cssi/SciSciGPT-SciSciNet huggingface dataset:
Optimal sin taxes

Abstract We investigate “sin taxes” on unhealthy items, such as fatty foods, that people may (by their own reckoning) consume too much of. We employ a standard optimal-taxation framework, but replace the standard assumption that all consumers have 100% self control with an assumption that some consumers may have some degree of self-control problems. We show that imposing taxes on unhealthy items and returning the proceeds to consumers can generally improve total social surplus. Because such taxes counteract over-consumption by consumers with self-control problems while at the same time they naturally redistribute income to consumers with no self-control problems (who consume less), such taxes can even create Pareto improvements. Finally, we demonstrate with some simple numerical examples that even if the population exhibits relatively few self-control problems, optimal taxes can still be large.
Flexibly coupled multiprocessors for image processing

Abstract Two hardware mechanisms are mainly used for data sharing among processing elements in multiprocessors: message passing in loosely coupled multiprocessors and shared memory in tightly coupled multiprocessors. The former has communication overhead and the latter has shared memory contention. Moreover, in image processing, inefficient data input and output schemes are also limitations on performance. In this paper, Flexibly (Tightly/Loosely) Coupled Multiprocessors (FCM) for image processing are proposed in order to alleviate these disadvantages. A variable space memory scheme , in which a set of adjacent memory modules can be merged by a dynamically partitionable bus, is proposed to realize FCM. These architectures are quantitatively analyzed and simulated on the iPSC/1 (Intel's Personal SuperComputer), a hypercube multiprocessor. Parallel algorithms for region labeling and median filtering are simulated on the proposed architectures. The performance of FCM shows remarkable improvement over that of iPSC/1.
Gold(I)-Catalyzed Enantioselective Polycyclization Reactions

A series of enantioselective polycyclization reactions, catalyzed by a cationic bisphosphine gold complexes, are described. The polycyclization reactions, which employ an alkyne as an initiating group, begin with a gold-promoted 6-exo-dig cyclization and can be terminated with a variety of nucleophiles including carboxylic acids, phenols, sulfonamides, and electron-rich aryl groups. This method allows for the preparation of up to four bonds in a single operation with excellent diastereo- and enantioselectivity.
Catalytic Enantioselective Conjugate Reduction of Lactones and Lactams

A dramatic acceleration of the enantioselective copper-catalyzed conjugate reduction of α,β-unsaturated lactones, lactams, and esters is reported upon addition of alcohol additives. Good to excellent yields and enantioselectivities were realized using a catalyst generated in situ from CuCl2·H2O, t-BuONa, p-tol-BINAP, and PMHS, and this methodology was applied to the synthesis of (−)-Paroxetine.
Counterattack reagent bis(trimethylsilyl)acetamide in the disilylation of diols

The counterattack method was applied to the disilylation of diols. Treatment of various diols with 0.3 or 1.1 equivalents of potassium hydride and 1.1 equivalents of bis(trimethylsilyl)-acetamide in THF gave the corresponding disilyl ethers in good to excellent yields (60–95%). The diols may contain other functionalities, such as amide, amine, ether, and thioether. The diols used in the disilylation were 2a–14a. The newly developed disilylation proceeded in one flask by a sequential deprotonation-silylation-deprotonation-silylation pathway. This disilylation also represents an example of a “tandem double-counterattack process”. Bis(trimethylsilyl)-acetamide acted as a counterattack reagent; it provided two Me3Si groups to diols and produced amides as bases.
On the Performance of Adaptive Packetized Wireless Communication Links Under Jamming

We employ a game theoretic approach to formulate communication between two nodes over a wireless link in the presence of an adversary. We define a constrained, two-player, zero-sum game between a transmitter/receiver pair with adaptive transmission parameters and an adversary with average and maximum power constraints. In this model, the transmitter's goal is to maximize the achievable expected performance of the communication link, defined by a utility function, while the jammer's goal is to minimize the same utility function. Inspired by capacity/rate as a performance measure, we define a general utility function and a payoff matrix which may be applied to a variety of jamming problems. We show the existence of a threshold (J TH ) such that if the jammer's average power exceeds J TH , the expected payoff of the transmitter at Nash Equilibrium (NE) is the same as the case when the jammer uses its maximum allowable power, J max , all the time. We provide analytical and numerical results for transmitter and jammer optimal strategies and a closed form expression for the expected value of the game at the NE. As a special case, we investigate the maximum achievable transmission rate of a rate-adaptive, packetized, wireless AWGN communication link under different jamming scenarios and show that randomization can significantly assist a smart jammer with limited average power.
Sonoluminescence: Coupling to an applied magnetic field

Abstract We investigate several means of coupling between a sonoluminescing bubble and an applied magnetic field. Recent experiments show a strong quadratic dependence between the forcing pressures required for stable sonoluminescence and magnetic field amplitude. However, all coupling mechanisms calculated here for comparable magnetic fields involve energies no more than one percent the mechanical energy of bubble collapse. We conclude that the applied field must influence the system though its effect on some parameter which the bubble motion depends upon very sensitively. A few such mechanisms are suggested.
Naphthalene, Phenanthrene, and Pyrene as DNA Base Analogues: Synthesis, Structure, and Fluorescence in DNA

