cssi/SciSciGPT-SciSciNet huggingface dataset:
The hyperplane is the only stable, smooth solution to the Isoperimetric Problem in Gaussian space

We study stable, two-sided, smooth, properly immersed solutions to the Gaussian Isoperimetric Problem. That is, we study hyper-surfaces \(\Sigma ^n \subset {{\mathbb {R}}}^{n+1}\) that are second order stable critical points of minimizing \({{\mathcal {A}}}_\mu (\Sigma ) = \int _\Sigma e^{-|x|^2/4} \, d {{\mathcal {A}}}\) for compact variations that preserve weighted volume. Such variations are represented by \(u \in C^\infty _0(\Sigma )\) such that \(\int _\Sigma e^{-|x|^2/4} u \, d {{\mathcal {A}}}= 0\). We show that such \(\Sigma \) satisfy the curvature condition \(H = \langle x, N \rangle /2 + C\) where \(C\) is a constant. We also derive the Jacobi operator \(L\) for the second variation of such \(\Sigma \). Our first main result is that for non-planar \(\Sigma \), bounds on the index of \(L\), acting on volume preserving variations, gives us that \(\Sigma \) splits off a linear space. A corollary of this result is that hyper-planes are the only stable smooth, complete, properly immersed solutions to the Gaussian Isoperimetric Problem, and that there are no hypersurfaces of index one. Finally, we show that for the case of \(\Sigma ^2 \subset {{\mathbb {R}}}^3\), there is a gradient decay estimate for fixed bound \(|C| \le M\) (\(C\) is from the curvature condition) and \(\Sigma \) obeying an appropriate \({{\mathcal {A}}}_\mu \) condition. This shows that for fixed \(C\), in the limit as \(R \rightarrow \infty \), stable \((\Sigma , \partial \Sigma ) \subset (B_{2R}(0), \partial B_{2R}(0))\) with good volume growth bounds approach hyper-planes.
Saturistors and Low Starting Current Induction Motors

By locating a hard magnetic material, such as Alnico, in the leakage flux paths of the secondary circuits of an induction motor, a remarkably high locked-rotor torque per ampere can be obtained, without sacrifice of full-load speed. This paper presents test data for both wound-rotor and squirrel-cage motors, using this Saturistor principle. The motors so made are series hysteresis (induction) motors, with completely different characteristics from the familiar shunt-type hysteresis (synchronous) motor.
Synthesis and high-temperature stability of Ti3SiC2

Abstract Titanium silicon carbide (Ti3SiC2) was synthesized by reactive sintering of elemental reactants. By using an off-stoichiometric ratio (1.2 moles of silicon), Ti3SiC2 with a purity of better than 98 vol.% was synthesized. The synthesized materials were annealed at 1600°C and 1800°C for up to 10 h to verify its chemical stability at high temperatures. The ternary compound was found to be stable at temperatures as high as 1800°C under an argon atmosphere. Dense compacts of Ti3SiC2 were obtained by hot pressing of reactively sintered compacts. The oxidation behavior of the ternary compound was investigated in air at 1000°C and found to be paralinear.
Trends in engineering education

It is argued that to report accurately on trends in engineering education, one must first explain that higher education, in general, is in a state of crisis. Problems in individual departments must be viewed in the context of being a small part of the beleagured university as a whole.
Kinematic Transformation Matrices for 3D Surface Contact Joints

A generalized procedure is presented for the development of a pair matrix that describes kinematic joints formed by contact between three-dimensional surfaces. The pair matrix is useful in the matrix-based kinematic analysis procedure put forth by Sheth and Uicker (1971) previously. Any two surfaces may make up the joint as long as the surfaces can be described parametrically, and contact takes place at one point. The corresponding pair matrix is a function of five pair variables.
Quark mass matrices from a softly broken U(1) symmetry

Abstract Assigning U(1) charges to the quarks of the standard model, and allowing one extra scalar doublet with m 2 >0, the correct pattern of the up and down quark mass matrices is obtained, together with their charged-current mixing matrix.
Wavelet-Based Estimation for Seasonal Long-Memory Processes

We introduce the multiscale analysis of seasonal persistent processes, that is, time series models with a singularity in their spectral density function at one or more frequencies in [0,1/2]. The discrete wavelet packet transform (DWPT) and a nondecimated version of it known as the maximal overlap DWPT (MODWPT) are introduced as alternative methods to Fourier-based techniques for analyzing time series that exhibit seasonal long memory. The approximate log-linear relationship between the wavelet packet variance and frequency is used to produce a least squares estimator of the fractional difference parameter. Approximate maximum likelihood estimation is performed by replacing the variance/covariance matrix with a diagonalized matrix based on the DWPT. Simulations are performed to compare the wavelet-based techniques with the spectral estimate-based techniques for both least squares and maximum likelihood procedures. An application of this methodology to atmospheric and economic time series is used for demon...
A framework for evaluating DTN mobility models

