cssi/SciSciGPT-SciSciNet huggingface dataset:
Structure development in the early stages of crystallization during melt spinning

The earliest stage of crystallization during melt spinning was examined for four polymers: HDPE, PVDF, nylon 6 and poly(oxymethylene). The four polymers have very similar melt viscosities. Of particular interest is the dependence of the time for the onset of detectable crystallization on the take-up speed. The results for all four polymers lie on the same onset time versus take-up speed curve, indicating that this condition depends chiefly upon chain orientation and not appreciably on chain chemistry or specific undercooling. The result is consistent with a condition of critical strain level. A similar, but less stringent, result is found for further crystallization in the spinline.
A Global Turbulence Model for Neutrino-driven Convection in Core-collapse Supernovae

Simulations of core-collapse supernovae (CCSNe) result in successful explosions once the neutrino luminosity exceeds a critical curve, and recent simulations indicate that turbulence further enables explosion by reducing this critical neutrino luminosity. We propose a theoretical framework to derive this result and take the first steps by deriving the governing mean-field equations. Using Reynolds decomposition, we decompose flow variables into background and turbulent flows and derive self-consistent averaged equations for their evolution. As basic requirements for the CCSN problem, these equations naturally incorporate steady-state accretion, neutrino heating and cooling, non-zero entropy gradients, and turbulence terms associated with buoyant driving, redistribution, and dissipation. Furthermore, analysis of two-dimensional (2D) CCSN simulations validate these Reynolds-averaged equations, and we show that the physics of turbulence entirely accounts for the differences between 1D and 2D CCSN simulations. As a prelude to deriving the reduction in the critical luminosity, we identify the turbulent terms that most influence the conditions for explosion. Generically, turbulence equations require closure models, but these closure models depend upon the macroscopic properties of the flow. To derive a closure model that is appropriate for CCSNe, we cull the literature for relevant closure models and compare each with 2D simulations. These models employ local closure approximations and fail to reproduce the global properties of neutrino-driven turbulence. Motivated by the generic failure of these local models, we propose an original model for turbulence which incorporates global properties of the flow. This global model accurately reproduces the turbulence profiles and evolution of 2D CCSN simulations.
Joint Source-Channel Rate Allocation in Parallel Channels

A fast rate-optimal rate allocation algorithm is proposed for parallel transmission of scalable images in multichannel systems. Scalable images are transmitted via fixed-length packets. The proposed algorithm selects a subchannel, as well as a channel code rate for each packet, based on the signal-to-noise ratios (SNRs) of the subchannels. The resulting scheme provides unequal error protection of source bits and significant gains are obtained over equal error protection schemes. An application of the proposed algorithm to JPEG2000 transmission shows the advantages of exploiting differences in SNRs between subchannels. Multiplexing of multiple sources is also considered, and additional gains are achieved by exploiting information diversity among the sources.
The Children of Parents Exposed to Atomic Bombs: Estimates of the Genetic Doubling Dose of Radiation for Humans

The data collected in Hiroshima and Nagasaki during the past 40 years on the children of survivors of the atomic bombings and on the children of a suitable control population are analyzed on the basis of the newly revised estimates of radiation doses. No statistically significant effects emerge with respect to eight different indicators. Since, however, it may confidently be assumed some mutations were induced, we have taken the data at face value and calculated the minimal gametic doubling doses of acute radiation for the individual indicators at various probability levels. An effort has also been made to calculate the most probable doubling dose for the indicators combined. The latter value is between 1.7 and 2.2 Sv. It is suggested the appropriate figure for chronic radiation would be between 3.4 and 4.5 Sv. These estimates suggest humans are less sensitive to the genetic effects of radiation than has been assumed on the basis of past extrapolations from experiments with mice.
Late Light Curves of Normal Type Ia Supernovae

We present late-epoch optical photometry (BVRI) of seven normally luminous and superluminous Type Ia supernovae: SN 2000E, SN 2000ce, SN 2000cx, SN 2001C, SN 2001V, SN 2001bg, and SN 2001dp. The photometry of these objects was obtained using a template subtraction method to eliminate galaxy light contamination during aperture photometry. We show the optical light curves of these supernovae out to epochs of up to ~640 days after the explosion of the supernova. We show a linear decline in these data during the epoch of 200-500 days after explosion, with the decline rate in the B, V, and R bands equal to about 1.4 mag per 100 days, but the decline rate of the I-band is much shallower at 0.94 mag per 100 days.
Global economic governance: IMF quota reform

The paper examines the principles on which a reform of a quota based global economic institution like the International Monetary Fund (IMF) must be based, taking account of both the relative economic power of countries and the need for voice and representation of the poor countries. These principles are then used in the context of the global economic realities of the twenty-first century to examine the suitability of different variables in the IMF's quota formula. Based on this analysis a simple transparent formula is suggested, which will help increase the credibility and legitimacy of the IMF as a global macroeconomic and financial institution.
Bislactonizations of olefinic diacids with [hydroxy(tosyloxy)iodo]benzene

