cssi/SciSciGPT-SciSciNet huggingface dataset:
Unprecedented stereoselectivity in the Staudinger reaction with polycyclic aromatic imines

Cycloaddition of imines derived from polycyclic aromatic amines with acid chloride (or equivalent) in the presence of triethylamine at −78°C to room temperature unexpectedly produced trans-β-lactams.
On the Robustness of Equilibrium Refinements

Abstract The philosophy of equilibrium refinements is that the analyst, if he knows things about the structure of the game, can reject some Nash equilibria as unreasonable. The word “know” in the preceding sentence deserves special emphasis. If in a fixed game the analyst can reject a particular equilibrium outcome, but he cannot do so for games arbitrarily “close by,” then he may have second thoughts about rejecting the outcome. We consider several notions of distance between games, and we characterize their implications for the robustness of equilibrium refinements.
The homotopy operator method for symbolic integration by parts and inversion of divergences with applications

Using standard calculus, explicit formulas for one-, two- and three-dimensional homotopy operators are presented. A derivation of the one-dimensional homotopy operator is given. A similar methodology can be used to derive the multi-dimensional versions. The calculus-based formulas for the homotopy operators are easy to implement in computer algebra systems such as Mathematica, Maple and REDUCE. Several examples illustrate the use, scope and limitations of the homotopy operators. The homotopy operator can be applied to the symbolic computation of conservation laws of nonlinear partial differential equations (PDEs). Conservation laws provide insight into the physical and mathematical properties of the PDE. For instance, the existence of infinitely many conservation laws establishes the complete integrability of a nonlinear PDE.
p-Suffix sorting as arithmetic coding

The challenge of direct parameterized suffix sorting (p-suffix sorting) for a parameterized string (p-string), say T of length-n, is the dynamic nature of the n parameterized suffixes (p-suffixes) of T. In this work, we propose transformative approaches to direct p-suffix sorting by generating and sorting lexicographically numeric fingerprints and arithmetic codes that correspond to individual p-suffixes. Our algorithm to p-suffix sort via fingerprints is the first theoretical linear time algorithm for p-suffix sorting for non-binary parameter alphabets, which assumes that, in practice, all codes are within the range of an integral data type. We eliminate the key problems of fingerprints by introducing an algorithm that exploits the ordering of arithmetic codes to sort p-suffixes in linear time on average. The arithmetic coding approach is further extended to handle p-strings in the worst case. This algorithm is the first direct p-suffix sorting approach in theory to execute in o(n^2) time in the worst case, which improves on the best known theoretical result on this problem that sorts p-suffixes based on p-suffix classifications in O(n^2) time. We show that, based on the algorithmic parameters and the input data, our algorithm does indeed execute in linear time in various cases, which is confirmed with experimental results.
Characterization of Healable Polymers

Materials with an internal mechanism for damage repair would be valuable in isolated environments where access is difficult or impossible. Current work is focused on characterizing neat polymers with reformable cross-linking bonds. These bonds are thermally reversible, the result of a Diels-Alder cycloaddition between furan and maleimide monomers. Candidate polymers are examined using modulated differential scanning calorimetry (DSC) to confirm the presence of reversible bonding. One polymer, 2MEP3FT, was expected to have these bonds, but none were observed. A second polymer, 2MEP4FS, with a modified furan monomer does exhibit reversible bonding. Further DSC testing and dynamic mechanical thermal analyses (DMA) are conducted to determine material properties such as glass transition temperature, storage modulus and quality of the polymerization. Healing efficiency is established using the double cleavage drilled compression (DCDC) fracture test. A column of material with a central hole is subjected to axial compression, driving cracks up and down the sample. After unloading, the cracks are healed, and the sample is retested. Comparing the results gives a quantitative evaluation of healing.
Treatment selection for coronary artery disease: The collision of a belief system with evidence.

Development of interventional therapy for coronary artery disease (CAD) has unquestionably improved and prolonged the lives of millions, but the complex manifestations and presentations of the disease have confounded easy decision making to develop “the best treatment” option for each patient. Two important papers, recently published, support coronary artery bypass grafting (CABG) as the treatment of choice for patients with advanced CAD (3-vessel disease or left main coronary disease) compared with percutaneous coronary intervention (PCI). The Synergy between PCI with Taxus and Cardiac Surgery (SYNTAX) trial [1] demonstrated a significant reduction in the composite rate of major adverse cardiovascular event (MACE) end point, defined as mortality, myocardial infarction, stroke, or reintervention, for CABG compared with PCI. The “Appropriateness Criteria for Coronary Revascularization,” sponsored by the American College of Cardiology Foundation, assembled experts to create 180 different clinical vignettes to represent a cross-section of contemporary practice as encountered by working cardiologists and surgeons [2, 3]. For 3-vessel disease, CABG was rated appropriate, and PCI rated uncertain. For left main coronary disease, CABG was rated appropriate, and PCI was rated inappropriate. Despite these findings, it is apparent that their translation into practice is being heavily influenced by various stakeholders whose belief systems are unfulfilled by the evidence. The purpose of this editorial is to clarify the body of evidence as it exists today so that all stakeholders are held accountable to the primary stakeholders, our patients. This is only reasonable, because 3-three vessel CAD afflicts 23% of patients found to have significant coronary disease at diagnostic cardiac catheterization (unpublished data from 10,149 patients in the Duke Cardiovascular Disease Databank, 2000 to 2008). Long-term follow-up of patients who received medical treatment shows survival at 5, 10, and 15 years of only 61%, 38%, and 22%, respectively (Fig 1). When patients were treated by PCI or CABG, survival at 5, 10, and 15 years significantly improved to 76%, 54%, and 34%, respectively (Fig 1). Logically, therefore, preservation of life should be the predominant component framing the evidence in recommending PCI or CABG for these patients. The SYNTAX Trial
Vented Compression Molding

