cssi/SciSciGPT-SciSciNet huggingface dataset:
Analytical validation of quality control materials for Huntington’s disease examination

The expansion of molecular diagnostics using nucleic acid technologies in clinical and public health practice has increased the need for appropriate reference materials and verified quality-control materials for quality assurance, test validation, proficiency testing and the development of new examination procedures. Good laboratory practice requires the use of reference materials to establish an examination procedure and assess the variability of the results. Reference materials are also required to assess the assay on a daily basis and to normalize results collected among different laboratories. Despite the growing volume, the rapidly increasing number of tests being offered, and the necessary routine use, certified reference materials are often not available. There is a wide range of human genetic bio-assays for which there are no available traceable certified reference materials. Several initiatives have been organized to provide well-characterized quality control specimens (e.g., cell lines) with known DNA mutations for use in diagnostics. Mutations are confirmed with bi-directional DNA sequence analysis, which is considered the reference examination procedure. In the field of personalized medicine, NIST has created and validated Standard Reference Material® 2399 for fragile X examinations. Herein we describe our characterization of candidate reference materials for Huntington’s disease genetic examination. Bi-directional DNA sequencing confirmed the size of the CAG repeat contained on each allele from patient derived materials. Amplification and capillary electrophoresis of the CAG repeats had an uncertainty ranging from 2.06%CV to 7.83%CV.
Tensor generalizations of affine symmetry vectors

A definition is suggested for affine symmetry tensors, which generalize the notion of affine vectors in the same way that (conformal) Killing tensors generalize (conformal) Killing vectors. An identity for these tensors is proven, which gives the second derivative of the tensor in terms of the curvature tensor, generalizing a well-known identity for affine vectors. Additionally, the definition leads to a good definition of homothetic tensors. The inclusion relations between these types of tensors are exhibited. The relationship between affine symmetry tensors and solutions to the equation of geodesic deviation is clarified, again extending known results about Killing tensors.
On the uniqueness of the foliation of spheres of constant mean curvature in asymptotically flat 3-manifolds

In this note we study constant mean curvature surfaces in asymptotically flat 3-manifolds. We prove that, outside a given compact subset in an asymptotically flat 3-manifold with positive mass, stable spheres of given constant mean curvature are unique. Therefore we are able to conclude that the foliation of stable spheres of constant mean curvature in an asymptotically flat 3-manifold with positive mass outside a given compact subset is unique.
Amorphous and crystalline ice on the Galilean satellites: A balance between thermal and radiolytic processes

[1] The water ice on the three outermost Galilean satellites of Jupiter has a lattice structure that can vary from crystalline to amorphous. Amorphous ice is crystallized by heating, while crystalline ice is amorphized through disruption by particle radiation. We determine ice lattice order using infrared spectra from the Near Infrared Mapping Spectrometer on the Galileo Jupiter orbiter. The shape of the reflectance peak near 3.1 μm is diagnostic of the lattice order in the top micrometers of the surface. A narrow, temperature-sensitive band near 1.65 μm, from ∼1 mm depth, is missing for amorphous ice. Spectral averages of >100 pixels were used for Europa and Callisto, because of high radiation noise and small ice amounts, respectively. Model comparisons show that the surface ice is predominantly amorphous on Europa and predominantly crystalline on Callisto, while both types of ice are found on Ganymede. The distribution of Ganymede ice properties shows a broad global pattern of more amorphous ice in the high-latitude Jovian-facing hemisphere and in the low-latitude trailing hemisphere. The ice at ∼1 mm depth on all three satellites is predominantly crystalline. The radiation flux increases by ∼300 times between Callisto and Europa, while the thermal crystallization rate may vary over five orders of magnitude among the three satellites (being the fastest at Callisto). The occurrence of crystalline and amorphous ice suggests a balance between the disruption and crystallization, with Callisto dominated by thermal crystallization and Europa by radiative disruption, and with nearly equal rates between the two processes at Ganymede.
Computational phase-field modeling of defect interactions in ferroelectrics

A continuum thermodynamics framework is presented to model the evolution of domain structures in active/smart materials. To investigate the consequences of the theories, fundamental defect interactions are studied. A principle of virtual work is specified for the theory and is implemented to devise a finite element formulation. For ferroelectrics, the theory and numerical methods are used to investigate the interactions of 180° and 90° domain walls with arrays of charged defects and dislocations to determine how strongly domain walls are electromechanically pinned by the arrays of defects. Additionally, the problems of nucleation and growth of domains from crack tips, and the propagation of domain needles are studied. The importance of adaptive mesh refinement and coarsening is discussed in the context of this modeling approach.
Sensitivity analysis of limit cycle oscillations

