cssi/SciSciGPT-SciSciNet huggingface dataset:
Predicting productivity gains from parking behavior

Purpose – The purpose of this paper is to use parking behavior as a direct measure of delayed gratification, a cultural trait recognized by scholars as contributing to people's economic success. Backing into a parking space requires more time and effort, but it will enable the driver to exit more easily, safely, and quickly in the future. The author argue that people who park their cars back-in embody a culture of delayed gratification, and societies with a higher back-in parking rate tend to have better economic performance. Design/methodology/approach – The author tested the hypothesis using parking and economic data from the BRIC countries, Taiwan, and the USA. Findings – Results show that there is a strong positive relationship between back-in parking and labor productivity gains. The author also found that back-in parking positively correlates with economic growth, savings rate, and educational attainment. Originality/value – This is the first study that uses parking behavior to predict economic perf...
A Calorimetric Test for Kerr Black Holes in Gamma-Ray Bursts

Cosmological gamma-ray bursts are potentially associated with systems harboring a rotating black hole. Calorimetry on yet "unseen" emissions in gravitational waves from a surrounding torus may provide a measure for its rotational energy. We introduce a compactness parameter α = 2π f dE for the fluence E and frequency f in gravitational waves. For black hole-torus systems, α 2πEf 0.005-0.05 may exceed the upper bound α* = 0.005 for rapidly rotating neutron stars. A duration in gravitational radiation consistent with the redshift-corrected durations of the BATSE catalog defines an association with long gamma-ray bursts. This promises to be a new test for Kerr black holes as objects in nature.
ADJUSTMENT COSTS, LEARNING-BY-DOING, AND TECHNOLOGY ADOPTION UNDER UNCERTAINTY

We consider a variety of vintage capital models of a firm?s choice of technology under uncertainty in the presence of adjustment costs and technology-specific learning. Similar models have been studied in a deterministic setting. Part of our objective is to examine the robustness of the implications of the certainty models to uncertainty. We find that the answer crucially depends on the specification of the costs of adoption of a new vintage of technology. In particular, if the cost comes only in terms of accumulated technology-specific expertise (cf. Parente (1994)), we demonstrate that the implications are robust for a variety of specifications of the firm?s production function. However, once we develop a model in which each adoption requires a capital expenditure, predictions become increasingly di?erent as uncertainty increases. The model implies that in booms, the firm accelerates adoptions of new technologies, delaying them in recessions. Adverse e?ects of a recession on the investment decisions are alleviated in part by the firm?s expertise (or human capital). Compared to the deterministic benchmark, the firm increases the pace of adoptions, making a smaller technological advance each time it upgrades its technology. Overall, uncertainty negatively impacts growth and the firm value.
Synthesis and properties of size-expanded DNAs: toward designed, functional genetic systems.

We describe the design, synthesis, and properties of DNA-like molecules in which the base pairs are expanded by benzo homologation. The resulting size-expanded genetic helices are called xDNA (“expanded DNA”) and yDNA (“wide DNA”). The large component bases are fluorescent, and they display high stacking affinity. When singly substituted into natural DNA, they are destabilizing because the benzo-expanded base pair size is too large for the natural helix. However, when all base pairs are expanded, xDNA and yDNA form highly stable, sequence-selective double helices. The size-expanded DNAs are candidates for components of new, functioning genetic systems. In addition, the fluorescence of expanded DNA bases makes them potentially useful in probing nucleic acids.
From HCQIA to the ACA: The Evolution of Reporting as a Quality Improvement Tool

Twenty-five years ago, after concluding that “[t]he increasing occurrence of medical malpractice and the need to improve the quality of medical care have become nationwide problems,” Congress passe...
INDUSTRIAL POLICY: DON'T ASK WHY, ASK HOW

The theoretical case for industrial policy is a strong one. The market failures which industrial policies target — in markets for credit, labor, products, and knowledge — have long been at the core...
Spatial analysis of EEG

Summary form only given. An overview and evaluation of various methods of spatial analysis of EEG and evoked potentials are presented. Topics include multiple scales of neural sources, spline-generated surface Laplacians, and representation of surface potentials by orthogonal functions. >
Asymmetric hydrogenation of itaconic acid and enol acetate derivatives with the Rh-TangPhos catalyst.

