cssi/SciSciGPT-SciSciNet huggingface dataset:
Next generation of aircraft coatings systems

The current generation of aircraft coatings had its basis in the polymer technologies of the 1970s and the use of chromate-based metal pretreatments and primers. There have been some incremental improvements in the epoxy and polyamide oligomers used in the primers as well as the isocyanates and flexible polyols used in topcoats, plus increases in the volume solids of the coatings to continue minimally meeting environmental requirements, but no truly new technologies have been developed and applied to aircraft coatings since that time. However, because of increasing economic and environmental pressures, this situation will soon change. Also, the U.S. Air Force is seeking a coating system that will have an ultimate lifetime of 30 years for maintenance cost control and fleet sustainability. The first change in the present coatings system will be in the pretreatments plus primers that currently constitute the metal protection system for the high strength Al alloys used for aircraft. For military aircraft, these alloys will continue to be Al 2024 T-3 and Al 7075-T6, heat-treated metals that have phase-separated regions rich in reactive metals such as Cu, Mg, and Zn. There are several new technologies now under consideration for such metal protection including conductive polymers as primers without Cr-based metal pretreatments, sol-gel based pretreatments and primers, plasma polymer metal pretreatments, and organo-modified aluminum oxide particles. Each of these technologies has shown some promise for Cr replacement, but each presently has a weakness that needs to be corrected for immediate usage. For the topcoat system, fluorinated polyols and improved use of UV-absorbers and light stabilizers will probably be the first changes implemented, with ceramer and other new crosslinking systems the most likely next polymer matrix candidates. The target for the entire coatings system is to have drastically improved wet-adhesion due to a covalently bonded system that has a gradient in composition that goes continuously from metal to metal oxide to mixed metal oxide/organic polymer to high-performance UV-stable organic polymer. The materials cost for such a system may be quite high, but the maintenance cost savings will much more than offset these costs.
Resonant transmission of electromagnetic energy through thick ferromagnetic films via phonons

Abstract The transmission lineshape is calculated for the case when the exchange shift of the field, at which sound attenuation is maximum, is comparable to the linewidth of the ferromagnetic resonance.
Obscuring Active Galactic Nuclei with Nuclear Starburst Disks

We assess the potential of nuclear starburst disks to obscure the Seyfert-like AGNs that dominate the hard X-ray background at z ~ 1. Over 1200 starburst disk models, based on the theory developed by Thompson et al., are calculated for five input parameters: the black hole mass, the radial size of the starburst disk, the dust-to-gas ratio, the efficiency of angular momentum transport in the disk, and the gas fraction at the outer disk radius. We find that a large dust-to-gas ratio, a relatively small starburst disk, a significant gas mass fraction, and efficient angular momentum transport are all important to produce a starburst disk that can potentially obscure an AGN. The typical maximum star formation rate in the disks is ~10 M☉ yr−1. Assuming no mass loss due to outflows, the starburst disks feed gas onto the black hole at rates sufficient to produce hard X-ray luminosities of 1043-1044 erg s−1. The starburst disks themselves should be detectable at mid-infrared and radio wavelengths; at z = 0.8, the predicted fluxes are ~1 mJy at 24 μm and ~10-30 μJy at 1.4 GHz. Thus, we predict a large fraction of radio/X-ray matches in future deep radio surveys. The starburst disks should be easily distinguished from AGNs in future 100 μm surveys by the Herschel Space Observatory with expected fluxes of ~5 mJy. Any AGN-obscuring starbursts will be associated with hot dust, independent of AGN heating, resulting in observable signatures for separating galactic and nuclear star formation. Finally, because of the competition between gas and star formation, nuclear starbursts will be associated with lower luminosity AGNs. Thus, this phenomenon is a natural explanation for the observed decrease in the fraction of obscured AGNs with luminosity.
A viscoplastic micromechanical model for the yield strength of nanocrystalline materials

In this paper we present a micromechanical approach based on fast Fourier transforms to study the role played by dislocation glide and grain boundary (GB) accommodation in the determination of the plastic behavior of nanostructured materials. For this, we construct unit cells representing self-similar polycrystals with different grain sizes in the nanometer range and use local constitutive equations for slip and GB accommodation. We study the effect of grain size, strain rate and pressure on the local and effective behavior of nanostructured fcc materials with parameters obtained from experiments and atomistic simulations. Predictions of a previous qualitative pressure-sensitive model for the effective yield strength behind a shock front are substantially improved by considering strain partition between slip and GB activity. Under quasiestatic conditions, assuming diffusion-controlled mechanisms at GB, the model predicts a strain-rate sensitivity increase in nanocrystalline samples with respect to the coarse-grained material of the same order as in recently published experiments.
Efficient end to end data exchange using configurable compression

