cssi/SciSciGPT-SciSciNet huggingface dataset:
Mena deficiency delays tumor progression and decreases metastasis in polyoma middle-T transgenic mouse mammary tumors

The actin binding protein Mammalian enabled (Mena), has been implicated in the metastatic progression of solid tumors in humans. Mena expression level in primary tumors is correlated with metastasis in breast, cervical, colorectal and pancreatic cancers. Cells expressing high Mena levels are part of the tumor microenvironment for metastasis (TMEM), an anatomical structure that is predictive for risk of breast cancer metastasis. Previously we have shown that forced expression of Mena adenocarcinoma cells enhances invasion and metastasis in xenograft mice. Whether Mena is required for tumor progression is still unknown. Here we report the effects of Mena deficiency on tumor progression, metastasis and on normal mammary gland development. To investigate the role of Mena in tumor progression and metastasis, Mena deficient mice were intercrossed with mice carrying a transgene expressing the polyoma middle T oncoprotein, driven by the mouse mammary tumor virus. The progeny were investigated for the effects of Mena deficiency on tumor progression via staging of primary mammary tumors and by evaluation of morbidity. Stages of metastatic progression were investigated using an in vivo invasion assay, intravital multiphoton microscopy, circulating tumor cell burden, and lung metastases. Mammary gland development was studied in whole mount mammary glands of wild type and Mena deficient mice. Mena deficiency decreased morbidity and metastatic dissemination. Loss of Mena increased mammary tumor latency but had no affect on mammary tumor burden or histologic progression to carcinoma. Elimination of Mena also significantly decreased epidermal growth factor (EGF) induced in vivo invasion, in vivo motility, intravasation and metastasis. Non-tumor bearing mice deficient for Mena also showed defects in mammary gland terminal end bud formation and branching. Deficiency of Mena decreases metastasis by slowing tumor progression and reducing tumor cell invasion and intravasation. Mena deficiency during development causes defects in invasive processes involved in mammary gland development. These findings suggest that functional intervention targeting Mena in breast cancer patients may provide a valuable treatment option to delay tumor progression and decrease invasion and metastatic spread leading to an improved prognostic outcome.
A REVIEW OF SYMMETRY ALGEBRAS OF QUANTUM MATRIX MODELS IN THE LARGE N LIMIT

This is a review article in which we will introduce, in a unifying fashion and with more intermediate steps in some difficult calculations, two infinite-dimensional Lie algebras of quantum matrix models, one for the open string sector and the other for the closed string sector. Physical observables of quantum matrix models in the large N limit can be expressed as elements of these Lie algebras. We will see that both algebras arise as quotient algebras of a larger Lie algebra. We will also discuss some properties of these Lie algebras not published elsewhere yet, and briefly review their relationship with well-known algebras like the Cuntz algebra, the Witt algebra and the Virasoro algebra. We will also review how the Yang–Mills theory, various low energy effective models of string theory, quantum gravity, string-bit models, and the quantum spin chain models can be formulated as quantum matrix models. Studying these algebras thus help us understand the common symmetry of these physical systems.
On entropy bounds and holography

We show that the holographic entropy bound for gravitational systems and the Bekenstein entropy bound for nongravitational systems are holographically related. Using the AdS/CFT correspondence, we find that the Bekenstein bound on the boundary is obtained from the holographic bound in the bulk by minimizing the boundary energy with respect the AdS radius or the cosmological constant. This relation may also ameliorate some problems associated with the Bekenstein bound.
Comments on the implementation of recursive procedures and blocks in ALGOL 60

Abstract : Because of the importance, from the theoretical point of view, of recursive functions and because of the growing extent and irection of application of recursion in programming research and experimental mathematics, it is worth some effort to implement recursion - given that the costs in compilation and storage requirements are not too great. The mechanism for treating recursive procedures described here is such that the costs in time and storage to procedures involved in recursion are no more than necessary for a completely general recursion mechanism for ALGOL 60. (Author)
Computing bounds on network capacity regions as a polytope reconstruction problem

We define a notion of network capacity region of networks that generalizes the notion of network capacity defined by Cannons et al. and prove its notable properties such as closedness, boundedness and convexity when the finite field is fixed. We show that the network routing capacity region is a computable rational polytope and provide exact algorithms and approximation heuristics for computing the region. We define the semi-network linear coding capacity region, with respect to a fixed finite field, that inner bounds the corresponding network linear coding capacity region, show that it is a computable rational polytope, and provide exact algorithms and approximation heuristics. We show connections between computing these regions and a polytope reconstruction problem and some combinatorial optimization problems, such as the minimum cost directed Steiner tree problem. We provide an example to illustrate our results. The algorithms are not necessarily polynomial-time.
Description of new vacuum chamber correction concept

