cssi/SciSciGPT-SciSciNet huggingface dataset:
An alternating direction method with increasing penalty for stable principal component pursuit

The stable principal component pursuit (SPCP) is a non-smooth convex optimization problem, the solution of which enables one to reliably recover the low rank and sparse components of a data matrix which is corrupted by a dense noise matrix, even when only a fraction of data entries are observable. In this paper, we propose a new algorithm for solving SPCP. The proposed algorithm is a modification of the alternating direction method of multipliers (ADMM) where we use an increasing sequence of penalty parameters instead of a fixed penalty. The algorithm is based on partial variable splitting and works directly with the non-smooth objective function. We show that both primal and dual iterate sequences converge under mild conditions on the sequence of penalty parameters. To the best of our knowledge, this is the first convergence result for a variable penalty ADMM when penalties are not bounded, the objective function is non-smooth and its sub-differential is not uniformly bounded. Using partial variable splitting and adopting an increasing sequence of penalty multipliers, together, significantly reduce the number of iterations required to achieve feasibility in practice. Our preliminary computational tests show that the proposed algorithm works very well in practice, and outperforms ASALM, a state of the art ADMM algorithm for the SPCP problem with a constant penalty parameter.
Metal cooling in simulations of cosmic structure formation

The addition of metals to any gas can significantly alter its evolution by increasing the rate of radiative cooling. In star-forming environments, enhanced cooling can potentially lead to fragmentation and the formation of low-mass stars, where metal-free gas-clouds have been shown not to fragment. Adding metal cooling to numerical simulations has traditionally required a choice between speed and accuracy. We introduce a method that uses the sophisticated chemical network of the photoionization software, CLOUDY, to include radiative cooling from a complete set of metals up to atomic number 30 (Zn) that can be used with large-scale three-dimensional hydrodynamic simulations. Our method is valid over an extremely large temperature range (10 ≤ T ≤ 10 8 K), up to hydrogen number densities of 10 12 cm -3 . At this density, a sphere of 1 M ⊙ has a radius of roughly 40 au. We implement our method in the adaptive mesh refinement hydrodynamic/N-body code, ENZO. Using cooling rates generated with this method, we study the physical conditions that led to the transition from Population III to Population II star formation. While C, O, Fe and Si have been previously shown to make the strongest contribution to the cooling in low-metallicity gas, we find that up to 40 per cent of the metal cooling comes from fine-structure emission by S, when solar abundance patterns are present. At metallicities, Z ≥ 10 -4 Z ⊙ , regions of density and temperature exist where gas is both thermally unstable and has a cooling time less than its dynamical time. We identify these doubly unstable regions as the most inducive to fragmentation. At high redshifts, the cosmic microwave background inhibits efficient cooling at low temperatures and, thus, reduces the size of the doubly unstable regions, making fragmentation more difficult.
Tropical hyperelliptic curves

We study the locus of tropical hyperelliptic curves inside the moduli space of tropical curves of genus g. We define a harmonic morphism of metric graphs and prove that a metric graph is hyperelliptic if and only if it admits a harmonic morphism of degree 2 to a metric tree. This generalizes the work of Baker and Norine on combinatorial graphs to the metric case. We then prove that the locus of 2-edge-connected genus g tropical hyperelliptic curves is a (2g?1)-dimensional stacky polyhedral fan whose maximal cells are in bijection with trees on g?1 vertices with maximum valence 3. Finally, we show that the Berkovich skeleton of a classical hyperelliptic plane curve satisfying a certain tropical smoothness condition is a standard ladder of genus g.
THE RISK ASSOCIATED WITH RENAL DYSFUNCTION IN CHRONIC HEART FAILURE IS RESTRICTED PRIMARILY TO PATIENTS WITH NEUROHORMONAL ACTIVATION

Renal dysfunction (RD) is a potent prognostic indicator in patients with heart failure. Notably, an elevated blood urea nitrogen to creatinine ratio (BUN/Creat) identifies a particularly high risk phenotype of RD, which may be due to the fact that elevated BUN/Creat is a surrogate for renal
Monopoles and the Chiral Phase Transition In SU(2) Lattice Gauge Theory

Abstract In the quenched approximation we use the abelian and monopole fields from abelian projection in SU(2) lattice gauge theory to numerically compute the value of the chiral condensate. The condensate calculated using abelian projection is observed to vanish at the same critical temperature as the full SU(2) theory predicts.
Changing the heights of automorphism towers

Abstract If G is a centreless group, then τ(G) denotes the height of the automorphism tower of G . We prove that it is consistent that for every cardinal λ and every ordinal α , there exists a centreless group G such that (a) τ(G)=α ; and (b) if β is any ordinal such that 1⩽β , then there exists a notion of forcing P , which preserves cofinalities and cardinalities, such that τ(G)=β in the corresponding generic extension V P .
The chronic effects of concussion on gait

