cssi/SciSciGPT-SciSciNet huggingface dataset:
Flow instabilities and heat transfer in fluid overlying horizontal porous layers

Abstract Visualized flow fields and heat transfer experiments are reported for free convection in a cylindrical cavity filled with fluid-superposed porous layers, heated from below and cooled at the top. To examine the effects of porous layer height, thermal conductivity ratio, and Prandtl number, the experiments are conducted for acrylic, aluminum, and glass spheres with two kinds of silicone fluids and ethylene glycol. The complex relationship between Nusselt number and porous layer height as reported earlier (Prasad et al., 1989, 1990) remains unaltered with a variation in thermal conductivity ratio and/or Prandtl number. An increase in thermal conductivity of the solid matrix enhances the heat transfer rate, and a composite fluid and porous layer may transport more energy than the pure fluid alone provided the porous matrix is highly permeable and the solid-to-fluid conductivity ratio is large. The effect of Prandtl number seems to follow the trend reported for a cavity completely filled with the packed bed, particularly in high Darcy and Rayleigh number regimes.
DEMAZURE EMBEDDINGS ARE SMOOTH

We prove the conjecture of M. Brion stating that the closure of the orbit of a selfnormalizing spherical subalgebra in the corresponding Grassmanian is smooth.
Sensor Integration And Data Fusion

The problem of sensor integration and data fusion is addressed. We consider the problem of combining information from diversified sources in a coherent fashion. We assume that at the fusion, the information from various sensors may be available in different forms. For example, data from infrared (IR) sensors may be combined with range radar (RR) data, and further combined with visual images. In each case, the data and information from the different sensors are presented in a different format which may not be directly compatible for all sensors. Furthermore, the available information may be in the form of attributes and not dynamical measurements. A theory for sensor integration and data fusion that accommodates diversified sources of information is presented. Data (or, more generically, information) fusion may proceed at different levels, like the level of dynamics, the level of attributes, and the level of evidence. All different levels are considered and several practical examples of real world data fusion problems are discussed.
Virtual bronchoscopy for evaluation of malignant tumors of the thorax.

Abstract Objective: Virtual bronchoscopy is a novel technique making use of 3-dimensional reconstruction of 2-dimensional helical computed tomographic images for noninvasive evaluation of the tracheobronchial tree. This study was undertaken to evaluate the diagnostic potential of virtual bronchoscopy by comparing virtual bronchoscopic images with fiberoptic bronchoscopic findings in patients with thoracic malignant disease. Methods: Thirty-two consecutive patients with thoracic malignant tumors underwent virtual bronchoscopy for evaluation of suspected tracheobronchial lesions. For each virtual bronchoscopic examination, 200 to 300 contiguous 1.25-mm images of the thorax were obtained in only one or two 17-second breath holds by using a multislice computed tomographic scanner. Virtual bronchoscopy images were reconstructed and interpreted blind to the actual endoscopic findings. Results of virtual bronchoscopy were compared with fiberoptic bronchoscopic findings in 20 patients. Results: Anatomic computer simulation of the bronchial tree was successfully created in all patients. In 7 (35%) of 20 patients, results of fiberoptic bronchoscopy were found to be within normal limits. In all patients with normal anatomy, virtual bronchoscopy accurately correlated with the fiberoptic findings. Thirteen (65%) patients had a total of 22 abnormal findings on fiberoptic bronchoscopy. Virtual bronchoscopy detected 18 of 22 abnormal fiberoptic bronchoscopic findings: 13 of 13 obstructive lesions, 5 of 6 endoluminal lesions, and 0 of 3 mucosal lesions. The sensitivity of virtual bronchoscopy was 100% for obstructive lesions, 83% for endoluminal lesions, 0% for mucosal lesions, and 82% for all abnormalities; the specificity of virtual bronchoscopy was 100%. Conclusions: Preliminary evaluation indicates that virtual bronchoscopy may be a promising and noninvasive modality for identifying bronchial obstructions and endoluminal lesions, as well as for assessing the tracheobronchial tree beyond stenoses. However, at present, virtual bronchoscopy does not enable the detection of subtle mucosal lesions, and as such, this modality may not be appropriate for identifying premalignant lesions in the respiratory tract. Although fiberoptic bronchoscopy remains the standard modality for evaluating airway patency and mucosal lesions, virtual bronchoscopy may provide additional information that may be useful in the management of pulmonary malignant tumors. J Thorac Cardiovasc Surg 2002;123:967-72
Enhancing Cluster-based RFID Tag Localization using artificial neural networks and virtual reference tags