For rapid cycled accelerators, eddy currents induced in vacuum chambers (VCs) are typically the dominant source of systematic and random field aberrations. Complex thin wall VCs are expensive and delicate where bakeout is required, as in the AGS Booster under construction. Thick wall VCs are rugged and economical but produce large eddy currents. A self-correction concept has been developed and tested which corrects automatically by transformer action, even for variable B cycles. Coils attached to the outside of the VC cancel eddy current aberrations over the entire 'good field' aperture. The correction coils follow the local contour of the VC, so large transverse VC movements are tolerated; both the aberrations and their corrections have the same displaced coordinates. Experimental results are presented for Booster correction coil designs demonstrating both self-correction and excitation by a separate power supply. Analytic results applicable to the Booster and other fast cycling accelerators are discussed. The eddy current field aberrations induced in a preproduction full-size VC inserted in an AGS Booster dipole have been successfully eliminated by the self-correction coils attached to its surface. The voltage induced in a two-turns-per-pole 'back leg' winding is sufficient to supply the necessary current through the correction winding. >
State Trading Enterprises in a Differentiated Product Environment: The Case of Global Malting Barley Markets

This study tested if the exclusive procuring and pricing policies of two state trading enterprises (STEs) in international malting barley markets could be used in a strategic trade context. The research provided four key findings. First, the global malting barley market operated in a quantity-setting oligopolistic structure during the study years. Second, both STEs and other exporting countries were in Cournot competition and thus made available strategic trade possibilities. Third, initial commodity payments were too high to generate a rent-shifting outcome. Fourth, product differentiation was confirmed, which may have dampened the desire/ability of STEs to pursue a rent-shifting objective.
The SET Domain Is Essential for Metnase Functions in Replication Restart and the 5' End of SS-Overhang Cleavage.

Metnase (also known as SETMAR) is a chimeric SET-transposase protein that plays essential role(s) in non-homologous end joining (NHEJ) repair and replication fork restart. Although the SET domain possesses histone H3 lysine 36 dimethylation (H3K36me2) activity associated with an improved association of early repair components for NHEJ, its role in replication restart is less clear. Here we show that the SET domain is necessary for the recovery from DNA damage at the replication forks following hydroxyurea (HU) treatment. Cells overexpressing the SET deletion mutant caused a delay in fork restart after HU release. Our In vitro study revealed that the SET domain but not the H3K36me2 activity is required for the 5’ end of ss-overhang cleavage with fork and non-fork DNA without affecting the Metnase-DNA interaction. Together, our results suggest that the Metnase SET domain has a positive role in restart of replication fork and the 5’ end of ss-overhang cleavage, providing a new insight into the functional interaction of the SET and the transposase domains.
Stigma and racial/ethnic HIV disparities: Moving toward resilience.

Prior research suggests that stigma plays a role in racial/ethnic health disparities. However, there is limited understanding about the mechanisms by which stigma contributes to HIV-related disparities in risk, incidence and screening, treatment, and survival and what can be done to reduce the impact of stigma on these disparities. We introduce the Stigma and HIV Disparities Model to describe how societal stigma related to race and ethnicity is associated with racial/ethnic HIV disparities via its manifestations at the structural level (e.g., residential segregation) as well as the individual level among perceivers (e.g., discrimination) and targets (e.g., internalized stigma). We then review evidence of these associations. Because racial/ethnic minorities at risk of and living with HIV often possess multiple stigmas (e.g., HIV-positive, substance use), we adopt an intersectionality framework and conceptualize interdependence among co-occurring stigmas. We further propose a resilience agenda and suggest that intervening on modifiable strength-based moderators of the association between societal stigma and disparities can reduce disparities. Strengthening economic and community empowerment and trust at the structural level, creating common ingroup identities and promoting contact with people living with HIV among perceivers at the individual level, and enhancing social support and adaptive coping among targets at the individual level can improve resilience to societal stigma and ultimately reduce racial/ethnic HIV disparities.
Metrics of positive curvature with conic singularities on the sphere

A simple proof is given of the necessary and sufficient condition on a triple of positive numbers θ 1 , θ 2 , θ 3 for the existence of a conformal metric of constant positive curvature on the sphere, with three conic singularities of total angles 2πθ 1 , 2πθ 2 , 2πθ 3 . The same condition is necessary and sufficient for the triple πθ 1 , πθ 2 , πθ 3 to be interior angles of a spherical triangular membrane.
Quasi-uniformity of minimal weighted energy points on compact metric spaces

For a closed subset K of a compact metric space A possessing an @a-regular measure @m with @m(K)>0, we prove that whenever s>@a, any sequence of weighted minimal Riesz s-energy configurations @w"N={x"i","N^(^s^)}"i"="1^N on K (for 'nice' weights) is quasi-uniform in the sense that the ratios of its mesh norm to separation distance remain bounded as N grows large. Furthermore, if K is an @a-rectifiable compact subset of Euclidean space (@a an integer) with positive and finite @a-dimensional Hausdorff measure, it is possible to generate such a quasi-uniform sequence of configurations that also has (as N->~) a prescribed positive continuous limit distribution with respect to @a-dimensional Hausdorff measure.
Macroeconomic Determinants of Private Label Penetration