The Rh-TangPhos catalyst has been used for asymmetric hydrogenation of itaconic acid and enol acetate derivatives. A variety of chiral 2-substituted succinic acids and chiral acetates have been obtained in excellent ee values (up to 99% ee).
Completion of Standard-like Embeddings

Abstract Inequivalent standard-like observable sector embeddings in Z 3 orbifolds with two discrete Wilson lines, as determined by Casas, Mondragon, and Munoz, are completed by examining all possible ways of embedding the hidden sector. The hidden sector embeddings are relevant to twisted matter in nontrivial representations of the Standard Model and to scenarios where supersymmetry breaking is generated in a hidden sector. We find a set of 175 models which have a hidden sector gauge group which is viable for dynamical supersymmetry breaking. Only four different hidden sector gauge groups are possible in these models.
Arylalkylcarbenes from triplet arylalkyldiazoalkanes

Abstract Inter- and intramolecular triplet sensitization of two 1,2-diaryldiazoethanes in methanol gives rise to stilbenes 3 and ether 5 by intramolecular 1,2-H shifts and intermolecular reaction with methanol, respectively. The sensitized results were compared with those obtained from direct photolysis to determine the relative importance of excited state reactivity of the diazo precursors.
New Products, Sales Promotions, and Firm Value: The Case of the Automobile Industry

Abstract Year after year, managers strive to improve financial performance and firm value through marketing actions such as new product introductions and promotional incentives. This study investigates the short- and long-term impact of such marketing actions on financial metrics, including top-line, bottom-line, and stock market performance. The authors apply multivariate time-series models to the automobile industry, in which both new product introductions and promotional incentives are considered important performance drivers. Notably, whereas both marketing actions increase top-line firm performance, their long-term effects strongly differ for the bottom line. First, new product introductions increase long-term financial performance and firm value, but promotions do not. Second, investor reaction to new product introduction grows over time, indicating that useful information unfolds in the first two months after product launch. Third, product entry in a new market yields the highest top-line, bottom-l...
Explicit versus Implicit Contracts: The Case of DIFF and CROSS Futures

This paper investigates the potential success of an explicit futures contract when an implicit one, which can duplicate it, exists. It is hypothesized that the success of the explicit futures contract depends on its value added being greater than that of its implicit counterpart given that sufficient hedging demand exists for it. Following a discussion of value added analysis, hedging effectiveness of the Euro-rate Differential (DIFF), the Currency Cross-rate (CROSS) futures contracts, and their implicit counterparts are calculated and tests of relative hedging effectiveness of these contracts are performed. Test results support the hypothesis of the paper and their implications for new futures contract development are discussed.
CD44/CD24 expression in recurrent gastric cancer: a retrospective analysis.

To correlate CD44/CD24 expression with gastric cancer recurrence and prognosis. Gastric cancer is the second leading cause of cancer mortality due to the high recurrence rate, of which the molecular signature has not yet been identified. We retrospectively reviewed the hospital records of patients with gastric cancer. Among 500 patients receiving curative resection, 95 patients had recurrence. Twenty patients from the recurrence group (95 patients) and 20 patients from the non-recurrence group (405 patients) were randomly selected and identified as “study” and “control” groups, respectively. We reviewed patients’ histological study of CD44/CD24 expression by performing immunohistochemistry and recurrence rate. Study group had higher TNM stage (III-IV) than control group (80% vs. 25%, P = 0.001). Proportion of lymph node metastasis was significantly higher in study group than that in control group (90% vs. 45%, P = 0.002), and proportion of patients with 5 or more metastatic lymph nodes was also significantly higher in study group than in control group (45% vs. 15%, P = 0.007). Univariate analysis revealed no difference in risk of gastric cancer recurrence between CD44+ and CD44- patients (OR = 1.00, 95% CI: 0.29-3.45, P =1.000). CD24+ patients showed no greater significance of gastric cancer recurrence than CD24- patients (OR = 1.86, 95% CI: 0.52-6.61, P = 0.339). After adjusting for other risk factors, the association of CD44 expression (aOR = 0.66, 95% CI: 0.10-4.26, P = 0.658), CD24 expression (aOR = 0.09, 95% CI: 0.01-1.35, P = 0.081) or combined (CD44/CD24) with gastric cancer recurrence were not significant. Neither individual expression of CD24 or CD44, nor combined expression of CD44/CD24 was associated with recurrence of gastric carcinoma.
Was a Pyrimidine‐Pyrimidine Base Pair the Ancestor of Watson‐Crick Base Pairs? Insights from a Systematic Approach to the Origin of RNA