Abstract Construction sites are changing every day, which brings some difficulties for different contractors to do their tasks properly. One of the key points for all entities who work on the same site is the location of resources including materials, tools, and equipment. Therefore, the lack of an integrated localization system leads to an increase in the time wasted on searching for resources. In this research, a localization method based on Radio Frequency Identification (RFID) systems which does not need infrastructure is proposed to overcome this problem. This paper investigates the usage of active RFID technology for the localization of movable objects (e.g. components, equipment, and tools) equipped with RFID tags using handheld readers by extending a Cluster-based Movable Tag Localization (CMTL) technique which uses a k-Nearest Neighbor (k-NN) algorithm. CMTL uses a multidimensional clustering technique that considers signal pattern similarity between target and reference tags together with spatial distribution of reference tags for detecting the region where the target tag is located. The paper proposes applying an irregular bilinear interpolation method to form a grid of virtual reference tags within the selected cluster of real reference tags. Moreover, the proposed method uses artificial neural networks (ANNs) for positioning the target tag, as opposed to empirical weighted averaging formulas used in similar k-NN based methods. Comparative analysis is performed to quantify the improvement of the proposed method over similar k-NN-based methods using a simulation environment. A case study is performed to analyze the performance of the proposed method.
The direct contact problem in a trochoidal-type machine

Abstract Reducing the contact forces in a trochoidal-type machine is important because the machine cannot be adjusted for wear. The main difficulty in calculating the contact forces is to determine the forces that are transmitted through each contact point. Since there are many points of contact, at any instant, the problem is quasi-statically indeterminate and no satisfactory method of analysis is available in the current literature. The first part of this paper presents a simplified analytical model of a trochoidal-type machine when friction and deformation at the contact points are neglected. From this model, closed-form equations are derived for the normal contact forces. Then the second part of the paper presents a combined analytical and finite element model of the same machine. The analysis for both models is for quasi-static conditions. The results from the two models are compared and important conclusions are drawn.
Assessing the effects of violence on women in battering relationships with the Keane MMPI-PTSD Scale

The Minnesota Multiphasic Personality Inventory (MMPI)-Keane Posttraumatic Stress Disorder (PTSD) Scale (PK) has proven to be a reliable and valid measure of PTSD in combat veterans. However, few studies have examined the scale's validity in battered women, who often present with PTSD. Using empirically derived cutoff scores for the PK Scale, 69 battered women were assigned to PTSD-Positive and PTSD-Negative groups and then compared on measures of PTSD, distress, social support, and history of abuse in and out of the battering relationship. The PTSD-Positive group scored significantly higher across all measures of PTSD and distress, supporting the concurrent validity of the PK Scale in this population. However, the two groups differed only for the frequency of death threats, suggesting that the PK Scale is only mildly sensitive to the level of trauma exposure. Finally, lower levels of perceived social support were found in the PTSD-Positive than the PTSD-Negative group. Implications of these findings for the assessment of PTSD in battered women are discussed.
Non-coalescence of oppositely charged drops

The movement of drops in electric fields plays a role in processes as diverse as storm cloud formation, ink-jet printing and lab-on-a-chip manipulations. An important factor in practical applications is the tendency for adjacent drops to coalesce, usually assumed to be favoured if drops are oppositely charged and attracted to each other. Now Ristenpart et al. show that when oppositely charged drops move towards each other in an electric field whose strength exceeds a critical value, the drops simply 'bounce' off one another. This observation calls for a re-evaluation of our understanding of all processes involving electrically induced drop motion. Adjacent drops of fluid coalesce, and oppositely charged drops have long been assumed to experience an attractive force that favours their coalescence. However, here it is observed that oppositely charged drops moving towards each other in a strong electric field do not coalesce when the field strength exceeds a certain value but rather 'bounce' off one another. This observation calls for a re-evaluation of our understanding of processes such as storm cloud formation and ink-jet printing, which involve electrically induced droplet motion. Electric fields induce motion in many fluid systems, including polymer melts1, surfactant micelles2 and colloidal suspensions3. Likewise, electric fields can be used to move liquid drops4. Electrically induced droplet motion manifests itself in processes as diverse as storm cloud formation5, commercial ink-jet printing6, petroleum and vegetable oil dehydration7, electrospray ionization for use in mass spectrometry8, electrowetting9 and lab-on-a-chip manipulations10. An important issue in practical applications is the tendency for adjacent drops to coalesce, and oppositely charged drops have long been assumed to experience an attractive force that favours their coalescence11,12,13. Here we report the existence of a critical field strength above which oppositely charged drops do not coalesce. We observe that appropriately positioned and oppositely charged drops migrate towards one another in an applied electric field; but whereas the drops coalesce as expected at low field strengths, they are repelled from one another after contact at higher field strengths. Qualitatively, the drops appear to ‘bounce’ off one another. We directly image the transient formation of a meniscus bridge between the bouncing drops, and propose that this temporary bridge is unstable with respect to capillary pressure when it forms in an electric field exceeding a critical strength. The observation of oppositely charged drops bouncing rather than coalescing in strong electric fields should affect our understanding of any process involving charged liquid drops, including de-emulsification, electrospray ionization and atmospheric conduction.
Spontaneously broken Lorentz invariance in three-dimensional gauge theories

Abstract In a wide class of three-dimensional Abelian gauge theories with a bare Chern-Simons term, the Lorentz invariance is spontaneously broken by dynamical generation of a nonvanishing magnetic field. The originally massive photon becomes massless, fulfilling the role of a Nambu-Goldstone boson associated with the spontaneous breaking of the Lorentz invariance.
Magnetism at surfaces and interfaces