Private label market share is growing. Europe, long held to be near saturation in private label share, is showing surprising strength. Eastern Europe's private label share has grown to almost 1 in every 5 dollars spent in food stores for private label, and South America and Asia are showing unexpected strength. The issue is to what extent branded manufacturers can expect private label to grow within a country. This article investigates the relationship between private label penetration within a country and various macroeconomic/environmental variables. The most significant variable was the level of retail concentration followed by the level of social and economic development.
Deconvolution of High Dimensional Mixtures via Boosting, with Application to Diffusion-Weighted MRI of Human Brain

Diffusion-weighted magnetic resonance imaging (DWI) and fiber tractography are the only methods to measure the structure of the white matter in the living human brain. The diffusion signal has been modelled as the combined contribution from many individual fascicles of nerve fibers passing through each location in the white matter. Typically, this is done via basis pursuit, but estimation of the exact directions is limited due to discretization [1,2]. The difficulties inherent in modeling DWI data are shared by many other problems involving fitting non-parametric mixture models. Ekanadaham et al. [3] proposed an approach, continuous basis pursuit, to overcome discretization error in the 1-dimensional case (e.g., spike-sorting). Here, we propose a more general algorithm that fits mixture models of any dimensionality without discretization. Our algorithm uses the principles of L2-boost [4], together with refitting of the weights and pruning of the parameters. The addition of these steps to L2-boost both accelerates the algorithm and assures its accuracy. We refer to the resulting algorithm as elastic basis pursuit, or EBP, since it expands and contracts the active set of kernels as needed. We show that in contrast to existing approaches to fitting mixtures, our boosting framework (1) enables the selection of the optimal bias-variance tradeoff along the solution path, and (2) scales with high-dimensional problems. In simulations of DWI, we find that EBP yields better parameter estimates than a non-negative least squares (NNLS) approach, or the standard model used in DWI, the tensor model, which serves as the basis for diffusion tensor imaging (DTI) [5]. We demonstrate the utility of the method in DWI data acquired in parts of the brain containing crossings of multiple fascicles of nerve fibers.
Optical Imaging with Dynamic Contrast Agents

Biological imaging applications often employ molecular probes or nanoparticles for enhanced contrast. However, resolution and detection are still often limited by the intrinsic heterogeneity of the Isample, which can produce high levels of background that obscure the signals of interest. In this article we describe approaches to overcome this obstacle based on the concept of dynamic contrast, a strategy for elucidating signals by the suppression or removal of background noise. Dynamic contrast mechanisms can greatly reduce the loading requirement of contrast agents, and may be especially useful for single-probe imaging. Dynamic contrast modalities are also platform-independent, and can enhance the performance of sophisticated biomedical imaging systems or simple optical microscopes alike. Dynamic contrast is performed in two stages: i) a signal modulation scheme to introduce time-dependent changes in amplitude or phase, and ii) a demodulation step for signal recovery. Optical signals can be coupled with magnetic nanoparticles, photoswitchable probes, or plasmon-resonant nanostructures for modulation by magnetomotive, photonic, or photothermal mechanisms respectively. With respect to image demodulation, many of the strategies developed for signal processing in electronics and communication technologies can also be applied toward the editing of digital images. The image processing step can be as simple as differential imaging, or may involve multiple reference points for deconvolution using cross-correlation algorithms. Periodic signals are particularly amenable to image demodulation strategies based on Fourier transform; the contrast of the demodulated signal increases with acquisition time, and modulation frequencies in the kHz range are possible. Dynamic contrast is an emerging topic with considerable room for development, both with respect to molecular or nanoscale probes for signal modulation, and also to methods for more efficient image processing and editing.
Monotone Approximation of Decision Problems

Many decision problems exhibit structural properties in the sense that the objective function is a composition of different component functions that can be identified using empirical data. We consider the approximation of such objective functions, subject to general monotonicity constraints on the component functions. Using a constrained B-spline approximation, we provide a data-driven robust optimization method for environments that can be sample-sparse. The method, which simultaneously identifies and solves the decision problem, is illustrated for the problem of optimal debt settlement in the credit-card industry.
Variables affecting mixed oxidant corrosion of stainless steels in gasifiers

This paper is the final installment of EPRI's project on corrosion in syngas coolers of integrated coal gasification combined cycle plant. In previous papers we explored the effect of chloride species on mixed oxidant corrosion of stainless steels (CORROSION 97, Paper 134) and iron aluminides (CORROSION 98, Paper 185). It was found that the amount of chloride species in the gas and in deposits largely determined the rate of corrosion. Armed with this understanding the effect of a few common process variables is explored in this paper. It was found that corrosion rates decline at higher temperatures, when chloride-enhanced mixed oxidant corrosion occurs at lower temperatures, but corrosion rates increase with temperature for pure sulfidation/oxidation, as may be expected. System pressure was generally of secondary importance, but again higher corrosion rates were generally experienced at elevated pressure, when chloride-enhanced corrosion was predominant, especially at lower temperatures. A simulated temperature excursion below the syngas dewpoint had similar effects, and also caused chloride-enhanced corrosion in 310 stainless steel, which usually does not show this type of corrosion, except when exposed to aqueous corrosion during downtime. A pleasant surprise was the almost complete lack of corrosion when H 2 S and HCl levels were reduced to those expected downstream from gasifiers using in-bed desulfurization. It would appear that 12Cr steels may be adequate here. This is being explored further.
Real healthcare reform: focus on primary care access.