A new process, vented compression molding, is developed for molding low density particulates, such as ablative materials used in the Space Shuttle. This process is a modification of standard compression molding that uses a perforated surface as the molding surface. An excess of material is used to fill the mold cavity and this material is forced through the openings in the surface of the mold as the mold closes. This process creates frictional forces, which can be determined approximately by Mohr-Coulomb yield criterion, generating the pressure that compacts the material. The pressure in the mold is shown to be governed by the geometry of the openings and the mechanical properties of the particulate, and not by the displacement or the volume of the mold. It is determined that this uncoupling of the pressure-displacement relationship allows uniform material distribution and compaction without requiring large-scale flow of the particulates.
Rotordynamic Force Prediction of Centrifugal Compressor Impellers Using Computational Fluid Dynamics

The energy industry depends on centrifugal compressors to produce, process, reinject, and transport many different gases. Centrifugal compressors use one or more impellers to impart momentum to the flowing gas and, thereby, produce an increase in pressure through diffusion. As the operating pressure in a compressor increases, the fluid-rotor interaction at the seals and impellers become more important. Also, the new generation of megascale liquefied natural gas compressors is dependent on accurate assessment of these forces. The aerodynamic forces and cross-coupled stiffness from the impellers cannot be accurately predicted with traditional methods and must be estimated with semi-empirical formulations. The result of these inaccuracies is a potential for compressor designs that can experience unexpected, dangerous, and damaging instabilities and sub-synchronous vibrations. The current investigation is intended to advance the state of the art to achieve an improved, physics-based method of predicted aerodynamic destabilizing cross-coupling forces on centrifugal compressor impellers using computational fluid dynamics (CFD). CFD was employed in this study to predict the impeller-fluid interaction forces, which gives rise to the aerodynamic cross coupling. The procedure utilized in this study was developed by Moore and Palazzolo (2002, "Rotordynamic Force Prediction of Centrifugal Impeller Shroud Passages Using Computational Fluid Dynamic Techniques With Combined Primary Secondary Flow Model, " ASME J. Eng. Gas Turbines Power, 123, pp. 910―918), which applied the method to liquid pump impellers. Their results showed good correlation to test data. Unfortunately, no such data exist for centrifugal compressors. Therefore, in order to validate the present model, comparisons will be made to predict the instability of an industrial centrifugal compressor. A parametric CFD study is then presented leading to a new analytical expression for predicting the cross-coupled stiffness for centrifugal impellers.
The influence of sensor and flight parameters on texture in radar images

Texture is known to be Important in the analysis of radar images for geologic applications. It has previously been shown that texture features derived from the grey-level co-occurrence matrix (GLCM) can be used to separate large-scale texture in radar images. Here the influence of sensor parameters, specifically the spatial and radiometric resolution and flight parameters, i.e., the orientation of the surface structure relative to the sensor, on the ability to classify texture based on the GLCM features is investigated. It was found that changing these sensor and flight parameters greatly affects the usefulness of the GLCM for classifying texture on radar images.
Bayesian general equilibrium

I introduce a general equilibrium model of non-optimizing agents that respond to aggregate variables (prices and the average demand profile of agent types) by putting a “prior” on their demand. An interim equilibrium is defined by the posterior demand distribution of agent types conditional on market clearing. A Bayesian general equilibrium (BGE) is an interim equilibrium such that aggregate variables are correctly anticipated. Under weak conditions, I prove the existence and the informational efficiency of BGE. I discuss the conditions under which the set of Bayesian and Walrasian equilibria coincide and show that the Walrasian equilibrium arises from a large class of non-optimizing behavior.
Gorenstein projective dimension for complexes

We define and study a notion of Gorenstein projective dimension for complexes of left modules over associative rings. For complexes of finite Gorenstein projective dimension we define and study a Tate cohomology theory. Tate cohomology groups have a natural transformation to classical Ext groups. In the case of module arguments, we show that these maps fit into a long exact sequence, where every third term is a relative cohomology group defined for left modules of finite Gorenstein projective dimension.
Betti tables of reducible algebraic curves

