cssi/SciSciGPT-SciSciNet huggingface dataset:
Regularized Laplacian Estimation and Fast Eigenvector Approximation

Recently, Mahoney and Orecchia demonstrated that popular diffusion-based procedures to compute a quick approximation to the first nontrivial eigenvector of a data graph Laplacian exactly solve certain regularized Semi-Definite Programs (SDPs). In this paper, we extend that result by providing a statistical interpretation of their approximation procedure. Our interpretation will be analogous to the manner in which l2-regularized or l1-regularized l2-regression (often called Ridge regression and Lasso regression, respectively) can be interpreted in terms of a Gaussian prior or a Laplace prior, respectively, on the coefficient vector of the regression problem. Our framework will imply that the solutions to the Mahoney-Orecchia regularized SDP can be interpreted as regularized estimates of the pseudoinverse of the graph Laplacian. Conversely, it will imply that the solution to this regularized estimation problem can be computed very quickly by running, e.g., the fast diffusion-based PageRank procedure for computing an approximation to the first nontrivial eigenvector of the graph Laplacian. Empirical results are also provided to illustrate the manner in which approximate eigenvector computation implicitly performs statistical regularization, relative to running the corresponding exact algorithm.
The motivic adams spectral sequence

We present some data on the cohomology of the motivic Steenrod algebra over an algebraically closed field of characteristic 0. Our results are based on computer calculations and a motivic version of the May spectral sequence. We discuss features of the associated Adams spectral sequence and use these tools to give new proofs of some results in classical algebraic topology. We also consider a motivic Adams‐ Novikov spectral sequence. The investigations reveal the existence of some stable motivic homotopy classes that have no classical analogue. 55T15, 14F42
High-temperature Mars-to-Earth transfer of meteorite ALH84001

Martian meteorites provide crucial insights into Martian evolution and interplanetary mass transfer, including the potential for exogenesis. ALH84001 is the oldest Martian meteorite discovered so far, and has been used to derive important conclusions about Martian surface temperatures and very low-temperature Mars-to-Earth transfer. To better constrain the thermal evolution and shock metamorphic history of ALH84001, we applied (U–Th)/He thermochronometry to single grains of phosphate (merrillite) from ALH84001. The (U–Th)/He ages of individual phosphate grains in ALH84001 range from 60 Ma to 1.8 Ga, with a weighted mean of ~830 Ma. This broad age distribution reflects multiple diffusion domains, and requires a relatively high-temperature resetting event younger than ∼ 60 Ma. These new data are combined with the published whole-rock (maskelynite as a main Ar reservoir) 40 Ar/ 39 Ar age spectra which show 5–8% fractional loss of radiogenic 40 Ar since 4.0 Ga. He diffusion in both terrestrial and extraterrestrial apatite has a significantly higher activation energy (138 ∼184 kJ/mol) than Ar diffusion in maskelynite (75 kJ/mol), leading to an important “kinetic crossover” in fractional loss contours for these systems. Taken together, the phosphate (U–Th)/He and whole-rock 40 Ar/ 39 Ar ages require both very low surface temperatures on Mars, and one or more short-lived, high-temperature, shock events after 4.0 Ga. We suggest that the last shock event occurred with ejection of ALH84001 from Mars, and reached a peak temperature of approximately 400 °C. These results undermine the proposed low-temperature ejection hypothesis for ALH84001, but support long-lived extremely cold Martian surface temperatures. © 2007 Elsevier B.V. All rights reserved.
Automorphism groups of a graph and a vertex-deleted subgraph

Understanding the structure of a graph along with the structure of its subgraphs is important for several problems in graph theory. Two examples are the Reconstruction Conjecture and isomorph-free generation. This paper raises the question of which pairs of groups can be represented as the automorphism groups of a graph and a vertex-deleted subgraph. This, and more surprisingly the analogous question for edge-deleted subgraphs, are answered in the most positive sense using concrete constructions.
Modeling of Nonlinear Guided Waves and Applications to Structural Health Monitoring

AbstractPropagation of nonlinear waves in solid waveguides is a branch of wave mechanics that has received ever-increasing interest in the last few decades. Nonlinear guided waves are promising candidates for interrogating long waveguide-like structures as they conveniently combine high sensitivity to peculiar structural conditions (defects, quasi-static loads, instability conditions), typical of nonlinear parameters, with large inspection ranges, characteristic of wave propagation in confined media. However, the mathematical framework governing the nonlinear guided wave phenomena becomes extremely difficult when characterized to waveguides that are complex in either material (damping, anisotropy, heterogeneous, and the like) or geometry (multilayers, geometric periodicity, and the like). Therefore, the successful use of nonlinear guided waves as a structural diagnostic tool is not always a trivial task. In particular, the efficiency of nonlinear structural health monitoring (SHM) techniques based on high...
Extragalactic cosmic rays.

