cssi/SciSciGPT-SciSciNet huggingface dataset:
STAR FORMATION RATE DISTRIBUTIONS: INADEQUACY OF THE SCHECHTER FUNCTION

In this paper, we posit that galaxy luminosity functions (LFs) come in two fundamentally different types depending on whether the luminosity traces galaxy stellar mass or its current star formation rate (SFR). Mass function types reflect the older stars and therefore the stellar mass distribution, while SFR function types arise from the young stars and hence the distribution of SFRs. Optical and near-infrared LFs are of the mass function type and are well fit by a Schechter function (power law with an exponential cutoff at the bright end). In contrast, LFs of the SFR function type are of a different form, one that cannot be adequately described by a Schechter function. We demonstrate this difference by generating SFR distributions for mock samples of galaxies drawn from a Schechter stellar mass distribution along with established empirical relations between the SFR and stellar mass. Compared with the Schechter function, SFR distributions have a shallower decline at the bright end, which can be traced to the large intrinsic scatter of SFRs at any given stellar mass. A superior description of SFR distributions is given by the "Saunders" function, which combines a power law with a Gaussian at the high end. We show that the Schechter-like appearance of UV and Hα LFs, although they are LFs of SFR function type, results when luminosities are not corrected for dust, or when average statistical corrections are used because individual attenuation measurements are not available. We thus infer that the non-Schechter form of the far-IR LFs is a true reflection of the underlying SFR distribution, rather than the purported artifact of active galactic nucleus contamination.
The Viking Orbiter Visual Imaging Subsystem

Two Viking spacecraft each consisting of an Orbiter and a Lander are on trajectories toward Mars with arrival dates in June and August 1976. A Visual Imaging Subsystem consisting of two slow-scan television cameras forms part of the scientific payload of each Orbiter. These cameras will be used to evaluate the potential landing sites on Mars and to conduct other scientific investigations of the planet. The camera system described in this paper was subjected to an extensive test and calibration program prior to launch. Based on this calibration and subsequent analyses, absolute photometric accuracies of 8.0% may be achieved. Surface resolution exceeding 100 meters will be achieved from the periapsis portion of the Viking orbits. The inherent geometric accuracies of the Orbiter cameras supersede those of previous planetary missions. The analyses of images acquired during the cruise phase of the mission confirms that the cameras have survived the rigors of launch and are performing in a manner consistent with the prelaunch calibrations.
Synthesis of 2-substituted benzimidazole-5-carbamates as potential antifilarial agents

A number of 2,5-disubstituted benzimidazoles have been prepared from 2-benzyl-5-nitrobenzimidazole (5) and 2-p-fluorobenzyl-5-nitrobenzimidazole (6), and evaluated as potential antifilarial agents. None of the compounds prepared in this study have demonstrated any significant antifilarial activity.
Numerical Solution of Supersonic Viscous Flow over Blunt Delta Wings

A general parabolized Navier-Stokes code has been developed to compute the steady supersonic viscous flow around arbitrary body shapes at high angles of attack. A nonorthogonal three-dimensional coordinate frame permits the code to march with solution surfaces which are the most appropriate. The code has been used to calculate the laminar flow over a slab delta wing with 70 deg sweep at angles of attack up to 41.5 deg and Mach numbers of 6.8 and 9.6. The computed shock shapes, surface pressures and heat transfer coefficients are compared with experiment and show agreement.
Synthesis of complex allylic esters via C-H oxidation vs C-C bond formation.

A highly general, predictably selective C−H oxidation method for the direct, catalytic synthesis of complex allylic esters is introduced. This Pd(II)/sulfoxide-catalyzed method allows a wide range of complex aryl and alkyl carboxylic acids to couple directly with terminal olefins to furnish (E)-allylic esters in synthetically useful yields and selectivities (16 examples, E/Z ≥ 10:1) and without the use of stoichiometric coupling reagents or unstable intermediates. Strategic advantages of constructing allylic esters via C−H oxidation vs C−C bond-forming methods are evaluated and discussed in four “case studies”.
The Variation in the Resistance of Carbon and Graphite with Temperature

Change of resistance of carbon and graphite with temperature, ---190\ifmmode^\circ\else\textdegree\fi{} to 2000\ifmmode^\circ\else\textdegree\fi{}C.---For the higher temperatures the specimens were kept in vacuum and heated by a current passed through them, temperatures being measured optically. Several specimens of untreated carbon filament made from braided silk, showed a resistance decreasing linearly with temperature, the ratio to the resistance at room temperature being equal to $1.07\ensuremath{-}.000225T$, where $T$ is temperature absolute. In the case of a metallized filament ("Gem"), the resistance decreased to a minimum for 400\ifmmode^\circ\else\textdegree\fi{}C and then increased steadily. Acheson graphite, purified somewhat by heating, showed minimum resistance at about 600\ifmmode^\circ\else\textdegree\fi{} and then increased linearly. These results do not fit any law which has yet been proposed. Effect of air. Graphite in the presence of air at about 1/4 atm. pressure had a resistance at 500\ifmmode^\circ\else\textdegree\fi{}C about 4 per cent lower than in a vacuum. This effect decreased with temperature, being absent at room temperature.Change of length of carbon rod at about 2200\ifmmode^\circ\else\textdegree\fi{}C.---An increase in length was observed, which resulted in permanently bending the specimen.
Pixel Lensing Search for Bright Microlensing Events and Variables in the Galactic Bulge