Abstract The reactions of [hydroxy(tosyloxy)iodo]benzene with a series of olefinic diacids to produce bislactones are reported. The products are the result of a stereospecific cis -addition of the two carboxylic acid functions to the double bond.
Random Skew Plane Partitions and the Pearcey Process

We study random skew 3D partitions weighted by qvol and, specifically, the q → 1 asymptotics of local correlations near various points of the limit shape. We obtain sine-kernel asymptotics for correlations in the bulk of the disordered region, Airy kernel asymptotics near a general point of the frozen boundary, and a Pearcey kernel asymptotics near a cusp of the frozen boundary.
Ecosystem fluxes of hydrogen: a comparison of flux-gradient methods

Abstract. Our understanding of biosphere–atmosphere exchange has been considerably enhanced by eddy covariance measurements. However, there remain many trace gases, such as molecular hydrogen (H2), that lack suitable analytical methods to measure their fluxes by eddy covariance. In such cases, flux-gradient methods can be used to calculate ecosystem-scale fluxes from vertical concentration gradients. The budget of atmospheric H2 is poorly constrained by the limited available observations, and thus the ability to quantify and characterize the sources and sinks of H2 by flux-gradient methods in various ecosystems is important. We developed an approach to make nonintrusive, automated measurements of ecosystem-scale H2 fluxes both above and below the forest canopy at the Harvard Forest in Petersham, Massachusetts, for over a year. We used three flux-gradient methods to calculate the fluxes: two similarity methods that do not rely on a micrometeorological determination of the eddy diffusivity, K, based on (1) trace gases or (2) sensible heat, and one flux-gradient method that (3) parameterizes K. We quantitatively assessed the flux-gradient methods using CO2 and H2O by comparison to their simultaneous independent flux measurements via eddy covariance and soil chambers. All three flux-gradient methods performed well in certain locations, seasons, and times of day, and the best methods were trace gas similarity for above the canopy and K parameterization below it. Sensible heat similarity required several independent measurements, and the results were more variable, in part because those data were only available in the winter, when heat fluxes and temperature gradients were small and difficult to measure. Biases were often observed between flux-gradient methods and the independent flux measurements, and there was at least a 26% difference in nocturnal eddy-derived net ecosystem exchange (NEE) and chamber measurements. H2 fluxes calculated in a summer period agreed within their uncertainty and pointed to soil uptake as the main driver of H2 exchange at Harvard Forest, with H2 deposition velocities ranging from 0.04 to 0.10 cm s−1.
The use of the IBM 704 in the simulation of speech-recognition systems

The term speech-recognition device usually brings to mind a machine capable of duplicating the function of a human listener. Such a device not only would have to be capable of receiving and classifying acoustic stimuli, but also would have to be able to extract from these stimuli the message the speaker intended. To do this, a recognition machine must be familiar with the language statistics, and indeed, the entire human environment. Many years of investigation will be required before such a human replacement can be achieved.
STRESS TOLERANCE IN INTERTIDAL SEAWEEDS

Intertidal seaweeds are periodically exposed to air where they experience a variety of potentially stressful environmental conditions, including nutrient limitation, high light, high and low temperature, desiccation, and osmotic stress. This paper considers the current understanding of stress tolerance in intertidal seaweeds and discusses ways in which future research could increase our understanding of the role of environmental factors in the ecology and physiology of these algae. We believe research is required in at least three areas. 1) Laboratory physiological studies have established that correlations exist between stress tolerance and the vertical distribution of species. However, little information is available on the importance of stress in determining community structure in nature. Field experiments are essential to relate the impact of single or multiple stresses on the survival, growth, and reproductive output of macroalgae. In paticular, it is necessary to clarify the role of sublethal stress in determining the outcome of competitive interactions. 2) With the exception of obvious lethal effects or damage associated with extreme environmental conditions, such as unusually hot and dry weather, it is difficult to evaluate the occurrence and severity of stress in natural populations of seaweeds. There is a need to develop molecular and biochemical markers specific for individual stresses or groups of stresses to allow the unambiguous and direct determination of stress in situ. 3) Despite the apparent importance of stress in intertidal seaweeds, we are largely ignorant of the mechanistic basis of tolerance. The application of currently available tools of molecular and cell biology to the investigation of stress-induced transcriptional and translational changes could enormously increase our understanding of both the sites of, and pathways involved in, stress tolerance. In summary, there are numerous unanswered fundamental questions about the stress tolerance of intertidal seaweeds, providing opportunities for research ranging from field ecology to molecular biology and biochemistry.
Mismatch Characterization of Small Metal Fringe Capacitors

Even though small metal fringe capacitors are important for the realization of low-energy A/D converters, present literature is lacking experimental data on their mismatch characteristics. This paper describes a test structure and measurements results pertaining to the characterization of single-layer, lateral-field, 0.45-fF and 1.2-fF unit metal capacitors in a 32-nm SOI CMOS process. The measurement-inferred average standard deviations for these capacitances are 1.2% and 0.8%, respectively, confirming area scaling according to Pelgrom's matching law.
The Structured Distance to Ill-Posedness for Conic Systems