We study the Betti tables of reducible algebraic curves with a focus on connected line arrangements and provide a general formula for computing the quadratic strand of the Betti table for line arrangements that satisfy certain hypotheses. We also give explicit formulas for the entries of the Betti tables for all curves of genus zero and one. Last, we give formulas for the graded Betti numbers for a class of curves of higher genus.
Dynamics of nonequilibrium deposition

Abstract In this work we survey selected theoretical developments for models of deposition of extended particles, with and without surface diffusion, on linear and planar substrates, of interest in colloid, polymer, and certain biological systems.
On the free convolution with a free multiplicative analogue of the normal distribution

We obtain a formula for the density of the free convolution of an arbitrary probability measure on the unit circle of \(\mathbb {C}\) with the free multiplicative analogues of the normal distribution on the unit circle. This description relies on a characterization of the image of the unit disc under the subordination function, which also allows us to prove some regularity properties of the measures obtained in this way. As an application, we give a new proof for Biane’s classic result on the densities of the free multiplicative analogue of the normal distributions. We obtain analogue results for probability measures on \(\mathbb {R}^+\). Finally, we describe the density of the free multiplicative analogue of the normal distributions as an example and prove unimodality and some symmetry properties of these measures.
Deriving the Quasar Luminosity Function from Accretion-Disk Instabilities

We have derived the quasar luminosity function assuming that the quasar activity is driven by a thermal-viscous unstable accretion disk around a supermassive black hole. The instabilities produce large amplitude, long-term variability of a single source. We take a light curve of a single source and calculate the luminosity function from the fraction of time it spends at each luminosity. Convolving this with an assumed mass distribution we were able to fit well the observed optical luminosity function of quasars at four redshifts. As a result we obtain the evolution of the mass distribution between redshifts 2.5 and 0.5. The main conclusions are as follows: (1) the quasar long-term variability due to the disk thermal-viscous instabilities provides a natural explanation for the observed quasar luminosity function; (2) the peak of the mass function evolves toward lower black hole masses at lower redshifts by a factor ~10; (3) the number of high-mass sources declines rapidly, so low-mass sources become dominant at lower redshift; (4) outbursts of activity appear as long as the matter is supplied to the accretion disk; (5) since the time-averaged accretion rate is low, the remnant sources (or sources in the low activity phase) do not grow into very massive black holes; and (6) a continuous fuel supply at a relatively low accretion rate (~0.01-0.1 ${u{M}{"705F}}$ -->Edd) for each single source is required over the lifetime of the entire quasar population.
Crosshole seismoelectric measurements in borehole models with fractures

Laboratory experiments are performed in crossborehole models with fractures to investigate seismoelectric conversions in the fractures. Using an electrode in a borehole, we measure the electric field induced by an acoustic wave, and we investigate the relationship between the electric signal and the fracture aperture using ultrasonic fracture borehole models. The experimental results confirm that a radiating electromagnetic (EM) wave is induced by a guide wave at a fracture between an acoustic source and electric receiver boreholes. The position of a vertical or inclined fracture between two boreholes can be determined using the arrival times of the EM wave and the formation velocity by placing the acoustic source at a different depth and recording electric signals with real or synthetic arrays of acoustic and electric receivers in the second borehole. Crosshole seismoelectric measurements might be a technique for investigating fractures between boreholes more directly than traditional acoustic measurements.
Chromatin remodeling by the CHD7 protein is impaired by mutations that cause human developmental disorders

Mutations in the CHD7 gene cause human developmental disorders including CHARGE syndrome. Genetic studies in model organisms have further established CHD7 as a central regulator of vertebrate development. Functional analysis of the CHD7 protein has been hampered by its large size. We used a dual-tag system to purify intact recombinant CHD7 protein and found that it is an ATP-dependent nucleosome remodeling factor. Biochemical analyses indicate that CHD7 has characteristics distinct from SWI/SNF- and ISWI-type remodelers. Further investigations show that CHD7 patient mutations have consequences that range from subtle to complete inactivation of remodeling activity, and that mutations leading to protein truncations upstream of amino acid 1899 of CHD7 are likely to cause a hypomorphic phenotype for remodeling. We propose that nucleosome remodeling is a key function for CHD7 during developmental processes and provide a molecular basis for predicting the impact of disease mutations on that function.
An Effective Field Theory Approach to Color Superconductivity at High Quark Density

Abstract We investigate the Fermi Liquid theory of high density QCD. Using the renormalization group (RG), we determine the behavior of effective fermion interactions near the Fermi surface. At sufficiently high densities the matching between the Fermi Liquid theory and QCD can be accomplished in perturbation theory and a reliable calculation of Cooper pair formation performed, modulo the existence of screening masses for the gluon. The presence of a chemical potential leads to different RG flows for sub-components of the effective interactions which would ordinarily be linked by Lorentz invariance. We also study instanton-induced operators and find that near the Fermi surface they are likely to be subdominant relative to operators induced by perturbative gluon exchange. We discuss the implications of our results for the phase structure of QCD at finite baryon density and temperature.
Physical limitations on quantum nonlocality in the detection of photons emitted from positron-electron annihilation

