cssi/SciSciGPT-SciSciNet huggingface dataset:
Utilization of Monte Carlo Calculations in Radiation Transport Analyses to Support the Design of the U.S. Spallation Neutron Source (SNS)

The Department of Energy (DOE) has given the Spallation Neutron Source (SNS) project approval to begin Title I design of the proposed facility to be built at Oak Ridge National Laboratory (ORNL) and construction is scheduled to commence in FY01. The SNS initially will consist of an accelerator system capable of delivering an approximately 0.5 microsecond pulse of 1 GeV protons, at a 60 Hz frequency, with 1 MW of beam power, into a single target station. The SNS will eventually be upgraded to a 2 MW facility with two target stations (a 60 Hz station and a 10 Hz station). The radiation transport analysis, which includes the neutronic, shielding, activation, and safety analyses, is critical to the design of an intense high-energy accelerator facility like the proposed SNS, and the Monte Carlo method is the cornerstone of the radiation transport analyses.
Copper Catalyzed Azide‐Alkyne Cycloadditions on Solid Surfaces: Applications and Future Directions

The Copper Catalyzed Azide-Alkyne Cycloaddition (CuAAC), a paradigm of “click” chemistry has found numerous applications in the field of surface chemistry. This minireview discusses the reaction from a surface chemist's perspective. Specific advantages, limitations, and surface related concerns are discussed. We review the types of solid surfaces that have been modified via click chemistry and conclude with several elegant applications.
Differences between pickup truck and automobile driver-owners

This study compares pickup truck driver-owners and drivers who owned only automobiles with respect to demographic factors, conditions of use, risk-taking driving behavior, prior driving history and attitudes towards motor vehicle laws. A telephone survey conducted in Riverside County, CA determined that 36% of the households had a pickup truck. Pickup truck owners were primarily male, aged 30-39 years, married, reported lower restraint use and more risky driving behaviors, and had more traffic citations. Differences in behaviors and attitudes were largely a function of age and gender. There is a need to design appropriate occupant safety interventions for those most likely to own pickup trucks.
On the Tutte-Krushkal-Renardy polynomial for cell complexes

Recently V. Krushkal and D. Renardy generalized the Tutte polynomial from graphs to cell complexes. We show that evaluating this polynomial at the origin gives the number of cellular spanning trees in the sense of A. Duval, C. Klivans, and J. Martin. Moreover, after a slight modification, the Tutte-Krushkal-Renardy polynomial evaluated at the origin gives a weighted count of cellular spanning trees, and therefore its free term can be calculated by the cellular matrix-tree theorem of Duval et al. In the case of cell decompositions of a sphere, this modified polynomial satisfies the same duality identity as the original polynomial. We find that evaluating the Tutte-Krushkal-Renardy along a certain line gives the Bott polynomial. Finally we prove skein relations for the Tutte-Krushkal-Renardy polynomial.
Iterative decoding and turbo equalization: The Z-crease phenomenon

Iterative probabilistic inference, popularly dubbed the soft-iterative paradigm, has found great use in a wide range of communication applications, including turbo decoding and turbo equalization. The classic approach of analyzing the iterative approach inevitably use the statistical and information-theoretical tools that bear ensemble-average flavors. This paper consider the per-block error rate performance, and analyzes it using nonlinear dynamical theory. By modeling the iterative processor as a nonlinear dynamical system, we report a universal “Z-crease phenomenon:” the zig-zag or up-and-down fluctuation - rather than the monotonic decrease - of the per-block errors, as the number of iteration increases. Using the turbo decoder as an example, we also report several interesting motion phenomenons which were not previously reported, and which appear to correspond well with the notion of “pseudo codewords” and “stopping/trapping sets.” We further propose a heuristic stopping criterion to control Z-crease and identify the best iteration. Our stopping criterion is most useful for controlling the worst-case per-block errors, and helps to significantly reduce the average-iteration numbers.
Rejection of the binary broad-line region interpretation of double-peaked emission lines in three active galactic nuclei

It has been suggested that the peculiar double-peaked Balmer lines of certain broad-line radio galaxies come from individual broad-line regions associated with the black holes of a supermassive binary. We continue to search for evidence of the radial velocity variations characteristics of a double-lined spectroscopic binary that are required in such a model. After spectroscopic monitoring of three suitable candidates (Arp 102B, 3C 390.3, and 3C 332) spanning two decades, we find no such long-term systematic changes in radial velocity. A trend noticed by Gaskell in one of the Balmer-line peaks of 3C 390.3 before 1988 did not continue after that year, invalidating his inferred orbital period and mass. Instead, we find lower limits on the plausible orbital periods that would require the assumed supermassive binaries in all three objects to have total masses in excess of 1010 M☉. In the case of 3C 390.3, the total binary mass must exceed 1011 M☉ to satisfy additional observational constraints on the inclination angle. We argue that such large binary black hole masses are difficult to reconcile with other observations and with theory. In addition, there are peculiar properties of the line profiles and flux ratios in these objects that are not explained by ordinary broad-line region cloud models. We therefore doubt that the double-peaked line profiles of Arp 102B, 3C 390.3, and 3C 332 arise in pairs of broad-line regions. Rather, they are much more likely to be intimately associated with single black holes. The recent discoveries of transient but otherwise similar double-peaked emission lines in nearby active galactic nuclei bolster the view that double-peaked emission lines are commonly produced by a single compact source.
The heat capacities of titanium silicides Ti5Si3, TiSi and TiSi2