Many unsteady problems equilibrate to periodic behavior. For these problems the sensitivity of periodic outputs to system parameters are often desired, and must be estimated from a finite time span or frequency domain calculation. Sensitivities computed in the time domain over a finite time span can take excessive time to converge, or fail altogether to converge to the periodic value. Additionally, finite span outputs can exhibit local extrema in parameter space which the periodic outputs they approximate do not, hindering their use in optimization. We derive a theoretical basis for this error and demonstrate it using two examples, a van der Pol oscillator and vortex shedding from a low Reynolds number airfoil. We show that output windowing enables the accurate computation of periodic output sensitivities and may allow for decreased simulation time to compute both time-averaged outputs and sensitivities. We classify two distinct window types: long-time, over a large, not necessarily integer number of periods; and short-time, over a small, integer number of periods. Finally, from these two classes we investigate several examples of window shape and demonstrate their convergence with window size and error in the period approximation, respectively.
Reviewing the evidence for pentaquarks

Several experimental groups have reported evidence for baryons with flavor exotic quantum numbers that cannot be explained as qqq bound states but require a minimum of five quarks - qqqq. These pentaquark states include the θ+, the Ξ−− and the θc. The reported widths of these new states are consistent with experimental resolution and may be as narrow as a few MeV/c2 or less. Prior to 2003, experimental searches for flavor exotic baryons spanning several decades yielded negative results. There have also been a number of searches carried out since the reports of these new pentaquark states that do not confirm their existence. This review of both the positive and negative reports seeks to understand the current situation regarding the experimental evidence for pentaquarks.
Study of critical slowing-down in SU(2) Landau gauge fixing

Abstract We study the problem of critical slowing-down for gauge-fixing algorithms (Landau gauge) in SU (2) lattice gauge theory on 2 and 4 dimensional lattices, both numerically and analytically. We consider five such algorithms, and we measure four different observables. A detailed discussion and analysis of the tuning of these algorithms is also presented.
Preparation and multinuclear NMR and IR spectroscopic characterization of some complexes of acetyldiphenylphosphine, diphenyl(2-thienyl)phosphine, bis(2-thienyl)phenylphosphine and cyanodiphenylphosphine

Abstract The syntheses and multinuclear NMR and IR spectroscopic characterizations of some mononuclear Mo, Pd and Pt complexes of acetyldiphenylphosphine, diphenyl(2-thienyl)phosphine, bis(2-thienyl)phenylphosphine and cyanodiphenylphosphine are presented. The NMR and IR spectra of the Mo carbonyl complexes indicate that the electron-donor ability of the P substituents increases in the order CN
Lifts of Partial Characters with Respect to a Chain of Normal Subgroups

In this paper, we consider lifts of π-partial characters with the property that the irreducible constituents of their restrictions to certain normal subgroups are also lifts. We will show that such a lift must be induced from what we call an inductive pair, and every character induced from an inductive pair is such a lift. With this condition, we will get a lower bound on the number of such lifts.
Complexation of osmium tetroxide with tertiary amines

We report data on the rate of formation of OsO4 complexes with tetramethylethylenediamine and two phenanthrolines. Buffer and pH effects and energies of activation were studied as well. Data for the stoichiometry of OsO4·L complexes and stability constants are reported for these as well as other ligands. 1H NMR chemical shifts were determined for three OsO4·pyridine complexes.
Missile and spacecraft coning instabilities

Abstract : The destabilizing effect of yaw or Magnus-type moments on the angle-of-attack behavior of spinning missiles is well known to the missile designer. Yaw moments can also have a destabilizing (or stabilizing) effect on the attitude or coning motion of spinning spacecraft. The analogy might not be readily apparent because of the difference between the angle of attack of a spinning missile in atmospheric flight and the coning angle of spin-stabilized spacecraft. A concise treatment of the dynamics associated with coning instabilities is presented, and illustrative examples of classical missile and spacecraft coning instabilities are reviewed.
Applications of the Brauer Complex: Card Shuffling, Permutation Statistics, and Dynamical Systems

By algebraic group theory, there is a map from the semisimple conjugacy classes of a finite group of Lie type to the conjugacy classes of the Weyl group. Picking a semisimple class uniformly at random yields a probability measure on conjugacy classes of the Weyl group. Using the Brauer complex, it is proved that this measure agrees with a second measure on conjugacy classes of the Weyl group induced by a construction of Cellini using the affine Weyl group. Formulas for Cellini's measure in type A are found. This leads to new models of card shuffling and has interesting combinatorial and number-theoretic consequences. An analysis of type C gives another solution to a problem of Rogers in dynamical systems: the enumeration of unimodal permutations by cycle structure. The proof uses the factorization theory of palindromic polynomials over finite fields. Contact is made with symmetric function theory.
Covering Nearly Surface-Embedded Graphs with a Fixed Number of Balls

A recent result of Chepoi et al. [Discrete Comput. Geom. 37(2):237–244, 2007] states that any planar graph of diameter at most $$2R$$ 2 R can be covered by a constant number of balls of size $$R$$ R ; put another way, there are a constant-sized subset of vertices within which every other vertex is distance half the diameter. We generalize this result to graphs embedded on surfaces of fixed genus with a fixed number of apices, making progress toward the conjecture that graphs excluding a fixed minor can also be covered by a constant number of balls. To do so, we develop two tools which may be of independent interest. The first gives a bound on the density of graphs drawn on a surface of genus $$g$$ g having a limit on the number of pairwise-crossing edges. The second bounds the size of a non-contractible cycle in terms of the Euclidean norm of the degree sequence of a graph embedded on surface.
A general synthesis of 2-alkoxy-2-phenylpropanoic acids