We describe the synthesis, structures, and DNA incorporation of deoxyribonucleosides carrying polycyclic aromatic hydrocarbons as the DNA "base" analogue. The new polycyclic compounds are 1-naphthyl, 2-naphthyl, 9-phenanthrenyl, and 1-pyrenyl deoxynucleosides. The compounds are synthesized using a recently developed C-glycosidic bond formation method involving organocadmium derivatives of the aromatic compounds coupling with a 1α-chlorodeoxyribose precursor. The principal products of this coupling are the α-anomers of the deoxyribosides. An efficient method has also been developed for epimerization of the α-anomers to β-anomers by acid-catalyzed equilibration; this isomerization is successfully carried out on the four polycyclic nucleosides as well as two substituted phenyl nucleosides. The geometry of the anomeric substitution is derived from (1)H NOE experiments and is also correlated with a single-crystal X-ray structure of one α-isomer. Three of the polycyclic C-nucleoside derivatives are incorporated into DNA oligonucleotides via their phosphoramidite derivatives; the pyrenyl and phenanthrenyl derivatives are shown to be fluorescent in a DNA sequence. The results (1) broaden the scope of our C-glycoside coupling reaction, (2) demonstrate that (using a new acid-catalyzed epimerization) both α- and β-anomers are easily synthesized, and (3) constitute a new class of deoxynucleoside derivatives. Such nucleoside analogues may be useful as biophysical probes for the study of noncovalent interactions such as aromatic π-stacking in DNA. In addition, the fluorescence of the phenanthrene and pyrene nucleosides may make them especially useful as structural probes.
Strictly regio- and stereo-controlled α-alkenylation of bicyclic enone derivatives via palladium-catalyzed cross coupling and its application to a formal synthesis of (±)-carbacyclin

Abstract A formal synthesis of carbacylin was achieved by preparing a known advanced intermediate 15 via Zr-promoted enyne bicyclization-carbonylation, Pd-catalyzed α-alkenylation of bicyclic enones, and conjugate reduction.
Dimethyl(methylthio)sulfonium tetrafluoroborate: A reagent for disulfide bond formation in peptides

Abstract Dimethyl(methylthio)sulfonium tetrafluoroborate (1) has been used to deprotect a series of cysteine derivatives (BocCys-Acm, MeOBzl, Trt) with concurrent disulfide bond formation. This reagent has also been applied to the deprotection and disulfide bond formation in two peptides: a sarafotoxin A fragment and an analog of calcitonin where each peptide contains two S-protected cysteine derivatives: [Cys(Acm)]
Parameter study of the LIFE engine nuclear design

Abstract LLNL is developing the nuclear fusion based Laser Inertial Fusion Energy (LIFE) power plant concept. The baseline design uses a depleted uranium (DU) fission fuel blanket with a flowing molten salt coolant (flibe) that also breeds the tritium needed to sustain the fusion energy source. Indirect drive targets, similar to those that will be demonstrated on the National Ignition Facility (NIF), are ignited at ∼13 Hz providing a 500 MW fusion source. The DU is in the form of a uranium oxycarbide kernel in modified TRISO-like fuel particles distributed in a carbon matrix forming 2-cm-diameter pebbles. The thermal power is held at 2000 MW by continuously varying the 6 Li enrichment in the coolants. There are many options to be considered in the engine design including target yield, U-to-C ratio in the fuel, fission blanket thickness, etc. Here we report results of design variations and compare them in terms of various figures of merit such as time to reach a desired burnup, full-power years of operation, time and maximum burnup at power ramp-down and the overall balance of plant utilization.
An Agent-Based Test Bed Study of Wholesale Power Market Performance Measures

Wholesale power markets operating over transmission grids subject to congestion have distinctive features that complicate the detection of market power and operational inefficiency. This study uses a "wholesale power market test bed "with strategically learning traders to experimentally test the extent to "which market performance measures commonly used for other industries are informative for the dynamic operation of restructured "wholesale power markets. Examined measures include the Herfindahl-Hirschman index (HHI), the Lerner index (LI), the residual supply index (RSI), the relative market advantage index (RMAI), and the operational efficiency index (OEI).
Proposed particle-beam characterizations for the APS undulator test line

Abstract A research and development effort is under way at the Advanced Photon Source (APS) to use an rf gun as a low-emittance electron source for injection into the 100- to 650-MeV linac subsystem and subsequent transport to an undulator test area. This configuration would combine the acceleration capability of the 200-MeV S-band electron linac and the in-line 450-MeV positron linac that normally provide positrons to the positron accumulator ring (PAR). A transport line that bypasses the PAR will bring the electrons to the undulator test area. Characterization techniques will be discussed for the electron beam with a normalized, rms emittance of π mm mrad (1 σ ) at micropulse charges of up to 350 pC and micropulse durations of ∼ 5 ps (FWHM). Tests proposed include measurement of particle beam transport effects (at one-tenth the storage ring beam rigidity) caused by small undulator field errors as well as operations intended to produce diffraction-limited and possibly even coherent, short wavelength radiation (
The Limits of Transparency