We explore the use of compression methods to improve the middleware-based exchange of information in interactive or collaborative distributed applications. In such applications, good compression factors must be accompanied by compression speeds suitable for the data transfer rates sustainable across network links. Our approach combines methods that continuously monitor current network and processor resources and assess compression effectiveness, with techniques that automatically choose suitable compression techniques. By integrating these techniques into middleware, there is little need for end user involvement, other than expressing the target rates of data transmission. The resulting network- and user-aware compression methods are evaluated experimentally across a range of network links and application data, the former ranging from low end links to homes, to wide-area Internet links, to high end links in intranets, the latter including both scientific (binary molecular dynamics data) and commercial (XML) data sets. Results attained demonstrate substantial improvements of this adaptive technique for data compression over non-adaptive approaches, where better compression methods are used when CPU loads are low and/or network links are slow, and where less effective and typically, faster compression techniques are used in high end network infrastructures.
Digestive Politics in Russia: Feeling the Sensorium beyond the Palate

Accounts of the cultural aspects of food consumption have conventionally privileged acts of production and consumption rather than acts of disposal. In the case of eating, attention has been given to ingestion as the moment when cultural values are consumed and expressed, so that choice and taste preferences are presented as part of the act of consuming. As a result, the sensory dimensions of taste are located at the palate: flavor, aroma, texture, appearance, and sound. Yet processes of digestion move foods through and out of the bodies of consumers, thereby producing different sensory responses and cultural interpretations of those sensory responses. This article examines the sensory experiences of digestion through a discussion of how Russian consumers interpret digestive processes as means of engaging in and responding to larger cultural phenomena. Ultimately, by arguing for a politics of the gut, I show how cultural trends are deeply embedded in the most intimate bodily spaces of Russian consumers an...
Ultrafast photodissociation dynamics of HMX and RDX from their excited electronic states via femtosecond laser pump–probe techniques

Abstract Femtosecond laser pump–probe techniques are employed to investigate the mechanisms and dynamics of the photodissociation of HMX and RDX from their excited electronic states at three wavelengths (230 nm, 228 nm, and 226 nm). The only observed product is the NO molecule. Parent HMX and RDX ions are not observed. The NO molecule has a resonant A 2 Σ ← X 2 Π (0, 0) transition at 226 nm and off-resonance two-photon absorption at 228 nm and 230 nm. Pump–probe transients of the NO product at both off-resonance and resonance absorption wavelengths indicate the decomposition dynamics of HMX and RDX falls into the timescale of our laser pulse duration (180 fs).
Establishing non-Abelian topological order in Gutzwiller-projected Chern insulators via entanglement entropy and modular S -matrix

We use entanglement entropy signatures to establish non-Abelian topological order in projected Chern-insulator wave functions. The simplest instance is obtained by Gutzwiller projecting a filled band with Chern number $C=2$, whose wave function may also be viewed as the square of the Slater determinant of a band insulator. We demonstrate that this wave function is captured by the $\text{SU}{(2)}_{2}$ Chern-Simons theory coupled to fermions. This is established most persuasively by calculating the modular $\mathcal{S}$-matrix from the candidate ground-state wave functions, following a recent entanglement-entropy-based approach. This directly demonstrates the peculiar non-Abelian braiding statistics of Majorana fermion quasiparticles in this state. We also provide microscopic evidence for the field theoretic generalization, that the $N$th power of a Chern number $C$ Slater determinant realizes the topological order of the $\text{SU}{(N)}_{C}$ Chern-Simons theory coupled to fermions, by studying the $\text{SU}{(2)}_{3}$ (Read-Rezayi--type state) and the $\text{SU}{(3)}_{2}$ wave functions. An advantage of our projected Chern-insulator wave functions is the relative ease with which physical properties, such as entanglement entropy and modular $\mathcal{S}$-matrix, can be numerically calculated using Monte Carlo techniques.
A tetrachloro polyketide hexahydro-1H-isoindolone, muironolide A, from the marine sponge Phorbas sp. natural products at the nanomole scale.

Muironolide A, a new chemical entity with an unprecedented chlorinated hexahydro-1H-isoindolone skeleton, was isolated in only 90 μg yield from the same marine sponge, Phorbas sp. that also provide...
On parallel integer sorting

We present an optimal algorithm for sortingn integers in the range [1,nc] (for any constantc) for the EREW PRAM model where the word length isne, for any e>0. Using this algorithm, the best known upper bound for integer sorting on the (O(logn) word length) EREW PRAM model is improved. In addition, a novel parallel range reduction algorithm which results in a near optimal randomized integer sorting algorthm is presented. For the case when the keys are uniformly distributed integers in an arbitrary range, we give an algorithm whose expected running time is optimal.
Cobordism, Relative Indices and Stein Fillings

In this article we build on the framework developed in Ann. Math. 166, 183–214 ([2007]), 166, 723–777 ([2007]), 167, 1–67 ([2008]) to obtain a more complete understanding of the gluing properties for indices of boundary value problems for the Spin ℂ-Dirac operator with sub-elliptic boundary conditions. We extend our analytic results for sub-elliptic boundary value problems for the Spin ℂ-Dirac operator, and gluing results for the indices of these boundary problems to Spin ℂ-manifolds with several pseudoconvex (pseudoconcave) boundary components. These results are applied to study Stein fillability for compact, 3-dimensional, contact manifolds.
Comment on two-dimensional O( N) and Sp( N) Yang-Mills theories as string theories

