cssi/SciSciGPT-SciSciNet huggingface dataset:
The area of cyclic polygons: Recent progress on Robbins' conjectures

In his works [Discrete Comput. Geom. 12 (1994) 223-236; Amer. Math. Monthly 102 (1995) 523-530] David Robbins proposed several interrelated conjectures on the area of the polygons inscribed in a circle as an algebraic function of its sides. Most recently, these conjectures have been established in the course of several independent investigations. In this note we give an informal outline of these developments.
Direct synthesis of β-mannosides. Synthesis of β-D-xyl-(1→2)-β-D-man-(1→4)-α-D-Glc-OMe: A trisaccharide component of the Hyriopsis schlegelii glycosphingolipid. Formation of an orthoester from a xylopyranosyl sulfoxide

Abstract A concise synthesis of the title trisaccharide is described in which the key β-mannosylation reaction is achieved directly, with high yield and selectivity, by triflic anhydride mediated coupling of S -ethyl2- O -allyl-3- O -benzyl-4,6- O -benzylidene-1-deoxy-1-thia-α-D-mannopyranoside S -( R )-oxide with methyl 2,3,6-tri- O -benzyl-α-D-glucopyranoside. After deallylation of the so-formed disaccharide, β-xylopyranosylation is brought about by reaction with α -tri- O -benzoyl xylopyranosyl bromide activated with silver triflate. Attempted xylosylation of cyclohexanol with S -phenyl2,3,4-tri- O -benzoyl-1-deoxy-1-thio-β-D-xylopyranoside S -oxide, activated by triflic anhydride, and with the corresponding thioglycoside in the presence of benzenesulfenyl triflate both led to the formation of an orthoester rather than the anticipated β-xyloside. Treatment of this orthoester with tin tetrachloride promoted its rearrangement to the β-xyloside. The conformation and configurational assignment of tri- O -benzoyl-β-xylopyranosides is discussed.
Adaptive Controller Design and Disturbance Attenuation for Sequentially Interconnected SISO Linear Systems Under Noisy Output Measurements

This note presents a robust adaptive controller design for a special class of linear system, consisting of two sequentially interconnected SISO linear subsystems, S1 and S2, under noisy output measurements and with additional feedback. We formulate the robust adaptive control problem as a nonlinear H∞-optimal control problem under imperfect state measurements, and then solve it using game theory. A cost-to-come function formulation is utilized in the analysis in order to derive identifiers for S1 and S2, and integrator backstepping methodology is applied recursively to obtain the control law, which guarantees the boundedness of closed-loop signals, and achieves asymptotic tracking, under some assumptions. The closed-loop system exhibits a guaranteed disturbance attenuation level with respect to the exogenous disturbance inputs, where the ultimate attenuation lower bound for the achievable performance level is equal to the noise intensity in the measurement channel of S1.
An iterative noncoherent relay receiver for the two-way relay channel

Digital network coding improves the throughput of the two-way relay channel by allowing multiple sources to transmit simultaneously to the relay. This work considers the development of a relay receiver applying a specific modulation and channel coding technique - turbo-coded noncoherent orthogonal FSK in the two-way relay channel operated with digital network coding. The relay receiver supports any modulation order which is a power of two, and iterative channel decoding with information feedback from decoder to demodulator, using bit interleaved coded modulation with iterative decoding (BICM-ID). The performance of the receiver is investigated in fading channels through error-rate simulations and capacity analysis, and results show an energy efficiency improvement of 0.5-0.9 dB over similar systems which do not utilize BICM-ID.
Kakeya sets and directional maximal operators in the plane

We completely characterize the boundedness of planar directional maximal operators on Lp. More precisely, if Ω is a set of directions, we show that MΩ, the maximal operator associated to line segments in the directions Ω, is unbounded on Lp for all p 1
AN EXPLORATION OF MEASURES FOR COMPARING MEASUREMENTS WITH THE RESULTS FROM METEOROLOGICAL MODELS FOR MEXICO CITY

Los Alamos National Laboratory and Instituto Mexicano del Petroleo have completed a joint study of options for improving air quality in Mexico City. We used a three-dimensional, prognostic, higher-order turbulence model for atmospheric circulation (HOTMAC) to treat domains that include an urbanized area. We tested the model against routine measurements and those of a major field program. During the field program, measurements included: (1) lidar measurements of aerosol transport and dispersion, (2) aircraft measurements of winds, turbulence, and chemical species aloft, (3) aircraft measurements of skin temperatures, and (4) Tethersonde measurements of winds and ozone. We made both graphical and statistical comparisons and we have reported some of the comparisons to provide insight into the meaning of statistical parameters including the index of agreement.
Effects of metal enrichment and metal cooling in galaxy growth and cosmic star formation history

