cssi/SciSciGPT-SciSciNet huggingface dataset:
Compressed sensing with sparse binary matrices: Instance optimal error guarantees in near-optimal time

A compressed sensing method consists of a rectangular measurement matrix, [email protected]?R^m^x^N with [email protected]?N, together with an associated recovery algorithm, A:R^m->R^N. Compressed sensing methods aim to construct a high quality approximation to any given input vector [email protected]?R^N using only [email protected]?R^m as input. In particular, we focus herein on instance optimal nonlinear approximation error bounds for M and A of the form @?x-A(Mx)@?"[email protected][email protected]?x-x"k^o^p^[email protected]?"p+Ck^1^/^p^-^1^/^[email protected]?x-x"k^o^p^[email protected]?"q for [email protected]?R^N, where x"k^o^p^t is the best possible k-term approximation to x. In this paper we develop a compressed sensing method whose associated recovery algorithm, A, runs in O((klogk)logN)-time, matching a lower bound up to a O(logk) factor. This runtime is obtained by using a new class of sparse binary compressed sensing matrices of near optimal size in combination with sublinear-time recovery techniques motivated by sketching algorithms for high-volume data streams. The new class of matrices is constructed by randomly subsampling rows from well-chosen incoherent matrix constructions which already have a sub-linear number of rows. As a consequence, fewer random bits than previously required are needed in order to select the rows utilized by the fast reconstruction algorithms considered herein.
Coarse structures and group actions

The main results of the paper are: \begin{Prop}\label{GenSvarc-Milnor} A group $G$ acting coarsely on a coarse space $(X,\CC)$ induces a coarse equivalence $g\to g\cdot x_0$ from $G$ to $X$ for any $x_0\in X$. \end{Prop} Theorem: \label{GenGromovThm} Two coarse structures $\CC_1$ and $\CC_2$ on the same set $X$ are equivalent if the following conditions are satisfied: \begin{enumerate} \item Bounded sets in $\CC_1$ are identical with bounded sets in $\CC_2$, \item There is a coarse action $\phi_1$ of a group $G_1$ on $(X,\CC_1)$ and a coarse action $\phi_2$ of a group $G_2$ on $(X,\CC_2)$ such that $\phi_1$ commutes with $\phi_2$. \end{enumerate} They generalize the following two basic results of coarse geometry: Proposition: [\v{S}varc-Milnor Lemma {\cite[Theorem 1.18]{Roe lectures}}] \label{Svarc-Milnor} A group $G$ acting properly and cocompactly via isometries on a length space $X$ is finitely generated and induces a quasi-isometry equivalence $g\to g\cdot x_0$ from $G$ to $X$ for any $x_0\in X$. Theorem: [Gromov {\cite[page 6]{Gro asym invar}}] \label{GromovThm} Two finitely generated groups $G$ and $H$ are quasi-isometric if and only if there is a locally compact space $X$ admitting proper and cocompact actions of both $G$ and $H$ that commute.
Comments on Color-Suppressed Hadronic B Decays

Abstract Recent experimental results on the color-suppressed nonleptonic decays B 0 →D (∗)0 π 0 provide evidence for a failure of the naive factorization model and for sizeable relative strong-interaction phases between class-1 and class-2 B →D (∗) π decay amplitudes. The allowed regions for the corresponding ratios of (complex) isospin amplitudes and a2/a1 parameters are determined. The results are interpreted in the context of QCD factorization for the related class-1 amplitudes in the heavy-quark limit.
Is There Enhanced Depletion of Gas-Phase Nitrogen in Moderately Reddened Lines of Sight?

We report on the abundance of interstellar neutral nitrogen (N I) for 30 sight lines, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope (HST). N I column densities are derived by measuring the equivalent widths of several ultraviolet absorption lines and subsequently fitting those to a curve of growth. We find a mean interstellar N/H of 51 ± 4 ppm. This is below the mean found by Meyer et al. of 62 ppm (adjusted for a difference in f-values). Our mean N/H is similar, however, to the (f-value adjusted) mean of 51 ± 3 ppm found by Knauth et al. for a larger sample of sight lines with larger hydrogen column densities comparable to those in this study. We discuss the question of whether or not nitrogen shows increased gas-phase depletion in lines of sight with column densities log N(Htot) 21, as claimed by Knauth et al. The nitrogen abundance in the line of sight toward HD 152236 is particularly interesting. We derive very small N/H and N/O ratios for this line of sight that may support a previous suggestion that members of the Sco OB1 association formed from an N-deficient region.
Epimerization of cyanocobalamin. Improved synthesis of cyano-8-epicobalamin and its characterization by x-ray crystallography, and 1H, 13C, and 15N NMR