Transparency is viewed as a self-evident good in Western society. Etzioni reexamines the theoretical assumptions underlying the thesis that transparency plays a major role in holding democratic governments accountable. His analysis reveals that transparency plays a much smaller role than is often assumed. In addition, Etzioni finds that transparency cannot be relied upon to replace regulation, both because it is, itself, a form of regulation and because of the way in which democracies actually function. In assessing transparency, one must take into account a continuum composed of the order of disutility and the level of information costs. The higher the score on both variables, the less useful transparency is. Moreover, these scores need not be particularly high to greatly limit the extent to which the public can rely on transparency for most purposes.
The Chandlerian corporation and the theory of innovative enterprise

Through the synthesis of business history into a coherent and powerful analytical framework, Alfred Chandler made an enduring intellectual contribution to the social sciences. This essay outlines the implications of Chandler’s perspective for the theory of innovative enterprise, embeds that theory in the “social conditions of innovative enterprise” analytical framework, demonstrates the illogic of the neoclassical “monopoly model”, and contends that the analysis of the dynamics and performance of industrial capitalism requires a methodology that integrates theory and history.
Low-scale technicolor at the Tevatron

Abstract In multiscale models of walking technicolor, relatively light color-singlet technipions are produced in q q annihilation in association with longitudinal W and Z bosons and with each other. The technipions decay as π T 0 → b b and π T + → c b . Their production rates are resonantly enhanced by isovector technirho vector mesons with mass M W + M πT ≲ M ϱT ≲ 2 M πT . At the Tevatron, these associated production rates are 1–10 picobarns for M πT ⋍ 100 GeV . Such a low mass technipion requires topcolor-assisted technicolor to suppress the decay t → π T + b . Searches for πTπT production will also be rewarding. Sizable rates are expected if M ϱT ≳ 2 M πT + 10 GeV. The isoscalar ωT is nearly degenerate with ϱT and is expected to be produced at roughly the same rate. The ωT should have the distinctive decay modes ωT → γπ T 0 and Zπ T 0 .
Effect of inoculum/substrate ratio on methane yield and production rate from straw

Abstract This study evaluated the effect of inoculum/substrate ration on methane yield and production rate in small-batch fermentors. Four trials were conducted with substrate concentrations of 10, 20, 30 or 40 g ball-milled straw diluted with tap water to a total weight of 1 kg. Inoculum concentrations were: 100 (control), 90, 70, 50, 30 and 20 or 10% by volume. Results showed that the ultimate methane yield was drastically lower at inoculum/substrate ratios (on a volatile solids basis) below 0·25. Methane production rate increased at a decreasing rate up to an inoculum/substrate ratio of two, after which it remained relatively constant.
Cubic Irrationals and Periodicity via a Family of Multi-dimensional Continued Fraction Algorithms

We construct a countable family of multi-dimensional continued fraction algorithms, built out of five specific multidimensional continued fractions, and find a wide class of cubic irrational real numbers \(\alpha \) so that either \((\alpha , \alpha ^2)\) or \((\alpha , \alpha -\alpha ^2)\) is purely periodic with respect to an element in the family. These cubic irrationals seem to be quite natural, as we show that, for every cubic number field, there exists a pair \((u, u')\) with \(u\) a unit in the cubic number field (or possibly the quadratic extension of the cubic number field by the square root of the discriminant) such that \((u, u')\) has a periodic multidimensional continued fraction expansion under one of the maps in the family generated by the initial five maps. These results are built on a careful technical analysis of certain units in cubic number fields and our family of multi-dimensional continued fractions. We then recast the linking of cubic irrationals with periodicity to the linking of cubic irrationals with the construction of a matrix with nonnegative integer entries for which at least one row is eventually periodic.
Chiral transition and deconfinement transition in QCD with the highly improved staggered quark (HISQ) action

We report preliminary results on the chiral and deconfinement aspects of the QCD transition at finite temperature using the Highly Improved Staggered Quark (HISQ) action on lattices with temporal extent of N{sub {tau}} = 6 and 8. The chiral aspects of the transition are studied in terms of quark condensates and the disconnected chiral susceptibility. We study the deconfinement transition in terms of the strange quark number susceptibility and the renormalized Polyakov loop. We made continuum estimates for some quantities and find reasonably good agreement between our results and the recent continuum extrapolated results obtained with the stout staggered quark action.
Analysis of adhesion and interface debonding in laminated safety glass

Abstraet-A tension adhesion test is developed and analyzed to characterize polymer/glass adhesion in laminated safety glass. Laminated safety glass typically consists of two sheets of glass bonded by a polymer adhesive interlayer, usually plasticized poly(vinyl butyral). In the tension test, a rectangular laminate specimen is cracked on both glass sides, and loaded under a remote tension P at a constant displacement rate. The load on the specimen typically rises to a peak or deflection point load, P*, and the value of P* depends on the adhesion between the polymer interlayer and the glass. The peak load P* can be used as a characterization of the adhesion strength of the interface, but does not give a sample geometry-independent value for the adhesion. However, using a micromechanical model of debonding and a detailed finite element computation, the experimental data can be analyzed to determine the fracture toughness, and shear and normal strengths of the interface. The relationship between the peak load...
Coupled modal sliding mode control of vibration in flexible structures