An important measure of conditioning of a conic linear system is the size of the smallest structured perturbation making the system ill-posed. We show that this measure is unchanged if we restrict to perturbations of low rank. We thereby derive a broad generalization of the classic Eckart-Young result characterizing the distance to ill-posedness for a linear map.
Numerical Simulation of Realistic High-Speed Inlets Using the Navier-Stokes Equations

The tlo\v fields of two-dimension al high-speed inlets of realistic engineering geometry are solved through numerical integration of the full Navier-Stokes equations. Two inlets are considered, representative of lowaltitude acceleration and high-altitude cruise configurations. The flowfield of each is affected strongly by the curvilinear geometry and shock/boundary-layer interactions. The numerical code solves the full mean compressible Navier-Stokes equations using the algorithm of MacCormack in conjunction with a curvilinear bodyoriented coordinate system. Turbulence is represented by a two-layer eddy viscosity model. The computed results compare very favorably with the experimental data.
The photochemical model of Titan’s atmosphere and ionosphere: A version without hydrodynamic escape

Abstract There are observational and theoretical evidences both in favor of and against hydrodynamic escape (HDE) on Titan, and the problem remains unsolved. A test presented here for a static thermosphere does not support HDE on Titan and Triton but favors HDE on Pluto. Cooling of the atmosphere by the HCN rotational lines is limited by rotational relaxation above 1100 km and self-absorption below 900 km on Titan. HDE can affect the structure and composition of the atmosphere and its evolution. Hydrocarbon, nitrile, and ion chemistries are strongly coupled on Titan, and attempts to calculate them separately may result in significant errors. Here we apply our photochemical model of Titan’s atmosphere and ionosphere to the case of no hydrodynamic escape. Our model is still the only after-Cassini self-consistent model of coupled neutral and ion chemistry. The lack of HDE is a distinct possibility, and comparing models with and without HDE is of practical interest. The mean difference between the models and the neutral and ion compositions observed by INMS are somewhat better for the model with HDE. A reaction of NH 2 with H 2 CN suggested by Yelle et al. (2009) reduces but does not remove a significant difference between the ammonia abundances in the models and INMS observations. Losses of methane and nitrogen and production and deposition to the surface of hydrocarbons and nitriles are evaluated in the model, along with lifetimes and evolutionary aspects.
Group-4 Dipyrrolylmethane Complexes in Intramolecular Olefin Hydroamination

Titanium and zirconium complexes bearing the 5,5-dimethyldipyrrolylmethane (dpm) ancillary ligand were tested for their activity in intramolecular hydroamination of olefins. The titanium precatalyst Ti(NMe2)2(dpm), despite being an excellent catalyst for intermolecular alkyne hydroamination, was a relatively poor catalyst for intramolecular olefin hydroamination. The zirconium derivative was significantly more active. With a secondary amine, [Zr(NMe2)2(dpm)]2 did catalyze the hydroamination reaction, albeit slowly. Consequently, the mechanism of the reaction with zirconium may use a 1,2-insertion into a Zr−N amido bond as the key mechanistic step, or the complex may be able to access both the [2 + 2]-cycloaddition and 1,2-insertion mechanisms. The zirconium precatalyst was structurally characterized by X-ray diffraction and is a dimer in the solid state, but solution molecular weight determination gave results closer to the monomer in benzene.
Eosinophilic vasculitis in an isolated central nervous system distribution.

Eosinophilic vasculitis has been described as part of the Churg–Strauss syndrome, but affects the central nervous system (CNS) in
Surfactant effects on thermocapillary interactions of deformable drops

Abstract A three-dimensional boundary-integral algorithm is used to study thermocapillary interactions of two deformable drops in the presence of bulk-insoluble, non-ionic surfactant. The primary effect of deformation is to slow down the rate of film drainage between drops in close approach and prevent coalescence in the absence of van der Waals forces. Both linear and non-linear models are used to describe the relationship between interfacial tension and surfactant surface concentration. In the linear model, non-monotonic behavior of the minimum separation between the drops as a function of the surface Peclet number Pe s is observed for equal drop and external medium viscosities and thermal conductivities. For bubbles with zero drop-to-medium viscosity and thermal conductivity ratios, however, the minimum separation increases with Pe s . There is a nearly linear relationship between the minimum drop separation and elasticity E. In the simplest non-linear equation of state, the product of the temperature and the surfactant concentration is retained by allowing non-zero values of the dimensionless gas constant Λ. For Λ = O ( 0.05 ) , it is possible for the smaller drop to move faster than the larger drop. In the Langmuir adsorption framework, the tendency of the smaller drop to catch up to the larger one decreases as the ratio of the equilibrium to maximum surfactant surface concentration increases. Finally, in the Frumkin model, a minimum in the drop separation occurs as a function of the interaction parameter λ F for trajectories with all other parameters held constant.
Do stock-for-stock merger acquirers manage earnings? Evidence from Japan

Abstract This paper examines the earnings management behavior of Japanese merger acquirers on the Tokyo Stock Exchange. Most Japanese mergers are transacted via stock swaps, when acquirers have incentive to manage pre-merger earnings to reduce the cost of acquisition. Consistent with this incentive, Japanese acquirers have significantly positive long-term abnormal accruals in the year prior to the merger announcement. Further analyses suggest that acquirers’ extent of earnings management is an increasing function of their economic benefit at stake, and a decreasing function of monitoring by banks and foreign investors.
One-pot synthesis of 1-alkyl-1H-indazoles from 1,1-dialkylhydrazones via aryne annulation.