Abstract The structure of cyano-8-epicobalamin (CN-8-epiCbl), the C8 epimer of vitamin B12 (cyanocobalamin, CNCbl) has been determined by X-ray crystallography, complete assignment of its 1H and 13C NMR spectra, as well as observation and assignment of its amide 1H and 15N NMR spectra in DMSO-d6. This compound was previously reported as the poorly characterized product of the amidation of its c-monocarboxylate, obtained as a minor product of the borohydride reduction of cobalamin-c-lactone. The conditions for the key epimerization step have now been changed to provide a tripling of the yield of the 8-epi-c-monocarboxylate. Along with substantial improvement in the procedures for synthesizing cobalamin-c-lactone and for amidating the monocarboxylate, this modified method for epimerization of cyanocobalamin now provides CN-8-epiCbl in sufficient quantities for thorough characterization and studies of its properties as a vitamin B12 analog. The crystal structure of CN-8-epiCbl has been determined. The main difference between the crystal structure of CNCbl and CN-8-epiCbl is that the d side chain (at C8) is “down-wardly” axial in CNCbl, but pseudo-equatorial in CN-8-epiCbl. In addition, the B pyrrole ring in CN-8-epiCbl is twisted by about 5°, the axial benzimidazole moiety is tilled about 7° toward the A and D rings, and the corrin macrocycle fold angle along the Co … C10 axis (23.8°) is more severe than that in CNCbl (17.7°). Fourteen water molecules are well located in the crystal structure and four others occur at half-occupancy. The epimeric relationship between CN-8-epiCbl and CNCbl and the configuration at C8 are also evident in observed 1H NMR nuclear Overhauser enhancements and differences in amide 1H and 15N chemical shifts at the d amide between CNCbl and CN-8-epiCbl. Measurements of the amide proton chemical shift thermal gradients strongly suggest the presence of a hydrogen bond in CN-8-epiCbl involving the c amide syn proton and the d amide carbonyl in solution. This intramolecular hydrogen bonding is not present in the crystal structure in which the d amide carbonyl is hydrogen bonded to two water molecules and the c amide nitrogen is hydrogen bonded to the b amide carbonyl oxygen of a symmetry related molecule. Comparison of the 13C spectra of CNCbl and CN-8-epiCbl shows that significant chemical shift changes are not restricted to the B ring (the site of epimerization) but are more global in nature, reflecting the changes in corrin ring conformation.
Sharp probability estimates for generalized Smirnov statistics

We give sharp, uniform estimates for the probability that the empirical distribution function for n uniform-[0,1] random variables stays to one side of a given line.
Palladium-Catalyzed Asymmetric Alkylation in the Synthesis of Cyclopentanoid and Cycloheptanoid Core Structures Bearing All-Carbon Quaternary Stereocenters

General catalytic asymmetric routes toward cyclopentanoid and cycloheptanoid core structures embedded in numerous natural products have been developed. The central stereoselective transformation in our divergent strategies is the enantioselective decarboxylative alkylation of seven-membered β-ketoesters to form α-quaternary vinylogous esters. Recognition of the unusual reactivity of β-hydroxyketones resulting from the addition of hydride or organometallic reagents enabled divergent access to γ-quaternary acylcyclopentenes through a ring contraction pathway or γ-quaternary cycloheptenones through a carbonyl transposition pathway. Synthetic applications of these compounds were explored through the preparation of mono-, bi-, and tricyclic derivatives that can serve as valuable intermediates for the total synthesis of complex natural products. This work complements our previous work with cyclohexanoid systems.
Promising Developments in Computer-Assisted Instruction

The work in computer-assisted instruction conducted at Stanford is reviewed in the context of developmental stages through which the CAI programs have passed, and the next step in the evolution of these programs is discussed. Areas that might be well suited to computer-assisted instruction also are mentioned, and systems now moving in these directions are described. Our experiences in teacher training and coordinating computer-assisted instruction with classroom instruction are reviewed.
Some exact computations on the twisted butterfly state in string field theory

The twisted butterfly state solves the equation of motion of vacuum string field theory in the singular limit. The finiteness of the energy density of the solution is an important issue, but possible conformal anomaly resulting from the twisting has prevented us from addressing this problem. We present a description of the twisted regulated butterfly state in terms of a conformal field theory with a vanishing central charge which consists of the ordinary bc ghosts and a matter system with c = 26. Various quantities relevant to vacuum string field theory are computed exactly using this description. We find that the energy density of the solution can be finite in the limit, but the finiteness depends on the subleading structure of vacuum string field theory. We further argue, contrary to our previous expectation, that contributions from subleading terms in the kinetic term to the energy density can be of the same order as the contribution from the leading term which consists of the midpoint ghost insertion.
A Model for Star Formation, Gas Flows, and Chemical Evolution in Galaxies at High Redshifts

Motivated by the increasing use of the Kennicutt-Schmidt (K-S) star formation law to interpret observations of high-redshift galaxies, the importance of gas accretion to galaxy formation, and the recent observations of chemical abundances in galaxies at -->z ~ 2-3, I use simple analytical models to assess the consistency of these processes of galaxy evolution with observations and with each other. I derive the time dependence of star formation implied by the K-S law and show that the sustained high star formation rates observed in galaxies at -->z ~ 2-3 require the accretion of additional gas. A model in which the gas accretion rate is approximately equal to the combined star formation and outflow rates broadly reproduces the observed trends of star formation rate with galaxy age. Using an analytical description of chemical evolution, I also show that this model, further constrained to have an outflow rate roughly equal to the star formation rate, reproduces the observed mass-metallicity relation at -->z ~ 2.
Two EM-type channel estimation algorithms for OFDM with transmitter diversity