Uncovering the origin of RNA is essential for understanding the origins of life. The persistent inability of chemists to identify a plausible prebiotic route to RNA polymers, along with the seemingly optimal structure of RNA for its functions in extant life, argue in favor of the hypothesis that RNA is a product of chemical or biological evolution. To understand the origin of RNA, we must consider which molecules could have originally acted in place of RNA’s substructures (i.e., nucleobases (the recognition units), ribose (a trifunctional connector), and phosphate (an ionized linker)) in the oldest ancestor of RNA (or proto-RNA). Major challenges to uncovering the chemical structure of proto-RNA include finding molecules that would have spontaneously undergone molecular selection and covalent assembly into an RNA-like polymer, within the complex mixture of the “prebiotic soup” and without the aid of enzymes. In this review, we discuss progress towards identifying the recognition units of proto-RNA and mechanisms by which the ancestral nucleobases might have been originally selected and incorporated into polymers. We consider possible proto-nucleobases within the chemical space of the heterocycles defined by the purines and pyrimidines that have H, NH2, or O as exocyclic groups (which includes the extant nucleobases). Taking into account the results of numerous experiments that have explored nucleic acids with alternative backbones and noncanonical nucleobases, we are able to remove about half of these 81 molecules from candidacy as ancestral nucleobases. A particularly encouraging result of this approach is the identification of two molecules, 2,4,6-triaminopyrimidine and barbituric acid, which look very promising as possible nucleobases of proto-RNA.
DNA-based patterning of tethered membrane patches

Solid-supported lipid bilayers are useful model systems for mimicking cellular membranes; however, the interaction of the bilayer with the surface can disrupt the function of integral membrane proteins and impede topological transformations such as membrane fusion. As a result, a variety of tethered or cushioned lipid bilayer architectures have been described, which retain the proximity to the surface, enabling surface-sensitive techniques, but physically distance the bilayer from the surface. We have recently developed a method for spatially separating a lipid bilayer from a solid support using DNA lipids. In this system, a DNA strand is covalently attached to a glass slide or SiO2 wafer, and giant unilamellar vesicles (GUVs) displaying the complement rupture to form a planar lipid bilayer tethered above the surface. However, the location of the patch is random, determined by where the DNA-GUV initially binds to its complement. To allow greater versatility and control, we sought a way to pattern tethered membrane patches. We present a method for creating spatially distinct tethered membrane patches on a glass slide using microarray printing. Surface-reactive DNA sequences are spotted onto the slide, incubated to covalently link the DNA to the surface, and DNA-GUVs patches are formed selectively on the printed DNA. By interfacing the bilayers with microfluidic flow cells, materials can be added on top of or fused into the membrane to change the composition of the bilayers. With further development, this approach would enable rapid screening of different patches in protein binding assays and would enable interfacing patches with electrical detectors.
Vertex implications of stability for a class of delay-differential interval system

Although vertex implication in parameter space does not hold for stability of general delay-differential interval system, it is shown that in an important special case when the characteristic equation of the system is describable by certain quasi-polynomials the vertex implication for stability does hold. It is also pointed out that vertex implication for stability does not hold in general for delay-differential systems with interval delay. >
Finite Approximations of Switched Homogeneous Systems for Controller Synthesis

