cssi/SciSciGPT-SciSciNet huggingface dataset:
Extracting Muon Momentum Scale Corrections for Hadron Collider Experiments

We present a simple method for the extraction of corrections for bias in the measurement of the momentum of muons in hadron collider experiments. Such bias can originate from a variety of sources such as detector misalignment, software reconstruction bias, and uncertainties in the magnetic field. The two step method uses the mean $\langle1/p^{\mu}_{T} \rangle$ for muons from Z→μμ decays to determine the momentum scale corrections in bins of charge, η and ϕ. In the second step, the corrections are tuned by using the average invariant mass $\langle M^{Z}_{\mu\mu }\rangle$ of Z→μμ events in the same bins of charge η and ϕ. The forward–backward asymmetry of Z/γ ∗→μμ pairs as a function of μ + μ − mass, and the ϕ distribution of Z bosons in the Collins–Soper frame are used to ascertain that the corrections remove the bias in the momentum measurements for positive versus negatively charged muons. By taking the sum and difference of the momentum scale corrections for positive and negative muons, we isolate additive corrections to $1/p^{\mu}_{T}$ that may originate from misalignments and multiplicative corrections that may originate from mis-modeling of the magnetic field (∫B⋅d L). This method has recently been used in the CDF experiment at Fermilab and in the CMS experiment at the Large Hadron Collider at CERN.
Methodological aspects of anti-human leukocyte antigen antibody analysis in solid organ transplantation

Donor human leukocyte antigen (HLA)-specific antibodies (DSA) play an important role in solid organ transplantation. Preexisting IgG isotype DSA are considered a risk factor for antibody mediated rejection, graft failure or graft loss. The post-transplant development of DSA depends on multiple factors including immunogenicity of mismatched antigens, HLA class II typing of the recipient, cytokine gene polymorphisms, and cellular immunoregulatory mechanisms. De novo developed antibodies require special attention because not all DSA have equal clinical significance. Therefore, it is important for transplant clinicians and transplant immunologists to accurately characterize DSA. In this review, the contemporary immunological techniques for detection and characterization of anti-HLA antibodies and their pitfalls are described.
Ex ante basis risk in the live hog futures contract: Has hedgers' risk increased?

Basis behavior can have a direct affect on hedging and pricing decisions. Here, ex ante basis risk for selected live hog cash markets is analyzed from 1985 through 1994. One and five month ahead econometric, time series, and naive forecasts are used to construct measures of basis risk based on mean squared forecast errors and market timing ability. The findings suggest that basis risk has not increased nor has basis predictability declined relative to historical levels. The recent decline in demand for futures contracts is likely attributable to other structural changes in the industry.
Simulation of a Controlled Airfoil with Jets

Numerical simulations of a two-dimensional airfoil, controlled by an applied moment in pitch and an airfoil controlled by jets, were investigated. These simulations couple the Reynolds-averaged Navier-Stokes equations and Euler''s equations of rigid body motion, with an active control system. Controllers for both systems were designed to track altitude commands and were evaluated by simulating a closed-loop altitude step response using the coupled system. The airfoil controlled by a pitching moment used an optimal state feedback controller. A closed-loop simulation, of the airfoil with an applied moment, showed that the trajectories compared very well with quasi-steady aerodynamic theory, providing a measure of validation. The airfoil with jets used a controller designed by robust control methods. A linear plant model for this system was identified using open-loop data generated by the nonlinear coupled system. A closed-loop simulation of the airfoil with jets, showed good tracking of an altitude command. This simulation also showed oscillations in the control input as a result of dynamics not accounted for in the control design. This research work demonstrates how computational fluid dynamics, coupled with rigid body dynamics, and a control law can be used to prototype control systems in problematic nonlinear flight regimes.
The large deviation principle for the Erdős-Rényi random graph

What does an Erdos-Renyi graph look like when a rare event happens? This paper answers this question when p is fixed and n tends to infinity by establishing a large deviation principle under an appropriate topology. The formulation and proof of the main result uses the recent development of the theory of graph limits by Lovasz and coauthors and Szemeredi's regularity lemma from graph theory. As a basic application of the general principle, we work out large deviations for the number of triangles in G(n,p). Surprisingly, even this simple example yields an interesting double phase transition.
Periodic solutions of Abel differential equations

For a class of polynomial non-autonomous differential equations of degree n, we use phase plane analysis to show that each equation in this class has n periodic solutions. The result implies that certain rigid two-dimensional systems have at most one limit cycle which appears through multiple Hopf bifurcation.
Non-contrast-enhanced pulmonary vein MRI with a spatially selective slab inversion preparation sequence.