The sliding mode control algorithm is developed for the coupled modal space control of a flexible structure when the bounds on the system parameters' errors are known. An explicit method to construct the desired sliding hyperplanes for the coupled modal sliding mode control is formulated. A boundary layer is used around each sliding hyperplane to eliminate the chattering phenomenon. Three types of steady-state solutions for the closed-loop system inside the boundary layers are found: the zero solution (origin of the state space), the constant nonzero solution, and the limit cycle. The amplitudes, phase angles, and the frequency of the limit cycle have been estimated by the describing function approach. The modal displacements corresponding to the constant nonzero solution have been obtained analytically. The stability of the zero solution has been examined by the linearized system analysis. Using a flexible tetrahedral truss structure, numerical examples are presented to verify the theoretical analyses.
Effect of non-local electron conductivity on power absorption and plasma density profiles in low pressure inductively coupled discharges

A self-consistent one-dimensional model was developed to study the effects of non-local electron conductivity on power absorption and plasma density profiles in a planar inductively coupled argon discharge at low pressures (≤10 mTorr). The model consisted of three modules: (1) an electron energy distribution function (EEDF) module to compute the non-Maxwellian EEDF, (2) a non-local electron kinetics module to predict the non-local electron conductivity, radio frequency (RF) current, electric field and power deposition profiles in the non-uniform plasma, and (3) a heavy species transport module to solve for the ion density and velocity profiles as well as the metastable density. Results using the non-local electron conductivity model were compared with predictions of a local theory (Ohm's law), under otherwise identical conditions. The RF current, electric field, and power deposition profiles were very different, especially at 1 mTorr for which the effective electron mean free path was larger than the skin depth. However, the plasma density profiles were almost identical (within 10%) for the same total power deposition in the plasma. This result suggests that, for computing plasma density profiles, a local conductivity model (Ohm's law), with much reduced computational expense, may be employed even in the non-local regime.
The mean flow character of two-phase flow equations

Abstract This study examines the nature of the one-dimensional mean motion description for two-phase flows. It is conjectured that the unstable wave growth in a streaming two-phase flow with unequal phasic velocities is a result of the failure to model the correlations of the fluctuating velocity components in the momentum equations. A general functional form for these velocity correlations is derived based upon invariance and dimensional arguments. Some speculative closure models using this functional form are derived and it is shown that reasonable forms of this closure model do in fact lead to a stable mean motion description.
A syndrome of congenital cardiomyopathy with mitral regurgitation, complete heart block and atrial arrhythmia

Abstract A distinctive syndrome of cardiomyopathy with mitral regurgitation, complete heart block and atrial arrhythmia was noted in four male patients aged 19 to 49 years. Each presented with cardiac enlargement and varying degrees of left ventricular failure. One patient was known to have had complete heart block from infancy and another patient from 13 years of age. Each had chronic atrial fibrillation or flutter, with a regular ventricular rhythm at 35 to 45/min. Hemodynamic studies showed dilatation and poor contractility of the left ventricle, considerable mitral regurgitation, reduced resting cardiac output and elevated left ventricular end-diastolic pressures. The clinical course in follow-up periods of up to 5 years has been one of relatively mild, slowly progressive congestive heart failure. Mitral valve replacement and permanent pacemaker installation in one patient had no effect on the clinical course. The mitral valve showed redundant leaflet tissue with mucoid degenerative changes. This syndrome appears to represent a form of congenital cardiomyopathy which involves degeneration or fibrotic changes in both the myocardium and the conduction system. Familial occurrence has not been recognized.
A COMPARISON INEQUALITY FOR SUMS OF INDEPENDENT RANDOM VARIABLES

Abstract We give a comparison inequality that allows one to estimate the tail probabilities of sums of independent Banach space valued random variables in terms of those of independent identically distributed random variables. More precisely, let X 1 ,…, X n be independent Banach-valued random variables. Let I be a random variable independent of X 1 ,…, X n and uniformly distributed over {1,…, n }. Put X 1 = X I , and let X 2 ,…, X n be independent identically distributed copies of X 1 . Then, P (‖ X 1 + ··· + X n ‖ ≥ λ) ≤ cP (‖ X 1 + ··· + X n ‖ ≥ λ/ c ) for all λ ≥ 0, where c is an absolute constant.
Cofacial cyclopentadienes. Synthesis and reactions of 1,8-bis(cyclopentadienyl)naphthalene

Abstract The reaction of Cyclopentadienylcopper·SMe 2 with 1,8-diiodonaphthalene gives 1,8-bis(cyclopentadienyl)naphthalene 3 , which undergoes a sigmatropic shift followed by an intramolecular Diels-Alder reaction, yielding the dicyclopentadiene 5 . Cycloreversion of 5 in the presence of sodium hydride, and trapping of the dianion with ferrous chloride, gives the bridged ferrocene 11 .
(2, 2) supergravity in the light-cone gauge