In this note, we demonstrate the use of a control oriented notion of finite state input/output approximation to synthesize correct-by-design controllers for hybrid plants under sensor limitations. Specifically, we consider the problem of designing stabilizing switching controllers for a pair of unstable homogeneous second order systems with binary output feedback. In addition to yielding a deterministic finite state approximate model of the hybrid plant, our approach allows one to efficiently establish a useable upper bound on the quality of approximation, and leads to a discrete optimization problem whose solution immediately provides a certified finite state controller for the plant. The resulting controller consists of a deterministic finite state observer and a corresponding full state feedback control law.
Non-invasive interactive visualization of dynamic architectural environments

We present a system for interactively producing exploded views of 3D architectural environments such as multi-story buildings. These exploded views allow viewers to simultaneously see the internal and external structures of such environments. To create an exploded view we analyze the geometry of the environment to locate individual stories. We then use clipping planes and multipass rendering to separately render each story of the environment in exploded form. Our system operates at the graphics driver level and therefore can be applied to existing OpenGL applications, such as first-person multi-player video games, without modification. The resulting visualization allows users to understand the global structure of architectural environments and to observe the actions of dynamic characters and objects interacting within such environments.
An electronically tunable microstrip bandpass filter using thin-film Barium-Strontium-Titanate (BST) varactors

A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm.
AN EMPIRICAL MODEL OF LEARNING UNDER AMBIGUITY: THE CASE OF CLINICAL TRIALS*

In this paper, I present an empirical model of learning under ambiguity in the context of clinical trials. Patients are concern with learning the treatment effect of the experimental drug, but face the ambiguity of random group assignment. A two dimensional Bayesian model of learning is proposed to capture patients�beliefs on the treatment effect and group assignment. These beliefs are then used to predict patient attrition in clinical trials. Patient learning is demonstrated to be slower when taking into account group ambiguity. In addition, the model corrects for attrition bias in the estimated treatment effect.
Modeling, Control, and Flight Testing of a Small Ducted-Fan Aircraft

Small ducted fan autonomous vehicles have potential for several applications, especially for mi ssions in urban environments. This paper discusses the use of dynamic inversion with neural network adaptation to provide an adaptive controller for the GTSpy, a small ducted fan autonomous vehicle based on the Micro Autonomous Systems’ Helispy. This app roach allows utilization of the entire low speed flight envelope with a relatively poorly understood vehicle. A simulator model is constructed from a force and moment analysis of the vehicle, allowing for a validation of the controller in preparation for flight testing. Data from flight testing of the system is provided. Nomenclature B A A 2 1 ˆ , ˆ , ˆ = linearized vehicle dynamics a
Blind receivers for nonlinearly modulated signals in multipath

Classical blind channel equalization methods may not be suitable for systems with nonlinear modulation (e.g., continuous phase-modulated signals) because the input to the channel may not be i.i.d. due to the modulator's memory. Moreover, the nonlinear characteristics of the modulator further complicate the channel estimation task. In this correspondence, we derive blind maximum likelihood channel estimation algorithms for nonlinearly modulated signals using a hidden Markov model (HMM) formulation. The proposed method implements a stochastic maximum likelihood approach and is well suited for short data records appearing in TDMA systems. Cramer-Rao bounds are derived, and some illustrative simulations are presented.
Alternating Minimization for Mixed Linear Regression

Mixed linear regression involves the recovery of two (or more) unknown vectors from unlabeled linear measurements; that is, where each sample comes from exactly one of the vectors, but we do not know which one. It is a classic problem, and the natural and empirically most popular approach to its solution has been the EM algorithm. As in other settings, this is prone to bad local minima; however, each iteration is very fast (alternating between guessing labels, and solving with those labels). In this paper we provide a new initialization procedure for EM, based on finding the leading two eigenvectors of an appropriate matrix. We then show that with this, a re-sampled version of the EM algorithm provably converges to the correct vectors, under natural assumptions on the sampling distribution, and with nearly optimal (unimprovable) sample complexity. This provides not only the first characterization of EM's performance, but also much lower sample complexity as compared to both standard (randomly initialized) EM, and other methods for this problem.
Duration of action of intravitreal ranibizumab and bevacizumab in exudative AMD eyes based on macular volume measurements