The field of delay tolerant networking is rich with protocols that exploit node mobility to overcome unpredictable or otherwise bad connectivity. The performance of many of these protocols is highly sensitive to the underlying mobility model which determines the nodes' movements, and the characteristics of these mobility models are not often studied or compared. With few exceptions, authors test their ideas using mobility models implemented on simulators written for the specific purpose of testing their protocols. We argue that it is better to unify these simulations to one highly capable simulator. We develop a suite of mobility models in OMNeT++ that specifically target delay tolerant networks. We also present a series of metrics that can be used to reason about mobility models independent of which communication protocols and data traffic patterns are in use. These metrics can be used to compare existing mobility models with future ones and also to provide insight into which characteristics of the mobility models affect which aspects of protocol performance. We implement a tool that derives these metrics from OMNeT++ simulations and implement several popular delay tolerant mobility models. Finally, we present the results of our analysis.
Lebowitz inequalities for Ashkin-Teller systems

Abstract We consider the Ashkin–Teller model with negative four-spin coupling but still in the region where the ground state is ferromagnetic. We establish the standard Lebowitz inequality as well as the extension that is necessary to prove a divergent susceptibility.
Seifert surfaces distinguished by sutured Floer homology but not its Euler characteristic

In this paper we find a family of knots with trivial Alexander polynomial, and construct two non-isotopic Seifert surfaces for each member in our family. In order to distinguish the surfaces we study the sutured Floer homology invariants of the sutured manifolds obtained by cutting the knot complements along the Seifert surfaces. Our examples provide the first use of sutured Floer homology, and not merely its Euler characteristic (a classical torsion), to distinguish Seifert surfaces. Our technique uses a version of Floer homology, called “longitude Floer homology” in a way that enables us to bypass the computations related to the SFH of the complement of a Seifert surface.
Voyager—Uranus at our doorstep

Following the encounter of Voyager 2 with Saturn and the subsequent approach, in January 1986, to the planet Uranus, the NASA Deep Space Network (DSN) undertook a reshaping of Voyager's end-to-end data system to provide communication to earth with a sufficient number of images for Uranus characterization. In-flight evolution of the spacecraft and ground system is described, with particular attention given to the aspects of target motion compensation, line enhancement, arraying, and encoding data streams. Solutions to the on-board problems encountered during the flight are presented. Voyager and its principal elements, an actuator for the scan platform, and the coding diagram are among the illustrations included.
Spatiotemporal Structure of Wind Farm-atmospheric Boundary Layer Interactions☆

Observations and modelling studies show that wind farms can alter their local microclimate. This study examines the effect of real-world wind farms on land surface temperatures in West Central Texas using the Weather Research and Forecasting model under realistic boundary conditions. Three wind turbine parameterizations, including two developed in this study, are used for model sensitivity experiments. The simulated effects of wind farms on temperatures match the spatial patterns observed in satellite data but are weaker in magnitude. The magnitudes of the temperature changes depend on the power coefficients used in the parameterizations.
An Explanation for Neptune's Ring Arcs

The Voyager mission revealed a complex system of rings and ring arcs around Neptune and uncovered six new satellites, four of which occupy orbits well inside the ring region. Analysis of Voyager data shows that a radial distortion with an amplitude of approximately 30 kilometers is traveling through the ring arcs, a perturbation attributable to the nearby satellite Galatea. Moreover, the arcs appear to be azimuthally confined by a resonant interaction with the same satellite, yielding a maximum spread in ring particle semimajor axes of 0.6 kilometer and a spread in forced eccentricities large enough to explain the arcs' 15-kilometer radial widths. Additional ring arcs discovered in the course of this study give further support to this model.
Minimum wage effects on hours, employment, and number of firms: The iowa case

V. Conclusions Our results show that minimum wages reduce employment opportunities for workers. Like the early studies, our county-level (more aggregate) estimates imply fairly modest impacts with elasticities of approximately -0.1. However, our firm-level estimates for subminimum workers imply much more elastic responses. In particular, hours elasticities are in the elastic range.
Growth, trade and uneven development

Theories of growth and international trade are reviewed critically from the perspective of understanding persistent inter-country and inter-regional income inequality. Three separate literatures are considered for the insights they offer about international disparity: Classical political economy, the North-South trade models, and the 'new' growth and trade theories that incorporate increasing returns and/or product differentiation. Classical antecedents of the more recent theories are identified, and contrasts are drawn between structuralist and neoclassical approaches to explaining the income gap between rich and poor nations.
Discretely Actuated Manipulator Workspace Generation by Closed Form Convolution

We determine workspaces of discretely actuated manipulators using convolution of real-valued functions on the Special Euclidean Group. Each workspace is described in terms of a density function that provides the number of reachable frames inside any unit volume of the workspace. A manipulator consisting of n discrete actuators each with K states can reach Kn frames in space. Given this exponential growth, brute force representation of discrete manipulator workspaces is not feasible in the highly actuated case. However, if the manipulator is of macroscopically-serial architecture, the workspace can be generated by the following procedure: (1) partition the manipulator into B kinematically independent segments; (2) approximate the workspace of each segment as a continuous density function on a compact subset of the Special Euclidean Group; (3) approximate the whole workspace as a B-fold convolution of these densities. We represent density functions as finite Hermite-Fourier Series and show for the planar case how the B-fold convolution can be performed in closed form. If all segments are identical only O(log B) convolutions are necessary.
Stereochemical Aspects of Acid‐Catalyzed Cyclopropane Ring‐Opening Reactions. A Stereospecific Pathway to Crinosterol and Brassicasterol

