cssi/SciSciGPT-SciSciNet huggingface dataset:
The flux and source of energetic protons in Saturn's inner magnetosphere

The flux of energetic protons in Saturn's inner magnetosphere was observed in two channels from 48 to 63 and 63 to 160 MeV. Absorption features due to the G ring and the satellites Enceladus and Mimas were easily identifiable. The flux observed in the absorption slot of Mimas can be maintained by the decay of a cosmic ray albedo neutron flux of 0.007/sq cm/s/sr. This flux is entirely consistent with calculations of the neutron flux produced by galactic cosmic ray interactions with the rings of Saturn. The omnidirectional proton flux of 0.0082/sq cm/s at 2.734 R sub s requires a residence time of 30 years. Both the residence time and the energy spectrum are comparable to those found in the inner radiation belt of the Earth. The angular distribution is nearly isotropic in the Mimas slot and beyond 4R sub s. Otherwise the pitch angle distribution is pancake and is approximated by sin(n)theta with n in the range 2 to 7. This distribution is consistent with an isotropic neutron source in the ring plane.
A bio-physically inspired silicon neuron

The physical principles governing ion flow in biological neurons share interesting similarities to electron flow through the channels of MOSFET transistors. Here, is described a circuit which exploits the similarities better than previous approaches to build an elegant circuit with electrical properties similar to real biological neurons. A two-channel model is discussed including sodium (Na/sup +/) and potassium (K/sup +/). The Na/sup +/ channel uses four transistors and two capacitors. The K/sup +/ channel uses two transistors and one capacitor. One more capacitor simulates the neuron membrane capacitance yielding a total circuit of four capacitors and six transistors. This circuit operates in real-time, is fabricated on standard CMOS processes, runs in subthreshold, and has a power supply similar to that of real biology. Voltage and current responses of this circuit correspond well with biology in terms of shape, magnitude, and time.
The size matching and scaling method: a synthesis method for the design of mesoscale cellular structures

Mesoscale lattice structures are a type of cellular structure with support element lengths on the order of magnitude of centimetres. These types of structures are engineered for high performance and are used particularly in industries where low weight and high strength are desired. However, designing these structures can be difficult because they can contain thousands of individual elements. To design mesoscale lattice structures, current synthesis methods generally require some form of rigorous, multi-variable optimisation that can slow or halt the design process. In this article, we present an alternative method for the design of mesoscale lattice structures: the size matching and scaling method. This method eliminates the need for time-consuming optimisation by using a combination of a solid-body finite element analysis and a library of pre-defined lattice configurations to generate a structure's lattice topology. In addition, we explore several methods for determining the best lattice diameter values for the lattice topology. Various 2D and 3D examples will be used to test and validate the method.
Energy-Technology Innovation

▪ Abstract Energy-technology innovation (ETI) is the set of processes leading to new or improved energy technologies that can augment energy resources; enhance the quality of energy services; and reduce the economic, environmental, or political costs associated with energy supply and use. Advances achieved through ETI have made large contributions to the improvement of the human condition over the past 100 years. Still more will be required of ETI during the decades ahead if civilization is to succeed in meeting what we believe are the three greatest energy challenges still before it: reducing dependence on oil, drastically upgrading the energy services provided to the world's poor, and providing the energy required to increase and sustain prosperity everywhere without wrecking the global climate with the emissions from fossil-fuel burning. This will require significant enhancements to ETI through deeper analysis of ETI processes, greater investments in ETI, improved innovation policies, and better coordi...
Stereoselective synthesis of substituted ketopyranose subunits of polyketide natural products by intramolecular alkoxycarbonylation of δ-alkynyl alcohols

Abstract Upon treatment with 5 mol% Pd(MeCN)2Cl2 in methanol containing 1.1–1.5 equiv. of p-benzoquinone under 1 atm of CO, δ-hydroxy alkynes are converted to methyl ketopyranosides with excellent stereoselectivity. The reaction proceeds by sequential intramolecular alkoxypalladation of the alkyne followed by CO insertion and methanolysis, then an ensuing Pd+2-catalyzed 1,4-addition of methanol to the intermediate conjugated ester.
TOR signaling regulates planarian stem cells and controls localized and organismal growth

Target of Rapamycin (TOR) controls an evolutionarily conserved signaling pathway that modulates cellular growth and division by sensing levels of nutrients, energy and stress. As such, TOR signaling is a crucial component of tissues and organs that translates systemic signals into cellular behavior. The ubiquitous nature of TOR signaling, together with the difficulty of analyzing tissue during cellular turnover and repair, have limited our understanding of how this kinase operates throughout the body. Here, we use the planarian model system to address TOR regulation at the organismal level. The planarian TOR homolog (Smed-TOR) is ubiquitously expressed, including stem cells (neoblasts) and differentiated tissues. Inhibition of TOR with RNA interference severely restricts cell proliferation, allowing the study of neoblasts with restricted proliferative capacity during regeneration and systemic cell turnover. Strikingly, TOR signaling is required for neoblast response to amputation and localized growth (blastema). However, in the absence of TOR signaling, regeneration takes place only within differentiated tissues. In addition, TOR is essential for maintaining the balance between cell division and cell death, and its dysfunction leads to tissue degeneration and lack of organismal growth in the presence of nutrients. Finally, TOR function is likely to be mediated through TOR Complex 1 as its disruption recapitulates signs of the TOR phenotype. Our data reveal novel roles for TOR signaling in controlling adult stem cells at a systemic level and suggest a new paradigm for studying TOR function during physiological turnover and regeneration.
Thrust and ignition transients of the Space Shuttle solid rocket motor