In these lectures I shall largely be concerned with the view that the bulk of the primary cosmic rays is of extragalactic origin. In order to set the stage for these ideas, a survey of the components of the extragalactic universe will be given. Then much of the discussion will centre about the various types of extragalactic non-thermal sources.
Value Creation and Knowledge Loss: The Case of Cremonese Stringed Instruments

To understand how the value of cultural products is determined, one must consider how evaluations evolve over time and have an impact on the conditions supporting knowledge development. If evaluations do not fully recognize the potential value of a cultural product, the associated knowledge—especially tacit knowledge—may be lost rather than passed on, thus jeopardizing subsequent attempts to reproduce the valued product. We examine these dynamics by studying how value was attributed to Cremonese stringed instruments. The value the Cremonese masters created was first recognized in the 16th century, and in the early 18th century, new methods to strengthen instrument sound and sonority were developed. However, the value of these new developments was not widely recognized until the 19th century, when, in evaluating musical performance, performers, critics, and public audiences took over from royal courts, and they selected Cremonese instruments as the best for performing the emerging Romantic music. We consider how the dynamics of value determination over time have implications for knowledge management processes.
Statistical distributions of earthquake numbers: consequence of branching process

We discuss various statistical distributions of earthquake numbers. Previously we derived several discrete distributions to describe earthquake numbers for the branching model of earthquake occurrence: these distributions are the Poisson, geometric, logarithmic, and the negative binomial (NBD). The theoretical model is the `birth and immigration' population process. The first three distributions above can be considered special cases of the NBD. In particular, a point branching process along the magnitude (or log seismic moment) axis with independent events (immigrants) explains the magnitude/moment-frequency relation and the NBD of earthquake counts in large time/space windows, as well as the dependence of the NBD parameters on the magnitude threshold (magnitude of an earthquake catalogue completeness). We discuss applying these distributions, especially the NBD, to approximate event numbers in earthquake catalogues. There are many different representations of the NBD. Most can be traced either to the Pascal distribution or to the mixture of the Poisson distribution with the gamma law. We discuss advantages and drawbacks of both representations for statistical analysis of earthquake catalogues. We also consider applying the NBD to earthquake forecasts and describe the limits of the application for the given equations. In contrast to the one-parameter Poisson distribution so widely used to describe earthquake occurrence, the NBD has two parameters. The second parameter can be used to characterize clustering or over-dispersion of a process. We determine the parameter values and their uncertainties for several local and global catalogues, and their subdivisions in various time intervals, magnitude thresholds, spatial windows, and tectonic categories. The theoretical model of how the clustering parameter depends on the corner (maximum) magnitude can be used to predict future earthquake number distribution in regions where very large earthquakes have not yet occurred.
Characterization and Constitutive Modeling of Composite Materials Under Static and Dynamic Loading

Composite materials were characterized under quasi-static and dynamic loading and a constitutive model was adapted to describe the nonlinear multi-axial behavior of the materials under varying strain rate. The materials investigated were unidirectional glass fiber/vinylester, and carbon fiber/epoxy composites. Multiaxial static and dynamic experiments were conducted using off-axis specimens to produce stress states combining transverse normal and in-plane shear stresses. Stress-strain curves were obtained for various loading orientations with respect to the fiber direction at three strain rates, quasi-static, intermediate and high strain rate. A nonlinear constitutive model is proposed to describe the rate-dependent behavior under states of stress including tensile and compressive loading. Experimental results were in good agreement with predictions of the proposed constitutive model.
Synthesis and Properties of Cyclopropane-Derived Peptidomimetics

Small peptides exhibit a wide range of biological activities, but although there are some notable exceptions, they are not generally useful as drugs. This has spurred widespread interest in designing peptidomimetics and introducing them as replacements of portions of native peptides to enhance their biological properties. Special attention has been focused upon rigid replacements because of their potential to preorganize the resulting pseudopeptide in a conformation corresponding to its bound structure. Toward this goal, we invented trisubstituted cyclopropanes as novel peptidomimetics, anticipating that the cyclopropane ring would locally orient the backbone and the corresponding amino acid side chain in the biologically active conformation. Selected aspects of the syntheses and applications of these cyclopropane-derived peptidomimetics are presented in this Account.
Charge Migration in Dicationic Electrophiles and Its Application to the Synthesis of Aza-polycyclic Aromatic Compounds

[reaction: see text] Superacid-promoted reactions of dicationic electrophiles have been studied, and the positive charge centers are found to migrate apart in a predictable manner. Using isotopic labeling the charge migration is found in one system to occur through successive deprotonation-reprotonation steps. The charge migration chemistry is the basis for new general synthetic route to aza-polycyclic aromatic compounds.
Gamma-rays produced in cosmic-ray interactions and the TeV-band spectrum of RX J1713.7-3946