It is shown that the acid-catalyzed ring-opening of the two diastereoisomeric 23:24-methylenecholesterols 3 and 5 on treatment with gaseous HCl in acetic acid leads stereospecifically to the naturally occurring crinosterol (4) and brassicasterol (6), respectively (Scheme 1). This isomerization can be viewed as a biomimetic model of an in vivo methylation process of the type already known in plant sterol metabolism (cf. cycloeucalenol obtusifoliol, 1 2). The synthetic application of this method provides a convenient labelling of sterol side chains for tracer experiments. The mechanistic features of the reaction with respect to its particular stereospecificity are discussed.
A buffered two-node packet radio network with product form solution

A packet radio network with two nodes, both of which access a single radio channel using the slotted ALOHA protocol, is discussed. This model results in a network of two interfering queues. Networks of interfering nodes normally do not have partial balance and thus seldom have product-form solution (PFSs). However, when certain assumptions are made on the network parameters, PFS-controls can be found that yield a PFS for the interfering two-node network. Three such cases are described. In the first two cases, PFS controls are found that control the new packet arrival rate. When operating under these PFS controls, the two-mode network has a simple, closed-form solution of the equilibrium probabilities, the expected throughput, and the expected packet delay. The throughput-delay performance closely approximates that of an exact two-node packet radio model. In the third case, a PFS control is found on one node's transmission probabilities. When operating under this PFS control, the transmission probabilities approach asymptotic values as the packet backlog increases. The network tends to adjust its transmission probabilities to reduce large unequal packet backlogs. >
A Band Spectral Analysis of Exports and Economic Growth in the United States

This paper examines the role of exports in aggregate economic growth in the United States using band spectral regression. The findings reveal a predictable relationship between long-run frequency components of real export growth and real GDP growth over the post-Bretton Woods period of flexible exchange rates. The study fails to uncover a significant relationship between long-run frequency components of the terms of trade and real output. Overall, the findings support the export-led growth hypothesis, and dismiss long-run movements in the terms of trade as an important determinant of real output growth.
Learning in mis-specified models and the possibility of cycles

Abstract I study the problem of a monopolist maximizing a sum of discounted profits facing a linear demand curve whose slope and intercept are unknown. I show that if the monopolist has a mis-specified model, i.e., if the true slope and intercept lie outside of the support of the monopolist's prior beliefs, then actions and beliefs may cycle on every sample path. This behavior is shown to be robust to perturbations in the prior, true parameter, and actions. Such behavior is not possible if the agent's model is correctly specified; instead actions and beliefs necessarily converge.
Generation and alkylation of 2-boryl allylic sulfone anions

The deprotonation and electrophilic trapping of an allylic sulfone substituted at the 2 position by a pinacol boronate results in the formation of the corresponding alkylation products. The ability of the boronate ester to tolerate the sulfonyl carbanion suggests a broader application of the methodology to prepare a wide range of functionalized boronates.
Causality based generation of directed test cases

Simulation is considered to be the irreplaceable part of design verification. However, the efficiency of this method depends greatly on the test cases used. Random test cases can be generated quickly but have poor coverage. Directed test cases on the other hand require time and manual effort. This paper presents a method for generating directed test cases automatically by making use of signal relationships in the specification. An algorithm is presented that was applied to the GL85 microprocessor, a clone of Intel's 8085. The results are compared with other methods to see the gain with the proposed method.
Palladium-Catalyzed Coupling of 3-Indolyl Triflate. Syntheses of 3-Vinyl and 3-Alkynylindoles

Abstract Palladium-catalyzed coupling of 1-(phenylsulfonyl)indol-3-yl trifluoromethanesulfonate (triflate) (1) with terminal alkenes and alkynes gives 3-vinyl (2) and 3-alkynylindoles in 45—93% yields. An attempt to generate 2, 3-indolyne 22 from 2-trimethylsilyl-3-indolyl triflate 20 gives indigo (23).
Using expert systems to manage distributed computer systems

The problems encountered in decentralized control are identified, and an informal description is given of how expert-systems techniques can help in addressing some of them. A model of a distributed system is given, the characteristics of a distributed intelligent resource manager are discussed, and the architecture of an expert manager currently being built is described. >
Response of the summertime ground-level ozone trend in the Chicago area to emission controls and temperature changes, 2005–2013

