cssi/SciSciGPT-SciSciNet huggingface dataset:
A study of design options for a building integrated photovoltaic/thermal (BIPV/T) system with glazed air collector and multiple inlets

Abstract In this paper, a prototype open loop air-based building integrated photovoltaic thermal BIPV/T system with a single inlet is studied through a comprehensive series of experiments in a full scale solar simulator recently built at Concordia University. A numerical control volume model is developed and validated based on the results from the experiments. Improved designs of a BIPV/T system with multiple inlets and other means of heat transfer enhancement are studied through simulations. Simulation results indicate that the application of two inlets on a BIPV/T collector increases thermal efficiency by about 5% and increases electrical efficiency marginally. An added vertical glazed solar air collector improves the thermal efficiency by about 8%, and the improvement is more significant with wire mesh packing in the collector by an increase of about 10%. The developed model is applied to a BIPV/T roof of an existing solar house with four simulated inlets, and the thermal efficiency is improved by 7%.
Response of a tethered aerostat to simulated turbulence

Abstract Aerostats are lighter-than-air vehicles tethered to the ground by a cable and used for broadcasting, communications, surveillance, and drug interdiction. The dynamic response of tethered aerostats subject to extreme atmospheric turbulence often dictates survivability. This paper develops a theoretical model that predicts the planar response of a tethered aerostat subject to atmospheric turbulence and simulates the response to 1000 simulated hurricane scale turbulent time histories. The aerostat dynamic model assumes the aerostat hull to be a rigid body with non-linear fluid loading, instantaneous weathervaning for planar response, and a continuous tether. Galerkin’s method discretizes the coupled aerostat and tether partial differential equations to produce a non-linear initial value problem that is integrated numerically given initial conditions and wind inputs. The proper orthogonal decomposition theorem generates, based on Hurricane Georges wind data, turbulent time histories that possess the sequential behavior of actual turbulence, are spectrally accurate, and have non-Gaussian density functions. The generated turbulent time histories are simulated to predict the aerostat response to severe turbulence. The resulting probability distributions for the aerostat position, pitch angle, and confluence point tension predict the aerostat behavior in high gust environments. The dynamic results can be up to twice as large as a static analysis indicating the importance of dynamics in aerostat modeling. The results uncover a worst case wind input consisting of a two-pulse vertical gust.
Regular cell complexes in total positivity

Fomin and Shapiro conjectured that the link of the identity in the Bruhat stratification of the totally nonnegative real part of the unipotent radical of a Borel subgroup in a semisimple, simply connected algebraic group defined and split over \({\mathbb{R}}\) is a regular CW complex homeomorphic to a ball. The main result of this paper is a proof of this conjecture. This completes the solution of the question of Bernstein of identifying regular CW complexes arising naturally from representation theory having the (lower) intervals of Bruhat order as their closure posets. A key ingredient is a new criterion for determining whether a finite CW complex is regular with respect to a choice of characteristic maps; it most naturally applies to images of maps from regular CW complexes and is based on an interplay of combinatorics of the closure poset with codimension one topology.
Freezing and survival of insects at low temperatures

The literature on the general subject of freezing and survival both in plants and in animals is briefly reviewed and a bibliography given. Insects representing three ecological groups, (1) the oak borers—exposed to temperature extremes normally; (2) stored-products insects representing supposedly a tropical or subtropical group, and, (3) aquatic insects never exposed to temperatures lower than 0°C., were chosen for this study. Determinations of the freezing and undercooling points were made during the yearly cycle. Both the stored-products insects and the aquatic insects studied showed no periodicity in freezing or undercooling. The oak borers showed marked periodicity. The freezing-point varies directly with the moisture content. Cold-hardiness was produced experimentally by, (1) exposure of insects to low temperatures and, (2) by dehydration. Loss of cold-hardiness was produced experimentally by combinations of high temperature, food, and high relative humidity. The freezing-point ordinarily found corresponds with that of the blood. Repeated freezings of the same insect or tissue showed no hysteresis. There exists in certain insects a secondary freezing-point below that ordinarily found. Oak borers in summer condition die at the first freezing-point; in fully hardened condition they die at the secondary freezingpoint.
Regression with missing X’s: A review

Abstract The literature of regression analysis with missing values of the independent variables is reviewed. Six classes of procedures are distinguished: complete case analysis, available case methods, least squares on imputed data, maximum likelihood, Bayesian methods, and multiple imputation. Methods are compared and illustrated when missing data are confined to one independent variable, and extensions to more general patterns are indicated. Attention is paid to the performance of methods when the missing data are not missing completely at random. Least squares methods that fill in missing X's using only data on the X's are contrasted with likelihood-based methods that use data on the X's and Y. The latter approach is preferred and provides methods for elaboration of the basic normal linear regression model. It is suggested that more widely distributed software is needed that advances beyond complete-case analysis, available-case analysis, and naive imputation methods. Bayesian simulation methods and mu...
A novel technique for the reduction of capacitance spread in high-Q SC circuits