We study channel estimation for orthogonal frequency-division multiplexing (OFDM) systems utilizing transmitter diversity and operating over multipath fading channels. Two expectation-maximization (EM)-type algorithms are introduced and compared with each other in terms of convergence rate. At each iteration and for every OFDM link, the EM-type algorithms partition the problem of estimating a multi-input channel into independent channel estimations for each transmit-receive antenna pair, therefore avoiding the matrix inversion encountered in the joint least-square estimation. The EM-type algorithms can also be used to efficiently implement a recently proposed algorithm, termed the significant-tap-catching estimator, so that the system performance is more robust to different multipath channel delay profiles.
High order parametrized maximum-principle-preserving and positivity-preserving WENO schemes on unstructured meshes

In this paper, we generalize the maximum-principle-preserving (MPP) flux limiting technique developed by Xu (2013) 20 to a class of high order finite volume weighted essentially non-oscillatory (WENO) schemes for scalar conservation laws and the compressible Euler system on unstructured meshes in one and two dimensions. The key idea of this parameterized limiting technique is to limit the high order numerical flux with a first order flux which preserves the MPP or positivity-preserving (PP) property. The main purpose of this paper is to investigate the flux limiting approach with high order finite volume method on unstructured meshes which are often needed for solving some important problems on irregular domains. Truncation error analysis based on one-dimensional nonuniform meshes is presented to justify that the proposed MPP schemes can maintain third order accuracy in space and time. We also demonstrate through smooth test problems that the proposed third order MPP/PP WENO schemes coupled with a third order Runge-Kutta (RK) method attain the desired order of accuracy. Several test problems containing strong shocks and complex domain geometries are also presented to assess the performance of the schemes.
Synthesis of N4-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-l-asparagine analogues. n-Butyramide, 3-chloropropionamide, 3-aminopropionamide, and isovaleramide analogues

Abstract The syntheses of four analogues of N 4 -(2-acetamido-2-deoxy-β- d -glucopyranosyl)- l -asparagine are described. Activated carboxylic acids were reacted with 2-acetamido-2-deoxy-β- d -glucopyranosylamine. n -Butyric anhydride gave N -(2-acetamido-2-deoxy-β- d -glucopyranosyl)- n -butyramide. 3-Chloropropionic anhydride was synthesized from 3-chloropropionic acid and gave N -(2-acetamido-2-deoxy-β- d -glucopyranosyl)-3-chloropropionamide. Equilibration of the latter with ammonium bicarbonate gave N 1 -(2-acetamido-2-deoxy-β- d -glucopyranosyl)-3-aminopropionamide. Succinimidyl isovalerate was synthesized and gave N -(2-acetamido-2-deoxy-β- d -glucopyranosyl)isovaleramide.
Recent Progress in the Electrochemical Conversion and Utilization of CO2

Over the past several years, there has been a growing interest in the capture of carbon dioxide emissions and either their permanent immobilization or chemical conversion to industrially relevant products. Several processes have been developed and studied; however, many of these methods are quite expensive since they require either ultra high purity CO2 or are energy intensive. Also, many purely chemical methods show low product selectivity. To address these limitations, several researchers have initiated activities using electrochemical processes to increase reaction pathway selectivity and reduce cost since it allows for direct control of the surface free energy through the electrode potential, which has shown promise. This review article focuses on the advantages and disadvantages of current electrochemical, photoelectrochemical and bioelectrochemical processes for CO2 conversion, and future directions for research in this area are discussed.
Synchrotron Radiation as the Source of Gamma-Ray Burst Spectra

We investigate synchrotron emission models as the source of gamma-ray burst (GRB) spectra. We show that including the possibility for synchrotron self-absorption, a "smooth cutoff" to the electron energy distribution, and an anisotropic distribution for the electron pitch angles produces a whole range of low-energy spectral behavior. In addition, we show that the procedure of spectral fitting to GRB data over a finite bandwidth can introduce a spurious correlation between spectral parameters—in particular, the value of the peak of the νFν spectrum, Ep, and the low-energy photon spectral index α (the lower Ep is, the lower [softer] the fitted value of α will be). From this correlation and knowledge of the Ep distribution, we show how to derive the expected distribution of α. We show that optically thin synchrotron models with an isotropic electron pitch angle distribution can explain the distribution of α below α = - . This agreement is achieved if we relax the unrealistic assumption of the presence of a sharp low-energy cutoff in the spectrum of accelerated electrons and allow for a more gradual break. We show that this low-energy portion of the electron spectrum can be at most flat. We also show that optically thin synchrotron models with an anisotropic electron pitch angle distribution can explain all bursts with - α 0. The very few bursts with low-energy spectral indices that fall above α = 0 may be due to the presence of a synchrotron self-absorption frequency entering the lower end of the BATSE window. Our results also predict a particular relationship between α and Ep during the temporal evolution of a GRB. We give examples of spectral evolution in GRBs and discuss how its behavior is consistent with the above models.
Samarium Diiodide Mediated Reactions in Total Synthesis

