cssi/SciSciGPT-SciSciNet huggingface dataset:
A note on space noncommutativity

Abstract We consider a two-point spatial lattice approximation to an open string moving in a flat background with B field. It gives a constrained dipole system under the influence of a vector potential. Solving and quantizing this system recover all the essential features of a noncommutative space. In particular, open string interactions induce a canonical product structure on the Hilbert space of the dipole system. It coincides with the usual star product, even though the position operators can be thought of as mutually commuting. Modification of gauge transformations in this noncommutative space also naturally emerges.
Contact Between Plates and Unilateral Supports

Etude de la tendance d'une plaque rectangulaire chargee lateralement a se desolidariser de ses supports. Dans le cas d'une plaque carree une transformation integrale finie convertit les equations en series duales resultant de l'approche de Levy-Nadai en une equation integrale singuliere qui peut etre resolue par des methodes standards. L'extension du contact ne depend que des proprietes geometriques et elastiques de la plaque
Affine Stanley symmetric functions for classical types

We introduce affine Stanley symmetric functions for the special orthogonal groups, a class of symmetric functions that model the cohomology of the affine Grassmannian, continuing the work of Lam and Lam, Schilling, and Shimozono on the special linear and symplectic groups, respectively. For the odd orthogonal groups, a Hopf-algebra isomorphism is given, identifying (co)homology Schubert classes with symmetric functions. For the even orthogonal groups, we conjecture an approximate model of (co)homology via symmetric functions. In the process, we develop type B and type D non-commutative k-Schur functions as elements of the affine nilCoxeter algebra that model homology of the affine Grassmannian. Additionally, Pieri rules for multiplication by special Schubert classes in homology are given in both cases. Finally, we present a type-free interpretation of Pieri factors, used in the definition of noncommutative k-Schur functions or affine Stanley symmetric functions for any classical type.
The submartingale problem for a class of degenerate elliptic operators

We consider the degenerate elliptic operator acting on \({C^2_b}\) functions on [0,∞)d: $$\mathcal{L}f(x)=\sum_{i=1}^d a_i(x) x_i^{\alpha_i} \frac{\partial^2 f}{\partial x_i^2} (x) +\sum_{i=1}^d b_i(x) \frac{\partial f}{\partial x_i}(x), $$ where the ai are continuous functions that are bounded above and below by positive constants, the bi are bounded and measurable, and the \({\alpha_i\in (0,1)}\) . We impose Neumann boundary conditions on the boundary of [0,∞)d. There will not be uniqueness for the submartingale problem corresponding to \({\mathcal{L}}\) . If we consider, however, only those solutions to the submartingale problem for which the process spends 0 time on the boundary, then existence and uniqueness for the submartingale problem for \({\mathcal{L}}\) holds within this class. Our result is equivalent to establishing weak uniqueness for the system of stochastic differential equations $$ {\rm d}X_t^i=\sqrt{2a_i(X_t)} (X_t^i)^{\alpha_i/2}{\rm d}W^i_t + b_i(X_t) {\rm d}t + {\rm d}L_t^{X^i},\quad X^i_t \geq 0, $$ where \({W_t^i}\) are independent Brownian motions and \({L^{X_i}_t}\) is a local time at 0 for Xi.
Experimental Determination of the Propagation Pressure of Circular Pipes

Local geometric imperfections on pipes under external pressure can lead to local buckling which under the ''right'' conditions can cause the initiation of a propagating buckle. This buckle, driven by the pressure, propagates up and down the pipe flattening it. The lowest pressure which can sustain a propagating buckle is called the propagation pressure and is a characteristic pressure of the pipe. Experiments have shown this pressure to depend on the post yield characteristics of the pipe material behavior as well as the diameter-to-thickness ratio of the pipe. The collapse mechanism has been modeled by the collapse of a ring under external pressure. By identifying the lowest postbuckling pressure of the ring with the propagation pressure, an empirical expression for the latter quantity has been established. 11 refs.
Education and allocative efficiency: household income growth during rural reforms in China

This paper studies the contribution of schooling to rural income in China during factor market liberalization between 1986 and 1995. The relaxation of controls permitted farm households to reallocate productive inputs from agriculture to nonagricultural activities. It is hypothesized that education facilitates this adjustment. Panel data from Sichuan province suggest that schooling enhanced the ability of farmers to devote labor and capital to nonfarm production given the evidence that less-than-optimum levels of these inputs were allocated to nonagricultural uses. During the transition, the expansion of nonfarm activities contributed significantly to household income growth.
An experimental investigation of the turbulent structure in a two- dimensional momentumless wake