Abstract Martini DN, Sabin MJ, DePesa SA, Leal EW, Negrete TN, Sosnoff JJ, Broglio SP. The chronic effects of concussion on gait. Objective To examine the effects of concussion on gait patterns of young adults with and without a history of concussion during single- and dual-task paradigms. Design Cross-sectional evaluation. Setting A research laboratory. Participants Persons with (n=28; mean, 6.32y postinjury) and without (n=40) a concussion history. Intervention Not applicable. Main Outcome Measures A battery of gait analyses during single- and dual-task conditions. Normalized velocity, step length, stride width, number correct from cognitive task, time in single-leg stance, and time in double-leg stance were the variables of interest. Gait was analyzed using an electronic walkway system, and the Brooks visuospatial cognitive task was used to index cognition. Results Data analyses using multiple 2-way repeated-measures analyses of variance and correlations indicated that participants with a history of concussion spent significantly more time in a double-leg stance and significantly decreased time in a single-leg stance and had slower gait velocity. There also was a significant negative correlation between number of concussions and time in single-leg stance and positive correlations between number of concussions and time in double-leg stance and double-stance percent. Conclusion These findings suggest that persons with a history of concussion adopt a more conservative gait strategy.
Ambipolar Diffusion Heating in Turbulent Systems

The temperature of the gas in molecular clouds is a key determinant of the characteristic mass of star formation. Ambipolar diffusion (AD) is considered one of the most important heating mechanisms in weakly ionized molecular clouds. In this work, we study the AD heating rate using two-fluid turbulence simulations and compare it with the overall heating rate due to turbulent dissipation. We find that for observed molecular clouds, which typically have Alfven Mach numbers of ~1 and AD Reynolds numbers of ~20, about 70% of the total turbulent dissipation is in the form of AD heating. AD has an important effect on the length scale where energy is dissipated: when AD heating is strong, most of the energy in the cascade is removed by ion-neutral drift, with a comparatively small amount of energy making it down to small scales. We derive a relation for the AD heating rate that describes the results of our simulations to within a factor of two. Turbulent dissipation, including AD heating, is generally less important than cosmic-ray heating in molecular clouds, although there is substantial scatter in both.
A nearly model-independent characterization of dark energy properties as a function of redshift

Understanding the acceleration of the universe and its cause is one of the key problems in physics and cosmology today, and is best studied using a variety of mutually complementary approaches. Daly and Djorgovski (2003, 2004) proposed a model independent approach to determine the expansion and acceleration history of the universe and a number of important physical parameters of the dark energy as functions of redshift directly from the data. Here, we apply the method to explicitly determine the first and second derivatives of the coordinate distance with respect to redshift, y' and y", and combine them to solve for the kinetic and potential energy density of the dark energy as functions of redshift, K(z) and V(z). A data set of 228 supernova and 20 radio galaxy measurements with redshifts from zero to 1.79 is used for this study. Values of y' and y" are combined to study the dimensionless acceleration rate of the universe as a function of redshift, q(z). The only assumptions underlying our determination of q(z) are that the universe is described by a Robertson-Walker (RW) metric and is spatially flat. We find that the universe is accelerating today, and was decelerating in the recent past. The transition from acceleration to deceleration occurs at a redshift of about Z_T = 0.42 ± ^(0.08)_(0.06). Values of y' and y" are combined to determine K(z) and V(z). These are shown to be consistent with the values expected in a standard Lambda Cold Dark Matter (LCDM) model.
Deflection Of Light By Using Tungsten Bronze Crystals

This paper reports our preliminary results on an electrooptical light deflector for streak camera applications that uses tungsten bronze SBN:60% crystals. We found the performance of these ferroelectric crystals to be an order of magnitude better than the best LiNbO3 crystals currently available. We discuss the theory and performance of this crystal as well as other bronze crystals for application to the streak camera.
Continental Basalts and Mantle Xenoliths

In this decade of the International Lithosphere Program, much scientific attention is being directed toward the deep continental crust and subadjacent mantle. The petrologic, geochemical, and isotopic signatures of basaltic magmas, which transect much of the lithosphere as they ascend from their site of melting, and of contained cognate and accidental xenoliths, which are found along the path of ascent, give us, perhaps, the best clues to composition and structure in the third dimension. Continental Basalts and Mantle Xenoliths provides an opportunity to sample the British school of thought on subjects such as differences between oceanic and continental basalts, effects of mantle metasomatism, and relationships between events in the subcontinental mantle and those in the overlying crust. This volume is recommended by the publisher as being of interest to senior undergraduates and postgraduate researchers; I would extend that readership to all scientists who seek access to a potpourri of recent findings and current ideas in a rapidly evolving field of research.
Low-Cost Learning via Active Data Procurement

