cssi/SciSciGPT-SciSciNet huggingface dataset:
NLO BFKL AND ANOMALOUS DIMENSIONS OF LIGHT-RAY OPERATORS

The anomalous dimensions of light-ray operators of twist two are obtained by analytical continuation of the anomalous dimensions of corresponding local operators. I demonstrate that the asymptotics of these anomalous dimensions at the "BFKL point" j → 1 can be obtained by comparing the light-cone operator expansion with the high-energy expansion in Wilson lines.
A Newton collocation method for solving dynamic bargaining games

We develop and implement a collocation method to solve for an equilibrium in the dynamic legislative bargaining game of Duggan and Kalandrakis 2008, unpublished manuscript. We formulate the collocation equations in a quasi-discrete version of the model, and we show that they are locally Lipchitz continuous and directionally differentiable. In numerical experiments, we successfully implement a globally convergent variant of Broyden’s method on a preconditioned version of the collocation equations, and the method economizes on computation cost by more than 50% compared to the value iteration method. We rely on a continuity property of the equilibrium set to obtain increasingly precise approximations of solutions to the continuum model. We showcase these techniques with an illustration of the dynamic core convergence theorem of Duggan and Kalandrakis 2008, unpublished manuscript in a nine-player, two-dimensional model with negative quadratic preferences.
Magnetization and design of multistrand superconducting conductors

Magnetization of cabled and braided samples which are long compared to their transposition lengths has been measured in a uniform magnetizing field directed at right angles to their widths. A separated double pancake with nonuniform windings was constructed to produce a suitably uniform radial field in which long coiled samples could be placed. Magnetization losses have also been measured in the ISA I magnet at BNL. Results are compared with theories which are due to Wilson[1] and, basically, Morgan.[2] Also, design optimization procedures have been defined for the use of multistrand conductors in magnet windings.
PROBING THE UNIVERSE'S TILT WITH THE COSMIC INFRARED BACKGROUND DIPOLE

Conventional interpretation of the observed cosmic microwave background (CMB) dipole is that all of it is produced by local peculiar motions. Alternative explanations requiring part of the dipole to be primordial have received support from measurements of large-scale bulk flows. A test of the two hypotheses is whether other cosmic dipoles produced by collapsed structures later than the last scattering coincide with the CMB dipole. One background is the cosmic infrared background (CIB) whose absolute spectrum was measured to ~30% by the COBE satellite. Over the 100-500??m wavelength range its spectral energy distribution can provide a probe of its alignment with the CMB. This is tested with the COBE FIRAS data set which is available for such a measurement because of its low noise and frequency resolution which are important for Galaxy subtraction. Although the FIRAS instrument noise is in principle low enough to determine the CIB dipole, the Galactic foreground is sufficiently close spectrally to keep the CIB dipole hidden. A similar analysis is performed with DIRBE, which?because of the limited frequency coverage?provides a poorer data set. We discuss strategies for measuring the CIB dipole with future instruments to probe the tilt and apply it to the Planck, Herschel, and the proposed Pixie missions. We demonstrate that a future FIRAS-like instrument with instrument noise a factor of ~10 lower than FIRAS would make a statistically significant measurement of the CIB dipole. We find that the Planck and Herschel data sets will not allow a robust CIB dipole measurement. The Pixie instrument promises a determination of the CIB dipole and its alignment with either the CMB dipole or the dipole galaxy acceleration vector.
Identification of Domains on the 39‐kDa Protein That Inhibit the Binding of Ligands to the Low Density Lipoprotein Receptor–Related Protein

The low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP/alpha 2MR) binds and internalizes several plasma proteins including tissue-type plasminogen activator (t-PA) and alpha 2-macroglobulin-protease complexes (alpha 2M*). A 39-kDa protein that copurifies with LRP/alpha 2MR inhibits the binding and uptake of ligands by LRP/alpha 2MR, including t-PA and alpha 2M*. To define domains on the 39-kDa protein which are essential for inhibition of t-PA and alpha 2M* binding to LRP/alpha 2MR, we have generated bacterial expression constructs encoding discrete regions of the 39-kDa protein as fusion proteins with glutathione S-transferase. Inhibition of t-PA and alpha 2M* binding to LRP/alpha 2MR on rat hepatoma MH1C1 cells are shown to require amino acid residues 18-24 and 100-107 on the 39-kDa protein. Inhibition of t-PA but not alpha 2M* binding to LRP/alpha 2MR is also mediated by residues 200-225 and 311-319. The same 39-kDa protein constructs that inhibit alpha 2M* and t-PA binding to MH1C1 cells are able to bind directly to purified LRP/alpha 2MR immobilized on nitrocellulose. Thus, our studies demonstrate several specific regions on the 39-kDa protein which are required for the inhibition of t-PA and alpha 2M* binding to LRP/alpha 2MR.
A Social Choice Lemma on Voting Over Lotteries with Applications to a Class of Dynamic Games