Introduced by Henri Kagan more than three decades ago, samarium diiodide (SmI 2 ) has found increasing application in chemical synthesis. This single-electron reducing agent has been particularly useful in C-C bond formations, including those found in total synthesis endeavors. This Review highlights selected applications of SmI 2 in total synthesis, with special emphasis on novel transformations and mechanistic considerations. The examples discussed are both illus- trative of the power of this reagent in the construction of complex molecules and inspirational for the design of synthetic strategies toward such targets, both natural and designed.
Teaching geomorphology through spreadsheet modelling

Abstract Geomorphology, like most scientific disciplines, has evolved from a descriptive stage through quantification to modelling of processes and outcomes. Indeed, high-resolution modelling has been termed the “third branch of science” for its ability to generate high-quality hypotheses, testable in turn through field mapping and laboratory experimentation. I teach the principles and basic applications of modelling using microcomputer spreadsheets. These serve as “transparent boxes” in which graphical output is generated in response to numerical input, and more importantly, in which the modeler (student) can see the equations and order of steps (unlike traditional “black box” models). The technology is widely available and familiarity with it can be assumed, required, or taught at the undergraduate level. Modelling can be taught through a series of spreadsheet exercises in which students, while learning topical material in a traditional sequence, progress from a simple, “cookbook” exercise through more realistic, process-based exercises to the level of addressing a previously unstudied research question. At each step the model can be used to generate testable hypotheses. I have worked with scarp evolution, stream longitudinal profiles, and glacier reconstructions, and plan to include eolian, soil development, mass wasting, and coastal processes in additional exercises. The first year of use of this technique in a junior-level Geomorphology course clarified the strengths and weaknesses of the modelling approach. The strengths involve students learning the capabilities and flaws of modelling, a stronger understanding of causeeffect relationships, and the effects of time on landforms. The weaknesses involve time commitment, supervision in model implementation, and limitations to student ability to independently pursue openended research.
Fast continuous collision detection among deformable models using graphics processors

We present an interactive algorithm to perform continuous collision detection between general deformable models using graphics processors (GPUs). We model the motion of each object in the environment as a continuous path and check for collisions along the paths. Our algorithm precomputes the chromatic decomposition for each object and uses visibility queries on GPUs to quickly compute potentially colliding sets of primitives. We introduce a primitive classification technique to perform efficient continuous self-collision. We have implemented our algorithm on a 3.0GHz Pentium IV PC with a NVIDIA 7800GPU, and we highlight its performance on complex simulations composed of several thousands of triangles. In practice, our algorithm is able to detect all contacts, including self-collisions, at image-space precision in tens of milli-seconds.
Qualifying and Keeping Your Employees Qualified: How Hard Can That Be?

What constitutes a qualified employee? In the Occupational Safety and Health Administration's (OSHA's) eyes, will five, ten, or 15 years of experience; licenses; certifications; or a degree make an employee qualified? Licenses, certifications, degrees, and other types of technical experience do not qualify a worker to perform tasks on or near exposed energized circuit parts. Every worker who is expected to work on or near exposed energized circuits must be properly trained to meet OSHA's requirements. OSHA's definition of a qualified person includes not only the technical skills and knowledge but also the ability to recognize and avoid electrical hazards and understand the construction, installation, and operation of the equipment involved. In addition, the employee must demonstrate those skills and knowledge. Is there a simple way to comply? This article will explore one method a company used to comply with OSHA's requirement.
Oceanic tracer and proxy time scales revisited

Abstract. Quantifying time-responses of the ocean to tracer input is important to the interpretation of paleodata from sediment cores – because surface-injected tracers do not instantaneously spread throughout the ocean. To obtain insights into the time response, a computationally efficient state-transition matrix method is demonstrated and used to compute successive states of passive tracer concentrations in the global ocean. Times to equilibrium exceed a thousand years for regions of the global ocean outside of the injection and convective areas and concentration gradients give time-lags from hundreds to thousands of years between the Atlantic and Pacific abyss, depending on the injection region and the nature of the boundary conditions employed. Equilibrium times can be much longer than radiocarbon ages – both because the latter are strongly biased towards the youngest fraction of fluid captured in a sample, and because they represent distinct physical properties. Use of different boundary conditions – concentration, or flux – produces varying response times, with the latter depending directly upon pulse duration. With pulses, the sometimes very different transient approach to equilibrium in various parts of the ocean generates event identification problems.
Three looks at instantons in F-theory — New insights from anomaly inflow, string junctions and heterotic duality