The reaction of readily accessible 1,1-dialkylhydrazones with commercially available o-(trimethylsilyl)aryl triflates provides a direct one-step route to pharmaceutically important 1-alkylindazoles. The products are obtained in high yields by one-pot NCS-chlorination/aryne annulation or Ac2O-acylation/deprotection/aromatization protocols.
Pulsar Emission and Force-Free Electrodynamics

Pulsar emission should come primarily from the magnetic separatrix. Combining theory and observations, we show that force-free electrodynamics (FFE) gives an accurate description of the large-scale electromagnetic field in the magnetospheres of Crab-like pulsars. A robust prediction of FFE is the existence and stability of a singular current layer on the magnetic separatrix. We argue that most of the observed pulsar emission comes from this singular current layer.
Structural design language for coupled knowledge-based systems

Abstract A structural design language (SDL) has been developed in INTERLISP environment for building coupled knowledge-based expert systems for integrated design of a class of structures. The integrated design includes the preliminary design, structural analysis, design of members, design of connections, and computer-aided drafting of the final design. The complex body of knowledge needed for detailed design of a structure is fractionated into smaller and manageable knowledge sources, which are organized into a hierarchy of cooperating conceptual specialists. SDL provides a multiwindow graphics interface capable of displaying both the orthographic and isometric views of the frame structure and beam-column connections. A three-dimensional face frame representation is used for the graphic display of the beam-column connections. SDL has been used to develop a prototype knowledge-based system for integrated design of steel building structures consisting of moment-resisting frames.
Uncovering student values for hiring in the software industry

This paper provides an analysis of student responses to an exercise used in a computer ethics and a software engineering course to raise awareness of issues related to hiring, including issues of professional responsibility and diversity. Students from two different universities were asked to evaluate four candidates for two positions in a fictitious software company. They then developed a set of criteria for evaluation and constructed an argument to support their choices. After discussing their choice with others in the class, students could change their hiring decisions. Students' hiring criteria were coded using emergent categories, inferences in the arguments were coded according to the criteria, and reasons for changing hiring decisions were coded. Students considered criteria that fell into five areas: technical skills, soft skills, personal traits, previous employment, and career/job considerations. Reasons for changing hiring choices included previous experience, diversity considerations, people skills, leadership skills, and reaching consensus. The paper also reports inferences students made about the job candidates.
Extension theorems for paraboloids in the finite field setting

In this paper we study the Lp − Lr boundedness of the extension operators associated with paraboloids in \({{\mathbb F}_{q}^{d}}\) , where \({\mathbb{F}_{q}}\) is a finite field of q elements. In even dimensions d ≥ 4, we estimate the number of additive quadruples in the subset E of the paraboloids, that is the number of quadruples \({(x,y,z,w) \in E^4}\) with x + y = z+w. As a result, in higher even dimensions, we obtain the sharp range of exponents p for which the extension operator is bounded, independently of q, from Lp to L4 in the case when −1 is a square number in \({\mathbb{F}_{q}}\) . Using the sharp Lp −L4 result, we improve upon the range of exponents r, for which the L2 − Lr estimate holds, obtained by Mockenhaupt and Tao (Duke Math 121:35–74, 2004) in even dimensions d ≥ 4. In addition, assuming that −1 is not a square number in \({\mathbb{F}_{q}}\), we extend their work done in three dimension to specific odd dimensions d ≥ 7. The discrete Fourier analytic machinery and Gauss sum estimates make an important role in the proof.
DISORDER EFFECTS ON SMALL-POLARON FORMATION AND HOPPING

It was noted some time ago that many properties of amorphous semiconductors could be explained if the charge carriers self-trapped to form small polarons. Self trapping occurs when an electronic carrier lingers at a site long enough to permit surrounding atoms to displace in response to the presence of the carrier. The electronic carrier then becomes severely localized within a potential well produced by the atomic displacements. This self-trapped carrier cannot move unless the atoms alter their positions. The localized carrier together with the atomic displacement pattern that confines it is termed a small polaron. The adjective small denotes the severe localization of the electronic state. The energy of a small polaron in a covalent solid is lower than that of a static electron by E{sub b} {triple_bond} F{sup 2}/2k, where F is the force between the carrier and atoms adjacent to it, and k is the material`s stiffness constant. As a result of its severe localization, a small polaron generally moves by phonon-assisted hopping. Small-polarons will only form in covalent crystals whose electronic halfbandwidths are sufficiently narrow, E{sub b} > W. The absence of small polaronic carriers in most covalent crystals presumably indicates that E{sub b} < W inmore » these instances. However, evidence of small polarons is commonly found in disordered materials despite the estimates of E{sub b} and W not being significantly different from those of crystals. It is found that only modest energetic disorder is required to induce small-polaron formation. Here the author succinctly describes essential elements of this work. Second, the author addresses the role of disorder on the adiabatic hopping motion of small polarons.« less
Inflation from symmetry breaking below the Planck scale