Background/Aims: We use sequential macular volume and central foveal point thickness (CFPT) measurements on optical coherence tomography (OCT) to determine the efficacy and duration of action of ranibizumab vs. bevacizumab in wet age-related macular degeneration (AMD). Methods: Retrospective chart review of patients who received their first treatment of intravitreal ranibizumab or bevacizumab for exudative AMD. We identified 316 patients (202 ranibizumab;114 bevacizumab) who received 823 injections (313 ranibizumab;510 bevacizumab). 74 patients had pre and post-treatment OCTs performed to determine CFPT and macular volume changes. Results: Ranibizumab caused a significant reduction in CFPT (278±84 before treatment vs. 227±80 microns after treatment; p=0.001) and macular volume (7.22±0.96 vs. 6.69±0.74 mm³; p=0.002). Intravitreal bevacizumab caused a similar reduction in CFPT (288±94 vs. 220±55 microns; p=.008) and macular volume (7.36±1.08 vs. 6.50±0.42 mm³; p Conclusions: Both drugs are equally effective at reducing CFPT or macular volume. Bevacizumab appears to take longer to achieve the minimum macular volume and its effects takes longer to wear off, suggesting it can be given less often.
A Visible-Light-Mediated Radical Smiles Rearrangement and its Application to the Synthesis of a Difluoro-Substituted Spirocyclic ORL-1 Antagonist.

A visible-light-mediated radical Smiles rearrangement has been developed to address the challenging synthesis of the gem-difluoro group present in an opioid receptor-like 1 (ORL-1) antagonist that is currently in development for the treatment of depression and/or obesity. This method enables the direct and efficient introduction of the difluoroethanol motif into a range of aryl and heteroaryl systems, representing a new disconnection for the synthesis of this versatile moiety. When applied to the target compound, the photochemical step could be conducted on 15 g scale using industrially relevant [Ru(bpy)3Cl2] catalyst loadings of 0.01 mol %. This transformation is part of an overall five-step route to the antagonist that compares favorably to the current synthetic sequence and demonstrates, in this specific case, a clear strategic benefit of photocatalysis.
Starting Small in an Unfamiliar Environment

Abstract We design a simple model of a developed country buyer’s search for a less developed country supplier and the subsequent relationship between the two parties. Matched firms can ‘start small’ with a trial order to gain information about the ability of the LDC supplier to successfully fill a large order. We show that the propensity for the buyer to start small increases with the cost of search for a new supplier and decreases with the probability that the current or new supplier can fulfill the large order successfully after training. We provide supportive empirical evidence for these and other results.
Hedging Price Volatility Using Fast Transport

Abstract Purchasing goods from distant locations introduces a significant lag between when a product is shipped and when it arrives. These transit lags are trade barriers for firms facing volatile demand, who must place orders before knowing the resolution of demand uncertainty. We provide a model in which airplanes bring producers and consumers together in time. Fast transport allows firms to respond quickly to favorable demand realizations and to limit the risk of unprofitably large quantities during low demand periods. The model predicts that the likelihood and extent to which firms employ air shipments is increasing in the volatility of demand they face, decreasing in the air premium they must pay, and increasing in the contemporaneous realization of demand. We confirm all three conjectures using detailed US import data. Fast transport thus provides firms with a real option to smooth demand volatility on international markets, and we provide simple calculations of that option value. This enables us to identify how the option value relates to goods characteristics, and to changes in air transport premia associated with technological and policy change including the introduction of jet engines, and liberalization of trade in air services.
Infinite Saturated Orders