We describe a new method to search for gravitational microlensing toward the Galactic bulge that employs a small camera rather than a conventional telescope and probes new regions of parameter space. The small aperture (~65 mm) permits detection of stellar flux variations corresponding to magnitudes 7 I 16, while current searches are restricted by saturation to I 15. The large pixel size (~10'') and ~(6 deg)2 field of view allows observation of the entire bulge with a few pointings. With this large pixel size (and with the even larger 30'' point-spread function [PSF] that we advocate) most bulge stars are unresolved, so one is in the regime of pixel lensing: microlensing and other forms of stellar variation are detected from the difference of pixel counts in successive images. We identify three principal uses of such a search. First, the observations are analogous to normal pixel lensing observations of the bulge of M31 but are carried out under conditions where the detected events can be followed up in detail. This permits crucial checks on the systematics of the M31 searches. Second, the search gives a complete inventory of bright bulge variables. Third, extreme microlensing events (EMEs) can be found in real time. EMEs are events with maximum magnifications Amax ~ 200 which, if they were observed intensively from two observatories, could yield the mass, distance, and speed of the gravitational lens. The instrumentation required to carry out the observations is inexpensive. The observations could be made in parallel with existing microlensing searches and/or follow-up observations. The data reduction is much simpler than in ordinary pixel lensing because the PSF can be fixed by the optics and so does not vary with atmospheric conditions.
Properties of generalized Forchheimer flows in porous media

We consider generalized Forchheimer flows for slightly compressible fluids and study the initial boundary value problem for the degenerate parabolic equation with time dependent boundary condition. We estimate the L∞-norm of the pressure and derive some other estimates. We show that the solutions and its gradient depend continuously on the initial and boundary data and coefficients of the Forchheimer polynomials. De Giorgi and Ladyzhenskaya–Uraltseva iteration techniques are used. Bibliography: 36 titles.
The same face of the two Smiths: Adam Smith and Vernon Smith

Abstract Going from personal to impersonal exchange seems to be a relevant feature that allows humans to develop complex societies and grow prosperous. Adam Smith's idea of moral imagination, embodied in the impartial spectator and achieved through sympathy, may integrate and complement today's evolutionary biology and experimental economic explanations, providing the missing key as to how we generate and internalize those rules of conduct that promote fair and cooperative behaviors.
Investigation of the Possible Third Image and Mass Models of the Gravitational Lens PMN J1632–0033

We present multifrequency VLBA observations of PMN J1632-0033, one of the few gravitationally lensed quasars suspected of having a central "odd" image. The central component has a different spectral index than the two bright quasar images. Therefore, either the central component is not a third image, and is instead the active nucleus of the lens galaxy, or else it is a third image whose spectrum is inverted by free-free absorption in the lens galaxy. In either case, we have more constraints on mass models than are usually available for a two-image lens, especially when combined with the observed orientations of the radio jets of the two bright quasars. If there is no third quasar image, the simplest permitted model is a singular isothermal sphere in an external shear field: β = 2.05 (2 σ), where ρ(r) ∝ r-β. If the central component is a third image, a hypothesis that can be tested with future high-frequency observations, then the density distribution is only slightly shallower than isothermal: β = 1.91 ± 0.02 (2 σ). We also derive limits on the size of a constant-density core, and the break radius and exponent of an inner density cusp.
The ALARA (As Low As Reasonably Achievable) Concept in Pediatric Interventional and Fluoroscopic Imaging: Striving to Keep Radiation Doses as Low as Possible during Fluoroscopy of Pediatric Patients—A White Paper Executive Summary