Abstract The current state-of-the-art of ab-initio calculations of the magnetic structures of surfaces and interfaces is highlighted by presenting results obtained with the recently developed full-potential linearized augmented plane wave method for thin films. In particular, spin density maps, (induced) magnetic moments and hyperfine-fields are presented for the clean metal surfaces Fe(001), Ni(001) and Pt(001). The magnetic moments on an interface are discussed for the prototypical case Ni/Cu.
A Scanning Electron Microscope Examination of Silver Cones Removed From Endodontically Treated Teeth

Twenty-five silver cones were removed from teeth which had been treated endodontically from 3 months to 20 years previously. Examination by the scanning electron microscope revealed that these cones were moderately to severely corroded. The corrosion patterns were described as ranging from pitting to deep crater formation with globular or spherical agglomerations. Examinations with the electron probe showed sulfur peaks on the corroded portions of the cones. X-ray diffraction analyses indicated that the chemical compounds formed were silver sulfides, silver sulfates, silver carbonates, and silver amine sulfate amide hydrates. Tissue culture studies indicated that the corrosion products were highly cytotoxic. The mechanisms for the formation of the corrosion products have been postulated as being due to plastic deformations and metal transfer to the silver cones, plus contact of the silver with tissue fluids.
Geometric algebra techniques for general relativity

Abstract Geometric (Clifford) algebra provides an efficient mathematical language for describing physical problems. We formulate general relativity in this language. The resulting formalism combines the efficiency of differential forms with the straightforwardness of coordinate methods. We focus our attention on orthonormal frames and the associated connection bivector, using them to find the Schwarzschild and Kerr solutions, along with a detailed exposition of the Petrov types for the Weyl tensor.
Extremal dependence analysis of network sessions

We refine a stimulating study by Sarvotham et al. (Comput Networks 48:335–350, 2005) which highlighted the influence of peak transmission rate on network burstiness. From TCP packet headers, we amalgamate packets into sessions where each session is characterized by a 5-tuple (S,D,R,R ∨ ,Γ)=(total payload, duration, average transmission rate, peak transmission rate, initiation time). After careful consideration, a new definition of peak rate is required. Unlike Sarvotham et al. (Comput Networks 48:335–350, 2005) who segmented sessions into two groups labelled alpha and beta, we segment into 10 sessions according to the empirical quantiles of the peak rate variable as a demonstration that the beta group is far from homogeneous. Our more refined segmentation reveals additional structure that is missed by segmentation into two groups. In each segment, we study the dependence structure of (S,D,R) and find that it varies across the groups. Furthermore, within each segment, session initiation times are well approximated by a Poisson process whereas this property does not hold for the data set taken as a whole. Therefore, we conclude that the peak rate level is important for understanding structure and for constructing accurate simulations of data in the wild. We outline a simple method of simulating network traffic based on our findings.
Characterization and stability of cyclic disulfides and cyclic dimeric bis(disulfides)

Abstract This paper describes the preparation of cyclic bis(disulfide) diners derived from trans -2-butene-1,4-dithiol and cis -1,2-cyclohexane dithiol and the cyclic tris(disulfide) dimer of 1,3,5-tris(mercaptomethyl)benzene by high dilution oxidation of the thiols with iodine. The stability toward ring-opening polymerization of these three new cyclic disulfides and of nine previously reported cyclic disulfides was tested by heating the disulfide with a catalytic amount of sodium methanethiolate. None of the cyclic bis(disulfides) were stable with respect to polymerization under these conditions. The results of these experiments, together with literature reports concerning the stability of similar disulfides, indicate that few simple alkyl disulfides are thermodynamically stable in cyclic form.
Splittings of generalized Baumslag–Solitar groups

We study the structure of generalized Baumslag–Solitar groups from the point of view of their (usually non-unique) splittings as fundamental groups of graphs of infinite cyclic groups. We find and characterize certain decompositions of smallest complexity (fully reduced decompositions) and give a simplified proof of the existence of deformations. We also prove a finiteness theorem and solve the isomorphism problem for generalized Baumslag–Solitar groups with no non-trivial integral moduli.
Coreless Terrestrial Exoplanets

Differentiation in terrestrial planets is expected to include the formation of a metallic iron core. We predict the existence of terrestrial planets that have differentiated but have no metallic core, planets that are effectively a giant silicate mantle. We discuss two paths to forming a coreless terrestrial planet, whereby the oxidation state during planetary accretion and solidification will determine the size or existence of any metallic core. Under this hypothesis, any metallic iron in the bulk accreting material is oxidized by water, binding the iron in the form of iron oxide into the silicate minerals of the planetary mantle. The existence of such silicate planets has consequences for interpreting the compositions and interior density structures of exoplanets based on their mass and radius measurements.
Superpotentials for vector bundle moduli