We generalize the notion of saturated orders to infinite partial orders and give both a set-theoretic and an algebraic characterization of such orders. We then study the proof theoretic strength of the equivalence of these characterizations in the context of reverse mathematics, showing that depending on one’s choice of definitions, this equivalence is either provable in RCA0 or equivalent to ACA0.
Equalization for maximum likelihood detectors

In this paper, the minimum mean-square error (MMSE) technique has been used to equalize the recording channel in order to facilitate the application of the Viterbi detector. The resulting performance has been compared with that of the optimal equalization system which yields the minimum probability of error at the output of the Viterbi detector. The results indicate that depending on the constraint used in the MMSE design, the amount of noise correlation varies significantly at the equalizer output, which in turn makes a large difference in the performance of the Viterbi detector. In particular, in the jitter-dominant channel where unconditioned channel noise samples are highly correlated, the monic constraint on the equalizer target response tends to whiten the noise samples at the equalizer output. This results in a significant performance improvement of the monic constraint upon the fixed-energy constraint as well as the popular partial response targets of the form (1-D)(1+D)/sup n/. >
High-Resolution Photon Counting Using a Lens-Coupled EMCCD Gamma Camera

A lens-coupled electron multiplying charge-coupled device (EMCCD)-based gamma camera capable of performing photon counting for both 99mTc and 125I sources has been constructed. This system differs from previous EMCCD-based gamma cameras by using lens-coupling rather than fiber-optic coupling to transfer the light from the scintillating crystal to the EMCCD. The gamma camera described herein uses a micro-columnar CsI(Tl) crystal, two f/0.95 lenses, and a commercial camera containing the e2v CCD97 EMCCD that was cooled to -70°C. Acquisition of the video-rate frames from the CCD97 was performed using LabVIEW software. Real-time photon counting analysis of the individual scintillation flashes within the CCD97 frames was performed by using the LabVIEW IMAQ software module. An intrinsic resolution of 56 μm FWHM was measured by using a 25 μm slit collimator and 125I source. A single 0.5 mm diameter pinhole collimator was used for SPECT reconstruction of a mouse thyroid gland containing 100 μCi (3.7 MBq) of 125I uptake. We found that although the photopeak for 99mTc (140 keV) could be resolved, the photopeak for 125I (≈ 27 keV) could not be fully resolved due to the low optical transfer efficiency of dual lens coupling (<; 5%). Nonetheless, energy windowing for 125I sources was used to eliminate most of the background events, proving that high-resolution photon counting for low-energy sources can be achieved by using simple lens-coupling.
Enhancing Security Modeling for Web Services Using Delegation and Pass-On

In recent years, security issues in web service environments have been widely studied and various security standards and models have been proposed. However, most of these standards and models focus on individual web services and do not consider the security issues in composite services. In this article, the authors propose an enhanced security model to control the information flow in service chains. It extends the basic web service security models by introducing the concepts of delegation and pass-on. Based on these concepts, new certificates, certificate chains, delegation and pass-on policies, and how they are used to control the information flow are discussed. The authors also introduce a case study from a healthcare information system to illustrate the protocols.
Three-dimensional simulation analysis of the first sections of a standing-wave free-electron laser two-beam accelerator

A 3-D, time-dependent code is used to simulate an array of standing-wave free-electron lasers (SWFELs) in the two-beam accelerator. It is shown that for an array of SWFELs with 9 cavities and a 100.6-ns, 0.5-kA, 7.98-MeV electron beam prebunched at 17.1 GHz, an averaged energy output of 14.7 J/m can be obtained with a fluctuation of less than 11%. >
Design of lipid nanoparticle delivery agents for multivalent display of recombinant Env trimers in HIV vaccination

Background Immunization strategies that elicit antibodies capable of neutralizing diverse strains of the virus will likely be an important part of a successful vaccine against HIV. The envelope trimer is the only neutralizing target on the virus, and strategies to promote durable, high avidity antibody responses against the native intact trimer structure are lacking. We recently developed chemically-crosslinked lipid nanocapsules as carriers of molecular adjuvants and encapsulated or surface-displayed antigens, which promote follicular helper T-cell responses and elicited high-avidity, durable antibody responses to a candidate malaria antigen (Moon et al. Nat. Mater. 10 243 (2011); Moon et al. PNAS 109 1080 (2012)).
Job Access, Commute and Travel Burden among Welfare Recipients