Abstract A preparation of a variety of 2-alkoxy-2-phenylpropanoic acids in two steps is described. Epoxidation of α-methylstyrene with mCPBA in methanol or primary alcohol solvents proceeded with an acid-catalyzed in situ ring opening reaction to give the corresponding 2-alkoxy-2-phenyl-1-propanols in 28–91% yield. Lower yields were realized with secondary (22–58%) and tertiary (14%) alcohols. These alcohols were cleanly oxidized to the corresponding carboxylic acids using a mild Heyns' oxidation (O2, Pt/C) in generally good to excellent yields (25–92%). The derived (S)-α-methylbenzylamide diastereomers are nearly all well separated by capillary GC, and the use of this method to determine the enantiomeric purity of brucine-resolved 2-methoxy-2-phenylpropanoic acid was demonstrated.
Fusion categories of rank 2

We classify semisimple rigid monoidal categories with two isomorphism classes of simple objects over the field of complex numbers. In the appendix written by P.Etingof it is proved that the number of semisimple Hopf algebras with a given finite number of irreducible representations is finite.
Dark Matter Direct Search Rates in Simulations of the Milky Way and Sagittarius Stream

We analyze self-consistent N-body simulations of the Milky Way disk and the ongoing disruption of the Sagittarius dwarf satellite to study the effect of Sagittarius tidal debris on dark matter detection experiments. In agreement with significant previous work, we reiterate that the standard halo model is insufficient to describe the non-Maxwellian velocity distribution of the Milky Way halo in our equilibrium halo-only and halo/galaxy models, and offer suggestions for correcting for this discrepancy. More importantly, we emphasize that the dark matter component of the leading tidal arm of the Sagittarius dwarf is significantly more extended than the stellar component of the arm, and also that the dark matter and stellar streams are not necessarily coaxial and may be offset by several kpc at the point at which they impact the Galactic disk. This suggests that the dark matter component of the Sagittarius debris is likely to have a non-negligible influence on dark matter detection experiments even when the stellar debris is centered several kpc from the solar neighborhood. Relative to models without an infalling Sagittarius dwarf, the Sagittarius dark matter debris in our models induces an energy-dependent enhancement of direct search event rates of as much as ~ 20–45%, an energy-dependent reduction in the amplitude of the annual modulation of the event rate by as much as a factor of two, a shift in the phase of the annual modulation by as much as ~ 20 days, and a shift in the recoil energy at which the modulation reverses phase. These influences of Sagittarius are of general interest in the interpretation of dark matter searches, but may be particularly important in the case of relatively light (mχ20 GeV/c2) dark matter because the Sagittarius stream impacts the solar system at high speed compared to the primary halo dark matter.
Sc5Ni2Te2: Synthesis, Structure, and Bonding of a Metal−Metal-Bonded Chain Phase, a Relative of Gd3MnI3

Sc{sub 5}Ni{sub 2}Te{sub 2} has been prepared by high-temperature solid-state techniques and the structure determined at 23 C by single crystal and powder X-ray diffraction methods to be orthorhombic. The structure contains pairs of eclipsed zigzag chains of nickel atoms that are sheathed by scandium atoms and demarcated from other chains by tellurium atoms. The structure is isotypic with that of Hf{sub 5}Co{sub 1+x}P{sub 3{minus}x}, but shifted atomic positions and a different ordering of the main group and late transition elements give it a clearly 1D character. The differences in dimensionality, ordering, and bonding are discussed, and comparisons are made with Gd{sub 3}MnI{sub 3} and rare-earth-metal cluster halides in general.
Mixed Lefschetz Theorems and Hodge-Riemann Bilinear Relations

The Hard Lefschetz Theorem (HLT) and the Hodge-Riemann bilinear relations (HRR) hold in various contexts: they impose restrictions on the cohomology algebra of a smooth compact Kahler manifold; they restrict the local monodromy of a polarized variation of Hodge structure; they impose conditions on the f-vectors of convex polytopes. While the statements of these theorems depend on the choice of a Kahler class, or its analog, there is usually a cone of possible choices. It is then natural to ask whether the HLT and HRR remain true in a mixed context. In this note, we present a unified approach to proving the mixed HLT and HRR, generalizing the known results, and proving it in new cases, such as the intersection cohomology of nonrational polytopes.
Impedance, axial-ratio, and receive-power bandwidths of microstrip antennas