Abstract Titanium silicides Ti 5 Si 3 , TiSi and TiSi 2 have been prepared and characterized by X-ray powder diffraction and optical metallography. The heat capacities of the silicides have been measured by means of differential scanning calorimetry (DSC) in the temperature range of 230 to 600 K. The heat capacities of Ti 5 Si 3 , TiSi and TiSi 2 at 298 K have been found to be 181±3, 47.2±0.6 and 66.6±0.9 J mol −1 K, respectively. The obtained results are compared with literature heat capacity data.
Statistical Hydrodynamics in Porous Media

The statistics of disordered phenomena as exemplified by Einstein's theory of the Brownian motion is applied to the flow of fluids through porous media.It is shown that such a statistical treatment of the hydrodynamics in porous media automatically explains some well‐known phenomena in a more satisfactory manner than do capillaric models. The statistical theory leads to a differential equation of motion of the fluid which is a modification of that of Darcy; notably a new macroscopic quantity is introduced which is termed ``dispersivity.'' This quantity is indicative of the sideways dispersion which a stream of fluid undergoes when it is passing through the porous medium. Under certain statistical assumptions outlined in the paper, the dispersivity becomes a constant of the porous medium.The new differential equation of motion of the fluid is discussed in detail and some indications about applications are given.
Stock positioning and performance estimation for distribution systems with service constraints

The problem of minimizing average inventory costs in a distribution system consisting of one warehouse and multiple retailers subject to fill rate service constraints is studied. An effective algorithm to evaluate the optimal base-stock policy and cost under local control is provided. Properties of the optimal base-stock levels at each location are established. In addition, heuristics and closed-form approximations that yield insights into the drivers of system performance are also provided. An extensive numerical study to gain insight into the optimal solution, stock positioning and when to use the heuristics and approximations is presented. An example of how logistics postponement and fill-rate constraints affect the distribution system's performance is quantified. A discussion on how to study and allocate stocks across an arborescence system with more than two echelons is presented.
Michael Additions of Highly Basic Enolates to ortho-Quinone Methides

A protocol by which ketone or ester enolates and ortho-quinone methides (o-QMs) are generated in situ in a single reaction flask from silylated precursors under the action of anhydrous fluoride is reported. The reaction partners are joined to give a variety of β-(2-hydroxyphenyl)-carbonyl compounds in 32–94% yield in a single laboratory operation. The intermediacy of o-QMs is supported by control experiments utilizing enolate precursors and conventional alkyl halides as competitive alkylating agents and the isolation of 1,5-dicarbonyl products resulting from conjugate additions that do not restore the aromatic system.
Substrate-controlled diastereoselectivity in catalyzed and uncatalyzed hydroborations of allylic amine derivatives

Abstract Hydroboration of the protected, homochiral allylic amines (6)–(10) with 9-BBN, and with catecholborane/rhodium catalyst, give different stereoselectivities; the catalyzed reactions provide access to syn -3-amino-2-methyl alcohols (11)–(15) .
Airborne vector gravimetry using precise, position-aided inertial measurement units

Vector gravimetry using a precise inertial navigation system continually updated with external position data, for example using GPS, is studied with respect to two problems. The first concerns the attitude accuracy requirement for horizontal gravity component estimation. With covariance analyses in the space and frequency domains it is argued that with relatively stable uncompensated gyro drift, the short-wavelength gravity vector can be estimated without the aid of external attitude updates. The second problem concerns the state-space estimation of the gravity signal where considerable approximations must be assumed in the gravity model in order to take advantage of the ensemble error estimation afforded by the Kalman filter technique. Gauss-Markov models for the gravity field are specially designed to reflect the attenuation of the signal at a specific altitude and the omission of the long-wavelength components from the estimation. With medium accuracy INS/GPS systems, the horizontal components of gravity with wavelengths shorter than 250 km should be estimable to an accuracy of 4–6 mgal (µg); while high accuracy systems should yield an improvement to 1–2 mgal.
The Abundances of Light Neutron-Capture Elements in Planetary Nebulae. I. Photoionization Modeling and Ionization Corrections*

We have conducted a large-scale survey of 120 planetary nebulae (PNe) to search for the near-infrared emission lines [Kr III] 2.199 μm and [Se IV] 2.287 μm. The neutron (n)-capture elements Se and Kr may be enriched in a PN if its progenitor star experienced s-process nucleosynthesis and third dredge-up. In order to determine Se and Kr abundances, we have added these elements to the atomic databases of the photoionization codes Cloudy and XSTAR, which we use to derive ionization correction factors (ICFs) to account for the abundances of unobserved Se and Kr ions. However, much of the atomic data governing the ionization balance of these two elements are unknown, and have been approximated from general principles. We find that uncertainties in the atomic data can lead to errors approaching 0.3 dex in the derived Se abundances and up to 0.2-0.25 dex for Kr. To reduce the uncertainties in the Kr ionization balance stemming from the approximate atomic data, we have modeled 10 bright PNe in our sample, selected because they exhibit emission lines from multiple Kr ions in their optical and near-infrared spectra. We have empirically adjusted the uncertain Kr atomic data until the observed line intensities of the various Kr ions are adequately reproduced by our models. Using the adjusted Kr atomic data, we have computed a grid of models over a wide range of physical parameters (central star temperature, nebular density, and ionization parameter) and derived formulae that can be used to compute Se and Kr ICFs. In the second paper of this series, we will apply these ICFs to our full sample of 120 PNe, which comprises the first large-scale survey of n-capture elements in PNe.
Bimetallic catalysis in the highly enantioselective ring–opening reactions of aziridines