Abstract Primary care coverage for the uninsured is the first necessary step to reform and can be more cost effective and tolerable than a major system reform. By providing foundational care to the uninsured, more care resources are targeted to those that most need the services, while providing benefits such as increased productivity and reduced inappropriate emergency department utilization. The authors aimed to design a primary care coverage system in the United States for the uninsured using established reimbursement, budgeting, and compliance methods. Providing four primary care visits for acute care, four associated ancillary and four fulfilled pharmaceutical–treatment prescriptions, and one preventive primary care visit per year for nearly 48,000,000 uninsured would cost $36 per month for every working American and legal alien resident. Theoretical and empirical literature was reviewed and the authors applied practical knowledge based on their experience in healthcare systems to develop the Access A...
The bandwidth exchange architecture

New applications for the Internet such as video on demand, grid computing etc. depend on the availability of high bandwidth connections with acceptable quality of service (QoS). There appears to be, therefore, a requirement for a market where bandwidth-related transactions can take place. For this market to be effective, it must be efficient for both the provider (seller) and the user (buyer) of the bandwidth. This implies that: (a) the buyer must have a wide choice of providers that operate in a competitive environment, (b) the seller must be assured that a QoS transaction will be paid by the customer, and (c) the QoS transaction establishment must have low overheads so that it may be used by individual customers without a significant burden to the provider. In order to satisfy these requirements, we propose a framework that allows customers to purchase bandwidth using an open market where providers advertise links and capacities and customers bid for these services. The model is close to that of a commodities market that offers both advance bookings (futures) and a spot market. We explore the mechanisms that can support such a model.
Orientation-Independent Differential Interference Contrast Microscopy

We describe a new technique for differential interference contrast (DIC) microscopy, which digitally generates phase gradient images independently of gradient orientation. To prove the principle we investigated specimens recorded at different orientations on a microscope equipped with a precision rotating stage and using regular DIC optics. The digitally generated images successfully displayed and measured phase gradients, independently of gradient orientation. One could also generate images showing distribution of optical path differences or enhanced, regular DIC images with any shear direction. Using special DIC prisms, one can switch the bias and shear directions rapidly without mechanically rotating the specimen or the prisms and orientation-independent DIC images are obtained in a fraction of a second.
Systematization of Approaches to Adaptive Boundary Stabilization of PDEs

While adaptive control of finite dimensional systems is an advanced field that has produced adaptive control methods for a very general class of LTI systems, adaptive control techniques have been developed for only a few of the classes of PDEs for which non-adaptive controllers exist. We present a catalog of approaches for the design of adaptive controllers for PDEs controlled from a boundary and containing unknown destabilizing parameters affecting the interior of the domain. We differentiate between two major classes of schemes: Lyapunov schemes and certainty equivalence schemes. Within the certainty equivalence class, two types of identifier designs are pursued: passivity-based and swapping designs. Each of those designs is applicable to two types of parametrizations: the plant model in its original form (which we refer to as the "u-model") and a transformed model to which a backstepping transformation has been applied (which we refer to as the "w-model"). Hence, a large number of control algorithms result from combining different design tools - Lyapunov schemes, w-passive schemes, u-swapping schemes, etc. Our method builds upon the explicitly parametrized control formulae that we introduced in our earlier work on non-adaptive backstepping control for PDEs. These formulae allow us to develop tunable controllers that avoid solving Riccati or Bezout equations at each time step
Experiment, thermal simulation, and characterizations on transmission laser coating of hydroxyapatite on metal implant.

Coating of bioceramic material, Hydroxyapatite (HAp), on metal implant has attracted many attentions in biomedical industry recently because its combination of good mechanical property and biocompatibility. However, most of current HAp coatings lack coating/substrate interfacial strength, and/or biocompatibility. The cell-tissue attachment is affected by the degraded biocompatibility due to decomposition of HAp during high temperature processing. In this article, an innovative method, transmission laser coating (TLC), is investigated to coat HAp on Ti substrate with low temperature processing. This process enhances the HAp/Metal interfacial property of current coatings, while maintaining good biocompatibility. Experiments are conducted using a continuous neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. Multiphysics simulation is conducted to simulate the temperature distribution in coatings and substrates during TLC processing. X-ray energy dispersion spectrum is used to measure the chemical composition of HAp coatings after TLC process. Pull-out tests are conducted to measure the interfacial strength between the HAp coating and Ti substrate. Cell culture study is conducted to qualitatively evaluate the biocompatibility after TLC of HAp particles. These results show that TLC processing will open new ways of producing biocompatible bioceramic coatings with controlled thickness, and at low processing temperature. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Stability and Vulnerability of the Latin American Middle Class