Closed-form expressions for the impedance and axial-ratio bandwidths of a single-feed circularly polarized microstrip antenna have been derived. Receive-power bandwidths for both linearly and circularly polarized microstrip antennas have also been derived, which quantify the bandwidths when the microstrip antennas are used as receivers. The microstrip antennas are assumed to be probe fed and are modeled as RLC circuits (neglecting the probe inductances). For circular polarization, the probe feed is assumed to be along a 45/spl deg/ line across the microstrip antenna such that two orthogonal modes are identical in magnitude and in phase quadrature at the center frequency. Although derived for microstrip antennas, the expressions for impedance, axial-ratio, and receive-power bandwidth are also valid for other high-Q resonant antenna structures having an impedance behavior that is approximated by the same type of RLC circuits.
Differential flatness of two one-forms in arbitrary number of variables

Given a differentially flat system of ODEs, flat outputs that depend only on original variables but not on their derivatives are called zero-flat outputs and systems possessing such outputs are called zero-flat. In this paper we present a theory of zero-flatness for a system of two one-forms in arbitrary number of variables (t,x1,…,xN). Our approach splits the task of finding zero-flat outputs into two parts. First part involves solving for distributions that satisfy a set of algebraic conditions. The second part involves finding an integrable distribution from the solution set of the first part. Typically this part involves solving PDEs. Our results are also applicable in determining if a control affine system in n states and n−2 controls has flat outputs that depend only on states. We illustrate our method by examples.
A Photometric and Spectroscopic Search for White Dwarfs in the Open Clusters NGC 6633 and NGC 7063

We present photometric and spectroscopic studies of the white dwarf (WD) populations in the intermediate-age open clusters NGC 6633 and NGC 7063 as part of the ongoing Lick-Arizona White Dwarf Survey. Using wide-field CCD imaging, we locate 41 candidate WDs in the two cluster fields: 32 in NGC 6633, and 9 in NGC 7063. Spectroscopic observations confirm 13 of these candidates to be bona fide WDs. We describe in detail our Balmer-line fitting technique for deriving effective temperatures and surface gravities from optical DA WD spectra and apply the technique to the 11 DA WDs in the sample. Of these, only two DA WDs are at the cluster distance moduli, one in each cluster. Two more DAs lie 0.75 mag foreground to NGC 6633, raising the possibility that these are double degenerate systems in the cluster. If they are nearly equal-mass binaries, both of these systems likely have combined masses above the Chandrasekhar limit. One DB WD is found to be consistent with membership in NGC 6633, which would make this the third confirmed He-atmosphere WD in an open cluster, although further data are needed to confirm cluster membership. The WD consistent with membership in the cluster NGC 7063 has a low mass (≈0.4 M⊙), suggesting it may be a He-core WD resulting from close binary evolution. Three of the 11 hydrogen-atmosphere WDs in this study are observed to have Ca II absorption; the number of DAZs in this study is consistent with previous observations that ~25% of field WDs are DAZs.
Proton-proton fusion in leading order of effective field theory

Abstract Using a recently developed effective field theory for the interactions of nucleons at non-relativistic energies, we calculate the rate for the fusion process p + p → d + e + + ν e to leading order in the momentum expansion. Coulomb effects are included non-perturbatively in a systematic way. The resulting rate is independent of specific models for the strong interactions at short distances and is in agreement with the standard result in the zero-range approximation.
True trees are dense

We show that any compact, connected set K in the plane can be approximated by the critical points of a polynomial with two critical values. Equivalently, K can be approximated in the Hausdorff metric by a true tree in the sense of Grothendieck’s dessins d’enfants.
Bureaucratic productivity: The case of agricultural research

Among the most consistent themes in the new literature on public economics is the inference that the output of bureaucratic services tends to be excessive, both (a) relative to the equilibrium level of output if the same services were provided by private firms operating in a competitive market and (b) relative to the level of output preferred by the typical legislator and the typical voter. This perspective is perhaps most fully developed in the work of William A. Niskanen, Jr. (1968, 1971, 1975).1 It has become pervasive among a broad segment of the public economics school (Borcherding, 1977). The purpose of this paper is to confront the excess supply hypothesis with the large body of evidence that has accumulated on the rate of return to public sector agricultural research.
Simple holographic duals to boundary CFTs

By relaxing the regularity conditions imposed in arXiv:1107.1722 on half-BPS solutions to six-dimensional Type 4b supergravity, we enlarge the space of solutions to include two new half-BPS configurations, which we refer to as the AdS2-cap and the AdS2-funnel. We give evidence that the AdS2-cap and AdS2-funnel can be interpreted as fully back-reacted brane solutions with respectively AdS2 and AdS2 × S 2 world volumes. AdS2-cap and AdS2-funnel solutions with a single asymptotic AdS3 × S 3 region are constructed analytically. We argue that AdS2-cap solutions provide simple examples of holographic duals to boundary CFTs in two dimensions and present calculations of their holographic boundary entropy to support the BCFT dual picture.
Business-Cycle Phases and Their Transitional Dynamics