Mean velocity profiles have been measured in the wake of a two-dimensional airfoil with and without mass injection through a slit along its rear end. In particular, four cases have been documented: (a) a pure wake (no injection), (b) a weak wake (some injection), (c) a momentumless wake (injection adjusted to provide a thrust which exactly cancels the model's drag), and (d) a weak jet (more injection than necessary to cancel the drag). These mean velocity profiles clearly show the difference in momentum deficit for the four cases. When non-dimensionalized, the velocity profiles are self-similar.Smoke-wire flow visualizations are also presented for both the near wake (0 < x/d < 30) and the far wake (45 < x/d < 75). The characteristic geometry of large-scale turbulent vortical structures is easily identifiable for the wake and jet cases, while the structures for the momentumless state are neither wake-like nor jet-like. Beyond about 45 diameters downstream, turbulent structures for the momentumless case become quite weak and can barely be observed.For the momentumless wake at Re = 5400, the axial, lateral, and transverse turbulence intensities as well as the Reynolds stress were measured. Similarity of the axial and the transverse turbulence intensities was observed; the overall shape of those profiles is Gaussian except for the very near-wake region. The mean centreline velocity difference decays much faster (x−0.92) than the axial turbulent intensity (x−0.81). Consequently, the mean shear practically disappears far downstream; the flow becomes nearly isotropic beyond about 45 body diameters from the model. This turbulence behaviour is quite different from that of plane wakes or jets but rather closer to the case of grid turbulence.
New analysis and results for the Frank---Wolfe method

We present new results for the Frank---Wolfe method (also known as the conditional gradient method). We derive computational guarantees for arbitrary step-size sequences, which are then applied to various step-size rules, including simple averaging and constant step-sizes. We also develop step-size rules and computational guarantees that depend naturally on the warm-start quality of the initial (and subsequent) iterates. Our results include computational guarantees for both duality/bound gaps and the so-called FW gaps. Lastly, we present complexity bounds in the presence of approximate computation of gradients and/or linear optimization subproblem solutions.
Hard X-Ray Bursts from flares behind the Solar Limb

The determination of the location of the region of origin of hard X-rays is important in evaluating the importance of 10–100 keV electrons in solar flares and in understanding flare particle acceleration. At present only limb-occulted events are available to give some information on the height of X-ray emission. In fifteen months of OSO-7 operation, nine major soft X-ray events had no reported correlated Hα flare. We examine the hard X-ray spectra of eight of these events with good candidate X-ray flare producing active regions making limb transit at the time of the soft X-ray bursts. All eight bursts had significant X-ray emission in the 30–44 keV range, but only one had flux at the 3σ level above 44 keV. The data are consistent with most X-ray emission occurring in the lower chromosphere, but some electron trapping at high altitudes is necessary to explain the small nonthermal fluxes observed.
Corporate Ethical Values, Group Creativity, Job Satisfaction and Turnover Intention: The Impact of Work Context on Work Response

A corporate culture strengthened by ethical values and other positive business practices likely yields more favorable employee work responses. Thus, the purpose of this study was to assess the degree to which perceived corporate ethical values work in concert with group creativity to influence both job satisfaction and turnover intention. Using a self-report questionnaire, information was collected from 781 healthcare and administrative employees working at a multi-campus education-based healthcare organization. Additional survey data was collected from a comparative convenience sample of 127 sales and marketing employees working for a variety of firms operating in the south-central United States. The results indicated that group creativity and corporate ethical values were positively related, and that both variables were associated with increased job satisfaction. Conversely, corporate ethical values and job satisfaction were associated with decreased turnover intention. Sales managers should create work cultures that precipitate increased ethical values and group creativity, and suggestions about how they may institutionalize these factors are provided.
Replacing energy by von Neumann entropy in quantum phase transitions

We propose that quantum phase transitions are generally accompanied by non-analyticities of the von Neumann (entanglement) entropy. In particular, the entropy is non-analytic at the Anderson transition, where it exhibits unusual fractal scaling. We also examine two dissipative quantum systems of considerable interest to the study of decoherence and find that non-analyticities occur if and only if the system undergoes a quantum phase transition.
Glass transition by gelation in a phase separating binary alloy.

We use molecular dynamics simulations to show that glass transition in a model phase separating amorphous alloy, ${\mathrm{Cu}}_{50}{\mathrm{Nb}}_{50}$, occurs by gelation. At the glass transition, a mechanically stiff, percolating network of atoms with icosahedral local packing forms at the interfaces between compositionally enriched regions. This low-energy network halts coarsening of the phase-separated structure and imparts shear resistance. These features of glass transition are remarkably similar to gelation processes in polymeric and colloidal gels.
Superfluid transition of 4He confined in porous glasses

Abstract Recent results of superfluid density and heat capacity measurements of 4 He confined in porous Vycor and aerogel glasses of very high porosity are reviewed. These measurements support the interpretation that the superfluid transition of 4 He confined in Vycor belongs to the same universality class as that of bulk 4 He. The superfluid density of 4 He in aerogel glass can be described by a simpel power law to a reduced temperature of 10 -4 K; however, the resultant critical exponent and heat capacity behavior are found to be distinctly different from that of bulk.
Revisiting the Hanging Tree