We propose a non-contrast-enhanced, three-dimensional, free-breathing, electrocardiogram-gated, gradient recalled echo sequence with a slab-selective inversion for pulmonary vein (PV) MRI. A sagittal inversion slab was applied prior to data acquisition to suppress structures adjacent to the left atrium (LA) and PVs, thereby improving the conspicuity of the PV and LA. Compared with other MR angiography methods using an inversion pulse, the proposed method does not require signal subtraction and the inversion slab is not parallel to the imaging slab. The feasibility of the proposed method was demonstrated in healthy subjects. The inversion slab thickness and inversion time were optimized to be 60 mm and 500 ms, respectively. Compared to conventional gradient recalled echo imaging without inversion, the proposed technique significantly increased the contrast-to-noise ratios between the LA and the right atrium by 20-fold (P 0.3). The proposed technique greatly enhances the conspicuity of the PVs and LA without significant loss of signal-to-noise ratio.
Tracking of multiple maneuvering targets in clutter using multiple sensors, IMM, and JPDA coupled filtering

We consider the problem of tracking multiple maneuvering targets in clutter using switching multiple target motion models. A novel suboptimal filtering algorithm is developed by applying the basic interacting multiple model (IMM) approach, the joint probabilistic data association (JPDA) technique and coupled target state estimation to a Markovian switching system. The algorithm is illustrated via a simulation example involving tracking of two highly maneuvering, at times closely spaced, targets.
Morphology of galaxy mergers at intermediate redshift

Using a combination of numerical simulation and synthesized Hubble Space Telescope Wide Field Camera 2 (HST WFC2) images, we follow the detectability of morphological signatures of disk galaxy mergers at intermediate redshifts z = 0.4 and z = 1.0. Rapid evolution in the surface brightness of tidal tails makes their use as an interaction signature limited; long tidal tails will only be detectable relatively early in the encounter, before the galaxies actually merge. Violent relaxation rapidly smooths isophotal irregularities after the galaxies merge, leaving the very low surface brightness tidal debris surrounding the remnant as the only sign of peculiarity after a few hundred Myr. This debris becomes indistinguishable from the main body of the remnant after less than or approximately equal to 0.2 (z = 1.0) to 1 (z = 0.4) Gyr, leaving a morphologically normal elliptical galaxy behind. Using WFC1, all signatures become undetectable almost immediately once the galaxies merge, due to the aberrated Point Speed Function (PSF). We interpret these results in light of recent HST programs investigating the nature of starburst and E + A galaxies in moderate redshift clusters.
5-(Methylthio)tetrazoles as versatile synthons in the stereoselective synthesis of polycyclic pyrazolines via photoinduced intramolecular nitrile imine–alkene 1,3-dipolar cycloaddition

A key thioether substituent in readily accessible 2-alkyl-5-(methylthio)tetrazoles enables facile photoinduced denitrogenation and intramolecular nitrile imine 1,3-dipolar cycloaddition to afford a wide range of polycyclic pyrazoline products with excellent diastereoselectivity. The methylthio group red-shifts the UV absorbance of the tetrazole, obviating the requirement in all previous substrate systems for at least one aryl substituent, and can subsequently be converted into a variety of other functionalities. This synthetic platform has been applied to the concise total syntheses of the alkaloid natural products (±)-newbouldine and withasomnine.
Bubble Kinetics in a Steady-State Column of Aqueous Foam

We measure the liquid content, the bubble speeds, and the distribution of bubble sizes, in a vertical column of aqueous foam maintained in steady state by continuous bubbling of gas into a surfactant solution. Nearly round bubbles accumulate at the solution/foam interface, and subsequently rise with constant speed. Upon moving up the column, they become larger due to gas diffusion and more polyhedral due to drainage. The size distribution is monodisperse near the bottom and polydisperse near the top, but there is an unexpected range of intermediate heights where it is bidisperse with small bubbles decorating the junctions between larger bubbles. We explain the evolution in both bidisperse and polydisperse regimes, using Laplace pressure differences and taking the liquid fraction profile as a given.
A source of individual variation

Abstract Even though behavioral experiments are usually conducted in a manner that minimizes variance between subjects, such variance is unavoidable—even when working with a homogenous population. A first step in producing a quantitative understanding of what causes this variation is a biologically based neural network model that reproduces the observed individual differences. Here we show that a simple model of the hippocampus can reproduce the histogram of learned performance in a homogenous population. The task and data being fit is transitive inference that is learned by college students. Individual differences mainly arise from initial connectivity differences not neuronal state initializations.
Maternal electrocardiographic changes in the peripartum period

Continuous electrocardiographic monitoring was performed in 20 term parturients during labor, vaginal delivery, and recovery. Mean duration of monitoring was 13.37 h. Sinus tachycardia was seen in all parturients (mean maximum heart rate=138); in 8 patients (40%), maximum heart rate was not attained until 0.5-5 h after delivery. Eight patients exhibited premature ventricular contractions or supraventricular tachycardia. ST-segment depression was noted in 3 patients (15%); in all 3, this was concurrent with maximum heart rate, was not associated with any symptoms, and occurred in the post-partum period.
Optimization of the Individual Stiffness and Damping Parameters in Multiple-Tuned-Mass-Damper Systems