We present a method for explicitly computing the non-perturbative superpotentials associated with the vector bundle moduli in heterotic superstrings and M-theory. This method is applicable to any stable, holomorphic vector bundle over an elliptically fibered Calabi–Yau threefold. For specificity, the vector bundle moduli superpotential, for a vector bundle with structure group G=SU(3), generated by a heterotic superstring wrapped once over an isolated curve in a Calabi–Yau threefold with base B=F1, is explicitly calculated. Its locus of critical points is discussed. Superpotentials of vector bundle moduli potentially have important implications for small instanton phase transitions and the vacuum stability and cosmology of superstrings and M-theory.
The Meteorological Measurement System on the NASA ER-2 Aircraft

A Meteorological Measurement System (MMS) was designed and installed on one of the NASA high-altitude ER-2 aircraft (NASA 706). The MMS provides in situ measurements of free-stream pressure (+ or - 0.3 mb), temperature (+ or - 0.3 C), and wind vector (+ or - 1 m/s). It incorporates a high-resolution inertial navigation system specially configured for scientific applications, a radome differential pressure system for measurements of the airflow angles, and a compact, computer-controlled data acquisition system to sample, process and store 45 variables on tape and on disk. The MMS hardware and software development is described, and resolution and accuracy of the instrumentation discussed. Custom software facilitates preflight system checkout, inflight data acquisition, and fast postflight data download. It accommodates various modes of MMS data: analog and digital, serial and parallel, and synchronous and asynchronous. Flight results are presented to demonstrate the capability of the system.
SET-based nano-circuit simulation and design method using HSPICE

Abstract This paper presents a simulation and design method for complementary SET-based nano-circuits from a practical circuit design point of view. HSPICE behavioral implementation of modified Lientschnig's SET model based on the orthodox theory and the Birth–Death Markov chain is demonstrated and verified with Coulomb characteristics. It shows reduced CPU time, improvement of accuracy, and more compatibility with other SPICE softwares on both Windows and Unix platforms. The proposed design methodology presents how to build static CMOS-like SET circuits, and demonstrates that conventional CMOS circuit design methodologies are all applicable to SET circuit designs based on the methodology. HSPICE simulation results show that, for 1 MΩ junction resistance, the power consumption of a SET NAND2 gate is less than 0.3 pW, and the propagation delay for a SET XOR2 gate is 29.8 ns while driving a 10 aF load.
Justice forward: Tribes, climate adaptation and responsibility

Federally-recognized tribes must adapt to many ecological challenges arising from climate change, from the effects of glacier retreat on the habitats of culturally significant species to how sea leave rise forces human communities to relocate. The governmental and social institutions supporting tribes in adapting to climate change are often constrained by political obstructions, raising concerns about justice. Beyond typical uses of justice, which call attention to violations of formal rights or to considerations about the degree to which some populations may have caused anthropogenic climate change, a justice framework should guide how leaders, scientists and professionals of all heritages and who work with or for federally-recognized tribes understand what actions are morally essential for supporting tribes’ adaptation efforts. This paper motivates a shift to a forward-looking framework of justice. The framework situates justice within the systems of responsibilities that matter to tribes and many others, which range from webs of inter-species relationships to government-to-government partnerships. Justice is achieved when these systems of responsibilities operate in ways that support the continued flourishing of tribal communities.
Cappell-Shaneson homotopy spheres are standard

We show here that an infinite sequence of homotopy 4-spheres constructed by Cappell-Shaneson are all diffeomorphic to S 4 . This generalizes previous results of Akbulut-Kirby and Gompf.
Riesz s-equilibrium measures on d-dimensional fractal sets as s approaches d

Abstract Let A be a compact set in R p of Hausdorff dimension d. For s ∈ ( 0 , d ) , the Riesz s-equilibrium measure μ s , A is the unique Borel probability measure with support in A that minimizes the double integral over the Riesz s-kernel | x − y | − s over all such probability measures. In this paper we show that if A is a strictly self-similar d-fractal, then μ s , A converges in the weak-star topology to normalized d-dimensional Hausdorff measure restricted to A as s approaches d from below.
The DIRTY Model. I. Monte Carlo Radiative Transfer through Dust

We present the DIRTY (DustI Radiative Transfer, Yeah!) radiative transfer model in this paper and a companion paper. This model computes the polarized radiative transfer of photons from arbitrary distributions of stars through arbitrary distributions of dust using Monte Carlo techniques. The dust re-emission is done self-consistently with the dust absorption and scattering and includes all three important emission paths: equilibrium thermal emission, nonequilibrium thermal emission, and the aromatic features emission. The algorithm used for the radiative transfer allows for the efficient computation of the appearance of a model system as seen from any viewing direction. We present a simple method for computing an upper limit on the output quantity uncertainties for Monte Carlo radiative transfer models that use the weighted photon approach.
Single-snapshot robust direction finding

