cssi/SciSciGPT-SciSciNet huggingface dataset:
Study of Phase-Matched Normal and Umklapp Third-Harmonic- Generation Processes in Cholesteric Liquid Crystals

Using the model of Oseen and de Vries, we show that phase matching of optical third-harmonic generation can be achieved in a cholesteric liquid crystal with the help of the lattice momentum. Many different collinear phase-matching conditions exist. In some cases, the phase-matched third harmonic is generated in the same direction as the fundamental, and in some other cases, it is generated in the opposite direction. In many other cases, phase-matched third-harmonic generation requires the simultaneous presence of fundamental waves propagating in opposite directions. Analogous to electron-electron interaction in a periodic lattice, these processes can be identified as coherent, normal, and umklapp third-harmonic-generation processes. Experiments using a mode-locked Nd laser as the fundamental source verify the existence of most of the predicted phase-matching conditions. Our results agree well with the theoretical predictions.
Knowledge Integration in OpenWorlds: Utilizing the Mathematics of Hierarchical Structure

Semantic Web services present a new challenge in distributed knowledge integration. Under the Simple Semantic Web Architecture and Protocol (SSWAP, http://sswap.info), Web resources publish information about their data and services in terms of OWL ontologies. With semantic tagging, the output of one service can drive the input of another, presenting the alluring prospect of machines autonomously assessing the suitability of Web resources for distributed workflows. Ontological reasoning under OWL greatly expands the potential for semantic Web service interoperability by guaranteeing the compatibility of resources using such techniques as inferencing, typing, and class subsumption. Formal methods for managing such structures are urgently needed. Recent advances in the mathematics of hierarchies can formalize the construction of synthetic hierarchies from unstructured information, identifying mutual subsumption architectures. Here we examine the problem space and describe the promise of mathematical order theory (formal concept analysis and lattice metrics) for advancing knowledge integration in open worlds.
THE ENVELOPE AND EMBEDDED DISK AROUND THE CLASS 0 PROTOSTAR L1157-mm: DUAL-WAVELENGTH INTERFEROMETRIC OBSERVATIONS AND MODELING

We present dual-wavelength observations and modeling of the nearly edge-on Class 0 young stellar object L1157-mm. Using the Combined Array for Research in Millimeter-wave Astronomy, a nearly spherical structure is seen from the circumstellar envelope at the size scale of 10{sup 2}-10{sup 3} AU in both 1 mm and 3 mm dust emission. Radiative transfer modeling is performed to compare data with theoretical envelope models, including a power-law envelope model and the Terebey-Shu-Cassen model. Bayesian inference is applied for parameter estimation and information criterion is used for model selection. The results prefer the power-law envelope model against the Terebey-Shu-Cassen model. In particular, for the power-law envelope model, a steep density profile with an index of {approx}2 is inferred. Moreover, the dust opacity spectral index {beta} is estimated to be {approx}0.9, implying that grain growth has started at L1157-mm. Also, the unresolved disk component is constrained to be {approx}<40 AU in radius and {approx}<4-25 M{sub Jup} in mass. However, the estimate of the embedded disk component relies on the assumed envelope model.
Total synthesis of (+)-amphidinolide A. Assembly of the fragments.

The structure elucidation of (+)-amphidinolide A, a cytotoxic macrolide, has been accomplished by employing a combination of total synthesis and NMR spectroscopic analysis. Amphidinolide A possesses two skipped 1,4-diene subunits which are accessible by ruthenium-catalyzed alkene−alkyne couplings. Previous total syntheses had revealed that the reported structure was incorrect; therefore, to incorporate maximum flexibility into the synthesis, with the ultimate goal of determining the correct structure, a highly convergent approach was chosen. Furthermore, liberal use was made of catalytic asymmetric transformations to set individual stereocenters. Three different strategies were envisioned for the end game, and due to the highly convergent nature of the synthesis, all three routes disconnect to the same three key intermediates, 5, 6, and 7. Diastereomers of 6 and 7 were easily prepared by modification of the synthetic routes to allow access to multiple diastereomers of 1 for structural determination.
Procrastination of Enjoyable Experiences

Abstract The tendency to procrastinate applies not only to aversive tasks but also to positive experiences with immediate benefits. The authors propose that models of time discounting can explain this behavior, and they test these predictions with field data and experiments. A multicity study shows that people with unlimited time windows delay visiting desirable landmarks; however, procrastination is reduced when the window of opportunity is constrained. Similarly, people procrastinate in redeeming gift certificates and gift cards with long deadlines more than those with short deadlines, resulting in overall lower redemption rates. These results run counter to participants' predictions and typical models of impulsive behavior.
Financial innovation and bank risk taking