Techniques developed for predicting and analyzing ignition, pressurization, and thrust transients in large segmented motors were applied to the four developmental Space Shuttle solid rocket motors. Following the first test, attention was focused on understanding dynamic thrust and the rate of thrust increase during pressurization and predicting effects of reduced igniter mass flow rate and gas temperature. The close coupling between the igniter and the head-end segment and the high length-to-diameter ratio make understanding of the longitudinal pressure waves essential. The igniter performance along with igniter to head-end segment geometry govern the induction interval and head-end segment ignition. Following ignition of the head-end segment, subsequent flame spreading and pressurization tend to be motor properties which are not appreciably altered by changes in the head-end igniter mass flow rate.
Zirconocene(iso-butyl) chloride: In situ generation of a zirconocene(methyl) chloride equivalent for use in organic synthesis

Abstract Zirconocene( iso -butyl) chloride, 1 , which can be generated in situ from commercially available, inexpensive, and air-stable zirconocene dichloride, can function as a zirconocene(methyl) chloride equivalent.
Extraction of wafer-level defect density distributions to improve yield prediction

Defect density distributions play an important role in process control and yield prediction. To improve yield prediction we present a methodology to extract wafer-level defect density distributions better reflecting such chip-to-chip defect density variations that occur in reality. For that, imaginary wafermaps are generated for a variety of different chip areas to calculate a yield-to-area dependency. Based on these calculations a micro density distribution (MDD) will be determined for each wafer that reflects the degree of defect clustering. The single MDD's per wafer may be summarized to also provide a total defect density distribution per lot or any other sample size. Furthermore, the area needed for defect inspection may be reduced to just a fraction of each wafer which reduces time and costs of data collection and analysis.
Variations in organic aerosol optical and hygroscopic properties upon heterogeneous OH oxidation

[1] Measurements of the evolution of organic aerosol extinction cross sections (σext) and subsaturated hygroscopicity upon heterogeneous OH oxidation are reported for two model compounds, squalane (a C30 saturated hydrocarbon) and azelaic acid (a C9 dicarboxylic acid). For both compounds, the σext values at 532 nm increase substantially as the particles undergo oxidation, exhibiting a logarithmic increase with OH exposure. The increase in σext correlates with both an increase in the particle oxygen to carbon (O:C) atomic ratio and density and a decrease in mean molecular weight. The measurements have been used to calculate the variation with oxidation of the mean polarizability, α, of the molecules comprising the particles. The absolute α values for the two systems are shown to be related through the variation in the particle chemical composition, specifically the relative abundances of C, O, and H atoms and the mean molecular weight. Unlike σext, it was found that the evolution of the particle hygroscopicity upon oxidation is quite different for the two model systems considered. Hygroscopicity was quantified by measuring γext, which is a single-parameter representation of hygroscopicity that describes the increase in extinction upon exposure of the particles to a high–relative humidity environment (here, 75% and 85% RH). For unoxidized squalane, γext was zero and only increased slowly as the particles were oxidized by OH radicals. In contrast, γext for azelaic acid increased rapidly upon exposure to OH, eventually reaching a plateau at high OH exposures. In general, γext appears to vary sigmoidally with O:C, reaching a plateau at high O:C.
The case for durative actions: a commentary on PDDL2.1

The addition of durative actions to PDDL2.1 sparked some controversy. Fox and Long argued that actions should be considered as instantaneous, but can start and stop processes. Ultimately, a limited notion of durative actions was incorporated into the language. I argue that this notion is still impoverished, and that the underlying philosophical position of regarding durative actions as being a shorthand for a start action, process, and stop action ignores the realities of modelling and execution for complex systems.
Excessive Labour Raiding

Final version received 24 July 2006.Labour raiding refers to ﬁrms recruiting and hiring employed workers. The literature on labour raidingsupports the idea that raiding sorts workers into their most productive positions. I present a model wherean outside ﬁrm decides whether or not to pay to learn the match-quality of an employed worker and theemployer decides whether or not to pay its worker a high wage that pre-empts the raiding. I show that theemployer may pay a low wage and gamble that it will not be raided rather than use a pre-emptive wage.This leads to an excessive amount of raiding.
B- AND A-TYPE STARS IN THE TAURUS-AURIGA STAR-FORMING REGION