Abstract Despite strenuous efforts to reduce the emissions of ozone precursors such as nitrogen oxides (NO x ), concentrations of ground-level ozone (O 3 ) still often exceed the National Ambient Air Quality Standard in U.S. cities in summertime, including Chicago. Furthermore, studies have projected a future increase in O 3 formation due to global climate change. This study examines the response of summertime O 3 to emission controls and temperature change in the Chicago area from 2005 to 2013 by employing observations of O 3 , O 3 precursors, and meteorological variables. We find that meteorology explains about 53% of the O 3 variance in Chicago. O 3 mixing ratios over Chicago are found to show no clear decline over the 2005–2013 period. The summertime ground-level O 3 trend consists of a decrease of 0.08 ppb/year between 2005 and 2009 and an increase of 1.49 ppb/year between 2009 and 2013. Emissions of NO x and concentrations of NO 2 have been decreasing steadily from 2005 to 2013 in the Chicago area. Concentrations of volatile organic compounds (VOCs) in Chicago, however, have more than doubled since 2009, even though emission inventories suggest that VOC emissions have decreased. We believe that O 3 production in Chicago became more sensitive to VOCs starting in 2008/2009 and may have switched from being NO x -limited to VOC-limited. The warmer climate since 2008 has also contributed to the increasing ozone trend in the Chicago area. Increased attention should be paid to improving the quantification of VOC sources, enhancing the monitoring of reactive VOC concentrations, and designing VOC mitigation measures.
A flexible platform for hardware-aware network experiments and a case study on wireless network coding

In this paper, we present the design and implementation of a general, flexible, hardware-aware network platform that takes hardware processing behavior into consideration to accurately evaluate network performance. The platform adopts a network-hardware co-simulation approach in which the NS-2 network simulator supervises the network-wide traffic flow and the SystemC hardware simulator simulates the underlying hard-ware processing in network nodes. In addition, as a case study, we implemented wireless all-to-all broadcasting with network coding on the platform. We analyze the hardware processing behavior during the algorithm execution and evaluate the overall performance of the algorithm. Our experimental results demonstrate that hardware processing can have a significant impact on the algorithm performance and hence should be taken into consideration in the algorithm design. We expect that this hardware-aware platform will become a very useful tool for more accurate network simulations and more efficient design space exploration of processing-intensive applications.
Design, synthesis and biological evaluation of carbohydrate-based mimetics of cRGDFV

Abstract The design, synthesis and preliminary biological evaluation of carbohydrate-based non-peptide mimetics of the potent peptidic antagonist of αvβ3 and αvβ5, pentapeptide cRGDFV (1) is presented. The design was based on the NMR-determined structure of 1.
Online Combustor Stability Margin Assessment Using Dynamic Pressure Data

This paper describes a strategy for determining a combustor's dynamic stability margin. Currently, when turbines are being commissioned or simply going through day to day operation, the operator does not know how the stability of the system is affected by changes to fuel splits or operating conditions unless, of course, pressure oscillations are actually present. We have developed a methodology, for ascertaining the stability margin from dynamic pressure data that does not require external forcing and that works even when pressure oscillations have very low amplitudes. This method consists of signal processing and analysis that determines a real-time measure of combustor damping. When the calculated damping is positive, the combustor is stable. As the damping goes to zero, the combustor approaches its stability boundary. Changes in the stability margin of each of the combustor's stable modes due to tuning, aging, or environmental changes can then be monitored through an on-line analysis of the pressure signal. This paper outlines the basic approach used to quantify acoustic damping and demonstrates the technique on combustor test data.
Transition to chaos in discrete nonlinear Schrödinger equation with long-range interaction

Discrete nonlinear Schrodinger (DNLS) equation describes a chain of oscillators with nearest-neighbor interactions and a specific nonlinear term. We consider its modification with long-range interaction through a potential proportional to 1/l1+α with fractional α<2 and l as a distance between oscillators. This model is called αDNLS. It exhibits competition between the nonlinearity and a level of correlation between interacting far-distanced oscillators, that is defined by the value of α. We consider transition to chaos in this system as a function of α and nonlinearity. It is shown that decreasing of α with respect to nonlinearity stabilize the system. Connection of the model to the fractional generalization of the NLS (called FNLS) in the long-wave approximation is also discussed and some of the results obtained for αDNLS can be correspondingly extended to the FNLS.
Ground-state entropy of the Potts antiferromagnet on cyclic strip graphs

We present exact calculations of the zero-temperature partition function (chromatic polynomial) and the (exponent of the) ground-state entropy S0 for the q-state Potts antiferromagnet on families of cyclic and twisted cyclic (Mobius) strip graphs composed of p-sided polygons. Our results suggest a general rule concerning the maximal region in the complex q plane to which one can analytically continue from the physical interval where S0 > 0. The chromatic zeros and their accumulation set exhibit the rather unusual property of including support for Re(q) < 0 and provide further evidence for a relevant conjecture.
Optimal support structures for chopping mirrors

The merits of a tangential spider vane support as opposed to a traditional radial vane support for telescope secondary mirrors are examined. Considerable interest in tangential spider design has been shown in recent large telescope projects. This configuration is used to limit vibration during the operation of the chopping secondary by improving the torsional stiffness.
Electron-deficient bonding in rhomboid rings.