We present the results of a numerical study on the effects of metal enrichment and metal cooling on galaxy formation and cosmic star formation (SF) history using cosmological hydrodynamic simulations. We find the following differences in the simulation with metal cooling when compared to the run without it: (i) the cosmic star formation rate is enhanced by about 50 and 20 per cent at z = 1 and 3, respectively; (ii) the gas mass fraction in galaxies is lower; (iii) the total baryonic mass function (gas + star) at z = 3 does not differ significantly, but shows an increase in the number of relatively massive galaxies at z = 1 and (4) the baryonic mass fraction of intergalactic medium (IGM) is reduced at z < 3 due to more efficient cooling and gas accretion on to galaxies. Our results suggest that the metal cooling enhances the galaxy growth by two different mechanisms: (i) increase in SF efficiency in the local interstellar medium and (ii) increase in IGM accretion on to galaxies. The former process is effective throughout most of the cosmic history, while the latter is effective only at z < 3 when the IGM is sufficiently enriched by metals owing to feedback.
The world-wide telescope

Mining vast databases of astronomical data, this new online way to see the global structure of the universe promises to be not only a wonderful virtual telescope but an archetype for the evolution of computational science.
Chemoselective Protection of α-Ketoacids by Direct Annulations with Oximes

Oximes and α-ketoacids undergo an unexpectedly facile and chemoselective annulation to afford 2,5-dihydrooxazole 3-oxides. The resulting cyclic nitrones serve as chemically and configurationally stable masked α-ketoacids that can be easily elaborated and manipulated. Deprotection is achieved by mild reduction with zinc metal and hydrolysis. This methodology allows for the protection, elaboration, and deprotection of enantiopure peptide derived α-ketoacids, which are the key starting materials for the chemoselective ketoacid-hydroxylamine peptide ligation.
The Political Economy of Village Sanitation in South India: Capture or Poor Information?

Despite efforts to mandate and finance local governments' provision of environmental sanitation services, outcomes remain poor in the villages surveyed in the four South Indian states. The analysis indicates some key issues that appear to hinder improvements in sanitation. Local politicians tend to capture sanitary infrastructure and cleaning services for themselves, while also keeping major village roads reasonably well-served. Their decisions suggest, however, that they neither understand the health benefits of sanitation, nor the negative externalities to their own health if surrounding areas are poorly served. Our findings suggest that improving sanitary outcomes requires disseminating information on the public goods nature of their health benefits, as well as on the local government's responsibilities. It also requires putting public health regulations in place, along with measures to enable accountability in service provision.
Rational connectivity and sections of families over curves

Abstract A “pseudosection” of the total space X of a family of varieties over a base variety B is a subvariety of X whose general fiber over B is rationally connected. We prove a theorem which is a converse, in some sense, of the main result of [T. Graber, J. Harris, J. Starr, Families of rationally connected varieties, J. Amer. Math. Soc. 16 (2003) 69–90]: a family of varieties over B has a “pseudosection” if its restriction to each one-parameter subfamily has a “pseudosection” (which, due to [T. Graber, J. Harris, J. Starr, Families of rationally connected varieties, J. Amer. Math. Soc. 16 (2003) 69–90], holds if and only if each one-parameter subfamily has a section). This is used to give a negative answer to a question posed by Serre to Grothendieck: There exists a family of O -acyclic varieties (a family of Enriques surfaces) parametrized by P 1 with no section.
Extreme value theory for processes with periodic variances

Suppose {Xn n ≥ 1} is a stationary sequence satisfying the D and D1 mixing conditions given by Adler [1]. Suppose further that g and h are functions on the positive integers such that h is positive, periodic with integer period p ≥ 1 and g satisfies a certain growth rate condition. By first exhibiting the weak convergence of a sequence of point processes related to , we derive the asymptotic distribution of . When {Xn} is in the maximal domain of attraction of A(x) = exp(-e -xx), {Mn} is attracted to (A(x))q/p where . If {Xn} is in the maximal domain of attraction of G(x) = exp(-x -α) then {Mn} is attracted to (G(x)) θ where . These asymptotic results lead to a new method for estimating the level of the k-year return period, a quantity of interest in many climatological studies. An analysis of the daily rainfall totals in Homestead, Florida from 1939-1979 is provided, illustrating this estimation procedure.
Synthesis of the octahydro-8b-azaacenaphthylene ring system, a portion of the dimeric coccinellid alkaloids

Abstract The “dimeric” coccinellid alkaloids exochomine ( 1 ), chilocorine A ( 2 ), and chilocorine B ( 3 ) represent a challenging set of synthetic targets. An interesting structural feature of these alkaloids is the novel 3,4-disubstituted octahydro-8b-azaacenaphthylene ring system. Representatives of this ring system have been synthesized and functionalized for possible use in a synthetic approach to these alkaloids.
IS THE UNIVERSE MORE TRANSPARENT TO GAMMA RAYS THAN PREVIOUSLY THOUGHT