We discuss the physics of zero modes of ED3/M5 instantons at strong coupling from three different viewpoints. Motivated by an anomaly inflow argument, we give a prescription for describing neutral instanton modes in terms of string junctions, unifying the language with that used for charged modes. We proceed to discuss the physics of charged modes as we move between different points in the moduli space of F-theory compactified on K3. In particular, we show how, in going from the $ E_6^3 $ point to the SO(8)4 point, the structure of SO(8) zero modes arises from a non-trivial mixing of massless 27’s of E 6 with massive modes stretching between different E 6 stacks. We observe a similar mixing in going from SO(8)4 to $ E_6^3 $ . Finally, we see how the zeroes of some exact worldsheet instanton superpotentials in heterotic backgrounds preserving E 6 symmetry admit a physical interpretation in terms of low energy physics. We also discuss the behavior of the dual F-theory compactification as the superpotential approaches a zero. An interesting observation is that in the examples we study some of the zeroes of the superpotential correspond to points of E 8 enhancement in the worldvolume of the dual M5 instanton, and more generally from enhancements of the singularity over the worldvolume of the instanton.
Delay Decomposition at a Single Server queue with Constant Service Time and Multiple Inputs

Two networks consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivaleneies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self delay and interference delay.
Exploring the design space of mixed swing quadrail for low-power digital circuits

This paper describes and explores the design space of a mixed voltage swing methodology for lowering the energy per switching operation of digital circuits in standard submicron complementary metal-oxide-semiconductor (CMOS) fabrication processes. Employing mixed voltage swings expands the degrees of freedom available in the power-delay optimization space of static CMOS circuits. In order to study this design space and evaluate the power-delay tradeoffs, analytical polynomial formulations for power and delay of mixed swing circuits are derived and HSPICE simulation results are presented to demonstrate their accuracy. Efficient voltage scaling and transistor sizing techniques based on our analytical formulations are proposed for optimizing energy/operation subject to target delay constraints; up to 2.2/spl times/ improvement in energy/operation is demonstrated for an ISCAS'85 benchmark circuit using these techniques. Experimental results from HSPICE simulations and measurements from an And-Or-Invert (AO1222) test chip fabricated in the Hewlett-Packard 0.5 /spl mu/m process are presented to demonstrate up to 2,92/spl times/ energy/operation savings for optimized mixed swing circuits compared to static CMOS.
An agent-based decision support system for electric vehicle charging infrastructure deployment

The current scarcity of public charging infrastructure is one of the major barriers to mass household adoption of electric vehicles (EVs). Many drivers are reluctant to purchase EVs without convenient charging access away from home, but investors are also hesitant to build charging stations without underlying knowledge of EV demand realization. In this paper, an agent-based decision support system is presented for identifying patterns in residential EV ownership and driving activities to enable strategic deployment of new charging infrastructure. The Chicagoland area is used as a case study to demonstrate the model.
Discrete shape sensitivity equations for aerodynamic problems

Intensive research and development in Computational Fluid Dynamics (CFD) has recently produced many powerful CFD codes to simulate complex aerodynamic phenomena. However, in order to enhance the usefulness of these CFD codes for design practice, development of design sensitivity equations compatible to these codes becomes very important. This paper represents a part of such an effort to develop a sensitivity analysis methodology that enables the sensitivity equations to be implemented into existing CFD codes with minimal code modification. The methodology is based upon a preelimination procedure which accounts for consistently linearized boundary conditions. Formulations of both the direct differentiation and the adjoint variable methods will be presented in the paper.
Nasdaq Trading and Trading Costs: 1993-2002

Nasdaq spreads decline from 1993 to 2002, largely independently of tick-size reductions. Trade size declines, consistent with greater retail investor activity. Using the method of Chordia, Roll, and Subrahmanyam (2001), we find that concurrent market returns strongly affect liquidity and trading activity. Liquidity exhibits distinct day-of-the-week patterns. There is little evidence that macroeconomic announcements or changes in key interest rates affect Nasdaq stocks overall; but in the bear market, we find a relation between some of these variables and effective spreads, which we interpret as consistent with Nasdaq participants’ paying greater attention to fundamentals after the market crash.
Right-convergence of sparse random graphs