We design mechanisms for online procurement of data held by strategic agents for machine learning tasks. We study a model in which agents cannot fabricate data, but may lie about their cost of furnishing their data. The challenge is to use past data to actively price future data in order to obtain learning guarantees, even when agents' costs can depend arbitrarily on the data itself. We show how to convert a large class of no-regret algorithms into online posted-price and learning mechanisms. Our results parallel classic sample complexity guarantees, but with the key resource constraint being money rather than quantity of data available. With a budget constraint B, we give robust risk (predictive error) bounds on the order of 1/√B. In many cases our guarantees are significantly better due to an active-learning approach that leverages correlations between costs and data. Our algorithms and analysis go through a model of no-regret learning with T arriving pairs (cost, data) and a budget constraint of B, coupled with the "online to batch conversion". Our regret bounds for this model are on the order of T/√B and we give lower bounds on the same order.
Catalytic enantioselective synthesis of macrolides via asymmetric alkylation

Abstract Catalytic enantioselective syntheses of the macrolides ( R )-(−) phoracantholide and ( R )-(+) lasiodiplodin have been achieved. Stereochemistry was introduced in using an arene chromium tricarbonyl derived catalyst, which mediated the enantioselective addition of dimethyl zinc to a functionalized aldehyde.
Track Segment Association for Ground Moving Targets with Evasive Move-Stop-Move Maneuvers

In a real tracking system, track breakages can occur due to highly maneuvering targets, low detection probability, or clutter. Previously, a track segment association approach (TSA) was developed for an airborne early warning (AEW) system to improve track continuity by"stitching" broken track segments pertaining to the same target. However, this technique cannot provide satisfactory association performance in tracking with a GMTI radar ground moving targets employing evasive move-stop-move maneuvers. To avoid detection by a GMTI radar, targets can deliberately stop for some time before moving again. Since a GMTI radar does not detect a target when the radial velocity (along the line-of-sight from the sensor) falls below a certain minimum detectable velocity (MDV), the move-stop-move maneuvers of the targets usually lead to broken tracks as a result. We present a new TSA technique which employs a dummy track to formulate a complete association. By using an IMM estimator with state-dependent mode transition probabilities (IMM-SDP) for track segment prediction (forward and backward), the proposed algorithm can effectively stitch both "regular" broken tracks and broken tracks due to targets' move-stop-move maneuvers. Comparisons are given to show the advantages of the proposed algorithm in broken tracks reduction and track continuity improvement.
History and Action: The Inter-American Human Rights System and the Role of the Inter-American Commission on Human Rights

This article examines the historical origins of the Inter-American human rights system and key achievements of the Inter-American Commission on Human Rights over the past fifty years. It explores the Commission’s use of on sight visits and country reports to expose human rights violations of military governments during the 1970s and its increased use of the case system since the restoration of democratic rule in the 1990s. The article also notes how shifts in US foreign policy toward the region impacted the Commission’s work. It concludes by noting certain obstacles and challenges currently faced by the Commission.
Microsaccades and blinks trigger illusory rotation in the Rotating Snakes illusion

Certain repetitive arrangements of luminance gradients elicit the perception of strong illusory motion. Among them, the "Rotating Snakes Illusion" has generated a large amount of interest in the visual neurosciences, as well as in the public. Prior evidence indicates that the Rotating Snakes illusion depends critically on eye movements, yet the specific eye movement types involved and their associated neural mechanisms remain controversial. According to recent reports, slow ocular drift--a nonsaccadic type of fixational eye movement--drives the illusion, whereas microsaccades produced during attempted fixation fail to do so. Here, we asked human subjects to indicate the presence or absence of rotation during the observation of the illusion while we simultaneously recorded their eye movements with high precision. We found a strong quantitative link between microsaccade and blink production and illusory rotation. These results suggest that transient oculomotor events such as microsaccades, saccades, and blinks, rather than continuous drift, act to trigger the illusory motion in the Rotating Snakes illusion.
Durable Goods Monopoly, Buyer Uncertainty, and Concurrent Selling and Renting

Stylized durable goods monopoly models typically conclude that monopolists prefer to rent their output due to commitment problems associated with sales. However, we commonly observe monopolistic firms in durable goods industries simultaneously selling and renting output. To address this apparent discrepancy a simple two-period asymmetric information model is constructed where buyers are uncertain of the good's durability and the firm's manufacturing costs. This is a natural asymmetric information specification since the firm typically has more precise knowledge of product durability and production costs than buyers do. The analysis indicates that a monopolist may wish to concurrently sell and rent output when buyers do not have perfect knowledge. If, for example, consumers believe that product durability and manufacturing costs are higher than they truly are, the firm may wish to simultaneously sell and rent output. Thus buyers' expectations about firm costs and product durability are of critical importance in durable goods models, particularly in terms of explaining concurrent rentals and sales.
Smoothness Priors and Nonlinear Regression

Abstract Smoothness priors represent prior information that an unknown function does not change slope quickly and hence that the function describes a simple curve (e.g., Wahba 1978). In this article such priors for the multiple nonlinear regression model are developed in such a way that estimates and “standard errors” can be obtained as a natural and conceptually straightforward extension of linear multiple-regression estimation with the addition of dummy variables and dummy observations. Relations to spline and polynomial interpolation are described. An illustrative example of cost-function estimation is provided.
Design, preparation, and implementation of an imidazole-based chiral biaryl P,N-ligand for asymmetric catalysis.