We write down all orders large-N expansions for the dimensions of irreducible representations of O(N) and Sp(N). We interpret all the terms in these expansions as symmetry factors for singular worldsheet configurations, involving collapsed crosscaps and tubes. We use it to complete the interpretation of two-dimensional Yang-Mills theories with these gauge groups, on arbitrary two-dimensional manifolds, in terms of a string theory of maps of the type considered by Gross and Taylor. We point out some intriguing similarities to the case of U(N) and discuss their implications.
Branching ratio measurements of the 7.12-MeV state in 16O

Knowledge of the γ -ray branching ratios of the 7.12-MeV state of 16 O is important for the extrapolation of the 12 C( α , γ ) 16 O cross section to astrophysical energies. Ground state transitions provide most of the 12 C( α , γ ) 16 O total cross section while cascade transitions have contributions of the order of 10-20%. Determining the 7.12 → 6.92-MeV branching ratio will also result in a better extrapolation of the cascade and E 2 ground state cross section to low energies. We report here on measurements on the branching ratio of the 7.12 → 6.92-MeV transition in 16 O.
Density of Mars' south polar layered deposits.

Both poles of Mars are hidden beneath caps of layered ice. We calculated the density of the south polar layered deposits by combining the gravity field obtained from initial results of radio tracking of the Mars Reconnaissance Orbiter with existing surface topography from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor spacecraft and basal topography from the Mars Advanced Radar for Subsurface and Ionospheric Sounding on the Mars Express spacecraft. The results indicate a best-fit density of 1220 kilograms per cubic meter, which is consistent with water ice that has ∼15% admixed dust. The results demonstrate that the deposits are probably composed of relatively clean water ice and also refine the martian surface-water inventory.
Effect of Dissipation on Density Profile of One Dimensional Gas

Abstract We study the effect of dissipation on the density profile of a one-dimensional gas that is subject to gravity. The gas is in thermal equilibrium at temperature T with a heat reservoir at the bottom wall. Perturbative analysis of the Boltzmann equation reveals that the correction due to dissipation resulting from inelastic collisions is positive for 0⩽z zc with z the vertical coordinate. The numerically determined value for zc is mgzc/kBT≈1.1613, where g is the gravitational constant and m is the particle mass.
PARALLEL SYNTENIC ALIGNMENTS

Given two genomic DNA sequences, the syntenic alignment problem is to compute an ordered list of subsequences for each sequence such that the corresponding subsequence pairs exhibit a high degree of similarity. Syntenic alignments are useful in comparing genomic DNA from related species and in identifying conserved genes. In this paper, we present a parallel algorithm for computing syntenic alignments that runs in time, where m and n are the respective lengths of the two genomic sequences, and p is the number of processors used. Our algorithm is time optimal with respect to the corresponding sequential algorithm and can use processors, where n is the length of the larger sequence. The space requirement of the algorithm is per processor. Using an implementation of this parallel algorithm, we report the alignment of a gene-rich region of human chromosome 12, namely 12p13 and its syntenic region in mouse chromosome 6 (both over 220,000 base pairs in length) in under 24 minutes on a 64-processor IBM xSeries cluster.
Ipso-amidation of arylboronic acids: Xenon difluoride-nitriles as efficient reagent systems ☆

The xenon difluoride-mediated, ipso-amidation of boronic acids has been achieved for the first time under mild conditions. This method provides a simple, one-pot procedure for the direct synthesis of a series of anilides from the corresponding arylboronic acids and alkyl/aryl nitriles. Arylboronic acids bearing electron donating groups gave anilides in high yields, while moderate yields were observed for those bearing electron withdrawing groups. A plausible mechanism involving the formation of an aryl radical cation through single electron transfer by xenon difluoride, followed by the nucleophilic addition of the nitrile, is proposed.
Matrix general relativity: a new look at old problems

We develop a novel approach to gravity that we call 'matrix general relativity' (MGR) or 'gravitational chromodynamics' (GCD or GQCD for the quantum version). Gravity is described in this approach not by one Riemannian metric (i.e. a symmetric two-tensor field) but by a multiplet of such fields, or by a matrix-valued symmetric two-tensor field that satisfies certain conditions. We define the matrix extensions of standard constructions of differential geometry including connections and curvatures, and finally, an invariant functional of the new field that reduces to the standard Einstein action functional in the commutative (diagonal) case. Our main idea is the analogy with Yang–Mills theory (QCD and the standard model). We call the new degrees of freedom of gravity associated with the matrix structure 'gravitational colour' or simply 'gravicolour' and introduce a new gauge symmetry associated with this degree of freedom. As in the standard model there are two possibilities. First of all, it is possible that at high energies (say at the Planckian scale) this symmetry is exact (symmetric phase), but at low energies it is badly broken, so that one tensor field remains massless (and gives general relativity) and the other ones become massive with masses of Planckian scale. The second possibility is that the additional degrees of freedom of the gravitational field are confined to the Planckian scale. What one sees at large distances are singlets (invariants) of the new gauge symmetry.
Apollonian circle packings: Number theory II. Spherical and hyperbolic packings