Recent experimental measurements of the time interval between detection of the two photons emitted in positron-electron annihilation have indicated that collapse of the spatial part of the photon's wave function, due to detection of the other photon, does not occur. Although quantum nonlocality actually occurs in photons produced through parametric down-conversion, the recent experiments give strong evidence against measurement-induced instantaneous spatial localization of high-energy $\ensuremath{\gamma}$ photons. A quantum-mechanical analysis of the Einstein-Podolsky-Rosen problem is presented, which may help to explain the observed differences between photons produced through parametric down-conversion and photons produced through positron-electron annihilation. The results are found to concur with the recent experiments involving $\ensuremath{\gamma}$ photons.
EGF IN COMBINATION WITH DEPOLARIZATION OR CAMP PRODUCES MORPHOLOGICAL BUT NOT PHYSIOLOGICAL DIFFERENTIATION IN PC12 CELLS

In response to nerve growth factor (NGF) or basic fibroblast growth factor (bFGF) receptor activated Ras/extracellular signal-regulated kinase (ERK) signaling, PC12 cells undergo a prototypical neuronal differentiation program, characterized by neurite extension and upregulation of voltage-gated ion channels. The epidermal growth factor (EGF) receptor also activates Ras/ERK signaling, but produces proliferation instead of differentiation. In the presence of depolarizing concentrations of KCl, however, EGF elicits neurite outgrowth through the synergistic actions of the Ras/ERK and cAMP signaling pathways. To assess if EGF and KCl/cAMP elicit the same suite of differentiation events as does NGF and bFGF, we used patch clamp recording to determine if EGF in the presence of KCl or a cAMP agonist also induced physiological differentiation as defined by upregulation of ion channels. Chronic NGF treatment of PC12 cell cultures elicited robust morphological differentiation, a threefold increase in mean calcium channel current density, and an eightfold increase in mean sodium channel current density. Sibling cultures chronically treated with EGF in the presence of high KCl or a cAMP agonist also displayed morphological differentiation, but had calcium channel current densities which were no larger than untreated, undifferentiated cells. Additionally, the increase in mean sodium channel current density induced by EGF in the presence of KCl or cAMP was no greater than the increase observed with EGF alone. Thus, although EGF in the presence of KCl or cAMP is sufficient to induce morphological differentiation as defined by neurite outgrowth, synergism of the Ras/ERK and cAMP/PKA signaling pathways is not sufficient to promote the fully physiologically differentiated PC12 phenotype.
Automated patient record summaries for health care auditing

At Northwestern University Medical Center, a computer printed summary report showing a patient's current condition appears to be especially useful in outpatient therapy. A printed summary report lends itself to the objectives of:1. Displaying a patient's current condition in an organized, up-to-date, accurate, and legible form.2. Auditing patient care in a uniform and consistent manner by processing the machine readable summary data.
Multiplicative Zagreb indices of k -trees

Let G be a graph with vertex set V ( G ) and edge set E ( G ) . The first generalized multiplicative Zagreb index of G is ? 1 , c ( G ) = ? v ? V ( G ) d ( v ) c , for a real number c 0 , and the second multiplicative Zagreb index is ? 2 ( G ) = ? u v ? E ( G ) d ( u ) d ( v ) , where d ( u ) , d ( v ) are the degrees of the vertices of u , v . The multiplicative Zagreb indices have been the focus of considerable research in computational chemistry dating back to Narumi and Katayama in 1980s. In this paper, we generalize Narumi-Katayama index and the first multiplicative index, where c = 1 , 2 , respectively, and extend the results of Gutman to the generalized tree, the k -tree, where the results of Gutman are for k = 1 . Additionally, we characterize the extremal graphs and determine the exact bounds of these indices of k -trees, which attain the lower and upper bounds.
Enantioselective reduction of esters: synthesis of optically active α-acetoxy ethers

Abstract An enantioselective reduction and acetylation of esters to α-acetoxy ethers is described. Reduction with a NaAlH 4 –ephedrine reagent followed by in situ acetylation gives 2 with good enantiomeric excess. This reaction is limited in scope, but it demonstrates that enantioselective reductions of esters are possible.
Organizing Space Shuttle parametric data for maintainability

A model of organization and management of Space Shuttle data is proposed. Shuttle avionics software is parametrically altered by a reconfiguration process for each flight. As the flight rate approaches an operational level, current methods of data management would become increasingly complex. An alternative method is introduced, using modularized standard data, and its implications for data collection, integration, validation, and reconfiguration processes are explored. Information modules are cataloged for later use, and may be combined in several levels for maintenance. For each flight, information modules can then be selected from the catalog at a high level. These concepts take advantage of the reusability of Space Shuttle information to reduce the cost of reconfiguration as flight experience increases.
Evidence on auditor risk-management strategies before and after The Private Securities Litigation Reform Act of 1995