We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared images show bright nebulae, all of which can be associated with stars of spectral-type B. The second group consists of early-type stars compiled from (1) literature listings in SIMBAD, (2) B stars with infrared excesses selected from the Spitzer Space Telescope survey of the Taurus cloud, (3) magnitude- and color-selected point sources from the Two Micron All Sky Survey, and (4) spectroscopically identified early-type stars from the Sloan Digital Sky Survey coverage of the Taurus region. We evaluated stars for membership in the Taurus-Auriga star formation region based on criteria involving: spectroscopic and parallactic distances, proper motions and radial velocities, and infrared excesses or line emission indicative of stellar youth. For selected objects, we also model the scattered and emitted radiation from reflection nebulosity and compare the results with the observed spectral energy distributions to further test the plausibility of physical association of the B stars with the Taurus cloud. This investigation newly identifies as probable Taurus members three B-type stars: HR 1445 (HD 28929), τ Tau (HD 29763), 72 Tau (HD 28149), and two A-type stars: HD 31305 and HD 26212, thus doubling the number of stars A5 or earlier associated with the Taurus clouds. Several additional early-type sources including HD 29659 and HD 283815 meet some, but not all, of the membership criteria and therefore are plausible, though not secure, members.
Testing State-Space Controls for the Controls Advanced Research Turbine

Control can improve wind turbine performance by enhancing energy capture and reducing dynamic loads. At the National Renewable Energy Laboratory, we are implementing and testing state-space controls on the controls advanced research turbine (CART), a turbine specifically configured to test advanced controls. We show the design of control systems to regulate turbine speed in region 3 using rotor collective pitch and reduce dynamic loads in regions 2 and 3 using generator torque. These controls enhance damping in the first drive train torsion mode. We base these designs on sensors typically used in commercial turbines. We evaluate the performance of these controls by showing field test results. We also compare results from these modern controllers to results from a baseline controller for the CART. Finally, we report conclusions to this work and outline future studies.
Berkeley Supernova Ia Program – III. Spectra near maximum brightness improve the accuracy of derived distances to Type Ia supernovae

In this third paper in a series we compare spectral feature measurements to photometric properties of 108 low-redshift (z < 0.1, 〈z〉 ≈ 0.023) Type Ia supernovae (SNe Ia) for which we have optical spectra within 5 d of maximum brightness. The spectral data were obtained from 1989 to the end of 2008 as part of the Berkeley Supernova Ia Program (BSNIP) and are presented in BSNIP I by Silverman et al., and the photometric data come mainly from the Lick Observatory Supernova Search and are published by Ganeshalingam et al. The spectral measurements are presented and discussed in BSNIP II by Silverman, Kong & Filippenko, and the light-curve fits and photometric parameters can be found in Ganeshalingam et al. (in preparation). A variety of previously proposed correlations between spectral and photometric parameters are investigated using the large and self-consistent BSNIP data set. We find the pseudo-equivalent width (pEW) of the Si ii λ4000 line to be a good indicator of light-curve width, and the pEWs of the Mg ii and Fe ii complexes are relatively good proxies for SN colour. We also employ a combination of light-curve parameters (specifically the Spectral Adaptive Light-curve Template 2 stretch and colour parameters x1 and c, respectively) and spectral measurements to calculate distance moduli. The residuals from these models are then compared to the standard model which uses only light-curve stretch and colour. Our investigations show that a distance model that uses x1, c and the velocity of the Si ii λ6355 feature does not lead to a decrease in the Hubble residuals. We also find that distance models with flux ratios alone or in conjunction with light-curve information rarely perform better than the standard (x1, c) model. However, when adopting a distance model which combines the ratio of fluxes near ∼3750 and 4550 A with both x1 and c, the Hubble residuals are decreased by ∼10 per cent, which is found to be significant at about the 2σ level. The weighted root mean square of the residuals using this model is 0.130 ± 0.017 mag (as compared with 0.144 ± 0.019 mag when using the same sample with the standard model). This Hubble diagram fit has one of the smallest scatters ever published and at the highest significance ever seen in such a study. Finally, these results are discussed with regard to how they can improve the cosmological accuracy of future, large-scale SN Ia surveys.
IMM estimator with out-of-sequence measurements

In multisensor tracking systems that operate in a centralized information processing architecture, measurements from the same target obtained by different sensors can arrive at the processing center out of sequence. In order to avoid either a delay in the output or the need for reordering and reprocessing an entire sequence of measurements, such measurements have to be processed as out-of-sequence measurements (OOSMs). Recent work developed procedures for incorporating OOSMs into a Kalman filter (KF). Since the state of the art tracker for real (maneuvering) targets is the interacting multiple model (IMM) estimator, the algorithm for incorporating OOSMs into an IMM estimator is presented here. Both data association and estimation are considered. Simulation results are presented for two realistic problems using measurements from two airborne GMTI sensors. It is shown that the proposed algorithm for incorporating OOSMs into an IMM estimator yields practically the same performance as the reordering and in-sequence reprocessing of the measurements. Also, it is shown how the range rate from a GMTI sensor can be used as a linear velocity measurement in the tracking filter.
High real interest rates, guarantor risk, and bank recapitalizations