We prove a lemma characterizing majority preferences over lotteries on a subset of Euclidean space. Assuming voters have quadratic von Neumann–Morgenstern utility representations, and assuming existence of a majority undominated (or “core”) point, the core voter is decisive: one lottery is majority-preferred to another if and only if this is the preference of the core voter. Several applications of this result to dynamic voting games are discussed.
From Brown to busing

Abstract Brown v. Board of Education had little immediate effect on the dual system of education in the South; by the early 1970s, however, Southern schools were the most racially integrated in the country. This paper uses newly assembled and uniquely comprehensive data to document how different types of Southern school districts made this transition. Controlling for other factors, we find larger districts were more likely to be under court supervision both early and ever; over time the enrollment threshold for court supervision fell. Poorer districts—which stood to lose larger federal grants if they failed to desegregate—were particularly likely to desegregate between 1964 and 1968. Black enrollment share did not impede “token” desegregation, but was an important predictor of both resistance to intensive desegregation and being supervised by a court in later years. By the end of our sample, in 1976, districts in Alabama and Louisiana were still significantly less integrated than in other states. Within states, however, despite having begun the 1960s with higher levels of segregation and retained them for longer than other districts, districts with stronger historical preferences for segregation had desegregated nearly as much as other districts by 1976; this may be related to their higher rate of court supervision in later years.
Analyses of thin films and surfaces by cold neutron depth profiling

Abstract Neutron depth profiling (NDP) has been employed to examine manufacturing processes and starting materials for several high-technology applications. NDP combines nuclear and atomic physics processes to determine the concentration profile of several light elements in the near surface region (∼1–8 μm) of smooth surfaces. The method is both quantitative and non-destructive. Analyses are performed at the Center for Neutron Research at NIST on samples prepared at Corning Incorporated. Two types of samples have been analyzed: (1) Boron profiles are measured in glasses to determine B loss due to its volatilization during manufacturing. Surface depletion of B is a key characteristic of borosilicate materials for both chemical vapor deposition and conventional melting processes. (2) For lithium niobate, a quantitative measure of Li concentration can differentiate congruent and stoichiometric compositions and any surface depletion in commercial wafers.
Blind acquisition of short burst with per-survivor processing

In this letter, the blind acquisition performance of PSP is discussed. Based on the theory of indistinguishable sequences (K.M. Chugg, 1998), modifications to conventional PSP are suggested that improve acquisition performance significantly. The effects of tree search and list-based algorithms on PSP are also discussed. In blind channel estimation, the performance of list-based algorithms is better than trellis-based algorithms and can be further enhanced using the proposed techniques. The blind acquisition techniques described here can be used for other applications like multi-user detection or space-time trellis codes
Quantum phase transition from an antiferromagnet to a spin liquid in a metal

We study quantum phase transitions from easy-plane antiferromagnetic metals to paramagnetic metals in Kondo-Heisenberg lattice systems. If the paramagnetic metal is a fractionalized Fermi liquid then the universal critical properties of the phase transition are unaffected for a weak Kondo coupling even when the Fermi surface intersects the magnetic zone boundary. This is in striking contrast to the conventional theory of phase transitions between paramagnetic and antiferromagnetic metals where any Kondo coupling is strongly relevant, and leads to a Landau-damped ``Hertz-Millis'' theory. The electron quasiparticle remains well defined in the quantum critical regime and the critical spin fluctuations only contribute subleading corrections to the various properties of conduction electrons.
The Influence of State Sales and Use Taxes on Manufacturers’ Capital Expenditures and Employment

This study investigates the relationship between the state sales and use tax (SUT) burden and manufacturing firms’ employment and capital expenditures for the period 1983–2006. Using an instrumental variable model, our results indicate that the SUT burden (i.e., the product between the sales and use tax rate and sales and use tax exemptions) on purchases of materials and machinery is related to changes in capital expenditures and employment, even after controlling for corporate income tax variables and other economic factors. The economic impact of this relationship is relatively small; however, the results have important policy implications in the present lean state budget environment, as state legislators must balance revenue needs with the desire to provide economic development incentives.
The Relationship between Molecular Gas Tracers and Kennicutt-Schmidt Laws

We provide a model for how Kennicutt-Schmidt (KS) laws, which describe the correlation between star formation rate and gas surface or volume density, depend on the molecular line chosen to trace the gas. We show that, for lines that can be excited at low temperatures, the KS law depends on how the line critical density compares to the median density in a galaxy's star-forming molecular clouds. High critical density lines trace regions with similar physical properties across galaxy types, and this produces a linear correlation between line luminosity and star formation rate. Low critical density lines probe regions whose properties vary across galaxies, leading to a star formation rate that varies superlinearly with line luminosity. We show that a simple model in which molecular clouds are treated as isothermal and homogenous can quantitatively reproduce the observed correlations between galactic luminosities in far-infrared and in the CO(1→0) and HCN(1→0) lines, and naturally explains why these correlations have different slopes. We predict that IR-line luminosity correlations should change slope for galaxies in which the median density is close to the line critical density. This prediction may be tested by observations of lines such as HCO+(1→0) with intermediate critical densities, or by HCN(1 → 0) observations of intensely star-forming high-redshift galaxies with very high densities. Recent observations by Gao et al. hint at just such a change in slope. We argue that deviations from linearity in the HCN(1→0)-IR correlation at high luminosity are consistent with the assumption of a constant star formation efficiency.
A Superstring Theory in Four Curved Space-Time Dimensions