In this work we study the individual contribution to diffuse c-ray emission from the secondary products in hadronic interactions generated by cosmic rays (CRs), in addition to the contribution of p 0 decay via the decay mode p 0 ! 2c. For that purpose we employ the Monte Carlo particle collision code DPMJET3.04 to determine the multiplicity spectra of various secondary particles with c’s as the final decay state, that result from inelastic collisions between cosmic-ray protons and helium nuclei and the interstellar medium with standard composition. By combining the simulation results with a parametric model of c-ray production by cosmic rays with energies below a few GeV, where DPMJET appears unreliable, we thus derive an easy-to-use c-ray production matrix for cosmic rays with energies up to about 10 PeV. We apply the c-ray production matrix to the GeV excess in diffuse galactic c-rays observed by EGRET. Although the non-p 0 decay components have contributed to the total emission with a different spectrum from the p 0 -decay component, they are insufficient to
Worst-case identification of nonlinear fading memory systems

Abstract In this paper, the problem of asymptotic identification for fading memory systems in the presence of bounded noise is studied. For any experiment, the worst-case error is characterized in terms of the diameter of the worst-case uncertainty set. Optimal inputs that minimize the radius of uncertainty are studied and characterized. Finally, a convergent algorithm that does not require knowledge of the noise upper bound is furnished. The algorithm is based on interpolating data with spline functions, which are shown to be well suited for identification in the presence of bounded noise—more so than other basis functions such as polynomials.
Food marketing liberalization and trader entry: Evidence from Madagascar

Abstract Food marketing liberalization was expected to induce massive trader entry and competitive markets in Africa. Despite evidence of trader entry, enterprise expansion remains difficult and many claim market power persists, though perhaps in different hands. This paper confronts this puzzle of substantial market entry that might not foster competition. Data from Madagascar reveal distinct groups within rural food marketing channels, separated by intraindustry mobility barriers that limit entry to a few niches. Moreover, individuals' place within the rural marketing network is defined largely by a priori social identity, so the experience of food marketing liberalization varies across socially distinct subpopulations.
Are Crises Good for Long-term Growth? The Role of Political Institutions

Abstract This paper provides empirical evidence for the importance of institutions in determining the outcome of crises on long-term growth. We show that once unobserved country-specific effects and other sources of endogeneity are accounted for, political institutions affect growth through their interaction with crises. In particular, we find that the effect of a crisis on long-run growth is conditioned by the prevailing institutional environment. In countries with democratic institutions, the negative effect of crises is mitigated, while in countries with autocratic institutions, the negative effect is exacerbated.
UNUSUALLY WIDE BINARIES: ARE THEY WIDE OR UNUSUAL?

We describe an astrometric and spectroscopic campaign to confirm the youth and association of a complete sample of candidate wide companions in Taurus and Upper Sco. Our survey found 15 new binary systems (three in Taurus and 12 in Upper Sco) with separations of 3''-30'' (500-5000 AU) among all of the known members with masses of 2.5-0.012 M {sub sun}. The total sample of 49 wide systems in these two regions conforms to only some expectations from field multiplicity surveys. Higher mass stars have a higher frequency of wide binary companions, and there is a marked paucity of wide binary systems near the substellar regime. However, the separation distribution appears to be log-flat, rather than declining as in the field, and the mass ratio distribution is more biased toward similar-mass companions than the initial mass function or the field G-dwarf distribution. The maximum separation also shows no evidence of a limit at approx<5000 AU until the abrupt cessation of any wide binary formation at system masses of approx0.3 M {sub sun}. We attribute this result to the post-natal dynamical sculpting that occurs for most field systems; our binary systems will escape to the field intact, but most field stars aremore » formed in denser clusters and undergo significant dynamical evolution. In summary, only wide binary systems with total masses approx<0.3 M {sub sun} appear to be 'unusually wide'.« less
Potential therapy for mucus hypersecretion in chronic obstructive pulmonary disease

Mucus hypersecretion is a major pathophysiologic feature of chronic bronchitis. Although mucus functions as a barrier and a facilitator of mucociliary clearance, persistent mucus hypersecretion results in airway obstruction and compromised clearance of inhaled bacteria and particles from the airways of patients with chronic obstructive pulmonary disease. Treatment of mucus hypersecretion is a major therapeutic target; however, mechanisms of mucus hypersecretion remain unknown. Herein, we present evidence that human neutrophil elastase (HNE), a pathophysiologically relevant stimulant of mucus hypersecretion in the airways of patients with chronic bronchitis, provokes release of mucin (the glycoprotein component of mucus) by human airway epithelial cells in vitro. Signaling molecules involved in HNE-induced mucin hypersecretion include protein kinase C, specifically the delta isoform, and the myristoylated alanine-rich C kinase substrate protein. These molecules represent potential therapeutic targets for r...
RbjMk[Fe(CN)6]l (M = Co, Ni) Prussian Blue Analogue Hollow Nanocubes: a New Example of a Multilevel Pore System

A facile surfactant-free route to synthesize uniform Rb0.4M4[Fe(CN)6]2.8·7.2H2O (M = Co, Ni) hollow nanoparticles is described. Rb1.6Mn4[Fe(CN)6]3.2·4.8H2O serves as a sacrificial/removable core in the synthesis of core@shell heterostructures. After dissolution of the cores under very mild conditions, the crystalline hollow nanocubes feature well-defined micro-, meso-, and macropores. The surfactant-free approach preserves the reactivity of the Prussian blue analogue surface as evidenced by the subsequent synthesis of hollow shell@shell heterostructures.
Global microRNA expression is essential for murine mast cell development in vivo.