A novel realization of a switched-capacitor (SC) integrator is proposed. The integrator attenuates the input during both clock phases, so that the time constant of the integrator is realized with the product of two capacitance ratios instead of a single capacitance ratio. The capacitance spread only increases as the square root of the time constant. This integrator is stray-insensitive. The influence of the finite DC-amplifier gain and dynamic settling is the same as in conventional SC integrators. A low-pass notch SC biquad is presented as an example to show the capacitance advantage of the integrator. The example also shows that the increase of amplifier offset is small if the total offset of the entire SC filter is considered. It is shown that the SC low-pass notch biquad reduces the total capacitance by a factor of more than three. >
Is there a majority to support a capital tax cut

Abstract A capital income tax cut must in general be financed by increasing other taxes, and thus will have redistributive effects. This paper studies analytically the redistribution implied by a capital income tax cut in the Ramsey–Cass–Koopmans neoclassical growth model when agents differ in wealth and human capital and markets are frictionless. A few parameters affect the efficiency costs and redistributive benefits of capital taxation, and determine the set of agents who are in favor of a capital income tax cut. For plausible parameter values, a majority would lose from the tax cut, i.e. high capital taxes may be politically sustainable.
Improved depth lower bounds for small distance connectivity

We consider the problem of determining, given a graph G with specified nodes s and t, whether or not there is a path of at most k edges in G from s to t. We show that solving this problem on polynomialsize unbounded fan-in circuits requires depth $ \Omega{\rm(log\,log}\,k) $ , improving on a depth lower bound of $ \Omega{\rm(log^*}\,k) $ when $ k = {\rm log}^{O(1)}n $ given by Ajtai (1989), Bellantoni et al. (1992). More generally, we obtain an improved size-depth tradeoff lower bound for the problem for all $ k \le {\rm log}\,n $ .¶The key to our technique is a new form of “switching lemma” which combines some of the features of iteratively shortening terms due to Furst et al. (1984) and Ajtai (1983) with the features of switching lemma arguments introduced by Yao (1985), Hastad (1987), and Cai (1986) that have been the methods of choice for subsequent results.
JOB ATTITUDES AND EMPLOYEE MOTIVATION: THEORY, RESEARCH, AND PRACTICE

Industrial psychologists have been seriously concerned with the measurement, interpretation and implications of job attitudes ever since the Western Electric Studies (Roethlisberger and Dickson, 1939). When Herzberg et al. (1957) reviewed the literature as of 1955, they pointed out that there were severed thousand studies in the psychological literature that were concerned with job attitudes. At the present time there must be at least five thousand studies in the literature. Most of these job attitude studies have had as their major focus job satisfaction.
Cyclopropane hydrogenolysis on clean and chemically modified Mo(100) surfaces

Catalytic hydrogenolysis of cyclopropane (CP) to propane, ethane, and methane has been investigated over initially clean Mo(100) single-crystal surfaces and over surfaces chemically modified by adsorbed carbon, oxygen, and sulfur. Catalyst preparation was performed in ultrahigh vacuum with surface characterization by LEED and Auger. Catalytic hydrogenolysis under 1 atm pressure was monitored by gas chromatography. Initially clean Mo(100) surfaces and surfaces modified by 1 ML of atomic carbon or oxygen are active for single hydrogenolysis to propane and double hydrogenolysis to ethane and methane. The Mo(100) surface with 0.8 ML of sulfur is completely inactive. The reaction is first order in hydrogen and zero order in CP. The activation energy, determined from Arrhenius plots over the temperature range 300–523 K, is 37 ± 4 kJ/mol and is the same for all active surfaces. The product distribution (ca. 17% CH4, 17% C2H6, and 66% C3H8) is also the same for all active surfaces and is independent of temperature. The initially clean Mo(100) surface is ca. five times more active than either the carbon- or oxygen-modified surfaces which have approximately the same activity. Since the selectivity of CP hydrogenolysis has previously been shown to be sensitive to Mo chemical state, the data indicate that the same catalytic site is operative on all active surfaces. Comparison to literature data for supported Mo catalysts indicates that the observed selectivity is characteristic of low-valent Mo rather than of the oxide or carbide. Prior knowledge that adsorbed carbon and oxygen block fourfold hollow sites on the (100) crystal plane coupled with the higher activity observed for initially clean Mo(100) suggests (1) that the active sites for hydrogenolysis are open fourfold hollows and (2) that the open hollow sites are present as defects on the carbon- or oxygen-modified surfaces. The catalysts are inactive for hydrogenolysis of propane, indicating that CH4 and C2H6 are primary products. Likewise, propene is not an intermediate since propene conversion in H2 is exclusively to propane and metathesis products. The absence of the C4 products of metathesis from cyclopropane suggests that hydrogenolysis does not proceed via a metallacyclobutane surface intermediate. Therefore, the most likely mechanism involves a 1,3-diadsorbed surface intermediate.
Molecular Hydrogen Optical Depth Templates for FUSE Data Analysis