Neveu-Schwarz-Ramond type heterotic and type-II superstrings in four dimensional curved space-time are constructed as exact $N=1$ superconformal theories. The tachyon is eliminated with a GSO projection. The theory is based on the N=1 superconformal gauged WZW model for the anti-de Sitter coset $SO(3,2)/SO(3,1)$ with integer central extension $k=5$. The model has dynamical duality properties in its space-time metric that are similar to the large-small ($R\rightarrow 1/R$) duality of tori. To first order in a $1/k$ expansion we give expressions for the metric, the dilaton, the Ricci tensor and their dual generalizations. The curvature scalar has several singularities at various locations in the 4-dimensional manifold. This provides a new singular solution to Einstein's equations in the presence of matter in four dimensions. A non-trivial path integral measure which we conjectured in previous work for gauged WZW models is verified.
Crystal Structures of GCN2 Protein Kinase C-terminal Domains Suggest Regulatory Differences in Yeast and Mammals

In response to amino acid starvation, GCN2 phosphorylation of eIF2 leads to repression of general translation and initiation of gene reprogramming that facilitates adaptation to nutrient stress. GCN2 is a multidomain protein with key regulatory domains that directly monitor uncharged tRNAs which accumulate during nutrient limitation, leading to activation of this eIF2 kinase and translational control. A critical feature of regulation of this stress response kinase is its C-terminal domain (CTD). Here, we present high resolution crystal structures of murine and yeast CTDs, which guide a functional analysis of the mammalian GCN2. Despite low sequence identity, both yeast and mammalian CTDs share a core subunit structure and an unusual interdigitated dimeric form, albeit with significant differences. Disruption of the dimeric form of murine CTD led to loss of translational control by GCN2, suggesting that dimerization is critical for function as is true for yeast GCN2. However, although both CTDs bind single- and double-stranded RNA, murine GCN2 does not appear to stably associate with the ribosome, whereas yeast GCN2 does. This finding suggests that there are key regulatory differences between yeast and mammalian CTDs, which is consistent with structural differences.
A Tribute to Bill Kruskal

Bill Kruskal was a dedicated citizen of the Univer sity of Chicago, of the broader statistical community and of the country. It is difficult to convey fully Bill's commitment to and contributions to the community life of the University. The University of Chicago, unusual among American universities, believes that the maintenance and enhancement of a scholarly community is part of its mission. Maintaining a true scholarly community is difficult and rests heavily on those who are willing to commit some of their time and energy to the betterment of the community. Bill was an extraordinarily good cit izen, He chaired a number of faculty committees that dealt with some of the most delicate issues of univer sity life, notably the Committee on Appointment In equities; he was a member of the Council of the Uni versity Senate and of the Committee of the Council; he served as chairman of the Statistics Department and in a bold move, for he was not a member of its faculty, served as dean of the Social Sciences Division for two terms, as well as serving as dean pro tempore during the Harris School's inaugural year. This concern for the University extended to the prac tices of the library. When he could not find a particular issue of a Census Bureau serial publication, but instead found a note taped in the bound volume saying that the library had discarded number 8 at the request of the Government Printing Office because the report had too many mistakes, he wrote in some indignation, "How could our library discard a document that ipso facto held such sociological, ethical, statistical and historical interest? Horrors. ... After all when the Russians send us replacement pages for their great encyclopedia, we add them but keep the old ones unlike (I think) the li brarians in Moscow, Minsk and Leningrad." Bill had a passionate commitment to the health of the federal statistical system and to the intelligent use of statistics in the formation and implementation of public policy. It was this commitment to the federal statistical
Evidence of chaos in slab avalanching

We present evidence that slab avalanching is a chaotic process. We studied a set of 8062 avalanches running on more than 140 paths at Mammoth Mountain, CA between November 1982 and May 2002. Cumulative crown size distributions over the entire mountain and on individual paths are scale invariant and appear to form a multifractal set; chaotic systems often exhibit such statistics. We examine avalanche control data from 416 days on a single path over the same 20-year period and reconstruct the phase space portrait and resulting attractor for crown size. Three independent tests indicate the time series is deterministic: plateauing of the correlation dimension with increasing embedding dimension, the correlation dimension of the attractor compared against the correlation dimensions of surrogate sets of random data and a measure of trajectory alignments for neighboring points in phase space. These tests, coupled with non-periodic and non-intersecting phase space trajectories, suggest the attractor is a strange attractor and that slab avalanching is a chaotic process. We examine and reject two likely non-chaotic sources of crown size scaling: new snow layering and topography. We discuss three factors that might contribute to chaotic avalanche behavior: scaling, the deposition and evolution of snow layers and the mechanics of slab release. If slab avalanching is a chaotic process, then subresolution processes and system sensitivity to initial conditions preclude purely physical models of long-term slab evolution and release.
Design of an interactive matrix calculator