MicroRNAs (miRNAs) are small, noncoding RNAs that have been shown to play a critical role in normal physiology and disease, such as hematopoietic development and cancer. However, their role in mast-cell function and development is poorly understood. The major objective of this study was to determine how global miRNA expression affects mast-cell physiology. The RNase III endonuclease, Dicer, is required for the processing of pre-miRNAs into mature miRNAs. To investigate the effect of global miRNA depletion on mast cells in vivo, we generated a mast-cell-specific knock out of Dicer in mice. Transgenic mice (Mcpt5-Cre) that express Cre selectively in connective tissue mast cells were crossed with mice carrying the floxed conditional Dicer allele (Dicer fl/fl). Mcpt5-Cre × Dicer fl/fl mice with homozygous Dicer gene deletion in mast cells were found to have a profound mast-cell deficiency with near complete loss of peritoneal, gastrointestinal, and skin mast cells. We examined the in vivo functional consequence of mast-cell-specific Dicer deletion using an immunoglobulin-E-dependent passive systemic anaphylaxis murine model. Immunoglobulin-E-sensitized wild type Mcpt5-Cre × Dicer +/+ and heterozygous Mcpt5-Cre × Dicer fl/+ mice show marked hypothermia with antigen; however, homozygous Mcpt5-Cre × Dicer fl/fl mice were completely unresponsive to antigen challenge. These studies suggest a critical role for Dicer and miRNA expression for establishment of tissue compartments of functional mast cells in vivo.
Tandem Development of Aqueous Indium Chemistry and Ring‐Closing Metathesis as a General Route to Fused‐Ring α‐Methylene‐γ‐butyrolactones

A program directed toward a general synthesis of α-methylenelactones cis- or trans-fused to larger rings is reported. The protocol originates with two ω-unsaturated aldehydes of the same or different chain length. One of these is initially transformed by way of the Baylis–Hillman reaction into a functionalized allylic bromide. Merger of the two building blocks is subsequently accomplished in aqueous solution with powdered indium metal serving as the initiator. Once the lactone ring is crafted, the end products are generated by application of ring-closing metathesis. The central issues surrounding this final step are the effects of the stereochemical disposition of the side chains, the consequences of ring strain, and the locus of the double bonds on cyclization efficiency.
Finding the Median (Obliviously) with Bounded Space

We prove that any oblivious algorithm using space \(S\) to find the median of a list of \(n\) integers from \(\{1,\ldots ,2n\}\) requires time \(\varOmega (n\log \log _S n)\). This bound also applies to the problem of determining whether the median is odd or even. It is nearly optimal since Chan, following Munro and Raman, has shown that there is a (randomized) selection algorithm using only \(s\) registers, each of which can store an input value or \(O(\log n)\)-bit counter, that makes only \(O(\log \log _s n)\) passes over the input. The bound also implies a size lower bound for read-once branching programs computing the low order bit of the median and implies the analog of \(\mathsf P\ne \mathsf {NP}\cap \mathsf c\mathsf o\mathsf N\mathsf P\) for length \(o(n\log \log n)\) oblivious branching programs.
Theory of unidirectional photorefractive ring oscillators

Amplification owing to holographic two-wave mixing in photorefractive crystals can be utilized to achieve unidirectional ring oscillation. Unlike for the conventional gain medium (e.g., He–Ne), the gain bandwidth of photorefractive two-wave coupling is very narrow (a few hertz for BaTiO3). Despite this fact, the ring resonator can still oscillate over a large range of cavity detuning. A theory is presented that describes how the oscillating mode attains the round-trip phase condition.
New Quaternary Selenoantimonates AHgSbSe3 (A = Rb, Cs): Synthesis, Structures and Optical Properties

Solvothermal reactions in ethylenediamine have resulted in two quaternary mercury containing selenoantimonates: RbHgSbSe3 (I) and CsHgSbSe3 (II). Compound I crystallizes in monoclinic system, space group P2l/c (no. 14) with a = 7.758(2)A, b = 11.234(2)A, c = 8.849(2) A, β = 106.60(3)°, V = 739.1(3)A3, Z = 4. Compound II crystallizes in orthorhombic system, space group Cmcm (no. 63) with a = 4.444(1)A, b = 15.514(6)A, c = 11.261(7) A, V = 776.4(6) A3, Z = 4. Both compounds are layered materials and their crystal structures are closely related. Both contain layers of ∞2[HgSbSe3-] separated by alkali-metal cations A+ (Rb, Cs). Diffuse reflectance experiments show that both compounds are semiconductors with estimated band gaps of 1.7 eV for I and 1.6 eV for II, respectively.
Functional recovery following traumatic spinal cord injury mediated by a unique polymer scaffold seeded with neural stem cells.