The author sets out a methodology for analyzing episodes of high real interest rates in emerging market economies. He reviews the literature on what determines spreads in deposit rates and loan rates. Then he links the causes of interest rate spreads by explicitly modeling the incentive effect of a government deposit guarantee on the behavior of depositories, banks, and firms. The premise: begin with accounting identities that decompose the deposit spread and loan spread into several components. The relative importance of the components can be measured to discover the sources of the high real rates. The results suggest that the expected exchange rate depreciation and credit quality of borrowers are among the most important determinants of high real rates. A government guarantee on deposits affects both the deposit and the loan spread by altering marginal incentives. Although high real rates may signal financial distress, standard recapitulation mechanisms may not improve the situation. The behavior of real interest rates depends on the account unit that has been chosen for financial transaction. High real interest rates often occur when an economy is close to widespread debtor default. If high real interest rates are a financial sector distress symptom, then high real rates will incorporate expectations of a breakdown in the government's enforcement of financial contracts, in addition to other factors the author addresses.
Random response of beams and plates with slipping at support boundaries

A numerical and experimental s tudy is made of the response to random excitation of a beam and rectangular plate w ith dry friction damping due to slipping at the support boundaries. The design of the beam experimental a pparatus and the utilization of the associated instrumentation are described. Comparisons of the experimental results with those o btained from an approximate analytical solution and also to the r esults from numerical simulations are made. The good agreement among these several results shows that the concept of an equivalent linear viscous damping due to slipping at t he support boundaries often can be usefully applied to determine the resDonse due to random excitation. This approach, nonlinear when appl'icable, greatly simplifies the random vibration prob! em. Nomenclature beam or plate length, cm modal generalized c oordi nate, cm plate width, cm see Eq. (9)
Decameter-scale pedestal craters in the tropics of Mars: Evidence for the recent presence of very young regional ice deposits in Tharsis

Abstract Global climate models predict that ice will be deposited in tropical regions during obliquity excursions from the current mean obliquity of ~ 25° to ~ 35°, but no geological evidence for such deposits has been reported. We document the presence of very small (decameter scale) pedestal craters in the tropics of Mars (the Daedalia Planum–Tharsis region) that are superposed on an impact crater dated to ~ 12.5 Ma ago. The characteristics, abundance, and distribution of these small pedestal craters provide geological evidence that meters-thick ice accumulations existed in the tropical Tharsis region of Mars in the last few million years when mean obliquity was ~ 35° (~ 5–15 Ma) before it transitioned to a mean of ~ 25° (~ 0–3 Ma). A reconnaissance survey reveals similar small pedestal crater examples superposed on the older Amazonian Arsia Mons tropical mountain glacier deposit, suggesting that ice can accumulate in these tropical regions without initiating large-scale glacial conditions. These results support the predictions of general circulation models that ice can migrate to the equatorial regions during periods of moderate obliquity and then serve as a source for mid-latitude deposits.
Additive Fabrication and the Mechanisms of Nucleation and Growth in Chemical Vapor Deposition Processes

In this Account, we present several representative studies of thin-film growth by chemical vapor deposition, with particular emphasis given to elucidating the mechanistic, energetic, and structural aspects of nucleation and growth. These understandings have allowed us to develop new methods to deposit patterned, as opposed to blanket, thin films. We show how such procedures can be exploited to effect the directed assembly (i.e., the additive fabrication) of a device architecture.
Rapid, effective deprotection of tert-butoxycarbonyl (Boc) amino acids and peptides at high temperatures using a thermally stable ionic liquid

A method for high temperature Boc deprotection of amino acids and peptides in a phosphonium ionic liquid is described. The ionic liquid had low viscosity, high thermal stability and demonstrated a beneficial effect. The study extended the possibility for extraction of water soluble polar organic molecules using ionic liquids. Trace water significantly improved product purity and yield, while only 2 equiv. TFA led to deprotection within 10 min. The trityl group was also deprotected.
Reform of the Aeronautics and Astronautics Curriculum at MIT

Over the course of two and one half years, the faculty of the Department of Aeronautics and Astronautics at MIT have thoroughly revised the undergraduate SB curriculum and created a new fifth year MEng program. The goal of the undergraduate program is a strong preparation in fundamentals taught in the context of aerospace systems. The curriculum exposes the students to the breadth of disciplines essential to modern engineering practice, with new emphasis on aerospace decision information and control. The fifth year MEng will be more structured than traditional research oriented Masters programs. It will be highly coordinated with the four year undergraduate program, and include a year long design project thesis.
Simulations of dielectric Cerenkov masers at moderate to high power