The calculation and use of molecular hydrogen optical depth templates to quickly identify and model molecular hydrogen absorption features longward of the Lyman edge at 912 Angstroms are described. Such features are commonly encountered in spectra obtained by the Far Ultraviolet Spectroscopic Explorer and also in spectra obtained by the Space Telescope Imaging Spectrograph, albeit less commonly. Individual templates are calculated containing all the Lyman and Werner transitions originating from a single rotational state (J'') of the 0th vibrational level (v'') of the ground electronic state. Templates are provided with 0.01 Angstrom sampling for doppler parameters ranging from 2 <= b <= 20 km s^-1 and rotational states 0 <= J'' <= 15. Optical depth templates for excited vibrational states are also available for select doppler parameters. Each template is calculated for a fiducial column density of log[N(cm^-2)] = 21 and may be scaled to any column less than this value without loss of accuracy. These templates will facilitate the determination of the distribution of molecular hydrogen column density as a function of rotational level. The use of these templates will free the user from the computationally intensive task of calculating profiles for a large number of lines and allow concentration on line profile or curve-of-growth fitting to determine column densities and doppler parameters. The templates may be downloaded freely from http://www.pha.jhu.edu/~stephan/h2ools2.html
(S)quark masses and non-Abelian horizontal symmetries

Abstract We present a model of quark and squark masses which is based on a non-Abelian horizontal symmetry. It leads to order of magnitude relations between quark mass ratios and mixing angles and to the successful exact relation sin θ C = m d m s to better than 20% accuracy. The non-Abelian symmetry also ensures the necessary squark degeneracy to suppress FCNC mediated by loops with squarks and gluinos, in the neutral meson systems.
SPECTRAL CALIBRATION AND KINEMATIC PROPERTIES OF THE FIELD HORIZONTAL BRANCH STARS

An understanding of the kinematic properties of the Galactic halo is an essential component to the ultimate understanding of the Galactic formation history. The blue field horizontal branch stars (FHB) are excellent stellar probes with which to explore these properties. The FHB stars are both intrinsically luminous, which allows kinematic exploration beyond the confines of the local solar neighborhood, and numerous, which is important for good statistical results. In the past, however, isolating a pure sample of FHB stars from their main sequence, A-star, counter-parts has proven to be a difficult and highly uncertain task leaving the FHB kinematic results open to skepticism. This dissertation explores the kinematic properties of an FHB sample identified through the use of a new spectral calibration technique. Follow up medium resolution (1-2 A), low S/N (10 4 kpc, and [Fe/H] [Fe/H] > -2.2.
Detection of the lunar body tide by the Lunar Orbiter Laser Altimeter

The Lunar Orbiter Laser Altimeter instrument onboard the Lunar Reconnaissance Orbiter spacecraft collected more than 5 billion measurements in the nominal 50 km orbit over ~10,000 orbits. The data precision, geodetic accuracy, and spatial distribution enable two-dimensional crossovers to be used to infer relative radial position corrections between tracks to better than ~1 m. We use nearly 500,000 altimetric crossovers to separate remaining high-frequency spacecraft trajectory errors from the periodic radial surface tidal deformation. The unusual sampling of the lunar body tide from polar lunar orbit limits the size of the typical differential signal expected at ground track intersections to ~10 cm. Nevertheless, we reliably detect the topographic tidal signal and estimate the associated Love number h2 to be 0.0371 ± 0.0033, which is consistent with but lower than recent results from lunar laser ranging.
Mixing under monotone censoring

We initiate the study of mixing times of Markov chain under monotone censoring. Suppose we have some Markov Chain $M$ on a state space $\Omega$ with stationary distribution $\pi$ and a monotone set $A \subset \Omega$. We consider the chain $M'$ which is the same as the chain $M$ started at some $x \in A$ except that moves of $M$ of the form $x \to y$ where $x \in A$ and $y \notin A$ are {\em censored} and replaced by the move $x \to x$. If $M$ is ergodic and $A$ is connected, the new chain converges to $\pi$ conditional on $A$. In this paper we are interested in the mixing time of the chain $M'$ in terms of properties of $M$ and $A$. Our results are based on new connections with the field of property testing. A number of open problems are presented.
Spectral State Transitions of the Ultraluminous X-Ray Sources X-1 and X-2 in NGC 1313

X-ray spectral state transitions are a key signature of black hole X-ray binaries and follow a well-defined pattern. We examined 12 XMM-Newton observations of the nearby spiral galaxy NGC 1313, which harbors two compact ultraluminous X-ray sources (ULXs), X-1 and X-2, in order to determine if the state transitions in ULXs follow the same pattern. For both sources, the spectra were adequately fitted by an absorbed power law with the addition of a low-temperature (kT = 0.1-0.3 keV) disk blackbody component required in six of the 12 observations. As the X-ray luminosity of X-1 increases to a maximum at 3 × 1040 ergs s-1, the power-law photon index softens to 2.5-3.0. This behavior is similar to the canonical spectral state transitions in Galactic black hole binaries, but the source never enters the high/soft or thermal-dominant state and instead enters the steep power-law state at high luminosities. X-2 has the opposite behavior and appears to be in the hard state, with a photon index of Γ = 1.7-2.0 at high luminosity, but can soften to Γ = 2.5 at the lower luminosities.
Concentration-price relations in regional fed cattle markets

