cssi/SciSciGPT-SciSciNet huggingface dataset:
Multimer Radical Ions and Electron/Hole Localization in Polyatomic Molecular Liquids: A Critical Review

While ionization of some polyatomic molecular liquids (such as water and aliphatic alcohols) yields so-called "solvated electrons" in which the excess electron density is localized in the interstices between the solvent molecules, most organic and inorganic liquids yield radical anions and cations in which the electron and spin densities reside on the solvent molecule or, more commonly, a group of such molecules. The resulting multimer ions have many unusual properties, such as high rates of diffusive hopping. The "solvated electron" can be regarded as a variant of a multimer radical anion in which the charge, while perturbing the solvent molecules, mainly resides in the space between these molecules. We give several examples of less known modes for electron localization in liquids that yield multimer radical anions (such as C6F6, benzene, acetonitrile, carbon disulfide and dioxide, etc.) and holes localization in liquids that yield multimer radical cations (such as cycloalkanes). Current understanding of the reaction properties for these high-mobility solvent radical anions and cations is discussed.
Synthesis of internal fluorinated alkenes via facile aryloxylation of substituted phenols with aryl trifluorovinyl ethers.

Nucleophilic addition–elimination of ortho- or para-substituted phenols to aryl trifluorovinyl ethers (TFVEs) in N,N-dimethylformamide was studied. Using sodium hydride as a base afforded vinyl substitution products R–Ar–O–CFCF–O–Ar–R′, where R or R′ = H, Br, OMe, tert-Bu, or Ph. The vinyl substitution products produced mixtures of (Z)/(E)-isomers and this isomer ratio was influenced by substitution with more sterically encumbered phenol nucleophiles. Reactions using caesium carbonate afforded addition products R–Ar–O–CHFCF2–O–Ar–R′ whereas upon dehydrofluorination using sodium hydride produced vinyl substitution products. The preparation of vinyl substituted and addition products proceeded in overall good isolated yields and were elucidated using 1H and 19F NMR, GC-MS, and X-ray analysis. Vinyl substituted products were inert to UV light and chemical reactivity using common polymerization promoters. Thermal activation of the (Z)/(E)-fluoroolefin (-CFCF-) was observed at an onset of 310 °C in nitrogen using differential scanning calorimetry (DSC) producing insoluble network material. The synthesis, characterization, and mechanism for stereoselectivity are discussed.
Planet Formation with Migration

In the core-accretion model, gas-giant planets form solid cores that then accrete gaseous envelopes. Tidal interactions with disk gas cause a core to undergo inward type I migration in 104-105 yr. Cores must form faster than this to survive. Giant planets clear a gap in the disk and undergo inward type II migration in <106 yr if observed disk accretion rates apply to the disk as a whole. Type II migration times exceed typical disk lifetimes if viscous accretion occurs mainly in the surface layers of disks. Low turbulent viscosities near the midplane may allow planetesimals to form by coagulation of dust grains. The radius r of such planetesimals is unknown. If r < 0.5 km, the core formation time is shorter than the type I migration timescale, and cores will survive. Migration is substantial in most cases, leading to a wide range of planetary orbits, consistent with the observed variety of extrasolar systems. When r ~ 100 m and the midplane α ~ 3 × 10-5, giant planets similar to those in the solar system can form.
Boundary S-matrix of the O(N)-symmetric non-linear sigma model

Abstract We conjecture that the O( N )-symmetric non-linear sigma model (with N ⩾3) in the semi-infinite (1+1)-dimensional space is “integrable” with respect to the “free” and the “fixed” boundary conditions. We then derive, for both cases, the boundary S -matrix for the reflection of massive particles of this model off the boundary at x = 0.
The Evolution of the global stellar mass density at 0 < z < 3

The buildup of stellar mass in galaxies is the consequence of their past star formation and merging histories. Here we report measurements of rest-frame optical light and calculations of stellar mass at high redshift based on an infrared-selected sample of galaxies from the Hubble Deep Field-North. The bright envelope of rest-frame B-band galaxy luminosities is similar in the range 0 < z < 3, and the comoving luminosity density is constant to within a factor of 3 over that redshift range. However, galaxies at higher redshifts are bluer, and stellar population modeling indicates that they had significantly lower mass-to-light ratios than those of present-day L* galaxies. This leads to a global stellar mass density, Ω* , that rises with time from z = 3 to the present. This measurement essentially traces the integral of the cosmic star formation history that has been the subject of previous investigations. Between 50% and 75% of the present-day stellar mass density had formed by z ~ 1, but at z ≈ 2.7 we find that only 3%-14% of today's stars were present. This increase in Ω* with time is broadly consistent with observations of the evolving global star formation rate, once dust extinction is taken into account, but is steeper at 1 < z < 3 than predicted by some recent semianalytic models of galaxy formation. The observations appear to be inconsistent with scenarios in which the bulk of stars in present-day galactic spheroids formed at z 2.
Early Intervention for Symptomatic Youth at Risk for Bipolar Disorder: A Randomized Trial of Family-Focused Therapy