To better direct repair following spinal cord injury (SCI), we designed an implant modeled after the intact spinal cord consisting of a multicomponent polymer scaffold seeded with neural stem cells. Implantation of the scaffold–neural stem cells unit into an adult rat hemisection model of SCI promoted long-term improvement in function (persistent for 1 year in some animals) relative to a lesion-control group. At 70 days postinjury, animals implanted with scaffold-plus-cells exhibited coordinated, weight-bearing hindlimb stepping. Histology and immunocytochemical analysis suggested that this recovery might be attributable partly to a reduction in tissue loss from secondary injury processes as well as in diminished glial scarring. Tract tracing demonstrated corticospinal tract fibers passing through the injury epicenter to the caudal cord, a phenomenon not present in untreated groups. Together with evidence of enhanced local GAP-43 expression not seen in controls, these findings suggest a possible regeneration component. These results may suggest a new approach to SCI and, more broadly, may serve as a prototype for multidisciplinary strategies against complex neurological problems.
Changing fertility rates in developed countries. The impact of labor market institutions

During the last two decades fertility rates have decreased and have become positively correlated with female participation rates across OECD countries. I use a panel of 23 OECD nations to study how different labor market arrangements shaped these trends. High unemployment and unstable contracts, common in Southern Europe, depress fertility, particularly of younger women. To increase lifetime income though early skill-acquisition and minimize unemployment risk, young women postpone (or abandon) childbearing. Further, both a large share of public employment, by providing employment stability, and generous maternity benefits linked to previous employment, such as those in Scandinavia, boost fertility of the 25–29 and 30–34 year old women.
Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe.

Abstract We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B1S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B1S field is 13 μT/W1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is γSB1S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ϵ) vs. ω1S/(2π) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment.
Phase Separation of Lipid Membranes Analyzed with High-Resolution Secondary Ion Mass Spectrometry

Lateral variations in membrane composition are postulated to play a central role in many cellular events, but it has been difficult to probe membrane composition and organization on length scales of tens to hundreds of nanometers. We present a high-resolution imaging secondary ion mass spectrometry technique to reveal the lipid distribution within a phase-separated membrane with a lateral resolution of approximately 100 nanometers. Quantitative information about the chemical composition within small lipid domains was obtained with the use of isotopic labels to identify each molecular species. Composition variations were detected within some domains.
Webly Supervised Learning of Convolutional Networks

We present an approach to utilize large amounts of web data for learning CNNs. Specifically inspired by curriculum learning, we present a two-step approach for CNN training. First, we use easy images to train an initial visual representation. We then use this initial CNN and adapt it to harder, more realistic images by leveraging the structure of data and categories. We demonstrate that our two-stage CNN outperforms a fine-tuned CNN trained on ImageNet on Pascal VOC 2012. We also demonstrate the strength of webly supervised learning by localizing objects in web images and training a R-CNN style [19] detector. It achieves the best performance on VOC 2007 where no VOC training data is used. Finally, we show our approach is quite robust to noise and performs comparably even when we use image search results from March 2013 (pre-CNN image search era).
Speed of Issuance, Lender, Specialization, and the Rise of the 144A Debt Market

Using a large sample of convertible and straight debt issues in the public, 144A, and bank loan markets from 1991 to 2004, we find that the 144A market has risen largely at the expense of the nonshelf public market, the overwhelming majority of the 144A issues are subsequently registered, and straight debt issuers with the highest credit quality and transparency tend to use the shelf public market. Our findings suggest that firms’ preference for speed of issuance drives the growth of the 144A market, and banks and qualified institutional buyers have advantages over public lenders in handling credit risk and information asymmetry.
A class of low-density parity-check codes constructed based on Reed-Solomon codes with two information symbols

This letter presents an algebraic method for constructing regular low-density parity-check (LDPC) codes based on Reed-Solomon codes with two information symbols. The construction method results in a class of LDPC codes in Gallager's original form. Codes in this class are free of cycles of length 4 in their Tanner graphs and have good minimum distances. They perform well with iterative decoding.
Mixing time of exponential random graphs.