Abstract This study provides evidence that auditors adopted risk-management policies in the early 1990s in order to reduce their exposure to legal liability. Specifically, there is evidence that their clienteles became less risky and evidence of more conservative auditor reporting policies by non-Big Six auditors (but not by Big Six auditors). The auditor's legal exposure was reduced under The Private Securities Litigation Reform Act of 1995, and there is evidence that risk-management policies were relaxed after 1994, resulting in riskier clienteles and less conservative reporting strategies for both Big Six and non-Big Six auditors. The study is important in documenting that alternative legal liability regimes can affect auditor incentives and behaviour. © City University of Hong Kong.
Dynamical Models of Elliptical Galaxies in z = 0.5 Clusters. I. Data-Model Comparison and Evolution of Galaxy Rotation

We present spatially resolved stellar rotation velocity and velocity dispersion profiles from Keck/LRIS absorption-line spectra for 25 galaxies, mostly visually classified ellipticals, in three clusters at z ≈ 0.5. We interpret the kinematical data and HST photometry using oblate axisymmetric two-integral f(E,Lz) dynamical models based on the Jeans equations. This yields good fits, provided that the seeing and observational characteristics are carefully modeled. The fits yield for each galaxy the dynamical mass-to-light ratio (M/L) and a measure of the galaxy rotation rate. Paper II addresses the implied M/L evolution. Here we study the rotation-rate evolution by comparison to a sample of local elliptical galaxies of similar present-day luminosity. The brightest galaxies in the sample all rotate too slowly to account for their flattening, as is also observed at z = 0. But the average rotation rate is higher at z ≈ 0.5 than locally. This may be due to a higher fraction of misclassified S0 galaxies (although this effect is insufficient to explain the observed strong evolution of the cluster S0 fraction with redshift). Alternatively, dry mergers between early-type galaxies may have decreased the average rotation rate over time. It is unclear whether such mergers are numerous enough in clusters to explain the observed trend quantitatively. Disk-disk mergers may affect the comparison through the so-called "progenitor bias," but this cannot explain the direction of the observed rotation-rate evolution. Additional samples are needed to constrain possible environmental dependencies and cosmic variance in galaxy rotation rates. Either way, studies of the internal stellar dynamics of distant galaxies provide a valuable new approach for exploring galaxy evolution.
Damage accumulation in ceramics during ion implantation

Abstract The damage structures of α-Al2O3 and α-SiC were examined as functions of ion implantation parameters using Rutherford backscattering-channeling, analytical electron microscopy, and Raman spectroscopy. Low temperatures or high fluences of cations favor formation of the amorphous state. At 300 K, the mass of the bombarding species has only a small effect on the residual damage state, but certain ion species appear to stabilize the damage microstructure and increase the rate of approach to the amorphous state. The type of chemical bonding present in the host lattice is an important factor in determining the residual damage state.
Elliptic quantum many-body problem and double affine Knizhnik-Zamolodchikov equation

The elliptic-matrix quantum Olshanetsky-Perelomov problem is introduced for arbitrary root systems by means of an elliptic version of the Dunkl operators. Its equivalence with the double affine generalization of the Knizhnik-Zamolodchikov equation (in the induced representations) is established.
Liquid‐Phase‐Assisted Transformation of Seeded γ‐Alumina

α-Al2O3-seeded, boehmite-derived γ-Al2O3 was transformed in the presence of V2O5, resulting in a 205°C decrease in the α-Al2O3 transformation temperature and a 74% reduction in the apparent activation energy for the γ- to α-Al2O3 transformation at temperatures greater than 850°C. These changes are attributed to the lowered energy barrier for nucleation by seeding and the lowered activation energy for material transport through the liquid relative to the unseeded, solid-state transformation. Growth of the transforming alumina yielded fine-grained α-Al2O3 particles which exhibited a highly faceted morphology. It is proposed that the combined control of both nucleation and growth during liquid-phase-assisted transformation provides a potentially powerful technique for tailoring powder characteristics in many material systems which undergo nucleation and growth processes.
An improved generalized inverse algorithm for linear inequalities and its applications

A great amount of research for the solution of linear inequalities has been undertaken in the past ten years. One of the reasons for this research is the development of linear separation approaches to pattern recognition and threshold logic problems. Both of these problems require the determination of a decision function or decision functions which, in the case of linear separation, involve a system of linear inequalities.
Chebyshev Polynomials on a System of Continua

The estimates of the uniform norm of the Chebyshev polynomial associated with a compact set $$K$$ consisting of a finite number of continua in the complex plane are established. These estimates are exact (up to a constant factor) in the case where the components of $$K$$ are either quasismooth (in the sense of Lavrentiev) arcs or closed Jordan domains bounded by a quasismooth curve.
Polar manifolds and actions

A group action is called polar if there exists an immersed submanifold (a section) which intersects all orbits orthogonally. We show how to construct a manifold admitting a polar group action by prescribing its isotropy groups along a fundamental domain in the section. This generalizes a classical construction for cohomogeneity-one manifolds.We give many examples showing the richness of this class of group actions and relate the topology of the section to the topology of the manifold.
Compatible dual-echo arteriovenography (CODEA) using an echo-specific K-space reordering scheme.