In 1994 V. A. C. Gatrell published The Hanging Tree: Execution and the English People 1770-1868. Though the book has been widely cited by historians, its complex argument about the relationship between punishment and culture has been too little understood. The work has also failed to win the wider audience it deserves among social scientists. The purpose of this review is to explicate Gatrell's thesis, making clear the psychoanalytic assumptions that guide his investigation. It also evaluates his investigation. It also evaluates his claims about the impact and meaning of a revolution in sensibility in connection with the decline in the use of capital punishment and the eventual disappearance of the execution from public view. Even as it acknowledges the striking importance of his historical research, this essay raises questions about the causal explanation Gatrell offers for the remarkable transformation he describes.
Synthesis of (Hetaryl)alkylamines from the Reactions of 2‐Aminopyrimidine, 2‐Aminothiazole, and 2‐Aminothiazoline with Benzyl Bromide and Xylylene Dibromides

Abstract Alkylation reactions of 2‐aminopyrimidine, 2‐aminothiazole, 2‐aminothiazoline, and their Cbz‐protected derivatives are described. Reactions with benzyl bromide proceed to give monoalkylated products with 2‐aminopyrimidine and 2‐aminothiazole, but 2‐aminothiazoline gives a dialkylated product. Reactions with xylylene dibromides are complicated by the tendency to form intramolecularly cyclized products with the ortho‐dibromide and insoluble products with the meta‐ and para‐dibromides.
Interlaminar Shear Strain Measurements in Cord-Rubber Composites

The present work is an experimental study using an X-ray technique to measure directly the internal distribution of interlaminar-shear deformations which occur during uniaxial extension of two-ply, cord-rubber, angle-ply laminates—both balanced and unbalanced. Significant interlaminar-shear strains were developed between the two generally orthotropic layers of one-inch-wide specimens, which decreased almost linearly from a maximum at the edges to zero at the center line. These measurements, and those as a function of cord angle, were in good agreement with predictions obtained from various theories of laminated shear-flexible composites.
Effects of vacancy-solute clusters on diffusivity in metastable Fe-C alloys

Diffusivity in defected crystals depends strongly on the interactions among vacancies and interstitials. Here we present atomistic analyses of point-defect cluster (PDC) concentrations and their kinetic barriers to diffusion in ferritic or body-centered-cubic (bcc) iron supersaturated with carbon. Among all possible point-defect species, only monovacancies, divacancies, and the PDC containing one vacancy and two carbon atoms are found to be statistically abundant. We find that the migration barriers of these vacancy-carbon PDCs are sufficiently high compared to that of monovacancies and divacancies. This leads to decreased self-diffusivity in bcc Fe with increasing carbon content for any given vacancy concentration, which becomes negligible when the local interstitial carbon concentration approaches twice that of free vacancies. These results contrast with trends observed in fcc Fe and provide a plausible explanation for the experimentally observed carbon dependence of volume diffusion-mediated creep in ferritic (bcc) Fe-C alloys. Moreover, this approach represents a general framework to predict self-diffusivity in alloys comprising a spectrum of point-defect clusters based on an energy-landscape survey of local energy minima (formation energies governing concentrations) and saddle points (activation barriers governing mobility).
Non-Fermi liquid fixed point in 2 + 1 dimensions

Abstract We construct models of excitations about a Fermi surface that display calculable deviations from Fermi liquid behavior in the low-energy limit. They arise as a consequence of coupling to a Chern-Simons gauge field, whose fluctuations are controlled through a 1 k x interaction. The Fermi liquid fixed point is shown to be unstable in the infrared for x ν = 1 2 quantum Hall state and to the normal state of copper-oxide superconductors.
Changes in Factor Betas and Risk Premiums Over Varying Market Conditions

We show risk exposures and premiums associated with the Chen, Roll, and Ross (1986) risk factors change over time and depend on stock market and business cycle condition. Findings also indicate that factor risk premiums change sign between January and non-January, especially during bull markets. These findings serve as a caveat for portfolio managers who allocate assets to match desired exposures to key macroeconomic risk factors.
The effect of nonuniform fluid flow distribution on the thermal performance of solar collector

Abstract In the design of solar collector, every effort is made to provide an uniform fluid flow distribution among the flow channels of the collector. Economical and space considerations, however, may make the uniform fluid flow distribution through the solar collector unrealistic. If the fluid flow distribution is not uniform, the thermal performance of the solar collector may deteriorate. A numerical method is developed for determination of the deterioration of thermal performance of solar collector due to this flow nonuniformity effect. Using several typical fluid flow maldistribution models, the collector efficiency and its deterioration are determined for various collector design and operating conditions.
SIMPLE REGULAR SKEW GROUP RINGS

Given a group G acting on a ring R via α:G → Aut(R), one can construct the skew group ring R*αG. Skew group rings have been studied in depth, but necessary and sufficient conditions for the simplicity of a general skew group ring are not known. In this paper, such conditions are given for certain types of skew group rings, with an emphasis on Von Neumann regular skew group rings. Next the results of the first section are used to construct a class of simple skew group rings. In particular, we obtain a more efficient proof of the simplicity of a certain ring constructed by J. Trlifaj.
Dimanganese complexes of a septadentate ligand. Functional analogues of the manganese pseudocatalase