The characteristics of multiple tuned-mass-dampers (MTMDs) attached to a single-degree-of-freedom primary system have been examined by many researchers. Several papers have included some parameter optimization, all based on restrictive assumptions. In this paper, we propose an efficient numerical algorithm to directly optimize the stiffness and damping of each of the tuned-mass dampers (TMDs) in such a system. We formulate the parameter optimization as a decentralized H2 control problem where the block-diagonal feedback gain matrix is composed of the stiffness and damping coefficients of the TMDs. The gradient of the root-mean-square response with respect to the design parameters is evaluated explicitly, and the optimization can be carried out efficiently. The effects of the mass distribution, number of dampers, total mass ratio, and uncertainties in system parameters are studied. Numerical results indicate that the optimal designs have neither uniformly spaced tuning frequencies nor identical damping coefficients, and that optimization of the individual parameters in the MTMD system yields a substantial improvement in performance. We also find that the distribution of mass among the TMDs has little impact on the performance of the system provided that the stiffness and damping can be individually optimized.
Time-resolved self-assembly of a fullerene-topology core-shell cluster containing 68 uranyl polyhedra.

A complex core–shell cluster consisting of 68 uranyl peroxo polyhedra, 16 nitrate groups, and ∼44 K+ and Na+ cations was obtained by self-assembly in alkaline aqueous solution under ambient conditions. Crystals formed after a month and were characterized. The cluster, designated as {U1⊂U28⊂U40R}, contains a fullerene-topology cage built from 28 uranyl polyhedra. A ring consisting of 40 uranyl polyhedra linked into five-membered rings and 16 nitrate groups surrounds this cage cluster. Topological pentagons in the cage and ring are aligned, and their corresponding rings of uranyl bipyramids are linked through K+ cations located between the two shells. A partially occupied U site is located at the center of the cluster. Time-resolved small-angle X-ray scattering and electrospray ionization mass spectrometry demonstrated that the U28 cage cluster formed in solution within an hour, whereas the U40R shell formed around the cage cluster after more than several days.
Earth entry flight test of Mars entry vehicles.

System studies of Mars entry vehicles have shown that an Earth entry test could be used to demonstrate, in actual operation, the value of atmospheric sensing instrumentation systems to be used during descent into the Martian atmosphere, in its "proofing" of the operation of aerodynamic retardation systems, and in the demonstration of the communications link operation under actual conditions of vehicle motion and plasma sheath blackout. This paper discusses these factors and the limitations of the test, which include the "oversimulation" of the Mars entry heating profile and the high cost of full-scale tests of large entry systems. A hypothetical test program for a small (28 in.-diam, 30-lb) Mars atmospheric probe illustrates the application of this type of test, using a three-stage Scout as a launch vehicle.
Effect of compatibility of S-R mapping on reactions toward the stimulus source.

Abstract This research was concerned with separating the effects of three varieties of S-R compatibility: reactions toward the stimulus source, compatibility of S-R mapping, and display-control arrangement correspondence. In experiments 1 and 2, subjects pressed a green or red key located on the left and right in response to the onset of a green or red stimulus presented in a left or right window. Half of the subjects pressed the key which corresponded to the color of the stimulus (compatible S-R mapping) while the other half pressed the alternate colored key (incompatible S-R mapping). In the compatible mapping task, reactions were faster when location of stimulus and response corresponded than when they did not while, in the incompatible task, reactions were faster when location of stimulus and response did not correspond. This apparent reversal in the tendency to react toward the stimulus source was attributed to display- control arrangement correspondence rather than to logical recoding of the directional cue. Experiment 3 established that faster reactions toward the stimulus source occured only under compatible mapping instructions.
High‐resolution optical spectroscopy of a newly discovered post‐AGB star with a surprising metallicity in the globular cluster M79

An abundance analysis based on a high-resolution spectrum is presented for a newly discovered post-asymptotic giant branch (PAGB) star in the globular cluster M79. The surprising result is that the iron abundance of the star is apparently about 0.6 dex less than that of the cluster's red giants as reported by published studies including a recent high-resolution spectroscopic analysis by Carretta and colleagues. Abundances relative to iron appear to be the same for the PAGB star and the red giants for the 15 common elements. It is suggested that the explanation for the lower abundances of the PAGB star may be that its atmospheric structure differs from that of a classical atmosphere; the temperature gradient may be flatter than predicted by a classical atmosphere.
Geographic atrophy segmentation in infrared and autofluorescent retina images using supervised learning

Geographic Atrophy (GA) of the retinal pigment epithelium (RPE) is an advanced form of atrophic age-related macular degeneration (AMD) and is responsible for about 20% of AMD-related legal blindness in the United States. Two different imaging modalities for retinas, infrared imaging and autofluorescence imaging, serve as interesting complimentary technologies for highlighting GA. In this work we explore the use of neural network classifiers in performing segmentation of GA in registered infrared (IR) and autofluorescence (AF) images. Our segmentation achieved a performance level of 82.5% sensitivity and 92.9% specificity on a per-pixel basis using hold-one-out validation testing. The algorithm, feature extraction, data set and experimental results are discussed and shown.
On the Number of Inequivalent Binary Self-Orthogonal Codes