ALARA represents a practice mandate adhering to the principle of keeping radiation doses to patients and personnel As Low As Reasonably Achievable. This concept is strongly endorsed by the Society for Pediatric Radiology, particularly in the use of procedures and modalities involving higher radiation doses such as CT and fluoroscopic examinations of pediatric patients. There is no doubt that medical imaging, which has undergone tremendous technological advances in recent decades, is integral to patient care. However, these technological advances generally precede the knowledge of end-users concerning the optimal use and correct operation of the resulting imaging equipment, and such knowledge is essential to minimizing potential risks to the patients. Current imaging methods must be optimized for radiation dose reduction in pediatric patients who might be as much as ten times more radiosensitive than adults. Unlike straightforward radiographic examinations, radiation dose to the patient during fluoroscopy is dependent on the operator’s training, experience with the fluoroscope, and efficiency in completing a diagnostic study. The range of pediatric radiation doses from fluoroscopy is wide because this examination is performed not only by pediatric radiologists but also by general radiologists who occasionally care for children, interventional cardiologists, gastroenterologists, urologists and others. Thus, a venue where multidisciplinary interaction by this variety of operators can occur serves to improve pediatric patient care. The third ALARA conference organized by the Society for Pediatric Radiology was held in Orlando, Fla., on 11–12 February 2006. It was co-sponsored by the Office of Rare Diseases and the National Cancer Institute of the National Institutes of Health (NCI/NIH). The conference was funded by unrestricted educational grants from three manufacturers of fluoroscopic and interventional equipment (GE, Philips, Siemens) and financial support from the Society for Pediatric Radiology and NCI/NIH. The 22 faculty members consisted of 8 pediatric radiologists, 5 medical physicists, 3 pediatric subspecialists, 3 industry speakers, and 3 radiation epidemiology researchers. A diverse cadre of 74 pediatric radiologists, medical physicists, radiologic technologists, researchers, pediatric subspecialists and vendors met to examine the risk of radiation exposure from fluoroscopic and interventional procedures, identify means by which to reduce ionizing radiation exposure, and explore future technologic modifications that could optimize imaging while further reducing radiation exposures.
NONLINEAR LANDAU DAMPING IN COLLISIONLESS PLASMA AND INVISCID FLUID

The long-time nonlinear evolution of generic initial perturbations in stable Vlasov plasma and two-dimensional (2D) ideal fluid is studied. Even without dissipation, these systems relax to new steady states (Landau damping). The asymptotic damping laws are found to be algebraic, such as ${t}^{\ensuremath{-}1}$ for 1D plasma potential, or ${t}^{\ensuremath{-}5/2}$ for evolving stream function in a flow with nonvanishing shear. The rate of the relaxation is fast so that phase-space/fluid-element displacement in certain directions is uniformly small, implying that decaying Vlasov and 2D fluid turbulences are not ergodic.
Solar radio bursts of spectral type II, coronal shocks, and optical coronal transients

The association of solar radio bursts of spectral type II and coronal shocks with solar flare ejecta observed in Hα, the green coronal line, and white-light coronagraphs is examined. Rather than identifying fast-moving optical coronal transients with outward-travelling shock waves that generate type II radio bursts, as has been suggested in some earlier papers, we suggest that, for the most part, such transients should probably be identified with piston-type phenomena well behind the shock. We then discuss a general model, consisting of three main velocity regimes, in which we relate type II radio bursts and coronal shocks to optically-observed ejecta.
TIME-DEPENDENT DENSITY FUNCTIONAL THEORY BEYOND THE ADIABATIC APPROXIMATION

I review recent advances in understanding the physical character of the exchange-correlation (xc) potential in time-dependent density functional theory. I show that in an electron gas of slowly varying density the dynamical part of the xc potential is an extremely nonlocal functional of the density. This difficulty can be circumvented by introducing an xc vector potential that is a function of the local current density. The form of this vector potential is entirely specified by symmetry. Its physical effects are analogous to those of the viscous force in the Navier-Stokes equation of classical hydrodynamics. Recent applications of the xc vector potential to the calculation of infrared absorption linewidths in quantum wells are described.
MODIFICATION OF THE BERKELEY HILAC.

Abstract A program is presently in progress for the modification of the Hilac to make possible the acceleration of ions of all masses to a maximum energy of 8.5 MeV/N. Present scheduling calls for the shut down of the existing Hilac in January 1971 and first beams from the modified system in August 1971. The improved accelerator will consist of a pressurized 2.5 MV Cockcroft-Walton injecting ions of minimum charge-to-mass ratio ϵ=0.045, at 0.112 MeV/N into an Alvarez linac. The linac will be separated at 1.2 MeV/N where particles will be stripped to a minimum ϵ=0.16. The second linac section will be partitioned into individual cavities of approximately equal velocity increments. Adjustment of rf phase and gradient in these cavities will provide variable energy from 2.6 to 8.5 MeV/N. All cavities will operate at 70.2 MHz and magnetic quadrupole focusing will be used throughout.
Teaching Quaternions is not Complex

Quaternions are used in many fields of science and computing, but teaching them remains challenging. Students can have a great deal of trouble understanding essentially what quaternions are and how they can represent rotation matrices. In particular, the similarity transform which actually achieves rotation, can often be baffling even after students have seen a full derivation. This paper outlines a constructive method for teaching quaternions, which allows students to build intuition about what quaternions are, and why simple multiplication is not adequate to represent a rotation. Through a set of examples, it demonstrates exactly how quaternions relate to rotation matrices, what goes wrong when qv is naively used to rotate vectors, and how the similarity transform fixes the problem.
A numerical study of the modulation of isotropic turbulence by suspended particles