MATLAB is an interactive computer program that serves as a convenient "laboratory" for computations involving matrices. It provides easy access to matrix software developed by the LINPACK and EISPACK projects [1--3]. The capabilities range from standard tasks such as solving simultaneous linear equations and inverting matrices, through symmetric and nonsymmetric eigenvalue problems, to fairly sophisticated matrix tools such as the singular value decomposition.
A Petri-net coordination model for an intelligent mobile robot

A Petri net model of the coordination level of an intelligent mobile robot system (IMRS) is presented. The purpose of this model is to specify the integration of the individual efforts on path planning, supervisory motion control, and vision system that are necessary for the autonomous operation of a mobile robot in a structured dynamic environment. This is achieved by analytically modeling the various units of the system as Petri net transducers and explicitly representing the task precedence and information dependence among them. The model can be used to simulate the task processing and evaluate the efficiency of operations and the responsibility of decisions in the coordination level of the intelligent mobile robot system. Some simulation results of the task processing and learning are presented. >
Finite element analysis of inelastic structures.

Differential stress-strain relationships are used to generate a system of simultaneous firstorder differential force-displacement equations which are integrated numerically to obtain the stresses, strains, and displacements in inelastic structures. For the biaxially stressed element, the concept of isotropic hardening and a generalized stress are used to evaluate an effective modulus and Poisson's ratio, which vary continuously from their initial values during elastic straining action to their asymptotic values during intense plastic straining action. The surface of plasticity for this element closely approximates the von Mises surface when the generalized stress is set equal to the von Mises stress and the strain distribution is essentially identical to that obtained by the Prandtl-Reuss incremental flow theory. The analysis of the MIT shear lag structure is presented to demonstrate the applicability of the method to systems of practical size and interest. Nomenclature A = equilibrium matrix B = compatibility matrix C = stress-strain matrix C = differential stress matrix E = Young's modulus Et = tangent modulus Es = secant modulus K — stiffness matrix K = differential stiffness matrix P = applied load parameter u = element nodal displacements X = element nodal forces X = load constant n = Poisson's ratio fjLt = tangent Poisson's. ratio Us = secant Poisson's ratio e = strain a- = normal stress <?e = effective or generalized stress T = shear stress fi = stress-strain curve shape parameter
Dichotomy in short superconducting nanowires: Thermal phase slippage vs. Coulomb blockade

Quasi-one-dimensional superconductors or nanowires exhibit a transition into a nonsuperconducting regime, as their diameter shrinks. We present measurements on ultrashort nanowires ( 40–190 nm long) in the vicinity of this quantum transition. Properties of all wires in the superconducting phase, even those close to the transition, can be explained in terms of thermally activated phase slips. The behavior of nanowires in the nonsuperconducting phase agrees with the theories of the Coulomb blockade of coherent transport through mesoscopic normal metal conductors. Thus it is concluded that the quantum transition occurs between two phases: a "true superconducting phase" and an "insulating phase". No intermediate, "metallic" phase was found.
Experimental signatures of localization in Langmuir wave turbulence

Abstract Features in certain laser-plasma and ionospheric experiments are identified with the basic properties of Langmuir wave turbulence. Also, a model of caviton nucleation is presented which leads to certain novel scaling predictions.
Integrity monitoring in WLAN positioning systems

Indoor Positioning Systems using WLANs have become very popular in recent years. These systems are spawning a new class of applications like activity recognition, surveillance, context aware computing and location based services. While Global Positioning System (GPS) is the natural choice for providing navigation in outdoor environment, the urban environment places a significant challenge for positioning using GPS. The GPS signals can be significantly attenuated, and often completely blocked, inside buildings or in urban canyons. As the performance of GPS in indoor environments is not satisfactory, indoor positioning systems based on location fingerprinting of WLANs is being suggested as a viable alternative. The Indoor WLAN Positioning Systems suffer from several phenomena. One of the problems is the continual availability of access points, which directly affects the positioning accuracy. Integrity monitoring of WLAN localization, which computes WLAN positioning with different sets of access points is proposed as a solution for this problem. The positioning accuracy will be adequate for the sets which do not contain faulty or the access points which are offline, while the sets with such access points will fail and they will report random and inaccurate results. The proposed method identifies proper sets and identifies the rogue access points using prediction trajectories. The combination of prediction and correct access point set selection provides a more accurate result. This paper discusses about integrity monitoring method for WLAN devices and followed by how it monitors and developing the application on mobile platforms.
Calibration technique for monoplane stereo x-ray system in imaging guidance