Bimetallic yttrium- and lanthanide-salen complexes, readily prepared from commercially available metal isopropoxides, 2-dimethylaminoethanol, 1,1′-binaphthyl-2,2′-diamine and 2-hydroxy-3-methoxybenzaldehyde (3 steps) catalyze highly enantioselective ring opening (∼90–99% ee) reactions of meso-N-4-nitrobenzoyl aziridines by TMSCN and TMSN3. The TMSN3-mediated reactions give the highest enantioselectivities reported to date for several prototypical aziridines. Selectivity in a related ring opening by silyl isothiocyanates depends on the substituents on silicon, larger tBuPh2SiNCS giving the best selectivities, especially when an yttrium or ytterbium complex is used as the catalyst. The bimetallic yttrium complex also effects unprecedented regiodivergent parallel kinetic resolution of racemic monosubstitued aziridines upon reaction with TMSN3. In these reactions, each of the enantiomers undergoes nucleophilic addition of azide at different carbons giving two products in nearly enantiomerically pure form. To explain the dramatic differences in the selectivities between the mono- and bimetallic catalysts in these reactions, a mechanism that involves activation of both the electrophile (aziridine) and the nucleophile (azide or cyanide) at two different metals of the bimetallic complex is proposed. Molecular weight determination by vapor pressure osmometry, diffusion ordered NMR spectroscopy (DOSY) and kinetic studies, which suggest first order dependence on the concentration of the catalyst, provide strong support for this proposal.
The ionization fraction of Barnard 68: Implications for star and planet formation

We present a detailed study of the ionization fraction of the Barnard 68 prestellar core, using millimeter H13CO+ and DCO+ lines observations. These observations are compared to the predictions of a radiative transfer model coupled to a chemical network that includes depletion on grains and gas-phase deuterium fractionation. Together with previous observations and modeling of CO and isotopologues, our H 13CO+ and DCO+ observations and modeling allow us to place constraints on the metal abundance and the cosmic ionization rate. The H13CO+ emission is well reproduced for metal abundances lower than 3 × 10-9 and a standard cosmic-ray ionization rate. However, the observations are also consistent with a complete depletion of metals, i.e., with cosmic rays as the only source of ionization at visual extinctions greater than a few AV. The DCO+ emission is found to be dependent of the ortho-to-para H2 ratio and indicates a ratio of ~10 -2. The derived ionization fraction is about 5 × 10-9 with respect to H nuclei, which is about an order of magnitude lower than that observed in the L1544 core. The corresponding ambipolar diffusion timescale is found to be an order of magnitude larger than the free fall timescale at the center of the core. The inferred metal abundance suggests that magnetically inactive regions (dead zones) are present in protostellar disks.
A highly efficient three-component coupling of aldehyde, alkyne, and amines via C-H activation catalyzed by gold in water

A highly efficient three-component-coupling of aldehyde, alkyne, and amine (A3 Coupling) catalyzed by gold via C−H activation was developed in water. The reaction is general, and nearly quantitative yields of the corresponding propargylamines were obtained in most cases. Both aromatic and aliphatic aldehydes and amines can be used for the reaction. No additional cocatalyst or activator is required. A mechanistic rationale for the reaction has been proposed.
Deterministic collision free communication despite continuous motion

We present a deterministic solution for nodes in a mobile wireless ad hoc network to communicate reliably and maintain local neighborhood information. The nodes are located on a two-dimensional plane and may be in continuous motion. In our solution we tile the plane with hexagons. Each hexagon is assigned a color from a finite set of colors. Two hexagons of the same color are located sufficiently far apart so that nodes in these two hexagons cannot interfere with each other's broadcasts. Based on this partitioning we develop a periodic deterministic schedule for mobile nodes to broadcast. This schedule guarantees collision avoidance. Broadcast slots are tied to geographic locations instead of nodes and the schedule for a node changes dynamically as it moves from tile to tile. The schedule allows nodes to maintain information about their local neighborhood. This information in turn is used to keep the schedule collision-free. We demonstrate the correctness of our algorithm, and discuss how the periodic schedule can be adapted for different scenarios. The periodic schedule, however, does not address the problem of initial neighbor discovery at start-up. We give a separate algorithm for this problem of initially discovering nodes present within communication range at start-up.
4-amino-3-(2,3,5-tri-O-benzyl-β-d-ribofuranosyl)-5-pyrazolecarbonitrile. Synthesis and conversion into a sugar-blocked 5,7-disubstituted formycin analog