Apollonian circle packings arise by repeatedly filling the interstices between mutually tangent circles with further tangent circles. In Euclidean space it is possible for every circle in such a packing to have integer radius of curvature, and we call such a packing an integral Apollonian circle packing. There are infinitely many different integral packings; these were studied in Part I (J. Number Theory 100, 1–45, 2003). Integral circle packings also exist in spherical and hyperbolic space, provided a suitable definition of curvature is used and again there are an infinite number of different integral packings. This paper studies number-theoretic properties of such packings. This amounts to studying the orbits of a particular subgroup ${\mathcal{A}}$ of the group of integral automorphs of the indefinite quaternary quadratic form $Q_{{\mathcal{D}}}(w,x,y,z)=2(w^{2}+x^{2}+y^{2}+z^{2})-(w+x+y+z)^{2}$ . This subgroup, called the Apollonian group, acts on integer solutions $Q_{{\mathcal{D}}}(w,x,y,z)=k$ . This paper gives a reduction theory for orbits of ${\mathcal{A}}$ acting on integer solutions to $Q_{{\mathcal{D}}}(w,x,y,z)=k$ valid for all integer k. It also classifies orbits for all k≡0 (mod 4) in terms of an extra parameter n and an auxiliary class group (depending on n and k), and studies congruence conditions on integers in a given orbit.
Escape problem for irreversible systems.

The problem of noise-induced escape from a metastable state arises in physics, chemistry, biology, systems engineering, and other areas. The problem is well understood when the underlying dynamics of the system obey detailed balance. When this assumption fails many of the results of classical transition-rate theory no longer apply, and no general method exists for computing the weak-noise asymptotic behavior of fundamental quantities such as the mean escape time. In this paper we present a general technique for analyzing the weak-noise limit of a wide range of stochastically perturbed continuous-time nonlinear dynamical systems. We simplify the original problem, which involves solving a partial differential equation, into one in which only ordinary differential equations need be solved. This allows us to resolve some old issues for the case when detailed balance holds. When it does not hold, we show how the formula for the asymptotic behavior of the mean escape time depends on the dynamics of the system along the most probable escape path. We also present results on short-time behavior and discuss the possibility of [ital focusing] along the escape path.
Anodic oxidation reactions: the total synthesis of (+)-nemorensic acid

Abstract The anodic coupling of an enol ether to an oxygen nucleophile has been used as a key step in the total synthesis of (+)-nemorensic acid. The anodic cyclization reaction allows for a reversal in the way the tetrahydrofuran ring of the natural product is normally assembled and thus enables construction of the ring in a highly stereoselective fashion.
Simple versus optimal mechanisms

The monopolist's theory of optimal single-item auctions for agents with independent private values can be summarized by two statements. The first is from Myerson [8]: the optimal auction is Vickrey with a reserve price. The second is from Bulow and Klemperer [1]: it is better to recruit one more bidder and run the Vickrey auction than to run the optimal auction. These results hold for single-item auctions under the assumption that the agents' valuations are independently and identically drawn from a distribution that satisfies a natural (and prevalent) regularity condition.These fundamental guarantees for the Vickrey auction fail to hold in general single-parameter agent mechanism design problems. We give precise (and weak) conditions under which approximate analogs of these two results hold, thereby demonstrating that simple mechanisms remain almost optimal in quite general single-parameter agent settings.
The “probability of recession”: Evaluating probabilistic and non-probabilistic forecasts from probit models of U.S. recessions

This letter evaluates forecasts from probit models that use the slope of the yield curve to forecast recessions. These models give reliable non-probabilistic warnings of recessions, but the estimated probabilities do not match the conditional frequency of recession months.
Real-time Remote Identification and Verification of Objects Using Optical ID Tags

We describe active and passive optical identification tags and readers for remote identification and verification of objects. These include a wavelength-hopped laser encoding and decoding system, and a retroreflective optically phase-modulated ID tag and reader.
Successful U.S. Entrepreneurs: Identifying Ethical Decision-making and Social Responsibility Behaviors

This two-part study analyzed some of the ethical choices made by founding entrepreneurs during the creation and development of their ventures in order to identify the areas in which founding entrepreneurs must make decisions related to ethics or social responsibility during venture creation and development. Content analysis was used to identify decisions with ethical components and/or implications from in-depth interviews with 10 successful business founders. The research for part one of the study was guided by the following research question: In what areas must entrepreneurs make decisions with ethical and/or social responsibility implications during new venture creation and development? The authors identified four distinct categories of decisions where ethical or social responsibility components exist: (1) individual entrepreneurial values-related decisions, (2) organizational culture/employee well-being decisions, (3) customer satisfaction and quality decisions, and (4) external accountability decisions. In the second part of the study, the decisions identified in part one were analyzed using a framework derived from prior research in ethics. This framework was developed from the work of Kant (1964) who theorized about human morals and Rawls (1971) who developed theories about justice. Part two of the study was guided by the following research questions: Do entrepreneurs have values and ethics similar to those held by society in general? If they don’t, how do their values and ethics differ? The comparison revealed that the ethics and/or values that the entrepreneurs either explicitly or implicitly acknowledged were in fact similar to those of society in general.
Lie symmetries of the Chow group of a Jacobian and the tautological subring