Objective Depression and brief periods of (hypo)mania are linked to an increased risk of progression to bipolar I or II disorder (BD) in children of bipolar parents. This randomized trial examined the effects of a 4-month family-focused therapy (FFT) program on the 1-year course of mood symptoms in youth at high familial risk for BD, and explored its comparative benefits among youth in families with high versus low expressed emotion (EE). Method Participants were 40 youth (mean 12.3±2.8 years, range 9–17) with BD not otherwise specified, major depressive disorder, or cyclothymic disorder who had a first-degree relative with BD I or II and active mood symptoms (Young Mania Rating Scale [YMRS]>11 or Child Depression Rating Scale>29). Participants were randomly allocated to FFT–High Risk version (FFT-HR; 12 sessions of psychoeducation and training in communication and problem-solving skills) or an education control (EC; 1–2 family sessions). Results Youth in FFT-HR had more rapid recovery from their initial mood symptoms (hazard ratio=2.69, p = .047), more weeks in remission, and a more favorable trajectory of YMRS scores over 1 year than youth in EC. The magnitude of treatment effect was greater among youth in high-EE (versus low-EE) families. Conclusions FFT-HR may hasten and help sustain recovery from mood symptoms among youth at high risk for BD. Longer follow-up will be necessary to determine whether early family intervention has downstream effects that contribute to the delay or prevention of full manic episodes in vulnerable youth. Clinical trial registration information—Early Family-Focused Treatment for Youth at Risk for Bipolar Disorder; http://www.clinicaltrials.gov/; NCT00943085.
Improved Pyrite Rejection by Chemically-Modified Fine Coal Flotation†

Abstract Improved pyrite rejection during fine coal flotation can be achieved by chemical pretreatment of the coal prior to flotation. The process involves conditioning the suspension with potassium monopersulfate or other peroxy compounds followed by conventional flotation. The ambient-temperature treatment seems to improve the hydrophobic character of certain low-rank coals as is evident from induction time measurements and bench-scale flotation experiments. In addition, the chemical pretreatment leads to an improvement in ash rejection and to enhanced depression of pyrite.
Concurrent Subspace Optimization Using Design Variable Sharing in a Distributed Computing Environment

This paper reviews recent implementation advances and modifications in the continued development of a Concurrent Subspace Op timization (CSSO) algorithm for Multidisciplinary Design Optimization (MDO) The CSSO MDO algorithm implemented in this research incor porates a Coordination Procedure of System Approximation (CP-SA) for design updates This study also details the use of a new discipline based decomposition strategy which provides for design variable sharing across discipline design regimes (i e subspaces) A graphical user interface is developed which provides for menu driven execution of MDO algorithms and results display this new programming environment highlights the modularity of the CSSO algorithm The algorithm is implemented in a distributed computing environment using the graphical user interface providing for truly concurrent discipline design Implementation studies introduce two new multidisciplinary design test problems the optimal design of a high performance, low cost structural system and...
What can solid state NMR contribute to our understanding of protein folding

Complete understanding of the folding process that connects a structurally disordered state of a protein to an ordered, biochemically functional state requires detailed characterization of intermediate structural states with high resolution and site specificity. While the intrinsically inhomogeneous and dynamic nature of unfolded and partially folded states limits the efficacy of traditional X-ray diffraction and solution NMR in structural studies, solid state NMR methods applied to frozen solutions can circumvent the complications due to molecular motions and conformational exchange encountered in unfolded and partially folded states. Moreover, solid state NMR methods can provide both qualitative and quantitative structural information at the site-specific level, even in the presence of structural inhomogeneity. This article reviews relevant solid state NMR methods and their initial applications to protein folding studies. Using either chemical denaturation to prepare unfolded states at equilibrium or a rapid freezing apparatus to trap non-equilibrium, transient structural states on a sub-millisecond time scale, recent results demonstrate that solid state NMR can contribute essential information about folding processes that is not available from more familiar biophysical methods.
Serendipitous Discovery of a Cataclysmic Variable in the Globular Cluster NGC 6624

Despite indications that classical cataclysmic variable (CV) stars are rare in globular clusters in general, and in the cluster NGC 6624 in particular, we have serendipitously discovered such a star ~6'' from the cluster center. A Hubble Space Telescope spectrum of the m ~ 22 object shows strong, broad emission lines typical of numerous field CVs, and the inferred optical and UV luminosity are also similar. Our accidental observation also provides the first high-quality ultraviolet spectrum of a globular cluster CV. That we have detected such an object in an observation that includes just a few percent of the central area of the cluster may indicate that cluster CVs are more common than previously thought, at least near the core.
Direct Preparation of Arylmanganese Bromides Using Active Manganese

Abstract Arylmanganese compounds were easily prepared via the direct oxidative addition of Rieke manganese to aryl bromides under mild conditions. The resulting organomanganese reagents undergo coupling reaction with acid chlorides to give the corresponding ketones in moderate yields.
Extension of Chronological Calculus for dynamical systems on manifolds