A new strategy for increasing the barrier to rotation in biaryls has been developed that allows for the incorporation of 5-membered aromatic heterocycles into chiral atropisomers. Using this concept, an imidazole-based biaryl P,N-ligand has been designed and prepared as a single enantiomer. This ligand performs exceptionally well in the enantioselective A3-coupling, demonstrating the potential of this new design element.
Centrally symmetric manifolds with few vertices

Abstract A centrally symmetric 2 d -vertex combinatorial triangulation of the product of spheres S i × S d − 2 − i is constructed for all pairs of nonnegative integers i and d with 0 ⩽ i ⩽ d − 2 . For the case of i = d − 2 − i , the existence of such a triangulation was conjectured by Sparla. The constructed complex admits a vertex-transitive action by a group of order 4 d . The crux of this construction is a definition of a certain full-dimensional subcomplex, B ( i , d ) , of the boundary complex of the d -dimensional cross-polytope. This complex B ( i , d ) is a combinatorial manifold with boundary and its boundary provides a required triangulation of S i × S d − i − 2 . Enumerative characteristics of B ( i , d ) and its boundary, and connections to another conjecture of Sparla are also discussed.
Risk assessment of scramjet unstart using adjoint-based sampling methods

We demonstrate an adjoint based approach for accelerating Monte Carlo estimation of risk, and apply it to estimating the probability of unstart in a SCRamjet engine under uncertain conditions that are characterized by various Gaussian and non-Gaussian distributions. The adjoint equation is solved with respect to an objective function that is used to identify unstart and the adjoint solution is used to generate a linear approximation to the objective function. This linear surrogate is used to divide the uncertain input parameters into three different strata, corresponding to safe operation of the engine, uncertain operation and unstart. The probability of unstart within these strata is very different and as a result, stratified sampling significantly increases the efficiency of the risk assessment procedure by reducing the variance of the estimator. Using this technique, the Monte Carlo method was demonstrated to be accelerated by a factor of 5.4.
The benefits of allowing heteroscedastic stochastic distributions in multiple discrete-continuous choice models

This paper investigates the benefits of incorporating heteroscedastic stochastic distributions in random utility maximization-based multiple discrete-continuous (MDC) choice models. To this end, first, a Multiple Discrete-Continuous Heteroscedastic Extreme Value (MDCHEV) model is formulated to allow heteroscedastic extreme value stochastic distributions in MDC models. Next, an empirical analysis of individuals' daily time use choices is carried out using data from the National Household Travel Survey (NHTS) for three geographical regions in Florida. A variety of different MDC model structures are estimated: (a) the Multiple Discrete-Continuous Extreme Value (MDCEV) model with independent and identically distributed (IID) extreme value error structure, (b) the MDCHEV model, (c) the mixed-MDCEV model that allows heteroscedasticity by mixing a heteroscedastic distribution over an IID extreme value kernel, (d) the MDC generalized extreme value (MDCGEV) model that allows inter-alternative correlations using the multivariate extreme value error structure, (e) the mixed-MDCEV model that allows inter-alternative correlations using common mixing distributions across choice alternatives, and (f) the mixed-MDCEV model that allows both heteroscedasticity and inter-alternative correlations. Among all these model structures, the MDCHEV model provided the best fit to the current empirical data. Further, heteroscedasticity was prominent while no significant inter-alternative correlations were found. Specifically, the MDCHEV parameter estimates revealed the significant presence of heteroscedasticity in the random utility components of different activity type choice alternatives. On the other hand, the MDCEV model resulted in inferior model fit and systematic discrepancies between the observed and predicted distributions of time allocations, which can be traced to the thick right tail of the type-1 extreme value distribution. The MDCHEV model addressed these issues to a considerable extent by allowing tighter stochastic distributions for certain choice alternatives, thanks to its accommodation of heteroscedasticity among random utility components. Furthermore, spatial transferability assessments using different transferability metrics also suggest that the MDCHEV model clearly outperformed the MDCEV model.
Estimation and prediction in the random effects model with AR(p) remainder disturbances

Abstract This paper considers the problem of estimation and forecasting in a panel data model with random individual effects and AR( p ) remainder disturbances. It utilizes a simple exact transformation for the AR( p ) time series process derived by Baltagi and Li (1994) and obtains the generalized least squares estimator for this panel model as a least squares regression. This exact transformation is also used in conjunction with Goldberger’s (1962) result to derive an analytic expression for the best linear unbiased predictor. The performance of this predictor is investigated using Monte Carlo experiments and illustrated using an empirical example.
Screening for Anticancer Agents from Sonoran Desert Plants:A Chemical Ecology Approach