Preparation de 2 nouveaux complexes de Mn(II): Mn 2 (L) Cl 3 et Mn 2 (L)(OH) Br 2 , dont on etudie la structure en solution par RPE. Etude par voltammetrie cyclique. Ce sont les premiers analogues fonctionnels de la pseudocatalase. (HL=N,N,N',N'-tetrakis(methylene-2 benzimidazolyl)-1,3 diamino-1,3 propanol-2)
Neurotransmitter uptake: A tool in identifying neurotransmitter-specific pathways

Publisher Summary This chapter describes the neurotransmitter uptake as a tool in identifying neurotransmitter-specific pathways. The location of norepinephrine (NE)-containing neurons in the brain has been well studied by histochemical methods. The uptake of NE by slices of rat brain or by synaptosomal preparations from brain is also well studied and has been found to be sodium-dependent, ouabain-sensitive and saturable. There is abundant evidence that the sites of NE uptake in brain, under high-affinity conditions are localized to NE-containing neurons. It is observed that catecholamine neurons have a reserpine resistant mechanism for accumulating NE. Moreover, the uptake of radioactive NE is markedly reduced in tissue which has had its NE neurons destroyed by pretreatment with the drug 6-hydroxydopamine, by placement of electrolytic lesions in the ascending NE tracts or by destruction of NE cell bodies in the locus coeruleus. It is also known that NE is accumulated by more than one system in the brain tissue. There appears to be both a high and low affinity uptake system, and it is the high affinity system which appears to be localized to NE containing neurons.
Regularity of Rational Vertex Operator Algebras

Rational vertex operator algebras, which play a fundamental role in rational conformal field theory (see [BPZ] and [MS]), single out an important class of vertex operator algebras. Most vertex operator algebras which have been studied so far are rational vertex operator algebras. Familiar examples include the moonshine module V ♮ ([B], [FLM], [D2]), the vertex operator algebras VL associated with positive definite even lattices L ([B], [FLM], [D1]), the vertex operator algebras L(l, 0) associated with integrable representations of affine Lie algebras [FZ] and the vertex operator algebras L(cp,q, 0) associated with irreducible highest weight representations for the discrete series of the Virasoro algebra ([DMZ] and [W]). A rational vertex operator algebra as studied in this paper is a vertex operator algebra such that any admissible module is a direct sum of simple ordinary modules (see Section 2). It is natural to ask if such complete reducibility holds for an arbitrary weak module (defined in Section 2). A rational vertex operator algebra with this property is called a regular vertex operator algebra. One motivation for studying such vertex operator algebras arises in trying to understand the appearance of negative fusion rules (which are computed by the Verlinde formula) for vertex operator algebras L(l, 0) for certain rational l (cf. [KS] and [MW]). In this paper we give several sufficient conditions under which a rational vertex operator algebra is regular. We prove that the rational vertex operator algebras V , L(l, 0) for positive integers l, L(cp,q, 0) and VL for positive definite even lattices L are regular. Our result for L(l, 0) implies that any restricted integrable module of level l for the corresponding affine Lie algebra is a direct sum of irreducible highest weight integrable modules. This result is expected to be useful in comparing the construction of tensor product of modules for L(l, 0) in [F] based on Kazhdan-Lusztig’s approach [KL] with the construction of tensor product of modules [HL] in this special case. We should remark that VL in general is a vertex algebra in the sense of [DL] if L is not positive definite. In this case we establish the complete reducibility of any weak module. Since the definition of vertex operator algebra is by now well-known, we do not define vertex operator algebra in this paper. We refer the reader to [FLM] and [FHL] for their elementary properties. The reader can find the details of the constructions of V ♮ and VL in [FLM], and L(l, 0) and L(cp,q, 0) in [DMZ], [DL], [FLM], [FZ], [L1] and [W].
Ultrasound-promoted synthesis of nitriles from aldoximes under ambient conditions

Copper(II) acetate proves to be an active catalyst for ultrasound-promoted conversion of aldoximes into nitriles. This dehydration reaction was carried out in acetonitrile under ambient conditions to provide nitriles with moderate tolerance toward water, which allows one-pot synthesis of a nitrile from an aldehyde with minimal purification.
Mode-resolved photon counting via cascaded quantum frequency conversion

Resources for the manipulation and measurement of high-dimensional photonic signals are crucial for implementing qudit-based applications. Here we propose potentially high-performance, chip-compatible devices for such purposes by exploiting quantum frequency conversion in nonlinear optical media. Specifically, by using sum-frequency generation in a χ(2) waveguide, we show how mode-resolved photon counting can be accomplished for telecom-band photonic signals subtending multiple temporal modes. Our method is generally applicable to any nonlinear medium with arbitrary dispersion properties.
TATE COHOMOLOGY AND PERIODIC LOCALIZATION OF POLYNOMIAL FUNCTORS