A variety of random graph models has been developed in recent years to study a range of problems on networks, driven by the wide availability of data from many social, telecommunication, biochemical and other networks. A key model, extensively used in sociology literature, is the exponential random graph model. This model seeks to incorporate in random graphs the notion of reciprocity, that is, the larger than expected number of triangles and other small subgraphs. Sampling from these distributions is crucial for parameter estimation hypothesis testing and more generally for understanding basic features of the network model itself. In practice, sampling is typically carried out using Markov chain Monte Carlo, in particular, either the Glauber dynamics or the Metropolis–Hastings procedure. In this paper we characterize the high and low temperature regimes of the exponential random graph model. We establish that in the high temperature regime the mixing time of the Glauber dynamics is Θ(n2 log n), where n is the number of vertices in the graph; in contrast, we show that in the low temperature regime the mixing is exponentially slow for any local Markov chain. Our results, moreover, give a rigorous basis for criticisms made of such models. In the high temperature regime, where sampling with Markov chain Monte Carlo is possible, we show that any finite collection of edges is asymptotically independent; thus, the model does not possess the desired reciprocity property and is not appreciably different from the Erdős–Renyi random graph.
The Multiplicative Inverse Eigenvalue Problem over an Algebraically Closed Field

Let M be an n × n square matrix and let $p(\lambda)$ be a monic polynomial of degree n. Let $\mathcal{Z}$ be a set of n × n matrices. The multiplicative inverse eigenvalue problem asks for the construction of a matrix $Z\in\mathcal{Z}$ such that the product matrix MZ has characteristic polynomial $p(\lambda)$. In this paper we provide new necessary and sufficient conditions when $\mathcal{Z}$ is an affine variety over an algebraically closed field.
Rich chemistry of nitroso compounds

Nitrosobenzene or nitrosopyridine are found to be attractive electrophiles in catalytic enantioselective carbon–nitrogen and/or carbon–oxygen bond forming reactions. In the presence of designer Lewis or Bronsted acid catalysts, catalytic enantioselective O- and N-nitroso aldol reaction or nitroso Diels–Alder reaction proceed smoothly. The scope and limitation of new catalytic processes are described.
A comment on Doreian's regular equivalence in symmetric structures

I read with interest Pat Doreian’s recent article (1987) on the problem of running REGE (White 1984) on symmetric matrices. As many people have discovered to their chagrin, the problem is that in a symmetric matrix, REGE finds that all actors except isolates are equivalent to all others no matter what the data. This is troubling in cases where clear differences in structural position appear to exist between some actors. Whereas for directed graphs the results of REGE correspond closely with intuitive notions of role (Nadel 1957; Sailer 1978; Faust 1985), for symmetric data this correspondence seems to break down. Doreian’s solution, which I call the “Doreian Split”, is creative and practical, and yields intuitively satisfying results. If there really is a problem, that is. Doreian illustrates the situation with the graph shown in Figure 1. Most people immediately spot four groups of equivalent actors: (a), (b, c), (d, - - g), and (h * - 0). Actors within each group are similarly related to members of other groups, a condition consistent with many intuitive notions of role, and with the notion of regular equivalence (White and Reitz 1983) in particular. Doreian explains it this way:
Health and the Economy in the United States from 1750 to the Present

I discuss the health transition in the United States, bringing new data to bear on health indicators, and investigating the changing relationship between health, income, and the environment. I argue that scientific advances played an outsize role and that health improvements were largest among the poor. Health improvements were not a precondition for modern economic growth. The gains to health are largest when the economy has moved from "brawn" to "brains" because this is when the wage returns to education are high, leading the healthy to obtain more education. More education may improve use of health knowledge, producing a virtuous cycle.
Durable-Goods Monopoly with Varying Demand

This paper solves for the proflt maximising strategy of a durable{goods monopolist when incoming demand varies over time. Each period, additional consumers enter the market; these consumers can then choose whether and when to purchase. We flrst characterise the consumer’s utility maximisation problem and, under a monotonicity condition, show the proflt maximising allocation can be solved through a myopic algorithm, which has an intuitive marginal revenue interpretation. Consumers’ ability to delay creates an asymmetry in the optimal price path, which exhibits fast increases and slow declines. This asymmetry pushes the price level above that charged by a flrm facing the average level of demand. Applications of this framework include deterministic demand cycles, one{ofi shocks and IID demand draws. The optimal policy outperforms renting and can be implemented by a time consistent best{price provision.
A working model of stroke recovery from rehabilitation robotics practitioners

We reviewed some of our initial insights about the process of upper-limb behavioral recovery following stroke. Evidence to date indicates that intensity, task specificity, active engagement, and focusing training on motor coordination are key factors enabling efficacious recovery. On modeling, experience with over 400 stroke patients has suggested a working model of recovery similar to implicit motor learning. Ultimately, we plan to apply these insights in the development of customized training paradigms to enhance recovery.
On the detection of cosmological neutrinos by coherent scattering

There have been several proposals that the sea of cosmological relic neutrinos could be detected by the energy, momentum, or angular momentum transferred during their coherent interaction with matter. We show that all but one of these proposals is incorrect and that the one exception leads to an effect that is probably immeasurably small. We first review the existing limits on the cosmological neutrinos and describe the expectations from the standard hot big-bang model. We then prove a general theorem that if the time average of the neutrino flux is spatially homogeneous (which is expected for cosmological neutrinos), then to first order in the weak coupling the energy and momentum transfer to any microscopic or macroscopic target is zero. Similarly, the angular momentum transfer is zero unless the target has a nonzero polarization or current density (but in this case the effect is probably immeasurably small). No assumption is made concerning the isotropy of the neutrino flux. Finally, we reexamine the individual proposals using the language of geometrical optics and show where all but one of them was incorrect. In particular, we prove that the momentum and angular momentum transferred by refraction from a homogeneous incoming beam to a (microscopically) isotropic target vanish to order $n\ensuremath{-}1$, with $n$ the index of refraction.
Tree-structured piecewise linear adaptive equalization