Direct numerical simulations of a turbulent fluid laden with finite-sized particles are performed. The computations, on a 1283 grid along with a maximum of 262 144 particles, incorporated both direct particle interactions via hard-sphere collisions and particle feedback. The ‘reverse’ coupling is accomplished in a manner ensuring correct discrete energy conservation (Sundaram & Collins 1996). A novel two-field formalism (Sundaram & Collins 1994a) is employed to calculate two-point correlations and equivalent spectral densities. An important consideration in these simulations is the initial state of fluid and particles. That is, the initial conditions must be chosen so as to allow a meaningful comparison of the different runs. Using such a carefully initialized set of runs, particle inertia was observed to increase both the viscous and drag dissipations; however, simultaneously, it also caused particle velocities to correlate for longer distances. The combination of effects suggests a mechanism for turbulence enhancement or suppression that depends on the parameter values. Like previous investigators, ‘pivoting’ or crossover of the fluid energy spectra was observed. A possible new scaling for this phenomenon is suggested. Furthermore, investigations of the influence of particle mass and number densities on turbulence modulation are also carried out.
Modulus Prediction of a Cross-Ply Fiber Reinforced Fabric Composite With Voids

Voids or bubbles in polymer composites have a detrimental effect on the properties of the material. Such voids are found in PMR 15/graphite fiber (fabric type) composites. The matrix, PMR 15, is formed in-situ during the molding process and undergoes two major stages of reactions, viz., imidization and crosslinking. Volatiles are formed as by-products of these reactions and may remain trapped in the matrix to form voids or bubbles. Photomicrographs of composite cross sections suggested the classification of voids as two different phases in two different directions, each aligned with the fibers, resulting in a five phase model. The composites were tested in three-point bending tests to obtain the flexural modulus. By combining Weng's inclusion approach (1) and Ishikawa and Chou's crimp method (2), an analytical model has been developed to predict the elastic moduli of such a multiphase composite material. Thus, the voids have been treated as inclusions in an enclosing matrix, which in turn is reinforced by woven fibers in two directions. The stiffness behavior obtained analytically was within 10% of the experimental values.
On riesz means of eigenvalues

In this article we prove the equivalence of certain inequalities for Riesz means of eigenvalues of the Dirichlet Laplacian with a classical inequality of Kac. Connections are made via integral transforms including those of Laplace, Legendre, Weyl, and Mellin, and the Riemann–Liouville fractional transform. We also prove new universal eigenvalue inequalities and monotonicity principles for Dirichlet Laplacians as well as certain Schrodinger operators. At the heart of these inequalities are calculations of commutators of operators, sum rules, and monotonic properties of Riesz means. In the course of developing these inequalities we prove new bounds for the partition function and the spectral zeta function (cf. Corollaries 3.5–3.7) and conjecture about additional bounds.
ULTRADEEP NEAR-INFRARED OBSERVATIONS OF GOODS 850-5*, **

GOODS 850-5 is a hyperluminous radio-faint submillimeter source in the Great Observatories Origins Deep Survey-North. Although it is generally agreed that GOODS 850-5 is at a high redshift, z 4, its exact redshift is unknown. While its stellar spectral energy distribution (SED) suggests z ~ 6, its radio/far-IR (FIR) SED suggests a lower redshift of z ~ 4. To better constrain its stellar SED and redshift, we carried out nano-Jansky sensitivity ultradeep near-IR (NIR) observations between 1.2 and 2.1 μm with the Hubble Space Telescope and the 8 m Subaru Telescope. Even with such great depths we did not detect GOODS 850-5, and the results show that it is an extremely curious source. Between the Ks and 3.6 μm bands, its spectral slope is greater than 3 times that of an extremely red object, and the flux ratio between the two bands is greater than 8 times that of Lyman breaks. It is quite challenging to explain this unusually red color without a Lyman break (which would imply z > 17). It requires a large amount (M ~ 1011.5 M ☉) of reddened old stars at z ~ 6, coexisting with an even more extinguished violent ~2400-4400 M ☉ yr–1 starburst, which does not have any associated detectable rest-frame UV radiation. We discuss the discrepancy between the NIR and radio/FIR photometric redshifts. We conclude that GOODS 850-5 is at least at z > 4 and is more likely at z 6. We describe the unusual properties of GOODS 850-5, including its SED and formation history, and we discuss the implications of such massive z > 6 galaxies.
An unexpected synthesis of 3,5-diaryl-1,2,4-thiadiazoles from thiobenzamides and methyl bromocyanoacetate.