The paper presents a novel approach for recursively estimating the directions of arrival of incident signals as measurements are received along a sensor array. Using a single snapshot and without any statistical assumptions, the proposed method employs a robust performance criterion, which is based on worst-case gain minimization. The criterion aims to reduce the estimation error induced by worst-case amplitude and phase perturbations as well as additive noise in the array model. An algorithm that guarantees the criterion-within a first-order approximation-is developed and shown to converge. Moreover, instead of using a trial-and-error method to find a constant, minimum worst-case gain, the minimum worst-case gain is updated as each sensor measurement is processed. A step-by-step implementation of the algorithm is presented, and its computational complexity is analyzed. The performance of the new approach is evaluated by simulating the estimation algorithm for a linear array and comparing its performance with that of an existing single-snapshot algorithm.
The Rates of Type I X-Ray Bursts from Transients Observed with RXTE: Evidence for Black Hole Event Horizons

We measure the rates of type I X-ray bursts from a likely flux-limited sample of 37 nonpulsing Galactic transients observed with RXTE during 1996-2004. These sources are well categorized in the literature as either neutron star systems or black hole candidates. Our goals are to test the burst model for neutron stars and to investigate whether black holes have event horizons. Target selection is one of several differences between the present study and the investigation of the event horizon question by Tournear and coworkers. Burst rates are measured as a function of bolometric luminosity, and the results are compared with augmented versions of the burst model developed by Narayan & Heyl. For a given mass, we consider a range in both the radius and the temperature at the boundary below the accretion layer. We find 135 spectrally confirmed type I bursts in 3.7 Ms of PCA exposures for the neutron star group (13 sources), and the burst rate function is generally consistent with the model predictions. However, for the black hole groups (18 sources), there are no confirmed type I bursts in 6.5 Ms of exposure, and the upper limits in the burst function are inconsistent with the model predictions for heavy compact objects with a solid surface. The consistency probability is ~2 × 10-7 for dynamical black hole binaries, falling to 3 × 10-13 with the added exposures of black hole candidates. Furthermore, there are systematic spectral differences between the neutron star and black hole groups, supporting the presumption that physical differences underly the classifications in our sample. These results provide indirect evidence that black holes do have event horizons.
D-optimal Factorial Designs under Generalized Linear Models

Generalized linear models (GLMs) have been used widely for modeling the mean response both for discrete and continuous random variables with an emphasis on categorical response. Recently Yang, Mandal and Majumdar (2013) considered full factorial and fractional factorial locally D-optimal designs for binary response and two-level experimental factors. In this article, we extend their results to a general setup with response belonging to a single-parameter exponential family and for multilevel predictors.
Reflection centralizers in Coxeter groups

We refine Brink’s theorem, that the non-reflection part of a reflection centralizer in a Coxeter group W is a free group. We give an explicit set of generators for the centralizer, which is finitely generated when W is. And we give a method for computing the Coxeter diagram for its reflection subgroup. In many cases, our method allows one to compute centralizers in one’s head.
Automated Aircraft Scheduling Methods in the Near Terminal Area

A general scheduling algorithm for aircraft from terminal area entry to touchdown is developed. The method has the following novel features: (1) many speed classes of aircraft are considered and speed variations within classes and along portions of the flight path are permitted; (2) multiple paths are considered which may merge or diverge - the analysis is not restricted to a single runway nor to departures only; (3) landings are scheduled along conflict free flight paths in minimum time. The algorithm is currently being incorporated in a fast-time simulation of a STOL air traffic system.
Subsurface Circulations within Active Regions

Using high-resolution ring analysis, we deduce subsurface flows within magnetic active regions and within the quiet Sun. With this procedure, we are capable of measuring flows with a horizontal spatial resolution of 2° in heliographic angle (or roughly 20 Mm). From the resulting flow fields we deduce mean inflow rates into active regions, mean circulation speeds around active regions, and probability density functions (PDFs) of properties of the flow field. These analyses indicate that active regions have a zonal velocity that exceeds that of the quiet Sun at the same latitude by 20 m s–1, yet active regions advect poleward at the same rate as the quiet Sun. We also find that almost all active regions possess a mean inflow (20-30 m s–1) and a cyclonic circulation (5 m s–1) at their peripheries, whereas their cores, where the sunspots are located, are zones of strong anticyclonic outflow (50 m s–1). From the PDFs, we find that active regions modify the structure of convection with a scale greater than that of supergranulation. Instead of possessing an asymmetry between inflows and outflows (with a larger percentage of the surface occupied by outflows), as is seen in the quiet Sun, active regions possess symmetric distributions.
Natural Convection Along a Finite Vertical Plate

The discrepancy between the measured mean heat flux for natural convection on a finite vertical plate and the solution of Pohlhausen, Schmidt, and Beckmann has been known for a long time; no theoretical explanation has ever been provided. In this paper, a double-deck structure is introduced to account for the trailing-edge effect. This solution shows that the flow accelerates near the training edge due to the geometric discontinuity which leads to a decreased flow constraint. An inward normal flow is induced by the local flow acceleration and generates a change in the displacement of the thin viscous layer near the plate. Consequently a pressure disturbance is developed and transmits information upstream. The heat flux and wall shear stress both increase due to this flow acceleration. Even though the effect on the total heat flux is small, the local heat flux is modified substantially. Thus the smaller effects due to the leading edge, the displacement, and the wake cannot be the reason for the discrepancy.
Does the Fine-Structure Constant Vary with Cosmological Epoch?