Abstract The title compound, a potential intermediate to protected C -nucleoside analogs related to formycin A, was synthesized via a new route wherein 2,3,5-tri- O -benzyl-1- O - p -nitrophenyl)- d -ribofuranose was converted to 2,5-anhydro-3,4,6-tri- O -benzyl- d -allonic acid, and further transformed into 4-( tert -butyloxycarbonyl)-5-ethoxycarbonyl-3-(2,3,5-tri- O -benzyl-β- d -ribofuranosyl)pyrazole. After amidation and dehydration to form the 4-( tert -butyloxycarbonyl)-5-pyrazolecarbonitrile, acidolysis followed by a Curtius-type sequence afforded the 4-amino-5-pyrazolecarbonitrile nucleoside. Treatment of the latter with nitrous acid and copper chloride in a Sandmeyer-type reaction gave a diazonitrile rather than a chloronitrile. Attempts to convert either the aminonitrile or the diazonitrile to 5,7-diamino-3-(2,3,5-tri- O -benzyl-β- d -ribofuranosyl)pyrazolo[4,3- d ] pyrimidine (5-aminoformycin A) by condensation with guanidine or N,N -dimethylguanidine were unsuccessful. Condensation of the aminonitrile with carbon disulfide in pyridine provided access to the formycin system in the form of 3-(2,3,5-tri- O -benzyl-β- d -ribofuranosyl)pyrazolo[4,3- d ]pyrimidine-5,7-dithione.
The Carriers of the Interstellar Unidentified Infrared Emission Features: Aromatic or Aliphatic?

The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m, commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules, have been recently ascribed to coal- or kerogen-like organic nanoparticles with a mixed aromatic-aliphatic structure. However, we show in this Letter that this hypothesis is inconsistent with observations. We estimate the aliphatic fraction of the UIE carriers based on the observed intensities of the 3.4 {mu}m and 6.85 {mu}m emission features by attributing them exclusively to aliphatic C-H stretch and aliphatic C-H deformation vibrational modes, respectively. We derive the fraction of carbon atoms in aliphatic form to be <15%. We conclude that the UIE emitters are predominantly aromatic, with aliphatic material at most a minor part of the UIE carriers. The PAH model is consistent with astronomical observations and PAHs dominate the strong UIE bands.
ANALYSIS AND DESIGN OF NUMERICAL SCHEMES FOR GAS DYNAMICS, 2: ARTIFICIAL DIFFUSION AND DISCRETE SHOCK STRUCTURE

The effect of artificial diffusion on discrete shock structures is examined for a family of schemes which includes scalar diffusion, convective upwind and split pressure (CUSP) schemes, and upwind schemes with characteristics splitting. The analysis leads to conditions on the diffusive flux such that stationary discrete shocks can contain a single interior point. The simplest formulation which meets these conditions is a CUSP scheme in which the coefficients of the pressure differences is fully determined by the coefficient of convective diffusion. It is also shown how both the characteristic and CUSP schemes can be modified to preserve constant stagnation enthalpy in steady flow, leading to four variants, the E and H-characteristic schemes, and the E and H-CUSP schemes. Numerical results are presented which confirm the properties of these schemes.
Estimation of maneuvering aircraft states and time-varying wind with turbulence

Abstract This paper presents an application of the Square Root-Unscented Kalman Filter (SR-UKF) to the estimation of aircraft system states and to the estimation of the total wind vector made up of a time-varying prevailing wind plus turbulence. The estimates are computed using conventional auto-pilot sensors with exponentially correlated measurement errors. The objective of this work is to investigate the convergence limitations of the estimates considering the covariance and correlation time constants of the measurement error models as well as the level of intensity of the turbulence.
Simultaneous multi-isotope trapping of ytterbium

Working with ytterbium ~Yb!, we demonstrate dual-isotope magneto-optic traps of extreme experimental simplicity yet containing either fermion-boson or boson-boson isotope pairs. Pairs studied include Yb1Yb ~a fermion-boson mixture! and Yb1Yb and Yb1Yb ~boson-boson mixtures!. Trapping is performed using the Yb (6s)S0-(6s6p) P1 transition, an uncooled thermal source, and bichromatic trapping beams. Static and dynamic properties of the composite cloud are conveniently probed on the spinforbidden (6s)S0-(6s6p) P1 transition. A unique strategy for continuously loading these samples into magnetic traps is described.
Performability evaluation of CSMA/CD and CSMA/DCR protocols under transient fault conditions

This study compares the performability of the carrier sense multiple access protocol with collision detection (CSMA/CD) and a variant, the CSMA protocol with deterministic CD ( CSMA/DCR), which uses a deterministic collision-resolution, considering errors induced by transient faults. The long-term effect that transient faults can induce on the electronics which implement the protocols is considered. This is done using stochastic activity networks (SANs), a stochastic extension of Petri nets. SANs permits the detailed workings of CSMA/DCR and traditional CSMA/CD to be represented accurately, as well as the effects of transient faults. >
Parallel Hierarchical Affinity Propagation with MapReduce