In this paper, we show that Goodwillie calculus, as applied to functors from stable homotopy to itself, interacts in striking ways with chromatic aspects of the stable category. Localized at a fixed prime p, let T(n) be the telescope of a vn self map of a finite S–module of type n. The Periodicity Theorem of Hopkins and Smith implies that the Bousfield localization functor associated to T(n)* is independent of choices. Goodwillie’s general theory says that to any homotopy functor F from S–modules to S–modules, there is an associated tower under F, {PdF}, such that F→PdF is the universal arrow to a d–excisive functor. Our first main theorem says that PdF→Pd-1F always admits a homotopy section after localization with respect to T(n)* (and so also after localization with respect to Morava K–theory K(n)*). Thus, after periodic localization, polynomial functors split as the product of their homogeneous factors. This theorem follows from our second main theorem which is equivalent to the following: for any finite group G, the Tate spectrum \({\mathcal{T}}_{G}(T(n))\) is weakly contractible. This strengthens and extends previous theorems of Greenlees–Sadofsky, Hovey–Sadofsky, and Mahowald–Shick. The Periodicity Theorem is used in an essential way in our proof. The connection between the two theorems is via a reformulation of a result of McCarthy on dual calculus.
A New Technique for Determining Europium Abundances in Solar-Metallicity Stars

We present a new technique for measuring the abundance of europium, a representative r-process element, in solar-metallicity stars. Our algorithm compares LTE synthetic spectra with high-resolution observational spectra using a χ 2 -minimization routine. The analysis is fully automated, and therefore allows consistent measure- ment of blended lines even across very large stellar samples. We compare our results with literature europium abundance measurements and find them to be consistent; we also find that our method generates smaller errors. Every atom heavier than lithium has been processed by stars. Elements of the α-process, iron peak, and r-process have dif- ferent formation sites, and therefore, understanding the dis- tribution of these elements in nearby stars can lead to a better understanding of the Galaxy's chemical enrichment history. The r-process site is the least well understood. Europium (Eu) is our choice for an r-process investigation for two reasons: 96% of Galactic europium is formed through the r-process (Burris et al. 2000), and it has several strong lines in the visible portion of the electromagnetic spectrum. In order to provide insight into the Galactic enrichment history, however, europium measurements
Electron correlation effects and magnetic ordering at the Gd(0001) surface

Effects of electron correlation on the electronic structure and magnetic properties of the Gd(0001) surface are investigated using the full-potential linearized augmented plane-wave implementation of correlated band theory (``LDA+U''). The use of LDA+U instead of LDA (local-density approximation) total-energy calculations produces the correct ferromagnetic ground state for both bulk Gd and the Gd surface. Surface strain relaxation leads to a 90% enhancement of the interlayer surface-to-bulk effective exchange coupling. Application of a Landau-Ginzburg-type theory yields a 30% enhancement of the Curie temperature at the surface, in very good agreement with the experiment.
Baby ears: a recognition system for affective vocalizations

Our goal was to see how much of the affective message we could recover using simple acoustic measures of the speech signal. Using pitch and broad spectral-shape measures, a multidimensional Gaussian mixture-model discriminator classified adult-directed (neutral affect) versus infant-directed speech correctly more than 80% of the time, and classified the affective message of infant-directed speech correctly nearly 70% of the time. We confirmed previous findings that changes in pitch provide an important cue for affective messages. In addition, we found that timbre or cepstral coefficients also provide important information about the affective message. Mothers' speech was significantly easier to classify than fathers' speech, suggesting either clearer distinctions among these messages in mothers' speech to infants, or a difference between fathers and mothers in the acoustic information used to convey these messages. Our research is a step towards machines that sense the "emotional state" of a speaker.
Ion temperature and density relationships measured by CINDI from the C/NOFS spacecraft during solar minimum

[1] The Ion Velocity Meter (IVM), a part of the CINDI instrument package on board the C/NOFS spacecraft, makes in situ measurements of plasma temperature, composition, density, and velocity. The 16 April 2008 launch of C/NOFS coincided with the deepest solar minimum since the space age began with F10.7 cm radio fluxes in the 60–70 solar flux unit range. Because of the 13° inclination of the orbit the location of the perigee advances through all local times in about 66 days. This allows seasonal sampling of ionospheric temperature, density, and composition as a function of local time, magnetic latitude, and altitude. Measurements taken near the spacecraft's 402 km perigee altitude indicate an unusually cold low-density ionosphere with nighttime ion temperatures at the magnetic equator reaching as low as 600 K with an [O+]/[H+] ratio of 4 and maximum daytime temperatures of 1300 K. The O+ to H+ transition height is very low and at the highest altitudes measured H+ comprises over 75% of the ionospheric plasma at all local times. We compare average values of the measured parameters with those from the International Reference Ionosphere and with incoherent scatter radar measurements from Jicamarca.
Transfer matrix for treating stratified media including birefringent crystals

Birefringent crystals are extensively used to manipulate polarized light. The generalized transfer matrix developed allows efficient calculation of the full polarization state of light transmitted through and reflected by a stack of arbitrarily many discrete layers of isotropic and birefringent materials at any frequency and angle of incidence. The matrix of a uniaxial birefringent crystal with arbitrary rotation is calculated, along with its reduction to the matrix of an isotropic medium. This method is of great practical importance where tight control of systematic effects is needed in optical systems employing birefringent crystals, one example being wave plates used by cosmic microwave background polarimetry with wide field-of-view telescopes.
Deconvolution of noisy transient signals: A Kalman filtering application