Summary form only given. A dielectric Cerenkov maser amplifier is simulated with XOOPIC and results are compared to experiment and theory. The device examined is azimuthally symmetric with a circular cross section. A magnetically confined annular electron beam at 79 keV and 7 A interacts with the slow wave structure to produce the radiation. The outer guide radius is 6.25 cm, with a 2.19 cm thick smooth dielectric liner of permittivity /spl epsiv//sub /spl tau//=4.2. The applied magnetic field is 0.1 T. These parameters are very close to a series of experiments at Dartmouth (Von Laven, 1982), which demonstrated output powers in the range of 300-100 kW at 10-50 GHz with 10% efficiency when operating in the TM/sub 01/ mode. The dispersion has been obtained and agrees well with the experiment. The efficiency, power, and gain will be compared for the parameters of the Dartmouth experiment.
Quantum measurements of trapped ions

Abstract When a quantum state is subjected to a measurement and the state is not an eigenstate of the dynamical variable being measured, the outcome is unpredictable. Only the probabilities of the various possible outcomes are predicted by theory. This phenomenon is sometimes discussed in terms of “wavefunction collapse.” Trapped ions can be used for real, as opposed to gedanken demonstrations of this basic process. In the experiments described here, a single ion, or a few identical ions, were prepared in well defined superpositions of two internal energy eigenstates. The populations of the energy levels were then measured. When the state amplitudes were equal, the population fluctuations were greater than when one of the amplitudes was nearly zero, in agreement with the predictions of quantum mechanics. In other experiments, such as those with atomic beams, the number of atoms under observation fluctuates, and this obscures the fluctuations from other sources. However, if the number of atoms is small and constant, the fundamental quantum mechanical fluctuations can be observed.
Aerodynamic Tests of Darrieus Wind Turbine Blades

An indoor facility for the aerodynamic testing of Darrieus turbine blades was developed. Lift, drag, and moment coefficients were measured for two blades whose angle of attack and chord-to-radius ratio were varied. The first blade used an NACA 0015 airfoil section; the second used a 15% elliptical cross section with a modified circular arc trailing edge. Blade aerodynamic coefficients were corrected to section coefficients for comparison to published rectilinear flow data. Although the airfoil sections were symmetrical, moment coefficients were not zero and the lift and drag curves were asymmetrical about zero lift coefficient and angle of attack. These features verified the predicted virtual camber and incidence phenomena. Boundary-layer centrifugal effects were manifested by discontinuous lift curves and large differences in the angle of zero lift between the NACA 0015 and elliptical airfoils. It was concluded that rectilinear flow aerodynamic data are not applicable to Darrieus turbine blades, even for small chord-to-radius ratios. Nomenclature b, C = blade span and chord ci>cd>cm = section li ft, drag, and moment coefficient CL, CD, CM = blade lift, drag, and moment coefficient cl , CL = section and blade lift curve slope, per degree Cp a = rotor power coefficient, the ratio of power extracted to energy theoretically available in the wind Cu = circulation control blowing coefficient
Synthesis of 1,2-Dioxolanes by Annulation Reactions of Peroxycarbenium Ions with Alkenes

[reaction: see text] The annulation reactions of alkenes with peroxycarbenium ions enable the synthesis of a variety of functionalizable 1,2-dioxolanes. Triethysilyl-protected peroxycarbenium ions proved to be optimal for the annulation reaction. Using this method, plakinic acid analogues can be synthesized in three steps from the corresponding ketone and alkene.
The Exchange Value Embedded in a Transport System

This paper shows that a well designed transport system has an embedded exchange value by serving as a market for potential exchange between consumers. Under suitable conditions, one can improve the welfare of consumers in the system simply by allowing some exchange of goods between consumers during transportation without incurring additional transportation cost. We propose an explicit valuation formula to measure this exchange value for a given compatible transport system. This value is always nonnegative and bounded from above. Criteria based on transport structures, preferences and prices are provided to determine the existence of a positive exchange value. Finally, we study a new optimal transport problem with an objective taking into account of both transportation cost and exchange value.
A fast multilayer general area router for MCM designs

The authors report on the development of an efficient multilayer general area router as an alternative to the three-dimensional (3-D) maze router for solving the multilayer multichip module (MCM) routing problem. The router, named SLICE, is independent of net ordering, requires much shorter computation time, and uses fewer vias. A key step in the router is to compute a maximum non-crossing bipartite matching, which is solved optimally in O(n log n) time where n is the number of possible connections. The router was tested on a number of examples, including two MCM designs. Compared to a 3-D maze router, SLICE is four times faster and uses 28% fewer vias. SLICE can successfully produce solutions for large MCM routing examples where 3-D maze routers fail due to insufficient memory. >
Alkylation of benzene with 1-alkenes over beta zeolite in liquid phase

Alkylation of benzene with 1-alkenes (C6–C18) was performed in liquid phase at 160–200 °C over beta zeolites with Si/A molar ratio 12.5–75.0. With increasing alkyl chain length, the conversion of 1-alkene decreased. The alkylation activity decreased with increasing Si/Al ratio of beta-zeolite. The increase of Si/Al molar ratio was connected with the enhancement of the portion of Lewis acid sites in total acidity of beta zeolites, resulting in greater dimerization/oligomerization activity and consequently in more rapid deactivation of beta-zeolites.
Using Online Conversations to Study Word-of-Mouth Communication