Let Psik,n denote the number of inequivalent binary self-orthogonal [n, k] codes. We present a method which allows us to compute Psik,n explicitly for a moderate k and an arbitrary n. Included in this paper are explicit formulas for Psik,n with k les 5.
Reversible covalent attachment of C60 to a furan-functionalized resin

Abstract Reaction of Merrifield's peptide resin with the sodium anion of furfuryl alcohol provides a furan-functionalized polymer resin. This polymer reacts rapidly with C 60 to provide a fullerene-substituted polymer, presumably via Diels-Alder reaction, with the furan as diene and the fullerene as dienophile. This resin is greater than two-fold more efficient in C 60 uptake, and provides a 66% increase in C 60 release upon heating, compared with the previously reported cyclopentadiene-functionalized resin.
Application of 1,2:5,6-di-O-cyclohexylidene-d-mannitol as the chiral director in Matteson’s asymmetric homologation

1,2:5,6-Di-O-cyclohexylidene-d-mannitol is the good chiral director in Matteson’s asymmetric homologation as indicated by the high enantiomeric excesses (ee’s) of the secondary alcohols produced by treatment of the homologation products with alkyllithium or Grignard reagents followed by oxidation.
HOUSING AND THE BUSINESS CYCLE

In the United States, the percentage standard deviation of residential investment is more than twice that of nonresidential investment. In addition, GDP, consumption, and both types of investment co-move positively. We reproduce these facts in a calibrated multisector growth model where construction, manufacturing, and services are combined, in different proportions, to produce consumption, business investment, and residential structures. New housing requires land in addition to new structures. The model can also account for important features of industry-level data. In particular, hours and output in all industries are positively correlated, and are most volatile in construction.
Axiomatic holonomy maps and generalized Yang-Mills moduli space

This Letter is a follow-up of Barrett, J. W.,Internat. J. Theoret. Phys. 30(9), (1991). Its main goal is to provide an alternative proof of that part of the reconstruction theorem which concerns the existence of a connection. A construction of a connection 1-form is presented. The formula expressing the local coefficients of the connection in terms of the holonomy map is obtained as an immediate consequence of that construction. Thus, the derived formula coincides with that used in Chan, H.-M., Scharbach, P., and Tsou, S. T.,Ann. Physics166, 396–421 (1986). The reconstruction and representation theorems form a generalization of the fact that the pointed configuration space of the classical Yang-Mills theory is equivalent to the set of all holonomy maps. The point of this generalization is that there is a one-to-one correspondence not only between the holonomy maps and the orbits in the space of connections, but also between all maps ΩM → G fulfilling some axioms and all possible equivalence classes ofP(M, G) bundles with connections, where the equivalence relation is defined by a bundle isomorphism in a natural way.
The Conjugacy Search Problem in Public Key Cryptography: Unnecessary and Insufficient

The conjugacy search problem in a group G is the problem of recovering an $$x \in G$$ from given $$g \in G$$ and h = xź1gx. This problem is in the core of several recently suggested public key exchange protocols, most notably the one due to Anshel, Anshel, and Goldfeld, and the one due to Ko, Lee et al. In this note, we make two observations that seem to have eluded most people's attention. The first observation is that solving the conjugacy search problem is not necessary for an adversary to get the common secret key in the Ko---Lee protocol. It is sufficient to solve an apparently easier problem of finding $$x, y \in G$$ such that h = ygx for given $$g, h \in G$$. Another observation is that solving the conjugacy search problem is not sufficient for an adversary to get the common secret key in the Anshel---Anshel---Goldfeld protocol.
The Multiple Continuum Components in the White-Light Flare of 16 January 2009 on the dM4.5e Star YZ CMi

The white light during M dwarf flares has long been known to exhibit the broadband shape of a T≈10 000 K blackbody, and the white light in solar-flares is thought to arise primarily from hydrogen recombination. Yet, a current lack of broad-wavelength coverage solar flare spectra in the optical/near-UV region prohibits a direct comparison of the continuum properties to determine if they are indeed so different. New spectroscopic observations of a secondary flare during the decay of a megaflare on the dM4.5e star YZ CMi have revealed multiple components in the white-light continuum of stellar flares, including both a blackbody-like spectrum and a hydrogen-recombination spectrum. One of the most surprising findings is that these two components are anti-correlated in their temporal evolution. We combine initial phenomenological modeling of the continuum components with spectra from radiative hydrodynamic models to show that continuum veiling causes the measured anti-correlation. This modeling allows us to use the components’ inferred properties to predict how a similar spatially resolved, multiple-component, white-light continuum might appear using analogies to several solar-flare phenomena. We also compare the properties of the optical stellar flare white light to Ellerman bombs on the Sun.
Characterization of Group 5 dubnium homologs on diglycolamide extraction chromatography resins from nitric and hydrofluoric acid matrices

