cssi/SciSciGPT-SciSciNet huggingface dataset:
LONG-TERM EVOLUTION OF PROTOSTELLAR AND PROTOPLANETARY DISKS. II. LAYERED ACCRETION WITH INFALL

We use one-dimensional two-zone time-dependent accretion disk models to study the long-term evolution of protostellar disks subject to mass addition from the collapse of a rotating cloud core. Our model consists of a constant surface density magnetically coupled active layer, with transport and dissipation in inactive regions only via gravitational instability. We start our simulations after a central protostar has formed, containing ~10% of the mass of the protostellar cloud. Subsequent evolution depends on the angular momentum of the accreting envelope. We find that disk accretion matches the infall rate early in the disk evolution because much of the inner disk is hot enough to couple to the magnetic field. Later infall reaches the disk beyond ~10 AU, and the disk undergoes outbursts of accretion in FU Ori-like events as described by Zhu et al. If the initial cloud core is moderately rotating, most of the central star's mass is built up by these outburst events. Our results suggest that the protostellar "luminosity problem" is eased by accretion during these FU Ori-like outbursts. After infall stops, the disk enters the T Tauri phase. An outer, viscously evolving disk has a structure that is in reasonable agreement with recent submillimeter studies and its surface density evolves from Σ ∝ R –1 to R –1.5. An inner, massive belt of material—the "dead zone"—would not have been observed yet but should be seen in future high angular resolution observations by EVLA and ALMA. This high surface density belt is a generic consequence of low angular momentum transport efficiency at radii where the disk is magnetically decoupled, and would strongly affect planet formation and migration.
Construct validity of the computerized version of the category test

The purpose of the current study was to investigate the construct validity of the computer version of the Category Test (CT) in relation to the standard version. As part of a comprehensive neuropsychological assessment, outpatient rehabilitation clients completed either the standard CT (n = 49) or the computerized version (n = 56). Two principal component factor analyses were performed and the factor structures compared to a solution reported previously in the literature. Inspection of the factor loadings revealed a similarity between the computerized CT and standard CT groups as well as with the previously reported analysis. The results of this study suggest that regardless of the mode of administration the CT loads on a “spatial abilities” factor and provides support for the construct validity of the computerized CT as part of a comprehensive neuropsychological testing battery. © 1997 John Wiley & Sons, Inc. J Clin Psychol 53: 723–726, 1997.
A Reduced-Order Model of Mistuning Using a Subset of Nominal System Modes

Reduced-order models have been reported in the literature that can be used to predict the harmonic response of mistuned bladed disks. It has been shown that in many cases they exhibit structural fidelity comparable to a finite element analysis of the full bladed disk system while offering a significant improvement in computational efficiency. In these models the blades and disk are treated as distinct substructures. This paper presents a new, simpler approach for developing reduced-order models in which the modes of the mistuned system are represented in terms of a subset of nominal system modes. It has the following attributes: the input requirements are relatively easy to generate; it accurately predicts mistuning effects in regions where frequency veering occurs; as the number of degrees-of-freedom increases it converges to the exact solution; it accurately predicts stresses as well as displacements; and it accurately models the deformation and stresses at the blades' bases.
A concise route to a key intermediate in the total syntheses of (+)-tirandamycic acid and (-)-tirandamycin a †

Abstract An efficacious, asymmetric synthesis of the 2,9-dioxabicyclo[3,3,1]nonane 4 has been completed in nine chemical steps from 4,5-dimethylfuraldehyde (8). Since enantiomerically pure 4 has been previously converted in five steps by Ireland into (+)-tirandamycic acid (3) and more recently by Schlessinger into (-)-tirandamycin A (1), this achievement constitutes in a strictly formal sense the total syntheses of these substances. The key step in the synthesis of 4 features the transformation of the enantiomerically pure furfuryl diol 25 into 29 by initial selective oxidation of (the furan ring and subsequent acid-catalyzed bicycloketalization.
A numerical study of the hierarchical Ising model: High-temperature versus epsilon expansion

We study numerically the magnetic susceptibility of the hierarchical model with Ising spins (σ=±1) above the critical temperature and for two values of the epsilon parameter. The integrations are performed exactly using recursive methods which exploit the symmetries of the model. Lattices with up to 218 sites have been used. Surprisingly, the numerical data can be fitted very well with a simple power law of the form (1-β/β0)g for thewhole temperature range considered. This approximate law implies a simple approximate formula for the coefficients of the high-temperature expansion, and, more importantly, approximate relations among the coefficients themselves. We found that some of these approximate relations hold with errors less then 2%. On the other hand,g differs significantly from the critical exponent γ calculated with the epsilon expansion, even when the fit is restricted to intervals closer toβc. We discuss this discrepancy in the context the renormalization group analysis of the hierarchical model.
Orbit Determination Accuracies Using Satellite-to-Satellite Tracking

The results are reported of the ATS-6/GEOS-3 and the ATS-6 NIMBUS-6 satellite-to-satellite orbit determination experiments. NASA intends to use the tracking data relay satellite system for operational orbit determination of NASA satellites. Hence, in the near future, satellite-to-satellite tracking data will be routinely processed to obtain orbits. The satellite-to-satellite tracking system used in the ATS-6/NIMBUS-6 and ATS-6/GEOS-3 experiments performed with a resolution of 1 to 2 m in range and less than 1 mm/s in range rate for a 10-s averaging. A Bayesian least squares estimation technique utilizing independent ranging to the synchronous relay satellite was determined to be the most effective procedure for estimating orbits from satellite-to-satellite tracking data. The use of this technique yields estimates of user satellite orbits which are comparable in accuracy to what is usually obtained from ground based systems.
Synergetic fluid mixing from viscous fingering and alternating injection.