Using panel data-sets from Mexico and Chile for the first years of the 21st century, the authors examine the determinants of middle-class intra-generational mobility. The middle class is defined by means of a latent index of economic well-being that is less sensitive to short-term fluctuation and measurement error than standard measures of income. The authors find high rates of both upward and downward mobility in Mexico and Chile, indicating that the middle class has opportunities to move to higher levels of well-being but is also vulnerable to falling into poverty. In both countries, labour-market resources (education and occupational status of the household head and number of members in the labour market) are much stronger determinants of mobility than demographic factors, suggesting the importance of policies that foster human capital and protect workers from shocks. Rural middle-class households are substantially more vulnerable to falling into poverty and have little chance of advancing to upper cla...
Optimal Estimation on the Graph Cycle Space

This paper addresses the problem of estimating the states of a group of agents from noisy measurements of pairwise differences between agents' states. The agents can be viewed as nodes in a graph and the relative measurements between agents as the graph's edges. We propose a new distributed algorithm that exploits the existence of cycles in the graph to compute the best linear state estimates. For large graphs, the new algorithm significantly reduces the total number of message exchanges that are needed to obtain an optimal estimate. We show that the new algorithm is guaranteed to converge for planar graphs and provide explicit formulas for its convergence rate for regular lattices.
Convergent synthesis of a steroidal antiestrogen-mitomycin C hybrid using "click" chemistry.

A convergent synthesis of a novel estrogen receptor-targeted drug hybrid was developed based on structures of the potent anti-proliferative mitomycin C and the steroidal anti-estrogen RU 39411. The steroidal antiestrogen was prepared with an azido-triethylene glycoloxy linker while the mitomycin C derivative (porfirimycin) incorporated a complementary 7-N-terminal alkyne. The two components were ligated using the Huisgen [3 + 2] cycloaddition (“click”) reaction. Preliminary biological assays demonstrated that the final hybrid compound retained both potent anti-estrogenic and anti-proliferative activities.
Spherical Hamiltonian Monte Carlo for Constrained Target Distributions

Statistical models with constrained probability distributions are abundant in machine learning. Some examples include regression models with norm constraints (e.g., Lasso), probit models, many copula models, and Latent Dirichlet Allocation (LDA) models. Bayesian inference involving probability distributions confined to constrained domains could be quite challenging for commonly used sampling algorithms. For such problems, we propose a novel Markov Chain Monte Carlo (MCMC) method that provides a general and computationally efficient framework for handling boundary conditions. Our method first maps the D-dimensional constrained domain of parameters to the unit ball B0D (1), then augments it to a D-dimensional sphere SD such that the original boundary corresponds to the equator of SD. This way, our method handles the constraints implicitly by moving freely on the sphere generating proposals that remain within boundaries when mapped back to the original space.
Kinetics and products of the gas‐phase reactions of the OH radical and O3 with allyl chloride and benzyl chloride at room temperature

The kinetics of the gas-phase reactions of allyl chloride and benzyl chloride with the OH radical and O3 were investigated at 298 ± 2 K and atmospheric pressure. Direct measurements of the rate constants for reactions with ozone yielded values of (O3 + allyl chloride) = (1.60 ± 0.18) × 10−18 cm3 molecule−1 s−1 and (O3 + benzyl chloride) < 6 × 10−20 cm3 molecule−1 s−1. With the use of a relative rate technique and ethane as a scavenger of chlorine atoms produced in the OH radical reactions, rate constants of (OH + allyl chloride) = (1.69 ± 0.07) × 10−11 cm3 molecule−1 s−1 and (OH + benzyl chloride) = (2.80 ± 0.19) × 10−12 cm3 molecule−1 s−1 were measured. A study of the OH radical reaction with allyl chloride by long pathlength FT-IR absorption spectroscopy indicated that the co-products ClCH2CHO and HCHO account for ca. 44% of the reaction, and along with the other products HOCH2CHO, (ClCH2)2CO, and CH2 CHCHO account for 84 ± 16% of the allyl chloride reacting. The data indicate that in one atmosphere of air in the presence of NO the chloroalkoxy radical formed following OH radical addition to the terminal carbon atom of the double bond decomposes to yield HOCH2CHO and the CH2Cl radical, which becomes a significant source of the Cl atoms involved in secondary reactions. A product study of the OH radical reaction with benzyl chloride identified only benzaldehyde and peroxybenzoyl nitrate in low yields (ca. 8% and ⩽4%, respectively), with the remainder of the products being unidentified.
Role of Software in Spacecraft Accidents