An improved dual-echo sequence magentic resonance (MR) imaging technique was developed to simultaneously acquire a time-of-flight MR angiogram (MRA) and a blood oxygenation level-dependent MR venogram (MRV) in a single MR acquisition at 3 T. MRA and MRV require conflicting scan conditions (e.g., excitation RF profile, flip angle, and spatial presaturation pulse) for their optimal image quality. This conflict was not well counterbalanced or reconciled in previous methods reported for simultaneous acquisition of MRA and MRV. In our dual-echo sequence method, an echo-specific K-space reordering scheme was used to uncouple the scan parameter requirements for MRA and MRV. The MRA and MRV vascular contrast was enhanced by maximally separating the K-space center regions acquired for the MRA and MRV, and by adjusting and applying scan parameters compatible between the MRA and MRV. As a preliminary result, we were able to acquire a simultaneous dual-echo MRA and MRV with image quality comparable to that of the conventional single-echo MRA and MRV that were acquired separately at two different sessions. Furthermore, integrated with tilted optimized nonsaturating excitation and multiple overlapping thin-slab acquisition techniques, our dual-echo MRA and MRV provided seamless vascular continuity over a large coverage volume of the brain anatomy. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.
TrAp: a tree approach for fingerprinting subclonal tumor composition

Revealing the clonal composition of a single tumor is essential for identifying cell subpopulations with metastatic potential in primary tumors or with resistance to therapies in metastatic tumors. Sequencing technologies provide only an overview of the aggregate of numerous cells. Computational approaches to de-mix a collective signal composed of the aberrations of a mixed cell population of a tumor sample into its individual components are not available. We propose an evolutionary framework for deconvolving data from a single genome-wide experiment to infer the composition, abundance and evolutionary paths of the underlying cell subpopulations of a tumor. We have developed an algorithm (TrAp) for solving this mixture problem. In silico analyses show that TrAp correctly deconvolves mixed subpopulations when the number of subpopulations and the measurement errors are moderate. We demonstrate the applicability of the method using tumor karyotypes and somatic hypermutation data sets. We applied TrAp to Exome-Seq experiment of a renal cell carcinoma tumor sample and compared the mutational profile of the inferred subpopulations to the mutational profiles of single cells of the same tumor. Finally, we deconvolve sequencing data from eight acute myeloid leukemia patients and three distinct metastases of one melanoma patient to exhibit the evolutionary relationships of their subpopulations.
The All-Hex Geode-Template for Conforming a Diced Tetrahedral Mesh to any Diced Hexahedral Mesh

Take a hexahedral mesh and an adjoining tetrahedral mesh that splits each boundary quadrilateral into two triangles. Separate the meshes with a buffer layer of hexes. Dice the original hexes into eight, and the tetrahedra into four hexahedra. Then I show that the buffer layer hexes can be filled with the geode-template, creating a conforming all-hex mesh of the entire model. The geode-template is composed of 26 hexahedra. The hexahedra have acceptable quality, depending on the geometry of the buffer layer. The method used to generate the geode-template is general, based on interleaving completed dual surfaces, and might be extended to other transition problems.
Inviscid transonic flow over airfoils

A procedure is presented to calculate steady supercritical planar flows over lifting airfoils using an unsteady approach, where the steady flow is obtained as the asymptotic flow for large times. The unsteady flow is generated by impulsively imposing the airfoil boundary condition in an initially uniform flow. The resulting flow is calculated by a finite difference analogue to the unsteady Euler equations using a diffusing second-order difference scheme. Here an artificial viscosity appears by which shock waves acquire a steep profile. The procedure is used to calculate the flows over one of the nonlifting symmetrical shockless profiles derived by Nieuwland, using the hodograph method, and over a lifting NAG A 64A-410 profile. Results agree well with experiments, with local differences accountable by a BusemannGuderley instability in the first case, and by viscous effects in the second case.
Adiabatic preparation of topological order.

Topological order characterizes those phases of matter that defy a description in terms of symmetry and cannot be distinguished in terms of local order parameters. Here we show that a system of $n$ spins forming a lattice on a Riemann surface can undergo a second order quantum phase transition between a spin-polarized phase and a string-net condensed phase. This is an example of a quantum phase transition between magnetic and topological order. We furthermore show how to prepare the topologically ordered phase through adiabatic evolution in a time that is upper bounded by $O(\sqrt{n})$. This provides a physically plausible method for constructing and initializing a topological quantum memory.
Equity Carve-Outs as a Technology Commercialization Strategy: An Exploratory Case Study of Thermo Electron's Strategy

New ventures have advantages in commercializing some emerging technologies, especially disruptive technologies. To the extent that incumbent firms can imitate these advantages, they can create ontogenic capabilities. This study examines a very rare type of ontogenic capability for which there is promising theoretical support-the use of equity carve-outs to commercialize emerging technologies. Only one company, Thermo Electron, has implemented an articulated or formal strategy for technology carve-outs. This paper presents an exploratory case study of Thermo's carve-out strategy that explains why the strategy failed and how technology carve-outs could be made feasible. If used as a temporary way station for technologies until their relatedness and economic potential are resolved, technology carve-outs could be an important tool in technology companies' portfolios of commercialization strategies.
Asymmetric Friedel-crafts reaction of indoles with imines by an organic catalyst.