The bonding environment of boron is usually thought about in terms of localized 2c−2e/3c−2e bonding (as in diborane) or completely delocalized polyhedral bonding (as in B12H122-). Recently, a number of boron compounds having a rhomboidal B4 framework have been synthesized; these show an amazing variation in their skeletal electron count, one that cannot be interpreted in familiar ways. In this report, we systematically explore the origin of the range of electron counts in these compounds. We find that four skeletal MOs are primarily responsible for keeping the B4 skeleton together. As a subunit in a macropolyhedral environment, termed rhombo-B4, such an arrangement of B atoms deviates from Wade's rule by three electron pairs (if treated as a distorted arachno system derived from B6H62-). Aided by this analysis, we examine the nature of bonding in Na3B20, where the rhombo-B4 unit forms linear chains fusing closo-B7 units. Theory suggests that this structure requires one more electron per formula unit for o...
High-Resolution CO Observations of Young Low-Mass Stars

We have observed CO emission near very young low mass stars using the Owens Valley Millimeter Interferometer. The data consist of a snapshot visibility survey of 25 IRAS/NH3 cores and full synthesis maps of two cores, L1262 and L1681B. The two sources show spatially compact (radius ≤ 1017 cm) low velocity outflows. Extrapolating from the snapshot survey, at least 64% and up to 100% of the sources have outflows. The momentum flux in the compact outflows is comparable to that powering larger scale low luminosity outflows. The core L1681B contains an unresolved source with velocity extent and emission asymmetries which are consistent with gravitational infall.
Stable transport of assemblies: pushing stacked parts

This work presents a method to determine stable pushing motions for a planar stack of polygonal parts. The approach consists of solving a series of subproblems where each part in the stack is pushing the parts ahead of it. The solutions to these subproblem an sets of stable motions, and their intersection is the set of stable motions for the entire stack. The motion of multiple parts depends on the exact locations of the centers of mass and the relative masses of the parts. If either or both of these is unknown, it is still possible to calculate a conservative set of motions guaranteed to be stable by using a center of mass uncertainty region. Local-local controllability is also analyzed for single parts and stocks of parts with uncertain centers of mass. Once parts have been brought together in an automated assembly sequence, they typically must be repositioned to complete fastening or welding operations. This can be done with powerful robots capable of grasping and carrying the assembly and may involve a unique fixture to maintain the assembly during transport. A cheaper and more flexible alternative is to use a less powerful robot that can push the assembly along a horizontal surface without the aid of fixtures. This work presents a graphical method that produces conservative bounds on the pushing motions that guarantee the stability of a linear assembly (i.e., a stock of parts) during the push. The main application is in motion planning for assembly sequencing but the results could also he useful, for example, for mobile robots pushing multiple boxes in a warehouse. The method can be made robust to uncertainty in The mass properties of the parts, such as boxes with unknown contents. It is limited to linear stacks of parts where each part pushes no more than one other part In future work, we plan to devise a method to compute stable pushing motions for arbitrary assemblies of parts.
Estimation of models with grouped and ungrouped data by means of "2SLS"

Abstract This paper deals with a special case of estimation with grouped data, where the dependent variable is only available for groups, whereas the endogenous regressor(s) is available at the individual level. By estimating the first stage using the available individual data, and then estimating the second stage at the aggregate level, it might be possible to gain efficiency relative to the OLS and 2SLS estimators that use only grouped data. We term this the mixed-2SLS estimator (M2SLS). The M2SLS estimator is consistent and asymptotically normal. We also provide a test of efficiency of M2SLS relative to OLS and “2SLS” estimators.
The Distance to the Galactic Center

The Optical Gravitational Lensing Experiment (OGLE) data on high-amplitude d Scuti stars (HADS) and RR Lyrae stars have been analyzed to determine the distance to the Galactic bulge. Individual color excesses and V absorption for each individual variable star have been computed, which lead to accurate magnitudes. The period-luminosity relation of the HADS is utilized to calculate distance SV 0 T moduli. We Ðnd that the metal-strong HADS are concentrated strongly to the bulge. The best distance modulus to the bulge from the HADS data is 14.49 ^ 0.06 mag. The dependence of on period for the M v bulge RR Lyrae stars can be found from the reddening-free magnitude The zero point of the V V~I. M v Elog P relation is set with the horizontal branches of Oosterho† type I globular clusters. mag (long- M v + 0.44 distance scale) in the log P interval (0.29 to (0.22 as inferred by main-sequence Ðtting of the clusters to local subdwarfs and utilizing short-period HADS in the clusters. The best distance modulus to the bulge from the RR Lyrae (ab) stars is 14.45 mag, which compares favorably with the distance modulus of 14.49 mag found from the HADS. We adopt the mean value 14.47 ^ 0.08 mag for the bulge distance modulus. A small additive correction leads to 7.9 ^ 0.3 kpc as the best distance to the Galactic center.
Fullerenes synthesis in combustion