The accelerated evolution and explosion of the Internet and social media is generating voluminous quantities of data (on zettabyte scales). Paramount amongst the desires to manipulate and extract actionable intelligence from vast big data volumes is the need for scalable, performance-conscious analytics algorithms. To directly address this need, we propose a novel MapReduce implementation of the exemplar-based clustering algorithm known as Affinity Propagation. Our parallelization strategy extends to the multilevel Hierarchical Affinity Propagation algorithm and enables tiered aggregation of unstructured data with minimal free parameters, in principle requiring only a similarity measure between data points. We detail the linear run-time complexity of our approach, overcoming the limiting quadratic complexity of the original algorithm. Experimental validation of our clustering methodology on a variety of synthetic and real data sets (e.g. images and point data) demonstrates our competitiveness against other state-of-the-art MapReduce clustering techniques.
On Optimal Language Compression for Sets in PSPACE/poly

We show that if DTIME[2 O(n)] is not included in DSPACE[2 o(n)], then, for every set B in PSPACE/poly, all strings x in B of length n can be represented by a string compressed(x) of length at most log(|B =n |)+O(log n), such that a polynomial-time algorithm, given compressed(x), can distinguish x from all the other strings in B =n . Modulo the O(log n) additive term, this achieves the information-theoretic optimum for string compression. We also observe that optimal compression is not possible for sets more complex than PSPACE/poly because for any time-constructible superpolynomial function t, there is a set A computable in space t(n) such that at least one string x of length n requires compressed(x) to be of length 2 log(|A =n |).
Analysis of a campus-wide wireless network

Understanding usage patterns in wireless local-area networks (WLANs) is critical for those who develop, deploy, and manage WLAN technology, as well as those who develop systems and application software for wireless networks. This paper presents results from the largest and most comprehensive trace of network activity in a large, production wireless LAN. For eleven weeks we traced the activity of nearly two thousand users drawn from a general campus population, using a campus-wide network of 476 access points spread over 161 buildings at Dartmouth College. Our study expands on those done by Tang and Baker, with a significantly larger and broader population.We found that residential traffic dominated all other traffic, particularly in residences populated by newer students; students are increasingly choosing a wireless laptop as their primary computer. Although web protocols were the single largest component of traffic volume, network backup and file sharing contributed an unexpectedly large amount to the traffic. Although there was some roaming within a network session, we were surprised by the number of situations in which cards roamed excessively, unable to settle on one access point. Cross-subnet roams were an especial problem, because they broke IP connections, indicating the need for solutions that avoid or accommodate such roams.
Alternative Approach to 1,2,4-Triazole-3-carboxamides

The conversion of trichloromethyl and tribromomethyltriazoles to the corresponding carboxamide derivatives is described. The trihalomethyl analogs are straightforward to make and react readily with a range of amines to produce carboxamides. The strategy avoids the problems of decarboxylation associated with the use of triazole acids.
Seismic attenuation due to patchy saturation

[1] In porous rocks saturated in patches by two immiscible fluids, seismic compression causes the fluid with the larger bulk modulus to respond with a larger change in fluid pressure than the fluid with the smaller bulk modulus which results in fluid movement and seismic attenuation. For virtual rock samples having fluid distributions obtained using the invasion percolation model, attenuation is determined using finite difference numerical experiments based on the laws of poroelasticity. Analytical models are also proposed to explain the numerical results. When oil invades water, the equilibration is controlled by the geometry of the invading oil which has a narrow range of small diffusion lengths resulting in a single relaxation frequency at high frequencies and not much seismic band attenuation. When water invades oil, the defending oil controls the equilibration, and a power law emerges for how attenuation varies with frequency due to the fractal nature of how saturation is varying with scale in the defending oil. For air invading water, the geometry of the defending water controls the equilibration, and a large amount of attenuation is observed over a wide range of frequencies including the seismic band due to the wide range in water patch sizes. However, when water invades air, the narrow fingers of invading water control the equilibration, and there is a single relaxation frequency at high frequencies that does not result in much seismic band attenuation.
VIVACE (Vortex Induced Vibration Aquatic Clean Energy): A New Concept in Generation of Clean and Renewable Energy From Fluid Flow

Any device aiming to harness the abundant clean and renewable energy from ocean and other water resources must have high energy density, be unobtrusive, have low maintenance, be robust, meet life cycle cost targets, and have a 10-20 year life. The vortex induced vibration aquatic clean energy (VIVACE) converter-invented by Bernitsas and Raghavan, patent pending through the University of Michigan-satisfies those criteria. It converts ocean/river current hydrokinetic energy to a usable form of energy such as electricity using VIV successfully and efficiently for the first time. VIVACE is based on the idea of maximizing rather than spoiling vortex shedding and exploiting rather than suppressing VIV. It introduces optimal damping for energy conversion while maintaining VIV over a broad range of vortex shedding synchronization. VIV occurs over very broad ranges of Reynolds (Re) number Only three transition regions suppress VIV. Thus, even from currents as slow as 0.25 m/s, VIVACE can extract energy with high power conversion ratio making ocean/river current energy a more accessible and economically viable resource. In this paper, the underlying concepts of the VIVACE converter are discussed. The designs of the physical model and laboratory prototype are presented. A mathematical model is developed, and design particulars for a wide range of application scales are calculated. Experimental measurements on the laboratory prototype are reported in the sequel paper and used here for preliminary benchmarking.
The software reliability game