Abstract We investigate general scalar field potentials V ( φ ) for inflationary cosmology arising from spontaneous symmetry breaking. We find that potentials which are dominated by terms of order φ m with m > 2 can satisfy observational constraints at an arbitrary symmetry breaking scale. Of particular interest, the spectral index of density fluctuations is shown to be independent of the specific form of the potential, depending only on the order m of the lowest non-vanishing derivative of V ( φ ) near its maximum. The results of a model with a broken SO(3) symmetry illustrate these features.
Subspace evasive sets

We construct explicit subspace-evasive sets. These are subsets of Fn of size |F|(1-e)n whose intersection with any k-dimensional subspace is bounded by a constant c(k,e). This problem was raised by Guruswami (CCC 2011) as it leads to optimal rate list-decodable codes of constant list size. The main technical ingredient is the construction of k low-degree polynomials whose common set of zeros has small intersection with any k-dimensional subspace.
Rational synthesis of meso-substituted chlorin building blocks.

Chlorins bearing synthetic handles at specific sites about the perimeter of the macrocycle constitute valuable building blocks. We previously developed methodology for preparing meso-substituted chlorin building blocks and now present methodology for preparing several complementary beta-substituted chlorin building blocks. The chlorins bear one or two beta substituents, one meso substituent, a geminal dimethyl group to lock in the chlorin hydrogenation level, and no flanking meso and beta substituents. The synthesis involves convergent joining of an Eastern half and a Western half. New routes have been developed to two beta-substituted bromo-dipyrromethane monocarbinols (Eastern halves). A new beta-substituted Western half was prepared following the method for preparing an unsubstituted Western half (3,3-dimethyl-2,3-dihydrodipyrrin). Chlorin formation is achieved by a two-flask process of acid-catalyzed condensation followed by metal-mediated oxidative cyclization. beta-Substituted chlorins have been prepared in 18-24% yield bearing a 4-iodophenyl group at the 8-position, a 4-iodophenyl group or a 4-[2-(trimethylsilyl)ethynyl]phenyl group at the 12-position, and a 4-iodophenyl group and a 4-[2-(trimethylsilyl)ethynyl]phenyl group at diametrically opposed beta-positions (2, 12). The latter building block makes possible the stepwise construction of linear multi-chlorin architectures. The chlorins exhibit typical absorption and fluorescence spectra. A systematic shift in the absorption maximum (637-655 nm for the free base chlorins, 606-628 nm for the zinc chlorins) and intensity of the chlorin Q(y)() band (epsilon up to 79 000 M(-)(1) cm(-)(1)) is observed depending on the location of the substituents. The characteristic spectral features and location of substituents in defined positions make these chlorins well suited for a variety of applications in biomimetic and materials chemistry.
Indium-mediated allylation of aldehydes, ketones and sulfonimines with 2-(alkoxy)allyl bromides

Abstract 2-(Alkoxy)propenyl bromides are readily prepared from 1,3-dibromo-2-propanol in a two-step sequence involving hydroxyl protection and sodium hydride-induced dehydrobromination. Indium-mediated allylation of aldehydes, ketones, and sulfonimines with 2-(alkoxy)propenyl bromides furnishes the corresponding homoallylic alcohols and sulfonamines in good yields. The products can be easily transformed into β-hydroxy ketones and esters, as well as substituted dihydropyrans, and protected β-amino acids. Chiral 2-(alkoxy)propenyl halides, derived from (−)-menthol and d -glucal, furnish diastereomerically enriched products.
Formation of the first stars and quasars

We examine various observable signatures of the first generation of stars and low-luminosity quasars, including the metal enrichment, radiation background, and dust opacity/emission that they produce. We calculate the formation history of collapsed baryonic halos, based on an extension of the Press-Schechter formalism, incorporating the effects of pressure and H2-dissociation. We then use the observed C/H ratio at z=3 in the Lyman-α forest clouds to obtain an average the star formation efficiency in these halos. Similarly, we fit the efficiency of black-hole formation, and the shape of quasar light curves, to match the observed quasar luminosity function (LF) between z=2−4, and use this fit to extrapolate the quasar LF to faint magnitudes and high redshifts. To be consistent with the lack of faint point-sources in the Hubble Deep Field, we impose a lower limit of ∼ 75 km s−1 for the circular velocities of halos harboring central black holes. We find that in a ΛCDM model, stars reionize the IGM at zreion=9−13, and quasars at z=12. Observationally, zreion can be measured by the forthcoming MAP and Planck Surveyor satellites, via the damping of CMB anisotropies by ∼10% on small angular scales due to electron scattering. We show that if reionization occurs later, at 5 ≲ zreion ≲ 10, then it can be measured from the spectra of individual sources. We also find that the Next Generation Space Telescope will be able to directly image about 1–40 star clusters, and a few faint quasars, from z >10 per square arcminute. The amount of dust produced by the first supernovae has an optical depth of τ=0.1−1 towards high redshift sources, and the reprocessed UV flux of stars and quasars distorts the cosmic microwave background radiation (CMB) by a Compton y-parameter comparable to the COBE limit, y ∼ 1.5 × 10−5.
Palladium-catalyzed C-H perfluoroalkylation of arenes.