Abstract Aryl thioamides undergo very rapid condensation in the presence of methyl bromocyanoacetate to provide quantitative yields of 3,5-diaryl-1,2,4-thiadiazoles with an easy work-up and a high degree of product purity. The method can be scaled up with no loss in efficiency.
Precipitation and dissolution of calcium phosphonates for the enhancement of squeeze lifetimes

Injection of scale inhibitors into a formation is a commonly used technique to prevent scale formation during oil production. The success of a squeeze treatment often is determined by its effective lifetime in inhibiting scale in a reservoir system, and this lifetime is dictated by the retention/release mechanism of inhibitor in the reservoir. This paper focuses on a study of the precipitation/dissolution of calcium 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) in a porous medium to elucidate the important factors that affect the release of this precipitate. Experiments carried out in ceramic cores indicate that precipitation squeezes offer longer squeeze lifetimes and more HEDP retention than adsorption squeezes. Micromodel experiments show that the calcium-HEDP precipitate placed in porous media is made up of long, fibrous particles preferentially situated in pore throats. The elution from micromodels indicates that slow dissolution of apparently strong pore-throat plugs dictates the long tailing region. Finally, multiple-shut-in experiments performed in ceramic cores show that, while the amount of calcium-HEDP retention per shut-in does not increase with successive shut-ins, an enhanced returns effect is observed with respect to the squeeze lifetime.
Vibrational frequency shifts of fluid nitrogen fundamental and hot band transitions as a function of pressure and temperature

Coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman spectroscopy have been used to obtain vibrational spectra of shock-compressed and static high-pressure fluid nitrogen, respectively. Vibrational frequencies were obtained from the CARS data using a semiclassical model for these spectra. Spontaneous Raman vibrational frequencies were determined by fitting data using a Lorentz shape line. A functional form was found for the dependence of the vibrational frequency on pressure and temperature to 40 GPa and 5000 K, respectively. The result is compared to a recent theoretical model. 6 refs., 2 figs., 1 tab.
Adaptations of multimodal content in dialog systems targeting heterogeneous devices

Dialog systems that adapt to different user needs and preferences appropriately have been shown to achieve higher levels of user satisfaction [4]. However, it is also important that dialog systems be able to adapt to the user's computing environment, because people are able to access computer systems using different kinds of devices such as desktop computers, personal digital assistants, and cellular telephones. Each of these devices has a distinct set of physical capabilities, as well as a distinct set of functions for which it is typically used.Existing research on adaptation in both hypermedia and dialog systems has focused on how to customize content based on user models [2, 4] and interaction history. Some researchers have also investigated device-centered adaptations that range from low-level adaptations such as conversion of multimedia objects [6] (e.g., video to images, audio to text, image size reduction) to higher-level adaptations based on multimedia document models [1] and frameworks for combining output modalities [3, 5]. However, to my knowledge, no work has been done on integrating and coordinating both types of adaptation interdependently.The primary problem I would like to address in this thesis is how multimodal dialog systems can adapt their content and style of interaction, taking the user, the device, and the dependency between them into account. Two main aspects of adaptability that my thesis considers are: (1) adaptability in content presentation and communication and (2) adaptability in computational strategies used to achieve system's and user's goals.Beside general user modeling questions such as how to acquire information about the user and construct a user model, this thesis also considers other issues that deal with device modeling such as (1) how can the system employ user and device models to adapt the content and determine the right combination of modalities effectively? (2) how can the system determine the right combination of multimodal contents that best suits the device? (3) how can one model the characteristics and constraints of devices? and (4) is it possible to generalize device models based on modalities rather than on their typical categories or physical appearance.
Room Temperature Palladium-Catalyzed 2-Arylation of Indoles

This communication describes the rational development of a PdII-catalyzed method for the direct 2-arylation of indoles using [Ar−IIII−Ar]BF4. These reactions proceed under remarkably mild conditions (often at room temperature and in the presence of ambient air and moisture), and these features are believed to be the result of a PdII/IV mechanism operating in these systems. These transformations can be used to prepare functionally diverse 2-arylated indoles and pyrroles, and their potential utility has been expanded by the development of an in situ procedure for generating the iodine(III) arylating reagents.
High orbital eccentricities of extrasolar planets induced by the Kozai mechanism

One of the most remarkable properties of extrasolar planets revealed by the ongoing radial velocity surveys is their high orbital eccentricities, which are difficult to explain with our current theoretical paradigm for planet formation. Observations have shown that at least ~20% of these planets, including some with particularly high eccentricities, are orbiting a component of a wide binary star system. The presence of a distant binary companion can cause significant secular perturbations to the orbit of a planet. In particular, at high relative inclinations, a planet can undergo a large-amplitude eccentricity oscillation. This so-called Kozai mechanism is effective at a very long range, and its amplitude is purely dependent on the relative orbital inclination. In this paper, we address the following simple question: assuming that every host star with a detected giant planet also has a (possibly unseen, e.g., substellar) distant companion, with reasonable distributions of orbital parameters and masses, how well could secular perturbations reproduce the observed eccentricity distribution of planets? Our calculations show that the Kozai mechanism consistently produces an excess of planets with very high (e 0.6) and very low (e 0.1) eccentricities. Assuming an isotropic distribution of relative orbital inclination, we would expect that 23% of planets do not have sufficiently high inclination angles to experience the eccentricity oscillation. By a remarkable coincidence, only 23% of currently known extrasolar planets have eccentricities e < 0.1. However, this paucity of near-circular orbits in the observed sample cannot be explained solely by secular perturbations. This is because, even with high enough inclinations, the Kozai mechanism often fails to produce significant eccentricity perturbations when there are other competing sources of orbital perturbations on secular timescales, such as general relativity. Our results show that, with any reasonable set of mass and initial orbital parameters, the Kozai mechanism always leaves more than 50% of planets on near-circular orbits. On the other hand, the Kozai mechanism can produce many highly eccentric orbits. Indeed, the overproduction of high eccentricities observed in our models could be combined with plausible circularizing mechanisms (e.g., friction from residual gas) to create more intermediate eccentricities (e 0.1-0.6).
A study of the planetary nebulae Abell 30 and Abell 78