The paper is devoted to the problem of establishing right-convergence of sparse random graphs. This concerns the convergence of the logarithm of number of homomorphisms from graphs or hyper-graphs \(\mathbb{G }_N, N\ge 1\) to some target graph \(W\). The theory of dense graph convergence, including random dense graphs, is now well understood (Borgs et al. in Ann Math 176:151–219, 2012; Borgs et al. in Adv Math 219:1801–1851, 2008; Chatterjee and Varadhan in Eur J Comb 32:1000–1017, 2011; Lovasz and Szegedy in J Comb Theory Ser B 96:933–957, 2006), but its counterpart for sparse random graphs presents some fundamental difficulties. Phrased in the statistical physics terminology, the issue is the existence of the limits of appropriately normalized log-partition functions, also known as free energy limits, for the Gibbs distribution associated with \(W\). In this paper we prove that the sequence of sparse Erdos-Renyi graphs is right-converging when the tensor product associated with the target graph \(W\) satisfies a certain convexity property. We treat the case of discrete and continuous target graphs \(W\). The latter case allows us to prove a special case of Talagrand’s recent conjecture [more accurately stated as level III Research Problem 6.7.2 in his recent book (Talagrand in Mean Field Models for Spin Glasses: Volume I: Basic examples. Springer, Berlin, 2010)], concerning the existence of the limit of the measure of a set obtained from \(\mathbb{R }^N\) by intersecting it with linearly in \(N\) many subsets, generated according to some common probability law. Our proof is based on the interpolation technique, introduced first by Guerra and Toninelli (Commun Math Phys 230:71–79, 2002) and developed further in (Abbe and Montanari in On the concentration of the number of solutions of random satisfiability formulas, 2013; Bayati et al. in Ann Probab Conference version in Proceedings of 42nd Ann. Symposium on the Theory of Computing (STOC), 2010; Contucci et al. in Antiferromagnetic Potts model on the Erdos-Renyi random graph, 2011; Franz and Leone in J Stat Phys 111(3/4):535–564, 2003; Franz et al. in J Phys A Math Gen 36:10967–10985, 2003; Montanari in IEEE Trans Inf Theory 51(9):3221–3246, 2005; Panchenko and Talagrand in Probab Theory Relat Fields 130:312–336, 2004). Specifically, Bayati et al. (Ann Probab Conference version in Proceedings of 42nd Ann. Symposium on the Theory of Computing (STOC), 2010) establishes the right-convergence property for Erdos-Renyi graphs for some special cases of \(W\). In this paper most of the results in Bayati et al. (Ann Probab Conference version in Proceedings of 42nd Ann. Symposium on the Theory of Computing (STOC), 2010) follow as a special case of our main theorem.
High-Temperature Performance of Cast CF8C-Plus Austenitic Stainless Steel

Covers and casings of small to medium size gas turbines can be made from cast austenitic stainless steels, including grades such as CF8C, CF3M, or CF10M. Oak Ridge National Laboratory and Caterpillar have developed a new cast austenitic stainless steel, CF8C-Plus, which is a fully austenitic stainless steel, based on additions of Mn and N to the standard Nb-stabilized CF8C steel grade. The Mn addition improves castability, as well as increases the alloy solubility for N, and both Mn and N synergistically act to boost mechanical properties. CF8C-Plus steel has outstanding creep-resistance at 600-900 C, which compares well with Ni-based superalloys such as alloys X, 625, 617, and 230. CF8C-Plus also has very good fatigue and thermal fatigue resistance. It is used in the as-cast condition, with no additional heat-treatments. While commercial success for CF8C-Plus has been mainly for diesel exhaust components, this steel can also be considered for gas turbine and microturbine casings. The purposes of this paper are to demonstrate some of the mechanical properties, to update the long-term creep-rupture data, and to present new data on the high-temperature oxidation behavior of these materials, particularly in the presence of water vapor.
Stratospheric observatory for infrared astronomy (SOFIA)

Abstract The joint U.S. and German SOFIA project to develop and operate a 2.5-meter infrared airborne telescope in a Boeing 747-SP is now well into development. First science flights will begin in 2004 with 20% of the observing time assigned to German investigators. The observatory is expected to operate for over 20 years. The sensitivity, characteristics and science instrument complement are discussed. SOFIA will have instrumentation that will allow astronomical surveys that were not possible on the KAO. A future SOFIA survey project related to astrochemistry is discussed.
Small molecule activation at uranium coordination complexes: control of reactivity via molecular architecture.

Electron-rich uranium coordination complexes display a pronounced reactivity toward small molecules. In this Feature article, the exciting chemistry of trivalent uranium ions coordinated to classic Werner-type ligand environments is reviewed. Three fundamentally important reactions of the [((RArO)3tacn)U]-system are presented that result in alkane coordination, CO/CO2 activation, and nitrogen atom-transfer chemistry.
Identifying aspects for web-search queries

Many web-search queries serve as the beginning of an exploration of an unknown space of information, rather than looking for a specific web page. To answer such queries effectively, the search engine should attempt to organize the space of relevant information in a way that facilitates exploration. We describe the ASPECTOR system that computes aspects for a given query. Each aspect is a set of search queries that together represent a distinct information need relevant to the original search query. To serve as an effective means to explore the space, ASPECTOR computes aspects that are orthogonal to each other and to have high combined coverage. ASPECTOR combines two sources of information to compute aspects. We discover candidate aspects by analyzing query logs, and cluster them to eliminate redundancies. We then use a mass-collaboration knowledge base (e.g., Wikipedia) to compute candidate aspects for queries that occur less frequently and to group together aspects that are likely to be "semantically" related. We present a user study that indicates that the aspects we compute are rated favorably against three competing alternatives - related searches proposed by Google, cluster labels assigned by the Clusty search engine, and navigational searches proposed by Bing.
Two-color interferometry using a detuned frequency-doubling crystal.