The MAGIC collaboration has recently reported the detection of the strong gamma-ray blazar 3C279 during a 1-2 day flare. They have used their spectral observations to draw conclusions regarding upper limits on the opacity of the Universe to high energy gamma-rays and, by implication, upper limits on the extragalactic mid-infrared background radiation. In this paper we examine the effect of gamma-ray absorption by the extragalactic infrared radiation on intrinsic spectra for this blazar and compare our results with the observational data on 3C279. We find agreement with our previous results, contrary to the recent assertion of the MAGIC group that the Universe is more transparent to gamma-rays than our calculations indicate. Our analysis indicates that in the energy range between approx. 80 and approx. 500 GeV, 3C279 has a best-fit intrinsic spectrum with a spectral index approx. 1.78 using our fast evolution model and approx. 2.19 using our baseline model. However, we also find that spectral indices in the range of 1.0 to 3.0 are almost as equally acceptable as the best fit spectral indices. Assuming the same intrinsic spectral index for this flare as for the 1991 flare from 3C279 observed by EGRET, viz., 2.02, which lies between our best fit indeces, we estimate that the MAGIC flare was approx.3 times brighter than the EGRET flare observed 15 years earlier.
Synchrotron-Loss Spectral Breaks in Pulsar-Wind Nebulae and Extragalactic Jets

Flows of synchrotron-emitting material can be found in several astrophysical contexts, including extragalactic jets and pulsar-wind nebulae (PWNe). For X-ray synchrotron emission, flow times are often longer than electron radiative lifetimes, so the effective source size at a given X-ray energy is the distance electrons radiating at that energy can convect before they burn off. Since synchrotron losses vary strongly with electron energy, the source size drops with increasing X-ray energy, resulting in a steepening of the synchrotron spectrum. For homogeneous sources, this burnoff produces the well known result of a steepening by 0.5 in the source's integrated spectral index. However, for inhomogeneous sources, different amounts of steepening are possible. I exhibit a simple phenomenological picture of an outflow of relativistic electrons with bulk nonrelativistic flow speed, with transverse flow-tube radius, magnetic field strength, matter density, and flow velocity all varying as different powers of distance from the injection point. For such a picture, I calculate the value of the spectral index above the break as a function of the power-law indices, and show the possible range of steepenings. I show that these simple calculations are confirmed by full integrations of source luminosity, which also include the spectral bump below the break from the accumulation of electrons formerly at higher energies. In many cases, extragalactic jets show X-ray synchrotron emission steeper by more than 0.5 than the radio emission; the same phenomenon is exhibited by many PWNe. It is possible that source inhomogeneities are responsible in at least some cases, so that the amount of spectral steepening becomes a diagnostic for source dynamical or geometrical properties.
Why a particle physicist is interested in DNA branch migration

Abstract We describe an explicitly discrete model of the process of DNA branch migration. The model matches the existing data well, but we find that branch migration along long strands of DNA ( N ≳ 40 bp) is also well modeled by continuum diffusion. The discrete model is still useful for guiding future experiments.
Selective methoxy ether cleavage of 2,6-dimethoxyphenol followed by a selective acylation

Abstract A Friedel–Crafts reaction of 2,6-dimethoxyphenol in the presence of aluminum chloride and propanoyl or butanoyl chloride, respectively, lead, at elevated temperatures, to a selective cleavage of one of the methoxy groups followed by a selective acylation of the meta position with respect to the phenolic hydroxyl group. Under the same reaction conditions 2-methoxyphenol does not get demethylated; a mechanism to account for these findings is proposed. This reaction gives access to a variety of ortho -acylated catechols. Substituted catechols are widely used in supramolecular chemistry and are precursors of pesticides, flavors, and fragrances. Additionally, catechol moieties are found in various natural products.
Enhanced stimulated Raman scattering in slow-light photonic crystal waveguides

We investigate slow-light enhancement of stimulated Raman scattering in monolithic silicon photonic crystal defect waveguides. The applied Bloch-Floquet formalism demonstrates remarkable gain enhancements up to 104 at the band-edges, while considering disorder, absorption and coupling.
A new kinetic model for interdiffusion at semicrystalline polymer interfaces

A kinetic model has been developed to describe the behavior of semicrystalline polymer interfaces. In these systems, the competition between interdiffusion and crystallization drives the overall transport. The crystallization rate is based on the Avrami equation, in which the Avrami exponent and the crystallization rate constant as a function of temperature and blend composition are determined by in situ optical microscopy and differential scanning calorimetry. The mutual diffusion coefficient is obtained by using the fast mode theory. The predicted density profiles as a function of position are used to extract the interfacial widths, which are affected by molecular weight, equilibrium degree of crystallinity, and temperature. At low temperatures, the crystallization rate is fast, and the crystals present near the interface hinder the interdiffusion, causing the interfacial width to be small. At high temperatures, the crystallization is much slower, and interdiffusion dominates crystallization. The model predictions are compared with interfacial behavior observed by transmission electron microscopy and small angle X-ray scattering in a system composed of polyethylene and isotactic polypropylene and the agreement with the experiments is satisfactory.
Extracting galactic binary signals from the first round of Mock LISA Data Challenges