We study mixing of two fluids of different viscosity in a microfluidic channel or porous medium. We show that the synergetic action of alternating injection and viscous fingering leads to a dramatic increase in mixing efficiency at high P\'eclet numbers. Based on observations from high-resolution simulations, we develop a theoretical model of mixing efficiency that combines a hyperbolic mixing model of the channelized region ahead and a mixing-dissipation model of the pseudosteady region behind. Our macroscopic model quantitatively reproduces the evolution of the average degree of mixing along the flow direction and can be used as a design tool to optimize mixing from viscous fingering in a microfluidic channel.
Boolean and Cartesian abstraction for model checking C programs

We show how to attack the problem of model checking a C program with recursive procedures using an abstraction that we formally define as the composition of the Boolean and the Cartesian abstractions. It is implemented through a source-to-source transformation into a `Boolean' C program; we give an algorithm to compute the transformation with a cost that is exponential in its theoretical worst-case complexity but feasible in practice.
A REVIEW OF THREE-FAMILY GRAND UNIFIED STRING MODELS

We review the construction and classification of three-family grand unified models within the framework of asymmetric orbifolds in perturbative heterotic superstring. We give a detailed survey of all such models which is organized to aid analysis of their phenomenological properties. We compute tree level superpotentials for these models. These superpotentials are used to analyze the issues of proton stability (doublet–triplet splitting and R-parity-violating terms) and Yukawa mass matrices. To have agreement with phenomenological data all these models seem to require a certain degree of fine-tuning. We also analyze the possible patterns of supersymmetry breaking in these models. We find that the supersymmetry breaking scale comes out either too high to explain the electroweak hierarchy problem, or below the electroweak scale unless some degree of fine-tuning is involved. Thus, none of the models at hand seem to be phenomenologically flawless.
The geodesic flow of a nonpositively curved graph manifold

We consider discrete cocompact isometric actions $ G \curvearrowright^{\rho} X $ where X is a locally compact Hadamard space (following [B] we will refer to CAT(0) spaces — complete, simply connected length spaces with nonpositive curvature in the sense of Alexandrov — as Hadamard spaces) and G belongs to a class of groups (“admissible groups”) which includes fundamental groups of 3-dimensional graph manifolds. We identify invariants (“geometric data”) of the action $ \rho $ which determine, and are determined by, the equivariant homeomorphism type of the action $G \curvearrowright^{\partial_\infty \rho}\,\partial_\infty X X $ of G on the ideal boundary of X. Moreover, if $ G \curvearrowright^{\rho}i X_i $ are two actions with the same geometric data and $ \Phi : X_1 \to X_2 $ is a G-equivariant quasi-isometry, then for every geodesic ray $ \gamma_1 : [0, \infty) \to X_1 $ there is a geodesic ray $ \gamma_2 : [0, \infty) \to X_2 $ (unique up to equivalence) so that $ {\rm lim}_{t \to \infty} {1 \over t}\,d_{X_2}(\Phi \circ \gamma_1(t), \gamma_2([0, \infty))) = 0 $ . This work was inspired by (and answers) a question of Gromov in [Gr3, p. 136].
From Angular Manifolds to the Integer Lattice: Guaranteed Orientation Estimation With Application to Pose Graph Optimization

Pose graph optimization from relative measurements is challenging because of the angular component of the poses: the variables live on a manifold product with nontrivial topology and the likelihood function is nonconvex and has many local minima. Because of these issues, iterative solvers are not robust to large amounts of noise. This paper describes a global estimation method, called multi-hypothesis orientation-from-lattice estimation in 2-D (MOIE2D), for the estimation of the nodes' orientation in a pose graph. We demonstrate that the original nonlinear optimization problem on the manifold product is equivalent to an unconstrained quadratic optimization problem on the integer lattice. Exploiting this insight, we show that, in general, the maximum likelihood estimate alone cannot be considered a reliable estimator. Therefore, MOIE2D returns a set of point estimates, for which we can derive precise probabilistic guarantees. Experiments show that the method is able to tolerate extreme amounts of noise, far above all noise levels of sensors used in applications. Using MOIE2D's output to bootstrap the initial guess of iterative pose graph optimization methods improves their robustness and makes them avoid local minima even for high levels of noise.
A Bivariate Multicanonical Monte Carlo of the 3D ±J Spin Glass

A bivariate multicanonical Monte Carlo simulation of the three-dimensional ±J Ising spin glass is described. The autocorrelation time is approximately proportional to the system size, which is a great improvement over previous spin-glass simulations. The Binder plot indicates the critical temperature T c ⋍ 1.3. The orderp-arameter distribution function P(q) exhibits a feature of the droplet picture of the low-temperature phase.
Corporate Sponsorships of Philanthropic Activities: When Do They Impact Perception of Sponsor Brand?