Abstract In this paper we investigate the effect of one change in the financial sector, namely, the growing ease with which assets created by the banking sector can be sold to other investors. Of interest is whether the reduced cost of value communication and asset sales leads to higher levels of risky lending by the banking sector. Of equal interest is whether these same changes result in riskier banks, i.e., ones that are more vulnerable to instability and failure. The results suggest that the risky asset portfolio held by the banking sector unambiguously increases as a result of the innovations considered. A reduction in illiquidity increases the banking sector's willingness to provide risk capital for real sector investment. On the other hand, it does not imply that banks will become more risky. Rather, there exists a trade-off between external shock risk, which is alleviated by increased asset liquidity, and the risk taking by banks on the returns of their assets, which is encouraged by these market changes.
SIMULTANEOUS MULTIWAVELENGTH OBSERVATIONS OF MAGNETIC ACTIVITY IN ULTRACOOL DWARFS. IV. THE ACTIVE, YOUNG BINARY NLTT 33370 AB (= 2MASS J13142039+1320011)

We present multi-epoch simultaneous radio, optical, Hα, UV, and X-ray observations of the active, young, low-mass binary NLTT 33370 AB (blended spectral type M7e). This system is remarkable for its extreme levels of magnetic activity: it is the most radio-luminous ultracool dwarf (UCD) known, and here we show that it is also one of the most X-ray luminous UCDs known. We detect the system in all bands and find a complex phenomenology of both flaring and periodic variability. Analysis of the optical light curve reveals the simultaneous presence of two periodicities, 3.7859 ± 0.0001 and 3.7130 ± 0.0002 hr. While these differ by only ∼2%, studies of differential rotation in the UCD regime suggest that it cannot be responsible for the two signals. The system's radio emission consists of at least three components: rapid 100% polarized flares, bright emission modulating periodically in phase with the optical emission, and an additional periodic component that appears only in the 2013 observational campaign. We interpret the last of these as a gyrosynchrotron feature associated with large-scale magnetic fields and a cool, equatorial plasma torus. However, the persistent rapid flares at all rotational phases imply that small-scale magnetic loops are also present and reconnect nearly continuously.more » We present a spectral energy distribution of the blended system spanning more than 9 orders of magnitude in wavelength. The significant magnetism present in NLTT 33370 AB will affect its fundamental parameters, with the components' radii and temperatures potentially altered by ∼+20% and ∼–10%, respectively. Finally, we suggest spatially resolved observations that could clarify many aspects of this system's nature.« less
Bragg Scattering as a Probe of Atomic Wave Functions and Quantum Phase Transitions in Optical Lattices

We have observed Bragg scattering of photons from quantum degenerate $^{87}\mathrm{Rb}$ atoms in a three-dimensional optical lattice. Bragg scattered light directly probes the microscopic crystal structure and atomic wave function whose position and momentum width is Heisenberg limited. The spatial coherence of the wave function leads to revivals in the Bragg scattered light due to the atomic Talbot effect. The decay of revivals across the superfluid to Mott insulator transition indicates the loss of superfluid coherence.
HGTector: an automated method facilitating genome-wide discovery of putative horizontal gene transfers

First pass methods based on BLAST match are commonly used as an initial step to separate the different phylogenetic histories of genes in microbial genomes, and target putative horizontal gene transfer (HGT) events. This will continue to be necessary given the rapid growth of genomic data and the technical difficulties in conducting large-scale explicit phylogenetic analyses. However, these methods often produce misleading results due to their inability to resolve indirect phylogenetic links and their vulnerability to stochastic events. A new computational method of rapid, exhaustive and genome-wide detection of HGT was developed, featuring the systematic analysis of BLAST hit distribution patterns in the context of a priori defined hierarchical evolutionary categories. Genes that fall beyond a series of statistically determined thresholds are identified as not adhering to the typical vertical history of the organisms in question, but instead having a putative horizontal origin. Tests on simulated genomic data suggest that this approach effectively targets atypically distributed genes that are highly likely to be HGT-derived, and exhibits robust performance compared to conventional BLAST-based approaches. This method was further tested on real genomic datasets, including Rickettsia genomes, and was compared to previous studies. Results show consistency with currently employed categories of HGT prediction methods. In-depth analysis of both simulated and real genomic data suggests that the method is notably insensitive to stochastic events such as gene loss, rate variation and database error, which are common challenges to the current methodology. An automated pipeline was created to implement this approach and was made publicly available at: https://github.com/DittmarLab/HGTector . The program is versatile, easily deployed, has a low requirement for computational resources. HGTector is an effective tool for initial or standalone large-scale discovery of candidate HGT-derived genes.
Thermal and Thermoelectric Transport in Nanostructures and Low-Dimensional Systems

Significant progress has been made in recent studies of thermal and thermoelectric transport phenomena in nanostructures and low-dimensional systems. This article reviews several intriguing quantum and classical size effects on thermal and thermoelectric properties that have been predicted by theoretical calculations or observed in experiments. Attention is focused on the Casimir limit in phonon boundary scattering and the effect of phonon confinement on the lattice thermal conductivity of semiconductor nanowires (NWs) and nanomeshes; the effects of thickness, lateral size, and interface interaction on the lattice thermal conductivity of carbon nanotubes (CNTs) and graphene; and the phonon-drag thermopower and quantum size effects on the thermoelectric power factor in semiconductor NWs. Further experimental and theoretical investigations are suggested for better understanding of some of these nanoscale transport phenomena.
Linear Convergence of Epsilon-Subgradient Descent Methods for a Class of Convex Functions