This article examines differences in expansionary and contractionary phases of the business cycle. By extending the nonlinear Markov-switching estimation method of Hamilton to incorporate time-varying probabilities of transitions between the phases, the marginal benefits of the time-varying transition probability Markov-switching model are highlighted. Using this technique, I document the high correlation between the evolution of the phases inferred from the model and traditional reference cycles for monthly output data. Many of the economic variables that determine the time-varying probabilities help to predict turning points. The predictive power of standard leading indicators is evaluated and compared.
Electrostatic space radiation shielding

Abstract For the success of NASA’s new vision for space exploration to Moon, Mars and beyond, exposures from the hazards of severe space radiation in deep space long duration missions is ‘a must solve’ problem. The payload penalty demands a very stringent requirement on the design of the spacecrafts for human deep space missions. The exploration beyond low Earth orbit (LEO) to enable routine access of space will require protection from the hazards of the accumulated exposures of space radiation, Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE), and minimizing the production of secondary radiation is a great advantage. There is a need to look to new horizons for newer technologies. The present investigation revisits electrostatic active radiation shielding and explores the feasibility of using the electrostatic shielding in concert with the state-of-the-art materials shielding and protection technologies. The full space radiation environment has been used, for the first time, to explore the feasibility of electrostatic shielding. The goal is to repel enough positive charge ions so that they miss the spacecraft without attracting thermal electrons. Conclusions are drawn for the future directions of space radiation protection.
The battle for the “green” polymer. Different approaches for biopolymer synthesis: bioadvantaged vs. bioreplacement

Biopolymers have been used throughout history; however, in the last two centuries they have seen a decrease in their utilization as the proliferation of inexpensive and mass-produced materials from petrochemical feedstocks quickly became better-suited to meeting society's needs. In recent years, high petroleum prices and the concern of society to adopt greener and cleaner products has led to an increased interest in biorenewable polymers and the use of sustainable technologies to produce them. Industrial and academic researchers alike have targeted several routes for producing these renewable materials. In this perspective, we compare and contrast two distinct approaches to the economical realization of these materials. One mentality that has emerged we term "bioreplacement", in which the fields of synthetic biology and catalysis collaborate to coax petrochemical monomers from sugars and lignocellulosic feedstocks that can subsequently be used in precisely the same ways to produce precisely the same polymers as we know today. For example, the metabolic engineering of bacteria is currently being explored as a viable route to common monomers such as butadiene, isoprene, styrene, acrylic acid, and sebacic acid, amongst others. Another motif that has recently gained traction may be referred to as the "bioadvantage" strategy, where the multifunctional "monomers" given to us by nature are combined in novel ways using novel chemistries to yield new polymers with new properties; for these materials to compete with their petroleum-based counterparts, they must add some advantage, for example less cost. For instance, acrylated epoxidized soybean oil readily undergoes polymerization to thermosets and recently, thermoplastic rubbers. Additionally, many plants produce pre-polymeric or polymeric materials that require little or no post modification to extract and make use of these compounds.
Computer processing of tunable diode laser spectra

A computer-controlled tunable diode laser spectrometer and spectral analysis software are described. The three-channel system records simultaneously the transmission of a subject gas, a temperature-stabilized etalon, and a calibration gas. The software routines are applied to diode laser spectra of HNO3 and NO2 to illustrate the procedures adopted for conversion of raw spectral data to useful transmission and harmonic spectra. Extraction of line positions, absorption intensities, collisional broadening coefficients, and gas concentrations from recorded spectra is also described.
The Problematic Role of ‘Irreversibility’ in the Definition of Death

Most definitions of death--whether cardiopulmonary, whole brain and brain stem, or just upper brain--include an irreversibility condition. Cessation of function is not enough to declare death. Irreversibility should be limited to an organism's ability to 'restart' itself after vital organs have ceased to function. However, this would mean that every hour people who cannot be revived without the intervention of medical personnel and their technology are coming back from the dead. However, the alternative of irreversibility being dependent upon technology will lead to even more counterintuitive results such as: some people are dead at a particular time and place, but others in more technologically advanced eras and locations are alive despite their being in identical physical states; in the future, millions of cryogeneically frozen human beings could spend centuries in a non-dead state because of the future technological breakthroughs; or large numbers of 'frozen' people are dead for aeons but coroners are not able to declare them so because they are unaware of what biological conditions science will never be able to reverse. So death should be defined only in non-relational biological terms, with a self-starting condition similar to that once advocated by Lawrence Becker.
The Evolution and Structure of Early-Type Field Galaxies: A Combined Statistical Analysis of Gravitational Lenses