A diglycolamide-based resin was characterized for Group 5 (Ta, Nb and pseudo-homolog Pa) separation from Group 4 (Hf and Zr) and tri-valent actinides (Am). The batch uptake of the radionuclides of interest were determined for HNO3/HF matrices and the results were used to develop a column separation method that could be used for element 105 (Db) purification chemistry. Tantalum is significantly retained by the TODGA resin, while Pa/Nb show little to no retention. The affinity for Ta decreases as a function of increased [HNO3], while Zr/Hf (and Am) affinities increase under the same conditions. Adsorption of Ta to polypropylene vials and column frits became a significant focus of this work following several observations made during the course of the column separation method development. All of the Group 5 elements were separated from Group 4 and Am while Ta may be completely isolated from Nb/Pa with the TODGA resin with improvements in column parameters: column height and bed volume.
Enhancement of optics-to-THz conversion efficiency by metallic slot waveguides

A metallic slot waveguide, with a dielectric strip embedded within, is investigated for the purpose of enhancing the optics-to-THz conversion efficiency using the difference-frequency generation (DFG) process. To describe the frequency conversion process in such lossy waveguides, a fully-vectorial coupled-mode theory is developed. Using the coupled-mode theory, we outline the basic theoretical requirements for efficient frequency conversion, which include the needs to achieve large coupling coefficients, phase matching, and low propagation loss for both the optical and THz waves. Following these requirements, a metallic waveguide is designed by considering the trade-off between modal confinement and propagation loss. Our numerical calculation shows that the conversion efficiency in these waveguide structures can be more than one order of magnitude larger than what has been achieved using dielectric waveguides. Based on the distinct impact of the slot width on the optical and THz modal dispersion, we propose a two-step method to realize the phase matching for general pump wavelengths.
An Experimental Investigation of Pull Contracts in Supply Chains

In this study, I investigate supply chain contracts in a setting where a supplier uses its inventory to directly satisfy a retailer's demand. These “pull” contracts have increased in popularity in practice but have not been studied experimentally. In a controlled laboratory setting, I evaluate a wholesale price contract and two coordinating contracts. The data suggest that the benefit of the two coordinating contracts over the wholesale price contract is less than the standard theory predicts, and that retailers, in the two coordinating contracts, exhibit a systematic bias of setting the coordinating parameter too low, and the wholesale price too high, relative to the normative benchmarks. In an effort to explain this deviation, I explore three behavioral models and find that loss aversion and reference dependence fit the data well. I empirically test this result in a follow-up experiment, which directly controls for loss aversion and reference dependence, and observe that retailers make significantly better decisions. Lastly, I administer a number of experiments which reduce the complexity of the problem, curtail the amount of risk, and increase the level of decision support, and find that none improve decisions relative to the treatment that controls for loss aversion and reference dependence.
The Interaction of Immigrant Culture and the Law: Focus on Parental Discretion under IDEIA of 2004

This article explores the potential impact traditional immigrant culture could have on the use of special education and related services for children with disabilities. Specifically, I focus on how traditional immigrant cultural attitudes towards disabilities may lead to an exercise of parental discretion to refuse special education and related services as allowed for under the Individuals with Disabilities Education Improvement Act of 2004 (IDEIA). My thesis is that traditional immigrant cultural attitudes towards disability healthcare will cause immigrant families to refuse the use of special education and related services for children with disabilities. To explore this research question, I administered questionnaires to (72) recent immigrants to the St. Louis, Missouri metropolitan area who came to the region from the Republic of Bosnian-Herzegovina. The results proved counter to the extant literature regarding traditional immigrant cultural attitudes towards disability healthcare. When controlling for...
Rhodium(III)-catalyzed oxidative carbonylation of benzamides with carbon monoxide.

An efficient strategy for the oxidative carbonylation of aromatic amidesvia C–H/N–H activation to form phthalimides using an Rh(III) catalyst has been developed. The reaction shows a preference for C–H bonds of electron-rich aromatic amides and tolerates a variety of functional groups.
Tip-Clearance Actuation With Magnetic Bearings for High-Speed Compressor Stall Control

Magnetic bearings are widely used as active suspension devices in rotating machinery, mainly for active vibration control purposes. The concept of active tip-clearance control suggests a new application of magnetic bearings as servo-actuators to stabilize rotating stall in axial compressors. This paper presents a first-of-a-kind feasibility study of an active stall control experiment with a magnetic bearing servo-actuator in the NASA Glenn high-speed single-stage compressor test facility. Together with CFD and experimental data a two-dimensional, incompressible compressor stability model was used in a stochastic estimation and control analysis to determine the required magnetic bearing performance for compressor stall control. The resulting requirements introduced new challenges to the magnetic bearing actuator design. A magnetic bearing servo-actuator was designed that fulfilled the performance specifications. Control laws were then developed to stabilize the compressor shaft. In a second control loop, a constant gain controller was implemented to stabilize rotating stall. A detailed closed loop simulation at 100 percent corrected design speed resulted in a 2.3 percent reduction of stalling mass flow, which is comparable to results obtained in the same compressor by Weigl et al. (1998. ASME J. Turbomach. 120, 625-636) using unsteady air injection. The design and simulation results presented here establish the viability of magnetic bearings for stall control in aeroengine high-speed compressors. Furthermore, the paper outlines a general design procedure to develop magnetic bearing servo-actuators for high-speed turbomachinery.
Iridium-Catalyzed Allylation of Chiral β-Stereogenic Alcohols: Bypassing Discrete Formation of Epimerizable Aldehydes