A new Pd-catalyzed reaction for the coupling between perfluoroalkyl iodides (RFI) and simple aromatic substrates is described. The perfluoroalkylated arene products are obtained in good to excellent yields in the presence of a phosphine-ligated Pd catalyst and Cs2CO3 as a base. The development, optimization, scope, and preliminary mechanistic studies of these transformations are reported.
Recent experimental studies of edge and internal transport barriers in the DIII-D tokamak

Results from recent experiments on the DIII-D tokamak have revealed many important details on transport barriers at the plasma edge and in the plasma core. These experiments include: (a) the formation of the H-mode edge barrier directly by pellet injection; (b) the formation of a quiescent H-mode edge barrier (QH-mode) which is free from edge localized modes, but which still exhibits good density and radiative power control; (c) the formation of multiple transport barriers, such as the quiescent double barrier (QDB) which combines an internal transport barrier with the quiescent H-mode edge barrier. Results from the pellet-induced H-mode experiments indicate that: (a) the edge temperature (electron or ion) does not need to attain a critical value for the formation of the H-mode barrier, (b) pellet injection leads to an increased gradient in the radial electric field, Er, at the plasma edge; (c) the experimentally determined edge parameters at barrier transition are well below the predictions of several theories on the formation of the H-mode barrier, (d) pellet injection can lower the threshold power required to form the H-mode barrier. The quiescent H-mode barrier exhibits good density control as the result of continuous magnetohydrodynamic activity at the plasma edge called the edge harmonic oscillation (EHO). The EHO enhances the edge particle transport whilst maintaining a good energy transport barrier. The ability to produce multiple barriers in the QDB regime has led to long duration, high-performance plasmas with βNH89 values of 7 for up to 10 times the confinement time. Density profile control in the plasma core of QDB plasmas has been demonstrated using on-axis electron cyclotron heating.
Curved BPS domain wall solutions in five-dimensional gauged supergravity

We analyze the possibility of constructing supersymmetric curved domain wall solutions in five-dimensional = 2 gauged supergravity, which are supported by non-constant scalar fields belonging either to vector multiplets only or to vector and hypermultiplets. We show that the BPS equations for the warp factor and for the vector scalars are modified by the presence of a four-dimensional cosmological constant on the domain wall, in agreement with earlier results by DeWolfe, Freedman, Gubser and Karch. We also show that the cosmological constant on the domain wall is anti-de Sitter like and that it constitutes an independent quantity, not related to any of the objects appearing in the context of very special geometry.
VALIDATING EXPERT SYSTEM PROTOTYPES USING THE TURING TEST

Abstract High-performance, expert-level computer systems require that the expert system prototype be continously evaluated during its development. Expert system validation—that is, testing systems to ascertain whether they achieve acceptable performance levels—has with few exceptions been ad hoc, informal, and of dubious value. This paper describes a variant of the Turing Test technique that may be used to formalize the validation process. A microcomputer-based prototype expert system, the Hazardous Location Analyst (HLA), in the accident location analysis domain was used as a case study of the technique. Turing tests provide a blind method for multiple experts to assess expert system performance qualitatively, and provide a means of determining reasonable performance levels for the particular domain. The HLA has been modified based upon findings from the case study work done previously. The improved prototype was implemented in the City of Greensboro, North Carolina, and a set of 10 case studies are analyzed using the HLA, and by a Greensboro traffic engineer. The results were summarized in identical form and mailed to four traffic engineers outside of Greensboro. Their ratings of case study findings were summarized, and the results used to find a reasonable performance level for this application and to assess the performance of the HLA. The consistency of the expert ratings was also assessed. It was concluded that there exists excellent consistency among experts with regard to human performance, but not with regard to the HLA. This paper demonstrates that the Turing Test as a validation methodology provides an objective, quantitative way to assess system performance.
Galois structure of homogeneous coordinate rings

Suppose G is a finite group acting on a projective scheme X over a commutative Noetherian ring R. We study the RG-modules H 0 (X,F ⊗ L n ) when n > 0, and F and £ are coherent G-sheaves on X such that L is an ample line bundle. We show that the classes of these modules in the Grothendieck group G 0 (RG) of all finitely generated RG-modules lie in a finitely generated subgroup. Under various hypotheses, we show that there is a finite set of indecomposable RG-modules such that each H 0 (X, F⊗L n ) is a direct sum of these indecomposables, with multiplicities given by generalized Hilbert polynomials for n » 0.
Relating scattering amplitudes in bosonic and topological string theories

Abstract A formal relationship between scattering amplitudes in critical bosonic string theory and correlation functions of operators in topological string theory is found.
Summary talk for ISMD 06

I give an overview of the presentations at the International Symposium on Multiparticle Dynamics. 2006
A Multiwavelength Analysis of the Halo Planetary Nebula DdDm-1* **