Since 1977, the U.S. beef packing industry has been restructured at a pace unprecedented in large American industries. By 1987, four packers slaughtered over two-thirds of all steers and heifers. In the thirteen regional feedlot-packer markets studied here, the four leading packers slaughtered 85 percent of fed cattle, on average. The impact of packer concentration on fed cattle prices during 1971–86 was examined using several econometric models. The results generally support the hypothesis that packer concentration was negatively related to live cattle prices. Cattle prices were estimated to be about 3 percent less in the most concentrated region compared to the least concentrated region. There was evidence of a critical concentration of CR4=60 in regional livestock markets.
Percolation model for simulation of char oxidation and fragmentation time-histories

Abstract A simulation model of char oxidation is introduced in which char particles are represented by randomly generated clusters of bonds on a lattice. Realizations are generated by means of a percolation algorithm. Bonds in contact with the ambience burn at a mean rate which depends on cluster size. By adjusting parameters governing this size dependence and the initial cluster size, simulated burning-rate time-histories are obtained which reproduce previously reported features of single-particle time-histories measured experimentally. The principal features are sharp increases in the burning rate, previously interpreted and here modeled as fragmentation events. Fragmentation is modeled as the separation of a cluster into disconnected pieces due to bond burnout. The agreement with experimental data lends support to this “percolative fragmentation” mechanism. The computations indicate the importance of the fragmentation process with regard to both its impact on the average burning time and its contribution to the production of fine particles.
Establishment of a fabrication and measurement capability for aperture-fed stacked patch microstrip antennas at the Air Force Institute of Technology

A study was conducted to provide the Air Force Institute of Technology with the capability to fabricate and readily measure aperture-fed stacked patch microstrip antennas. It was determined that available facilities and equipment at the Cooperative Electronics and Materials Laboratory designed for photo-etching silicon wafers can be used to successfully etch microstrip antenna components. A small anechoic chamber dedicated to antenna pattern measurements was constructed. Measurement emphasis was placed on the antenna's principal plane radiation patterns, as well as on its VSWR bandwidth. Although the fabricated antenna did not operate optimally due to under-cutting during the etching process, the measurement results clearly show the broader bandwidth characteristic of the stacked patch design. >
Interfacing people with their machines

As computer technology proliferates, the techniques applied to the interface of people with their machines will assume great importance if the large dollar investments in equipment are to be recouped in the form of increased productivity.This paper propounds the theory that change in any form is difficult for people to accept, especially in the office environment, and that it is essential to involve the work force in the change to automated information processing if new technology is to succeed.The paper outlines several ways to accomplish this, including polls and individual interviews with all employees before the system is purchased and the design of a public relations effort to help employees understand the applications of automation to their personal roles. The paper also covers various ergonomic questions related to computer systems, such as noise, heat, illumination, static, terminal design, and general environmental questions.The issue of accommodating people in an office to office automation is a complex one, requiring a concerted effort on the part of all managers involved with the implementation.
NAS parallel benchmark results

Benchmark results for the Numerical Aerodynamic Simulation (NAS) Program at NASA Ames Research Center, which is dedicated to advancing the science of computational aerodynamics are presented. The benchmark performance results are for the Y-MP, Y-MO EL, and C-90 systems from Cray Research; the TC2000 from Bolt Baranek and Newman; the Gamma iPSC/860 from Intel; the CM-2, CM-200, and CM-5 from Thinking Machines; the CS-1 from Meiko Scientific; the MP-1 and MP-2 from MasPar Computer; and the KSR-1 from Kendall Square Research. The results for the MP-1 and -2, the KSR-1, and the CM-5 have not been published before. Many of the other results are improved from previous listings, reflecting improvements both in compilers and in implementations. >
A Multidisciplined Approach to Designing Targets for Horizontal Wells

A multidisciplined approach to developing 3D target diagrams and their associated tolerances provides a cost-effective method for designing horizontal wells. The key to this approach is that the diagram quantifies and communicates the uncertainty of the target boundary conditions to others involved in designing and drilling a well. Field examples show how a multidisciplined team creates a 3D target diagram. The preliminary 3D diagram is used to examine the combined uncertainty in the position of the features constraining the target. To maximize the target size, the team must decide on the relative importance of each constraining feature and assign target tolerance limits. The final target diagram minimizes both risk and cost to produce the optimum well design.
Reaction of Zirconia with Silica at the Stoichiometry of Zircon

Zirconia was combined with silica and halide mineralizers and fired in a nitrogen atmosphere. X-ray analysis showed zircon was formed, demonstrating that an oxygen atmosphere is not necessary for the formation of zircon. The reaction mechanism is the same as that forming zircon in air, involving transport of the silica as a volatile halide, followed by diffusion of silica and oxygen across the product layer to a reaction site on the zirconia.
Psychophysical generation of matching images for cross‐media color reproduction