We introduce a framework for simultaneously investigating the structure and luminosity evolution of early-type gravitational lens galaxies. The method is based on the fundamental plane, which we interpret using the aperture mass-radius relations derived from lensed image geometries. We apply this method to our previous sample of 22 lens galaxies with measured redshifts and excellent photometry. Modeling the population with a single mass profile and evolutionary history, we find that early-type galaxies are nearly isothermal (logarithmic density slope n = 2.06 ± 0.17, 68% C.L.) and that their stars evolve at a rate of d log(M/L)B/dz = -0.50 ± 0.19 (68% C.L.) in the rest-frame B band. For a Salpeter initial mass function and a concordance cosmology, this implies a mean star formation redshift of zf > 1.5 at 95% confidence. While this model can neatly describe the mean properties of early-type galaxies, it is clear that the scatter of the lens sample is too large to be explained by observational uncertainties alone. We therefore consider statistical models in which the galaxy population is described by a distribution of star formation redshifts. We find that stars must form over a significant range of redshifts (Δzf > 1.7, 68% C.L.), which can extend as low as zf ~ 1 for some acceptable models. However, the typical galaxy will still have an old stellar population (zf > 1.5). The lens sample therefore favors early star formation in field ellipticals, even if we make no a priori assumption regarding the shape of the mass distribution in lenses and include the range of possible deviations from homology in the uncertainties. Our evolution results call into question several recent claims that early-type galaxies in low-density environments have much younger stars than those in rich clusters.
Obstacle recognition using region-based color segmentation techniques for mobile robot navigation

This work has been performed in conjunction with the ECE Department's autonomous vehicle entry in the 2006 Intelligent Ground Vehicle Competition (www.igvc.org). The course to be traversed in the competition consists of a lane demarcated by paint lines on grass along with other challenging artifacts such as a sandpit, a ramp, potholes, colored tarps, and obstacles set up using orange and white construction barrels. In this paper an enhanced obstacle detection and mapping algorithm based on region-based color segmentation techniques is described. The main purpose of this algorithm is to detect obstacles which are not properly identified by the LADAR (Laser Detection and Ranging) system optimally mounted close to the ground, due to "shadowing" occasionally resulting in bad navigation decisions. On the other hand, the camera that is primarily used to detect the lane lines is mounted at 6 feet. In this work we concentrate on the identification of orange/red construction barrels. This paper proposes a generalized color segmentation technique which is potentially more versatile and faster than traditional full or partial color segmentation approaches. The developed algorithm identifies the shadowed items within the camera's field of vision and uses this to complement the LADAR information, thus facilitating an enhanced navigation strategy. The identification of barrels also aids in deleting bright objects from images which contain lane lines, which improves lane line identification.
A dynamic bootstrap mechanism for rendezvous-based multicast routing

Current multicast routing protocols can be classified into three types according to how the multicast tree is established: broadcast and prune (e.g., DVMRP, PIM-DM), membership advertisement (e.g., MO-SPF), and rendezvous-based (e.g., CBT, PIM-SM). Rendezvous-based protocols associate with each logical multicast group address, a physical unicast address, referred to as the 'core' or 'rendezvous point' (RP). Members first join a multicast tree rooted at this rendezvous point in order to receive data packets sent to the group. Rendezvous mechanisms are well suited to large wide-area networks because they distribute group-specific data and membership information only to those routers that are on the multicast distribution tree. However, rendezvous protocols require a bootstrap mechanism to map each logical multicast address to its current physical rendezvous point address. The bootstrap mechanism must adapt to network and router failures but should minimize unnecessary changes in the group-to-RP mapping. In addition, the bootstrap mechanism should be transparent to the hosts. This paper describes and analyzes the bootstrap mechanism developed for PIM-SM. The mechanism employs an algorithmic mapping of multicast group to rendezvous point address, based on a set of available RPs distributed throughout a multicast domain. The primary evaluation measures are convergence time, message distribution overhead, balanced assignment of groups to RPs, and host impact. The mechanism as a whole, and the design lessons in particular, are applicable to other rendezvous-based multicast routing protocols as well.
The effects of government-industry R&D programs on private R&D: the case of the Small Business Innovation Research Program

I ask whether government-industry commercial R&D grants increase private R&D. Regressing some measure of innovation on the subsidy can establish a correlation between grants and R&D, but it cannot determine whether grants increase firm R&D or whether firms that do more R&D received more grants. Using a dataset of firms involved in the Small Business Innovation Research (SBIR) program, I estimate a multi-equation model to test these hypotheses. Firms with more employees and that appear to do more research win more SBIR grants, but the grants do not affect employment. Moreover, I find evidence that the grants crowd out firm-financed R&D spending dollar for dollar.
Chaos and Elliptical Galaxies

Recent results on chaos in triaxial galaxy models are reviewed. Central mass concentrations like those observed in early-type galaxies — either stellar cusps, or massive black holes — render most of the box orbits in a triaxial potential stochastic. Typical Liapunov times are 3–5 crossing times, and ensembles of stochastic orbits undergo mixing on timescales that are roughly an order of magnitude longer. The replacement of the regular orbits by stochastic orbits reduces the freedom to construct self-consistent equilibria, and strong triaxiality can be ruled out for galaxies with sufficiently high central mass concentrations.
Do Social Connections Reduce Moral Hazard? Evidence from the New York City Taxi Industry

This study investigates the role of social networks in aligning the incentives of agents in settings with incomplete contracts. Specifically, the study examines the New York City taxi industry where taxis are often leased and lessee-drivers have worse driving outcomes than owner-drivers due to moral hazard. Using within-driver variation and instrumental variable strategies to remove selection, we find that drivers leasing from members of their country-of-birth community exhibit significantly reduced effects of moral hazard, representing an improvement of almost one-half of a standard deviation of the outcome measures. Screening is ruled out as an explanation, and other mechanisms are investigated. (JEL D82, D86, L92, Z13)
Copper sulfate-pentahydrate-1,10-phenanthroline catalyzed amidations of alkynyl bromides. Synthesis of heteroaromatic amine substituted ynamides.