The meaning of software reliability and the problems involved in attaining reliable software are examined from three perspectives: customer, producer, and user. The impact of reliable software on the public at large is discussed, emphasizing the importance of safeguarding the individual's right to privacy. Finally, the government's contribution to improving software quality is presented.
Quantitative Analysis of Hsp90-Client Interactions Reveals Principles of Substrate Recognition

HSP90 is a molecular chaperone that associates with numerous substrate proteins called clients. It plays many important roles in human biology and medicine, but determinants of client recognition by HSP90 have remained frustratingly elusive. We systematically and quantitatively surveyed most human kinases, transcription factors, and E3 ligases for interaction with HSP90 and its cochaperone CDC37. Unexpectedly, many more kinases than transcription factors bound HSP90. CDC37 interacted with kinases, but not with transcription factors or E3 ligases. HSP90::kinase interactions varied continuously over a 100-fold range and provided a platform to study client protein recognition. In wild-type clients, HSP90 did not bind particular sequence motifs, but rather associated with intrinsically unstable kinases. Stabilization of the kinase in either its active or inactive conformation with diverse small molecules decreased HSP90 association. Our results establish HSP90 client recognition as a combinatorial process: CDC37 provides recognition of the kinase family, whereas thermodynamic parameters determine client binding within the family.
A language for bitmap manipulation

In this paper we propose that bitmaps, or raster images, should be given full citizen status in the world of computer science. We introduce a calculus of bitmap operations and MUMBLE, a programming language appropriate for describing bitmap computations. We illustrate the use of MUMBLE by several interesting graphical applications. We also discuss the structure of BOP, an efficient implementation of the bitmap calculus that is the underpinning of our system.
Electroless deposition of soft magnetic CoNiP thin films

The ternary CoNiP soft magnetic films were deposited on silicon substrates by the autocatalytic electroless process. The deposition of these magnetic thin films was carried out by using different concentrations of cobalt (Co 2+ ), nickel (Ni 2+ ) and hypophosphite (H 2 PO - 2) ions in the bath, and by maintaining the bath at different pH levels. The composition and the magnetic characteristics of the deposited films were studied. The effects of varying the concentration of both metal ions and nonmetal ion (reducing agent) on the magnetic properties of the films were explored by increasing the concentration of precursor salts of Co 2+ ions from 0.002 to 0.008 M, Ni 2+ ions from 0.004 to 0.02 M, and H 2 PO - 2 ions from 0.02 to 0.25 M. The pH of the bath was varied in the range 7.0-9.0 in steps of 0.5. The magnetic moment and coercivity of the CoNiP films decreased when the concentrations of the metal ion was increased. However, when the pH was increased, the magnetic moment increased with a corresponding reduction in the coercivity values. Maintaining the bath pH within a narrow range of 8.5 to 9.0 was found to be critical for the formation of high quality soft-magnetic films which exhibit large magnetic moments and low coercivity.
Modified-scaled hierarchical equation of motion approach for the study of quantum coherence in photosynthetic complexes

We present a detailed theoretical study of the transfer of electronic excitation energy through the Fenna-Matthews-Olson (FMO) pigment-protein complex, using the new developed modified scaled hierarchical approach [Shi Q. et al, J Chem Phys 2009, 130, 084105]. We show that this approach is computationally more efficient than the original hierarchical approach. The modified approach reduces the truncation levels of the auxiliary density operators and the correlation function. We provide a systematic study of how the number of auxiliary density operators and the higher-order correlation functions affect the exciton dynamics. The time scales of the coherent beating are consistent with experimental observations. Furthermore, our theoretical results exhibit population beating at physiological temperature. Additionally, the method does not require a low-temperature correction to obtain the correct thermal equilibrium at long times.
Wigner glass, spin liquids and the metal-insulator transition

Abstract Recent experiments on the two-dimensional electron gas in various semiconductor devices have shown an unexpected metal-insulator transition. These experimental results cannot be understood from the conventional perspective of weak interactions. We propose that: the low-density insulating state is the Wigner glass, a phase with quasi-long-range structural order and competing ferromagnetic and antiferromagnetic spin-exchange interactions; the transition is the melting of this Wigner glass, the disorder allowing the transition to be second order; within the Wigner glass phase there are at least two distinct magnetic ground states—a ferromagnetic state at very low electron density and a spin-liquid state with a spin pseudogap at higher densities; and the metallic side of the transition is a non-Fermi liquid. We present a proposed phase diagram as a function of disorder strength and density and suggest experimental signatures of the various phases and transitions.
IMPACT OF CORRUPTION ON FIRM-LEVEL EXPORT DECISIONS

This paper examines the impact of corruption on the self-selection of firms into domestic and export markets. A heterogeneous firm model predicts that corruption decreases the probability that a firm only sells domestically, increases the probability that a firm exports indirectly through an intermediary, and decreases the probability that a firm exports directly. The propositions of the model are tested using a comprehensive data set of over 23,000 firms in 80 developing countries. The results confirm both the self-selection of firms according to their productivity and the anticipated impact of corruption. This indicates that in developing countries where corruption is especially severe, intermediaries provide a crucial link to global markets.
Capsule endoscopy and deep enteroscopy