A technique was developed and tested for generating CRT pictorial image reproductions that match the color appearance of print originals. Five observers, experienced in using Adobe Photoshop to adjust images, matched two scenes using a memory-matching technique Observers were able to produce accurate matches when originals and reproductions were viewed at the same white point. Observers then matched the reproductions at 6500 K to originals viewed at 9300 and 3000 K. These matches were compared to the predictions of various color-appearance models, using a paired-comparison technique in a psychophysical experiment using different observers. The observer-matched images were found to be equal or superior to matches produced using any of the models.
From Global Knowledge to Global Civic Engagement.

In this article, I argue that student learning is enhanced when civic engagement is a component of international education initiatives. When only presented with knowledge about global challenges, students can become frustrated and overwhelmed unless they also understand how they might contribute to solutions. Political science programs are uniquely positioned to provide students with the knowledge and skills necessary to become civically engaged members of the global community. However, we need to help students build bridges between knowledge and action. This can be accomplished by grounding global knowledge in concepts of citizenship. The evidence to support this claim can be found in student responses to the Atlas Program at Saint Louis University. This article describes the development and evolution of this program and analyzes its progress in fostering global civic engagement. By examining the evolution of the program, it highlights why it is necessary to root global knowledge in civic values. [Supple...
Isosurface smoothing using marching cubes and PN-triangles

We use PN-triangles to improve the quality of isosurfaces extracted by marching cubes. Our contribution is a pure-GPU solution for smoothed isosurfaces, combining GPU isosurface extraction with tessellation shaders for PN-triangles. The marching cubes algorithm was first introduced to reconstruct isosurfaces of implicit functions in a uniformly sampled space. Curved PN-triangles [Vlachos et al. 2001], or PN-triangles for short, is a fast way of generating smooth surfaces using limited local geometric information, such as per-vertex positions, and normals.
A new approach to anti-neutrino running in long-baseline neutrino oscillation experiments

We study the possibility to replace the anti-neutrino run of a long baseline neutrino oscillation experiment, with anti-neutrinos from muon decay at rest. The low energy of these neutrinos allows the use of inverse beta decay for detection in a Gadolinium-doped water Cerenkov detector. We show that this approach yields a factor of five times larger anti-neutrino event sample. The resulting discovery reaches in θ 13, the mass hierarchy and leptonic CP violation are compared with those from a conventional superbeam experiment with combined neutrino and anti-neutrino running. We find that this approach yields a greatly improved reach for CP violation and θ 13 while leaving the ability to measure the mass hierarchy intact.
Studies toward the synthesis of cinachyramine. An efficient route to 1,5-diazabicyclo[4.4.0]dec-5-enes

Abstract Hydrogenation (3 atm) of readily available pyrido[1,2-a]pyrimidines 10, 14, and 17 over 5% Rh/Al2O3 forms 1,5-diazabicyclo[4.4.0]dec-5-enes 9, 15, and 18 in >95% yield, providing a general route to this little-studied class of compounds. All attempts to form the tetrahydro-1,2,4-triazine moiety of cinachyramine (1) by rearrangement of amidinium dimethylhydrazone 8 using the procedures developed by Kamatori to convert hydrazone 3a to tetrahydro-1,2,4-triazine 4a were unsuccessful.
Terahertz study of trichloroanisole by time-domain spectroscopy

Abstract The THz transmission spectra of three trichloroanisole (TCA) compounds (2,3,4-TCA, 2,4,6-TCA and 2,5,6-TCA) are measured using terahertz time-domain spectroscopy (THz-TDS). The spectrum of 2,4,6-TCA in the solid phase displays several discrete absorption peaks over frequency range from 0.1 to 1.5 THz, with significant peaks observed at 0.6, 0.95 and 1.2 THz. A weak absorption peak is observed near 0.2–0.3 THz. Computational chemistry using the B3LYP density functional method is used to study structure and internal rotations in 2,4,6-TCA, where results strongly suggest that frequencies of the CH3O–carbon(benzene) internal rotor of the methoxy group correspond to the observed spectra.
Solar oscillations observed in the total irradiance

The total solar irradiance measurements obtained by the active-cavity radiometer on board the Solar Maximum Mission have been analyzed for evidence of global oscillations. We find that the most energetic low-degree p-mode oscillations in the five-minute band have amplitudes of a few parts per million of the total irradiance, and we positively detect modes with l = 0, 1, and 2. The distribution in l differs from that of the velocity spectrum, with relatively more power at lower l values. The individual modes have narrow line widths, corresponding to values of Q greater than a few thousand, or lifetimes of at least a week. We do not detect the 160-min oscillation in the power spectrum, and place an upper limit of 5 parts per million (99.9% confidence) on its amplitude.
Energy harvesting under combined aerodynamic and base excitations