Let $J$ be the Jacobian of a smooth projective curve. We define a natural action of the Lie algebra of polynomial Hamiltonian vector fields on the plane, vanishing at the origin, on the Chow group of $J$ with rational coefficients. Using this action we obtain some relations between tautological cycles on $J$.
Efficient regioselective synthesis of enantiomerically pure 4-hydroxymethyl-Δ2-thiazoline

Abstract Optically pure 2-unsubstituted-4-hydroxymethyl-Δ2-thiazoline was prepared by regioselective cyclization of (R)-3-hydroxy-2-aminopropanethiol.
External-Memory Multimaps

Many data structures support dictionaries, also known as maps or associative arrays, which store and manage a set of key-value pairs. A multimap is generalization that allows multiple values to be associated with the same key. For example, the inverted file data structure that is used prevalently in the infrastructure supporting search engines is a type of multimap, where words are used as keys and document pointers are used as values. We study the multimap abstract data type and how it can be implemented efficiently online in external memory frameworks, with constant expected I/O performance. The key technique used to achieve our results is a combination of cuckoo hashing using buckets that hold multiple items with a multiqueue implementation to cope with varying numbers of values per key. Our external-memory results are for the standard two-level memory model.
Global regularity for a logarithmically supercritical defocusing nonlinear wave equation for spherically symmetric data

We establish global regularity for the logarithmically energy-supercritical wave equation □u = u5log(2 + u2) in three spatial dimensions for spherically symmetric initial data, by modifying an argument of Ginibre, Soffer and Velo for the energy-critical equation. This example demonstrates that critical regularity arguments can penetrate very slightly into the supercritical regime.
A Computational and Experimental Investigation of the Human Thermal Plume

The behavior of the buoyant plume of air shed by a human being in an indoor environment is important to room ventilation requirements, airborne disease spread, air pollution control, indoor air quality, and the thermal comfort of building occupants. It also becomes a critical factor in special environments like surgery rooms and clean-rooms. Of the previous human thermal plume studies, few have used actual human volunteers, made quantitative plume velocity measurements, or considered thermal stratification of the environment. Here, a study of the human thermal plume in a standard room environment, including moderate thermal stratification, is presented. We characterize the velocity field around a human volunteer in a temperature-stratified room using particle image velocimetry (PIV). These results are then compared to those obtained from a steady three-dimensional computational fluid dynamics (CFD) solution of the Reynolds-averaged Navier-Stokes equations (RANS) using the RNG k‐e two-equation turbulence model. Although the CFD simulation employs a highly simplified model of the human form, it nonetheless compares quite well with the PIV data in terms of the plume centerline velocity distribution, velocity profiles, and flow rates. The effect of thermal room stratification on the human plume is examined by comparing the stratified results with those of an additional CFD plume simulation in a uniform-temperature room. The resulting centerline velocity distribution and plume flow rates are presented. The reduction in plume buoyancy produced by room temperature stratification has a significant effect on plume behavior.
Electronic structure of underdoped cuprates

Abstract We consider a two-dimensional Fermi-liquid coupled to low-energy commensurate spin fluctuations. At small coupling, the hole Fermi surface is large and centered around Q = ( π , π ). We show that as the coupling increases, the shape of the quasiparticle Fermi surface and the spin-fermion vertex undergo a substantial evolution. At strong couplings, g ⪢ ω 0 , where ω 0 is the upper cutoff in the spin susceptibility, the hole Fermi surface consists of small pockets centered at ( ± π 2 , ± π 2 ). The full spin-fermion vertex is much smaller than the bare one, and scales nearly linearly with ¦q − Q¦ , where q is the momentum of the susceptibility. At intermediate couplings, there exist both, a large hole Fermi surface centered at (π,π), and four hole pockets, but the quasiparticle residue is small everywhere except for the pieces of the pockets which face the origin of the Brillouin zone. The relevance of these results for recent photoemission experiments in YBCO and Bi2212 systems is discussed.
A PRACTICAL PREPARATION OF L-ASPARTYL-D-2-AMINOBUTYRIC ACID (S)-α-PHENYLPROPYLAMIDE, A NEW HIGH-POTENCY SWEETENER

(1997). A PRACTICAL PREPARATION OF L-ASPARTYL-D-2-AMINOBUTYRIC ACID (S)-α-PHENYLPROPYLAMIDE, A NEW HIGH-POTENCY SWEETENER. Organic Preparations and Procedures International: Vol. 29, No. 2, pp. 177-183.
Palladium-catalyzed asymmetric diene cyclization/hydrosilylation employing functionalized silanes and disiloxanes.