We use the strong nebular emission lines of O III, ??5007 and 4959, to set a robust upper limit on the time dependence of the fine-structure constant. We find < 2 ? 10-13 yr-1, corresponding to ??/?(0) = ? 10-4 for quasars with 0.16 < z < 0.80 obtained from the SDSS Early Data Release. Using a blind analysis, we show that the upper limit given here is invariant with respect to 17 different ways of selecting the sample and analyzing the data. As a by-product, we show that the ratio of transition probabilities corresponding to the ??5007 and 4959 lines is 2.99 ? 0.02, in good agreement with (but more accurate than) theoretical estimates. We compare and contrast the O III emission line method used here with the many-multiplet method that was used recently to suggest evidence for a time-dependent ?. In an appendix we analyze the quasars from the recently available SDSS Data Release One sample and find ??/?(0) = ? 10-4.
High-resolution local gravity model of the south pole of the Moon from GRAIL extended mission data

We estimated a high-resolution local gravity field model over the south pole of the Moon using data from the Gravity Recovery and Interior Laboratory's extended mission. Our solution consists of adjustments with respect to a global model expressed in spherical harmonics. The adjustments are expressed as gridded gravity anomalies with a resolution of 1/6° by 1/6° (equivalent to that of a degree and order 1080 model in spherical harmonics), covering a cap over the south pole with a radius of 40°. The gravity anomalies have been estimated from a short-arc analysis using only Ka-band range-rate (KBRR) data over the area of interest. We apply a neighbor-smoothing constraint to our solution. Our local model removes striping present in the global model; it reduces the misfit to the KBRR data and improves correlations with topography to higher degrees than current global models. Key Points We present a high-resolution gravity model of the south pole of the Moon Improved correlations with topography to higher degrees than global models Improved fits to the data and reduced striping that is present in global models
The Economics of Water Quality

AbstractThis article surveys selected contributions of economics to the literature on water pollution and the regulation of water quality. While not a comprehensive review, the article highlights w...
Thermoacoustic Refrigerator for Space Applications

A new spacecraft cryocooler which uses resonant high-amplitude sound waves in inert gases to pump heat is described. The phasing of the thermoacoustic cycle is provided by thermal conduction. This "natural" phasing allows the entire refrigerator to operate with only one moving part (the loudspeaker diaphragm). A spacequalified thermoacoustic refrigerator was flown on the Space Shuttle Discovery (STS-42) in January, 1992. It was entirely autonomous, had no sliding seals, required no lubrication, used mostly low-tolerance machined parts, and contained no expensive components. Thermoacoustics is shown to be a competitive candidate for food refrigerator/freezers and commercial/residential air conditioners. The design and performance of the Space ThermoAcoustic Refrigerator (STAR) is described.
Shear Layer Flapping and Interface Convolution in a Separated Supersonic Flow

The steadiness and convolution of the interface between the freestream and recirculating/wake core regions in an axisymmetric, separated supersonic flow were studied using planar imaging. Five regions along the shear layer/wake boundary were investigated in detail to quantify the effects that key phenomena, such as the recompression and reattachment processes, have on the development of large-scale unsteady motions and interfacial convolution. These studies show that flapping motions, when viewed from the side, generally increase in magnitude, in relation to the local shear layer thickness, with downstream distance, except at the mean reattachment point, where they are slightly suppressed. When viewed from the end, the area-based (pulsing) fluctuations increase monotonically downstream as a percentage of the local area, whereas the position-based (flapping) motions show pronounced peaks in magnitude in the recompression region and in the developing wake. The interface convolution increases monotonically with downstream distance in both the side- and end-view orientations
Name disambiguation from link data in a collaboration graph using temporal and topological features

In a social community, multiple persons may share the same name, phone number or some other identifying attributes. This, along with other phenomena, such as name abbreviation, name misspelling, and human error lead to erroneous aggregation of records of multiple persons under a single reference. Such mistakes affect the performance of document retrieval, web search, database integration, and more importantly, improper attribution of credit (or blame). The task of entity disambiguation partitions the records belonging to multiple persons with the objective that each partition is composed of records of a unique person. Existing solutions to this task use either biographical attributes, or auxiliary features that are collected from external sources, such as Wikipedia. However, for many scenarios, such auxiliary features are not available, or they are costly to obtain. Besides, the attempt of collecting biographical or external data sustains the risk of privacy violation. In this work, we propose a method for solving entity disambiguation task from timestamped link information obtained from a collaboration network. Our method is non-intrusive of privacy as it uses only the graph topology of an anonymized network. Experimental results on two real-life academic collaboration networks show that the proposed method has satisfactory performance.
Dynamic across-time measurement interpretation