We report on the performance of an end-to-end Bayesian analysis pipeline for detecting and characterizing galactic binary signals in simulated LISA data. Our principal analysis tool is the blocked-annealed Metropolis–Hasting (BAM) algorithm, which has been optimized to search for tens of thousands of overlapping signals across the LISA band. The BAM algorithm employs Bayesian model selection to determine the number of resolvable sources, and provides posterior density functions for all the model parameters. The BAM algorithm performed almost flawlessly on all the round 1 Mock LISA Data Challenge data sets, including those with many highly overlapping sources. Some misses were later traced to a particular flaw in the coding that affected high frequency sources. In addition to the BAM algorithm we also successfully tested a genetic algorithm (GA), but only on data sets with isolated signals as the GA has yet to be optimized to handle large numbers of overlapping signals.
Stringy corrections to Kähler potentials, SUSY breaking, and the cosmological constant problem

The moduli of N = 1 compactifications of IIB string theory can be stabilized by a combination of fluxes (which freeze complex structure moduli and the dilaton) and nonperturbative superpotentials (which freeze Kahler moduli), typically leading to supersymmetric AdS vacua. We show that stringy corrections to the Kahler potential qualitatively alter the structure of the effective scalar potential even at large volume, and can give rise to non-supersymmetric vacua including metastable de Sitter spacetimes. Our results suggest an approach to solving the cosmological constant problem, so that the scale of the 1-loop corrected cosmological constant can be much smaller than the scale of supersymmetry breaking.
The Pressurized dE/dx System in the CLEO Detector at CESR

A unique part of the CLEO Detector at CESR is the pressurized wire proportional chamber system for particle identification using measurements of ionization loss (dE/dx) in gaseous argon. Each particle traverses the ~ 80 cm thick detector and leaves 117 ionization samples. Data obtained from e+e- collisions at CESR in the 10 GeV center of mass energy region have been analyzed. Initial results showing the most probable ionization loss of hadrons and leptons as a function of their momenta will be presented. Also we describe the geometrical, mechanical and electrical construction of this device.
Wealth-varying intertemporal elasticities of substitution: Evidence from panel and aggregate data☆

Abstract This paper constructs and estimates a model of consumer preferences in which the intertemporal elasticity of substitution (IES) of consumption expenditure rises with the level of wealth. The purpose of this paper is to measure the effect that systematic variation in the IES of poor and rich consumers has on the IES of aggregate consumption expenditure. We find economically significant differences in the IES of poor and rich consumers in Indian panel data on the consumption of individual households. We also find economically significant differences in the IES measured in aggregate time series data for the U.S. and India.
On the Binary Nature of Dust-encircled BD +20 307

Three epochs of high-resolution spectra of the star BD +20 307 show that it is a short-period (~3.4 day) spectroscopic binary of two nearly identical stars. Surprisingly, the two stars, although differing in effective temperature by only ~250 K and having a mass ratio of 0.91, show very different Li line equivalent widths. A Li 6707 A line is detected from only the primary star, and it is weak. This star is therefore likely to be older than 1 Gyr. If so, the large amount of hot circumbinary dust must be from a very large and recent, but very late evolutionarily, collision of planetesimals.
Stanley depth of complete intersection monomial ideals and upper-discrete partitions

Abstract Let I be an m-generated complete intersection monomial ideal in S = K [ x 1 , … , x n ] . We show that the Stanley depth of I is n − ⌊ m 2 ⌋ . We also study the upper-discrete structure for monomial ideals and prove that if I is a squarefree monomial ideal minimally generated by 3 elements, then the Stanley depth of I is n − 1 .
The rise, fall and reinvention of combinatorial chemistry

Combinatorial chemistry provides a powerful tool for the rapid creation of large numbers of synthetic compounds. Ideally, these libraries should be a rich source of bioactive molecules, but there is the general feeling that the initial promise of combinatorial chemistry has not yet been realized. In particular, enthusiasm for conducting unbiased (non-structure-guided) screens of large libraries for protein or RNA ligands has waned. A central challenge in this area is to devise methods for the synthesis of chemically diverse, high-quality libraries of molecules with many of the desirable features of natural products. These include diverse functionality, a significant representation of chiral sp3 centers that provide conformational bias to the molecule, significant skeletal diversity, and good pharmacokinetic properties. However, these libraries must be easy to make from cheap, readily available building blocks, ideally those that would support convenient hit optimization/structure reactivity relationship studies. Meeting these challenges will not be easy. Here I review some recent advances in this area and provide some thoughts on likely important developments in the next few years.
Chiral reagents for the determination of enantiomeric excess and absolute configuration using NMR spectroscopy.