This paper establishes a linear convergence rate for a class of epsilon-subgradient descent methods for minimizing certain convex functions. Currently prominent methods belonging to this class include the resolvent (proximal point) method and the bundle method in proximal form (considered as a sequence of serious steps). Other methods, such as the recently proposed descent proximal level method, may also fit this framework depending on implementation. The convex functions covered by the analysis are those whose conjugates have subdifferentials that are locally upper Lipschitzian at the origin, a class introduced by Zhang and Treiman. We argue that this class is a natural candidate for study in connection with minimization algorithms.
Multipath Wireless Network Coding: A Population Game Perspective

We consider wireless networks in which multiple paths are available between each source and destination. We allow each source to split traffic among all of its available paths, and ask the question: how do we attain the lowest possible number of transmissions per unit time to support a given traffic matrix? Traffic bound in opposite directions over two wireless hops can utilize the ``reverse carpooling'' advantage of network coding in order to decrease the number of transmissions used. We call such coded hops as ``hyper-links''. With the reverse carpooling technique longer paths might be cheaper than shorter ones. However, there is a prisoners dilemma type situation among sources -- the network coding advantage is realized only if there is traffic in both directions of a shared path. We develop a two-level distributed control scheme that decouples user choices from each other by declaring a hyper- link capacity, allowing sources to split their traffic selfishly in a distributed fashion, and then changing the hyper-link capacity based on user actions. We show that such a controller is stable, and verify our analytical insights by simulation.
Pressure gradient effect on a particle velocity distribution

[1] In space plasma missions, measurements of the three-dimensional particle velocity distribution are used to examine the dynamical evolution of plasmas. The first velocity moment of the measured particle velocity distribution is often regarded as the bulk flow of the population. Accurate determination of bulk flows is crucial if the frozen-in-condition is judged by E + V × B = 0, where E is the electric field, V is the bulk flow, and B is the magnetic field. In this paper, we show that this first velocity moment computed from the measured particle velocity distribution can deviate substantially from the bulk motion of the particle population when a significant pressure gradient exists near the measurement location. The discrepancy, which arises from the diamagnetic drift with a finite Larmor radius effect, increases with increasing energy range used in the computation. The result calls for caution in the proper interpretation of this velocity moment and suggests a means to avoid error in the determination of bulk flow due to pressure gradient effects.
Volatile Compounds in Shergottite and Nakhlite Meteorites

— Vacuum pyrolysis and quadrupole mass spectrometry were used to measure evolved-gas profiles and total concentrations of H2O, CO2, CO, SO2, S2, H2S, HCl, Cl, and hydrocarbons in both exterior and interior samples of shergottites (ALHA77005, EETA79001, and Shergotty), a nakhlite (Nakhla), and eucrites (ALHA81001, EETA79004, and Pasamonte). Eucrites were analyzed as control samples to monitor effects of terrestrial weathering and contamination, relative to properties sought for the shergottite-nakhlite parent body. In contrast with eucrites, shergottites and Nakhla contain large proportions of their sulfur as oxidized sulfur compounds. Sulfate occurs in all shergottite and Nakhla samples and carbonate was confirmed in EETA79001 and Nakhla. Carbonate and sulfate abundances are inversely correlated but total chlorine abundance varies directly with fractional sulfate abundance. Most of the volatile compounds seem to be anhydrous, based on low bulk water contents in the meteorites (<0.1% H2O), although Nakhla might contain significant water that is chemically associated with chlorine. Traces of saturated and unsaturated hydrocarbons in some samples are most likely terrestrial contaminants. The indigenous volatile compounds indicate that the shergottite-nakhlite parent body was highly oxidizing and supported aqueous geochemistry during at least part of its history.
Detecting meaning in RSVP at 13 ms per picture

The visual system is exquisitely adapted to the task of extracting conceptual information from visual input with every new eye fixation, three or four times a second. Here we assess the minimum viewing time needed for visual comprehension, using rapid serial visual presentation (RSVP) of a series of six or 12 pictures presented at between 13 and 80 ms per picture, with no interstimulus interval. Participants were to detect a picture specified by a name (e.g., smiling couple) that was given just before or immediately after the sequence. Detection improved with increasing duration and was better when the name was presented before the sequence, but performance was significantly above chance at all durations, whether the target was named before or only after the sequence. The results are consistent with feedforward models, in which an initial wave of neural activity through the ventral stream is sufficient to allow identification of a complex visual stimulus in a single forward pass. Although we discuss other explanations, the results suggest that neither reentrant processing from higher to lower levels nor advance information about the stimulus is necessary for the conscious detection of rapidly presented, complex visual information.
Influence of anthropogenic sulfate and black carbon on upper tropospheric clouds in the NCAR CAM3 model coupled to the IMPACT global aerosol model