This study evaluates the potential benefits of using ecology-based theories of plant chemical defense when screening plants for pharmaceutical activity. Extracts from 63 Sonoran Desert plant species representing 26 families were screened in microtiter/optical density–based assays against a cervix epithelial carcinoma cell line (HeLa) and mouse fibroblast cells (3T3). In HeLa cytotoxicity assays, 34 of 63 species (54%) showed significant inhibitory effects. Nine of these active extracts were significantly less toxic to a noncancerous mouse fibroblast cell line (3T3) and, thus, showed potentially cancer specific activity. Using the plant apparency/predictability hypothesis as a theoretical basis, this study used plant growth habit (e.g., annual, herbaceous perennial, woody perennial, evergreen) as an indicator of plant predictability, and hence likelihood of having well-established chemical defenses. This approach led to predictions that may be useful in locating plant species that produce biologically acti...
Performance characteristics of phased array and thinned aperture optical telescopes

While phased telescope arrays for general-purpose broadband imaging applications suffer severe sensitivity losses and field-of-view limitations, thinned-aperture telescopes consisting of a dilute, segmented primary mirror with a common secondary mirror are viable second-generation space telescope configurational possibilities yielding resolution and sensitivity an order of magnitude greater than those of the Hubble Space Telescope. Attention is given to thinned-aperture optical systems' image quality characterization problems; the 'practical resolution limit' image quality criterion proposed is defined as the reciprocal of the spatial frequency within which no zeros occur in the modulation transfer function.
Signatures of Molecular Magnetism in Single-Molecule Transport Spectroscopy

We report single-molecule-transistor measurements on devices incorporating magnetic molecules. By studying the electron-tunneling spectrum as a function of magnetic field, we are able to identify signatures of magnetic states and their associated magnetic anisotropy. A comparison of the data to simulations also suggests that sequential electron tunneling may enhance the magnetic relaxation of the magnetic molecule.
Letters of James Anthony Froude

This article is the fourth and last by Bennent in which he edits Froude's Letters in the Library's Theodore Stanton collection. There are 29 letters in total in this series. The letters here are from Froude to Stanton written between 1888 and 1894 and are replies to Stanton's requests for Froude to contribute articles to Stanton's various publications.
Efficient Algorithms for Privately Releasing Marginals via Convex Relaxations

Differential privacy is a definition giving a strong privacy guarantee even in the presence of auxiliary information. In this work, we pursue the application of geometric techniques for achieving differential privacy, a highly promising line of work initiated by Hardt and Talwar (Proceedings of the 42nd ACM Symposium on Theory of Computing, STOC'10, pp 705---714. ACM Press, New York, 2010). We apply these techniques to the problem of marginal release. Here, a database refers to a collection of the data of $$n$$n individuals, each characterized by $$d$$d binary attributes. A $$k$$k-way marginal query is specified by a subset $$S$$S of $$k$$k attributes, together with a $$|S|$$|S|-dimensional binary vector $$\beta $$β specifying their values. The true answer to this query is a count of the number of people in the database whose attribute vector restricted to $$S$$S agrees with $$\beta $$β. Information theoretically, the error complexity of marginal queries--how "wrong" do the answers have to be in order to preserve differential privacy--is well understood: the per-query additive error is known to be at least $$\varOmega (\min \{ \sqrt{n},d^{k/2}\})$$Ω(min{n,dk/2}) and at most $$\tilde{O}(\sqrt{n}d^{{\lceil k/2\rceil /4}})$$O~(nd?k/2?/4). However, no polynomial time algorithm with error complexity as low as the information-theoretic upper bound is known for small $$n$$n. We present a polynomial time algorithm that matches the best known information-theoretic bounds when $$k=2$$k=2; more generally, by reducing to the case $$k=2$$k=2, for any distribution on marginal queries, our algorithm achieves average error at most $$\tilde{O}(\sqrt{n}d^{{\lceil k/2\rceil /4}})$$O~(nd?k/2?/4), an improvement over previous work when $$k$$k is small and when error $$o(n)$$o(n) is desirable. Using private boosting, we are also able to give nearly matching worst-case error bounds. Our algorithms are based on the geometric techniques of Nikolov et al. (Proceedings of the 45th Annual ACM Symposium on Theory of Computing, STOC'13, pp 351---360. ACM Press, New York, 2013), wherein a vector of "sufficiently noisy" answers is projected onto a particular convex body. We reduce the projection step, which is expensive, to a simple geometric question: given (a succinct representation of) a convex body $$K$$K, find a containing convex body $$L$$L that one can efficiently optimize over, while keeping the Gaussian width of $$L$$L small. This reduction is achieved by a careful use of the Frank---Wolfe algorithm.
Asymmetric Total Synthesis of the Gastroprotective Microbial Agent AI-77-B.