Recent advances in the development of chiral derivatizing and solvating agents that facilitate the determination of enantiomeric excess and absolute configuration are reviewed. These include metal-containing species, host-guest systems, donor-acceptor compounds, and liquid crystal discriminating agents. In the aggregate, these reagents can be used to analyze a wide range of compound classes.
Interaction of Compressor Rotor Blade Wake With Wall Boundary Layer/Vortex in the End-Wall Region

This paper reports the experimental study of the three-dimensional characteristics of the mean velocity of the rotor wake inside the annulus- and hub-wall boundary layers. The measurements were taken with a rotating three-sensor hot wire behind the rotor. This set of measurements probably represents the first set of comprehensive measurements taken inside the annulus- and hub-wall boundary layers. The wake was surveyed at several radial locations inside the boundary layer region and at several axial locations. Interaction of the wake with the annulus-wall boundary layer, secondary flow, tip-leakage flow, and the trailing vortex system results in slower decay and larger width of the wake. The presence of a strong vortex and its merger with the wake is also observed. The end-wall boundary layers and the secondary flow were found to have a substantial effect on both the decay characteristics and the profile of the wake. These and other measurements are reported and interpreted in this paper.
ACM copyrights and plagiarism

As authors consider forums for publication, some common questions involve copyright: Who owns the copyright? May I post a copy of my piece on the Web? Could I publish the material in another publication?
Energy momentum conservation effects on two-particle correlation functions

Two particle correlations are used to extract information about the characteristic size of the system in proton-proton and heavy ion collisions. The size of the system can be extracted from the Bose-Einstein quantum mechanical effect for identical particles. However there are also long range correlations that shift the baseline of the correlation function from the expected flat behavior. A possible source of these correlations is the conservation of energy and momentum, especially for small systems, where the energy available for particle production is limited. A new technique, first used by the STAR collaboration, of quantifying these long range correlations using energy-momentum conservation considerations is presented in this talk. Using Monte Carlo simulations of proton-proton collisions at 900 GeV, it is shown that the baseline of the two particle correlation function can be described using this technique.
Smooth Projective Hashing and Two-Message Oblivious Transfer

We present a general framework for constructing two-message oblivious transfer protocols using a modification of Cramer and Shoup’s notion of smooth projective hashing (Advances in Cryptology—EUROCRYPT’02, Lecture Notes in Computer Science, vol. 2332, pp. 45–64, Springer, Berlin, 2002). This framework is an abstraction of the two-message oblivious transfer protocols of Naor and Pinkas (SODA’01, pp. 448–457, ACM, New York, 2001) and Aiello et al. (Advances in Cryptology—EUROCRYPT’01, Lecture Notes in Computer Science, vol. 2045, pp. 119–135, Springer, Berlin, 2001), whose security is based on the Decisional Diffie–Hellman Assumption. In particular, we give two new oblivious transfer protocols. The security of one is based on the Quadratic Residuosity Assumption, and the security of the other is based on the Nth Residuosity Assumption. Compared to other applications of smooth projective hashing, in our context we must deal also with maliciously chosen parameters, which raises new technical difficulties. We also improve on prior constructions of factoring-based smooth universal hashing, in that our constructions do not require that the underlying RSA modulus is a product of safe primes. (This holds for the schemes based on the Quadratic Residuosity Assumption as well as the ones based on the Nth Residuosity Assumption.) In fact, we observe that the safe-prime requirement is unnecessary for many prior constructions. In particular, the factoring-based CCA secure encryption schemes due to Cramer–Shoup, Gennaro–Lindell, and Camenisch–Shoup remain secure even if the underlying RSA modulus is not a product of safe primes.
Carbocyclization of E,E-1,4-Diphenyl-1,3-butadiene with Dichloroalkanes Mediated by Rieke Metals

Abstract The Rieke metal complexes of barium and strontium readily react with E,E-1,4-diphenyl-1,3-butadiene to form metal-diene reagents. Upon treatment with l .n-dichloroalkanes, these metallocycles are transformed into ring derivatives in excellent chemical yield.
Radiative bulk viscosity

Viscous resistance to changes in the volume of a gas arises when different degrees of freedom have different relaxation times. Collisions tend to oppose the resulting departures from equilibrium and, in so doing, generate entropy. Even for a classical gas of hard spheres, when the mean free paths or mean flight times of constituent particles are long we find a non-vanishing bulk viscosity. Here we apply a method recently used to uncover this result for a classical rarefied gas to radiative transfer theory, and derive an expression for the radiative stress tensor for a grey medium with absorption and Thomson scattering. We determine the transport coefficients through the calculation of the comoving entropy generation. When scattering dominates absorption, the bulk viscosity may be much larger than either the shear viscosity or the thermal conductivity.
Genetic programming: parametric analysis of structure altering mutation techniques

We hypothesize that the relationship between parameter settings, specifically parameters controlling mutation, and performance is non-linear in genetic programs. Genetic programming environments have few means for a priori determination of appropriate parameters values. The hypothesized nonlinear behavior of genetic programming creates difficulty in selecting parameter values for many problems. In this paper we study three structure altering mutation techniques using parametric analysis on a problem with scalable complexity. We find through parameter analysis that two of the three mutation types tested exhibit nonlinear behavior. Higher mutation rates cause a larger degree of nonlinear behavior as measured by fitness and computational effort. Characterization of the mutation techniques using parametric analysis confirms the nonlinear behavior. In addition, we propose an extension to the existing parameter setting taxonomy to include commonly used structure altering mutation attributes. Finally we show that the proportion of mutations applied to internal nodes, instead of leaf nodes, has a significant effect on performance.
Interacting drift-diffusion theory for photoexcited electron-hole gratings in semiconductor quantum wells.