Abstract Incrementally maintaining a qualitative understanding of physical system behavior based on observations is crucial to tasks such as real-time control, monitoring, and diagnosis. This paper describes the DATMI theory for interpretation tasks. The key idea of DATMI is to dynamically maintain a concise representation of the space of local and global interpretations across time that are consistent with the observations. This representation has two key advantages. First, a set of possible interpretations is more useful than a single (best) candidate for many tasks, such as conservative monitoring. Second, this representation simplifies switching to alternative interpretations when data are faulty or incomplete. Domain-specific knowledge about state and transition probabilities can be used to suggest the interpretation which is most likely. Domain-specific knowledge about durations of states and paths of states can also be used to further constrain the interpretation space. When no consistent interpretation exists, faulty-data hypotheses are generated and then tested by adjusting the interpretation space. The DATMI theory has been tested via implementation and we describe its performance on two examples.
Response of Flight Vehicles to Nonstationary Atmospheric Turbulence

Nonstationary random analysis of flight vehicle response to atmospheric turbulence, using Priestley evolutionary spectral method
Maximal codeword lengths in Huffman codes

In this paper, we consider the following question about Huffman coding, which is an important technique for compressing data from a discrete source. If p is the smallest source probability, how long, in terms of p, can the longest Huffman codeword be? We show that if p is in the range 0 < p ≤ 12, and if K is the unique index such that 1FK+3 < p ≤ 1FK+2, where FK denotes the Kth Fibonacci number, then the longest Huffman codeword for a source whose least probability is p is at most K, and no better bound is possible. Asymptotically, this implies the surprising fact that for small values of p, a Huffman code's longest codeword can be as much as 44% larger than that of the corresponding Shannon code.
Monte Carlo simulation of re-entry flows using a bimodal vibration model

The role of vibration-dis sociation coupling in flows representative of aeroassisted transfer vehicles with afterbodies is considered. The physical model employed is motivated by the recent work of Sharma et al.4 In this model, a bimodal representation, determined by the vibrational levels, is assumed for each diatomic molecule. Only molecules in the upper states are allowed to dissociate. The model is incorporated into the direct simulation Monte Carlo method of Bird and used to calculate steady flows past two geometries: a 5-deg blunt wedge and the project Fire configuration. Five chemical species are considered. It is shown that the new model results in reduced dissociation. Moreover, the convective heating rate increases for a finite catalytic wall and is essentially the same for a fully catalytic wall. Finally, for the conditions studied, the effect of the afterbody on the pressure distribution, heat transfer, and skin friction is minimal.
Fast Estimator of Primordial Non-Gaussianity from Temperature and Polarization Anisotropies in the Cosmic Microwave Background

Measurements of primordial non-Gaussianity (fNL) open a new window onto the physics of inflation. We describe a fast cubic (bispectrum) estimator of fNL, using a combined analysis of temperature and polarization observations. The speed of our estimator allows us to use a sufficient number of Monte Carlo simulations to characterize its statistical properties in the presence of real-world issues such as instrumental effects, partial sky coverage, and foreground contamination. We find that our estimator is optimal, where optimality is defined by saturation of the Cramer-Rao bound, if noise is homogeneous. Our estimator is also computationally efficient, scaling as O(N3/2), compared to the O(N5/2) scaling of the brute-force bispectrum calculation for sky maps with N pixels. For Planck this translates into a speedup by factors of millions, reducing the required computing time from thousands of years to just hours and thus making fNL estimation feasible for future surveys.
Satellite-aided land mobile radio experiments, applications and problems☆

Abstract Radio communications between vehicles or individuals and base stations are essential to many public safety, law enforcement and commercial users in urban areas. Present day communications are limited to nearly line-of-sight distances from the vehicle or hand portable units to a base station or repeater. It is probable that many potential users in rural, remote and offshore areas would benefit if the communications were available everywhere on land and territorial waters. Geosynchronous satellites can serve as repeaters for mobile and personal radios, and they appear to be a cost effective means of providing the service. Voice bandwidth communication and automatic position monitoring of an automobile were tested using the VHF transponders of NASAs ATS-3 and ATS-1 satellites. Voice communications were reliable and position fixes were accurate to one fourth mile, with 0.3 mile precision of individual fixes. Demonstrations for potential users have included emergency medical voice and telemetry communications between ambulances and hospitals. While technical feasibility of satellite-aided mobile and personal communications has been demonstrated, and its potential value is appreciated by a small segment of the user community, many problems remain before an operational system could be implemented. Solutions to the problems require an experimental satellite with a multibeam antenna. The satellite or its associated ground terminals should incorporate computer controlled network switching to test demand assignment of channels. Prolonged experience by many users of the experimental satellite in their routine operations would aggregate user needs and define the capital investment that would be justified to implement a commercial operating system.
Stability and slicing inequalities for intersection bodies