Abstract The early suggestion in fullerenes research that fullerenes might be produced in flames was soon supported by the observation of polyhedral carbon ions in flames and in 1991 was confirmed by the recovery and identification of fullerenes C60 and C70 from benzene/oxygen flames. Recent research has determined the effects of pressure, carbon/oxygen ratio, temperature and the type and concentration of diluent gas, on the yields of C60 and C70 in subatmospheric pressure premixed laminar flames of benzene and oxygen. Similar flames but with acetylene as fuel have also been found to produce fullerenes, but in smaller yields than with benzene fuel. The largest observed yields of C60 + C70 from benzene/oxygen flames are substantial, being 20% of the soot produced and 0.5% of the carbon fed. The largest rate of production of C60 + C70 was observed at a pressure of 69 Torr, a C/O ratio of 0.989 and a dilution of 25% helium. Several striking differences between fullerenes formation in flames as compared to the widely used graphite vaporization method include, in the case of flames, an ability to vary the C70/C60 ratio from 0.26 to 8.8 (cf., 0.02 to 0.18 for graphite vaporization) by adjustment of flame conditions and production of several isomers each of fullerenes C 60, C70, C60O and C70O. Many of the apparent isomers are thermally metastable, one C60 converting to the most stable form with a half-life of 1h at 111°C. The structures of the apparent C60 and C70 isomers necessarily must include abutting five-membered rings, previously assumed to be disallowed because of their high strain energy. The chemistry of fullerenes formation in flames is in some ways similar to that of soot formation, but important differences are seen and assumed to reflect the effects of the curved, strained structures of fullerenes and their precursors.
Three-Pulse Photon Echo Peak Shift Spectroscopy in a Dense Potassium Vapor

The three-pulse photon echo technique has provided significant insight into ultrafast dynamics in a variety of condensed phase systems1. Clear signatures of non-Markovian dynamics in a dense potassium vapor2 provide the opportunity to gain further insight into the correlation function of frequency fluctuations both experimentally and theoretically. Here, experimental three-pulse photon echo peak shifts are compared to calculated peak shifts that include the long-range resonant interactions in a dense atomic vapor within an exciton formalism3. A slow exponential decay in the peak shifts is attributed to long-range resonant interactions.
How Much Is too Much? The Influence of Preschool Centers on Children's Social and Cognitive Development.

Abstract This paper examines the effects of different child-care arrangements on children's cognitive and social proficiencies at the start of kindergarten. Using data from the Early Childhood Longitudinal Study, we identify effects using OLS, matching and instrumental variables estimates. Overall, center-based care raises reading and math scores, but has a negative effect for socio-behavioral measures. However, for English-proficient Hispanic children, the academic gains are considerably higher and the socio-behavioral effects are neutral. The duration of center-based care matters: the greatest academic benefit is found for those children who start at ages 2–3 rather than at younger or older ages; negative behavioral effects are greater the younger the start age. These patterns are found across the distributions of family income. The intensity of center-based care also matters: more hours per day lead to greater academic benefits, but increased behavioral consequences. However, these intensity effects depend on family income and race.
Treatment effect bounds: An application to Swan–Ganz catheterization ☆

Abstract We reanalyze data from the observational study by Connors et al. (1996) on the impact of Swan–Ganz catheterization on mortality outcomes. The study by Connors et al. (1996) assumes that there are no unobserved differences between patients who are catheterized and patients who are not catheterized and finds that catheterization increases patient mortality. We instead allow for such differences between patients by implementing both the instrumental variable bounds of Manski (1990) , which only exploits an instrumental variable, and the bounds of Shaikh and Vytlacil (2011) , which exploit mild nonparametric, structural assumptions in addition to an instrumental variable. We propose and justify the use of indicators of weekday admission as an instrument for catheterization in this context. We find that in our application, the Manski (1990) bounds do not indicate whether catheterization increases or decreases mortality, where as the Shaikh and Vytlacil (2011) bounds reveal that at least for some diagnoses, Swan–Ganz catheterization reduces mortality at 7 days after catheterization. We show that the bounds of Shaikh and Vytlacil (2011) remain valid under even weaker assumptions than those described in Shaikh and Vytlacil (2011) . We also extend the analysis to exploit a further nonparametric, structural assumption–that doctors catheterize individuals with systematically worse latent health–and find that this assumption further narrows these bounds and strengthens our conclusions. In our analysis, we construct confidence regions using the methodology developed in Romano and Shaikh (2008) . We show in particular that the confidence regions are uniformly consistent in level over a large class of possible distributions for the observed data that include distributions where the instrument is arbitrarily “weak”.
Effects of random localizing events on matter waves: formalism and examples

A formalism is introduced to describe a number of physical processes that may break down the coherence of a matter wave over a characteristic length scale l. In a second-quantized description, an appropriate master equation for a set of bosonic 'modes' (such as atoms in a lattice, in a tight-binding approximation) is derived. Two kinds of 'localizing processes' are discussed in some detail and shown to lead to master equations of this general form: spontaneous emission, and modulation by external random potentials. Some of the dynamical consequences of these processes are considered: in particular, it is shown that they generically lead to a damping of the motion of the matter-wave currents, and may also cause a 'flattening' of the density distribution of a trapped condensate at rest.
Atmospheric consequences of cosmic‐ray variability in the extragalactic shock model