An enantioselective total synthesis of the pseudopeptide microbial agent AI-77-B, which has shown potent antiulcerogenic properties, is described. The synthesis is convergent and involves the assembly of a dihydroisocoumarin fragment and a hydroxy amino acid. The dihydroisocoumarin derivative was synthesised by means of a Diels-Alder reaction between 1-methoxy-1,3-cyclohexadiene and an alkynyl ester derivative as the dienophile. The alkynyl ester was obtained stereo-selectively by two different synthetic routes: (1) A stereoselective allylation of leucinal, and (2) a titanium enolate-mediated anti-aldol reaction with trichlorobutyraldehyde, a novel homopropargylaldehyde equivalent. The stereocentres of the hydroxy amino acid moiety were generated through a titanium enolate-mediated syn-aldol reaction, Curtius rearrangement, and application of Dondoni's aldehyde homo-logation. Condensation of the dihydroisocoumarin and hydroxy amino acid moieties and subsequent removal of the protecting groups furnished optically active AI-77-B.
DOUBLE MODE CEPHEIDS IN M31

Until now, double mode Cepheids (or beat Cepheids) were known only in the Galaxy, the Magellanic Clouds, and M33. Curiously, none of the more than 2000 Cepheids in M31 was claimed to show two pulsation modes. We conducted a systematic search for double mode Cepheids in the archival data of M31 and discovered four such objects. We identify one of the stars as a first and second overtone pulsator even though its secondary period is subject to strong aliasing. Two stars pulsate in the fundamental mode and the first overtone. Their fundamental periods are 9.392 days and 9.163 days. This makes them the first candidates for fundamental mode and first overtone Cepheids, of which double mode pulsations are caused by the 2:1 resonance of the fundamental mode and the second overtone.
Comparison of Experimental and Computational Shock Structure in a Transonic Compressor Rotor

Measurement of passage shock strength in a transonic compressor rotor using a gas fluorescent technique revealed an unexpected variation in shock strength in the radial direction. An axisymmetric idealization would normally predict that the passage shock strength would gradually weaken when moving radially inward until disappearing at the sonic radius. However, the measurements indicated a sharp peak in strength at the nominal sonic radius. Blade boundary layer separation originating at this point accounts for about one half of the total rotor losses. A numerical computation of the three-dimensional inviscid flow, using time-marching techniques, has accurately predicted in general the radial and tangential variations in passage shock strength and in particular the sharp pressure peak at the nominal sonic radius. The overall shock strength was somewhat over-predicted, but this overprediction may be the result of boundary layer separation in the experiment. This paper presents comparisons between the optical density measurements and computational results and in addition a short analytical discussion which demonstrates that the sharp shock strength rise may occur in many transonic compressor rotors.
IT Project Managers' Perceptions and Use of Virtual Team Technologies

This paper presents the results of a case study pertaining to the use of information and communication media to support a range of project management tasks. A variety of electronic communication tools have evolved to support collaborative work and virtual teams. Few of these tools have focused specifically on the needs of project managers. In an effort to learn how practicing IT project managers employ these tools, data were collected at a North American Fortune 500 industrial company via interviews with IT project managers regarding their use and perceptions of electronic media within the context of their work on project teams. In this study, "virtual" describes the extent to which communication is electronic rather than the extent to which team members are. geographically separated. Although the number of respondents was limited, the richness of the data collected leads to the conclusion that successful project managers and teams become skilled at adapting a variety of existing communication technologies to match the project task or process, the receiver, their own role as sender, and the content of the message. Groupware designers and developers need to better understand project management methods and best practices in order to provide better tools for practitioners, particularly as organizations expand globally and increasingly outsource various functions of their IT development and operations.
The New Deal and the origins of the modern American real estate loan contract

Abstract The fully amortized mortgage loan contract is an important instance of financial innovation in the U.S. residential mortgage market. We examine the adoption of this contract from the 1880s to the 1930s by building and loan (B&L) associations, the nation's most important institutional home mortgage lenders at the time. A chain of complementary innovations by B&Ls gradually reduced the costs of adopting amortization, supporting moderate use by the 1920s. During the crisis of the 1930s, the poor performance of the traditional B&L loan contract radically increased the benefit of adoption, as borrowers demanded the new contract. The adoption examined here occurred primarily in the conventional loan market because B&Ls, unlike other lenders, generally avoided the use of the new Federal Housing Administration insurance program. The New Deal may have had more impact through new federal savings and loan charters, which incorporated many of the complementary innovations that supported the new form of lending.
NEW DEVELOPMENTS FOR THE SITE-SPECIFIC ATTACHMENT OF PROTEIN TO SURFACES

Protein immobilization on surfaces is of great importance in numerous applications in biology and biophysics. The key for the success of all these applications relies on the immobilization technique employed to attach the protein to the corresponding surface. Protein immobilization can be based on covalent or noncovalent interaction of the molecule with the surface. Noncovalent interactions include hydrophobic interactions, hydrogen bonding, van der Waals forces, electrostatic forces, or physical adsorption. However, since these interactions are weak, the molecules can get denatured or dislodged, thus causing loss of signal. They also result in random attachment of the protein to the surface. Site–specific covalent attachment of proteins onto surfaces, on the other hand, leads to molecules being arranged in a definite, orderly fashion and uses spacers and linkers to help minimize steric hindrances between the protein and the surface. This work reviews in detail some of the methods most commonly used as well as the latest developments for the site-specific covalent attachment of protein to solid surfaces.
Asymptotic distribution of the cointegrating vector estimator in error correction models with conditional heteroskedasticity