Pentasubstituted disiloxanes and silanes of the form HSiMe2CHxPh3-x (x = 1 or 2) reacted with dimethyl diallylmalonate (1) and other functionalized 1,6-dienes in the presence of a catalytic 1:1 mixture of (N−N)Pd(Me)Cl [N−N = (R)-(+)-4-isopropyl-2-(2-pyridinyl)-2-oxazoline] [(R)-2] and NaBAr4 [Ar = 3,5-C6H3(CF3)2] to form the corresponding silylated cyclopentanes in good yield with high diastereoselectivity. The enantioselectivity of cyclization/hydrosilylation of 1 with disiloxanes and functionalized silanes at −20 °C increased in the following order: HSiMe2OSiMe3 (75% ee) < HSiMe2OSiMe2-t-Bu (80% ee) < HSi(i-Pr)2OSiMe3 (86% ee) = HSiMe2Bn (86% ee) < HSiMe2OSi(i-Pr)3 (89% ee) < HSiMe2OSiPh2-t-Bu (91% ee) < HSiMe2CHPh2 (93% ee). Silylated cyclopentanes derived from HSiMe2OSiMe3 were oxidized with excess KF and peracetic acid at room temperature for 48 h to form the corresponding hydroxymethylcyclopentanes in good yield (82−95%). Silylated cyclopentanes derived from HSiMe2OSiPh2t-Bu were oxidized with a m...
Micropatterned polymer substrates control alignment of proliferating Schwann cells to direct neuronal regeneration

Abstract Microcontact printed polymeric substrates were evaluated for their ability to control Schwann cell attachment and direct proliferation, as Schwann cell guidance is a crucial factor in directing peripheral nerve regeneration. Elastomeric stamps of poly(dimethylsiloxane) were “inked” with laminin, a permissive protein for Schwann cell adhesion, and stamped onto poly(methyl methacrylate) substrates to create patterns of lines and intervals varying from 10 to 50 μm wide. Schwann cells were seeded onto the substrates in serum-free media. After 4 h, media was replaced with serum-containing growth media and changed daily thereafter. The addition of growth media to stimulate proliferation initially caused some loss in cell orientation relative to the laminin pattern, but when monolayer formation was complete, a high degree of cell orientation was observed. As both cell–cell contacts and surface coverage were maximized, the Schwann cells achieved an even higher order of orientation than observed during the early stages of proliferation. Significantly, smaller pattern widths increased the degree of orientation, regardless of interval width. Our results indicate that patterned polymeric substrates may enhance peripheral nerve regeneration by creating a highly ordered Schwann cell matrix for guidance of neurons.
A note on knowledge-based programs and specifications

Knowledge-based program are programs with explicit tests for knowledge. They have been used successfully in a number of applications. Sanders has pointed out what seem to be a counterintuitive property of knowledge-based programs. Roughly speaking, they do not satisfy a certain monotonicity property, while standard programs (ones without tests for knowledge) do. It is shown that there are two ways of defining the monotonicity property, which agree for standard programs. Knowledge-based programs satisfy the first, but do not satisfy the second. It is further argued by example that the fact that they do not satisfy the second is actually a feature, not a problem. Moreover, once we allow the more general class of knowledge-based specifications, standard programs do not satisfy the monotonicity property either.
Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests

The simplest form of a sufficiently realistic description of the fracture of concrete as well as some other quasibrittle materials is a bilinear softening stress-separation law (or an analogous bilinear law for a crack band). This law is characterized by four independent material parameters: the tensile strength, $$f'_t$$ , the stress $$\sigma _k$$ at the change of slope, and two independent fracture energies—the initial one, $$G_f$$ and the total one, $$G_F$$ . Recently it was shown that all of these four parameters can be unambiguously identified neither from the standard size effects tests, nor from the tests of complete load-deflection curve of specimens of one size. A combination of both types of test is required, and is here shown to be sufficient to identify all the four parameters. This is made possible by the recent data from a comprehensive test program including tests of both types made with one and the same concrete. These data include Types 1 and 2 size effects of a rather broad size range (1:12.5), with notch depths varying from 0 to 30 % of cross section depth. Thanks to using identically cured specimens cast from one batch of one concrete, these tests have minimum scatter. While the size effect and notch length effect were examined in a separate study, this paper deals with inverse finite element analysis of these comprehensive test data. Using the crack band approach, it is demonstrated: (1) that the bilinear cohesive crack model can provide an excellent fit of these comprehensive data through their entire range, (2) that the $$G_f$$ value obtained agrees with that obtained by fitting the size effect law to the data for any relative notch depth deeper than 15 % of the cross section (as required by RILEM 1990 Recommendation), (3) that the $$G_F$$ value agrees with that obtained by the work-of-fracture method (based on RILEM 1985 Recommendation), and (4) that the data through their entire range cannot be fitted with linear or exponential softening laws.
Generalized Characteristics of Communication, Sensing, and Navigation Satellite Systems