Phase mismatch by angular detuning permits continuous variation of the intensity of second-harmonic light generated in a nonlinear crystal while maintaining a controlled phase relationship between the first and second harmonics. Interference of this second-harmonic light with second-harmonic light generated in a second crystal was measured and can be understood by taking beam walk-off into account. When the second crystal is replaced by a fiber, the phase of the χ(2) grating in the fiber is measured to be 88 ± 4°, which differs by 180° from recently reported results.
The mystery of the brane relation

Using the notion of surgery on objects called Y-graphs and claspers by Goussarov and Habiro, one can define a theory of finite type invariants of closed 3-manifolds. The paper discusses upper bounds for the number of invariants, and focuses on two surprises that arise: One surprise is that the upper bounds depend on a bit more than a choice of generators for H1. A complementary surprise a curious brane relation (in two flavors, open and closed) which shows that the upper bounds are in a certain sense independent of the choice of generators of H1.
Product differentiation and duration of US import trade

We examine the extent to which product differentiation affects duration of US import trade relationships. The results are consistent with a matching model of trade formation. Using highly disaggregated product level data we estimate the hazard rate is at least 23% higher for homogeneous goods than for differentiated products. The results are not only highly robust but are often strengthened under alternative specifications. As the smallest relationships are dropped, differences across product types increase. Controlling for potential measurement errors also results in larger differences across product types.
Integral Polyhedra in Three Space

In a series of recent papers I have introduced a particular class of convex polyhedra in Rn, arising in the study of integer programming problems with n variables. In the present paper a detailed analysis of these polyhedra will be given for the case in which n = 3; the analysis is based on an unpublished theorem demonstrated several years ago by Roger Howe, which seems to have no immediate generalization to higher values of n.
A short proof that “proper = unit”

Abstract A short proof is given that the graphs with proper interval representations are the same as the graphs with unit interval representations.
Forwarding, backstepping, and finite spectrum assignment for time delay systems

The nonlinear control ideas and results of forwarding and backstepping have been recently extended to systems with time delay. In this paper we discuss how to apply these tools to design robust controls for linear delay systems. We first show that the integral cross-term forwarding produces a feedback law that achieves finite spectrum of the closed loop system. Combining it with backstepping provides a structured design method for a large class of systems with time delay. Robustness of the controller to uncertainties, including uncertain time delay, is illustrated by an example.
SPITZER AND z′ SECONDARY ECLIPSE OBSERVATIONS OF THE HIGHLY IRRADIATED TRANSITING BROWN DWARF KELT-1b

We present secondary eclipse observations of the highly irradiated transiting brown dwarf KELT-1b. These observations represent the first constraints on the atmospheric dynamics of a highly irradiated brown dwarf, the atmospheres of irradiated giant planets at high surface gravity, and the atmospheres of brown dwarfs that are dominated by external, rather than internal, energy. Using the Spitzer Space Telescope, we measure secondary eclipse depths of 0.195% ± 0.010% at 3.6 μm and 0.200% ± 0.012% at 4.5 μm. We also find tentative evidence for the secondary eclipse in the z' band with a depth of 0.049% ± 0.023%. These measured eclipse depths are most consistent with an atmosphere model in which there is a strong substellar hotspot, implying that heat redistribution in the atmosphere of KELT-1b is low. While models with a more mild hotspot or even with dayside heat redistribution are only marginally disfavored, models with complete heat redistribution are strongly ruled out. The eclipse depths also prefer an atmosphere with no TiO inversion layer, although a model with TiO inversion is permitted in the dayside heat redistribution case, and we consider the possibility of a day-night TiO cold trap in this object. For the first time, we compare the IRAC colors of brown dwarfs and hot Jupiters as a function of effective temperature. Importantly, our measurements reveal that KELT-1b has a [3.6] – [4.5] color of 0.07 ± 0.11, identical to that of isolated brown dwarfs of similarly high temperature. In contrast, hot Jupiters generally show redder [3.6] – [4.5] colors of ~0.4, with a very large range from ~0 to ~1. Evidently, despite being more similar to hot Jupiters than to isolated brown dwarfs in terms of external forcing of the atmosphere by stellar insolation, KELT-1b appears to have an atmosphere most like that of other brown dwarfs. This suggests that surface gravity is very important in controlling the atmospheric systems of substellar mass bodies.
Synthesis of carbohydrate-based antibiotics

Tackling the problem of carbohydrate recognition is a subject of current interest. Our strategies in this regard include development of new methods for the synthesis of sac- charides and sugar arrays for screening, design of D-peptides to target bacterial cell-surface sugars, preparation of mechanism-based inhibitors of the enzymes involved in the biosyn- thesis of saccharides and the synthesis of aminoglycoside mimetics to target RNA.
A 10 GHz Y-Ba-Cu-O/GaAs hybrid oscillator proximity coupled to a circular microstrip patch antenna