We examined the benefits to a corporate sponsor of two types of philanthropic activities — cause promotions and advocacy advertising. Results from 4 laboratory studies indicate that perceptions of corporate social responsibility (CSR) are affected by consumers’ elaboration levels. Consumer perceptions of CSR are more favorable for cause promotions, which do not receive much elaboration, than they are for advocacy advertising, which prompts more elaboration. In addition, perceived congruence between the sponsor and the social issue is shown to moderate these effects: Higher congruence between the sponsor and social issue increases favorable ratings of CSR for cause promotions but only if elaboration on the sponsorship activity is facilitated. On the other hand, lower congruence increases favorable ratings of CSR for advocacy advertising as long as elaboration on the sponsorship is not constrained. We also found that higher congruence enhances CSR ratings if participants are primed to focus their attention on the sponsor brand, whereas lower congruence enhances CSR if participants are primed to focus their attention on the social issue.
Simulation of multivariate normal rectangle probabilities and their derivatives theoretical and computational results

Abstract An extensive literature in econometrics and in numerical analysis has considered the problem of evaluating the multiple integral P(B; μ, Ω) = ∝ a b n(v − μ, Ω)dv ≡ E v 1(V ϵ B) , where V is a m-dimensional normal vector with mean μ, covariance matrix Ω, and density n(v − μ, Ω) , and 1(V ϵ B) is an indicator for the event B = (V¦a . A leading case of such an integral is the negative orthant probability, where B = (V ¦V . The problem is computationally difficult except in very special cases. The multinomial probit (MNP) model used in econometrics and biometrics has cell probabilities that are negative orthant probabilities, with μ and Ω depending on unknown parameters (and, in general, on covariates). Estimation of this model requires, for each trial parameter vector and each observation in a sample, evaluation of P(B; μ, Ω) and of its derivatives with respect to μ and Ω. This paper surveys Monte Carlo techniques that have been developed for approximations of P(B; μ, Ω) and its linear and logarithmic derivatives, that limit computation while possessing properties that facilitate their use in iterative calculations for statistical inference: the Crude Frequency Simulator (CFS), Normal Importance Sampling (NIS), a Kernel-Smoothed Frequency Simulator (KFS), Stern's Decomposition Simulator (SDS), the Geweke-Hajivassiliou-Keane Simulator (GHK), a Parabolic Cylinder Function Simulator (PCF), Deak's Chi-squared Simulator (DCS), an Acceptance/Rejection Simulator (ARS), the Gibbs Sampler Simulator (GSS), a Sequentially Unbiased Simulator (SUS), and an Approximately Unbiased Simulator (AUS). We also discuss Gauss and FORTRAN implementations of these algorithms and present our computational experience with them. We find that GHK is overall the most reliable method.
Vortex-interface interactions and generation of glitches in pulsars

ABSTRA C T We show that the crust‐core interface in neutron stars acts as a potential barrier to the peripheral neutron vortices approaching the interface in the model in which these are coupled to the proton vortex clusters. This elementary barrier arises because of the interaction of vortex magnetic flux with the Meissner currents set up by the crustal magnetic field at the interface. The dominant part of the force is derived from the cluster‐interface interaction. As a result of the stopping of the continuous neutron vortex current through the interface, angular momentum is stored in the superfluid layers in the vicinity of the crust‐ core interface during the interglitch period. Discontinuous annihilation of proton vortices at the boundary restores the neutron vortex current and spins up the observable crust on short time-scales, leading to a glitch in the spin characteristics of a pulsar.
The synthesis and crystal structure of 2,6,9-trimethyl-4,8-dinitro-2,6,9-triazabicyclo[3.3.1]nona-3,7-diene

The first preparation of title compound 1 is accomplished. Its heterocyclic structure was characterized spectroscopically and by X-ray structure analysis.
Amplitude and time measurement ASIC with analog derandomization

Abstract A versatile 32-channel ASIC has been developed for accurate processing of high-rate pulse signals from highly segmented detectors. In contrast to conventional approaches, this circuit affords a dramatic reduction in data volume through the use of analog techniques (precision peak detectors and time-to-amplitude converters) together with fast arbitration and sequencing logic to concentrate the data before digitization. In operation the circuit functions like a data-driven analog first-in, first-out (FIFO) memory between the preamplifiers and the ADC. Peak amplitudes of pulses arriving at any one of the 32 inputs are sampled, stored, and queued for readout and digitization through a single output port. Hit timing, pulse risetime, and channel address are also available at the output. Prototype chips have been fabricated in 0.35 μm CMOS and tested. Amplitude accuracy of the peak detect and hold circuit is 0.2% (absolute) and 0.04% (nonlinearity) for signals within 0.3 V of either supply rail. Time walk is below 5 ns, droop rate is 250 mV/s, and power consumption is less than 2 mW/channel at pulse rates up to 500 kHz per channel.
Turbulence and turbulent mixing in natural fluids