A generalized framework has been developed for classifying space system architectures and their characteristics for any mission in communications, sensing, or navigation. For each of these applications, the overall mission objective is to transfer informationbetween remote locations and to do so effectively and economically.Consequently, satellite systems can be represented as informationtransfer networks, serving origin–destination informationmarkets. Their capabilities are characterized by four quality-of-service parameters that relate to the isolation, rate, integrity, and availability of the information transferred. This generalized approach has led to signi cant conclusions in a variety of applications and has allowed a comprehensive characterization of satellite systems in general. Based on the argumentspresented, deduced from organized, qualitativeanalysis, it wouldappear that the potential offered by distributed satellite systems is very great.
Spectroscopy of UO2Cl42- in Basic Aluminum Chloride−1-Ethyl-3-methylimidazolium Chloride

The optical absorption, emission, FT Raman, one-photon excitation, two-photon excitation, and luminescence lifetime measurements are reported for UO2Cl42- in 40:60 AlCl3−EMIC (where EMIC ≡ 1-ethyl-...
Inward-looking policies, institutions, autocrats, and economic growth in Latin America: An empirical exploration *

This paper explores the institutionaldeterminants of economic growth in LatinAmerica by taking advantage of recentempirical research that employs subjectiveand objective measures to test for apossible “Northian” explanation that linksinstitutional quality and economic growth.We explore a simple framework that may helpbetter understand the policymakers’ choicesand persistence regarding inward-lookingpolicies that were pursued between the1930s and the 1980s by arguing that in theLatin American case Olson’s (1982) idea ofencompassing interest should be expanded tocover not only the economic stakes of powerholders, but in particular, their psychicincome which includes their politicalstakes, along the lines of recent work byRobinson (1997), Coyne (2002), andothers.
String theory near a conifold singularity

Abstract We demonstrate that type II string theory compactified on a singular Calabi-Yau manifold is related to c = 1 string theory compactified at the self-dual radius. We establish this result in two ways. First we show that complex structure deformations of the conifold correspond, on the mirror manifold, to the problem of maps from two dimensional surfaces to S2. Using two dimensional QCD we show that this problem is identical to c = 1 string theory. We then give an alternative derivation of this correspondence by mapping the theory of complex structure deformations of the conifold to Chern-Simons theory on S3. These results, in conjunction with similar results obtained for the compactification of the heterotic string on K 3 ×T 2 , provide strong evidence in favour of S-duality between type II strings compactified on a Calabi-Yau manifold and the heterotic string on K3 × T2.
The future of hard and electromagnetic probes at RHIC

Potential near- and long-term physics opportunities with jets, heavy flavors and electromagnetic probes at RHIC are presented. Much new physics remains to be unveiled using these probes, due to their sensitivity to the initial high density stage of RHIC collisions, when quark-gluon plasma (QGP) formation is expected. Additional physics will include addressing deconfinement, chiral symmetry restoration, properties of the strongly-coupled QGP and a possible weakly-interacting QGP, color glass condensate in the initial state, and hadronization. To fully realize the physics prospects of the RHIC energy regime, new detector components must be added to existing experiments, the RHIC machine luminosity upgraded, and a possible new detector with significantly extended coverage and capabilities added.
Strategy for the synthesis of unsymmetrical N-substituted polyazamacrocycles

Abstract A convergent route is described for the preparation of unsymmetrical N-substituted polyammonium macrocycles that is potentially applicable for the synthesis of a wide variety of macrocycles of differing ring size and heteroatom substitution.
Real-Time Model-Based Vision System For Object Acquisition And Tracking

A useful space telerobot for on-orbit assembly, maintenance, and repair tasks must have a sensing and perception subsystem which can provide the locations, orientations, and velocities of all relevant objects in the work environment. This function must be accomplished with sufficient speed and accuracy to permit effective grappling and manipulation. Appropriate symbolic names must be attached to each object for use by higher-level planning algorithms. Sensor data and inferences must be presented to the remote human operator in a way that is both comprehensible in ensuring safe autonomous operation and useful for direct teleoperation. Research at JPL toward these objectives is described.
One-pot synthesis of chiral azetidines from chloroaldehyde and chiral amines

A variety of chiral azetidinepiperidines have been synthesized utilizing an expedient one-pot union of piperidine chloroaldehyde with chiral amines. This two step one-pot procedure provides access to an interesting set of compounds that retain the chiral purity of the starting chiral amine.
Reconstruction Using Witness Complexes

We present a novel reconstruction algorithm that, given an input point set sampled from an object S, builds a one-parameter family of complexes that approximate S at different scales. At a high level, our method is very similar in spirit to Chew’s surface meshing algorithm, with one notable difference though: the restricted Delaunay triangulation is replaced by the witness complex, which makes our algorithm applicable in any metric space. To prove its correctness on curves and surfaces, we highlight the relationship between the witness complex and the restricted Delaunay triangulation in 2d and in 3d. Specifically, we prove that both complexes are equal in 2d and closely related in 3d, under some mild sampling assumptions.
Euclidean calculation of feature points of a rotating satellite: A daisy-chaining approach