We present new HST optical imagery as well as new UV and IR spectroscopic data obtained with the Hubble Space Telescope and Spitzer Space Telescope, respectively, of the halo planetary nebula DdDm-1. For the first time we present a resolved image of this object, which indicates that the morphology of DdDm-1 can be described as two orthogonal elliptical components in the central part surrounded by an extended halo. The extent of the emission is somewhat larger than was previously reported in the literature. We combine the spectral data with our own previously published optical measurements to derive nebular abundances of He, C, N, O, Ne, Si, S, Cl, Ar, and Fe. The metallicity, as gauged by oxygen, is found to be 0.60 dex below the solar value, confirming DdDm-1's status as a halo PN. In addition, we find that Si and Fe are markedly underabundant, suggesting their depletion onto dust. The very low C/O ratio suggests that the chemistry of the nebula should be consistent with an oxygen-rich environment. With regard to the unexpectedly low S abundance relative to O often seen in PNe, we find that the sulfur abundance of DdDm-1 is only slightly below the value expected based on the normal lockstep behavior between S and O observed in H II regions and blue compact galaxies. We performed a photoionization model analysis from which we inferred a central star effective temperature and luminosity of 55,000 K and 1000 L☉, respectively, implying an initial progenitor mass of <1 M☉. Finally, we report on a new radial velocity determination from echelle observations.
Status of Engine Rotor Burst Protection Program for Aircraft

CCOMPANYING today's use of turbomachiner y in aircraft is the associated danger that occasionally a highspeed rotor will fail and the fragments will damage equipment and threaten passenger safety. Such adverse effects can be reduced either by prevention of or protection against rotor bursts. A significant effort is being expended to improve methods for detecting defects during fabrication, operation, and maintenance. Despite such efforts, however, statistics continue to reflect the persistence of rotor failures. During the past 9 years, 170 uncontained failures of gas-turbine engine components were reported by U.S. commercial airlines. Accordingly, NASA has been sponsoring a research program with a view toward providing protection to the aircraft without imposing large weight penalties. This program is directed toward the development of criteria and methods for the design of practical devices to contain rotor fragments as well as to deflect them away from the critical aircraft components. The immediate aim is to develop meaningful tests and analytical methods to evaluate possible solutions. In order to generalize the results, experiments are closely coordinated with analytical methods. Tests, conducted in the Navy Containment Evaluation Facility,1"4 are compared with results of calculation methods developed by the Massachusetts Institute of Technology.5'6 Test rotors, modified to fail with predetermined sizes and shapes of fragments, are caused to impact containment/deflection devices in a spin chamber. The complex interaction between the fragments and the protective device is recorded by high-speed photography. Deformations of the containment/deflection device, measured on the photographs and related to the time reference, show the dynamic interaction. This paper highlights some of the accomplishments to date and presents future plans. Contents Simple tests were run first to support analysis. A blade was modified to fail at a specified speed and impact an aluminum alloy (2024-T4) freely supported containment ring (i.e., no restraints to motion in the plane of the ring). The response is show in Fig. 1 at the three elapsed times. Ring deflections around the circumference (at the alternate black and white marks) were recorded at approximately 30-jnsec intervals. Comparison of the measured and analytically predicted ring profiles after impact shows good agreement for this simple case. However, improvements in the calculation methods are being pursued to increase the accuracy of the predictions and to handle the interaction between more complex fragments and containment rings. The method of
Controlling the public wage bill in Portugal: the case of university professors

Public wages are a large share of the public budget in Portugal and, therefore, hiring freezes are a central feature of the efforts to control the public deficit. The system of public career advancement, however, may lead to increases in the wage bill even in the presence of hiring freezes. We estimate this wage drift effect in the case of university professors. We use a logit analysis with 1999 census data to identify the determinants of career advancement, to estimate the employment distribution in previous years and to obtain the corresponding wage bill. We estimate that the annual wage drift is 2.6%, a figure well above the gross domestic product growth rate and, therefore, we conclude that hiring freezes may be far from enough to stop the expansion of the public wage bill.
On the space-time curvature experienced by quasiparticle excitations in the Painlevé-Gullstrand effective geometry

Abstract We consider quasiparticle propagation in constant-speed-of-sound (iso-tachic) and almost incompressible (iso-pycnal) hydrodynamic flows, using the technical machinery of general relativity to investigate the “effective space-time geometry” that is probed by the quasiparticles. This effective geometry, described for the quasiparticles of condensed matter systems by the Painleve–Gullstrand metric, generally exhibits curvature (in the sense of Riemann) and many features of quasiparticle propagation can be re-phrased in terms of null geodesics, Killing vectors, and Jacobi fields. As particular examples of hydrodynamic flow we consider shear flow, a constant-circulation vortex, flow past an impenetrable cylinder, and rigid rotation.
A variant of the hypergraph removal lemma