The cyclometalated π-allyliridium 3,4-dinitro-C,O-benzoate complex modified by (R)- or (S)-Cl,MeO-BIPHEP promotes the transfer hydrogenative coupling of allyl acetate to β-stereogenic alcohols with good to excellent levels of catalyst-directed diastereoselectivity to furnish homoallylic alcohols. Remote electronic effects of the C,O-benzoate of the catalyst play a critical role in suppressing epimerization of the transient α-stereogenic aldehyde.
Cost-saving properties of schedule coordination in a simple trunk-and-feeder transit system

The paper explores how the coordination of vehicle schedules in a public transit system affects generalized costs. We consider an idealized system that delivers its users to a common destination by requiring each to transfer from a feeder- to a trunk-line vehicle. Continuum models are used first to analyze cases in which the trunk-line vehicle schedule is given exogenously. We find that when feeder vehicles are dispatched in coordination with this exogenous trunk-line schedule, the reduction in user cost often outweighs the added cost to the feeder operation. In cases when the frequencies of trunk and feeder services can be established jointly, the models show that coordination can be Pareto improving, meaning that operator and user costs both diminish. Conditions that give rise to these cost savings are specified. Practical implications are discussed.
Colloidal particle motion as a diagnostic of DNA conformational transitions

Tethered particle motion is an experimental technique to monitor conformational changes in single molecules of DNA in real time, by observing the position fluctuations of a micrometer-size particle attached to the DNA. This article reviews some recent work on theoretical problems inherent in the interpretation of TPM experiments, both in equilibrium and dynamical aspects.
Electrostatic Potentials in Supernova Remnant Shocks

Recent advances in the understanding of the properties of supernova remnant shocks have been precipitated by the Chandra and XMM X-ray Observatories, and the HESS Atmospheric Cerenkov Telescope in the TeV band. A critical problem for this field is the understanding of the relative degree of dissipative heating/energization of electrons and ions in the shock layer. This impacts the interpretation of X-ray observations, and moreover influences the efficiency of injection into the acceleration process, which in turn feeds back into the thermal shock layer energetics and dynamics. This paper outlines the first stages of our exploration of the role of charge separation potentials in non-relativistic electron-ion shocks where the inertial gyro-scales are widely disparate, using results from a Monte Carlo simulation. Charge density spatial profiles were obtained in the linear regime, sampling the inertial scales for both ions and electrons, for different magnetic field obliquities. These were readily integrated to acquire electric field profiles in the absence of self-consistent, spatial readjustments between the electrons and the ions. It was found that while diffusion plays little role in modulating the linear field structure in highly oblique and perpendicular shocks, in quasi-parallel shocks, where charge separations induced by gyrations are small, and shock-layer electric fields are predominantly generated on diffusive scales.
ACCRETION OUTBURSTS IN CIRCUMPLANETARY DISKS

We describe a model for the long-term evolution of a circumplanetary disk that is fed mass from a circumstellar disk and contains regions of low turbulence (dead zones). We show that such disks can be subject to accretion-driven outbursts, analogous to outbursts previously modeled in the context of circumstellar disks to explain FU Ori phenomena. Circumplanetary disks around a proto-Jupiter can undergo outbursts for infall accretion rates onto the disks in the range , typical of accretion rates in the T Tauri phase. During outbursts, the accretion rate and disk luminosity increases by several orders of magnitude. Most of the planet mass growth during planetary gas accretion may occur via disk outbursts involving gas that is considerably hotter than predicted by steady state models. For low infall accretion rates that occur in late stages of disk accretion, disk outbursts are unlikely to occur, even if dead zones are present. Such conditions are favorable for the formation of icy satellites.
Better extractors for better codes

We present an explicit construction of codes that can be list decoded from a fraction (1-e) of errors in sub-exponential time and which have rate e/logO(1)(1/e). This comes close to the optimal rate of Ω(e), and is the first sub-exponential complexity construction to beat the rate of e2 achieved by Reed-Solomon or algebraic-geometric codes. Our construction is based on recent extractor constructions with very good seed length [17]. While the "standard" way of viewing extractors as codes (as in [16]) cannot beat the O(e2) rate barrier due to the 2 log (1/e) lower bound on seed length for extractors, we use such extractor codes as a component in a well-known expander-based construction scheme to get our result. The O(e2) rate barrier also arises if one argues about list decoding using the minimum distance (via the so-called Johnson bound) --- so this also gives the first explicit construction that "beats the Johnson bound" for list decoding from errors.The main message from our work is perhaps conceptual, namely that good strong extractors for low min-entropies will yield near-optimal list decodable codes. Given all the progress that has been made on extractors, we view this as an optimistic avenue to look for better list decodable codes, both by looking for better explicit extractor constructions, as well as by importing non-trivial techniques from the extractor world in reasoning about and constructing codes.
Synthesis of Anilines