The occlusion of feature points and/or feature points leaving the field of view of a camera is a significant practical problem that can lead to degraded performance or instability of visual servo control and vision-based estimation algorithms. By assuming that one known Euclidean distance between two feature points in an initial view is available, homography relationships and image geometry are used in this paper to determine the Euclidean coordinates of feature points in the field of view. A new daisy-chaining method is then used to relate the position and orientation of a plane defined by the feature points to other feature-point planes that are rigidly connected. Through these relationships, the Euclidean coordinates of the original feature points can be tracked even as they leave the field of view. This objective is motivated by the desire to track the Euclidean coordinates of feature points on one face of a satellite as it continually rotates and feature points become self-occluded. A numerical simulation is included to demonstrate that the Euclidean coordinates can be tracked even when they leave the field of view. However, the results indicate the need for a method to reconcile any accumulated error when the feature points return to the field of view.
The acetylcholine receptor: progress report.

Publisher Summary This chapter presents a progress report on the acetylcholine receptor (ACHR). All approaches to the ACHR begin with the response of cells to ACH and the modification of this response. The binding properties of the ACHR are inferred from the variation of the response as a function of the concentration of ACH and of its congeners. The occupation of binding sites is usually taken to be determined by the Langmuir adsorption isotherm, formally equivalent to the Michaelis–Menten equation. The response to agonists is assumed to increase with increasing occupation. If the response was linearly proportional to occupation, then the equilibrium dissociation constant for an activator–ACHR complex would be equal to the concentration of activator eliciting a half-maximal response. One approach to the structure of the binding site is to model it to accommodate potent activators and competitive inhibitors. Those aspects of the structure of these ligands that confer potency are determined and the corresponding structure is inferred for the site. Hydrophilic substitutents, as in choline or in p-carboxyphenyltrimethylammonium, apparently strongly inhibit binding, and such compounds are neither activators nor inhibitors. From these results, it appears that there is a subsite of hydrophobic interaction about 1 nm from the negative subsite.
A Coarse-Grained Model Based on Morse Potential for Water and N-Alkanes

In order to extend the time and distance scales of molecular dynamics simulations, it is essential to create accurate coarse-grained force fields, in which each particle contains several atoms. Coarse-grained force fields that utilize the Lennard-Jones potential form for pair-wise non-bonded interactions have been shown to suffer from serious inaccuracy, notably with respect to describing the behavior of water. In this paper we describe a coarse-grained force field for water, in which each particle contains four water molecules, based on the Morse potential form. By molecular dynamics simulations we show that our CSJ force field closely replicates important water properties. We also describe a Morse potential force field for alkanes and a simulation method for alkanes in which individual particles may have variable size, providing flexibility in constructing complex molecules comprised partly or solely of alkane groups. We find that in addition to being more accurate, the Morse potential also provides the ability to take larger time steps than the Lennard-Jones, because the short distance repulsion potential profile is less steep. The Morse potential is implemented in Gromacs, using a rapid table look-up capability available in that simulation package. The table look-up is about 20% slower per time step than the standard Lennard-Jones, but is more than compensated for by the longer time step possible, so that overall simulation times are shorter when using the Morse potential. We suggest that the Morse potential form should be considered as an alternative for the Lennard-Jones form for coarse-grained molecular dynamics simulations. We are working on coarse-grained force fields for amphipathic molecules and for ions, and will provide a progress report on that work in this presentation.
Quasilinear equations with source terms on Carnot groups

In this paper we give necessary and sufficient conditions for the existence of solutions to quasilinear equations of Lane–Emden type with measure data on a Carnot group G of arbitrary step. The quasilinear part involves operators of the p-Laplacian type ∆G, p , 1 < p < ∞. These results are based on new a priori estimates of solutions in terms of nonlinear potentials of Th. Wolff’s type. As a consequence, we characterize completely removable singularities, and prove a Liouville type theorem for supersolutions of quasilinear equations with source terms which has been known only for equations involving the sub-Laplacian (p = 2) on the Heisenberg group.
Representation theory of symmetric groups and related Hecke algebras

We survey some fundamental trends in representation theory of symmetric groups and related objects which became apparent in the last fifteen years. The emphasis is on connections with Lie theory via categorification. We present results on branching rules and crystal graphs, decomposition numbers and canonical bases, graded representation theory, connections with cyclotomic and affine Hecke algebras, Khovanov-Lauda-Rouquier algebras, category O, W -algebras, . . .
Triethylborane-Initiated Radical Chain Fluorination: A Synthetic Method Derived from Mechanistic Insight

We offer a mild, metal-free sp3 C–H fluorination alternative using Selectfluor and a substoichiometric amount of triethylborane—an established radical initiator in the presence of O2. This radical-chain-based synthetic method is particularly noteworthy as an offspring of the insight gained from a mechanistic study of copper-promoted aliphatic fluorination, constructively turning O2 from an enemy to an ally. Furthermore, BEt3/O2 is a preferred initiator in industrial processes, as it is economical, is low in toxicity, and lends way to easier workup.