We have studied the central regions of the planetary nebulae A 30 and A 78 by UBVRI photometry, optical spectroscopy, and near-infrared photometry. The spectra contain high-excitation emission lines and strongly resemble those of Wolt-Rayet stars of the carbon sequence. We infer stellar temperatures > 50,000°K. The observed 3.5-ym flux of each nebula exceeds reasonable extrapolations of both the stellar flux and any possible free-free emission. The colour temperature of this excess between 2.28 and 3.5 /im is ∼ 1000°K. For each nebula, the aperture dependence of the excess emission suggests an extended (y10 arc-sec radius) region centred on the nucleus. Thermal radiation from a distribution of dust that is concentrated near the nuclei seems the most plausible explanation for the excess, but no theory of dust formation or heating seems totally adequate at present. (Paper will appear in the Monthly Notices of the Royal Astronomical Society.)
Initial Data for Numerical Relativity

Initial data are the starting point for any numerical simulation. In the case of numerical relativity, Einstein's equations constrain our choices of these initial data. We will examine several of the formalisms used for specifying Cauchy initial data in the 3 + 1 decomposition of Einstein's equations. We will then explore how these formalisms have been used in constructing initial data for spacetimes containing black holes and neutron stars. In the topics discussed, emphasis is placed on those issues that are important for obtaining astrophysically realistic initial data for compact binary coalescence.
Understanding Internet Video sharing site workload: A view from data center design

Internet Video sharing sites, led by YouTube , have been gaining popularity in a dazzling speed, which also brings massive workload to their service data centers. In this paper we analyze Yahoo! Video, the 2nd largest U.S. video sharing site, to understand the nature of such unprecedented massive workload as well as its impact on online video data center design. We crawled the Yahoo! Video web site for 46days. The measurement data allows us to understand the workload characteristics at different time scales (minutes, hours, days, weeks), and we discover interesting statistical properties on both static and temporal dimensions of the workload including file duration and popularity distributions, arrival rate dynamics and predictability, and workload stationarity and burstiness. Complemented with queueing-theoretic techniques, we further extend our understanding on the measurement data with a virtual design on the workload and capacity management components of a data center assuming the same workload as measured, which reveals key results regarding the impact of workload arrival distribution, Service Level Agreements (SLAs), and workload scheduling schemes on the design and operations of such large-scale video distribution systems.
Polytropes and Tropical Eigenspaces: Cones of Linearity

The map which takes a square matrix A to its polytrope is piecewise linear. We show that cones of linearity of this map form a polytopal fan partition of $\mathbb{R}^{n \times n}$ , whose face lattice is anti-isomorphic to the lattice of complete set of connected relations. This fan refines the non-fan partition of $\mathbb{R}^{n \times n}$ corresponding to cones of linearity of the eigenvector map. Our results answer open questions in a previous work with Sturmfels (Bull. Lond. Math. Soc. 54:27–36, 2013) and lead to a new combinatorial classification of polytropes and tropical eigenspaces.
Geometrically Mediated Breakup of Drops in Microfluidic Devices

Microfluidic technology offers capabilities for the precise handling of small fluid volumes dispersed as droplets. To fully exploit this potential requires simultaneous generation of multiple size droplets. We demonstrate two methods for passively breaking larger drops into precisely controlled daughter drops using pressure-driven flow in simple microfluidic configurations: (i) a T junction and (ii) flow past isolated obstacles. We quantify conditions for breakup at a T junction and illustrate sequential breakup at T junctions for making small drops at high dispersed phase volume fractions.
Prompting, feedback and error correction in the design of a scenario machine

Abstract A scenario machine limits the user to a single action path through system functions and procedures. Four scenario machines were designed to embody different approaches to prompting, feedback, and automatic error correction for a “learning-by-doing” training simulator for a commercial, menu-based word processor. Compared with users trained directly on the commercial system, scenario machine users demonstrated an overall advantage in the “getting started” stage of learning. Initial training on a “prompting + automatic correction” system was particularly efficient, encouraging a DWIM (or “do what I mean”) approach to training system design. Curiously, training on a “prompting + feedback” system led to relatively impaired performance on a set of transfer of learning tasks. It was suggested that too much training information support may obscure the task coherence of the action scenario itself relative to a design that provides less explicit direction.
Space constructible radiator on-orbit assembly