[1] It has been suggested that galactic shock asymmetry induced by our galaxy's infall toward the Virgo Cluster may be a source of periodicity in cosmic-ray exposure as the solar system oscillates normally to the galactic plane, thereby inducing an observed terrestrial periodicity in biodiversity. There are a number of plausible mechanisms by which cosmic rays might affect terrestrial biodiversity. Here we investigate one of these mechanisms, the consequent ionization and dissociation in the atmosphere, resulting in changes in atmospheric chemistry, which culminate in the depletion of ozone and a resulting increase in the dangerous solar UVB flux on the ground. We estimate the enhancement of cosmic-ray intensity for a range of reasonable parameters of the galactic wind and galactic magnetic field, and use these to compute steady-state atmospheric effects. At the lower end of this range, we find that the effects are far too small to be of serious consequence. At the upper end of this range, the level of ozone depletion approaches that currently experienced due to anthropogenic effects such as accumulated chlorofluorocarbons, i.e., ∼2.1% global average loss of ozone column density. We discuss some of the possible effects. While much smaller intensity than the atmospheric effects of a nearby galactic gamma-ray burst, the duration of the effects would be about 106 times greater. Current ozone depletion is a documented stress on the biosphere; it is not clear whether its consequences would be severe if of extended duration. We conclude that, for estimates at the upper end of the reasonable range of the cosmic-ray variability over geologic time, the mechanism of atmospheric ozone depletion may provide a small additional stress, enhancing the impact of other events. However, in order to account for large fluctuations in biodiversity correlated with cosmic-ray flux, other mechanisms should be investigated.
Electronic mechanism for the coexistence of ferroelectricity and ferromagnetism

The interplay between order parameters of different na-ture opens the door for designing new multifunctional de-vices whose properties can be manipulated with more thanone physical ﬁeld. For instance, the spin and orbital elec-tronic degrees of freedom can order individually or simulta-neously to produce different phases. In particular, orbital or-dering can produce symmetry-breaking states like orbitalmagnetism, ferroelectricity FE , quadrupolar electric ormagnetic ordering, and other multipolar orderings. The mag-netoelectric multiferroics, such as
The Uses of Ridicule: Humour, ‘Infrapolitics’ and Civil Society in Nigeria

As post-military ‘democratic’ regimes across Africa perpetuate norms and practices that were characteristic of the previous openly authoritarian era, humour and ridicule have emerged as a means through which ordinary people attempt to deconstruct and construct meaning out of a reality that is decidedly surreal. In Nigeria jokes serve a double function as a tool for subordinate classes to deride the state (including its agents) and themselves. Jokes are therefore a means through which an emergent civil society, ‘behaving badly’, subverts, deconstructs, and engages with the state. Yet, for all its significance as a form of agency, humour has been neglected in the civil society literature, partly because of the mentality which frames civil society in terms of organizations (humour is not organized), and partly because of its almost exclusive attention to the ‘civil’ attributes of civil society (humour is, inter alia, rude). This article argues for incorporating humour into the civil society discourse, and suggests that doing so will enrich civil society analysis by focusing on both the constructions of sociality and their associated politics, and the hidden spaces in which most of visible political action originates.
Improvements in risk factor control among persons with diabetes in the United States: Evidence and implications for remaining life expectancy

Abstract Aims To examine whether A1c, blood pressure, and cholesterol values changed for U.S. adults with diagnosed diabetes between 1988–1994 and 2005–2006. We then project the impact of these changes on life expectancy and diabetes-related complications. Methods We estimated changes in hemoglobin A1c, blood pressure, and total cholesterol between 1988–1994 and 2005–2006 using regression analysis and data from the National Health and Nutrition Examination Survey. We projected the potential effects on life expectancy and complications using the CDC-RTI Diabetes Cost-Effectiveness Model. Results A1c fell by 0.68 percentage points (P = 0.001) among U.S. adults with diagnosed diabetes. Among those with diabetes and hypertension, systolic and diastolic blood pressure fell by 5.66 and 8.15 mmHg, respectively (P = 0.005 and P = 0.001). Among those with diabetes and high cholesterol, total cholesterol fell by 36.41 mg/dL (P = 0.001). These improvements were projected to increase life expectancy for persons with newly diagnosed diabetes by 1.0 year. Conclusions Risk factor control has improved in the United States. Persons newly diagnosed with type 2 diabetes in 2005 have a better prognosis than persons diagnosed with diabetes 11 years earlier.
The Dark Disk of the Milky Way