Turbulence and turbulent mixing in natural fluids begin with big bang turbulence powered by spinning combustible combinations of Planck particles and Planck antiparticles. Particle prograde accretions on a spinning pair release 42% of the particle rest mass energy to produce more fuel for turbulent combustion. Negative viscous stresses and negative turbulence stresses work against gravity, extracting mass-energy and space-time from the vacuum. Turbulence mixes cooling temperatures until strong-force viscous stresses freeze out turbulent mixing patterns as the first fossil turbulence. Cosmic microwave background temperature anisotropies show big bang turbulence fossils along with fossils of weak plasma turbulence triggered as plasma photon-viscous forces permitting gravitational fragmentation on supercluster to galaxy mass scales. Turbulent morphologies and viscous-turbulent lengths appear as linear gas-protogalaxy-clusters in the Hubble ultra-deep field at z 7. Protogalaxies fragment into Jeans mass clumps of primordial-gas planets at decoupling: the dark matter of galaxies. Shortly after the plasma-to-gas transition, planet mergers produce stars that explode on overfeeding to fertilize and distribute the first life.
Carbon isotopic composition of cypress trees from South Florida and changing hydrologic conditions

Abstract δ13C values were determined from cypress tree rings from two different study areas in South Florida. One site is located in the Southeastern Everglades Marsh, where pond cypress (Taxodium ascendens) was sampled from tree islands (annual tree rings from 1970 to 2000). Bald cypress (Taxodium distichum) trees were sampled at the other site, located along the Loxahatchee River in a coastal wetland (decadal tree rings from 1830 to 1990). The isotopic time series from both sites display different, location-specific information. The pond cypress isotopic time series has a positive correlation with the total amount of annual precipitation, while the bald cypress data from the Loxahatchee River study area had two different records dependent on the level of saltwater stress. In general, for terrestrial trees growing in a temperate environment, water stress causes an increase in water-use efficiency (WUE) resulting in a relative 13C enrichment. Yet, trees growing in wetland settings in some cases do not respond in the same manner. We propose a conceptual model based on changes in carbon assimilation and isotopic fractionation as controlled by differences in stomatal resistance (water stress) and mesophyll resistance (biochemical and nutrient related) to explain the isotopic records from both sites. With further work and a longer time series, our approach may be tested, and used to reconstruct change in hydroperiods further back in time, and potentially provide a baseline for wetland restoration.
High energy gamma rays

Abstract This article reviews the present status of high energy γ-ray astronomy at energies above 30 MeV. Observations in the past decade using both space- and ground-based experiments have been primarily responsible for giving a tremendous boost to our knowledge of the high energy Universe. High energy γ-rays have been detected from a wide range of Galactic and extragalactic astrophysical sources, such as γ-ray bursters, pulsars, and active galaxies. These observations have established high energy γ-ray astronomy as a vital and exciting field, that has a bright future. This review summarizes the experimental techniques, observations and results obtained with recent experiments, and concludes with a short description of future prospects.
Bar constructions and Quillen homology of modules over operads

We show that topological Quillen homology of algebras and modules over operads in symmetric spectra can be calculated by realizations of simplicial bar constructions. Working with several model category structures, we give a homotopical proof after showing that certain homotopy colimits in algebras and modules over operads can be easily understood. A key result here, which lies at the heart of this paper, is showing that the forgetful functor commutes with certain homotopy colimits. We also prove analogous results for algebras and modules over operads in unbounded chain complexes.
Taming distributed system complexity through formal patterns

Many distributed systems are real-time, safety-critical systems with strong qualitative and quantitative formal requirements. They often need to be reflective and adaptive, and may be probabilistic in their algorithms and/or their operating environments. All this makes these systems quite complex and therefore hard to design, build and verify. To tame such system complexity, this paper proposes formal patterns, that is, formally specified solutions to frequently occurring distributed system problems that are generic, executable, and come with strong formal guarantees. The semantics of such patterns as theory transformations in rewriting logic is explained; and a representative collection of useful patterns is presented to ground all the key concepts and show their effectiveness.
Inductive methods for proving properties of programs

There are two main purposes in this paper: first, clarification and extension of known results about computation of recursive programs, with emphasis on the difference between the theoretical and practical approaches; second, presentation and examination of various known methods for proving properties of recursive programs. Discussed in detail are two powerful inductive methods, computational induction and structural induction, including examples of their applications.
Relativistic jets and long-duration gamma-ray bursts from the birth of magnetars

We present time-dependent axisymmetric magnetohydrodynamic simulations of the interaction of a relativistic magnetized wind produced by a proto-magnetar with a surrounding stellar envelope, in the first � 10 seconds after core collapse. We inject a super-magnetosonic wind with u E = 10 51 ergs s 1 into a cavity created by an outgoing supernova shock. A strong toroidal magnetic field builds up in the bubble of plasma and magnetic field that is at first inertially confined by the progenitor star. This drives a jet out along the polar axis of the star, even though the star and the magnetar wind are each spherically symmetric. The jet has the properties needed to produce a longduration gamma-ray burst (GRB). At � 5 s after core bounce, the jet has escaped the host star and the Lorentz factor of the material in the jet at large radii � 10 11 cm is similar to that in the magnetar wind near the source. Most of the spindown power of the central magnetar escapes via the relativistic jet. There are fluctuations in the Lorentz factor and energy flux in the jet on � 0.01 0.1 second timescale. These may contribute to variability in GRB emission (e.g., via internal shocks).
The projectile inside the loop