The deconvolution of transient signals from noisy measurements is a common problem occuring in various tests at Lawrence Livermore National Laboratory. The transient deconvolution problem places atypical constraints on algorithms presently available. The Schmidt-Kalman filter, a time-varying, tunable predictor, is designed using a piecewise constant model of the transient input signal. A simulation is developed to test the algorithm for various input signal bandwidths and different signal-to-noise ratios for the input and output sequences. The algorithm performance is reasonable.
On Free Baxter Algebras: Completions and the Internal Construction

We continue the study of free Baxter algebras. There are two goals of this paper. The first goal is to extend the construction of shuffle Baxter algebras to completions of Baxter algebras. This process is motivated by a construction of Cartier and is analogous to the process of completing a polynomial algebra to obtain a power series algebra. However, as we will see later, unlike the close similarity of properties of a polynomial algebra and a power series algebra, properties of a shuffle Baxter algebra and its completion can be quite different.
Highly effective actions

It is conjectured that the world-volume action of a probe D3-brane in an AdS_5 × S^5 background of type IIB superstring theory, with one unit of flux, can be reinterpreted as the exact effective action (or highly effective action) for U(2) N = 4 super Yang-Mills theory on the Coulomb branch. An analogous conjecture for U(2)_k × U(2)_(−k) ABJM theory is also presented. The main evidence supporting these conjectures is that the brane actions have all of the expected symmetries and dualities. Highly effective actions have general coordinate invariance, even though they describe nongravitational theories.
Simplification of network dynamics in large systems

We show that when networks are large significant simplicity can be achieved for pricing-based control. We first consider a general loss network with Poisson arrivals and arbitrary holding time distributions. In dynamic pricing schemes, the network provider can charge different prices to the user according to the current utilization level of the network and also other factors. We show that when the system becomes large the performance (in terms of expected revenue) of an appropriately chosen static pricing scheme, whose price is independent of the current network utilization, will approach that of the optimal dynamic pricing scheme. Further, we show that under certain conditions, this static price is independent of the route that the flows take. We then extend the result to the case of dynamic routing, and show that the performance of an appropriately chosen static pricing scheme with bifurcation probability determined by average parameters can also approach that of the optimal dynamic routing scheme when the system is large. These results deepen our understanding of pricing-based network control. In particular, they provide us with the insight that, when the system is large, an appropriate pricing strategy based on the average network conditions (hence, slowly changing) can approach optimality.
Results of some recent hydrofoil work

shown between the measured flap data and aerodynamic theory. It is shown that the vectorial addition of the separate effects of fixed flaps in waves and driven flaps in smooth water is in close correlation with results for cycling flaps in waves. It is substantiated for supercavitating design that the Tulin two-term section has a greater lift-to-drag ratio than a flat wedge section at a given lift coefficient, and good flap effectiveness is obtained on supercavitating foils. Data at cavitation number zero agree with accepted theory.
Stability Analysis and Testing of a Train of Centrifugal Compressors for High Pressure Gas Injection

This paper describes the rotor dynamic stability analysis and the PTC-10 Class 1 test of a three body centrifugal compressor train for high pressure natural gas injection service. This train had a full load full pressure string test on hydrocarbon gasses to a final discharge pressure of 500 BAR (7250 PSIA). Each compressor is of the back to back configuration, and is equipped with tilting pad seals, damper bearings, and a honeycomb labyrinth at the division wall with shunt holes. The driver is a gas turbine.
On Differential Rota-Baxter Algebras

Abstract A Rota–Baxter operator of weight λ is an abstraction of both the integral operator (when λ = 0 ) and the summation operator (when λ = 1 ). We similarly define a differential operator of weight λ that includes both the differential operator (when λ = 0 ) and the difference operator (when λ = 1 ). We further consider an algebraic structure with both a differential operator of weight λ and a Rota–Baxter operator of weight λ that are related in the same way that the differential operator and the integral operator are related by the First Fundamental Theorem of Calculus. We construct free objects in the corresponding categories. In the commutative case, the free objects are given in terms of generalized shuffles, called mixable shuffles. In the noncommutative case, the free objects are given in terms of angularly decorated rooted forests. As a byproduct, we obtain structures of a differential algebra on decorated and undecorated planar rooted forests.
Interactions between dissolved organic matter and mercury in the Florida Everglades

Experiments were conducted using organic matter isolated from various surface waters in the Florida Everglades to study the interactions between dissolved organic matter (DOM) and Hg(II). Conditional distribution coefficients (K DOM' ), obtained using an equilibrium dialysis ligand exchange method, were strongly affected by the Hg/DOM concentration ratio. Very strong interactions (K DOM' =10 23.2±0.5 L/kg), indicative of Hg-thiol bonds, were observed at Hg/DOM ratios below approximately 1 μgHg/mgDOM. Above approximately 10 μgHg/mgDOM much lower K DOM ' values (10 10.7±0.5 L/kg) were obtained. DOM-Hg interactions were also studied by HgS (log(K sp )=-52.4) dissolution and precipitation experiments. In the dissolution experiments, a significant amount of Hg was released from cinnabar in the presence of DOM, suggesting strong interactions. Conversely, precipitation of HgS was strongly inhibited in the presence of low concentrations (≤3 mgC/L) of DOM. In both the dissolution and precipitation experiments, organic matter rich in aromatic moieties was more reactive with HgS than less aromatic fractions and sulfur-containing model compounds. These results suggest that DOM can influence the geochemistry of inorganic complexes of Hg in the Everglades, especially HgS, by strong Hg-DOM binding and colloidal stabilization.
Electron-Spin Beat Susceptibility of Excitons in Semiconductor Quantum Wells