[1] The influence of anthropogenic aerosol (sulfate and soot) on upper tropospheric (UT) clouds through ice nucleation is studied using the NCAR Community Atmospheric Model Version 3 (CAM3) with a double moment ice microphysics treatment coupled to a global aerosol model (LLNL/UMich IMPACT). Present-day and preindustrial simulations are performed and compared for two scenarios. In the first scenario, the homogeneous freezing of sulfate particles dominates cirrus cloud formation in the upper troposphere (HOM). In the second scenario, both homogeneous and heterogeneous ice nucleation and their competition (HET) are allowed. In the HOM scenario, anthropogenic sulfate results in a global annual mean change of long-wave cloud forcing (LWCF) of 0.20 ± 0.09 W m−2 and short-wave cloud forcing (SWCF) of 0.30 ± 0.17 W m−2 and an increase of upper tropospheric/lower stratospheric (UT/LS) water vapor by ∼10%. In the HET scenario, anthropogenic soot may increase global cirrus cloud cover by ∼2% and UT/LS water vapor by 40% with a change in LWCF of 1.5 W m−2 (with 1.35 ± 0.15 W m−2 from surface soot and 0.12 ± 0.17 W m−2 from aircraft soot) if soot acts as efficient ice nuclei (IN) with a threshold ice nucleation RHi of 120–130%. Aerosol effects are most evident (larger than natural variability) over polar regions. However, their influence is significantly reduced if soot has a threshold RHi of 140% with an LWCF change of only 0.23 W m−2 (with 0.17 ± 0.18 W m−2 from surface soot and 0.06 ± 0.16 W m−2 from aircraft soot), and cloud forcing changes are statistically insignificant (less than the natural variability). Our results reinforce the importance of understanding ice nucleation on soot from the perspective of their global climate impact.
Bifurcations and patterns in compromise processes

Abstract We study an opinion dynamics model in which agents reach compromise via pairwise interactions. When the opinions of two agents are sufficiently close, they both acquire the average of their initial opinions; otherwise, they do not interact. Generically, the system reaches a steady state with a finite number of isolated, non-interacting opinion clusters (“parties”). As the initial opinion range increases, the number of such parties undergoes a periodic sequence of bifurcations. Both major and minor parties emerge, and these are organized in alternating pattern. This behavior is illuminated by considering discrete opinion states.
Robust speaker identification in noisy and reverberant conditions

Robustness of speaker recognition systems is crucial for real-world applications, which typically contain both additive noise and room reverberation. However, the combined effects of additive noise and convolutive reverberation have been rarely studied in speaker identification (SID). This paper addresses this issue in two phases. We first remove background noise through binary masking using a deep neural network classifier. Then we perform robust SID with speaker models trained in selected reverberant conditions, using bounded marginalization and direct masking. Evaluation results show that the proposed system substantially improves SID performance over related systems in a wide range of reverberation time and signal-to-noise ratios.
Development of and student reactions to an international accounting GIS case problem

A geographic information system (GIS) is an information technology tool which supports presentation, analysis and communication of the geospatial dimension of data. GIS tools have made significant contributions to decision making in marketing, finance, accounting and business intelligence. Business educators can help their students by using teaching resources that facilitate understanding and application of these powerful tools in online configurations similar to situations that graduates may encounter in their careers. This paper describes an international accounting GIS case, which was one module in a series of business GIS instructional modules. In addition, the paper provides feedback from students regarding the perceived benefits of using the case. Findings indicate that the international accounting GIS case is well received by students and contributes to student learning. Instructor notes are provided that include answers to the case questions.
Evidence-Based Phonological Assessment of Bilingual Children

Summary Evidence-based assessment ofphonological disorders in bilingualchildren should take into consider-ation recent theories of bilingualphonological representation. By as-sessing both languages and deter-mining how those languages inter-act, we can make a valid diagnosisand determine the child’s strengthsand weaknesses. Then we can uti-lize that information for planningintervention for bilingual childrenwith phonological disorders. References Fabiano, L. (2006). Phonological repre-sentation in bilingual Spanish-En-glish speaking children . Unpub-lished doctoral dissertation,Temple University, Philadelphia.Fabiano, L., & Goldstein, B. (2004a, Feb-ruary). Phonological cross-linguis-tic influence in sequential bilingualSpanish-English speaking children. Poster presented at the Interna-tional Clinical Phonetics and Lin-guistics Association Conference,Lafayette, LA.Fabiano, L., & Goldstein, B. (2004b,May). Phonological representationin simultaneous and sequential bi-lingual Spanish-English speakingchildren.
The Initial Mass Function of Low-Mass Stars and Brown Dwarfs in Taurus

By combining deep optical imaging and infrared spectroscopy with data from the Two-Micron All-Sky Survey (2MASS) and from previous studies (e.g., Briceno et al.), I have measured the initial mass function (IMF) for a reddening-limited sample in four fields in the Taurus star-forming region. This IMF is representative of the young populations within these fields for masses above 0.02 M☉. Relative to the similarly derived IMF for the Trapezium Cluster (Luhman et al.), the IMF for Taurus exhibits a modest deficit of stars above 1 solar mass (i.e., steeper slope), the same turnover mass (~0.8 M☉), and a significant deficit of brown dwarfs. If the IMF in Taurus were the same as that in the Trapezium, 12.8 ± 1.8 brown dwarfs (>0.02 M☉) are expected in these Taurus fields where only one brown dwarf candidate is found. These results are used to test theories of the IMF.
Human GM3 Synthase Attenuates Taxol-Triggered Apoptosis Associated with Downregulation of Caspase-3 in Ovarian Cancer Cells.