In this communication, we report an asymmetric Friedel−Crafts reaction of indoles with imines catalyzed by a bifunctional cinchona alkaloid catalyst. This is the first efficient organocatalytic asymmetric Friedel−Crafts reaction of indoles with imines. This reaction is operationally simple and, unprecedentedly, affords high enantioselectivity for a wide range of indoles and both aryl and alkyl imines. This establishes a direct, convergent, and versatile approach to optically active 3-indolyl methanamines, a structural motif embedded in numerous indole alkaloids and synthetic indole derivatives.
Toward an Understanding of the Progenitors of Gamma-Ray Bursts

The various possibilities for the origin ("progenitors") of gamma-ray bursts (GRBs) manifest in differing observable properties. Through deep spectroscopic and high-resolution imaging observations of some GRB hosts, I demonstrate that well-localized long-duration GRBs are connected with otherwise normal star-forming galaxies at moderate redshifts of order unity. Using high-mass binary stellar population synthesis models, I quantify the expected spatial extent around galaxies of coalescing neutron stars, one of the leading contenders for GRB progenitors. I then test this scenario by examining the offset distribution of GRBs about their apparent hosts making extensive use of ground-based optical data from Keck and Palomar and space-based imaging from the Hubble Space Telescope. The offset distribution appears to be inconsistent with the coalescing neutron star binary hypothesis (and, similarly, black-hole-neutron star coalescences); instead, the distribution is statistically consistent with a population of progenitors that closely traces the ultra-violet light of galaxies. This is naturally explained by bursts which originate from the collapse of massive stars ("collapsars"). This claim is further supported by the unambiguous detections of intermediate-time (approximately three weeks after the bursts) emission "bumps" which appear substantially more red than the afterglows themselves. I claim that these bumps could originate from supernovae that occur at approximately the same time as the associated GRB; if true, GRB 980326 and GRB 011121 provide strong observational evidence connecting cosmological GRBs to high-redshift supernovae and implicate massive stars as the progenitors of at least some long-duration GRBs. Regardless of the true physical origin of these bumps, it appears that all viable alternative models of these bumps (such as dust scattering of the afterglow light) require a substantial amount of circumburst matter that is distributed as a wind-stratified medium; this too, implicates massive stars. Also suggested herein are some future observations which could further solidify or refute the supernova claim. In addition to the observational and modeling work, I also constructed the Jacobs Camera (JCAM), a dual-beam optical camera for the Palomar 200-inch Telescope designed to follow-up rapid GRB localizations.
Meaningfulness of Occupations as an Occupational-Life-Trajectory Attractor

Abstract According to Royeen (2003), chaos/complexity theory might be better suited than linear methods to provide a conceptual framework for the study of occupation and occupational behavior because of the complexity of these phenomena. The purpose of this paper is to present one way of conceptualizing human occupational life using some constructs from chaos/ complexity theory. It is proposed that human occupational life might be understood as an occupational‐life‐trajectory consisting of a repertoire of occupations chosen and performed over time. An argument is made, using empirical evidence from a previous pilot study (Ikiugu & Rosso, 2004), that meaningfulness may be viewed as an attractor for this trajectory, with conditions that make individuals perceive occupations to be meaningful forming a basin of attraction (conditions structuring patterns of participation in occupations). Such a view of meaningfulness may be one way of understanding the nature, structure, and features of occupation.
Rough solutions of the Einstein constraint equations on compact manifolds

We construct low regularity solutions of the vacuum Einstein constraint equations on compact manifolds. On 3-manifolds we obtain solutions with metrics in Hs where s > 3/2. The constant mean curvature (CMC) conformal method leads to a construction of all CMC initial data with this level of regularity. These results extend a construction from [10] that treated the asymptotically Euclidean case.
Homogeneous products of conjugacy classes

Let G be a finite group and a ∈G. Let a G ={g −1 a g | g ∈ G} be the conjugacy class of a in G. Assume that a G and b G are conjugacy classes of G with the property that C G (a)=C G (b). Then a G b G is a conjugacy class if and only if [a,G]=[b,G]=[ab,G] and [ab,G] is a normal subgroup of G.
Gravitational radiation and rotation of accreting neutron stars