The first and most important step in solving any problem is understanding the problem well enough to create effective solutions. To this end, several software-related spacecraft accidents were studied to determine common systemic factors. Although the details in each accident were different, very similar factors related to flaws in the safety culture, the management and organization, and technical deficiencies were identified. These factors include complacency and discounting of software risk, diffusion of responsibility and authority, limited communication channels and poor information flow, inadequate system and software engineering (poor or missing specifications, unnecessary complexity and software functionality, software reuse without appropriate safety analysis, violation of basic safety engineering practices in the digital components), inadequate review activities, ineffective system safety engineering, flawed test and simulation environments, and inadequate human factors engineering. Each of these factors is discussed along with some recommendations on how to eliminate them in future projects.
Bidentate NHC-based chiral ligands for efficient Cu-catalyzed enantioselective allylic alkylations: structure and activity of an air-stable chiral Cu complex.

Cu-catalyzed addition of alkylzinc reagents to a range of allylic phosphates is promoted efficiently and with high enantioselectivity to afford tertiary as well as quaternary carbon centers (up to 98% ee). Reactions proceed to completion with 0.5−5 mol % catalyst loading and are best promoted by commercially available CuCl2·2H2O. The X-ray structure of the chiral NHC−Ag(I) complex used in the study as well as that of a catalytically active NHC−Cu(II) complex are also reported; both complexes are air-stable and are formed in ≥95% isolated yield. The isolated Cu complex, which can be handled in air, is catalytically active. The present report provides the first precedent for efficient Cu-catalyzed allylic alkylations with chiral NHC ligands.
Morphological Control of Electrospun Nafion Nanofiber Mats

There are a number of electrochemical and electromechanical applications where it is desirable to electrospin Nafion into nanofibers, including composite fuel cell membranes, sensors, and polymer-based actuators. Nafion and other perfluorosulfonic acid polymers, however, are notoriously difficult to electrospin and require the presence of a high molecular weight carrier polymer in the electrospinning solution. In this paper, we report on the morphology of electrospun Nafion nanofiber mats that are created using a low concentration (1-2 wt %) of poly(ethylene oxide) (PEO) as the carrier polymer. The effects of electrospinning conditions, i.e., air humidity, polymer solution solvent, carrier polymer molecular weight, electrospinning voltage, and electrospinning flow rate, on the quality of the electrospun mat (i.e., the presence/absence of unwanted bead or bead-on-fiber morphologies) and the mat-averaged nanofiber diameter are presented and discussed. Bead-on-fiber structures are more prevalent when Nafion is electrospun at high humidity conditions and when the applied voltage is high. Ribbon-like morphologies form when a high molecular weight PEO carrier polymer is used. Nafion/PEO fiber diameter depends strongly on air humidity, solution solvent, carrier polymer molecular weight, and electrospinning flow rate, where the average diameter of well-formed Nafion/PEO nanofibers can be easily varied from 300 to 900 nm.
Optimizing P,N‐Bidentate Ligands for Oxidative Gold Catalysis: Efficient Intermolecular Trapping of α‐Oxo Gold Carbenes by Carboxylic Acids

Steric Bulk or Conformation Control? Optimization of P,N-bidentate ligands reveals the importance of conformation control in the development of highly efficient intermolecular trapping of reactive α-oxo gold carbene intermediates. While a pendant piperidine ring offers suitable steric bulk, fixing its conformation to provide better shielding to the highly electrophilic carbene center turned out to be crucial for the excellent reaction efficiency. A generally highly efficient and broadly applicable synthesis of carboxymethyl ketones from readily available carboxylic acids and terminal alkynes is developed under exceptionally mild reaction conditions.
Nucleoside synthesis from thioglycosides

Abstract Acetylated phenyl and methyl 1-thiofurano- and pyranosides react with silylated uracil, acetylcytosine, and benzoyladenine under the influence of NIS / triflic acid to generate the β-nucleoside derivatives in good yield.
SLIVER REMOVAL BY LATTICE REFINEMENT

I present an algorithm that can create a mesh that is free of slivers away from the boundary, or that can eliminate such slivers from a pre-existing mesh by refining it. The resulting tetrahedra have dihedral angles between 30 and 135 degrees and radius-edge ratios of at most 1.368, except near the boundary. In comparison, previous bounds on dihedral angles were microscopic. The final mesh can respect specified input vertices and a user-defined sizing function. The algorithm comes with a bound on the sizes of the features it creates, and can provably grade from small to large tetrahedra.
A note on the effective soft SUSY-breaking Lagrangian below the GUT scale

I consider the superfield derivation of the effective theory of softly broken supersymmetry below the GUT scale. I point out the role of supergauge invariance in determining the form of the result, which is rather restricted in interesting classes of models. As an example I discuss sfermion mass splittings for matter embedded in a single GUT multiplet. Interesting differences arise between the cases of SU(5), SO(10) and E(6).
Uncertainty and Political Perceptions