Background: Taxol (paclitaxel) inhibits proliferation and induces apoptosis in a variety of cancer cells, but it also upregulates cytoprotective proteins and/or pathways that compromise its therapeutic efficacy. Materials and Method: The roles of GM3 synthase (α2,3-sialyltransferase, ST3Gal V), in attenuating Taxol-induced apoptosis and triggering drug resistance were determined by cloning and overexpressing this enzyme in SKOV3 human ovarian cancer cell line, treating SKOV3 and the transfectants (SKOV3/GS) with Taxol and determining apoptosis, cell survival, clonogenic ability, and caspase-3 activation. Results: In this report, we demonstrated that Taxol treatment resulted in apoptosis which was associated with caspase-3 activation. Taxol treatment upregulated the expression of human GM3 synthase, an enzyme that transfers a sialic acid to lactosylceramide. Moreover, we cloned the full-length GM3 synthase gene and showed for the first time that forced expression of GM3 synthase attenuated Taxol-induced apoptosis and increased resistance to Taxol in SKOV3 cells. Conclusions: GM3 synthase overexpression inhibited Taxol-triggered caspase-3 activation, revealing that upregulation of GM3 synthase prevents apoptosis and hence reduces the efficacy of Taxol therapy.
Eternal inflation and the present universe

Abstract Eternally inflating universes can contain thermalized regions with different values of the cosmological parameters. In particular, the spectra of density fluctuations should be different, because of the different realizations of quantum fluctuations of the inflaton field. I discuss a general method for calculating probability distributions for such variable parameters and analyze the density fluctuation spectrum as a specific application.
The SNAP strong lens survey

Basic considerations of lens detection and identification indicate that a wide field survey of the types planned for weak lensing and Type Ia SNe with SNAP are close to optimal for the optical detection of strong lenses. Such a ''piggy-back'' survey might be expected even pessimistically to provide a catalogue of a few thousand new strong lenses, with the numbers dominated by systems of faint blue galaxies lensed by foreground ellipticals. After sketching out our strategy for detecting and measuring these galaxy lenses using the SNAP images, we discuss some of the scientific applications of such a large sample of gravitational lenses: in particular we comment on the partition of information between lens structure, the source population properties and cosmology. Understanding this partitioning is key to assessing strong lens cosmography's value as a cosmological probe.
When can statistical theories be causally closed

The notion of common cause closedness of a classical, Kolmogorovian probability space with respect to a causal independence relation between the random events is defined, and propositions are presented that characterize common cause closedness for specific probability spaces. It is proved in particular that no probability space with a finite number of random events can contain common causes of all the correlations it predicts; however, it is demonstrated that probability spaces even with a finite number of random events can be common cause closed with respect to a causal independence relation that is stronger than logical independence. Furthermore it is shown that infinite, atomless probability spaces are always common cause closed in the strongest possible sense. Open problems concerning common cause closedness are formulated and the results are interpreted from the perspective of Reichenbach's Common Cause Principle (RCCP).
Weighted Approximation of Functions on the Unit Sphere

The direct and inverse theorems are established for the best approximation in the weighted Lp space on the unit sphere of Rd+1, in which the weight functions are invariant under finite reflection groups. The theorems are stated using a modulus of smoothness of higher order, which is proved to be equivalent to a K-functional defined using the power of the spherical h-Laplacian. Furthermore, similar results are also established for weighted approximation on the unit ball and on the simplex of Rd.
Non-heme mononitrosyldiiron complexes: importance of iron oxidation state in controlling the nature of the nitrosylated products.

Mononitrosyldiiron complexes having either an [Fe(II)·{FeNO}(7)] or an [Fe(III)·{FeNO}(7)] core formulation have been synthesized by methods that rely on redox-state-induced differentiation of the diiron starting materials in an otherwise symmetrical dinucleating ligand environment. The synthesis, X-ray structures, Mossbauer spectroscopy, cyclic voltammetry, and dioxygen reactivity of [Fe(III)·{FeNO}(7)] are described.
Temporal Variability of Active Region Outflows

Recent observations from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode have shown that low-density areas on the periphery of active regions are characterized by strong blueshifts in the emission of spectral lines formed at 1?MK. These Doppler shifts have been associated with outward propagating disturbances observed with extreme-ultraviolet and soft X-ray imagers. Since these instruments can have broad temperature responses, we investigate these intensity fluctuations using the monochromatic imaging capabilities of the EIS wide slit (slot) and confirm their 1?MK nature. We also look into their spectral temporal variability using narrow slit observations and present the first Doppler movies of the outflow regions. We find that the Fe XII 195.119?? blueshifted spectral profiles at their footpoints exhibit transient blue wing enhancements on timescales as short as the 5 minute cadence. We have also looked at the fan peripheral loops observed at 0.6?MK in Si VII 275.368?? in those regions and find no sign of the recurrent outward propagating disturbances with velocities of 40-130?km s?1 seen in Fe XII. We do observe downward trends (15-20?km s?1) consistent with the characteristic redshifts measured at their footpoints. We, therefore, find no evidence that the structures at these two temperatures and the intensity fluctuations they exhibit are related to one another.
Some examples in the realization of symmetry