Phase-resolved transient grating spectroscopy in semiconductor quantum wells has been shown to be a powerful technique for measuring the electron-hole drag resistivity ${\ensuremath{\rho}}_{eh}$, which depends on the Coulomb interaction between the carriers. In this Letter we develop the interacting drift-diffusion theory, from which ${\ensuremath{\rho}}_{eh}$ can be determined, given the measured mobility of an electron-hole grating. From this theory we predict a crossover from a high-excitation-density regime, in which the mobility has the ``normal'' positive value, to a low-density regime, in which Coulomb drag dominates and the mobility becomes negative. At the crossover point, the mobility of the grating vanishes.
International trade and macroeconomic dynamics: The case of U.S. bilateral trade with G-7 countries

Abstract The short- and long-run effects of exchange rates, income, interest rates and government spending on U.S. bilateral trade with the other G-7 countries are investigated using an autoregressive distributed lag (ARDL) model. The primary contribution of this study is to consider separating the analysis of exports and imports in an integrated model that empirically encompasses four major schools of thoughts – elasticity, Keynesian income, absorption and monetary approaches – in order to identify macroeconomic linkages to U.S. bilateral trade with the other G-7 countries accurately. Results suggest that, in both the short- and long-run, U.S. imports and exports are highly sensitive to changes in U.S. and foreign income, while U.S. imports and exports are relatively insensitive to changes in bilateral exchange rate. It is also found that both exports and imports are more responsive to changes in government spending than changes in interest rates in both the short- and long-run.
Transition/Adaptation in the Delivery Room and Less RDS: “Don't Just Do Something, Stand There!”

I t is old news that neonatology has changed strikingly with the increased survival of smaller and smaller infants. However, to appreciate the results obtained using continuous positive airway pressure (CPAP) reported by Ammari et al in this issue of The Journal, let’s step back to the 1980s-prior to the frequent use of antenatal corticosteroids or surfactant therapy and to multiple changes in obstetric management of the delivery of low birth weight infants. Most infants b28 weeks gestation were ventilated, had multiple complications, and had a high mortality rate. Avery et al reported in 1987 that the use of CPAP in New York at Columbia University seemed to be associated with less bronchopulmonary dysplasia than did the ventilator management practiced by other neonatal units, an observation that was reinforced by similar comparisons by Van Marter et al in 1992. The weakness of the current report by Ammari et al1 is that it is simply their clinical experience with the use of CPAP to stabilize infants after delivery at Columbia from 1999 to 2002. We remain without randomized controlled trials designed to test the perceived benefits of CPAP, a gap that hopefully will be filled by ongoing trials. However, what I find remarkable about the report is the high percentage of infants with birth weights b1000 g who can breathe in the delivery room and who do not have severe respiratory distress syndrome (RDS). These 2 outcomes are contrary to the clinical experiences of many neonatologists and may be important to understanding the incidence of bronchopulmonary dysplasia.
Melting at alkyl side chain comb polymer interfaces.

Infrared visible sum frequency generation (SFG) spectroscopy has been used to study structure and melting transition temperatures of alkyl-side chain-acrylate comb polymers at air and solid interfaces. At the air interface, the SFG spectra show methyl bands and two transitions are observed: the first, near the bulk melting temperature, ${T}_{m}$, and the second 10--20 \ifmmode^\circ\else\textdegree\fi{}C higher than ${T}_{m}$. The shorter the alkyl side chain, the larger the difference between the two transition temperatures. In contrast, methylene bands are observed at sapphire interface with a single transition near ${T}_{m}$ (C18).
No more business as usual: enticing companies to sharply lower the public health costs of the products they sell

Cigarettes, alcohol, junk food and motor vehicles cause a staggeringly high level of death, injury and disease. Business leaders from the industries that make these products currently try to frame these negative outcomes as 'collateral damage' that is someone else's problem. That framing is not only morally objectionable, but also overlooks the possibility that, with proper prodding, industry could substantially mitigate these public health disasters. A promising regulatory tool called 'performance-based regulation' is a new approach to combating the problem. Simply put, performance-based regulation would impose a legal obligation on manufacturers to reduce their negative social costs. Rather than suing the firms for damages, or telling them how they should run their businesses differently (as typical 'command and control' regimes do), performance-based regulation allows the firms to determine how best to decrease today's negative public health consequences. Like other public health strategies, performance-based regulation shifts the focus away from individual consumers on to those who are far more likely to achieve real public health gains. Analogous to a tax on causing harm that exceeds a threshold level, performance-based regulation seeks to harness private initiative in pursuit of the public good.
Low-latitude coronal holes during solar maximum