While the world of politics is uncertain, previous work, both theoretical and empirical, has largely failed to incorporate this uncertainty into the analysis of public opinion and electoral behavior. In this article we discuss measures designed to elicit the uncertainty survey respondents feel about their political perceptions. These measures exhibit response patterns which are interpretable, substantively interesting, and consistent with a model relating uncertainty to citizen information costs. We also find that variation in respondent uncertainty leads to different models of perception of political figures and speaks to models of the survey response. As a practical matter, our measures can easily be incorporated into existing surveys with no disruption of continuity.
Mobility control and its applications in mobile ad hoc networks

Most existing localized protocols in mobile ad hoc networks, such as data communication and topology control, use local information for decentralized decision among nodes to achieve certain global objectives. These objectives include determining a small connected dominating set for virtual backbone and topology control by adjusting transmission ranges of nodes. Because of asynchronous sampling of local information at each node, delays at different stages of protocol handshake, and movement of mobile nodes, the local view captured at different nodes many be inconsistent and/or outdated and many not reflect the actual network situation. The former may cause "bad" decisions that fail to keep the given global constraint such as global domination and connectivity, and the latter may incur "broken" links, which in turn would ultimately cause the failure of the constraint. In this article we review some techniques that handle inconsistent and outdated local views. These techniques are illustrated using several well-known protocols in data communication and topology control.
Finite-Gap Solutions of the Vortex Filament Equation: Isoperiodic Deformations

We study the topology of quasiperiodic solutions of the vortex filament equation in a neighborhood of multiply covered circles. We construct these solutions by means of a sequence of isoperiodic deformations, at each step of which a real double point is "unpinched" to produce a new pair of branch points and therefore a solution of higher genus. We prove that every step in this process corresponds to a cabling operation on the previous curve, and we provide a labelling scheme that matches the deformation data with the knot type of the resulting filament.
Synthesis of substituted butenolides by the ring closing metathesis of two electron deficient olefins: a general route to the natural products of paraconic acids class ☆

Abstract A variety of allyl acrylates possessing electron-withdrawing groups undergo RCM using the second generation Grubbs’ catalyst in the presence of a Lewis acid resulting in diverse butenolides in high isolated yields. This methodology provides a general route to the natural products of paraconic acids class, exemplified by a total synthesis of (±)-phaseolinic acid.
Diastereoselective oxidation of substituted 1,2-dithiolan-3-ones

Abstract Oxidation of 1,2-dithiolan-3-ones 1 with one equivalent of dimethyldioxirane in dichloromethane at −78°C produces the corresponding 1,2-dithiolan-3-one 1-oxides 2 in high yield and with diastereoselectivities as high as 18:1. The major diastereomer formed is the trans isomer. An X-ray crystallographic structure study of the major diastereomer 2c obtained by oxidation of 1g is reported.
Tropical Atlantic climate response to low‐latitude and extratropical sea‐surface temperature: A Little Ice Age perspective

[1] Proxy reconstructions and model simulations suggest that steeper interhemispheric sea surface temperature (SST) gradients lead to southerly Intertropical Convergence Zone (ITCZ) migrations during periods of North Atlantic cooling, the most recent of which was the Little Ice Age (LIA; ∼100–450 yBP). Evidence suggesting low-latitude Atlantic cooling during the LIA was relatively small (<1°C) raises the possibility that the ITCZ may have responded to a hemispheric SST gradient originating in the extratropics. We use an atmospheric general circulation model (AGCM) to investigate the relative influence of low-latitude and extratropical SSTs on the meridional position of the ITCZ. Our results suggest that the ITCZ responds primarily to local, low-latitude SST anomalies and that small cool anomalies (<0.5°C) can reproduce the LIA precipitation pattern suggested by paleoclimate proxies. Conversely, even large extratropical cooling does not significantly impact low-latitude hydrology in the absence of ocean-atmosphere interaction.
STUDIES IN ASTRONOMICAL TIME SERIES ANALYSIS. VI. BAYESIAN BLOCK REPRESENTATIONS

This paper addresses the problem of detecting and characterizing local variability in time series and other forms of sequential data. The goal is to identify and characterize statistically significant variations, at the same time suppressing the inevitable corrupting observational errors. We present a simple nonparametric modeling technique and an algorithm implementing it—an improved and generalized version of Bayesian Blocks [Scargle 1998]—that finds the optimal segmentation of the data in the observation interval. The structure of the algorithm allows it to be used in either a real-time trigger mode, or a retrospective mode. Maximum likelihood or marginal posterior functions to measure model fitness are presented for events, binned counts, and measurements at arbitrary times with known error distributions. Problems addressed include those connected with data gaps, variable exposure, extension to piecewise linear and piecewise exponential representations, multi-variate time series data, analysis of variance, data on the circle, other data modes, and dispersed data. Simulations provide evidence that the detection efficiency for weak signals is close to a theoretical asymptotic limit derived by [Arias-Castro, Donoho and Huo 2003]. In the spirit of Reproducible Research [Donoho et al. (2008)] all of the code and data necessary to reproduce all of the figures in this paper are included as auxiliary material.
Error-Correction Capability of Column-Weight-Three LDPC Codes