Massive satellite accretions onto early galactic disks can lead to the deposition of dark matter in disk-like configurations that co-rotate with the galaxy. This phenomenon has potentially dramatic consequences for dark matter detection experiments. We utilize focused, high-resolution simulations of accretion events onto disks designed to be Galaxy analogues, and compare the resultant disks to the morphological and kinematic properties of the Milky Way's thick disk in order to bracket the range of co-rotating accreted dark matter. In agreement with previous results, we find that the Milky Way's merger history must have been unusually quiescent compared to median LAMBDA cold dark matter expectations and, therefore, its dark disk must be relatively small: the fraction of accreted dark disk material near the Sun is about 20% of the host halo density or smaller and the co-rotating dark matter fraction near the Sun, defined as particles moving with a rotational velocity lag less than 50 km s{sup -1}, is enhanced by about 30% or less compared to a standard halo model. Such a dark disk could contribute dominantly to the low energy (of order keV for a dark matter particle with mass 100 GeV) nuclear recoil event rate of direct detection experiments,more » but it will not change the likelihood of detection significantly. These dark disks provide testable predictions of weakly interacting massive particle dark matter models and should be considered in detailed comparisons to experimental data. Our findings suggest that the dark disk of the Milky Way may provide a detectable signal for indirect detection experiments, contributing up to about 25% of the dark matter self-annihilation signal in the direction of the center of the Galaxy, lending the signal a noticeably oblate morphology.« less
Refractive Surgery for High Bilateral Myopia in Children with Neurobehavioral Disorders: 1. Clear Lens Extraction and Refractive Lens Exchange

Introduction: A subpopulation of children with high myopia and neurobehavioral disorders is noncompliant with spectacle wear and ill-suited to correction using contact lenses. We report the results of refractive surgery in a series of these children treated using lensectomy alone (clear lens extraction), or lensectomy with simultaneous implantation of an intraocular lens (refractive lens exchange). Methods: Clinical course and outcome data were collated prospectively in a group of 13 children (mean age 10.4 years, range 1 to 18 years) with neurobehavioral disorders exacerbated by chronic noncompliance with spectacle wear, causing profoundly low functional vision. Myopia in the 26 eyes ranged from −14.25 to −26.00 D (mean −19.1 D). Goal refraction was approximately +1 D. Correction was achieved by lensectomy alone in 10 eyes, and lensectomy with intraocular lens implantation in 16 eyes. Primary posterior capsulectomy/subtotal vitrectomy was performed during the primary procedure in 11 eyes (42%). Mean follow-up was 4.5 years (range 1.3 to 7.5 years). Results: Myopia correction averaged 19.9 D. Eighty-one percent (21 eyes) were corrected to within ±2 D of goal refraction and the remaining 19% (5 eyes) to within ±4 D. Uncorrected acuity improved substantially (ie, an average 2 log units) in all 26 eyes, with commensurate gains in behavior and environmental visual interaction in 88% of children (14/16). Myopic regression averaged −0.16 D/year. Capsular regrowth and/or opacification necessitated vitrector or YAG-laser membranectomy in 12 eyes (46%). Focal retinal detachment (successfully repaired) occurred after eye contusion in one eye (4%) with cicatricial retinopathy of prematurity. Conclusions: Bilateral refractive lensectomy is effective for improving functional vision in neurobehaviorally impaired children who have high myopia (beyond the range of excimer laser correction: see companion publication) and difficulties wearing glasses. Posterior capsule regrowth/opacification is common, necessitating secondary membranectomy. Further study is indicated to determine the long-term safety of this procedure in similar pediatric populations.
Synthesis of Polyaniline Nanofibers by “Nanofiber Seeding”

Seeding a conventional chemical oxidative polymerization of aniline with even very small amounts of biological, inorganic, or organic nanofibers (usually <1%) dramatically changes the morphology of the resulting doped electronic polymer polyaniline from nonfibrillar (particulate) to almost exclusively nanofibers. The nanoscale morphology of the original seed template is transcribed almost quantitatively to the bulk precipitate. These findings could have immediate impact in the design and development of high-surface area electronic materials.
Radiative transfer modeling of compositions of lunar pyroclastic deposits

[1] While over 100 lunar pyroclastic deposits have been identified remotely, their compositions remain poorly constrained. In this work, we determine the compositions of three lunar regional pyroclastic deposits which are likely to contain large amounts of glass and for which we have high-quality ground-based spectra: the Aristarchus Plateau, Mare Humorum, and Sulpicius Gallus. We use radiative transfer theory and employ measured optical constants of glasses to predict the bidirectional reflectance of a particulate glass surface as a function of Fe and Ti concentration, particle size, and maturity in order to find the best spectral match to the remotely observed deposits. Tools are not available to model the optical effects of the unusual geometries of the ilmenite laths in the black beads, so we address their effects on spectra of the regional pyroclastic deposits using computational mixing. We find that model spectra of pure glass (as opposed to devitrified black beads) provide good matches to all three regions. Radiative transfer modeling predicts iron contents of 21, 20, and 17 wt% FeO for Aristarchus, Humorum, and Sulpicius Gallus, respectively, and suggests that all three regions are low in titanium, a result supported by Lunar Prospector neutron spectrometer data. However, we find that a moderate Ti glass mixed with a small fraction of black beads cannot be ruled out for the Sulpicius Gallus region.
Cyclical Determinants of Brokerage Commission Rates

This study evaluates the determinants of percentage commission rates in the residential brokerage industry. The model developed here predicts that market share of the brokerage firm, property selling difficulty, and prevailing market conditions influence commission rates. Empirical analysis using a sample of 14,891 condominium transactions from the Fort Lauderdale, Florida area provides support for the model’s predictions.