Abstract The Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO has been used to observe large low-latitude coronal holes during solar maximum that produced fast solar wind streams. UVCS observations show that large low-latitude coronal holes at solar maximum, coronal holes of at least 10° in longitude, have plasma properties that seem to bridge the gap between solar minimum polar coronal holes and streamers. The ion kinetic perpendicular temperatures in equatorial coronal holes are about 2 times larger than those in a solar minimum equatorial streamer, and about a factor of 2 smaller than those in polar coronal holes above 2 R⊙. The outflow speeds for the large equatorial coronal holes observed by UVCS are 3–4 times lower than those in polar coronal holes between 2 and 3 R⊙. The values for high- and mid-latitude coronal holes are in between those. In all these cases, the in situ data corresponding to these coronal holes showed high-speed wind streams with asymptotic speeds of 600–750 km s−1. These wind speeds approach those observed over polar coronal holes at solar minimum, but the outflow speeds in these coronal holes between 2 and 3 R⊙ are different. In contrast to the polar coronal holes, the bulk of the solar wind acceleration must occur above 3 R⊙ for large low-latitude coronal holes at solar maximum. These observations provide detailed empirical constraints for theoretical models and may be key to understanding how the various types of solar wind plasma are heated and accelerated.
Mid- to high-valent imido and nitrido complexes of iron

This short review summarizes recent advances in the synthesis and reactivity of iron imides and nitrides. Both monometallic and multimetallic assemblies featuring these moieties are discussed. Recent synthetic approaches have led to the availability of new mid- to high-valent iron imides and nitrides, allowing us to begin assembling models to describe the factors influencing their relative stabilities and reactivity patterns.
Bladder injuries following inguinal canal surgery in infants

Surgery of the inguinal canal is very common in infancy. Occasionally, injury of the bladder may occur with severe consequences. The aim of this paper was to warn young surgeons of this serious complication. During the last 2 years, we observed four cases of bladder injury following surgery on inguinal canal. All were males. The indication for surgery was inguinal hernia in three patients and cryptorchidism in one patient. Two cases presented with urinary peritonitis. One child was referred later for a retracted bladder with reflux. In one child, the lesion was promptly recognized and repaired. Of the four cases, two ruptures of the bladder caused transient sequaele, i.e. persisting catheter drainage, and voiding disorders later. In two cases, there were serious consequences: the bladder had to be partially removed in one child, ending up in temporary ureterostomy and subsequent reconstruction with bladder augmentation. The fourth child developed a small, water clock-shaped bladder with a thick wedge of scarred tissue, and bilateral ureteral reimplantation with bladder augmentation was necessary. Surgery of the inguinal canal is very common in children and infants, and is often performed by trainees. Awareness of this serious event should be emphasized in training programs.
Elimination of spurious eigenvalues in the Chebyshev Tau spectral method

Spectral methods have been used to great advantage in hydrodynamic stability calculations; the concepts are described in Orszag's seminal application of the Chebyshev tau method to the Orr-Sommerfeld equation for plane Poiseuille flow in 1971. Orszag discusses both the Chebyshev Galerkin and the Chebyshev tau methods, but presents results for the tau method, which is easier to implement than the Galerkin method. The tau method has the disadvantage that two unstable eigenvalues are produced that are artifacts of the discretization. An extremely simple modification to the Chebyshev tau method is presented which eliminates the spurious eigenvalues. First a simplified model of the Orr-Sommerfeld equation discussed by Gottlieb and Orszag was studied. Then the Chebyshev tau method is considered, which has two spurious eigenvalues, and then a modification which eliminates them is described. Finally, results for the Orr-Sommerfeld equation are considered where the modified tau method also eliminates the spurious eigenvalues. The simplicity of the modification makes it a convenient alternative to other approaches to the problem.
Distributed Robust Power System State Estimation

Deregulation of energy markets, penetration of renewables, advanced metering capabilities, and the urge for situational awareness, all call for system-wide power system state estimation (PSSE). Implementing a centralized estimator though is practically infeasible due to the complexity scale of an interconnection, the communication bottleneck in real-time monitoring, regional disclosure policies, and reliability issues. In this context, distributed PSSE methods are treated here under a unified and systematic framework. A novel algorithm is developed based on the alternating direction method of multipliers. It leverages existing PSSE solvers, respects privacy policies, exhibits low communication load, and its convergence to the centralized estimates is guaranteed even in the absence of local observability. Beyond the conventional least-squares based PSSE, the decentralized framework accommodates a robust state estimator. By exploiting interesting links to the compressive sampling advances, the latter jointly estimates the state and identifies corrupted measurements. The novel algorithms are numerically evaluated using the IEEE 14-, 118-bus, and a 4200-bus benchmarks. Simulations demonstrate that the attainable accuracy can be reached within a few inter-area exchanges, while largest residual tests are outperformed.
Zinc Carbenoid-mediated Chain Extension of β-Keto Amides

Abstract The reaction of β-keto amides with ethyl(iodomethyl)zinc provides access to a wide variety of γ-keto amides, including primary, secondary, and tertiary amides. Although the reaction of α-substituted β-keto amides are in many cases unsatisfactory, the method can be applied to a broad spectrum of substrates that possess imide and olefinic functionality.
Playing for Your Own Audience: Extremism in Two-Party Elections