The use of a tree-structured piecewise linear filter as an adaptive equalizer is proposed. In the tree equalizer, each node in a tree is associated with a linear filter restricted to a polygonal domain, and each subtree is associated with a piecewise linear filter. A training sequence is used to adaptively update the filter coefficients and domains at each node, and to select the best subtree and corresponding piecewise linear filter. The tree-structured approach offers several advantages. First, it makes use of standard linear adaptive filtering techniques at each node to find the corresponding conditional linear filter. Second, it allows for efficient selection of the subtree and corresponding piecewise linear filter of appropriate complexity. Overall, the approach is computationally efficient and conceptually simple. Numerical experiments are performed to show the advantages of tree-structured piecewise linear and piecewise decision feedback equalizers over linear, polynomial, and decision feedback equalizers for the equalization of channels with severe intersymbol interference. >
Making distance judgments in real and virtual environments: does order make a difference?

Virtual environments are an exciting new medium for investigating difficult-to-study problems under realistic and controlled conditions (Plumert, Kearney, & Cremer, 2004). One question that arises when using virtual environments to study human behavior is how well does distance perception in real and virtual environments correspond? Recently, Plumert, Kearney, Cremer, and Recker (2005) asked people to estimate how long it would take to walk to targets in real and virtual environments by starting and stopping a stopwatch while imagining walking to a target person standing between 20 and 120 ft. away. The real environment was a large grassy lawn in front of a university building. This scene was replicated in a virtual environment using a nonstereoscopic, large-screen immersive display system. Participants made estimates either in the real or virtual environment first. Time-to-walk estimates did not differ across environments when people made estimates in the real environment first. When people made estimates in the virtual environment first, however, estimates were significantly shorter in the virtual than in the real environment.
Applications of Aziridinium Ions: Selective Syntheses of Pyrazolidin-3-ones and Pyrazolo[1,2-a]pyrazoles

Reaction of ethyl (2S*,3R*)-3-chloro-2-(dialkylamino)-3-phenylpropanoates (4) with hydrazine monohydrate gave pyrazolidin-3-ones (5) via selective opening of the in situ generated aziridinium ions, followed by intramolecular amidation. (1Z,4S*,5S*)-1-Arylmethylidene-4-(dialkylamino)-3-oxo-5-phenylpyrazolidinium-1-ide (6), prepared from pyrazolidin-3-ones (5) and aromatic aldehydes under acid catalysis, reacted with a variety of 1,3-dipolarophiles to afford good yields of pure cycloadducts 7 – 11. The cycloaddition regio- and/or stereoselectivities, in all relevant cases, were also high.
The "Manifesto" of New-Confucianism and the Revival of Virtue Ethics

In 1958, a group of New-Confucians issued “A Manifesto for a Re-Appraisal of Sinology and Reconstruction of Chinese Culture.” Equally in 1958, the British philosopher Elizabeth Anscombe published her classical paper “Modern Moral Philosophy.” These two papers have the same target — modern Western morality — and the solutions they proposed respectively. Yet Anscombe’s paper did not mention Confucianism, and the “Manifesto” ignored Aristotelian tradition of virtue. Furthermore, from 1960s to 1990s, the revival movement of Confucianism and the revival movement of Aristotelian ethics have not had much dialogue. This paper seeks to explain this phenomenon by comparing these two historically important documents. In particular it tries to understand why the “Manifesto” fails to see the similarities between Aristotle and Confucius.
Composition attacks and auxiliary information in data privacy

Privacy is an increasingly important aspect of data publishing. Reasoning about privacy, however, is fraught with pitfalls. One of the most significant is the auxiliary information (also called external knowledge, background knowledge, or side information) that an adversary gleans from other channels such as the web, public records, or domain knowledge. This paper explores how one can reason about privacy in the face of rich, realistic sources of auxiliary information. Specifically, we investigate the effectiveness of current anonymization schemes in preserving privacy when multiple organizations independently release anonymized data about overlapping populations.1. We investigate composition attacks, in which an adversary uses independent anonymized releases to breach privacy. We explain why recently proposed models of limited auxiliary information fail to capture composition attacks. Our experiments demonstrate that even a simple instance of a composition attack can breach privacy in practice, for a large class of currently proposed techniques. The class includes k-anonymity and several recent variants.2. On a more positive note, certain randomization-based notions of privacy (such as differential privacy) provably resist composition attacks and, in fact, the use of arbitrary side information.This resistance enables "stand-alone" design of anonymization schemes, without the need for explicitly keeping track of other releases.We provide a precise formulation of this property, and prove that an important class of relaxations of differential privacy also satisfy the property. This significantly enlarges the class of protocols known to enable modular design.
Nelder-Mead Simplex Optimization Routine for Large-Scale Problems: A Distributed Memory Implementation