A simple calibration technique for monoplane stereo x-ray imaging system in stereotactic breast biopsy was developed. According to the principle of perspective projection, a monoplane stereo imaging model was established, the geometric parameters for the purpose of 3D point reconstruction were described. The parameters are source- imager-distance and the x-ray tube positions with respect to the imaging receptor. These parameters are calculated using a phantom consisting of three radio-opaque calibration lines of known length and orientation in 3D space and applying the concepts of similar triangles. Two line segments are parallel to the image detector and another one is perpendicular to the image detector. The computer simulations and experiments were carried out which determines these parameters for our CCD based monoplane stereotactic prototype. The results were in agreement with the theoretical prediction. This calibration technique is applied to the stereo imaging system where the final calibration error is within 1.5 percent. The method is simple and reliable. One promising application of this technique for the calibration lies in digital mammography imaging guidance, but applications in other forms of radiographic imaging are possible also.
A convenient synthesis of carbonyl chloride fluoride

Abstract An improved method for the synthesis of COClF under mild conditions is reported. Pure COClF can be isolated in essentially quantitative yield from the decomposition of the oxygen-bridged COCl2·SbF5 donor–acceptor adduct at room temperature in a dynamic vacuum.
DNA hybridization using surface plasmon-coupled emission

We described a new approach to measuring DNA hybridization using surface plasmon-coupled emission (SPCE). This phenomenon occurs for fluorophores within few hundreds of nanometers of a thin metal film on a glass substrate, in our case a 50 nm thick silver film. Excited fluorophores coupled with the surface plasmons in the metal resulting in directional emission through the glass substrate. We studied the emission of Cy3-labeled DNA oligomers bound to complementary unlabeled biotinylated-oligomers, which were bound to the metal surface via a streptavidin-BSA monolayer. Hybridization resulted in directional emission of Cy3-DNA into the prism. Additionally, the use of SPCE resulted in suppression of interfering emission from non-complementary Cy5-DNA oligomers due to weaker coupling of the more distant fluorophores with the surface plasmons. A large fraction of the total potential emission can couple to the surface plasmon resulting in improved sensitivity. We expect SPCE to have numerous applications to nucleic acid analyses.
Criminal Investigation Enforcement Activities and Taxpayer Noncompliance

This paper tests empirically whether measurable activities of the IRS Criminal Investigation Division (CI) affect taxpayer compliance. The analysis is based on a state-level cross-section for the time period from 1988 through 2001. First, I find that CI activities have a measurable and significant effect on voluntary compliance. Second, I conclude that the mix of sentenced cases (tax and money laundering) is not a significant determinant of tax compliance. Third, media attention shows some weak evidence of increasing compliance, at least among money laundering cases. Fourth, I find that incarceration and probation (rather than fines) have the most influence on taxpayers. Simulations using the estimated models show that the direct effect of doubling the audit rate on assessed tax collections (reported amounts and additional taxes and penalties) is $18.7 billion. Doubling CI tax and money laundering sentences is forecast to increase assessed collections by $16.7 billion. I estimate the general deterrence or spillover effects from either audit or CI activities to be approximately 94 percent.
The Chemistry and Biochemistry of Heme c: Functional Bases for Covalent Attachment

A discussion of the literature concerning the synthesis, function, and activity of heme c-containing proteins is presented. Comparison of the properties of heme c, which is covalently bound to protein, is made to heme b, which is bound noncovalently. A question of interest is why nature uses biochemically expensive heme c in many proteins when its properties are expected to be similar to heme b. Considering the effects of covalent heme attachment on heme conformation and on the proximal histidine interaction with iron, it is proposed that heme attachment influences both heme reduction potential and ligand-iron interactions.
Every list-decodable code for high noise has abundant near-optimal rate puncturings

We show that any q-ary code with sufficiently good distance can be randomly punctured to obtain, with high probability, a code that is list decodable up to radius 1 --- 1/q --- e with near-optimal rate and list sizes. Our results imply that "most" Reed-Solomon codes are list decodable beyond the Johnson bound, settling the longstanding open question of whether any Reed Solomon codes meet this criterion. More precisely, we show that a Reed-Solomon code with random evaluation points is, with high probability, list decodable up to radius 1 --- e with list sizes O(1/e) and rate Ω(e). As a second corollary of our argument, we obtain improved bounds on the list decodability of random linear codes over large fields. Our approach exploits techniques from high dimensional probability. Previous work used similar tools to obtain bounds on the list decodability of random linear codes, but the bounds did not scale with the size of the alphabet. In this paper, we use a chaining argument to deal with large alphabet sizes.
Testing cold dark matter models using Hubble flow variations