Abstract I briefly discuss three phenomena arising in recent work where the realization of symmetries in quantum mechanics is unusual. The first of these is, I believe, the very simplest realization of non-trivial confinement by a mechanism of charge-flux frustration. It arises in models having several coupled abelian Chern-Simons gauge symmetries, which closely resemble effective theories used for the quantum Hall effect. The second is symmetry obstruction by non-abelian flux, which has implications for 2+1 dimensional supergravity. Third is the possibility of new varieties of quantum statistics: non-abelian and projective.
Dependent children and aged parents: funding education and social security in an aging economy

In the last few decades in the United States birth rates have declined and longevity has risen while productivity growth has slowed. Given such changes, the increasing burden of funding programs for the elderly is likely to shift resources away from the young and toward the elderly. This paper uses an overlapping generations framework to examine the effects of tax policies on an aging economy. We find that if the quality of the education system is sufficiently high then raising the education tax rate and subsequently lowering the social security tax rate enhances growth and welfare.
Fourier Analysis of Numerical Algorithms for the Maxwell Equations

The Fourier method is used to analyze the dispersive, dissipative, and isotropy errors of various spatial and time discretizations applied to the Maxwell equations on multi-dimensional grids. Both Cartesian grids and non-Cartesian grids based on hexagons and tetradecahedra are studied and compared. The numerical errors are quantitatively determined in terms of phase speed, wavenumber, propagation direction, gridspacings, and CFL number. The study shows that centered schemes are more efficient and accurate than upwind schemes and the non-Cartesian grids yield superior isotropy than the Cartesian ones. For the centered schemes, the staggered grids produce less errors than the unstaggered ones. A new unstaggered algorithm which has all the best properties is introduced. Using an optimization technique to determine the nodal weights, the new algorithm provides the highest accuracy among all the schemes discussed. The study also demonstrates that a proper choice of time discretization can reduce the overall numerical errors due to the spatial discretization.
Adrenal radiography: problems and pitfalls in adrenal localization.

The traditional preoperative localization of adrenal tumors has employed one or more of the following radiographic techniques: plain abdominal films, intravenous urography, adrenal venography and venous sampling, arteriography, ultrasonography, computed tomographic scanning, and scintiscanning. These localization techniques may be divided into invasive or noninvasive types with each technique having different degrees of sensitivity and specificity for the establishment of adrenal disease. The diagnostic accuracy of these radiographic techniques is reviewed for a 5-year series in a university hospital with special emphasis on false-positive localization. The techniques employed in localization and their sequence vary and depend on whether adrenal medullary or adrenal cortical disease was suspected, and whether or not the patient was protected by pharmacologic preparation.
A directed metalation route to the zwitterionic indole alkaloids. Syntheses of indolo[2,3-a]quinolizine, flavopereirine, flavocarpine, and dihydroflavopereirine

Abstract A protocol involving beta-lithiation of 2-(2-pyridinyl)indoles (4 → 5) and subsequent reaction with bromoacetaldehyde or oxirane has led to syntheses of the alkaloids indolo[2,3-a]quinofizine (1), flavopereirine (2), flavocarpine (21), and dihydroflavopereirine (24).
Potential incorporation of transuranics into uranium phases

The UO{sub 2} in spent nuclear fuel is unstable under moist oxidizing conditions and will be altered to uranyl oxide hydrate phases. The transuranics released during the corrosion of spent fuel may also be incorporated into the structures of secondary U{sup 6+} phases. The incorporation of radionuclides into alteration products will affect their mobility. A series of precipitation tests were conducted at either 150 or 90 C for seven days to determine the potential incorporation of Ce{sup 4+} and Nd{sup 3+} (surrogates for Pu{sup 4+} and Am{sup 3+}, respectively) into uranium phases. Ianthinite ([U{sub 2}{sup 4+}(UO{sub 2}){sub 4}O{sub 6}(OH){sub 4}(H{sub 2}O){sub 4}](H{sub 2}O){sub 5}) was produced by dissolving uranium oxyacetate in a solution containing copper acetate monohydrate as a reductant. The leachant used in these tests were doped with either 2.1 ppm cerium or 399 ppm neodymium. Inductively coupled plasma-mass spectrometer (ICP-MS) analysis of the solid phase reaction products which were dissolved in a HNO{sub 3} solution indicates that about 306 ppm Ce (K{sub d} = 146) was incorporated into ianthinite, while neodymium contents were much higher, being approximately 24,800 ppm (K{sub d} = 62). Solid phase examinations using an analytical transmission electron microscope/electron energy-loss spectrometer (AEM/EELS) indicate a uniform distribution of Nd, while Ce contents were below detection. Becquerelite (Ca[(UO{sub 2}){sub 6}O{sub 4}(OH){sub 6}]{center_dot}8H{sub 2}O) was produced by dissolving uranium oxyacetate in a solution containing calcium acetate. The leachant in these tests was doped with either 2.1 ppm cerium or 277 ppm neodymium. ICP-MS results indicate that about 33 ppm Ce (K{sub d}=16) was incorporated into becquerelite, while neodymium contents were higher, being approximately 1,300 ppm (K{sub d}=5). Homogeneous distribution of Nd in the solid phase was noted during AEM/EELS examination, and Ce contents were also below detection.
AN "ANTI-HASSE PRINCIPLE" FOR PRIME TWISTS