Abstract We propose an extension of the Chronological Calculus, developed by Agrachev and Gamkrelidze for the case of C ∞ -smooth dynamical systems on finite-dimensional C ∞ -smooth manifolds, to the case of C m -smooth dynamical systems and infinite-dimensional C m -manifolds. Due to a relaxation in the underlying structure of the calculus, this extension provides a powerful computational tool without recourse to the theory of calculus in Frechet spaces required by the classical Chronological Calculus. In addition, this extension accounts for flows of vector fields which are merely measurable in time. To demonstrate the utility of this extension, we prove a variant of Chow–Rashevskii theorem for infinite-dimensional manifolds.
Addressing the homeland security problem: A collaborative decision‐making framework

A majority of critical decisions requires collaborative efforts among analysts to build situation awareness. Teams of decision makers frequently have to react to incoming facts and developing events in a timely fashion such that the consequences of the decisions made largely have a positive impact on a developing situation. This problem is further exacerbated due to the multitude of agencies involved in the decision-making process. Thus, the decision-making processes faced by the intelligence agencies are characterized by group deliberations that are highly ill structured and yield limited analytical tractability. In this context, a collaborative approach to providing cognitive support to decision makers using a connectionist modeling approach is proposed. The connectionist modeling of such decision scenarios offers several unique and significant advantages in developing systems to support collaborative discussions. Several inference rules for augmenting the argument network and to capture implicit notions in arguments are proposed. We further explore the effects of incorporating notions of information source reliability within arguments and the effects thereof.
The Hubbard chain: Lieb–Wu equations and norm of the eigenfunctions

Abstract We conjecture that the square of the norm of the Hubbard wave function is proportional to the determinant of a matrix, which is obtained by linearization of the Lieb–Wu equations around a solution. This means that in the vicinity of a solution the Lieb–Wu equations are non-degenerate, if the corresponding wave function is non-zero. We further derive an action that generates the Lieb–Wu equations and express our determinant formula for the square of the norm in terms of the Hessian determinant of this action.
Cosmic variance in the great observatories origins deep survey

Cosmic variance is the uncertainty in observational estimates of the volume density of extragalactic objects such as galaxies or quasars arising from the underlying large-scale density fluctuations. This is often a significant source of uncertainty, especially in deep galaxy surveys, which tend to cover relatively small areas. We present estimates of the relative cosmic variance for one-point statistics (i.e., number densities) for typical scales and volumes sampled by the Great Observatories Origins Deep Survey (GOODS). We use two approaches: (1) For objects with a known two-point correlation function that is well approximated by a power law, one can use the standard analytic formalism to calculate the cosmic variance (in excess of shot noise). We use this approach to estimate the cosmic variance for several populations that are being studied in the GOODS program (extremely red objects [EROs] at z ~ 1 and Lyman break galaxies [LBGs] at z ~ 3 and z ~ 4) using clustering information for similar populations in the literature. (2) For populations with unknown clustering, one can use predictions from cold dark matter theory to obtain a rough estimate of the variance as a function of number density. We present a convenient plot that allows one to use this approach to read off the cosmic variance for a population with a known mean redshift and estimated number density. We conclude that for the volumes sampled by GOODS, cosmic variance is a significant source of uncertainty for strongly clustered objects (~40%-60% for EROs) and less serious for less clustered objects (~10%-20% for LBGs).
Polynomial regression with automated degree: A function approximator for autonomous agents

In order for an autonomous agent to behave robustly in a variety of environments, it must have the ability to learn approximations to many different functions. The function approximator used by such an agent is subject to a number of constraints that may not apply in a traditional supervised learning setting. Many different function approximators exist and are appropriate for different problems. This paper proposes a set of criteria for function approximators for autonomous agents. Additionally, for those problems on which polynomial regression is a candidate technique, the paper presents an enhancement that meets these criteria. In particular, using polynomial regression typically requires a manual choice of the polynomial's degree, trading off between function accuracy and computational and memory efficiency. Polynomial Regression with Automated Degree (PRAD) is a novel function approximation method that uses training data to automatically identify an appropriate degree for the polynomial. PRAD is fully implemented. Empirical tests demonstrate its ability to efficiently and accurately approximate both a wide variety of synthetic functions and real-world data gathered by a mobile robot.
Novel Polarization Enhanced Ohmic Contacts to n‐Type GaN

Utilizing a thin n-type Al x Ga 1-x N layer on top of n-type GaN, the metal-semiconductor contact resistance can be decreased drastically compared to bulk n-type GaN. Specific contact resistances as low as 8.5 x 10 -5 Q cm 2 have been achieved without high temperature annealing. The design of this novel contact is based on polarization fields in the thin Al x Ga 1-x N layer.
Effect of Hot Baryons on the Weak-Lensing Shear Power Spectrum

We investigate the impact of the intracluster medium on the weak-lensing shear power spectrum (PS). Using a halo model we find that, compared to the dark matter-only case, baryonic pressure leads to a suppression of the shear PS on the order of a few percent or more for l 1000. Cooling/cooled baryons and the intergalactic medium can further alter the shear PS. Therefore, the interpretation of future precision weak-lensing data at high multipoles must take into account the effects of baryons.
The Learning Curve for Flank Percutaneous Nephrolithotomy for Kidney Calculi: A Single Surgeon's Experience.