This paper discusses the most recent approaches for the on-orbit assembly of the space constructible radiator system (SCR) being developed for NASA's space station. Conceptual designs of suitable grappling hardware, radiator panel configurations, and insertion techniques are evaluated. Initial ground simulation results are presented using a six-degree-of-freedom (6-DOF) shuttle remote manipulator system (SRMS) simulator, both with and without force feedback. Radiator insertion in a close-tolerance rectangular opening has been achieved, without force feedback, using a special alignment target.
Minimal Surfaces in the Roto-Translation Group with Applications to a Neuro-Biological Image Completion Model

We investigate solutions to the minimal surface problem with Dirichlet boundary conditions in the roto-translation group equipped with a sub-Riemannian metric. By work of G. Citti and A. Sarti, such solutions are completions of occluded visual data when using a model of the first layer of the visual cortex. Using a characterization of smooth non-characteristic minimal surfaces as ruled surfaces, we give a method to compute a minimal spanning surface given fixed boundary data presuming such a surface exists. Moreover, we describe a number of obstructions to existence and uniqueness but also show that under suitable conditions, smooth minimal spanning surfaces with good properties exist. Not only does this provide an explicit realization of the disocclusion process for the neurobiological model, but it also has application to constructing disocclusion algorithms in digital image processing.
Deconstructing dimensional deconstruction

Abstract Dimensional deconstruction (DD) abstracts from higher dimensional models features of related 4-dimensional ones. DD was proposed in Refs. [1–3] as a scheme for constructing models of naturally light composite Higgs boson. These are models in which—without fine-tuning of parameters—the composite Higgs's mass M and vacuum expectation value v are much lighter than its binding energy scale Λ. We review the basic idea of DD. It is easy to arrange M ⪡ Λ. We show, however, that DD fails to give v ⪡ Λ in a model that is supposed to contain a naturally light composite Higgs [4].
Structure and anisotropy of the Mexico subduction zone based on Rayleigh‐wave analysis and implications for the geometry of the Trans‐Mexican Volcanic Belt

[1] We develop a three-dimensional model of shear wave velocity and anisotropy for the Mexico subduction zone using Rayleigh wave phase velocity dispersion measurements. This region is characterized by both steep and flat subduction and a volcanic arc that appears to be oblique to the trench. We give a new interpretation of the volcanic arc obliqueness and the location of the Tzitzio gap in volcanism based on the subduction morphology. We employ the two-station method to measure Rayleigh phase velocity dispersion curves between periods of 16 s to 171 s. The results are then inverted to obtain azimuthally anisotropic phase velocity maps and to model 3-D variations in upper mantle velocity and anisotropy. Our maps reveal lateral variations in phase velocity at all periods, consistent with the presence of flat and steep subduction. We also find that the data are consistent with two layers of anisotropy beneath Mexico: a crustal layer, with the fast directions parallel to the North American absolute plate motion, and a deeper layer that includes the mantle lithosphere and the asthenosphere, with the fast direction interpreted in terms of toroidal mantle flow around the slab edges. Our combined azimuthal anisotropy and velocity model enables us to analyze the transition from flat to steep subduction and to determine whether the transition involves a tear resulting in a gap between segments or is a continuous deformation caused by a lithospheric flexure. Our anisotropy results favor a tear, which is also consistent with the geometry of the volcanic belt.
Coordination chemistry of [P2Se6]4– in molten fluxes. Isolation of the structurally complex KMP2Se6(M = Sb, Bi)

The layered compounds, KMP2Se6(M = Sb, Bi), have been prepared by the reaction of Bi(Sb) with a molten alkali-metal polyselenophosphate flux.
The Living Will

To the Editor.— The excellent article by Eisendrath and Jonsen (1983; 249:2054) and the accompanying editorial (1983;249:2073) point out only some of the ethical issues involved in the living will. There are many others. Since it is extremely difficult to prognosticate accurately for critically ill patients and to determine whether the patient is irreversibly ill and whether death is imminent, the provisions of the living will may be activated prematurely. Alternatively, the existence of a living will may deprive the patient of the full efforts of the medical team who might not use the usual vigor and aggressive approach dictated by the patient's condition. If the patient changes his mind during the period when the living will is in effect yet fails to rescind the declaration formally, it may be activated without proper "informed consent." Heroic measures or "extraordinary treatment" is difficult to define precisely. What was heroic a few
Martian South Polar Layered Deposit stratigraphy and implications for accumulation history

[1] We examine the stratigraphy of the Martian South Polar Layered Deposits (SPLD) exposed on scarp walls throughout the deposit using THEMIS visible (17 m/pxl) images from the Mars Odyssey spacecraft. By correlating marker layers and packets of layers among multiple locations, we are able to identify three sequences of layers within the SPLD, each with a different areal extent. While certain layers are correlatable over hundreds of km, implying widespread deposition of polar material, the absence of several identified layer sequences in some regions, notably the Promethei Lingula region, as well as the presence of several unconformities, indicates that deposition and sublimation or erosion of these deposits has not been uniform around the SPLD. This is further supported by the fact that individual layers display variations in thickness greater than a factor of 4 over hundreds of kilometers. Using these observations we propose an internal structure for the SPLD, with individual layers roughly following a dome-like shape toward the center of the deposit, and becoming more planar toward the margins. We infer that the SPLD underwent at least three major periods of layer accumulation; each period is distinguished by a change in areal extent of net accumulation. The changes in areal extent of the layer sequences may be due to changes in Martian climate causing episodes of significant erosion of the SPLD between the deposition of each sequence or causing wide variations in accumulation zones of the SPLD over the history of these deposits.
Falsification of LTL safety properties in hybrid systems