Abbreviations: CO 2 , carbon dioxide; DBE, double-balloon enteroscopy; MGCE, magnetic-guided capsule endoscopy; PC, patency capsule; PEG, polyethylene glycol; SBE, single-balloon enteroscopy; VCE, video capsule endoscopy
Local/Global Effects of Mistuning on the Forced Response of Bladed Disks

The focus of the percent investigation is on the assessment and modeling of the local (spanning only a few blades) and global (encompassing the entire disk) effects of mistiming on the forced response of bladed disks. To this end, the concept of localization is first revisited and a new measure of this effect is introduced in terms of the number of blades the mistuning of which actually affects the forced response of a central blade. Using this new metric, it is demonstrated that high responding blades typically exhibit a high level of localization and that the reverse is not necessarily true. Thus, localization is not only disk dependent but also varies from blade-to-blade on the same disk. This observation is then used to validate a partial mistiming approach to the determination of the maximum amplitude of response over the entire population of disks. The results of this study indicate that the largest amplification due to the mistuning occurs at very strong blade-to-blade coupling levels, at the contrary of a general perception, but is associated with large mistuning levels. Finally, the above phenomenological observations are used to devise a modeling technique of both local and global components of mistuning. An example of application is presented that demonstrates the high accuracy of this approach through the entire blade-to-blade coupling domain.
Going gently into flight: analyzing noncovalent interactions by mass spectrometry.

Dedicated to Professor John Fenn, recipient of the 2002 NobelPrize in Chemistry, for his extraordinary contributions to the development and implementation of electrospray mass spectrometry in the true spirit of scientific discovery and fun. Historically, mass spectrometry came of age during the heydey of organic chemicalanal ysis and structure determination, when the identification of molecular ions and their fragments complemented the fingerprinting of specific chemicalfunctionalgroups by infrared and ultraviolet spectroscopies. As ever larger (i.e., > 1000 Da) and more complex structures were characterized, increasingly by the use of NMR, mass spectrometry (MS) also rose to the challenge, with the development of newer ionization methods, including fast-atom bombardment 1 and matrix-assisted laser desorption ionization (MALDI) 2 techniques, as well as tandem 3 and secondary ion 4 mass spectrometry. Along the way, MS also made fundamental contributions to many other areas of chemistry, ranging from physicalstudies of the structures of gas-phase ions and their behavior, 5 to biological investigations of enzymatic reactions and other metabolic processes. 6
The Hippo pathway effector Yki downregulates Wg signaling to promote retinal differentiation in the Drosophila eye

The evolutionarily conserved Hippo signaling pathway is known to regulate cell proliferation and maintain tissue homeostasis during development. We found that activation of Yorkie (Yki), the effector of the Hippo signaling pathway, causes separable effects on growth and differentiation of the Drosophila eye. We present evidence supporting a role for Yki in suppressing eye fate by downregulation of the core retinal determination genes. Other upstream regulators of the Hippo pathway mediate this effect of Yki on retinal differentiation. Here, we show that, in the developing eye, Yki can prevent retinal differentiation by blocking morphogenetic furrow (MF) progression and R8 specification. The inhibition of MF progression is due to ectopic induction of Wingless (Wg) signaling and Homothorax (Hth), the negative regulators of eye development. Modulating Wg signaling can modify Yki-mediated suppression of eye fate. Furthermore, ectopic Hth induction due to Yki activation in the eye is dependent on Wg. Last, using Cut (Ct), a marker for the antennal fate, we show that suppression of eye fate by hyperactivation of yki does not change the cell fate (from eye to antenna-specific fate). In summary, we provide the genetic mechanism by which yki plays a role in cell fate specification and differentiation - a novel aspect of Yki function that is emerging from multiple model organisms.
Receiver function imaging in strongly laterally heterogeneous crust: Synthetic modeling of BOLIVAR data

We resolve a large (∼20 km) discrepancy in Moho depth determined from PdS receiver functions (RFs) and from active source seismic profiling in the complex Caribbean-South American plate boundary zone in eastern Venezuela. As part of the BOLIVAR experiment 20 broadband stations were deployed along an active source profile to record teleseisms. Using the extremely heterogeneous crustal model obtained from active source data, we generated 2D finite-difference elastic wave synthetics and from them calculated receiver functions and CCP stacks. We compare the observations with synthetic sections that have been spatially sampled at 0.25 km to 40 km. The densely sampled synthetics show that several events in the field data that were originally interpreted as the Moho are multiple reflections within sedimentary basins. Where the Moho has the steepest dip under the plate boundary the CCP stacks fail to image the Moho well, regardless of the density of spatial sampling. A suitable spatial sampling criterion for clearly imaging the lower crust and Moho is to overlap Fresnel zones by 50% at Moho depth, which for the 1 Hz receiver functions examined here, requires an instrument spacing of 15–20 km, with the actual field data density ranging from 20 km to 100 km.
A fracture mechanics approach to thermal fatigue life prediction of solder joints