Purpose: Percutaneous nephrolithotomy (PCNL) is conventionally conducted in the prone position. However, the prone position increases anesthesia-related morbidity and position changes lengthen the operation time. We report perioperative outcomes and the learning curve for flank PCNL on the basis of a single surgeon’s experience. Materials and Methods: This study investigated 53 cases of flank PCNL performed for renal stones at our institution from April 2008 to September 2010. We compared mean operative time, stone-free rate, drop in hemoglobin level, length of hospital stay, complications, and need for additional procedures after the surgery. The 53 cases were divided into three groups by case number to compare therapeutic effect, stability, and the learning curve for flank position PCNL. Results: The mean operation time for the 53 patients was 97.3±43.1 minutes. The mean operation time gradually decreased as the surgeon accumulated experience. From the 36th case, the mean operation time showed a statistically significant decrease to 72.2± 24.1 minutes (p=0.003). The overall stone-free rate was 64.2% for all procedures (range, 61.1-76.5%). There were no significant differences in the drop in hemoglobin level, stone-free rate, re-treatment, hospital stay, or complication rate. There was no injury to the bowel or renal vessels, and no other major complications occurred. Conclusions: Flank PCNL can be used to remove renal stones effectively while overcoming the disadvantages of the existing prone position PCNL. After 36 cases, the learning curve showed acquisition of surgical competence. The clinical experience reported here suggests that flank PCNL is a safe and feasible technique.
An animal model for measurement of protein metabolism in the skin

Background. A suitable in vivo approach with which to quantify skin protein metabolism has not been found, and consequently no information exists relating protein synthesis to protein breakdown in the fasted state. Methods. Stable isotope-labeled phenylalanine was infused into five fasted rabbits, and amino acid and protein kinetics were calculated from a three-compartment model with the rabbit ear used as an arteriovenous balance mode. Results were compared with the more traditional but limited direct incorporation technique to measure synthesis. Results. The model-derived skin protein synthesis rate was 0.34%/hr±0.04%/hr, which was almost identical to the value of 0.30%/hr±0.01%/hr determined by the direct incorporation method. The model-derived skin protein breakdown rate was only slightly higher than the synthesis rate, meaning protein balance was generally maintained in the fasted state because of the efficient reuse of amino acids from protein breakdown. Conclusions. The newly described rabbit ear model is a reliable approach to the determination of the amino acid and protein kinetics in the skin in vivo. Efficient reuse of amino acids released from proteolysis explains the maintenance of skin integrity during brief fasting.
Pattern formation with a compartmental lateral inhibition system

We propose a compartmental lateral inhibition system that generates contrasting patterns of gene expression between neighboring compartments. The system consists of a set of compartments interconnected by channels. Each compartment contains a colony of cells that produce diffusible molecules to be detected by the neighboring colony, and each cell is equipped with an inhibitory circuit that reduces its production when the detected signal is stronger. We develop a technique to analyze the steady-state patterns emerging from this lateral inhibition system and apply it to a specific implementation. The analysis shows that the proposed system indeed exhibits contrasting patterns within realistic parameter ranges.
The symmetries of solitons

In this article we will retrace one of the great mathematical adventures of this century—the discovery of the soliton and the gradual explanation of its remarkable properties in terms of hidden symmetries. We will take an historical approach, starting with a famous numerical experiment carried out by Fermi, Pasta, and Ulam on one of the first electronic computers, and with Zabusky and Kruskal’s insightful explanation of the surprising results of that experiment (and of a follow-up experiment of their own) in terms of a new concept they called “solitons”. Solitons however raised even more questions than they answered. In particular, the evolution equations that govern solitons were found to be Hamiltonian and have infinitely many conserved quantities, pointing to the existence of many non-obvious symmetries. We will cover next the elegant approach to solitons in terms of the Inverse Scattering Transform and Lax Pairs, and finally explain how those ideas led step-by-step to the discovery that Loop Groups, acting by “Dressing Transformations”, give a conceptually satisfying explanation of the secret soliton symmetries.
On optical detection of densely labeled synapses in neuropil and mapping connectivity with combinatorially multiplexed fluorescent synaptic markers

We propose a new method for mapping neural connectivity optically, by utilizing Cre/Lox system Brainbow to tag synapses of different neurons with random mixtures of different fluorophores, such as GFP, YFP, etc., and then detecting patterns of fluorophores at different synapses using light microscopy (LM). Such patterns will immediately report the pre- and post-synaptic cells at each synaptic connection, without tracing neural projections from individual synapses to corresponding cell bodies. We simulate fluorescence from a population of densely labeled synapses in a block of hippocampal neuropil, completely reconstructed from electron microscopy data, and show that high-end LM is able to detect such patterns with over 95% accuracy. We conclude, therefore, that with the described approach neural connectivity in macroscopically large neural circuits can be mapped with great accuracy, in scalable manner, using fast optical tools, and straightforward image processing. Relying on an electron microscopy dataset, we also derive and explicitly enumerate the conditions that should be met to allow synaptic connectivity studies with high-resolution optical tools.
Unbiased Rotational Moves for Rigid-Body Dynamics

We introduce an unbiased protocol for performing rotational moves in rigid-body dynamics simulations. This approach—based on the analytic solution for the rotational equations of motion for an orthogonal coordinate system at constant angular velocity—removes deficiencies that have been largely ignored in Brownian dynamics simulations, namely errors for finite rotations that result from applying the noncommuting rotational matrices in an arbitrary order. Our algorithm should thus replace standard approaches to rotate local coordinate frames in Langevin and Brownian dynamics simulations.
Distinguishing Pelvic Phleboliths From Distal Ureteral Stones on Routine Unenhanced Helical CT: Is There a Radiolucent Center?