1 Introduction 2 Uncatalyzed Reactions 3 Palladium-Catalyzed Methods 4 Mechanism of Palladium-Catalyzed Amination of Aryl Halides 5 Copper-Mediated Methods 6 Mechanism of Copper-Mediated/Catalyzed Reactions Keywords: aromatic amines; direct nucleophilic substitution; palladium-catalyzed methods; ligand aniline arylation; palladium-catalyzed arylation; functionalized aryl bromide reactions; aryl halide palladium-catalyzed amination mechanism; copper-mediated methods
From lightcone actions to maximally supersymmetric amplitudes

In this article actions for $ \mathcal{N} = 4 $ SYM and $ \mathcal{N} = 8 $ supergravity are formulated in terms of a chiral superfield, which contains only the physical degrees of freedom of either theory. In these new actions, which originate from the lightcone superspace, the super-gravity cubic vertex is the square of the gauge theory one (omitting the color structures). Amplitude calculations using the corresponding Feynman supergraph rules are tedious, but can be simplified by choosing a preferred superframe. Recursive calculations of all MHV amplitudes in $ \mathcal{N} = 4 $ SYM and the four-point $ \mathcal{N} = 8 $ supergravity amplitude are shown to agree with the known results and connections to the BCFW recursion relations are pointed out. Finally, the new actions are discussed in the context of the double-copy property relating $ \mathcal{N} = 4 $ SYM theory to $ \mathcal{N} = 8 $ supergravity.
Design Considerations for Large Detector Arrays on Submillimeter-wave Telescopes

The emerging technology of large (approximately 10,000 pixel) submillimeter-wave bolometer arrays presents a novel optical design problem -- how can such arrays be fed by diffraction- limited telescope optics where the primary mirror is less than 100,000 wavelengths in diameter? Standard Cassegrain designs for radiotelescope optics exhibit focal surface curvature so large that detectors cannot be placed more than 25 beam diameters from the central ray. The problem is worse for Ritchey-Chretien designs, because these minimize coma while increasing field curvature. Classical aberrations, including coma, are usually dominated by diffraction in submillimeter- wave single dish telescopes. The telescope designer must consider (1) diffraction, (2) aberration, (3) curvature of field, (4) cross-polarization, (5) internal reflections, (6) the effect of blockages, (7) means of beam chopping on- and off-source, (8) gravitational and thermal deformations of the primary mirror, (9) the physical mounting of large detector packages, and (10) the effect of gravity and (11) vibration on those detectors. Simultaneous optimization of these considerations in the case of large detector arrays leads to telescopes that differ considerably from standard radiotelescope designs. Offset optics provide flexibility for mounting detectors, while eliminating blockage and internal reflections. Aberrations and cross-polarization can be the same as on-axis designs having the same diameter and focal length. Trade-offs include the complication of primary mirror homology and an increase in overall cost. A dramatic increase in usable field of view can be achieved using shaped optics. Solutions having one to six mirrors will be discussed, including possible six-mirror design for the proposed South Pole 10 m telescope.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Mobilization, Repression, and Revolution: Grievances and Opportunities in Contentious Politics

I develop a framework to study the interactions between dissidents and the state that reconciles political-process and grievance-based theories of protests and provides insights into interpreting the conflicting empirical studies that sometimes support one theory and sometimes the other. I show that contrary to the theoretical predictions of the literature, the relationship between the magnitude of grievances (e.g., the level of income inequality or economic hardship) and the likelihood of repression can be nonmonotone, and given some assumptions, is U-shaped. That is, as the magnitude of grievances increases from low to high, the likelihood of repression first decreases and then increases. Indeed, the data suggest a nonmonotone, U-shaped relationship between the level of repression and income inequality. I also discuss the implications for the empirical studies of repression.
Enantioselective strategy to the spirocyclic core of Palau'amine and related bisguanidine marine alkaloids.

An enantioselective strategy to the spirocyclic core found in the oroidin-derived family of bisguanidine marine alkaloids has been devised, premised on a biosynthetic proposal. Herein, we describe the successful implementation of this strategy, which entails a Diels−Alder reaction and a chlorination/ring contraction sequence that delivers the fully functionalized spirocyclic core. In this initial report, an intermolecular chlorination delivers a cyclopentane that is epimeric at C17 relative to the palau'amines and epimeric at C11 relative to the axinellamines.
Personal finance: an alternative approach to teaching undergraduate finance

Abstract Effective teaching invites students into the discipline and helps them to see and make connections between the discipline's content and their lives. This paper identifies an alternative approach to effective teaching of undergraduate finance. Personal finance, as opposed to managerial finance, provides a more appropriate foundation on which to center the undergraduate finance curriculum. It better matches students' interests, personal experiences, and cognitive structures. This paper takes the position that personal finance should precede managerial finance as the introduction and start to the finance major in the undergraduate business curriculum.
A scheme to deal accurately and efficiently with complex angular masks in galaxy surveys