Given an algebraic curve C/ℚ having points everywhere locally and endowed with a suitable involution, we show that there exists a positive density family of prime quadratic twists of C violating the Hasse principle. The result applies in particular to wN-Atkin–Lehner twists of most modular curves X0(N) and to wp-Atkin–Lehner twists of certain Shimura curves XD+.
On Cyclicality in the Current and Financial Accounts: Evidence from Nine Industrial Countries

The paper investigates cyclical fluctuations in the current and financial accounts of the balance of payments and major underlying components for nine industrial countries. Explanatory variables are domestic output growth, price inflation, real exchange rate fluctuations, energy price inflation, global growth, and regional growth. The evidence indicates the importance of fluctuations in output growth to the cyclicality of the current and financial balances. High domestic growth tends to stimulate financial inflows and provides adequate resources to finance a large current account deficit. Other factors appear to be less important to the cyclicality of the current and financial balances and their negative correlations.
Geographical and seasonal distribution of tropical tropopause thin clouds and their relation to deep convection and water vapor viewed from satellite measurements

[1] The climatologies of deep convection, thin clouds, and water vapor measurements from four independent satellites are compared in this study. Deep convection reaching the tropical tropopause layer (TTL) is indicated by the area of the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) 20 dBZ reflectivity reaching 14 km and the area of the TRMM visible and infrared scanner (VIRS) brightness temperature at 10.8 μm (TB11) < 210 K. TTL clouds are identified by 17 years of Stratospheric Aerosol and Gas Experiment (SAGE) II measurements and by 1 year of Earth Observing System (EOS) Microwave Limb Sounder (MLS) ice water content in 2005. TTL water vapor is estimated from 2005 EOS MLS retrievals. Results suggest that TTL clouds are geographically and seasonally correlated with deep convection as inferred from the area of TB11 < 210 K. Patterns of regional differences of seasonal variations of deep convection are also related to the regional differences of seasonal variations of TTL clouds. By grouping the Ice Cloud and Land Elevation Satellite/Geoscience Laser Altimeter System (ICESat/GLAS) layer cloud products, we find that there is a general spatial correlation between the largest, thickest TTL layer clouds with the highest optical depth and the regions with the most intense deep convection. MLS CO and water vapor at 146 hPa have similar geographical and seasonal variations as deep convection and TTL clouds. EOS MLS 100 hPa water vapor is low over the west Pacific Ocean at the same location and time as more TTL clouds are observed.
Reaction of Allylmanganese(II) Reagents with Aldehydes

Abstract : The reaction of allylmanganese(II) reagents with aldehydes gives alcohols with high regioselectivity. The allylmanganese(II) reagents are prepared by transmetallation between manganese(II) chloride and allyllithium compounds which are generated from allyl phenyl sulfides by reductive lithiation.
Electro-chemo-mechanical interpretation of Pt and Au-electroded relaxationless ionic polymer-metal composites

Until now there have been few studies on the electrochemical behaviors of the electrode surface of Ionic Polymer- Metal Composites (IPMCs). In general, the electrochemical reactions under imposed electric fields cause the variations of overall resistance and capacitance of IPMCs and, therefore, lead to changes in the actuation behavior of IPMCs. The electro-chemo-mechanical interpretation of the electrodes made with Pt and Au are described in this paper. The standard electrochemical analyses, including voltammetry and electrochemical impedance spectroscopy on the electrode surface, were carried out in aqueous (water) and non-aqueous (ionic liquid) environments. The redox behaviors over a wide range of operation were analyzed using the cyclic voltammetry method. A load cell was used in measuring blocking forces. The experimental results suggest that the selection of appropriate electrode materials and solvents, and operating conditions are key parameters to predict the performance of IPMC actuators. It should be pointed out that unwanted reactions caused by the electrocatalyst under certain conditions can be avoided or minimized when an effective electrode-material is selected. IPMC samples having highly conductive electrodes or being solvated with ionic liquids generate improved and repeatable actuation with nearly no relaxation. Also, a thicker IPMC sample than conventional 50-300 micron thick IPMCs did not show any relaxation behaviors.
Mendelssohn's Other Concerto: The Changing Reception of the Piano Concerto No. 2, Op. 40, in D minor