Jeffrey Traubici1 Jeffrey D. Neitlich Robert C. Smith OBJECTIVE. On radiographs ofthe abdomen and pelvis, phleboliths often have a characteristic radiolucent center that helps to distinguish them from ureteral stones. On unenhanced CT, the distinction between pelvic phleboliths and distal ureteral stones can be problematic. The objective of this study was to compare the appearance of phleboliths on routine clinical CT studies with their appearance on radiography and to determine if the radiolucent center seen on radiographs is revealed on CT. SUBJECTS AND METHODS. During a 3-month interval, we identified 50 patients with acute flank pain who underwent both unenhanced CT and abdominal radiography. Patients with a radiograph of the pelvis and an unenhanced CT scan obtained within 1 month of each other were included. CT was performed with a collimation of 5 mm and a pitch of 1. Each phlebolith was examined using soft-tissue and bone settings and was also retrospectively pixel mapped. RESULTS. Seventy-nine (66%) of 120 phleboliths revealed radiolucent centers on abdominal radiography. On CT, 1 19 (99%) of 120 phleboliths failed to reveal a low-attenuation center on both visual inspection and pixel mapping. CONCLUSION. Pelvic phleboliths were shown to lack a radiolucent center on routine clinical CT examinations despite their appearance on radiography. A radiolucent center therefore cannot be used to differentiate phleboliths from distal ureteral stones on unenhanced CT in patients with acute flank pain and suspected ureteral obstruction.
Implications of agricultural trade liberalization for the developing countries

Abstract The developing countries as a group could expect to experience only small welfare gains if they chose not to actively participate in agricultural trade liberalization and relied solely on the benefits of partial liberalization in the OECD countries. Participation along the lines of the Dunkel package, with the developing countries reducing positive assistance by less than the developed countries, would yield gains of the order of US $20 billion. More comprehensive participation in trade liberalization involving reductions of both positive and negative protection would almost triple these welfare gains. While some developing countries do not gain from trade liberalization even with full participation, the number of such countries and the magnitude of their losses are greatly reduced.
Prospects for Hypercharged Anomaly Mediated SUSY Breaking at the LHC

We investigate the phenomenological consequences of string models wherein the MSSM resides on a D-brane, and the hypercharge gaugino mass is generated in a geometrically separated hidden sector. This hypercharged anomaly-mediated SUSY breaking (HCAMSB) model naturally solves the tachyonic slepton mass problem endemic to pure AMSB scenarios. In HCAMSB, one obtains a mass ordering M1>μ>M2 with split left- and right- scalars, whereas in mAMSB models, one obtains μ>M1>M2 with nearly degenerate left- and right- scalars. We compute the allowed parameter space and expected superparticle mass spectrum in the HCAMSB model. For low values of the HC and AMSB mixing parameter α, the spectra is characterized by light left-sleptons, while the spectra for large α is characterized by light top- and bottom- squarks. We map out the approximate reach of LHC for HCAMSB, and find that with 100 fb−1 of integrated luminosity, a gravitino mass of ~ 115 (105) TeV can be probed for low (high) values of α, corresponding to a gluino mass reach of ~ 2.4 (2.2) TeV. Both cases contain — as is typical in AMSB models — long lived charginos that should yield visible highly ionizing tracks in the LHC detector. Also, in the lower tan β range, HCAMSB models give rise to reconstructable Z → l candidates in SUSY cascade decay events, while mAMSB models should do so only rarely.
From light nuclei to nuclear matter the role of relativity

The success of non-relativistic quantum dynamics in accounting for the binding energies and spectra of light nuclei with masses up to A=10 raises the question whether the same dynamics applied to infinite nuclear matter agrees with the empirical saturation properties of large nuclei. The simple unambiguous relation between few-nucleon and many-nucleon Hamiltonians is directly related to the Galilean covariance of nonrelativistic dynamics. Relations between the irreducible unitary representations of the Galilei and Poincare groups indicate that the "nonrelativistic" nuclear Hamiltonians may provide sufficiently accurate approximations to Poincare invariant mass operators. In relativistic nuclear dynamics based on suitable Lagrangeans the intrinsic nucleon parity is an explicit, dynamically relevant, degree of freedom and the emphasis is on properties of nuclear matter. The success of this approach suggests the question how it might account for the spectral properties of light nuclei.
Synthesis of trans-2-(1-aryl-1-methylethyl)cyclohexylamines.