A 10-GHz hybrid Y-Ba-Cu-O/GaAs microwave oscillator proximity coupled to a circular microstrip antenna has been designed, fabricated, and characterized. The oscillator was a reflection mode type using a GaAs MESFET as the active element. The feedline, transmission lines, RF chokes, and bias lines were all fabricated from YBa/sub 2/Cu/sub 3/O/sub 7-x/ superconducting thin films on a 1-cm*1-cm lanthanum aluminate substrate. The output feedline of the oscillator was wire bonded to a superconducting feedline on a second 1 cm*1 cm lanthanum aluminate substrate, which was in turn proximity coupled to a circular microstrip patch antenna. Antenna patterns from this active patch antenna and the performance of the oscillator measured at 77 K are reported. The oscillator had a maximum output power of 11.5 dBm at 77 K, which corresponded to an efficiency of 10%. In addition, the efficiency of the microstrip patch antenna together with its high temperature superconducting feedline was measured from 85 K to 30 K and was found to be 71% at 77 K, increasing to a maximum of 87.4% at 30 K. >
Rational approach to selective and direct 2-O-alkylation of 5,6-O-isopropylidine-L-ascorbic acid

l-Ascorbic acid is a versatile radical scavenger widely distributed in aerobic organisms that plays a central role in the protection of cellular components against oxidative damage by free radicals and oxidants. It also functions as a physiological reductant for key enzymatic transformations in catecholamine neurotransmitters, amidated peptide hormones, and collagen biosynthetic pathways. Simple derivatives of l-ascorbic acid have been shown to possess antioxidant, antitumor, and immunostimulant activities. The antioxidant and redox properties of l-ascorbic acid are closely associated with the electron-rich 2,3-enediol moiety of the molecule, and therefore, selective functionalization of the 2- and 3-OH groups is essential for the detailed structure-activity studies. Reactions of 5- and 6-OH-protected ascorbic acid with electrophilic reagents exclusively produce the corresponding 3-O-alkylated products under mild basic conditions due to the high nucleophilicity of the C-3-OH. Based on the density functional theory (B3LYP) electron density calculations, we have devised a novel and general method for the direct alkylation of the 2-OH group of ascorbic acid with complete regio- and chemoselectivity. We have also carried out a complete spectroscopic analysis of two complementary series of 2-O-acetyl-3-O-alkyl- and 2-O-alkyl-3-O-acetylascorbic acid derivatives to define their spectroscopic characteristics and to resolve common inconsistencies in the literature.
Efficient Diacetoxylation of Alkenes via Pd(II)/Pd(IV) Process with Peracetic Acid and Acetic Anhydride

A palladium-catalyzed diacetoxylation of alkenes in the presence of peracetic acid and acetic anhydride was developed to produce diacetates efficiently and diastereoselectively. Due to its mild conditions, this method was suitable for a broad range of substrates encompassing conjugated and nonconjugated olefins.
Co-simulation of algebraically coupled dynamic subsystems

This paper analyzes the problem of co-simulation. The term co-simulation is used to describe a large dynamic system that is simulated by running a group of independently coded subsystem simulators. Very commonly, the co-simulation of subsystems faces incompatible boundary conditions, i.e., causal conflicts. These causal conflicts cannot be directly resolved, due to the nonlinearity and/or difficulties in modification of coded subsystem simulators. Causal conflicts result in algebraic constraints. Boundary condition coordinators (BCC) are designed to calculate boundary conditions based on subsystem models and their algebraic constraints. The co-simulation, which is modeled as differential algebraic equations, then relies on BCC to provide compatible boundary conditions for subsystem simulators. The high index constraint is reduced to index one by defining a sliding manifold. Different ways of enforcing the sliding manifold are discussed: A new discrete-time sliding mode (DTSM) controller is devised to serve as a BCC, enforcing sliding manifolds and providing boundary conditions. The multirate scheme can guarantee co-simulation stability at any given step size of all subsystem simulators, provided the subsystem simulators are tested stable at that step size. An example is given to demonstrate the DTSM method Advantages and possible future improvements are also discussed.
Local properties of patterned vegetation: quantifying endogenous and exogenous effects

Dryland ecosystems commonly exhibit periodic bands of vegetation, thought to form due to competition between individual plants for heterogeneously distributed water. In this paper, we develop a Fourier method for locally identifying the pattern wavenumber and orientation, and apply it to aerial images from a region of vegetation patterning near Fort Stockton, TX, USA. We find that the local pattern wavelength and orientation are typically coherent, but exhibit both rapid and gradual variation driven by changes in hillslope gradient and orientation, the potential for water accumulation, or soil type. Endogenous pattern dynamics, when simulated for spatially homogeneous topographic and vegetation conditions, predict pattern properties that are much less variable than the orientation and wavelength observed in natural systems. Our local pattern analysis, combined with ancillary datasets describing soil and topographic variation, highlights a largely unexplored correlation between soil depth, pattern coherence, vegetation cover and pattern wavelength. It also, surprisingly, suggests that downslope accumulation of water may play a role in changing vegetation pattern properties.
One loop scattering on D-branes

We analyze one-loop scattering amplitudes of the massless states on a stack of D3-branes. We use the vertex operators that have been obtained in the direct open string analysis developed in arXiv:0708.3452. The method does not have the obstacle of the D9 computation which is associated with the appearance of an e-tensor. The divergence structure is not the same as the D9-brane case. What makes the analysis deviate from the D9-brane case is that the momenta of the states have non-zero components only along the brane directions. We ponder on the possibility that the one-loop divergence may be canceled by adding additional vertex operators at the tree level. We anticipate that they will be “exponentiated” to the free string action, with the resulting action to constitute a non-linear sigma model of the D-brane/AdS geometry.