Recent time-resolved differential transmission and Faraday rotation measurements of long-lived electron-spin coherence in quantum wells displayed intriguing parametric dependencies. For their understanding we formulate a microscopic theory of the optical response of a gas of optically incoherent excitons whose constituent electrons retain spin coherence, under a weak magnetic field applied in the quantum well's plane. We define a spin beat susceptibility and evaluate it in linear order of the exciton density. Our results explain the many-body physics underlying the basic features observed in the experimental measurements.
Virasoro constraints and the Chern classes of the Hodge bundle

Abstract We analyse the consequences of the Virasoro conjecture of Eguchi, Hori and Xiong for Gromov-Witten invariants, in the case of zero degree maps to the manifolds P 1 and P 2 (or more generally, smooth projective curves and smooth simply connected projective surfaces). We obtain predictions involving intersections of psi and lambda classes on M g,n . In particular, we show that the Virasoro conjecture for P 2 implies the numerical part of Faber's conjecture on the tautological Chow ring of Mg.
Comparison of low-energy lunar transfer trajectories to invariant manifolds

In this study, transfer trajectories from the Earth to the Moon that encounter the Moon at various flight path angles are examined, and lunar approach trajectories are compared to the invariant manifolds of selected unstable orbits in the circular restricted three-body problem. Previous work focused on lunar impact and landing trajectories encountering the Moon normal to the surface, and this research extends the problem with different flight path angles in three dimensions. The lunar landing geometry for a range of Jacobi constants is computed, and approaches to the Moon via invariant manifolds from unstable orbits are analyzed for different energy levels.
First demonstration of a free-electron laser driven by electrons from a laser-irradiated photocathode

We report the results from the first operation of a free electron laser (FEL) driven by an electron beam from a laser-irradiated photocathode. The Rocketdyne/Stanford FEL achieved sustained oscillations, lasting in excess of three hours, driven by photoelectrons accelerated by the Stanford Mark III radiofrequency linac. A LaB6 cathode, irradiated by a tripled Nd: Yag mode-locked drive laser was the source of photoelectrons. The drive laser, operating at 95.2 MHz, was phase-locked to the 30th subharmonic of the S-band linac. Peak currents in excess of 125 A were observed and delivered to the Rocketdyne 2 m undulator which was operated as a stand-alone oscillator. Sustainable small-signal gain of 100% per pass was observed over a 2 h time period with periodic observation of small-signal gain as high as 150% per pass. Preliminary estimates of the electron-beam brightness deliverable to the undulator range from 3.5 × 1011 to 5.0 × 1011 A/(rad m)2.
D1D5 system and noncommutative geometry

Supergravity on AdS3×S3×T4 has a dual description as a conformal sigma-model with the target space being the moduli space of instantons on the noncommutative torus. We derive the precise relation between the parameters of this noncommutative torus and the parameters of the near-horizon geometry. We show that the low energy dynamics of the system of D1D5-branes wrapped on the torus of finite size is described in terms of the noncommutative geometry. As a byproduct, we give a prediction on the dependence of the moduli space of instantons on the noncommutative T4 on the metric and the noncommutativity parameter. We give a compelling evidence that the moduli space of stringy instantons on R4 with the B-field does not receive α′-corrections. We also study the relation between the D1D5 sigma-model instantons and the supergravity instantons.
Hollow-fiber, Evanescent Light-wave, Atom-bottle Trap

Recent theoretical and experimental demonstrations have shown that blue-detuned laser light, propagating in the annular core-cladding region of a hollow-glass fiber, produces a repulsive, evanescent light-wave potential in the hollow that can be used to guide near-resonant atoms down the fiber.1–4 In this work I show that slight modifications to the hollow-fiber geometry can be used to turn this atom guide into an atom-bottle trap.5-6 The trap can be opened and shut by varying the aperture angle at which light couples into the fiber, allowing the atoms to be easily loaded. This trap has an advantage over other optical atom traps in that the atoms move coherently in a field-free region with only brief specular reflections at the step-like potential walls.
Benefit of Delay on the Diversity-Multiplexing Tradeoffs of MIMO Channels with Partial CSI