This paper develops a novel approach for the falsification of safety properties given by a syntactically safe linear temporal logic (LTL) formula $${\phi}$$ for hybrid systems with nonlinear dynamics and input controls. When the hybrid system is unsafe, the approach computes a trajectory that indicates violation of $${\phi}$$ . The approach is based on an effective combination of model checking and motion planning. Model checking searches on-the-fly the automaton of $${\neg\phi}$$ and an abstraction of the hybrid system for a sequence σ of propositional assignments that violates $${\phi}$$ . Motion planning incrementally extends trajectories that satisfy more and more of the propositional assignments in σ. Model checking and motion planning regularly exchange information to find increasingly useful sequences σ for extending the current trajectories. Experiments that test LTL safety properties on a robot navigation benchmark modeled as a hybrid system with nonlinear dynamics and input controls demonstrate the computational efficiency of the approach. Experiments also indicate significant speedup when using minimized DFA instead of non-minimized NFA for representing $${\neg\phi}$$ .
The Lennox-Gastaut syndrome: a severe type of childhood epilepsy.

The Lennox-Gastaut syndrome is characterized by a) severe convulsive disorder with various types of seizures, b) mental retardation, c) slow spike-wave complexes in the EEG, d) heterogeneous etiologies and variable pathological substrata, e) a very poor response to the usual anticonvulsive medication (with the possible exception of Diazepam (Valium)). The onset falls into infancy and childhood, rarely into adolescence. The occurrence of atonic-akinetic seizures and purely tonic attacks are helpful in establishing the diagnosis which should be corroborated by the EEG.
Regular decomposition of ordinarity in generic exponential sums

Abstract In [16] (1993) and [18] (2004) Wan establishes a decomposition theory for the generic Newton polygon associated to a family of L-functions of n-dimensional exponential sums over finite fields. In this work we generalize the star, parallel hyperplane and collapsing decomposition, demonstrating that each is a generalization of a complete regular decomposition.
Formal [2 + 2 + 2] cycloaddition strategy based on an intramolecular propargylic ene reaction/Diels-Alder cycloaddition cascade.

A formal, metal-free, [2 + 2 + 2] cycloaddition strategy is described based on a cascade of two pericyclic processes. The first step involves an intramolecular propargylic ene reaction of a 1,6-diyne to generate a vinylallene, which then reacts in an inter- or intramolecular Diels−Alder reaction with an alkenyl or alkynyl dienophile. Reactions involving unsymmetrical alkenyl and alkynyl dienophiles proceed with good to excellent regioselectivity, and the diastereoselectivity in the Diels−Alder step is also high, with endo cycloadducts produced as the exclusive products of the reaction. In the case of alkynyl dienophiles, [4 + 2] cycloaddition initially generates an isotoluene-type intermediate that isomerizes to the isolated aromatic product upon exposure to a catalytic amount of DBU at room temperature. The mechanism of several earlier fully intramolecular related transformations have been shown to involve an analogous process rather than the diradical-mediated pathways proposed previously.
An environmentally benign solvent-free Tishchenko reaction

Herein, we describe the solvent-free ball milling Tishchenko reaction. Using high speed ball milling and a sodium hydride catalyst, the Tishchenko reaction was performed for aryl aldehydes in high yields in 0.5 hours. The reaction is not affected by the type of ball bearing used and can be successful when conducted in a liquid nitrogen environment.
Using Scanner Data to Estimate Country Price Parities: A Hedonic Regression Approach

This paper uses scanner data from the bar-code readers of retailers to provide estimates of inter-country price parities at the level of the basic heading. The use of such data is appealing given its extensive coverage of transactions, information on weights, prices and characteristics of items at a highly detailed level. The study uses dummy variable hedonic and exact/superlative hedonic index number formulations applied to an inter-country context for both bilateral and multilateral comparisons. Unlike conventional methods, such methods are not confined to matched samples comparisons and thus make use of the entire sample. Their application extends to price survey data using checklists on characteristics. The application is to scanner data on about 1 million transactions for television sets over two months in three countries. It is, to the authors’ knowledge, the first such use of scanner data and application of the above hedonic frameworks in this context.
The effects of an ion-thruster exhaust plume on S-band carrier transmission

The magnitude of the effects of an ion thruster plume on S-band signals is measured. Modeling techniques are developed to predict the effects. Results show that the RF signal transmitted through an ion thruster plume is reduced in amplitude and shifted in phase. An increase in noise is also experienced.