Abstract This paper investigates the transduction of a piezoaeroelastic energy harvester under the combination of vibratory base excitations and aerodynamic loadings. The harvester which consists of a rigid airfoil supported by nonlinear flexural and torsional springs is placed in an incompressible air flow and subjected to a harmonic base excitation in the plunge direction. Under this combined loading, the airfoil undergoes complex motions which strain a piezoelectric element producing a voltage across an electric load. To capture the qualitative behavior of the harvester, a five-dimensional lumped-parameter model which adopts nonlinear quasi-steady aerodynamics is used. A center manifold reduction is implemented to reduce the full model into one nonlinear first-order ordinary differential equation. The normal form of the reduced system is then derived to study slow modulation of the response amplitude and phase near the flutter instability. Below the flutter speed, the response of the harvester is observed to be always periodic with the air flow serving to amplify the influence of the base excitation on the response by reducing the effective stiffness of the system, and hence, increasing the RMS output power. Beyond the flutter speed, two distinct regions are observed. The first occurs when the base excitation is small and/or when the excitation frequency is not close to the frequency of the self-sustained oscillations induced by the flutter instability. In this case, the response of the harvester is two-period quasiperiodic with amplitude modulation due to the presence of two incommensurate frequencies in the response. This amplitude modulation reduces the RMS output power. In the second region, the amplitude of excitation is large enough to eliminate the quasiperiodic response by causing the two frequencies to lock into each other. In this region, the response becomes periodic and the output power increases exhibiting little dependence on the base excitation.
Sensitive limits on the water abundance in cold low-mass molecular cores

We present Submillimeter Wave Astronomy Satellite observations of water vapor in two cold starless clouds, B68 and core D in ρ Ophiuchi. Sensitive nondetections of the 110-101 transition of o-H2O are reported for each source. Both molecular cores have been previously examined by detailed observations that have characterized the physical structure. Using these rather well-defined physical properties and a Monte Carlo radiation transfer model, we have removed one of the largest uncertainties from the abundance calculation and set the lowest water abundance limit to date in cold low-mass molecular cores. These limits are x(o-H2O) < 3 × 10-8 (relative to H2) and x(o-H2O) < 8 × 10-9 in B68 and ρ Oph D, respectively. Such low abundances confirm the general lack of ortho-water vapor in cold (T < 20 K) cores. Provided that the ortho/para ratio of water is not near zero, these limits are well below theoretical predictions and appear to support the suggestion that most of the water in dense low-mass cores is frozen onto the surfaces of cold dust grains.
Delayed X-ray emission from fallback in compact-object mergers

When double neutron star or neutron star–black hole binaries merge, the final remnant may comprise a central solar-mass black hole surrounded by a ∼0.01–0.1 M⊙ torus. The subsequent evolution of this disc may be responsible for short γ-ray bursts (SGRBs). A comparable amount of mass is ejected into eccentric orbits and will eventually fallback to the merger site after ∼0.01 s. In this paper, we investigate analytically the fate of the fallback matter, which may provide a luminous signal long after the disc is exhausted. We find that matter in the eccentric tail returns at a super-Eddington rate and eventually (≳0.1 s) is unable to cool via neutrino emission and accrete all the way to the black hole. Therefore, contrary to previous claims, our analysis suggests that fallback matter is not an efficient source of late-time accretion power and unlikely to cause the late-flaring activity observed in SGRB afterglows. The fallback matter rather forms a radiation-driven wind or a bound atmosphere. In both the cases, the emitting plasma is very opaque and photons are released with a degraded energy in the X-ray band. We therefore suggest that compact binary mergers could be followed by an ‘X-ray renaissance’, as late as several days to weeks after the merger. This might be observed by the next generation of X-ray detectors.
Change or Decay? An interpretation of late Holocene archaeological evidence from the Hamersley Plateau, Western Australia

Data collected from the Hamersley Plateau over the last four decades are examined for patterns in the archaeological record. Data relating to the timing of the archaeological appearance of backed artefacts, seed-grinding technology and rock art are currently too few to indicate major cultural changes with certainty. Increases in numbers of radiocarbon dates from archaeological sites on the Hamersley Plateau are evident in the late Holocene. This can be interpreted as a pattern of cultural change or natural decay in datable material. I conclude that taphonomic bias is the most important variable in the distribution of the radiocarbon date sample from the Hamersley Plateau. That said, further accumulation of dates and data may show archaeological changes in the Hamersley Plateau that represent local expressions of broader trends in the Australian semi-arid and arid zones.
Multicomponent spray computations in a modified centerbody combustor