In this paper, the error-correction capability of column-weight-three low-density parity-check (LDPC) codes when decoded using the Gallager A algorithm is investigated. It is proved that a necessary condition for a code to correct all error patterns with up to k ges 5 errors is to avoid cycles of length up to 2k in its Tanner graph. As a consequence of this result, it is shown that given any alpha > 0, exist N such that forall n > N, no code in the ensemble of column-weight-three codes can correct all alphan or fewer errors. The results are extended to the bit flipping algorithms.
Molecular Genetics of Colorectal Cancer

Over the past three decades, molecular genetic studies have revealed some critical mutations underlying the pathogenesis of the sporadic and inherited forms of colorectal cancer (CRC). A relatively limited number of oncogenes and tumor-suppressor genes—most prominently the APC, KRAS, and p53 genes—are mutated in a sizeable fraction of CRCs, and a larger collection of genes that are mutated in subsets of CRC have begun to be defined. Together with DNA-methylation and chromatin-structure changes, the mutations act to dysregulate conserved signaling networks that exert context-dependent effects on critical cell phenotypes, including the regulation of cellular metabolism, proliferation, differentiation, and survival. Much work remains to be done to fully understand the nature and significance of the individual and collective genetic and epigenetic defects in CRC. Some key concepts for the field have emerged, two of which are emphasized in this review. Specifically, the gene defects in CRC often target protein...
Size, Value, and Momentum in International Stock Returns §

In the four regions (North America, Europe, Japan, and Asia Pacific) we examine, there are value premiums in average stock returns that, except for Japan, decrease with size. Except for Japan, there is return momentum everywhere, and spreads in average momentum returns also decrease from smaller to bigger stocks. We test whether empirical asset pricing models capture the value and momentum patterns in international average returns and whether asset pricing seems to be integrated across the four regions. Integrated pricing across regions does not get strong support in our tests. For three regions (North America, Europe, and Japan), local models that use local explanatory returns provide passable descriptions of local average returns for portfolios formed on size and value versus growth. Even local models are less successful in tests on portfolios formed on size and momentum.
Computing stable poses of piecewise smooth objects

Abstract When a three dimensional object is known to be lying on a planar surface, its pose is restricted from six to three degrees of freedom. Computer vision algorithms can exploit the few stable poses of modeled objects to simplify scene interpretation and more accurately determine object location. This paper presents necessary and sufficient conditions for the pose of a piecewise smooth curved three-dimensional object to be stable. For objects whose surfaces are represented by implicit algebraic equations, these conditions can be expressed as systems of polynomial equations that are readily solved by homotopy continuation. Examples from the implemented algorithm are presented.
Palladium‐Catalyzed Oxidative Wacker Cyclizations in Nonpolar Organic Solvents with Molecular Oxygen: A Stepping Stone to Asymmetric Aerobic Cyclizations

A variety of Pd-catalyzed oxidative nucleophile/alkene cyclizations proceeds in excellent yield under simple aerobic conditions in nonpolar media (Pd catalyst, pyridine, and O_2 in toluene). Nucleophiles for these cyclizations include phenols, carboxylic acids, amides, and primary alcohols. Additionally, enantioselective catalysis is feasible with a Pd-sparteine system (see picture). Enantioselectivities of up to 90 % ee are observed for simple phenol/alkene cyclizations.
On the Risk of Stocks in the Long Run

A familiar proposition is that investing in common stocks is less risky the longer an investor plans to hold them. If this proposition were true, then the cost of insuring against earning less than the risk-free rate of interest should decline as the investment horizon lengthens. This paper shows that the opposite is true, even if stock returns are mean reverting in the long run. The case for young people investing more heavily than older people in stocks cannot, therefore, rest solely on the long-run properties of stock returns. For guarantors of money-fixed annuities, the proposition that stocks in their portfolios are a better hedge the longer the maturity of their obligations is unambiguously wrong.
Stacking fault energy of 6H-SiC and 4H-SiC single crystals

Abstract Single crystal 4H and 6H polytypes of SiC have been deformed in compression at 1300°C. All the deformation-induced dislocations were found to be dissociated into two partials bounding a ribbon of intrinsic stacking fault. Using two-beam bright-field and weak-beam dark-field techniques of transmission electron microscopy, the stacking fault energy of these two SiC polytypes has been determined from the separation width of the two partials of dissociated dislocations. The stacking fault energy of 4H-SiC is determined to be 14.7±2.5mJm−2, and that of 6H-SiC to be 2.9±0.6mJm−2. As a verification, the stacking fault energy of 4H-SiC has been determined also from the minimum radius of curvature of extended nodes. This latter method gave a value of 12.2±1.1mJm−2 which is within the range determined from measurement of partial dislocation separations. The experimental values of stacking fault energy for 4H- and 6H-SiC have been compared with estimates obtained from a generalized axial next-nearest-neighb...