Abstract This paper explores the asymptotic distribution of the cointegrating vector estimator in error correction models with conditionally heteroskedastic errors. Asymptotic properties of the maximum likelihood estimator (MLE) of the cointegrating vector, which estimates the cointegrating vector and the multivariate GARCH process jointly, are provided. The MLE of the cointegrating vector follows mixture normal, and its asymptotic distribution depends on the conditional heteroskedasticity and the kurtosis of standardized innovations. The reduced rank regression (RRR) estimator and the regression-based cointegrating vector estimators do not consider conditional heteroskedasticity, and thus the efficiency gain of the MLE emerges as the magnitude of conditional heteroskedasticity increases. The simulation results indicate that the relative power of the t -statistics based on the MLE improves significantly as the GARCH effect increases.
Oxygen Nonstoichiometry and Defects in Mn‐Doped Gd2Ti2O7+x

The oxygen nonstoichiometry in Mn-doped Gd{sub 2}Ti{sub 2}O{sub 7}, Gd{sub 2}(Ti{sub 0.975}Mn{sub 0.025}){sub 2}O{sub 7+x}, was measured electrochemically, as a function of temperature and oxygen partial pressure, with the aid of an oxygen titration cell. The analysis of the data shows that the defect equilibrium can be described by considering the dominant point defects to be neutral oxygen interstitials, doubly charged oxygen vacancies, and trivalent and quadrivalent Mn ions substituted in the Ti sites. The enthalpies for the formation of neutral oxygen interstitials and trivalent Mn are determined.
Physical Conditions in the Initial Stages of the Expanding Universe

The detailed nature of the general nonstatic homogeneous isotropic cosmological model as derived from general relativity is discussed for early epochs in the case of a medium consisting of elementary particles and radiation which can undergo interconversion. The question of the validity of the description afforded by this model for the very early super-hot state is discussed. The present model with matter-radiation interconversion exhibits behavior different from non-interconverting models, principally because of the successive freezing-in or annihilation of various constituent particles as the temperature in the expanding universe decreased with time. The numerical results are unique in that they involve no disposable parameters which would affect the time dependence of pressure, temperature, and density.The study of the elementary particle reactions leads to the time dependence of the proton-neutron concentration ratio, a quantity required in problems of nucleogenesis. This ratio is found to lie in the range \ensuremath{\sim}4.5:1-\ensuremath{\sim}6.0:1 at the onset of nucleogenesis. These results differ from those of Hayashi mainly as a consequence of the use of a cosmological model with matter-radiation interconversion and of relativistic quantum statistics, as well as a different value of the neutron half-life.
Nonperturbative renormalization for domain wall fermions and the chiral condensate

Abstract We study the chiral condensate, 〈 ψ ψ〉, and various quark bilinear vertex functions for domain wall fermions at different lattice scales, with both the Wilson and DBW2 gauge actions, in both quenched and dynamical fermion simulations. We use the vertex functions to calculate renormalization factors within a non-perturbative scheme.
Anomalously Weak Cooper Pair-breaking by Exchange Energy in Ferromagnet/Superconductor Bilayers

We report the superconducting transition temperature T c versus thickness d F of Ferromagnet/Superconductor (F/S) bilayers, where F is a strong 3d ferromagnet (Ni, Ni 0.81 Fe 0.19 (Permalloy), Co 0.5Fe 0.5) and S = Nb, taken from superfluid density measurements rather than resistivity. By regrouping the many physical parameters that appear in theory, we show that the effective exchange energy is determined from the F film thickness d F where T c versus d F begins to flatten out. Using this rearranged theory, we conclude 1) the effective exchange energy, E e x , is about 15 times smaller than measured by ARPES and five times smaller than deduced in previous studies similar to ours; 2) the dirty-limit coherence length, ξ F , for Cooper pairs in F is larger than the electron mean free path, l F ; and 3) the 3d-F/Nb interface is enough of a barrier that Cooper pairs typically must hit it several times before getting through. The Py/Nb and CoFe/Nb interfaces are more transparent than the Ni/Nb interface.
A Graph Theoretic Expansion Formula for Cluster Algebras of Classical Type

In this paper we give a graph theoretic combinatorial interpretation for the cluster variables that arise in most cluster algebras of finite type with bipartite seed. In particular, we provide a family of graphs such that a weighted enumeration of their perfect matchings encodes the numerator of the associated Laurent polynomial while decompositions of the graphs correspond to the denominator. This complements recent work by Schiffler and Carroll-Price for a cluster expansion formula for the A n case while providing a novel interpretation for the B n , C n , and D n cases.
Orbifold Hodge numbers of the wreath product orbifolds

Abstract We prove that the wreath product orbifolds studied earlier by the first author provide a large class of higher dimensional examples of orbifolds whose orbifold Hodge numbers coincide with the ordinary ones of suitable resolutions of singularities. We also make explicit conjectures on elliptic genera for the wreath product orbifolds.
Ketone synthesis under neutral conditions. Cu(I) diphenylphosphinate-mediated, palladium-catalyzed coupling of thiol esters and organostannanes.