Recent work of Gowers [T. Gowers, A new proof of Szemeredi's theorem, Geom. Funct. Anal. 11 (2001) 465-588] and Nagle, Rodl, Schacht, and Skokan [B. Nagle, V. Rodl, M. Schacht, The counting lemma for regular k-uniform hypergraphs, Random Structures Algorithms, in press; V. Rodl, J. Skokan, Regularity lemma for k-uniform hypergraphs, Random Structures Algorithms, in press; V. Rodl, J. Skokan, Applications of the regularity lemma for uniform hypergraphs, preprint] has established a hypergraph removal lemma, which in turn implies some results of Szemeredi [E. Szemeredi, On sets of integers containing no k elements in arithmetic progression, Acta Arith. 27 (1975) 299-345], and Furstenberg and Katznelson [H. Furstenberg, Y. Katznelson, An ergodic Szemeredi theorem for commuting transformations, J. Anal. Math. 34 (1978) 275-291] concerning one-dimensional and multidimensional arithmetic progressions, respectively. In this paper we shall give a self-contained proof of this hypergraph removal lemma. In fact we prove a slight strengthening of the result, which we will use in a subsequent paper [T. Tao, The Gaussian primes contain arbitrarily shaped constellations, preprint] to establish (among other things) infinitely many constellations of a prescribed shape in the Gaussian primes.
The Penetration Resistance of a Titanium Alloy against Jets from Tantalum Shaped Charge Liners

Titanium alloys, notably Ti—6Al—4V, are known to provide high mass effectiveness against kinetic energy penetrators. However, the penetration effectiveness of titanium against shaped charge jets has not been investigated in detail. An experimental study was conducted with Ti—6Al—4V billets impacted by shaped charge jets formed from 100–mm, 42° conical shaped charge liners fabricated from tantalum. This work represents the first study of hypervelocity, high–density jet penetration into titanium alloys.
Structure of a photodimer of 3-acetoxy-2-inden-1-one: 9,10-dioxoindano[2',3':4,3]cyclobuta[1,2-b]indan-4b,4c-diyl diacetate.

C22H16O6, Mr = 376.37, monoclinic, P21/c, a = 9.555 (3), b = 15.664 (2), c = 12.300 (4) A, beta = 100.08 (2) degrees, V = 1812.5 (5) A3, Z = 4, Dx = 1.379 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 8.0 cm-1, F(000) = 784, room temperature, R = 0.047, wR = 0.064 for 3203 observed reflections [I greater than 3 sigma (I)]. The molecule exists as the syn-trans isomer in the crystal. The crystal structure exhibits a number of C--H...O intermolecular contacts.
Active mirror technology for large space telescopes

Future space telescopes rely on advances in technology to enable fabrication of primary mirrors with orders of magnitude more area, yet similar mass as current mirrors. This requires a shift of paradigm from the concept of the mirror as a rigid, stable unit, to the idea of the mirror as a system that uses active control to maintain the figure of a flexible surface. We discuss issues for this new class of optics and present status on a 2-m prototype mirror for NGST.
A general, convenient way to carborane-containing amino acids for boron neutron capture therapy

Abstract A general convenient procedure for the synthesis of caborane-containing amino acids in good yield has been developed. The synthesis of o-carboranylalanine 1, O-(o-carboran-1-ylmethyl)-tyrosine 2 and p-(o-carboran-1-yl)-phenylalanine 3 is reported.
Agricultural Policies and Migration in a U.S.-Mexico Free Trade Area: A Computable General Equilibrium Analysis

Abstract A United States-Mexico agreement to form a free trade area (FTA) is analyzed using an 11-sector, three-country, computable general equilibrium model that explicity models farm programs and labor migration. The model incorporates both rural-urban migration within Mexico and international migration between Mexico and the United States. In the model, sectoral import demands are specified with a flexible functional form, an empirical improvement over earlier specifications, which use a constant elasticity of substitution function. Using the model, we identify trade-offs among bilateral trade growth, labor migration, and agricultural program expenditures under alternative FTA scenarios. Trade liberalization in agriculture greatly increases rural- urban migration within Mexico and migration from Mexico to the United States. Migration is reduced if Mexico grows relative to the United States and also if Mexico retains farm support programs. However, the more support that is provided to the Mexican agricultural sector, the smaller is bilateral trade growth. The results indicate a policy trade-off between rapidly achieving gains from trade liberalization and providing a transition period long enough to assimilate displaced labor in Mexico without undue strain.
Dissipation and Decoherence in a Quantum Oscillator

The time development of the reduced density matrix for a quantum oscillator damped by coupling it to an ohmic environment is calculated via an identity of the Debye-Waller form. Results obtained some years ago by Hakim and the author in the free-particle limit(10) are thus recovered. The evolution of a free particle in a prepared initial state is examined, and a previously published exchange(5,9) is illuminated with figures showing no decoherence without dissipation.
From the ‘econometrics of capital punishment’ to the ‘capital punishment’ of econometrics: on the use and abuse of sensitivity analysis

The academic debate over the deterrent effect of capital punishment has intensified again with a major policy outcome at stake. About two dozen empirical studies have recently emerged that explore the issue. Donohue and Wolfers (2005) claim to have examined the recent studies and shown the evidence not to be robust to specification changes. We argue that the narrow scope of their study does not warrant this claim. Moreover, focusing on our two studies that they have examined, we show the deterrence findings to be robust, while their work has serious flaws and their reporting appears to be selective. The selectivity is biased towards showing ‘no deterrence’.