The loop-the-loop demonstration can be easily adapted to study the kinematics of projectile motion, when the moving body falls inside the apparatus. Video capturing software can be used to reveal peculiar geometrical effects of this simple but educational experiment.
New electrolytic etchant for dislocation etch pits in Ni3Al single crystals

Abstract A new etchant for developing etch pits at screw dislocation sites in Ni3Al single crystals was tested. Using this etchant, both fresh and aged dislocations can be revealed on {001} surfaces. The usefulness of the etching technique was demonstrated further on crystals which had been plastically deformed either under an impact load or under a hardness indentation. It was shown that there is a direct correspondence between the etch-pit pattern and slip lines around the indentation. Observations were also made on the dislocation etch pits in Ni3Al single crystals alloyed with boron and hafnium.
Simple type and the boundary of moduli space

Abstract We measure, in two distinct ways, the extent to which the boundary region of moduli space contributes to the “simple type” condition of Donaldson theory. Using the natural geometric representative of μ (pt) defined in [L. Sadun, Commun. Math. Phys. 178 (1996) 107–113], the boundary region of moduli space contributes 6 64 of the homology required for simple type, regardless of the topology or geometry of the underlying 4-manifold. The simple type condition thus reduces to the interior of the ( k +1)th ASD moduli space, intersected with two representatives of (4 times) the point class, being homologous to 58 copies of the k th moduli space. This is peculiar, since the only known embeddings of the k th moduli space into the ( k +1)th involve Taubes gluing, and the images of such embeddings lie entirely in the boundary region. When using the natural de Rham representatives of μ (pt) considered by Witten [Commun. Math. Phys. 117 (1988) 353], the boundary region contributes 1 8 of what is needed for simple type, again regardless of the topology or geometry of the underlying 4-manifold. The difference between this and the geometric representative answer is not contradictory, as the contribution of a fixed region to the Donaldson invariants is geometric, not topological.
Counting immersed surfaces in hyperbolic 3–manifolds

We count the number of conjugacy classes of maximal, genus g, surface subroups in hyperbolic 3-manifold groups. For any closed hy- perbolic 3-manifold, we show that there is an upper bound on this number which grows factorially with g. We also give a class of closed hyperbolic 3-manifolds for which there is a lower bound of the same type. AMS Classification 57M50; 57N16, 57M27
Experimental and computational studies of jamming

Jamming is a common feature of out-of-equilibrium systems showing slow relaxation dynamics. Here we review our efforts in understanding jamming in granular materials using experiments and computer simulations. We first obtain an estimation of an effective temperature for a slowly sheared granular material very close to jamming. The measurement of the effective temperature is realized in the laboratory by slowly shearing a closely packed ensemble of spherical beads confined by an external pressure in a Couette geometry. All the probe particles, independent of their characteristic features, equilibrate at the same temperature, given by the packing density of the system. This suggests that the effective temperature is a state variable for the nearly jammed system. Then we investigate numerically whether the effective temperature can be obtained from a flat average over the jammed configuration at a given energy in the granular packing, as postulated by the thermodynamic approach to grains.
Is there a ‘marriage premium’ for gay men?

It is well-known that married men earn more than comparable single men, with typical estimates of the male marriage premium in the range of 10–20%. Some research also finds that cohabiting men earn more than men not living with a female partner. This study uses data from the General Social Survey and the National Health and Social Life Survey to examine whether a similar premium accrues to gay men who live with a male partner and whether cohabiting gay men have different observable characteristics than non-cohabiting gay men. Controlling for observable characteristics, cohabiting gay men do not earn significantly more than other gay men or more than unmarried heterosexual men. Cohabiting heterosexual men also do not earn more than non-cohabiting heterosexual men.
Inequality of Wealth in the Ottoman Empire: War, Weather, and Long-Term Trends in Eighteenth-Century Kastamonu

This article offers a quantitative analysis of wealth inequality in the Ottoman Empire, employing data from probate inventories (terekes) of eighteenth-century Kastamonu, a town located in northern Anatolia. Extracting information on wealth levels and personal characteristics of individuals, we estimate aggregate measures of wealth inequality, namely the Gini coefficient, the coefficient of variation, and the wealth shares of the wealthiest 10 and 25 percent of estates. We use regression analysis to identify the time trend of wealth inequality and determine how warfare, significant weather events, macroeconomic variables, and shifts in population characteristics affected it.
Real Time Blood Testing Using Quantitative Phase Imaging