Managers are very interested in word-of-mouth communication because they believe that a product's success is related to the word of mouth that it generates. However, there are at least three significant challenges associated with measuring word of mouth. First, how does one gather the data? Because the information is exchanged in private conversations, direct observation traditionally has been difficult. Second, what aspect of these conversations should one measure? The third challenge comes from the fact that word of mouth is not exogenous. While the mapping from word of mouth to future sales is of great interest to the firm, we must also recognize that word of mouth is an outcome of past sales. Our primary objective is to address these challenges. As a context for our study, we have chosen new television (TV) shows during the 1999-2000 seasons. Our source of word-of-mouth conversations is Usenet, a collection of thousands of newsgroups with diverse topics. We find that online conversations may offer an easy and cost-effective opportunity to measure word of mouth. We show that a measure of the dispersion of conversations across communities has explanatory power in a dynamic model of TV ratings.
Searches for new physics in photonic final states at LEP

A brief review of searches for physics beyond the Standard Model in photonic final states at LEP is given here. These include searches for supersymmetry, large extra dimensions and contact interactions. Recent results from all four LEP experiments are presented, including improved limits on the new scale of gravity for models with large extra dimensions and the most precise direct measurement of the number of light neutrino species. Status and prospects of the LEP combined searches are also discussed. PACS: 13.66.Hk Production of non-standard model particles in e+e– interactions – 04.50.+h Gravity in more than four dimensions – 12.60.Jv Supersymmetric models – 12.60.-i Models beyond the standard model – 13.15.+g Neutrino interactions
Experiments on the Diffusion of Smoke in Isotropic Turbulent Flow

Detailed properties of the downstream evolution of smoke released in an isotropic turbulent flowfield are reported. Effects of turbulence on the mass-transfer characteristics of the flow, which in turn affect such things as the spread of pollution and the rate of chemical reactions, are studied. Smoke is released a short distance downstream of a uniform grid placed perpendicular to a uniform stream of air in a wind tunnel. A laser Doppler velocimeter is used to make the desired velocity field measurements, and a laser light-scatttering technique provides the "instantaneous11 mass fraction c of smoke at the same point in the flowfield. One-point statistical properties of the velocity and concentration fields are obtained. The one-point cross correlations cu and cv are also reported.
Self-pumped phase-conjugate fiber-optic gyro

We describe a new type of phase-conjugate fiber-optic gyro that uses self-pumped phase conjugation. The self-pumped configuration is simpler than externally pumped configurations and permits the use of sensing fibers longer than the coherence length of the laser. A proof-of-principle demonstration of rotation sensing with the device is presented.
THE CENTRAL X-RAY POINT SOURCE IN CASSIOPEIA A

The spectacular ii —rst light ˇˇ observation by the Chandra X-Ray Observatory revealed an X-ray point source near the center of the 300 yr old Cas A supernova remnant. We present an analysis of the public X-ray spectral and timing data. No coherent pulsations were detected in the Chandra/HRC data. The 3 p upper limit on the pulsed fraction is less than 35% for P ( 20 ms. The Chandra/ACIS spectrum of the point source may be —tted with an ideal blackbody (kT \ 0.5 keV) or with blackbody models modi—ed by the presence of a neutron star atmosphere (kT \ 0.25¨0.35 keV), but the temperature is higher and the inferred emitting area lower than expected for a 300 yr old neutron star according to standard cooling models. The spectrum may also be —tted with a power-law model (photon index ! \ 2.8¨3.6). Both the spectral properties and the timing limits of the point source are inconsistent with a young Crab-like pulsar but are quite similar to the properties of the anomalous X-ray pulsars. The spectral parameters are also very similar to those of the other radio-quiet X-ray point sources in the supernova remnants Pup A, RCW 103, and PKS 1209(52. Current limits on an optical counterpart for the Cas A point source rule out models that invoke fallback accretion onto a compact object if fallback disk properties are similar to those in quiescent low-mass X-ray binaries. However, the optical limits are mar- ginally consistent with plausible alternative assumptions for a fallback disk. In this case, accreting neutron star models can explain the X-ray data, but an accreting black hole model is not promising. Subject headings: accretion, accretion disksblack hole physicsstars: neutron ¨ supernovae: individual (Cassiopeia A) ¨ supernova remnantsX-rays: stars
An Accurate Calculation of the Big Bang Prediction for the Abundance of Primordial Helium