As a first example of opening a secondary aziridine with a tertiary carbanion, the title amines (3a−c, aryl = phenyl, 4-tert-butylphenyl, 2-naphthyl) were synthesized by opening N-(diphenylphosphinoyl)-7-azabicyclo[4.1.0]heptane, aziridine 1, with the corresponding α-potassium isopropylarenes, followed by hydrolysis of the resulting phosphinamides 2a−c.
Analytical Versus Neural Real-Time Simulation of a Photovoltaic Generator Based on a DC–DC Converter

This paper presents a simulator of a photovoltaic (PV) field where the current-voltage characteristic is obtained either with a fully analytical model or with a numerical model based on a growing neural gas (GNG) network. The power stage is obtained with a dc-dc buck converter driven by the current-voltage-irradiance-temperature relation of the PV array. The improvements introduced here, with respect to previous works, are the following: 1) the mathematical model is given as a continuous surface in the irradiance domain; 2) a relation between temperature and irradiance is obtained by least square regression method; 3) the thermal constant of the PV field is introduced; and 4) an experimental prototype of higher rating has been devised and constructed. For both approaches, a more performing control technique of the converter has been used. Finally, a PV simulator prototype is experimentally tested. Some criteria for a suitable choice between the proposed approaches and the benefits obtainable by the use of the GNG are put into evidence.
Dose distribution in total skin electron beam irradiation using the six-field technique

Total skin low energy electron beam irradiation is used to treat superficially widespread skin lesions such as cutaneous T-cell lymphoma. Total skin irradiation involves delivering an adequate dose at a depth of 0.25 to 1.0 cm, while sparing underlying tissue. The dose distributions obtained when using a modified Stanford six-field technique depend upon the beam energy, the beam angle, the diameter and shape of the body part, and other variables. The dose distribution uniformity of six pairs of angulated electron beams has been studied as a function of beam energy, the gantry angle, +/- theta, above and below the horizontal and the diameter of a cylindrical polystyrene phantom. Depth doses and dose uniformity for single and multiple fields have been measured as a function of beam energy, phantom diameter and position.
Aza Diels-Alder reactions in aqueous solution: cyclocondensation of dienes with simple iminium salts generated under Mannich conditions

Cycloadditions de sels d'iminium obtenus par reaction de Mannich d'amines primaires avec des composes dieniques conjugues: obtention de tetrahydropyridines, d'aza-2bicyclo [2.2.2] octenes-5, d'aza-2bicyclo [2.2.1], heptenes-5; application a la synthese d'hexahydro indolizines et quinolizines par cycloaddition intramoleculaire des alcadienylamines correspondantes et a la synthese de benzyl-1 methyl-2 octahydro quinoleine a partir de benzylamine et de decadiene-6,8al
Deuterated Ammonia in Galactic Protostellar Cores

We report on a survey of NH2D toward protostellar cores in low-mass star formation and quiescent regions in the Galaxy. Twenty-three out of thirty-two observed sources have significant (5 σ) NH2D emission. Ion-molecule chemistry, which preferentially enhances deuterium in molecules above the local interstellar medium value value of 1.6 × 10-5, sufficiently explains these abundances. NH2D/NH3 ratios toward class 0 sources yields information about the "fossil remnants" from the era prior to the onset of core collapse and star formation. We compare our observations with predictions of gas-phase chemical networks.
Computer measurement and evaluation: artistry, or science?

Effort invested in computer measurement and evaluation is clearly increasing, but the results of this increasing investment may be unfortunate. The undeniable value of the results and the enthusiasm of participants may be leading to unrealizable expectations. The present artistry needs to be converted into a science for achieving a solid future; the most fruitful direction may be the synthesis of individual, empirical discoveries combined with testing hypotheses about performance relationships.
SPICE Lumped Circuit Subcell Model for the Discontinuous Galerkin Finite-Element Time-Domain Method

A SPICE lumped circuit subcell model is formulated within the discontinuous Galerkin finite-element time-domain (DGFETD) discretization of Maxwell's equations. A fourth-order exponential time difference (ETD) algorithm is used for circuits that lead to stiff systems. The ETD method reduces to a standard fourth-order Runge-Kutta (RK4) time-integration for nonstiff regions. A number of test cases, including a microstrip transmission line terminated with general RLC networks, load arrays, and a diode detector are presented for the validation of the proposed hybrid DGFETD/SPICE solution method.
Investigation of supersonic jet plumes using an improved two-equation turbulence model

Supersonic jet plumes were studied using a two-equation turbulence model employing corrections for compressible dissipation and pressure-dilatation. A space-marching procedure based on an upwind numerical scheme was used to solve the governing equations and turbulence transport equations. The computed results indicate that two-equation models employing corrections for compressible dissipation and pressure-dilatation yield improved agreement with the experimental data. In addition, the numerical study demonstrates that the computed results are sensitive to the effect of grid refinement and insensitive to the type of velocity profiles used at the inflow boundary for the cases considered in the present study.
Atmospheric dynamics of Earth-like tidally locked aquaplanets