We demonstrate a real-time blood testing system that can provide remote diagnosis with minimal human intervention in economically challenged areas. Our instrument combines novel advances in label-free optical imaging with parallel computing. Specifically, we use quantitative phase imaging for extracting red blood cell morphology with nanoscale sensitivity and NVIDIA’s CUDA programming language to perform real time cellular-level analysis. While the blood smear is translated through focus, our system is able to segment and analyze all the cells in the one megapixel field of view, at a rate of 40 frames/s. The variety of diagnostic parameters measured from each cell (e.g., surface area, sphericity, and minimum cylindrical diameter) are currently not available with current state of the art clinical instruments. In addition, we show that our instrument correctly recovers the red blood cell volume distribution, as evidenced by the excellent agreement with the cell counter results obtained on normal patients and those with microcytic and macrocytic anemia. The final data outputted by our instrument represent arrays of numbers associated with these morphological parameters and not images. Thus, the memory necessary to store these data is of the order of kilobytes, which allows for their remote transmission via, for example, the cellular network. We envision that such a system will dramatically increase access for blood testing and furthermore, may pave the way to digital hematology.
Mars: Near-infrared comparative spectroscopy during the 1986 opposition☆☆☆

Near-IR, 0.7-2.5 micron spectra were obtained for several Martian locations during the 1986 opposition, using a continuously variable filter spectrometer; approximately 60 distinct spots were observed at 0.5-1.5 arcsec (200-460 km) resolution which are distinguishable into eight distinct geologic types: (1) volcanic regions, (2) ridged plains, (3) ridged volcanic plains, (4) scoured plains, (5) impact basins, (6) channels and canyons, (7) densely-cratered regions, and (8) layered terrain and ice. Spectral features observed in the spot-to-spot ratios for spectra from different geologic regions are used as indicators of mineralogic differences. Little difference is found among spectra from areas that appear to have very different morphologies in Viking Orbiter images.
Evaluation of chest computed tomography in the staging of patients with potentially resectable liver metastases from colorectal carcinoma

BACKGROUND Chest computed tomography (CT) often is used to rule out lung metastases in patients with potentially resectable liver metastases from colorectal carcinoma. In the current study the authors evaluated whether CT of the chest was necessary in patients with a negative chest radiograph. METHODS The authors performed a retrospective analysis of 202 patients with negative initial chest X-rays who were undergoing evaluation for potentially resectable liver metastases from colorectal carcinoma. Patients with highly suspicious pulmonary lesions on the initial chest CT scan underwent a thoracoscopy and biopsy. All patients were monitored for the development of pulmonary metastases. RESULTS Sixty patients (30%) had a positive initial chest CT scan. Two patients were found to have metastases by comparison with prior CT scans. Seventeen patients had highly suspicious lesions that were biopsied, but only 2 were found to have pulmonary metastases; the other lesions were benign. An additional 13 of these 60 patients developed lung metastases during follow-up, 6 of whom were diagnosed in retrospect. Of the 142 patients with a negative initial CT scan, 33 (23%) developed pulmonary metastases. The rate of pulmonary metastases in both groups was not significantly different, regardless of whether the CT scans were positive or negative. CONCLUSIONS During routine preoperative workup for liver resection, the majority of lesions appearing on chest CT scans of patients with negative chest radiographs were not malignant. The positive yield of CT-guided workup was only 10 of 202 patients (5%). Based on this review the authors question the use of chest CT scans in this setting. Cancer 1999;86:229–35. © 1999 American Cancer Society.
A note on the quantum-tail effect on fusion reaction rate

A study is made of the power-law tail effect in the quantum particle distribution over momentum on the nuclear fusion reactions. Our results do not support the idea of averaging the fusion reaction cross-section over the momentum distribution, postulated and used in many publications.
Dynamics of internal stresses and scaling of strain recovery in an aging colloidal gel.

We monitor the relaxation of internal stresses in a fractal colloidal gel on cessation of flow and find a weak power-law decay, ${\ensuremath{\sigma}}_{i}\ensuremath{\sim}{t}^{\ensuremath{-}\ensuremath{\alpha}}$ over five decades of time where $\ensuremath{\alpha}\ensuremath{\approx}0.07$. The system exhibits physical aging of the elastic modulus, ${G}^{\ensuremath{'}}\ensuremath{\sim}{t}^{\ensuremath{\beta}}$, with $\ensuremath{\beta}\ensuremath{\approx}\ensuremath{\alpha}$. Imposition of zero stress after waiting time ${t}_{w}$ results in strain recovery as the system relaxes without constraint. Remarkably, recoveries at different ${t}_{w}$ can be shifted to construct a master curve where data are scaled vertically by $1/{\ensuremath{\sigma}}_{i}({t}_{w})$ and plotted horizontally as $(t\ensuremath{-}{t}_{w})/{t}_{w}^{\ensuremath{\mu}}$, where $\ensuremath{\mu}\ensuremath{\approx}1.25$, indicative of a superaging response.
Supersymmetry breaking through confining and dual theory gauge dynamics

Abstract We show that theories in the confining, free magnetic, and conformal phases can break supersymmetry through dynamical effects. To illustrate this, we present theories based on the gauge groups SU ( n ) × SU (4) × U (1) and SU ( n ) × SU (5) × U (1) with the field content obtained by decomposing an SU ( m ) theory with an antisymmetric tensor and m − 4 antifundamentals.
Solar influences on the cosmic ray intensity at high elevations