The flow properties of the near-wake region of a ducted, bluff-body combustor are presented, based upon finite-difference computations involving turbulent, reacting flows with polydisperse and multicomponent sprays. The analysis advances the state-of-the-art for the representation of the liquid-phase and for the coupling between the phases. The gas phase representation is existing state-of-the-art. Both droplet vaporization and turbulent mixing rates are found to be rate-controlling in the primary reaction region, and the mixing rate is identified to be the rate-controlling process in the later stages of combustion. Under the inflow conditions leading to an equivalence ratio of one based on the primary air/fuel mass flow rates, the primary reaction region is found to be fuel-rich. Enhanced energy conversion is observed to result from improved mixing; the effects of fuel composition are found to be negligible. Near the wake-extinction limit of the combustor the effects of fuel composition are found to be very significant.
African Women in the Entrepreneurial Landscape: Reconsidering the Formal and Informal Sectors

Informal and formal sectors can be seen as “dual economies” of African countries. This article discusses the entrepreneurial landscape in Africa considering both sectors, as well as the continuum from small to large within each. It queries whether there can be mobility within and between sectors and whether upward movement, as seen elsewhere, is possible for most African entrepreneurs. The landscape displays the range of women entrepreneurs from traditional microenterprises to large informal-sector traders, from small- to large-scale formal-sector companies, as well as emerging globalists (the “new generation of African entrepreneurs”). Paradigms compare and contrast these entrepreneurs in terms of demographic variables, types of typical enterprises and companies, product sources and markets, start-up capital, networks and associations, and mobility within and between the sectors. Findings show the informal−formal distinction is useful to disentangle the landscape, but that movement between informal secto...
The Concept of a Stare‐Mode Astrometric Space Mission

Abstract : In this paper, we introduce the concept of a stare-mode astrometric space mission. The traditionally accepted mode of operation for a mapping astrometric space mission is that of a continuously scanning satellite, such as the successful Hipparcos and planned Gaia missions. With the advent of astrometry missions mapping out stars to 20th magnitude, the stare mode has become competitive. A stare mode of operation has several advantages over a scanning mission if absolute parallax and throughput issues can be successfully addressed. Requirements for a stare-mode operation are outlined here. The mission precision for a stare-mode astrometric mission is derived as a function of instrumental parameters, and examples are given. The stare-mode concept has been accepted as a baseline for the NASA road map study of the Origins Billions Star Survey (OBSS) mission and the proposed Milliarcsecond Pathfinder Survey (MAPS) microsatellite project.
Palmyrolide A, an Unusually Stabilized Neuroactive Macrolide from Palmyra Atoll Cyanobacteria

Palmyrolide A (1) is a new neuroactive macrolide isolated from a marine cyanobacterial assemblage composed of Leptolyngbya cf. and Oscillatoria spp. collected from Palmyra Atoll. It features a rare N-methyl enamide and an intriguing t-butyl branch; the latter renders the adjacent lactone ester bond resistant to hydrolysis. Consistent with its significant suppression of calcium influx in cerebrocortical neurons (IC50 = 3.70 μM), palmyrolide A (1) showed a relatively potent sodium channel blocking activity in neuro-2a cells (IC50 = 5.2 μM), without appreciable cytotoxicity.
Theory and Experiment in Gravitational Physics

New technological advances have made it feasible to conduct measurements with precision levels which are suitable for experimental tests of the theory of general relativity. This book has been designed to fill a new need for a complete treatment of techniques for analyzing gravitation theory and experience. The Einstein equivalence principle and the foundations of gravitation theory are considered, taking into account the Dicke framework, basic criteria for the viability of a gravitation theory, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973). Gravitation as a geometric phenomenon is considered along with the parametrized post-Newtonian formalism, the classical tests, tests of the strong equivalence principle, gravitational radiation as a tool for testing relativistic gravity, the binary pulsar, and cosmological tests.
Burning Aluminum Particles Inside a Laboratory-Scale Solid Rocket Motor

Single and agglomerated aluminum droplets were studied in a solid rocket motor test chamber with optical access to the internal flow at 6-22 atm and 2300 K. The chamber was pressurized by burning a main grain ammonium perchlorate/hydroxyl-terminated poly-butadiene propellant, and the burning aluminum droplets were generated by a smaller aluminized solid propellant sample, center mounted in the flow. A 35-mm camera was used with a chopper wheel to give droplet flame diameter vs time measurements of the burning droplets in flight, from which burning rate laws were developed. A high-speed video charge-coupled device with high-magnification optics imaged the flame/smoke cloud surrounding the burning liquid droplets. The intensity profiles of the droplet images were deconvoluted using an Abel inversion to give true intensity profiles. Both single and agglomerated droplets were studied, where agglomerates comprise hundreds of parent particles or more. The Abel inversions show that the relative smoke cloud size is not constant with diameter, but instead grows as the droplet shrinks, by ∼D - 0 . 5 , for both the single and agglomerated droplets. Measured diameter trajectories show that, for single droplets, the mean diameter law is D 0 . 7 5 = D 0 . 7 5 0 - 8.t, and, for agglomerated droplets, D 1 . 0 = D 1 . 0 0 - 20.t. For both single and agglomerated droplets, the burning rate slope k did not change significantly for the chamber pressure range studied.
Determination of Free Carbon in Cured Rubber Stocks