COBE-normalized flat (matter plus cosmological constant) and open cold dark matter (CDM) models are tested by comparing their expected Hubble flow variations and the observed variations in a Type Ia supernova sample and a Tully--Fisher cluster sample. The test provides a probe of the CDM power spectrum on scales of 0.02h Mpc-1≲ k≲ 0.2h Mpc-1, free of the bias factor b. The results favour a low matter content universe, or a flat matter-dominated universe with a very low Hubble constant and/or a very small spectral index nps, with the best fits having Ο0∼ 0.3 to 0.4. The test is found to be more discriminative to the open CDM models than to the flat CDM models. For example, the test results are found to be compatible with those from the X-ray cluster abundance measurements at smaller length-scales, and consistent with the galaxy and cluster correlation analysis of Peacock & Dodds at similar length-scales, if our universe is flat; but the results are marginally incompatible with the X-ray cluster abundance measurements if our universe is open. The open CDM results are consistent with that of Peacock & Dodds only if the matter density of the universe is less than about 60 per cent of the critical density. The shortcoming of the test is discussed, so are ways to minimize it.
Navier-Stokes calculations for unsteady three-dimensional vortical flows in unbounded domains

Finite-difference Navier-Stokes calculations for unsteady, three-dimensional, incompressible, viscous flows induced by initial vorticity distributions are presented and discussed in this paper. The initial vorticity distributions are assumed to be embedded in a flow field of infinite extent that is quiescent at infinity. These vorticity distributions are typical of vortex rings and other closed vortical tubes or structures. Such structures are important elements in fluid flows such as jets, atmospheric convection and the far-field wakes of aircraft; studies of their interaction may aid in an understanding of complex fluid flows. The calculations employ a method recently proposed by Ting to approximate the infinite-domain boundary value problem with a finite boundary computational domain, and this method is shown to yield accurate three-dimensional results for reasonable expenditures of computer time. Because of the efficiency of the boundary condition technique and the resulting Navier-Stokes code, a 16-bit minicomputer with virtual memory was capable of performing the calculations for the unsteady motion of two obliquely colliding vortex rings. The results of these calculations are presented in the paper.
Mechanics, Planning, and Control for Tapping

We present analysis and experimental demonstration of manipulation by tapping. Our problem domain is positioning planar parts on a support surface by a sequence of taps; each tap imparts some initial velocities to the object, which then slides until it comes to rest due to friction. We formulate the mechanics of tapping for circular axisymmetric objects, show how to plan a single tap and a sequence of taps to reach a goal configuration, and present feedback control methods to robustly accomplish positioning tasks. With these methods, we have experimentally demonstrated positioning tasks using tapping, including high-precision positioning tasks in which the object is positioned more precisely than the tapping actuator. We show stability and sensitivity analysis in support of these results.
The Ising model on a dynamically triangulated disk with a boundary magnetic field

Abstract We use Monte Carlo simulations to study a dynamically triangulated disk with Ising spins on the vertices and a boundary magnetic field. For the case of zero magnetic field we show that the model possesses three phases. For one of these the boundary length grows linearly with disk area, while the other two phases are characterized by a boundary whose size is on the order of the cut-off. A line of continuous magnetic transitions separates the two small boundary phases. We determine the critical exponents of the continuous magnetic phase transition and relate them to predictions from continuum 2-d quantum gravity. This line of continuous transitions appears to terminate on a line of discontinuous phase transitions dividing the small boundary phases from the large boundary phase. We examine the scaling of bulk magnetization and boundary magnetization as a function of boundary magnetic field in the vicinity of this tricritical point.
The Near-Ultraviolet Continuum of Late-Type Stars

Analyses of the near-ultraviolet continuum of late-type stars have led to controversial results regarding the performance of state-of-the-art model atmospheres. The release of the homogeneous International Ultraviolet Explorer (IUE) final archive and the availability of the high-accuracy Hipparcos parallaxes provide an opportunity to revisit this issue, as accurate stellar distances make it possible to compare observed absolute fluxes with the predictions of model atmospheres. The near-UV continuum is highly sensitive to Teff and [Fe/H], and once the gravity is constrained from the parallax, these parameters may be derived from the analysis of low-dispersion, long-wavelength (2000–3000 A) IUE spectra for stars previously studied by Alonso, Arribas, & Martinez-Roger using the Infrared Flux Method (IRFM). A second comparison is carried out against the stars spectroscopically investigated by Gratton, Carretta, & Castelli. It is shown that there is a good agreement between Teff values obtained from the IRFM and those from the near-UV continuum, and a remarkable correspondence between observed and synthetic fluxes for stars with 4000 K ≤ Teff ≤ 6000 K of any metallicity and gravity. These facts suggest that model atmospheres provide an adequate description of the near-UV continuum forming region and that the opacities involved are essentially understood.
Transition between nuclear and quark–gluon descriptions of hadrons and light nuclei