Within the standard models of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of ${}^{4}\mathrm{He}$ to a theoretical uncertainty of less than $0.1% (\ensuremath{\delta}{Y}_{P}l\ifmmode\pm\else\textpm\fi{}0.0002),$ improving the current theoretical precision by a factor of 10. At this accuracy the uncertainty in the abundance is dominated by the experimental uncertainty in the neutron mean lifetime, ${\ensuremath{\tau}}_{n}=885.4\ifmmode\pm\else\textpm\fi{}2.0 \mathrm{sec}.$ The following physical effects were included in the calculation: the zero and finite-temperature radiative, Coulomb and finite-nucleon-mass corrections to the weak rates; order-$\ensuremath{\alpha}$ quantum-electrodynamic correction to the plasma density, electron mass, and neutrino temperature; and incomplete neutrino decoupling. New results for the finite-temperature radiative correction and the QED plasma correction were used. In addition, we wrote a new and independent nucleosynthesis code designed to control numerical errors to be less than 0.1% . Our predictions for the ${}^{4}\mathrm{He}$ abundance are presented in the form of an accurate fitting formula. Summarizing our work in one number, ${Y}_{P}(\ensuremath{\eta}=5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10})=0.2462\ifmmode\pm\else\textpm\fi{}0.0004 (\mathrm{expt})\ifmmode\pm\else\textpm\fi{}l0.0002 (\mathrm{theory}).$ Further, the baryon density inferred from the Burles-Tytler determination of the primordial D abundance, ${\ensuremath{\Omega}}_{B}{h}^{2}=0.019\ifmmode\pm\else\textpm\fi{}0.001,$ leads to the prediction ${Y}_{P}=0.2464\ifmmode\pm\else\textpm\fi{}0.0005 (\mathrm{D}/\mathrm{H})\ifmmode\pm\else\textpm\fi{}l0.0002 (\mathrm{theory})\ifmmode\pm\else\textpm\fi{}0.0005 (\mathrm{expt}).$ This ``prediction'' and an accurate measurement of the primeval ${}^{4}\mathrm{He}$ abundance will allow an important consistency test of primordial nucleosynthesis.
Longitudinal phase space computer simulation of IUCF cooler ring multiturn stacking injection

The longitudinal phase space computer simulation of multiturn RF stacking injection and the preliminary experimental results of stacking at the IUCF (Indiana University Cyclotron Facility) are discussed. The simulation considered effects such as oscillatory ripples on the cooling stack orbit due to the debunching RF voltage, finite slew rate of RF modulations, and compromised choices of bucket height, debunching linearity, and deceleration speed. The simulation was found to be very helpful in gaining a quantitative understanding of RF stacking and was also found to be instrumental in specifying software and hardware parameters. Also reported is a 120-MeV polarized proton test, during which about 50 nA of beam was stacked and cooled with six turn injections. Results indicate that the stacked beam could only survive a limited number of kicker firings. >
Haglund’s conjecture on 3-column Macdonald polynomials

We prove a positive combinatorial formula for the Schur expansion of LLT polynomials indexed by a 3-tuple of skew shapes. This verifies a conjecture of Haglund (Proc Natl Acad Sci USA 101(46):16127–16131, 2004). The proof requires expressing a noncommutative Schur function as a positive sum of monomials in Lam’s (Eur J Combin 29(1):343–359, 2008) algebra of ribbon Schur operators. Combining this result with the expression of Haglund et al. (J Am Math Soc 18(3):735–761, 2005) for transformed Macdonald polynomials in terms of LLT polynomials then yields a positive combinatorial rule for transformed Macdonald polynomials indexed by a shape with 3 columns.
Annulation of heterocyclic rings on aromatic templates: The quinone monoketal route

Abstract A double conjugate addition sequence anneals heterocyclic rings onto a 2-alkyl quinone monoketal intermediate. This operation, reminiscent of a Barco annulation, proceeds in excellent overall yield. The new chemistry offers interesting opportunities in alkaloid synthesis.
Group variable selection via a hierarchical lasso and its oracle property

In many engineering and scientific applications, prediction variables are grouped, for example, in biological applications where assayed genes or proteins can be grouped by biological roles or biological pathways. Common statistical analysis methods such as ANOVA, factor analysis, and functional modeling with basis sets also exhibit natural variable groupings. Existing successful group variable selection methods have the limitation of selecting variables in an “allin-all-out” fashion, i.e., when one variable in a group is selected, all other variables in the same group are also selected [1, 23, 25]. In many real problems, however, we may want to keep the flexibility of selecting variables within a group, such as in gene-set selection. In this paper, we develop a new group variable selection method that not only removes unimportant groups effectively, but also keeps the flexibility of selecting variables within a group. We also show that the new method offers the potential for achieving the theoretical “oracle” property [6, 7].
Domain walls with strings attached

We have constructed a bulk & brane action of IIA theory which describes a pair of BPS domain walls on S-1/Z(2), with strings attached. The walls are given by two orientifold O8-planes with coincident D8-branes and 'F1-D0'-strings are stretched between the walls. This static configuration satisfies all matching conditions for the string and domain wall sources and has 1/4 of unbroken supersymmetry.
The Potential-Density Phase-Shift Method for Determining the Corotation Radii in Spiral and Barred Galaxies