Abstract A method for the determination of free carbon in vulcanized rubber stocks is described. The sample is softened in boiling p-dichlorobenzene before treatment with tert-butyl hydroperoxide in the presence of osmium tetroxide. No difficulties are encountered in the filtration of the carbon black. The carbon black is washed on the filter with dilute nitric acid to remove acid-soluble inorganic fillers. The method has been successfully applied to natural rubber, GR-S, Butyl rubber, and Neoprene. No correction is necessary.
Active Control of Cryogenic Propellants in Space

A new era of space exploration is being planned. Exploration architectures under consideration require the long term storage of cryogenic propellants in space. This requires development of active control systems to mitigate the effect of heat leak. This work summarizes current state of the art, proposes operational design strategies and presents options for future architectures. Scaling and integration of active systems will be estimated. Ideal long range spacecraft systems will be proposed with exploration architecture benefits considered.
Poisoned feedback: The impact of malicious users in closed-loop multiuser mimo systems

Accurate channel state information (CSI) at the transmitter is critical for maximizing spectral efficiency on the downlink of multi-antenna networks. In this work we analyze a novel form of physical layer attacks on such closed-loop wireless networks. Specifically, this paper considers the impact of deliberately inaccurate feedback by malicious users in a multiuser multicast system. Numerical results demonstrate the significant degradation in performance of closed-loop transmission schemes due to intentional feedback of false CSI by adversarial users.
Nonparametric Inference for the Cosmic Microwave Background

The cosmic microwave background (CMB), which permeates the entire Universe, is the radiation left over from just 380,000 years after the Big Bang. On very large scales, the CMB radiation field is smooth and isotropic, but the existence of structure in the Universe—stars, galaxies, clusters of galaxies, …—suggests that the field should fluctuate on smaller scales. Recent observations, from the Cosmic Microwave Background Explorer to the Wilkinson Microwave Anisotropy Probe, have strikingly confirmed this prediction. CMB fluctuations provide clues to the Universe’s structure and composition shortly after the Big Bang that are critical for testing cosmological models. For example, CMB data can be used to determine what portion of the Universe is composed of ordinary matter versus the mysterious dark matter and dark energy. To this end, cosmologists usually summarize the fluctuations by the power spectrum, which gives the variance as a function of angular frequency. The spectrum’s shape, and in particular the location and height of its peaks, relates directly to the parameters in the cosmological models. Thus, a critical statistical question is how accurately can these peaks be estimated. We use recently developed techniques to construct a nonparametric confidence set for the unknown CMB spectrum. Our estimated spectrum, based on minimal assumptions, closely matches the model-based estimates used by cosmologists, but we can make a wide range of additional inferences. We apply these techniques to test various models and to extract confidence intervals on cosmological parameters of interest. Our analysis shows that, even without parametric assumptions, the first peak is resolved accurately with current data but that the second and third peaks are not.
On values and phenomenology

Abstract This article considers the drivers of professional happiness among academic consumer psychologists, and presents a model of the recursive dynamics of favorable and unfavorable professional phenomenology, which was developed based on a series of depth interviews with a diverse set of respondents. Core professional values typically shared by consumer psychologists are discussed, as are the roadblocks that cause disconnects between individuals' values and their professional experiences. The paper additionally discusses ubiquitous experiential traps that powerfully undermine professional happiness, and concludes with prescriptive advice for creating departments that facilitate the productivity and well-being of constituent faculty.
Quantal synaptic failures improve performance in a sequence learning model of hippocampal CA3

Abstract Quantal synaptic failures are random, independent events in which the arrival of an action potential fails to release transmitter. Although quantal failures destroy information, there exist conditions where such failures enhance learning by a neural network model of the hippocampus. In particular, we show how the appropriate failure rate can allow the model to learn the hippocampally dependent task of transverse patterning. Usefully, since lowered activity levels produce higher memory capacity, synaptic failures lead to robust performance at lowered activity levels. Thus, the synaptic failure mechanism is another example of a random fluctuation that improves neural network computations.
Wannier center sheets in topological insulators

We argue that various kinds of topological insulators (TIs) can be insightfully characterized by an inspection of the charge centers of the hybrid Wannier functions, defined as the orbitals obtained by carrying out a Wannier transform on the Bloch functions in one dimension while leaving them Bloch-like in the other two. From this procedure, one can obtain the Wannier charge centers (WCCs) and plot them in the two-dimensional projected Brillouin zone. We show that these WCC sheets contain the same kind of topological information as is carried in the surface energy bands, with the crucial advantage that the topological properties of the bulk can be deduced from bulk calculations alone. The distinct topological behaviors of these WCC sheets in trivial, Chern, weak, strong, and crystalline TIs are first illustrated by calculating them for simple tight-binding models. We then present the results of first-principles calculations of the WCC sheets in the trivial insulator ${\mathrm{Sb}}_{2}$Se${}_{3}$, the weak TI KHgSb, and the strong TI ${\mathrm{Bi}}_{2}$Se${}_{3}$, confirming the ability of this approach to distinguish between different topological behaviors in an advantageous way.