We present simulations of atmospheres of Earth-like aquaplanets that are tidally locked to their star, that is, planets whose orbital period is equal to the rotation period about their spin axis, so that one side always faces the star and the other side is always dark. Such simulations are of interest in the study of tidally locked terrestrial exoplanets and as illustrations of how planetary rotation and the insolation distribution shape climate. As extreme cases illustrating the effects of slow and rapid rotation, we consider planets with rotation periods equal to one current Earth year and one current Earth day. The dynamics responsible for the surface climate (e.g., winds, temperature, precipitation) and the general circulation of the atmosphere are discussed in light of existing theories of atmospheric circulations. For example, as expected from the increasing importance of Coriolis accelerations relative to inertial accelerations as the rotation rate increases, the winds are approximately isotropic and divergent at leading order in the slowly rotating atmosphere but are predominantly zonal and rotational in the rapidly rotating atmosphere. Free-atmospheric horizontal temperature variations in the slowly rotating atmosphere are generally weaker than in the rapidly rotating atmosphere. Interestingly, the surface temperature on the night side of the planets does not fall below ∼240 K in either the rapidly or slowly rotating atmosphere; that is, heat transport from the day side to the night side of the planets efficiently reduces temperature contrasts in either case. Rotational waves and eddies shape the distribution of winds, temperature, and precipitation in the rapidly rotating atmosphere; in the slowly rotating atmosphere, these distributions are controlled by simpler divergent circulations. Both the slowly and rapidly rotating atmospheres exhibit equatorial superrotation. Systematic variation of the planetary rotation rate shows that the equatorial superrotation varies non-monotonically with rotation rate, whereas the surface temperature contrast between the day side and the night side does not vary strongly with changes in rotation rate.
The sequencing of union contract negotiations

In this paper we explore the determination of the sequencing of wage bargains in an institutional structure consisting of a single firm employing two unions, under two alternative assumptions about the nature of feasible contracts. If contingent contracts are prohibitively costly, we find that the unions prefer to lead in the negotiations process if the labor inputs are substitutes and follow if they are complements, while the firm is indifferent. If contingent contracts are permitted, both unions prefer to lead, while the firm prefers to negotiate first with the weaker union.
COMPUTATIONAL GEOMETRY COLUMN 39

The resolution of a decades-old open problem is described: polygonal chains cannot lock in the plane.
Digital control of repetitive errors in disk drive systems

Tracking errors in disk drive systems have a significant repetitive component that is not explicitly taken into account in conventional servo controllers. A modified prototype repetitive controller is applied as a plug-in module to a Winchester disk drive with a preexisting analog feedback controller to demonstrate its efficacy in the reduction of this periodic component. A review of the Winchester disk drive system is included. >
Cone-based electrical resistivity tomography

Determining the 3D spatial distribution of subsurface propertiesisachallenging,butcritical,partofmanagingthecleanupof contaminated sites. We have developed a minimally invasive technology that can provide information about the 3D distribution of electrical conductivity. The technique, cone-based electrical resistivity tomography C-bert, integrates resistivity tomography with cone-penetration testing. Permanent current electrodes are emplaced in the subsurface and used to inject currentintothesubsurfaceregionofinterest.Theresultantpotential fields are measured using a surface reference electrode and an electrodemountedonaconepenetrometer.Thestandardsuiteof conepenetrationmeasurements,includinghigh-resolutionresistivitylogs,arealsoobtainedandareanintegralpartoftheC-bert method.C-bertdataareinvertedusinganinexactGauss-Newton algorithm to produce a 3D electrical conductivity map.Amajor challenge with the inversion is the large local perturbation around the measurement location, due to the highly conductive cone.As the cone is small with respect to the total model space, explicit modeling of the cone is cost prohibitive.We have developedarapidmethodforsolvingtheforwardmodelwhichusesiteratively determined boundary conditions IDBC. This allows us to generate a computationally feasible, preinversion correctionfortheconeperturbation.WeassessedC-bertbyperforming a field test to image the conductivity structure of the Kidd 2 site nearVancouver,BritishColumbia.Atotalofninepermanentcurrent electrodes were emplaced and five C-bert data sets were obtained, resulting in 6516 data points.These data were inverted to obtain a 3D conductivity image of the subsurface. Furthermore, we demonstrated, using a synthetic experiment, that C-bert can yield high quality electrical conductivity images in challenging field situations. We conclude that C-bert is a promising new imagingtechnique.
Stable levitation and alignment of compact objects by Casimir spring forces.