Recent discoveries by the Rossi X-Ray Timing Explorer indicate that most of the rapidly accreting (${u{M}{"705F}}$ -->${u{M}{"705F}}$ --> 10 -->−11 M${s}$ -->$t SUBgt {s}t/SUBgt $ --> yr -->−1) weakly magnetic (B10 -->11 G) neutron stars in the Galaxy are rotating at spin frequencies ν -->s 250 Hz. Remarkably, they all rotate in a narrow range of frequencies (no more than a factor of 2, with many within 20% of 300 Hz). I suggest that these stars rotate fast enough so that, on average, the angular momentum added by accretion is lost to gravitational radiation. The strong νs-dependence of the angular momentum loss rate from gravitational radiation then provides a natural reason for similar spin frequencies. Provided that the interior temperature has a large-scale asymmetry misaligned from the spin axis, then the temperature-sensitive electron captures in the deep crust can provide the quadrupole needed ( ~10 -->−7MR -->2) to reach this limiting situation at ν -->s ≈ 300 Hz. This quadrupole is only present during accretion and makes it difficult to form radio pulsars with ν -->s > (600-800) Hz by accreting at ${u{M}{"705F}}$ -->${u{M}{"705F}}$ --> 10 -->−10 M${s}$ -->$t SUBgt {s}t/SUBgt $ --> yr -->−1. The gravity wave strength is h -->c ~(0.5-1) × 10 -->−26 from many of these neutron stars and greater than 2 × 10 -->−26 for Sco X-1. Prior knowledge of the position, spin frequency, and orbital periods will allow for deep searches for these periodic signals with gravitational wave interferometers (LIGO, VIRGO, and the dual-recycled GEO 600 detector), and experimenters need to take such sources into account. Sco X-1 will most likely be detected first.
Anisotropies in magnetic field evolution and local Lyapunov exponents

The natural occurrence of small scale structures and the extreme anisotropy in the evolution of a magnetic field embedded in a conducting flow is interpreted in terms of the properties of the local Lyapunov exponents along the various local characteristic (un)stable directions for the Lagrangian flow trajectories. The local Lyapunov exponents and the characteristic directions are functions of Lagrangian coordinates and time, which are completely determined once the flow field is specified. The characteristic directions that are associated with the spatial anisotropy of the problem, are prescribed in both Lagrangian and Eulerian frames. Coordinate transformation techniques are employed to relate the spatial distributions of the magnetic field, the induced current density, and the Lorentz force, which are usually followed in Eulerian frame, to those of the local Lyapunov exponents, which are naturally defined in Lagrangian coordinates.
Redundant information from thermal illumination: quantum Darwinism in scattered photons

We study quantum Darwinism, the redundant recording of information about the preferred states of a decohering system by its environment, for an object illuminated by a blackbody. We calculate the quantum mutual information between the object and its photon environment for blackbodies that cover an arbitrary section of the sky. In particular, we demonstrate that more extended sources have a reduced ability to create redundant information about the system, in agreement with previous evidence that initial mixedness of an environment slows—but does not stop—the production of records. We also show that the qualitative results are robust for more general initial states of the system.
Throughput-optimal scheduling in multichannel access point networks under infrequent channel measurements

We consider the problem of uplink/downlink scheduling in a multichannel wireless access point network where channel states differ across channels as well as users, vary with time, and can be measured only infrequently. We demonstrate that, unlike infrequent measurement of queue lengths, infrequent measurement of channel states reduce the maximum attainable throughput. We then prove that in frequency division multiplexed systems, a dynamic scheduling policy that depends on both the channel rates (averaged over the measurement interval) and the queue lengths, is throughput optimal. We also generalize the scheduling policy to solve the joint power allocation and scheduling problem. In addition, we provide simulation studies that demonstrate the impact of the frequency of channel and queue state measurements on the average delay and attained throughput.
Optimizing a variable-rate diffusion to hit an infinitesimal target at a set time

I consider a stochastic optimization problem for a one-dimensional continuous martingale whose diffusion rate is constrained to be between two positive values $r_{1}<r_{2}$. The problem is to find an optimal adapted strategy for the choice of diffusion rate in order to maximize the chance of hitting an infinitesimal region around the origin at a set time in the future. More precisely, the parameter associated with "the chance of hitting the origin" is the exponent for a singularity induced at the origin of the final time probability density. I show that the optimal exponent solves a transcendental equation depending on the ratio $\frac{r_{2}}{r_{1}}$.
Some fluorinated heterocyclic and acyclic derivatives of chlorocarbonylsulfenyl chloride

Abstract For the first time, fluorinated oxathialones, polyfluoroalkylchlorothioformates, chlorocarbonylpolyfluoroalkylsulfenate esters, a chlorocarbonylhexafluoroisopropylidenimino sulfenate, and a 5-tri-fluoromethyl-2-oxo-1,3,4-oxathiazole were synthesized by reacting chlorocarbonylsulfenyl chloride with RfC(O)CH2C(O)R′ (Rf = CF3; R'= CF3, OC2H5), RfO-Li+ (Rf = CF3CH2, (CF3)2C=N-Li+ and CF3C(O)NH2. Perfluorosuccinic acid and mercury(II) trifluoroacetate with ClC(O)SCI gave their respective anhydrides.
LR-visibility in polygons

We give a linear-time algorithm which, for a simple polygon P, computes all pairs of points s and t on P that admit LR-visibility. The points s and t partition P into two subchains. We say that P is LR-visible with respect to s and t if each point of P on the chain from s to t is visible from some point of the chain from t to s and vice-versa.