A practical cross-coupling of amides with alkynyl bromides using catalytic CuSO4·5H2O and 1,10-phenanthroline is described here. This catalytic protocol is more environmentally friendly than the use of CuCN or copper halides and provides a general entry for syntheses of ynamides including various new sulfonyl and heteroaromatic amine substituted ynamides. Given the interest in ynamides, this N-alkynylation of amides should be significant for the future of ynamides in organic synthesis.
Public financing of pain management: leaky umbrellas and ragged safety nets.

The United States, unlike all other industrialized nations, does not have a comprehensive public system for financing health care. Nevertheless, the magnitude of America's public health care financing effort is remarkable. Of the one trillion dollars the United States spent on health care in 1996, almost half, $147.7 billion, respectively. The payment policies of these massive public health care programs have a profound effect on the provision of health care. Many of the recipients of Medicare and Medicaid suffer pain. In 1994, 376,200 Americans over age sixty-five died of cancer. Virtually all of these would have been Medicare recipients, and as many as 70 percent of them died in unrelieved pain. Nearly four million Americans over sixty-five endured the pain of inpatient surgery in 1995, again nearly all of whom were Medicare recipients.
Integrating Projects from Multiple Open Source Code Forges

Much of the data about free, libre, and open source (FLOSS) software development comes from studies of code forges or code repositories used for managing projects. This paper presents a method for integrating data about open source projects by way of matching projects (entities) across multiple code forges. After a review of the relevant literature, a few of the methods are chosen and applied to the FLOSS domain, including a comparison of some simple scoring systems for pairwise project matches. Finally, the paper describes limitations of this approach and recommendations for future work.
Magnetic interactions in the metallic phase of the copper oxides: A Fermi-liquid description

One of the central issues in the field of high-temperature superconductivity is whether the normal state can be described by Fermi-liquid theory. Recent photoemission experiments along with a growing body of Fermi-liquid-based theoretical work have provided some support for this viewpoint. However, one major concern in ascertaining the validity of a Fermi-liquid approach is whether the magnetic interactions in the metallic cuprates are sufficiently strong so as to undermine the usual Fermi-liquid description. In this paper we address this question by examining the nature of the magnetic interactions in the metallic state. These interactions, which are dominantly between the Cu spins, arise via the intermediating oxygenlike states. Since the oxygen character changes as the hole doping is increased, it is expected that the Cu-Cu interactions are doping sensitive and evolve away from their value in the insulating limit. We deduce these interactions within a physical picture in which the Cu {ital d} electrons are nearly localized and the oxygen bandwidth assumes a finite value. While our qualitative results are general, we use a 1/{ital N} expansion as a convenient theoretical tool. In the extended Hubbard Hamiltonian the exchange terms are evaluated at order (1/{ital N}{sup 2}). Both superexchange ({ital J}{submore » {ital S}}) and Ruderman-Kittel-Kasuya-Yosida interactions ({ital J}{sub {ital R}}) emerge on a similar footing. With increasing carrier concentration, {ital J}{sub {ital S}} decreases rapidly, while {ital J}{sub {ital R}} abruptly increases from zero. We find that, because of the reduction in the strength of the superexchange, there is an enhanced stability of the Fermi-liquid phase. The dynamical susceptibility is also calculated within this scheme and the consequences for NMR and neutron experiments are discussed elsewhere.« less
A Theoretical Inquiry Into Aspects of the Structure and the Management of Ecological-Economic Systems

We use the theory of continuous-time Markov chains (CTMCs) to analyze hitherto unstudied questions about jointly determined ecological–economic systems. Two specific questions are examined. First, on the methodological front, we show how the theory of CTMCs can be used to effectively model dynamic and stochastic ecological–economic systems. Then, given recent concern about the sustainability of desirable states and lock-in into undesirable states, we partition the state space of our stylized ecological–economic system into good and bad states, and demonstrate the formal relationship between these two sets of states. Second, we discuss a way of looking at the task of managing ecological–economic systems that captures this formal link between the good and the bad states, and has other desirable properties.
Surface intervalley scattering on GaAs(110) studied with picosecond laser photoemission

Abstract Laser-based photoemission sources provide the unique opportunity to study dynamic electronic processes at surfaces and interfaces. Using angle-resolved, laser photoemission with Г . The momentum resolution of our experiment has permitted us to isolate the dynamic electron population changes at both Г and X and to deduce the scattering time between the two valleys.
Suzuki-Miyaura Cross-Coupling of Unprotected, Nitrogen-Rich Heterocycles: Substrate Scope and Mechanistic Investigation