A versatile approach to ketone synthesis is described. The reaction relies on the palladium-catalyzed, copper diphenylphosphinate-mediated coupling of thiol esters with organostannanes under neutral reaction conditions. This reaction complements the previously described coupling of thiol esters with boronic acids that used dual thiophilic−borophilic activation methodology.
The Origin of Carbon Monoxide in Neptune's Atmosphere

The CO abundance in the observable atmosphere of Neptune can be plausibly explained by rapid vertical mixing from the deeper atmosphere if Neptune has a greater complement of water than Uranus. Thermochemical equilibrium and kinetic calculations reveal that Neptune must and Uranus may have about 10 times more oxygen than carbon, whereas for Jupiter and Saturn equal enrichments of carbon and oxygen are satifactory to explain the observed CO abundances by deep vertical mixing. Relative to hydrogen and solar composition, the respective enrichment factors for carbon and oxygen are 41, 440 (Neptune); 32, less than or equal 260 (Uranus); 6.6, 6.6 (Saturn); and 2.8, 2.8 (Jupiter). Because water ice is the most refractory ice among the ices assumed to be present in the outer solar nebula, the most massive H2O enrichment is expected for the outermost planet of this group. Thus, Neptune can indeed be regarded as the 'god of the seas.'
MITIGATING THE TYRANNY OF PUBLIC OPINION: Anonymous Discourse and the Ethic of Sincerity*

Public opinion breeds tyranny by forcing individuals to refrain from voicing their genuine thoughts and feelings. The means used to mitigate such tyranny include the separation of governmental powers, the ethic of tolerance, and the secret ballot. Yet neither individually nor collectively do these devices prevent the emergence and persistence of social taboos. This paper proposes two additional corrective devices. One is an electronic instrument that would enable public officials to deliberate on socially sensitive matters behind a veil of anonymity. The other is an ethic that would enhance the utility citizens derive from truthfulness on political matters.
Using Investment Consumption Value to Select Asset Classes: A Non-Traditional Approach

The asset allocation decision is arguably the most important decision in the investment process. It involves allocating an investor9s portfolio among a set of desirable asset classes, but the investor must first define the asset classes to consider. The concept of investment-consumption value may help investors decide on including non-traditional asset classes such as hedge funds or commodities. The decision framework is grounded in the financial economics of the consumption CAPM and state/preference models. From this perspective, commodities are one example to consider as an investable asset class.
The Spectra of heterotic standard model vacua

A formalism for determining the massless spectrum of a class of realistic heterotic string vacua is presented. These vacua, which consist of SU(5) holomorphic bundles on torus-fibered Calabi-Yau threefolds with fundamental group Z_2, lead to low energy theories with standard model gauge group (SU(3)_C x SU(2)_L x U(1)_Y)/Z_6 and three families of quarks and leptons. A methodology for determining the sheaf cohomology of these bundles and the representation of Z_2 on each cohomology group is given. Combining these results with the action of a Z_2 Wilson line, we compute, tabulate and discuss the massless spectrum.
Catalytic Hydrogenation of Diketones

Abstract Our success with a preparation of 3,3-dimethlcyclohexanone from 5,5-dimethyl-1,3-cyclohexanedione1 encouraged us to investigate the generality and utility of this rection. Using a scaled-down version of our earlier procedure,1,2 we examined the products obtained from catalytic hydrogenation of several representative diketones, as shown below.
Hall viscosity from gauge/gravity duality

In (2+1)-dimensional systems with broken parity, there exists yet another transport coefficient, appearing at the same order as the shear viscosity in the hydrody- namic derivative expansion. In condensed matter physics, it is referred to as "Hall viscos- ity". We consider a simple holographic realization of a (2+1)-dimensional isotropic fluid with broken spatial parity. Using techniques of fluid/gravity correspondence, we uncover that the holographic fluid possesses a nonzero Hall viscosity, whose value only depends on the near-horizon region of the background. We also write down a Kubo's formula for the Hall viscosity. We confirm our results by directly computing the Hall viscosity using the formula.
Determining the number of principal components for best reconstruction

Abstract A well-defined variance of reconstruction error (VRE) is proposed to determine the number of principal components in a PCA model for best reconstruction. Unlike most other methods in the literature, this proposed VRE method has a guaranteed minimum over the number of PC's corresponding to the best reconstruction. Therefore, it avoids the arbitrariness of other methods with monotonic indices. The VRE can also be used to remove variables that are little correlated with others and cannot be reliably reconstructed from the correlation-based PCA model. The effectiveness of this method is demonstrated with a simulated process.
On the nature of the ion pair as a nucleophile in Pd catalyzed alkylations with dienyl carboxylates

Abstract The regioselectivity of nucleophilic attack on unsymmetrical dienyl acetates depends upon the nature of the nucleophile in which the use of the tetrahexylammonium salt decreases the rate of nucleophilic attack. Equilibration of the products does not occur to any significant extent under the conditions reported here.