Abstract Instrument carrying balloon flights using the radio-cosmic-ray technique have been made during the day and the night, to investigate the amount of the diurnal variation at high altitudes. It was found that the effect, if any, is smaller than the experimental error of two per cent., and is estimated to be about 1.5 per cent. of the radiation at these levels. This permits a definite upper limit to be set to any contribution of solar origin to the ionization at levels up to 0.3 meters of water equivalent below the top of the atmosphere, which could be produced by photons in that spectral region to which mass-absorption laws apply, namely X-radiation. The magnitude of the effect is in agreement with the view advanced by Vallarta, that a magnetic field on the sun would produce a small diurnal change in the intensity of the softer portion of the cosmic ray intensity.
Timescales for planetary accretion and the structure of the protoplanetary disk

No self-consistent scenario for all stages of planetary accretion which satisfies observational constraints currently exists. An attempt is accordingly made here to resolve the timescale problems and to outline a planet formation scenario consistent with current theories of star formation as well as related models of the protoplanetary disk. For accretion to have proceeded in the manner presently hypothesized, the surface mass density of planetessimals would have had to to be relatively uniform in the Venus-Jupiter region of the protoplanetary disk, consistent with viscous accretion disk models of the solar nebula. The outer regions of the nebula would still have contained enough solid matter to account for the growth of Uranus and Neptune in 5 to 500 million years.
Optimal Function Computation in Directed and Undirected Graphs

We consider the problem of information aggregation in sensor networks, where one is interested in computing a function of the sensor measurements. We allow for block processing and study in-network function computation in directed graphs and undirected graphs. We study how the structure of the function affects the encoding strategies and the effect of interactive information exchange. Depending on the application, there could be a designated collector node, or every node might want to compute the function. We begin by considering a directed graph C = (γ. e) on the sensor nodes, where the goal is to determine the optimal encoders on each edge which achieve function computation at the collector node. Our goal is to characterize the rate region in R|e|, i.e., the set of points for which there exist feasible encoders with given rates which achieve zero-error computation for asymptotically large block length. We determine the solution for directed trees, specifying the optimal encoder and decoder for each edge. For general directed acyclic graphs, we provide an outer bound on the rate region by finding the disambiguation requirements for each cut, and describe examples where this outer bound is tight. Next, we address the scenario where nodes are connected in an undirected tree network, and every node wishes to compute a given symmetric Boolean function of the sensor data. Undirected edges permit interactive computation, and we therefore study the effect of interaction on the aggregation and communication strategies. We focus on sum-threshold functions and determine the minimum worst case total number of bits to be exchanged on each edge. The optimal strategy involves recursive in-network aggregation which is reminiscent of message passing. In the case of general graphs, we present a cut-set lower bound and an achievable scheme based on aggregation along trees. For complete graphs, we prove that the complexity of this scheme is no more than twice that of the optimal scheme.
Composite Dirac neutrinos

We present a mechanism that naturally produces light Dirac neutrinos. The basic idea is that the right-handed neutrinos are composite. Any realistic composite model must involve ‘hidden flavor’ chiral symmetries. In general some of these symmetries may survive confinement, and in particular, one of them manifests itself at low energy as an exact B − L symmetry. Dirac neutrinos are therefore produced. The neutrinos are naturally light due to compositeness. In general, sterile states are present in the model, some of them can naturally be warm dark matter candidates.
History of Ideas on the Cause of Earthquakes

Greek concepts of winds in the earth as the cause of earthquakes persisted until the latter part of the 19th century. The proportion of earthquakes believed to be caused by volcanic processes has progressively decreased. During the 19th century, faulting gradually emerged as the principal cause, becoming firmly established as a result of studies of the 1891 Mino-Owari and 1906 San Francisco earthquakes. With improvements in instrumentation, details of the mechanics of faulting became revealed by measurements of seismograms. It is now sometimes possible to estimate fault displacement, moment, the dimensions of displaced blocks, the velocity of rupture, and the location of the initiation of faulting from seismograms.
THE RADIAL VELOCITY DISTRIBUTION OF CLASS I AND FLAT-SPECTRUM PROTOSTARS

We analyze radial velocities for a sample of 31 Class I and flat-spectrum protostars in Taurus-Auriga, ? Ophiuchi, and Serpens for evidence of the global dynamical state of extremely young stellar populations buried within parental molecular clouds. Comparing the radial velocity of each protostar to that of the local CO gas, we are able to constrain the one-dimensional radial velocity dispersion of Class I and flat-spectrum objects to ~2.5 km s-1 or below. This upper limit to the protostellar velocity dispersion is consistent with the velocity dispersions of surrounding CO gas, which we measure to be ~1.4 km s-1, suggesting that the motions of protostars and local CO gas are dynamically linked and are dominated by the gravitational potential of the molecular cloud. However, the upper limit on the protostellar velocity dispersion could still allow for slightly inflated motions of protostars relative to the local molecular gas. Four of the protostars analyzed appear to have velocities more than 3 ? (7.5 km s-1) away from the central local CO gas velocity while showing spectroscopic indicators of youth and accretion such as H2 emission, H I Br? emission, or K-band continuum veiling. These radial velocity outliers may represent protostellar spectroscopic binaries or ejected cluster members.
On the Rate of Convergence of Finite-Difference Approximations for Elliptic Isaacs Equations in Smooth Domains