We provide a perspective on studies aimed at observing the transition between hadronic and quark-gluonic descriptions of reactions involving light nuclei. We begin by summarizing the results for relatively simple reactions such as the pion form factor and the neutral pion transition form factor as well as that for the nucleon and end with exclusive photoreactions in our simplest nuclei. A particular focus will be on reactions involving the deuteron. It is noted that a firm understanding of these issues is essential for unravelling important structure information from processes such as deeply virtual Compton scattering as well as deeply virtual meson production. The connection to exotic phenomena such as color transparency will be discussed. A number of outstanding challenges will require new experiments at modern facilities on the horizon as well as further theoretical developments.
Rare-Event Simulation for Many-Server Queues

We develop rare-event simulation methodology for the analysis of loss events in a many-server loss system under the quality-driven regime, focusing on the steady-state loss probability (i.e., fraction of lost customers over arrivals) and the behavior of the whole system leading to loss events. The analysis of these events requires working with the full measure-valued process describing the system. This is the first algorithm that is shown to be asymptotically optimal, in the rare-event simulation context, under the setting of many-server queues involving a full measure-valued representation.
The costs of ignoring high-order correlations in populations of model neurons

Investigators debate the extent to which neural populations use pair-wise and higher-order statistical dependencies among neural responses to represent information about a visual stimulus. To study this issue, three statistical decoders were used to extract the information in the responses of model neurons about the binocular disparities present in simulated pairs of left-eye and right-eye images: (1) the full joint probability decoder considered all possible statistical relations among neural responses as potentially important; (2) the dependence tree decoder also considered all possible relations as potentially important, but it approximated high-order statistical correlations using a computationally tractable procedure; and (3) the independent response decoder, which assumed that neural responses are statistically independent, meaning that all correlations should be zero and thus can be ignored. Simulation results indicate that high-order correlations among model neuron responses contain significant information about binocular disparities and that the amount of this high-order information increases rapidly as a function of neural population size. Furthermore, the results highlight the potential importance of the dependence tree decoder to neuroscientists as a powerful but still practical way of approximating high-order correlations among neural responses.
DAFT: Decoupled Acyclic Fault Tolerance

Higher transistor counts, lower voltage levels, and reduced noise margin increase the susceptibility of multicore processors to transient faults. Redundant hardware modules can detect such faults, but software techniques are more appealing for their low cost and flexibility. Recent software proposals have not achieved widespread acceptance because they either increase register pressure, double memory usage, or are too slow in the absence of hardware extensions. This paper presents DAFT, a fast, safe, and memory efficient transient fault detection framework for commodity multicore systems. DAFT replicates computation across multiple cores and schedules fault detection off the critical path. Where possible, values are speculated to be correct and only communicated to the redundant thread at essential program points. DAFT is implemented in the LLVM compiler framework and evaluated using SPEC CPU2000 and SPEC CPU2006 benchmarks on a commodity multicore system. Evaluation results demonstrate that speculation allows DAFT to improves the performance of software redundant multithreading by 2.17× with no degradation of fault coverage.
Irregular Magnetic Fields and the Far-Infrared Polarimetry of Dust Emission from Interstellar Clouds

The polarized thermal radiation at far-infrared and submillimeter wavelengths from dust grains in interstellar clouds with irregular magnetic fields is simulated. The goal is to determine to what degree irregularity in the magnetic fields can be consistent with the observation that the maps of the polarization vectors are relatively ordered. Detailed calculations are performed for the reduction in the fractional polarization and the dispersion in position angles as a function of the ratio of the irregular to the uniform magnetic field and as a function of the relevant dimensions measured in correlation lengths of the field. We show that the polarization properties of quiescent clouds and of star-forming regions are consistent with Kolmogorov-like turbulent magnetic fields that are comparable in magnitude to the uniform component of the magnetic fields. If the beam size is much smaller than the correlation length, Lcorr, of the fields, the calculated percentage polarization, p, decreases to an asymptotic value when the number of correlation lengths, Ncorr, through the cloud exceeds a few × 10. For these values of Ncorr, the dispersion in the position angles, σα, is still appreciable, decreasing to only ~20°. However, when the finite size of a telescope beam is taken into account the asymptotic value of p is reached for fewer correlation lengths (smaller Ncorr) because of averaging over the beam; σα becomes much smaller and is consistent with the observational data. The smoothing of the polarization properties due to the combined effect of the thickness of the cloud and the finite size of the beam can be described by a single variable that we designate as the generalized number of correlation lengths. In addition, we study various factors that may contribute to the decrease in the linear polarization percentage with increasing intensity that is observed at submillimeter and far-infrared wavelengths in many, although not all, dark clouds (the "polarization hole" effect). Depolarization due to a density cutoff in the polarizing effect of dust, thermalization, and correlations between the density and the properties of the magnetic field are considered.
2006 IODC illumination design problem