This paper considers a two-party election with a single-dimensional policy space. We assume that each voter has a higher probability of observing the position of the party he is affiliated with than the position of the other party, an assumption that is consistent with the National Election Studies (NES) electoral data set. In equilibrium, the two parties locate away from the median, because the voters who dislike a party's platform observe its policy choice with a lower probability, and its own audience like policy choices that cater to its taste. As the asymmetry in voter information or the cost of voting increases, the parties adopt more extreme platforms, while if there are fewer extreme voters the opposite effect occurs. Making voters more symmetrically informed about the two parties' platforms increases the welfare of society, while asymmetric information acquisition by the voters is worse than no information acquisition at all.
Hybrid computer solutions of partial differential equations by Monte Carlo methods

In addition to finite-difference methods, Monte Carlo methods also are known for solving certain partial differential equations. When implemented on a digital computer, however, the Monte Carlo methods have generally proven to be very inefficient. In 1960, a study carried out at the University of Michigan described analog computer techniques for mechanizing Monte Carlo methods. From the Michigan study it became evident that a fast analog computer together with a small digital computer and a modest interface could obtain Monte Carlo solutions at rates competitive with standard finite-difference methods.
Fault Tolerant Implementation

In this paper we investigate the implementation problem arising when some of the players are “faulty” in the sense that they fail to act optimally. The planner and the non-faulty players only know that there can be at most k faulty players in the population. However, they know neither the identity of the faulty players, their exact number nor how faulty players behave. We define a solution concept which requires a player to optimally respond to the non-faulty players regardless of the identity and actions of the faulty players. We introduce a notion of fault tolerant implementation, which unlike standard notions of full implementation, also requires robustness to deviations from the equilibrium. The main result of this paper establishes that under symmetric information any choice rule that satisfies two properties— kmonotonicity and no veto power—can be implemented by a strategic game form if there are at least three players and the number of faulty players is less than 1 n 1. As an application of our result we present examples of simple mechanisms that implement the constrained Walrasian function and a choice rule for the efficient allocation of an indivisible good.
Who shapes network neutrality policy debate? An examination of information subsidizers in the mainstream media and at Congressional and FCC hearings

Recognizing policy-making process as a communicative process, this study examines who has subsidized information relating to the net neutrality policy debate. Empirical data has been collected from net neutrality stories published in four national newspapers, as well as from hearings by Congress and the Federal Communications Commission (FCC), during the period of February 2004 through January 2009. Study findings reveal that corporate interests have played a significant role in subsidizing information on net neutrality, both to the public through the mainstream media and to legislators through Congressional hearings. Furthermore, study results show that experts played a larger role in defining net neutrality through the mainstream media and FCC hearings than they did through Congressional hearings. Finally, the role of advocacy group representatives was more apparent at Congressional hearings than via the other two available information channels.
Dual-phase argon ionization detector for measurement of coherent elastic neutrino scattering and medium-energy nuclear recoils

We propose to build and deploy a 10-kg dual-phase argon ionization detector for the detection of coherent neutrino-nucleus scattering, which is described by the reaction; ( ν ) + ( Z , N ) → ( ν ) + ( Z , N ) . Our group would be the first to make this measurement. Its detection would validate (or refute) central tenets of the Standard Model. The existence of this process is also relevant to astrophysics, where coherent neutrino scattering is assumed to impede energy transport within neutron stars. We have built a gas-phase argon ionization detector to determine the feasibility of measuring small recoil energies (∼1keV) predicted from coherent neutrino scattering, and to characterize the recoil spectrum of the argon nuclei induced by scattering from medium-energy neutrons. We present calibrations made with 55-Fe, a low energy x-ray source, and describe a planned measurement of the recoil spectra from the 60keV Lithium-target neutron generator at LLNL. A high signal-to-noise measurement of the recoil spectrum will not only serve an important milestone in achieving the sensitivity necessary for measuring coherent neutrino-nucleus scattering, but will break new scientific ground by providing a first ever measurement of low-energy quenching factors in argon.
Computer simulation of the operations of utility grid connected photovoltaic power plants

In order to evaluate the commercial viability of photovoltaic power systems it is necessary to have reliable estimates and descriptions of the supply of electricity generated by the solar technology, the demand for that electricity, and the market application. A methodology which produces information on performance, cost, and value components of utility grid connected photovoltaic power plants has been developed to assist in these evaluations (References 1, 2). This report describes that analytical model and presents an application to a utility grid connected central power system with a range of operations alternatives.
Synthesis and anti-pneumocystis carinii activity of piperidine-linked aromatic diimidazolines

Abstract A series of novel piperidine-linked aromatic diimidazolines ( 3–7 ) have been synthesized as conformationally restricted congeners of the anti- Pneumocystis carinii drug, Pentamidine. These compounds significantly inhibited the growth of Pneumocystis carinii in culture at 1 μg/mL.