This paper re-examines the well-known fundamental tradeoffs between rate and reliability for the multi-antenna, block Rayleigh fading channel in the high signal to noise ratio (SNR) regime when (i) the transmitter has access to (noiseless) one bit per coherence-interval of causal channel state information (CSI) and (it) soft decoding delays together with worst-case delay guarantees are acceptable. A key finding of this work is that substantial improvements in reliability can be realized with a very short expected delay and a slightly longer (but bounded) worst-case decoding delay guarantee in communication systems where the transmitter has access to even one bit per coherence interval of causal CSI. While similar in spirit to the recent work on communication systems based on automatic repeat requests (ARQ) where decoding failure is known at the transmitter and leads to re-transmission, here transmit side-information is purely based on CSI. The findings reported here also lend further support to an emerging understanding that decoding delay (related to throughput) and codeword blocklength (related to coding complexity and delays) are distinctly different design parameters which can be tuned to control reliability.
The aeronomy of odd nitrogen in the thermosphere 2. Twilight emissions

A model developed for the aeronomy of odd nitrogen in the thermosphere is used to analyze rocket measurements of N(4S) and NO densities. Data from Atmosphere Explorer were used to develop a consistent reaction kinetics model for odd nitrogen chemistry. It is concluded that most NO(+) dissociative recombination events must produce N(2D), that N(2D) is quenched by O at a rate of 1 trillionth cu cm per sec, and that the atmospheric O2 quenching rate of N(2D) is consistent with the laboratory rate. The major quenching agent of N(2D) between 140 and 220 km is atomic oxygen, and this reaction is the major source of N(4S). Peak N(4S) densities of about (20-60) million per cu cm at 140-150 km are predicted, with the variability being indicative of the model sensitivity to a factor of 2 change in the O/O2 ratio in the thermosphere.
Three Dimensional Characteristics of Turbulent Wakes Behind Rotors of Axial Flow Turbomachinery

Analytical and experimental investigations of the characteristics of three-dimensional turbulent wakes downstream of a turbomachinery rotor are reported in this paper. An approximate quasi-three-dimensional turbulent wake model for turbomachinery rotor is developed and compared with the cascade and isolated airfoil wake models. The rotor wake model is capable of predicting the decay of mean component of radial and streamwise velocities as a function of rotor geometry, speed of rotation, and the turbulence properties of the flow field. A rotation parameter based on similarity analysis is derived. The velocity profiles in both the radial and cylindrical planes are coupled together. Measurement of mean velocities (Un , Us , Ur ), turbulent intensities and stresses (un2, us2, ur2, usun, unur, usur) is carried out using a triple sensor hot wire probe in a stationary system at various axial and radial locations downstream of the rotor. Profiles of mean and turbulent quantities are obtained. Semi-theoretical expressions for the decay rates of the defect in mean velocity, turbulence intensity, and Reynolds stress (maximum values) with distance downstream of the rotor are derived. The experimental data on the rotor wake are compared with that of an isolated airfoil and cascade of airfoils. The investigation suggests that rotor wake decays much faster than the cascade or an isolated airfoil wake.
Simple geodesics on a punctured surface

Abstract We give a new proof of McShane's Theorem [G. McShane, Simple geodesics and a series constant over Teichmuller space, Invent. Math. 132 (3) (1998) 607–632], using simple equivariant methods in the hyperbolic plane.
Mutual coherence of polarized light in disordered media: two-frequency method extended

The paper addresses the two-point correlations of electromagnetic waves in general random, bi-anisotropic media whose constitutive tensors are complex Hermitian, positive- or negative-definite matrices. A simplified version of the two-frequency Wigner distribution (2f-WD) for polarized waves is introduced and the closed form Wigner–Moyal equation is derived from the Maxwell equations. In the weak-disorder regime with anarbitrarily varying background the two-frequency radiative transfer (2f-RT) equations for the associated 2 × 2 coherence matrices are derived from the Wigner–Moyal equation by using the multiple-scale expansion. In birefringent media, the coherence matrix becomes a scalar and the 2f-RT equations take the scalar form due to the absence of depolarization. A paraxial approximation is developed for spatially anisotropic media. Examples of isotropic, chiral, uniaxial and gyrotropic media are discussed.
Stabilization, Syndication, and Pricing of IPOs

We argue that in the after-market trading of an IPO, the underwriting syndicate, by standing ready to buy back shares at the offer price ("price stabilization"), compensates uninformed investors ex post for the adverse selection cost they face in bidding for IPOs. This domi? nates ex ante compensation by underpricing. The reason is that stabilization exploits ex post information about investor demand whereas underpricing must be based on ex ante infor? mation. However, liquidity and syndication costs constrain the use of stabilization which, in equilibrium, generates some underpricing as well. We develop a model that formalizes this intuition and generates several empirical implications.
The Role of Infrastructure in the Rural - Urban Digital Divide

A significant gap exists in the percentage of rural and urban households that connect to the Internet. Furthermore, this "digital divide" has been increasing with respect to high-speed connections. The primary course of action to address this emerging high-speed digital divide has been to subsidize digital communications technology (DCT) infrastructure. This paper explores the diffusion of DCT infrastructure in both rural and urban areas over the period 2000 - 2003, and estimates its contribution to the emerging divide in high-speed access. The findings suggest that the rural - urban high-speed divide is more strongly associated with differences in household characteristics like education and income than differences in infrastructure.