We investigate a stable Casimir force configuration consisting of an object contained inside a spherical or spheroidal cavity filled with a dielectric medium. The spring constant for displacements from the center of the cavity and the dependence of the energy on the relative orientations of the inner object and the cavity walls are computed. We find that the stability of the force equilibrium---unlike the direction of the torque---can be predicted based on the sign of the force between two slabs of the same material.
Low-power, parallel interface with continuous-time adaptive passive equalizer and crosstalk cancellation

This paper presents the low-power circuit techniques suitable for high-speed digital parallel interfaces each operating at over 10 Gbps. One potential application for such high-performance I/Os is the interface between the channel IC and the magnetic read head in future compact hard disk systems. First, a crosstalk cancellation technique using a novel data encoding scheme is introduced to suppress electromagnetic interference (EMI) generated by the adjacent parallel I/Os. This technique is implemented utilizing a novel 8-4-PAM signaling with a data look-ahead algorithm. The key circuit components in the high-speed interface transceiver including the receive sampler, the phase interpolator, and the transmitter output driver are described in detail. Designed in a 0.13-μm digital CMOS process, the transceiver consumes 310 mW per 10-Gps channel from a I-V supply based on simulation results. Next, a 20-Gbps continuous-time adaptive passive equalizer utilizing on-chip lumped RLC components is described. Passive equalizers offer the advantages of higher bandwidth and lower power consumption compared with conventional designs using active filter. A low-power, continuous-time servo loop is designed to automatically adjust the equalizer frequency response for the optimal gain compensation. The equalizer not only adapts to different channel characteristics, but also accommodates temperature and process variations. Implemented in a 0.25-μm, 1P6M BiCMOS process, the equalizer can compensate up to 20 dB of loss at 10 GHz while only consumes 32 mW from a 2.5-V supply.
On integration with respect to the q-Brownian motion

Abstract For a parameter 0 q 1 , we use the Jackson q -integral to define integration with respect to the so called q -Brownian motion. Our main results are the q -analogs of the L 2 -isometry and of the Ito formula for polynomial integrands. We also indicate how the L 2 -isometry extends the integral to more general functions.
Time- and polarization-resolved optical spectroscopy of colloidal CdSe nanocrystal quantum dots in high magnetic fields.

In an effort to elucidate the spin (rather than charge) degrees of freedom in colloidal semiconductor nanocrystal quantum dots, we report on a series of static and time-resolved photoluminescence measurements of colloidal CdSe quantum dots in ultrahigh magnetic fields up to 45 T. At low temperatures (1.5-40 K), the steady-state photoluminescence (PL) develops a high degree of circular polarization with applied magnetic field, indicating the presence of spin-polarized excitons. Time-resolved PL studies reveal a marked decrease in radiative exciton lifetime with increasing magnetic field and temperature. Except for an initial burst of unpolarized PL immediately following photoexcitation, high-field time-resolved PL measurements reveal a constant degree of circular polarization throughout the entire exciton lifetime, even in the presence of pronounced exciton transfer via Forster energy transfer processes.
Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) is increasingly recognized as a treatable cause of gait disturbance, cognitive decline, and urinary incontinence in the aging population. The impact of treatment on both improved quality of life and decreased need for institutional care is potentially very great, and will only increase as the population ages. This article provides a state-of-the-art review of the presentation, diagnosis, surgical treatment, and clinical management of idiopathic normal pressure hydrocephalus (iNPH).
Efficient Parameter Estimation Techniques for Hysteresis Models

Actuators employing ferroelectric or ferromagnetic compounds are solid-state, efficient, and compact making them well-suited for aerospace, aeronautic, industrial and military applications. However, they also exhibit frequency, stress and thermally-dependent hysteresis and constitutive nonlinearities which must be incorporated in models for accurate device characterization and control design. A critical step in the use of these models is the estimation or re-estimation of parameters in a manner that is both efficient and robust. In this presentation, we discuss techniques to estimate densities in the homogenized energy model based on Galerkin expansions using physically motivated basis functions. The yields highly tractable optimization algorithms in which initial parameter estimates can be obtained from measured properties of the data. The efficiency and accuracy of the models and estimation algorithms are validated with experimental data.
Signal-adaptive decomposition of multicomponent signals

In this paper we present a new method for adaptively decomposing a multicomponent signal into its components. This method is based on fitting an autoregressive (AR) model to the short-time spectra of the signal. The AR parameters represent the coefficients of the linear predictive (LP) polynomial. The roots of this polynomial constitute a set of center frequencies and bandwidths that characterize the modes of the signal. The decomposition process is achieved by applying a time-varying filter bank to the original multicomponent signal. The characteristics of this filter bank are derived from a subset of the roots of the LP polynomial. We have developed a constraining algorithm to determine that subset based on the boundedness of the bandwidths, and the temporal continuity of the center frequencies of the components. We have applied the proposed decomposition method for the separation of the formants of speech signals.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
A convenient synthesis of β,γ-unsaturated ketones via allylation of Z-1-halo-1-alkenyl-1,3,2-dioxaborolane

Abstract A convenient, general synthesis of β,γ-unsaturated ketones via allylation of Z-1-halo-1-alkenyl-1,3,2-dioxaborolane has been developed. The reactivity under different conditions and the effect of an additive, HMPA, is elucidated. A representative procedure for the synthesis of 1-nonen-3-one is described.
Enantiospecific total synthesis of tryprostatin A

Abstract The 3-methyl-6-methoxyindole 3 was converted into tryprostatin A ( 1 ) via a regiospecific bromination process coupled with the Schollkopf chiral auxillary 7 to provide the 2-bromo-6-methoxy-tryptophan 8a as a key intermediate.