For the first time, the IODC conference included a contest on Illumination Design along with the traditional Lens Design problem. The proposed problem aimed to find the best solution for a flux coupling problem with high-efficiency and close to the source to target etendue-matching situation. A total of eight valid solutions were submitted showing a variety of approaches, including rotational reflective optics, free-form surfaces, square-to-cross light pipe converters, projection lenses (from singlets to spherical symmetric non-homegeneous refractive index ones). The winning solution was submitted by Bill Cassarly.
Extending Cutoff Resolvent Estimates via Propagation of Singularities

We use a gluing method developed in joint work with Andras Vasy to show that polynomially bounded cutoff resolvent estimates at the real axis imply the same estimates, up to a constant factor, in a...
Ferroelectric polarization reversal in single crystals

Research on the reversal of polarization in ferroelectric crystals is reviewed. Particular attention is given to observation methods for polarization reversal, BaTiO3 polarization reversal, crystal thickness dependence of polarization reversal, and domain wall movement during polarization reversal in TGS.
Extended neck dissection

The most important prognostic factor in the management of head and neck cancer is the presence of nodal metastasis. Nodal metastasis generally decreases survival by almost 50%. The classical surgical procedure for cervical metastasis has been radical neck dissection for almost 75 years. There has been a paradigm shift towards modified neck dissections and preserving vital structures, especially the accessory nerve. Occasionally, patients may present with advanced metastatic disease in the neck requiring extended neck dissection—removal of additional structures such as skin, platysma, hypoglossal nerve, posterior belly of the digastric muscle, vagus nerve, and occasionally carotid artery. There are select indications for extended neck dissection and with postoperative radiation therapy satisfactory local control can be achieved. Every surgeon involved in head and neck surgery should be familiar with the procedure of extended neck dissection, its operative technique and prognostic implications.
Total synthesis of kinamycins C, F, and J.

The kinamycins are a series of naturally occurring compounds endowed with intriguing molecular architectures and potent biological properties, including antibiotic and antitumor activities. These novel diazofluorene-containing compounds defied chemical synthesis since their initial disclosure by Omura et al. in 1970 until the first total synthesis of kinamycin C by Porco et al. in late 2006, and of methyl-kinamycin C by the Kumamoto−Ishihawa group in 2007. We now report our enantioselective total synthesis of kinamycins C, F, and J through a convergent strategy that is both enantioselective and expedient.
Transverse preputial Island flap technique for repair of severe hypospadias

The glans channel technique combined with the use of a transverse preputial island flap to create a neourethra is outlined for one-stage repair of severe hypospadias.
Tiananmen Square 1989: the view from financial markets

This article examines the effects of the Tiananmen Square incident on Hong Kong stock prices, which fell by more than 22% on the first day of trading after the event. Notwithstanding the expected negative across-the-board impact, we find some partial protection from the worst of the negative effects enjoyed by investors in utility stocks and companies with ownership ties to mainland China. Whereas some of the harder hit sectors enjoyed some degree of catching up after the first 2 months since the crisis, continued underperformance is seen for the hotel and property sectors throughout the empirical testing. The most domestically focused sectors therefore were also the ones that experienced the most lasting damage.
Total synthesis of 8,14-dihydromorphinandienone alkaloids.

A collective synthesis of 8,14-dihydronorsalutaridine, 8,14-dihydrosalutaridine, norisosinomenine, and isosinomenine is reported. The strategy provides direct access to the correct oxidation level of the products. The combination of an organocatalyst guanidine superbase, a tertiary amine base, and a dehydrating agent was necessary for the successful Henry–Michael–dehydration cascade to form the phenanthrene motif. The required selective aliphatic nitro reduction could only be achieved under heterogeneous transfer–hydrogenation conditions.
Synthesis of Optically Pure 2-Azido-1-arylethanols with Isolated Enzymes and Conversion to Triazole-Containing β-Blocker Analogues Employing Click Chemistry

Both antipodes of 2-azido-1-arylethanols were synthesized with excellent optical purity via enzymatic reduction of the corresponding α-azidoacetophenone derivatives catalyzed by a recombinant carbonyl reductase from Candida magnoliae (CMCR) or an alcohol dehydrogenase from Saccharomyces cerevisiae (Ymr226c). This provides an effective route to this class of important compounds in optically pure form. (S)-2-Azido-1-(p-chlorophenyl)ethanols reacted with alkynes employing click chemistry to afford high yields of optically pure triazole-containing β-adrenergic receptor blocker analogues with potential biological activity.
Helicity of Neutrinos

A combined analysis of circular polarization and resonant scattering of gamma rays following orbital electron capture measures the helicity of the neutrino. A measurement was carried out with Eu/sup 152/ which decays by orbital electron capture. Assuming the most plausible spin-parity for this isomer compatible with its decay scheme, 0-1, it was found that the neutrino was ''left handed,'' and had negative helicity. (A. C.)