Felix Mendelssohn's two mature piano concertos, Op. 25 in G minor (1831–32) and Op. 40 in D minor (1837), were widely performed in the nineteenth century. In the twentieth century, the D-minor Concerto fell completely out of favor and came to be regarded as a work the composer had completed hurriedly. However, the numerous extant autograph sources for the second Concerto reveal that Mendelssohn considered it worthy of the meticulous revision customary of his major artistic efforts. The problematic reception of the D-minor Concerto was due to a convergence of factors, not the least of which was the highly favorable reception of its predecessor, Op. 25, deemed historically significant due to its formal innovations. But more subtle forces also shaped the decline of Op. 40, including a perceived seriousness of musical content as opposed to popularizing virtuosic display, as well as a long history of performance by women and amateurs rather than male virtuosi. In addition, the second Piano Concerto's biographi...
Alternative approaches to cost containment in a cap-and-trade system.

We compare several emissions reduction instruments, including quantity policies with banking and borrowing, price policies, and hybrid policies (safety valve and price collar), using a dynamic model with stochastic baseline emissions. The instruments are compared under the design goal of obtaining the same expected cumulative emissions across all options. Based on simulation analysis with the model parameterized to values relevant to proposed US climate mitigation policies, we find that restrictions on banking and borrowing, including the provision of interest rates on the borrowings, can severely limit the value of the policy, depending on the regulator-chosen allowance issuance path. Although emissions taxes generally provide the lowest expected abatement costs, a cap-and-trade system combined with either a safety valve or a price collar can be designed to provide expected abatement costs near those of a tax, but with lower emissions variance than a tax. Consistently, a price collar is more cost-effective than a safety valve for a given expected cumulative emissions outcome because it encourages inexpensive abatement when abatement costs decline.
Halogenation reactions of epoxides

Abstract The halogenation of aryl and alkyl epoxides using elemental bromine or iodine has been studied.
A Framework for Closed-Form Displacement Analysis of Planar Mechanisms

This paper presents a closed-form approach, based on the theory of resultants, to the displacement analysis problem of planar n-link mechanisms. The successive elimination procedure presented herein generalizes the Sylvester’s dialytic eliminant for the case when p equations (p ≥ 3) are to be solved in p unknowns. Conditions under which the method of successive elimination can be used to reduce p equations (in p unknowns) into a univariate polynomial, devoid of extraneous roots, are presented. This univariate polynomial corresponds to the I/O polynomial of the mechanism. A comprehensive treatment is also presented on some of the problems associated with the conversion of transcendental loop-closure equations, into an algebraic form, using tangent half-angle substitutions. It is shown how trigonometric manipulations in conjunction with tangent half-angle substitutions can lead to non-trivial extraneous roots in the solution process. Theoretical conditions for identifying and eliminating these extraneous roots are presented. The computational procedure is illustrated through the displacement analysis of a 10-link 1-DOF mechanism with 4 independent loops.
Hybrid methods for determining time-optimal, constrained spacecraft reorientation maneuvers

Abstract Time-optimal spacecraft slewing maneuvers with path constraints are difficult to compute even with direct methods. This paper examines the use of a hybrid, two-stage approach, in which a heuristic method provides a rough estimate of the solution, which then serves as the input to a pseudospectral optimizer. Three heuristic methods are examined for the first stage: particle swarm optimization (PSO), differential evolution (DE), and bacteria foraging optimization (BFO). In this two-stage method, the PSO-pseudospectral combination is approximately three times faster than the pseudospectral method alone, and the BFO-pseudospectral combination is approximately four times faster; however, the DE does not produce an initial estimate that reduces total computation time.
Environmental policy in majoritarian systems

Abstract This paper sheds new light on the determination of environmental tax policies in majoritarian federal electoral systems, such as the U.S., and derives implications for the environmental federalism debate on whether the national or local government should have authority over environmental taxes. In the absence of majority bias, the socially preferred policy would be federal district-level taxation which accounts both for cross-boundary pollution and differences in industry concentration across districts. In majoritarian systems, however, where the legislature consists of geographically distinct electoral districts, the majority party (at the national or state level) favors home districts; depending on the location of polluting industries and the associated damages, the majority party may therefore impose sub-optimally high or low pollution taxes due to a majority bias . Majority bias can influence the social-welfare ranking of alternative environmental tax policies. In some cases, majority bias may make decentralized or federal uniform taxation the preferred solution.
Local area navigation using sonar feature extraction and model-based predictive control

This paper demonstrates a method to navigate an autonomous underwater vehicle in a local area using an acoustic sensor for position information derived from feature detection. A dynamic model of the vehicle response is used for control between location updates. Favorable results have been found using this approach, and precision positioning of the vehicle to centimeters has been accomplished. Another part of the problem is the need to provide a high-frequency update of vehicle position in order to close the positioning servo loops. Using sonar image feature extraction is necessarily time consuming and therefore is performed in a tactical level process providing asynchronous data to the tactical navigator. It follows that some form of fast dead reckoning must be performed in the execution level either by INS-Doppler or by water speed and heading data or by a model-based predictor. This paper deals with the use of a model-based predictor technique where knowledge of the dynamic model of the vehicle provides...