This paper presents a scheme to deal accurately and efficiently with complex angular masks, such as occur typically in galaxy surveys. An angular mask is taken to be an arbitrary union of arbitrarily weighted angular regions bounded by arbitrary numbers of edges. The restrictions on the mask are (i) that each edge must be part of some circle on the sphere (but not necessarily a great circle), and (ii) that the weight within each subregion of the mask must be constant. The scheme works by resolving a mask into disjoint polygons, convex angular regions bounded by arbitrary numbers of edges. The polygons may be regarded as the ‘pixels’ of a mask, with the feature that the pixels are allowed to take a rather general shape, rather than following some predefined regular pattern. Among other things, the scheme includes facilities to compute the spherical harmonics of the angular mask, and Data–Random and Random–Random angular integrals. A software package mangle that implements this scheme, along with complete software documentation, is available at http://casa.colorado.edu/~ajsh/mangle/.
Random motion with interfacial contact: Driven diffusion vis-à-vis mechanical activation

Rolling of a small sphere on a patterned support of an elastomer is governed by a non-linear friction. No motion occurs when the external field is weaker than the frictional resistance. However, with the intervention of an external noise, a viscous friction like behavior emerges; thus the sphere rolls with a uniform drift velocity that is proportional to the applied field. At a very low noise strength, the sphere exhibits a stick-slip behavior with motion occurring always along the bias. With the increase in the noise strength, the sphere exhibits a diffusive drift accompanied with forward and backward displacements. During this stage of driven diffusive motion, the ratio of the integrated probabilities of the negative-to-positive work fluctuations decreases monotonically with the time of observation, from which a temperature like intensive parameter can be estimated. This parameter conforms to Einstein’s ratio of diffusivity and mobility that increases almost linearly, even though the diffusivity increases super-linearly, with the strength of the noise. A new barrier crossing experiment is introduced that can be performed either with a hard (e.g. a steel ball) or with a soft (e.g. a water drop) sphere in contact with a periodically undulated substrate. The frequency of barrier crossing follows a transition state equation allowing a direct estimation of the effective temperature. These experiments as well as certain numerical simulations suggest that the effective temperature of a system controlled by a non-linear friction may not have a unique value.
Trace metal transport by marine microorganisms: implications of metal coordination kinetics

Marine microorganisms have transport systems capable of accumulating essential trace metals present at low oceanic concentrations—1 pM to 1 nM. In marine phytoplankton, Fe, Mn, Zn and Ni transport has been shown to involve complexation by membrane carriers. By analysing the kinetics of the transport process and accounting for the inherently slow coordination reactions of some of these metals, we predict optimum properties and minimum numbers of sites for the transport systems. Limits to trace metal uptake, and thereby to growth rates, may arise from finite space for these transport sites in the membrane, competition from other metals and the rate of diffusion to the cell. These types of nutrient limitation should exhibit different size dependencies and therefore be important in determining ecosystem structure. The concentrations of inorganically complexed species of nutrient metals remaining in the surface ocean appear to be correlated with predicted rates of metal complexation by trace metal transport sites, suggesting that kinetic liability controls the bioavailability of these metals and their rate of removal from the surface ocean.
Risk factors for adverse outcomes in spontaneous versus assisted conception twin pregnancies

Abstract Objective To evaluate risk factors for adverse outcomes in spontaneous vs. assisted conception twin pregnancies. Design Historical cohort study. Setting Four academic tertiary medical centers. Patient(s) Women with twin pregnancies, including 2,143 spontaneous and 424 assisted conception; 2,492 nonreduced and 75 reduced. Intervention(s) None (observational). Main outcome measure(s) Preeclampsia, preterm premature rupture of membranes, birth Result(s) Among nonreduced pregnancies, assisted conception was not significantly associated with any adverse outcomes; among nulliparas, the risk for preeclampsia was increased regardless of method of conception; among spontaneous conceptions, the risks for preterm premature rupture of membranes, low birth weight, very low birth weight, and slowed midgestation fetal growth were increased. Among all pregnancies, fetal reduction increased risks for birth Conclusion(s) These findings indicate that in twin pregnancies, assisted conception is not a risk factor for adverse outcomes, but rather specific factors that are more common among these pregnancies, such as nulliparity and fetal reduction, increase risks.
Effects of Nonequilibrium Ablation Chemistry on Viking Radio Blackout

The length of the entry blackout period during descent of the Viking Lander into the Mars atmosphere is predicted from calculated profiles of electron density in the shock layer over the aeroshell. Nonequilibrium chemistry plays a key role in the calculation, both in the inviscid flow and in the boundary layer. This is especially true in the boundary layer contaminated with ablation material, for which nonequilibrium chemistry predicts electron densities two decades lower than the same case calculated with equilibrium chemistry.
On certain computations of Pisot numbers

This paper presents two algorithms on certain computations about Pisot numbers. Firstly, we develop an algorithm that finds a Pisot number @a such that Q[@a]=F given a real Galois extension F of Q by its integral basis. This algorithm is based on the lattice reduction, and it runs in time polynomial in the size of the integral basis. Next, we show that for a fixed Pisot number @a, one can compute [@a^n](modm) in time polynomial in (log(mn))^O^(^1^), where m and n are positive integers.