Abstract Starting with the prepotential description of two-dimensional (2,2) supergravity we use local supersymmetry transformations to go to light-cone gauge. We discuss properties of the theory in this gauge and derive Ward identities for correlation functions defined with respect to the induced supergravity action.
What everybody should know about translation

The author argues that translation, whether literary or technical, is a creative art, not a mechanical process, and machines have failed to give useful translations of serious texts for this reason. The conventional distinctions between `literary' and `technical' translation are misleading and perhaps false. Literal or word-for-word translations are not translations at all and their use should be discouraged. Translation requires a full command of both languages and some understanding of the subject. Quality is difficult for a layman to judge, but idiomatic English (or whatever the target language is) is one good sign, and there are others.
Aluminum-containing intergranular phases in hot-pressed silicon carbide

Using transmission electron microscopy, we studied aluminum-containing intergranular phases and secondary-phase particles at triple-junctions in SiC (hot-pressed with aluminum, boron, and carbon additions). This study of statistical high-resolution electron microscopy of intergranular films indicated that a large fraction of the vitreous intergranular films (in the as-hot-pressed SiC) crystallized during post-annealing in argon above 1000 °C. However, brief heating to 1900 °C indeed re-melted 25% of the crystallized intergranular films. The structural transitions were reflected in the statistical width distributions of the amorphous grain-boundary layers. At triple-junctions, Al2O3, Al2OC-SiC solid solution, and mullite phases were newly identified. These phases, together with others reported before, are represented in a quaternary phase diagram for 1900 °C. It is proposed that a SiC-Al2OC liquid domain should be included in this phase diagram.
CONVECTION THEORY AND SUB-PHOTOSPHERIC STRATIFICATION

As a preliminary step toward a complete theoretical integration of three-dimensional compressible hydrodynamic simulations into stellar evolution, convection at the surface and sub-surface layers of the Sun is re-examined, from a restricted point of view, in the language of mixing-length theory (MLT). Requiring that MLT use a hydrodynamically realistic dissipation length gives a new constraint on solar models. While the stellar structure which results is similar to that obtained by Yale Rotational Evolution Code (Guenther et al.; Bahcall & Pinsonneault) and Garching models (Schlattl et al.), the theoretical picture differs. A new quantitative connection is made between macro-turbulence, micro-turbulence, and the convective velocity scale at the photosphere, which has finite values. The geometric parameter in MLT is found to correspond more reasonably with the thickness of the superadiabatic region (SAR), as it must for consistency in MLT, and its integrated effect may correspond to that of the strong downward plumes which drive convection (Stein & Nordlund), and thus has a physical interpretation even in MLT. If we crudely require the thickness of the SAR to be consistent with the geometric factor used in MLT, there is no longer a free parameter, at least in principle. Use of three-dimensional simulations of both adiabatic convection and stellar atmospheres will allow the determination of the dissipation length and the geometric parameter (i.e., the entropy jump) more realistically, and with no astronomical calibration. A physically realistic treatment of convection in stellar evolution will require substantial additional modifications beyond MLT, including nonlocal effects of kinetic energy flux, entrainment (the most dramatic difference from MLT found by Meakin & Arnett), rotation, and magnetic fields.
Specifying Linepipe Suitable for Safe Operation in Sour, Wet Service

This paper describes the specifications recommended by the authors for buying linepipe in grades up to X-70 for wet, sour service. The linepipe is tested to verify that it is resistant to hydrogen-induced cracking (HIC). In addition, fracture control requirements are imposed so that if a failure does occur for any reason, the crack is guaranteed to self arrest, thus minimizing the consequences of the failure. Pipe meeting the specifications described in this paper is readily available from numerous European and Japanese mills.
Total synthesis and structural revision of engelhardione

The total synthesis of the macrocyclic natural product engelhardione is reported. This effort led to the structural revision of the published structure of engelhardione to that of pterocarine. The revision reflects the change of the substitution pattern of one phenyl ether ring from the meta to the para position. To confirm, pterocarine (2) and its close regioisomer 3 were subsequently synthesized for comparison. Moreover, to the best of our knowledge, our synthesis of 1 represents the first example of a 14-membered macrocyclic diarylheptanoid with a meta–meta substitution pattern at the diphenyl ether moiety.
Initiation and growth of martian ice lenses