We show that there exists an algebraic rate of convergence of solutions of finite-difference approximations for uniformly elliptic Isaacs equations in smooth bounded domains.
Hilbert series of subspace arrangements

Abstract The vanishing ideal I of a subspace arrangement V 1 ∪ V 2 ∪ ⋯ ∪ V m ⊆ V is an intersection I 1 ∩ I 2 ∩ ⋯ ∩ I m of linear ideals. We give a formula for the Hilbert polynomial of I if the subspaces meet transversally. We also give a formula for the Hilbert series of the product ideal J = I 1 I 2 ⋯ I m without any assumptions about the subspace arrangement. It turns out that the Hilbert series of J is a combinatorial invariant of the subspace arrangement: it only depends on the intersection lattice and the dimension function. The graded Betti numbers of J are determined by the Hilbert series, so they are combinatorial invariants as well. We will also apply our results to generalized principal component analysis (GPCA), a tool that is useful for computer vision and image processing.
A survey for photometric variability from space

A survey for photometric variability in a wide variety of astronomical objects would produce much new information about their interiors and dynamics. Reasons for such a survey are given, as well as an example of the solar-constant variations that can be used as guide to what may be expected from main-sequence stars. A concept for a satellite dedicated to a survey of photometric variability is proposed.
Corporate Social Responsibility: Strategic Implications*

abstract We describe a variety of perspectives on corporate social responsibility (CSR), which we use to develop a framework for consideration of the strategic implications of CSR. Based on this framework, we propose an agenda for additional theoretical and empirical research on CSR. We then review the papers in this special issue and relate them to the proposed agenda.
EFFECTS OF FOREIGN INTELLECTUAL PROPERTY RIGHTS ON U.S. BILATERAL EXPORTS OF BIOTECHNOLOGY RELATED AGRICULTURAL INPUTS

This paper examines the effect of foreign intellectual property right (IPR) systems and the policies that comprise them on U.S. exports of biotechnology related agricultural input industries. Policy components include the extent of patent coverage across industry sectors, enforcement mechanisms, provisions for loss of patent protection, memberships to other international patent agreements, and duration of patent protection. Extending the empirical and theoretical work of Smith (2002), this paper uses a gravity model to analyze how IPRs affect the market power and market expansion effects of exports to countries with differing abilities to imitate technology. The findings suggest that strengthening global IPRs grant a market power effect to U.S. exporters; strong IPRs reduce U.S. exports by awarding a temporary monopoly over the protected good. However, the analysis of the individual policy components of an IPR system reveal which components inhibit trade through market power effects and which components counterbalance it through market expansion effects, increasing the flow of trade and access to biotechnology related agricultural inputs. Copyright 2003 by Suzanne L. W. Wisniewski. All rights reserved. Readers may make verbatim copies of this document for non-commercial purposes by any means, provided that this copyright notice appears on all such copies.
Overview of vector design for mammalian gene expression

The expression of cloned genes in mammalian cells is a basic tool for understanding gene expression, protein structure, and function, and biological regulatory mechanisms. The level of protein expression from heterologous genes introduced into mammlaian cells depends upon multiple factors including DNA copy number, efficiency of transportation, mRNA processing, mRNA transport, mRNA stability, and translational efficiency, and protein processing, transport, and stability. Different genes exhibit different rate limiting steps for efficient expression. Multiple strategies are available to obtain high level expression in mammalian cells. This article reviews vector design for expression of foreign genes in mammalian cells.
Complex versus real orthogonal polynomials of two variables

Orthogonal polynomials of two real variables can often be represented in complex variables. We explore the connection between the two types of representations and study the structural relations of complex orthogonal polynomials. The complex Hermite orthogonal polynomials and the disk polynomials are used as illustrating examples.
A Fast, Matrix-free Implicit Method for Compressible Flows on Unstructured Grids

A fast, matrix-free implicit method has been developed to solve the three-dimensional compressible Euler and Navier?Stokes equations on unstructured meshes. An approximate system of linear equations arising from the Newton linearization is solved by the GMRES (generalized minimum residual) algorithm with a LU-SGS (lower?upper symmetric Gauss?Seidel) preconditioner. A remarkable feature of the present GMRES+LU-SGS method is that the storage of the Jacobian matrix can be completely eliminated by approximating the Jacobian with numerical fluxes, resulting in a matrix-free implicit method. The method developed has been used to compute the compressible flows around 3D complex aerodynamic configurations for a wide range of flow conditions, from subsonic to supersonic. The numerical results obtained indicate that the use of the GMRES+LU-SGS method leads to a significant increase in performance over the best current implicit methods, GMRES+ILU and LU-SGS, while maintaining memory requirements similar to its explicit counterpart. An overall speedup factor from eight to more than one order of magnitude for all test cases in comparison with the explicit method is demonstrated.