We prove a generalization of the hyperplane inequality for intersection bodies, where volume is replaced by an arbitrary measure μ with even continuous density and sections are of arbitrary dimension n − k, 1 ≤ k < n. If K is a generalized k-intersection body, then $$\mu(K)\,\leq\,\frac{n}{n-k}c_{n,k} \max_{H} \mu(K\cap H) {\rm Vol}_n(K)^{k/n}.$$ Here \({c_{n,k} = |B_2^n|^{(n-k)/n}/|B_2^{n-k}| 0 ,\ 1\le k < n}\) . Suppose that K and L are origin-symmetric star bodies in \({\mathbb{R}^{n}}\) , and K is a generalized k-intersection body. If for every (n − k)-dimensional subspace H of \({\mathbb{R}^{n}}\) $$\mu(K\cap H)\leq \mu(L\cap H)+\varepsilon,$$ then $$\mu(K)\leq \mu(L) +\frac{n}{n-k}c_{n,k} {\rm Vol}_n(K)^{k/n} \varepsilon.$$
Model for the hydrogen atom flux developed in a microwave plasma jet under diamond synthesis conditions

Abstract A model is summarized for the hydrogen atom flux in the effluent of a quartz flow tube which is fed by pure molecular hydrogen and which traverse a waveguide excited at microwave (m.w.) frequency. The high subatmospheric pressure, moderate power, convection-dominated conditions modeled are typical of the plasma jet processes for chemically vapor deposited (CVD) diamond. The plasma sustained in the flow tube is predicted to be ‘thermal” in the sense that thermal dissociation of molecular hydrogen strongly dominates dissociation by electron impact, but not in the sense of rough equality of gas and electron temperatures. Both the m.w. power absorbed by the plasma and the incident m.w. power, minimized by adjustment of a movable short circuit which terminates the waveguide, are determined as functions of atom flux for several values of the parameters (pressure and flow rate) which affect transport of the atoms to the substrate.
Trajectory and distribution of suspended non-Brownian particles moving past a fixed spherical or cylindrical obstacle

We investigate the motion of a suspended non-Brownian sphere past a fixed cylindrical or spherical obstacle in the limit of zero Reynolds number for arbitrary particle–obstacle aspect ratios. We consider both a suspended sphere moving in a quiescent fluid under the action of a uniform force as well as a uniform ambient velocity field driving a freely suspended particle. We determine the distribution of particles around a single obstacle and solve for the individual particle trajectories to comment on the transport of dilute suspensions past an array of fixed obstacles. First, we obtain an expression for the probability density function governing the distribution of a dilute suspension of particles around an isolated obstacle, and we show that it is isotropic. We then present an analytical expression – derived using both Eulerian and Lagrangian approaches – for the minimum particle–obstacle separation attained during the motion, as a function of the incoming impact parameter, i.e. the initial offset between the line of motion far from the obstacle and a parallel line that goes through its centre. Further, we derive the asymptotic behaviour for small initial offsets and show that the minimum separation decays exponentially. Finally we use this analytical expression to define an effective hydrodynamic surface roughness based on the net lateral displacement experienced by a suspended sphere moving past an obstacle.
Iridium-Catalyzed (Z)-Trialkylsilylation of Terminal Olefins

A complex of commercial [Ir(OMe)(cod)]2 and 4,4-di-tert-butyl-2,2-bipyridine (dtbpy) catalyzes the Z-selective, dehydrative silylation of terminal alkenes, but not 1,2-disubstituted alkenes, with triethylsilane or benzyldimethylsilane in THF at 40 °C. Yields and Z-stereoselectivity were significantly improved by 2-norbornene, in contrast with other sacrificial alkenes. The reaction is compatible with many functional groups including epoxides, ketones, amides, alcohols, esters, halides, ketals and silanes. a,b-Unsaturated esters were unreactive. The reaction probably proceeds through a Heck-type mechanism.
Quantum diagrams and quantum networks

This paper explores how diagrams of quantum processes can be used for modeling and for quantum epistemology.
EDTA Removes Formation Damage at Prudhoe Bay

Formation damage has been observed in some wells of the Prudhoe Bay field. Laboratory and field testing confirmed that the primary cause of damage was the buildup of calcium carbonate scale either in the perforation tunnels or in the formation sandstone near the wellbore. Conventional acid treatments could dissolve this scale, but scale reprecipitation from the spent acid caused rapid productivity decline. A scale-removal treatment with Na/sub 2/H/sub 2/ ethylenediaminetetraacetic acid (EDTA) has been developed that can effectively dissolve scale and chelate the dissolved metal ions. Chelation of the dissolved scale prevents scale reprecipitation. Of the 25 Prudhoe Bay wells acidized with EDTA through June 1982, 19 responded with significant productivity increases. In 17 of these wells, productivity has been sustained after treatment.
Linear Theory of Lower Hybrid Heating

The linear theory of wave propagation in the lower hybrid range of frequencies is presented. The topics of accessibility, linear and quasi-linear theories of electron Landau damping, and the linear theory of ion Landau damping are covered. The theory of wave propagation is extended to include the effect of toroidal geometry. A simulation model incorporating these theories is described and numerical results obtained with the model are given.