Abstract Water ice in the upper meters of the martian regolith is a major volatile reservoir. Although the geographic extent, burial depth, and thermal stability of this shallow ice are well understood, its origin, history, and stratigraphy are not. Over the past decade, a growing body of observational evidence has indicated that shallow ground ice exceeds the pore volume of its host soil over large regions of both martian hemispheres. This is confounding, given that (1) the physical theory that accurately predicts the location of ground ice also assumes that ice should be pore-filling in the upper meter of regolith, and (2) the Phoenix spacecraft uncovered far more pore-filling ice than excess ice at its landing site in the northern hemisphere. The development of ice lenses by low-temperature in situ segregation – analogous to the processes that generate frost heave on Earth – has been hypothesized to explain shallow excess ice on Mars. We have developed a numerical model of ice lens initiation and growth in the martian environment, and used it to test this hypothesis for the first time. We carried out a large suite of numerical simulations in order to place quantitative constraints on the timing and location of ice lens initiation, and on the magnitude of ice lens growth in a variety of host soils. We find that ice lens initiation is a ubiquitous process in the martian high latitudes, but the ultimate magnitude of lens growth, or frost heave, is sensitive to the properties of the host soil. Depending on the specific properties of martian soils, in situ segregation may be a very slow process sufficient to explain the excess ice observed in the Dodo–Goldilocks trench at the Phoenix landing site, but without regionally significant effects. Alternatively, if clay-sized particles or perchlorate salts are present, in situ segregation may be a vigorous process that has significantly affected the stratigraphy of ground ice in the upper meter of regolith throughout the high latitudes.
Job Creation and Labor Reform in Latin America

This paper studies the effects of labor-regulation reform using data for 10,396 firms from 14 Latin American countries. Firms are asked both how many permanent workers they would have hired and how many they would have terminated if labor regulations were made more flexible. I find that making labor regulations more flexible would lead to an average net increase of 2.08 percent in total employment. Firms with fewer than 20 employees would benefit the most, with average gains in net employment of 4.27 percent. Countries with more regulated labor markets would experience larger gains in total employment. These larger gains in total employment, however, would be achieved through higher rates of hiring and higher rates of termination. These results may explain why there is substantial opposition to labor reforms despite the predicted gains in efficiency and total employment.
Approximate graph coloring by semidefinite programming

We consider the problem of coloring k-colorable graphs with the fewest possible colors. We present a randomized polynomial time algorithm that colors a 3-colorable graph on n vertices with min{O(D1/3 log1/2 D log n), O(n1/4 log1/2n)} colors where D is the maximum degree of any vertex. Besides giving the best known approximation ratio in terms of n, this marks the first nontrivial approximation result as a function of the maximum degree D. This result can be generalized to k-colorable graphs to obtain a coloring using min{O(D1-2/k log1/2 D log n), O(n1−3/(k+1) log1/2n)} colors. Our results are inspired by the recent work of Goemans and Williamson who used an algorithm for semidefinite optimization problems, which generalize linear programs, to obtain improved approximations for the MAX CUT and MAX 2-SAT problems. An intriguing outcome of our work is a duality relationship established between the value of the optimum solution to our semidefinite program and the Lovasz t-function. We show lower bounds on the gap between the optimum solution of our semidefinite program and the actual chromatic number; by duality this also demonstrates interesting new facts about the t-function.
Space Shuttle Flutter as Affected by Wing-Body Aerodynamic Interaction

In the NASA Langley Research Center 26-inch transonic blowdown wind-tunnel, flutter speeds were measured on 1/80-th scale semispan models of the orbiter wing, the complete Space Shuttle, and intermediate component combinations. Using the doublet lattice method combined with slender body theory to calculate unsteady aerodynamic forces, subsonic flutter speeds were computed for comparison. Aerodynamic interaction was found by test and analysis to raise the flutter speed in some configurations while lowering it in others. Although at Mach number less than 0.7, predicted speeds correlated to within 6% of those measured, rapid deterioration of the agreement occurred at higher subsonic Mach numbers, especially on the more complicated configurations. Additional analysis showed that aerodynamic forces arising from body flexibility potentially can have a large effect on flutter speed, but that the current shuttle design is not so affected.
Perturbation analysis of a clearance-type nonlinear system

Abstract This study applies the method of multiple scales to obtain periodic solutions of a two-pulley belt system with clearance-type nonlinearity. The purpose is to explain the published numerical results and clarify how design parameters affect the system dynamics. The validity of the perturbation method for such strong nonlinearity is evaluated. The closed-form frequency–response relation is determined at the first order, and an implicit expression is obtained for the second-order approximation. The preload applied to the accessory determines the softening level of the nonlinearity. Larger preload leads to less disengagement and less softening. For a considerable range of practical parameter values, the analytical solutions well approximate the numerical results from harmonic balance.
Dynamic Queuing Network Model for Flow Contingency Management

We introduce a queuing network model that can comprehensively represent traffic flow dynamics and flow management capabilities in the U.S. National Airspace System (NAS). We envision this model as a framework for tractably evaluating and designing coordinated flow management capabilities at a multi-Center or even NAS-wide spatial scale and at a strategic (2-15 h) temporal horizon. As such, the queuing network model is expected to serve as a critical piece of a strategic flow contingency management solution for the Next Generation Air Traffic System (NextGen). Based on this perspective, we outline, in some detail, the evaluation and design tasks that can be performed using the model, as well as the construction of the flow network underlying the model. Finally, some examples are presented, including one example that replicates traffic in Atlanta Center on an actual bad-weather day, to illustrate simulation of the model and interpretation/use of model outputs.
The Doomsday Argument and the Number of Possible Observers