We have developed a new method for determining the corotation radii of density waves in disk galaxies, which makes use of the calculated radial distribution of an azimuthal phase shift between the potential and density wave patterns. The approach originated from improved theoretical understanding of the relation between the morphology and kinematics of galaxies and of the dynamical interaction between density waves and the basic-state disk stars, which results in the secular evolution of disk galaxies. In this paper we present the rationales behind the method and the first application of it to several representative barred and grand-design spiral galaxies, using near-infrared images to trace the mass distributions, as well as to calculate the potential distributions used in the phase-shift calculations. We compare our results with those from other existing methods for locating the corotations and show that the new method both confirms the previously established trends of bar-length dependence on galaxy morphological types and provides new insights into the possible extent of bars in disk galaxies. The method also facilitates the estimation of mass accretion/excretion rates due to bar and spiral density waves, providing an alternative way of quantifying the importance of these features in disk galaxies. A preliminary analysis of a larger sample shows that the phase-shift method is likely to be a generally applicable, accurate, and essentially model-independent method for determining the pattern speeds and corotation radii of single or nested density wave patterns in galaxies. Other implications of the results of this work include that most of the nearby bright disk galaxies appear to possess quasi-stationary spiral modes; that these density wave modes, as well as the associated basic states of the galactic disks, slowly transform over the time span of a Hubble time due to a collective dissipation process directly related to the presence of the phase shift between the potential and density patterns; and that self-consistent N-particle systems contain physics not revealed by the passive orbit analysis approaches.
Noise reduction in state space using the focused gamma neural network

In this paper we utilize the gamma neural model to improve the signal to noise ratio (SNR) of broadband signals corrupted by white noise. The projection of a noisy signal onto the signal subspace can not remove the noise in the subspace. A focus gamma network, when trained as a nonlinear predictor of the projected trajectory, reduces this noise further. The property of adaptive memory depth of the gamma model is utilized to decide when to stop the training of the network. The preliminary results show that the SNR can be improved significantly, preserving the broadband signal spectrum. >
Programming-in-the-Large Versus Programming-in-the-Small

We distinguish the activity of writing large programs from that of writing small ones. By large programs we mean systems consisting of many small programs (modules), possibly written by different people.We need languages for programming-in-the-small, i.e. languages not unlike the common programming languages of today, for writing modules. We also need a “module interconnection language” for knitting those modules together into an integrated whole and for providing an overview that formally records the intent of the programmer(s) and that can be checked for consistency by a compiler.We explore the software reliability aspects of such an interconnection language. Emphasis is placed on facilities for information hiding and for defining layers of virtual machines.
Synchronized Formation Rotation and Attitude Control of Multiple Free-Flying Spacecraft

Intheobservationslewingoflongbaselineinterferometersformedbymultiplefree-e yingspacecraftinformation, it is required to rotate the entire formation about a given axis and to synchronize individual spacecraft rotation with formation rotation. Using a particle model for spacecraft formation dynamics and a rigid-body model for spacecraft attitude dynamics, control laws are derived for this mode of operation in the absence of a gravitational e eld and disturbances. A simplie ed control law suitablefor implementation isalso obtained. It is shown thatunder mild conditionstheformation alignmenterrordecaystozeroexponentiallywith time. Computersimulationstudies are made for a free-e ying spacecraft triad in a triangular formation. The results show that the developed control laws are effective in synchronized formation rotation.
Bayesian Nonexhaustive Learning for Online Discovery and Modeling of Emerging Classes

We present a framework for online inference in the presence of a nonexhaustively defined set of classes that incorporates supervised classification with class discovery and modeling. A Dirichlet process prior (DPP) model defined over class distributions ensures that both known and unknown class distributions originate according to a common base distribution. In an attempt to automatically discover potentially interesting class formations, the prior model is coupled with a suitably chosen data model, and sequential Monte Carlo sampling is used to perform online inference. Our research is driven by a biodetection application, where a new class of pathogen may suddenly appear, and the rapid increase in the number of samples originating from this class indicates the onset of an outbreak.
Investment Decisions of Nonprofit Firms: Evidence from Hospitals

This paper examines investment choices of nonprofit hospitals. It tests how shocks to cash flows caused by the performance of the hospitals’ financial assets affect hospital expenditures. Capital expenditures increase, on average, by 10 to 28 cents for every dollar received from financial assets. The sensitivity is similar to that found earlier for shareholder-owned corporations. Executive compensation, other salaries, and perks do not respond significantly to cash flow shocks. Hospitals with an apparent tendency to overspend on medical procedures do not exhibit higher investment-cash flow sensitivities. The sensitivities are higher for hospitals that appear financially constrained
Effective-range corrections to the proton-proton fusion rate

Abstract Proton-proton fusion is considered in the effective field theory of Kaplan, Savage and Wise. Coulomb effects are included systematically in a non-perturbative way. Including the dimension-eight derivative coupling which determines the effective ranges of the scattering amplitudes, next-to-leading order corrections to the fusion rate are calculated. When the renormalization mass is well above the characteristic energies of the system, this contribution gives a rate which is eight percent below the standard value. The difference can be due to an unknown counterterm which comes in at this order.