The Nelder-Mead simplex method is an optimization routine that works well with irregular objective functions. For a function of $$n$$ parameters, it compares the objective function at the $$n+1$$ vertices of a simplex and updates the worst vertex through simplex search steps. However, a standard serial implementation can be prohibitively expensive for optimizations over a large number of parameters. We describe an implementation of the Nelder-Mead method in parallel using a distributed memory. For $$p$$ processors, each processor is assigned $$(n+1)/p$$ vertices at each iteration. Each processor then updates its worst local vertices, communicates the results, and a new simplex is formed with the vertices from all processors. We also describe how the algorithm can be implemented with only two MPI commands. In simulations, our implementation exhibits large speedups and is scalable to large problem sizes.
Neuroendocrine Regulation of Feminine Sexual Behavior: Lessons from Rodent Models and Thoughts About Humans

Much has been learned concerning the neuroendocrine processes and cellular mechanisms by which steroid hormones influence reproductive behaviors in rodents and other animals. In this review, a short discussion of hormones and feminine sexual behavior in some rodent species is followed by an outline of the main principles that have been learned from these studies. Examples are given of the importance of considering the timing of hormone treatments, dosage of hormone, use of a specific hormone, particular class of hormones, or form of hormone, interactions between hormones, route of administration, peripheral factors that influence hormonal response, and the possible mechanisms of action by which hormones and other factors influence sexual behaviors. Although cellular studies in humans are presently impossible to perform, mechanistic studies in rodents may provide clues about the neuroendocrine mechanisms by which hormones act and interact in the brain to influence behavior in all species, including humans.
Central Simple Algebras with Involution: A Geometric Approach

Let k be an algebraically closed base field of characteristic zero. The category equivalence between central simple algebras and irreducible, generically free PGLn-varieties is extended to the context of central simple algebras with involution. The associated variety of a central simple algebra with involution comes with an action of \({{\rm PGL}_n\rtimes\langle\tau\rangle}\), where τ is the automorphism of PGLn given by τ (h) = (h−1)transpose. Basic properties of an involution are described in terms of the action of \({{\rm PGL}_n\rtimes\langle\tau\rangle}\) on the associated variety, and in particular in terms of the stabilizer in general position for this action.
Predicting Product Purchase from Inferred Customer Similarity: An Autologistic Model Approach

Product recommendation models are key tools in customer relationship management (CRM). This study develops a product recommendation model based on the principle that customer preference similarity stemming from prior purchase behavior is a key element in predicting current product purchase. The proposed recommendation model is dependent on two complementary methodologies: joint space mapping (placing customers and products on the same psychological map) and spatial choice modeling (allowing observed choices to be correlated across customers). Using a joint space map based on past purchase behavior, a predictive model is calibrated in which the probability of product purchase depends on the customer's relative distance to other customers on the map. An empirical study demonstrates that the proposed approach provides excellent forecasts relative to benchmark models for a customer database provided by an insurance firm.
Prenatal Exposure to the Environmental Obesogen Tributyltin Predisposes Multipotent Stem Cells to Become Adipocytes

The environmental obesogen hypothesis proposes that pre- and postnatal exposure to environmental chemicals contributes to adipogenesis and the development of obesity. Tributyltin (TBT) is an agonist of both retinoid X receptor (RXR) and peroxisome proliferator-activated receptor (PPAR). Activation of these receptors can elevate adipose mass in adult mice exposed to the chemical in utero. Here we show that TBT sensitizes human and mouse multipotent stromal stem cells derived from white adipose tissue [adipose-derived stromal stem cells (ADSCs)] to undergo adipogenesis. In vitro exposure to TBT, or the PPAR activator rosiglitazone increases adipogenesis, cellular lipid content, and expression of adipogenic genes. The adipogenic effects of TBT and rosiglitazone were blocked by the addition of PPAR antagonists, suggesting that activation of PPAR mediates the effect of both compounds on adipogenesis. ADSCs from mice exposed to TBT in utero showed increased adipogenic capacity and reduced osteogenic capacity with enhanced lipid accumulation in response to adipogenic induction. ADSCs retrieved from animals exposed to TBT in utero showed increased expression of PPAR target genes such as the early adipogenic differentiation gene marker fatty acid-binding protein 4 and hypomethylation of the promoter/ enhancer region of the fatty acid-binding protein 4 locus. Hence, TBT alters the stem cell compartment by sensitizing multipotent stromal stem cells to differentiate into adipocytes, an effect that could likely increase adipose mass over time. (Molecular Endocrinology 24: 526–539, 2010)