A life prediction approach for solder joints under thermal fatigue, based on fracture mechanics and assuming that the thermal fatigue crack propagation in solder joints is primarily controlled by the C* and the J Integrals, is presented. The approach is applied to model experiments in which surface mounted electronic components were mounted on substrates with eutectic Pb/Sn solder joints and subjected to thermal cycling. The constitutive equation used for eutectic solder takes into account elasticity, time-independent plasticity, and power law secondary creep. Shear stress, strain components, and crack growth history in the solder joint are solved numerically by the Runge-Kutta method. The results are compared with both experimental data and predictions based on a modified Manson-Coffin equation. Good agreement is found between the present results and the experimental data, while the Manson-Coffin predictions are inconsistent with either the present ones or the experimental data. Examples illustrate how to apply the approach in order to design accelerated thermal cycling tests. >
MARKET STRUCTURE AND REPORTED TRADING VOLUME: NASDAQ VERSUS THE NYSE

Trading volume for common stocks is of interest to financial economists, investors, and securities lawyers. NASDAQ is a dealer market where trades with dealers are included in reported trading volume. This procedure does not accurately measure the trading volume by public buyers and sellers. Trading volume reported on the NYSE, which is primarily an auction market, provides a much closer measure of trades by public investors. We examine a sample of firms whose stock traded on the NASDAQ/NMS and subsequently on the NYSE. When trading switches to the NYSE, the firms' trading volume drops to about 50 percent of the volume previously reported on NASDAQ. A control group of firms that switched from the AMEX to the NYSE shows a small, but statistically insignificant, increase in trading volume.
Nuclear Instrumentation for Scintillation and Semiconductor Spectroscopy

A manual is presented for those who use or service the transistorized instruments for nuclear spectroscopy: the transistor amplifier; the snip-snap single-channel analyzer; the fast coincidence unit; and the biased amplifier and linear gate. A general description is given for each instrument along with the specifications, a description of the circuit, and a procedure for initial testing. (auth)
N-Pentafluorosulfanyl-N-nitro carbamates

Abstract Unlike N-alkyl carbamates, N-pentafluorosulfanyl carbamates (SF 5 NHCO 2 R) did not readily undergo nitration to provide the N-NO 2 derivatives. Although trifluoroacetyl nitrate did provide nitration, work-up yielded a mixture of SF 5 N(NO 2 )CO 2 R and starting material. The ratio of nitration product to starting material was not changed after prolonged reaction times and the N-NO 2 product was stable to the work-up conditions. A rationale for these results as well as the effect of varying R is discussed.
Location, Competition, and Economic Development: Local Clusters in a Global Economy

Economic geography during an era of global competition involves a paradox. It is widely recognized that changes in technology and competition have diminished many of the traditional roles of location. Yet clusters, or geographic concentrations of interconnected companies, are a striking feature of virtually every national, regional, state, and even metropolitan economy, especially in more advanced nations. The prevalence of clusters reveals important insights about the microeconomics of competition and the role of location in competitive advantage. Even as old reasons for clustering have diminished in importance with globalization, new influences of clusters on competition have taken on growing importance in an increasingly complex, knowledge-based, and dynamic economy. Clusters represent a new way of thinking about national, state, and local economies, and they necessitate new roles for companies, government, and other institutions in enhancing competitiveness.
Analysis of Homogeneous Charge Compression Ignition (HCCI) Engines for Cogeneration Applications

This paper presents an evaluation of the applicability of Homogeneous Charge Compression Ignition Engines (HCCI) for small-scale cogeneration (less than 1 MWe) in comparison to five previously analyzed prime movers. The five comparator prime movers include stoichiometric spark-ignited (SI) engines, lean burn SI engines, diesel engines, microturbines and fuel cells. The investigated option, HCCI engines, is a relatively new type of engine that has some fundamental differences with respect to other prime movers. Here, the prime movers are compared by calculating electric and heating efficiency, fuel consumption, nitrogen oxide (NOx) emissions and capital and fuel cost. Two cases are analyzed. In Case 1, the cogeneration facility requires combined power and heating. In Case 2, the requirement is for power and chilling. The results show that the HCCI engines closely approach the very high fuel utilization efficiency of diesel engines without the high emissions of NOx and the expensive diesel fuel. HCCI engines offer a new alternative for cogeneration that provides a unique combination of low cost, high efficiency, low emissions and flexibility in operating temperatures that can be optimally tuned for cogeneration systems. HCCI engines are the most efficient technology that meets the oncoming 2007 CARB NOx standards for cogenerationmore » engines. The HCCI engine appears to be a good option for cogeneration systems and merits more detailed analysis and experimental demonstration.« less
Simulations of second-order Fermi acceleration of electrons: solving the injection problem

The boosting of electrons from a Maxwellian distribution into a suprathermal power-law tail is studied, using a test-particle simulation code, following the full equations of motion of tens of thousands of electrons chosen from a thermal population as they move through general time-dependent magnetic fields. This distinguishes between bulk heating of the electron population or boosting of selected electrons. Which of these occurs is found to depend on the size of the swarm thermal speed compared with the electron thermal speed. >