If the human race comes to an end relatively shortly, then we have been born at a fairly typical time in the history of humanity; if trillions of people eventually exist, then we have been born in the first surprisingly tiny fraction of all people. According to the ‘doomsday argument’ of Carter, Leslie, Gott and Nielsen, this means that the chance of a disaster which would obliterate humanity is much larger than usually thought. But treating possible observers in the same way as those who actually exist avoids this conclusion: our existence is more likely in a race which is long-lived, and this cancels out the doomsday argument, so that the chance of a disaster is only what one would ordinarily estimate.
Effective action of spontaneously broken gauge theories

The effective action of a Higgs theory should be gauge-invariant. However, the quantum and/or thermal contributions to the effective potential seem to be gauge-dependent, posing a problem for its physical interpretation. In this paper, we identify the source of the problem and argue that in a Higgs theory perturbative contributions should be evaluated with the Higgs fields in the polar basis, not in the Cartesian basis. Formally, this observation can be made from the derivation of the Higgs theorem, which we provide. We show explicitly that, properly defined, the effective action for the Abelian Higgs theory is gauge-invariant to all orders in perturbation expansion when evaluated in the covariant gauge in the polar basis. In particular, the effective potential is gauge-invariant. We also show the equivalence between the calculations in the covariant gauge in the polar basis and the unitary gauge. These points are illustrated explicitly with the one-loop calculations of the effective action. With a field redefinition, we obtain the physical effective potential. The SU(2) non-Abelian case is also discussed.
Lower bounds for computations with the floor operation

A general lower bound technique is developed for computation trees with operations $\{ + , - , * ,/,\lfloor \cdot \rfloor , < \} $ and constants $\{ 0,1\} $, for functions that have as their input a single n-bit integer. The technique applies to many natural functions, such as perfect square root (deciding if the square root of the input is integral or not), computing the parity of $\lfloor {\log x} \rfloor $ , etc. The arguments are then extended to obtain the same lower bounds on the time complexity of any RAM program with operations $\{ + , - , * ,/,\lfloor \cdot \rfloor , < \} $ that solves the problem. Another related result is described in a companion paper [Proc. 29th IEEE Symposium on Foundations of Computer Science, 1988] and [J. Assoc. Comput. Mach., 1991, to appear].
Concurrent processing adaptation of aeroelastic analysis of propfans

Abstract This paper reports on a study involving the adaptation of an advanced aeroelastic analysis program to run concurrently on a shared memory multiple processor computer. The program uses a three-dimensional compressible unsteady aerodynamic model and blade normal modes to calculate aeroelastic stability and response of propfan blades. The identification of the computational parallelism within the sequential code and the scheduling of the concurrent subtasks to minimize processor idle time are discussed. Processor idle time in the calculation of the unsteady aerodynamic coefficients was reduced by the simple strategy of appropriately ordering the computations. Speedup and efficiency results are presented for the calculation of the matched flutter point of an experimental propfan model. The results show that efficiencies above 70% can be obtained using the present implementation with seven procesors. The parallel computational strategy described here is also applicable to other aeroelastic analysis procedures based on panel methods.
Fluorous benzaldehyde-based synthesis of biaryl-substituted oxazabicyclo[3.3.1]nonanes

Fluorous benzaldehyde-based synthesis of biaryl-substituted oxazabicyclo[3.3.1]nonanes is accomplished by a three-step synthesis including multicomponent reaction (MCR) to form tetrahydroquinoline, followed by cycloaddition with coumarin to form oxazabicycles, and then a Suzuki coupling to introduce the biaryl group. Microwave irradiation and fluorous solid-phase extraction (F-SPE) are employed to speed up reactions and simplify product purification.
Space performance of the multistage labyrinthine SMEI baffle

The Solar Mass Ejection Imager (SMEI) was launched on 6 January 2003, and shortly thereafter raised to a nearly circular orbit at 840 km. Three SMEI CCD cameras on the zenith-nadir oriented CORIOLIS spacecraft cover most of the sky beyond about 20°. from the Sun, each 102-minute orbit. Data from this instrument provide precision visible-light photometric sky maps. Once starlight and other constant or slowly varying backgrounds are subtracted, the residue is mostly sunlight that has been Thomson-scattered from heliospheric electrons. These maps enable 3-dimensional tomographic reconstruction of heliospheric density and velocity. This analysis requires 0.1% photometry and background-light reduction below one S10 (the brightness equivalent of a 10th magnitude star per square degree). Thus 10-15 of surface-brightness reduction is required relative to the solar disk. The SMEI labyrinthine baffle provides roughly 10-10 of this reduction; the subsequent optics system provides the remainder. We analyze data obtained over two years in space, and evaluate the full system's stray-light rejection performance.
Tree Particle-Mesh: An Adaptive, Efficient, and Parallel Code for Collisionless Cosmological Simulation

