasing significantly through time and indicate the presence of trend acceleration. A rating analysis indicates that violations in the risk evolution assumptions of the rating approaches used in the Federal Crop Insurance Progra...
Reflections on the design of a CAI operating system

A time shared general purpose computer programmed to operate in conversational mode may be used as a vehicle for computer aided instruction (CAI). Although at present CAI is a relatively expensive medium the outlook is that as the efficiency of time sharing system increases, the cost per terminal of such a CAI system will decrease and CAI will become practical for more and more educational applications. As a result R&D activity in CAI has increased markedly in the last few years.
Efficient fiber-optical interface for nanophotonic devices

We demonstrate a method for efficient coupling of guided light from a single-mode optical fiber to nanophotonic devices. Our approach makes use of single-sided conical tapered optical fibers that are evanescently coupled over the last ∼10 μm to a nanophotonic waveguide. By means of adiabatic mode transfer using a properly chosen taper, single-mode fiber-waveguide coupling efficiencies as high as 97(1)% are achieved. Efficient coupling is obtained for a wide range of device geometries, which are either singly clamped on a chip or attached to the fiber, demonstrating a promising approach for integrated nanophotonic circuits, and quantum optical and nanoscale sensing applications.
Identifying the Drivers of Social Entrepreneurial Impact: Theoretical Development and an Exploratory Empirical Test of SCALERS

Abstract The scaling of social entrepreneurial impact is an important issue in the field of social entrepreneurship. While researchers have focused relatively little theoretical and empirical attention on scaling, a recently proposed set of drivers of scaling – incorporated into what has been labeled the SCALERS model – may provide guidance for new theoretical and empirical work on scaling of social impact. In this study, prior work on the drivers of scaling is extended by adding to the theoretical foundations upon which the SCALERS model is developed and by providing an initial empirical test of the SCALERS model. Initial empirical support is found for the SCALERS model of scaling social entrepreneurial impact.
Polyhedral models for generalized associahedra via Coxeter elements

Motivated by the theory of cluster algebras, F. Chapoton, S. Fomin, and A. Zelevinsky associated to each finite type root system a simple convex polytope, called generalized associahedron. They provided an explicit realization of this polytope associated with a bipartite orientation of the corresponding Dynkin diagram. In the first part of this paper, using the parametrization of cluster variables by their g-vectors explicitly computed by S.-W. Yang and A. Zelevinsky, we generalize the original construction to any orientation. In the second part we show that our construction agrees with the one given by C. Hohlweg, C. Lange, and H. Thomas in the setup of Cambrian fans developed by N. Reading and D. Speyer.