The Suzuki-Miyaura cross-coupling of unprotected, nitrogen-rich heterocycles using precatalysts P1 or P2 is reported. The procedure allows for the reaction of variously substituted indazole, benzimidazole, pyrazole, indole, oxindole, and azaindole halides under mild conditions in good to excellent yields. Additionally, the mechanism behind the inhibitory effect of unprotected azoles on Pd-catalyzed cross-coupling reactions is described based on evidence gained through experimental, crystallographic, and theoretical investigations.
Field Validation of Nomad's Robotic Locomotion

During June and July of 1997, a mobile robot named Nomad traversed 223km in the Atacama Desert of southern Chile via transcontinental teleoperation. This unprecedented accomplishment is primarily attributed to Nomad's innovative locomotion design which features four-wheel/all-wheel drive locomotion, a reconfigurable chassis, electronically coordinated steering, pivot-arm suspension, and body motion averaging. Nomad's locomotion was configured through systematic analysis and simulations of the robot's predicted performance in a variety of terrain negotiation scenarios. Experimental work with a single wheel apparatus was sued to determine the effect of repeated traffic and tread pattern on power draw. Field test before and during the Atacama traverse demonstrated Nomad's substantial terrainability and autonomous navigation capabilities, and validated theoretical performance projections made during its geometric configuration. Most recently, the augmentation of the internal monitoring system with a variety of sensors has enabled a much more comprehensive characterization of Nomad's terrain performance. Because of Nomad's unique steering design a comparison of skid and explicit steering was performed by monitoring wheel torque and power during steady state turns. This paper summarizes the process and metrics of Nomad's mobility configuration, and reports on experimental data gathered during locomotion testing.
Structural concepts for large solar concentrators

The Sunflower large solar concentrator, developed in the early 1970's, is a salient example of a high-efficiency concentrator. The newly emphasized needs for solar dynamic power on the Space Station and for large, lightweight thermal sources are outlined. Existing concepts for high efficiency reflector surfaces are examined with attention to accuracy needs for concentration rates of 1000 to 3000. Concepts using stiff reflector panels are deemed most likely to exhibit the long-term consistent accuracy necessary for low-orbit operation, particularly for the higher concentration ratios. Quantitative results are shown of the effects of surface errors for various concentration and focal-length diameter ratios. Cost effectiveness is discussed. Principal sources of high cost include the need for various dished panels for paraboloidal reflectors and the expense of ground testing and adjustment. A new configuration is presented addressing both problems, i.e., a deployable Pactruss backup structure with identical panels installed on the structure after deployment in space. Analytical results show that with reasonable pointing errors, this new concept is capable of concentration ratios greater than 2000.
Time-series implications of Friedman's Permanent Income Hypothesis

Abstract The ability of the Permanent Income Hypothesis (PIH) to explain aggregate time-series data has been seriously challenged over the last ten years based upon the implications of a version of the PIH developed by Hall (1978) and Flavin (1981). There are, however, inconsistencies between the Hall-Flavin version of the PIH and pure time-series representations of the PIH based upon Friedman's original formulation. This paper considers the force of the recent challenges to the PIH when the implications of the PIH are drawn from a Friedman-Muth version of the PIH rather than the Hall-Flavin version.
Thermodynamic Environments of Deep Convection in Atlantic Tropical Disturbances

AbstractConditional composites of dropsondes deployed into eight tropical Atlantic weather systems during 2010 are analyzed. The samples are conditioned based on cloud-top temperature within 10 km of the dropsonde, the radius from the cyclonic circulation center of the disturbance, and the stage of system development toward tropical cyclogenesis. Statistical tests are performed to identify significant differences between composite profiles. Cold-cloud-region-composite profiles of virtual temperature deviations from a large-scale instantaneous average indicate enhanced static stability prior to genesis within 200 km of the center of circulation, with negative anomalies below 700 hPa and larger warm anomalies above 600 hPa. Moist static energy is enhanced in the middle troposphere in this composite mainly because of an increase in water vapor content. Prior to genesis the buoyancy of lifted parcels within 200 km of the circulation center is sharply reduced compared to the buoyancy of parcels farther from th...
A novel, one-step annulation process for the synthesis of ring-fused 2-cyclopentenones

Abstract The reaction of the dilithio derivative of dimethyl cis -4-cyclohexen-1,2-dicarboxylate with 3-substituted propiolic acid phenyl esters proceeds via an unusual mechanistic path to generate fused bicyclic 2-cyclopentenones in a single step.
Decentralized evolutionary mechanisms for intertemporal economies: A possibility result

We consider a stationary, infinite horizon aggregative model with one consumer and one producer living in each period. A decentralized intertemporal mechanism, satisfying the following “evolutionary” property, is constructed: if the current period's producer and consumer verify their equilibrium conditions, then the allocation is actually executed, without further verification by future agents. The mechanism is based on the idea of continual planning revision. It is shown that the outcome is an intertemporally efficient allocation which maximizes the long run average of one period utilities from consumption.