An improved implementation of an N-body code for simulating collisionless cosmological dynamics is presented. TPM (tree particle-mesh) combines the PM method on large scales with a tree code to handle particle-particle interactions at small separations. After the global PM forces are calculated, spatially distinct regions above a given density contrast are located; the tree code calculates the gravitational interactions inside these denser objects at higher spatial and temporal resolution. The new implementation includes individual particle time steps within trees, an improved treatment of tidal forces on trees, new criteria for higher force resolution and choice of time step, and parallel treatment of large trees. TPM is compared to P3M and a tree code (GADGET) and is found to give equivalent results in significantly less time. The implementation is highly portable (requiring a FORTRAN compiler and MPI) and efficient on parallel machines. The source code can be found on the World Wide Web.
A comparison of constant stimuli and gray‐scale methods of color difference scaling

Two psychophysical techniques, the method of constant stimuli and the gray-scale comparison method, were used to determine color tolerances for three different color centers in the hue, chroma, and lightness directions in CIELAB color space. The same color-difference pairs were used as the stimuli in both experiments. Although the results followed the same trends, they were different for the two techniques. Based on comparison of the validity and precision of the results, as well as the ease of implementation, use, and analysis, the method of constant stimuli is the preferable method. © 2002 Wiley Periodicals, Inc. Col Res Appl, 28, 36–44, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.
Reflection functors and symplectic reflection algebras for wreath products

We construct reflection functors on categories of modules over deformed wreath products of the preprojective algebra of a quiver. These functors give equivalences of categories associated to generic parameters which are in the same orbit under the Weyl group action. We give applications to the representation theory of symplectic reflection algebras of wreath product groups.
Experimental Realization of Popper's Experiment: Violation of the Uncertainty Principle?

An entangled pair of photon 1 and 2 are emitted in opposite directions along the positive and negative x-axis. A narrow slit is placed in the path of photon 1 which provides precise knowledge about its position along the y-axis and because of the quantum entanglement this in turn provides precise knowledge of the position y of its twin, photon 2. Does photon 2 experience a greater uncertainty in its momentum, i.e., a greater Δp y , due to the precise knowledge of its position y? This is the historical thought experiment of Sir Karl Popper which was aimed to undermine the Copenhagen interpretation in favor of a realistic viewpoint of quantum mechanics. Thispaper reports an experimental realization of the Popper’s experiment. One may not agree with Popper’s position on quantum mechanics; however, it calls for a correct understanding and interpretation of the experimental results.
Relativistic Accretion Disk Models of High-State Black Hole X-Ray Binary Spectra

We present calculations of non-LTE, relativistic accretion disk models applicable to the high/soft state of black hole X-ray binaries. We include the effects of thermal Comptonization and bound-free and free-free opacities of all abundant ion species. Taking into account the relativistic propagation of photons from the local disk surface to an observer at infinity, we present spectra calculated for a variety of accretion rates, black hole spin parameters, disk inclinations, and stress prescriptions. We also consider nonzero inner torques on the disk and explore different vertical dissipation profiles, including some that are motivated by recent radiation magnetohydrodynamic (MHD) simulations of magnetorotational turbulence. Bound-free metal opacity generally produces significantly less spectral hardening than previous models that only considered Compton scattering and free-free opacity. We find that the resulting effective photosphere usually lies at a small fraction of the total column depth, producing spectra that are remarkably independent of the stress prescription and vertical structure assumptions. We provide detailed comparisons between our models and the widely used multicolor disk model. Frequency-dependent discrepancies exist that may affect the parameters of other spectral components when this simpler disk model is used to fit modern X-ray data. For a given source, our models predict that the luminosity in the high/soft state should approximately scale with the fourth power of the empirically inferred maximum temperature, but with a slight hardening at high luminosities. This is in good agreement with observations.
Conformational Analysis and a Crystal Structure of Bupropion, an Antidepressant with Dopamine Reuptake Blocking Activity

A conformational analysis has been performed on the antidepressant bupropion using the MM3-92 program. In addition, the structure of the compound in the crystal state was obtained. There is good agreement between the computed global minimum and the structure observed by crystallography. The three-dimensional structure of the preferred conformer of bupropion is consistent with the three-dimensional structures of other dopamine reuptake blockers such as cocaine, CFT, and methylphenidate.
Zeros of Non-Baxter Paraorthogonal Polynomials on the Unit Circle

We provide leading-order asymptotics for the size of the gap in the zeros around 1 of paraorthogonal polynomials on the unit circle whose Verblunsky coefficients satisfy a slow decay condition and are inside the interval (−1,0). We also include related results that impose less restrictive conditions on the Verblunsky coefficients.
Sensitivity parameter and time variations of fundamental constants

The sensitivity parameter is widely used for quantifying fine tuning. However, examples show it fails to give correct results under certain circumstances. We argue that the problems of the sensitivity parameter are almost identical to the consequences we have to solve if the time-varying fine structure constant is proved to be true. The high sensitivity of the energy scale parameter Λ to the dimensionless coupling constant plays an important role in these problems. It affects the reliability of the sensitivity parameter via mechanisms such as dynamical symmetry breaking, chiral symmetry breaking, etc. The reliability of the sensitivity parameter can be improved if it is used properly.