Welfare recipients face a number of obstacles to making the transition from welfare to work including their geographic separation from employment opportunities; many welfare recipients live in "job-poor" neighborhoods far from employment for which they are qualified. Combining administrative data on welfare recipients and employment in Los Angeles with data from the 1990 decennial census, we show that greater access to local jobs in low-wage firms increases the likelihood that welfare recipients find employment in neighborhood jobs. Moreover, welfare recipients who have long commutes earn less than those who find work closer to home, contrary to the pattern for most workers. These findings demonstrate that proximity to low-wage jobs benefits welfare recipients through reduced commuting expenses and increased earnings.
F-theory and the Mordell-Weil group of elliptically-fibered Calabi-Yau threefolds

The Mordell-Weil group of an elliptically fibered Calabi-Yau threefold X contains information about the abelian sector of the six-dimensional theory obtained by compactifying F-theory on X. After examining features of the abelian anomaly coefficient matrix and U(1) charge quantization conditions of general F-theory vacua, we study CalabiYau threefolds with Mordell-Weil rank-one as a first step towards understanding the features of the Mordell-Weil group of threefolds in more detail. In particular, we generate an interesting class of F-theory models with U(1) gauge symmetry that have matter with both charges 1 and 2. The anomaly equations — which relate the Neron-Tate height of a section to intersection numbers between the section and fibral rational curves of the manifold — serve as an important tool in our analysis.
A fast and practical approach to tetrahydropyranylation and depyranylation of alcohols using indium triflate

Abstract Indium triflate-mediated tetrahydropyranylation of alcohols in dichloromethane and depyranylation of these products in aqueous methanol utilizing the same reagent but different molar ratio is described. In addition, indium triflate-promoted conversion of tetrahydropyran ethers to their corresponding acetates has also been described.
Heat and gravitation. II. Stability

Some features of hydro- and thermodynamics, as applied to atmospheres and to stellar structures, are puzzling. 1. The suggestion, first made by Laplace, that our atmosphere has an adiabatic temperature distribution, is confirmed for the lower layers, but the reason why it should be so is difficult to understand. 2. The standard treatment of relativistic thermodynamics does not allow for a systematic treatment of mixtures, such as the mixture of a perfect gas with radiation. 3. The concept of mass in applications of general relativity to stellar structures is less than completely satisfactory. 4. Arguments in which a concept of energy plays a role, in the context of hydro-thermodynamical systems and gravitation, are not always convincing. It was proposed that a formulation of thermodynamics as an action principle may be a suitable approach to adopt for a new investigation of these matters. In this second article of a series we propose to base criteria of stability on the hamiltonian functional that is provided by the variational principle, to replace the reliance that has often been placed on ad hoc definitions of the “energy”. We introduce a new virial principle that is formulated entirely within the Eulerian description of hydrodynamics, which allows a simpler derivation of a well known stability criterion for polytropic stellar configurations. Boundary conditions are based entirely on mass conservation. The new approach is tested on isothermal and polytropic atmospheres and then used to initiate a new study of stars. Traditional results for polytropic, spherical configurations are confirmed, but our study gives new insight and new results for the case that radiation is taken into account.
Can Donors and Non-State Actors Undermine Citizens' Legitimating Beliefs ?

This paper addresses the conditions under which donor and non-state actor service provision is likely to undermine or strengthen citizens' legitimating beliefs. On the one hand, citizens may be less likely to support their government with quasi-voluntary compliance when they credit non-state actors or donors for service provision. On the other hand, the provision of goods and services by donors and non-state actors might strengthen citizens' confidence in their government and their willingness to defer to governmental laws and regulations if citizens believe that the government is essential to leveraging and managing these resources. The author assesses these competing hypotheses using multi-level analyses of Afrobarometer survey data. The sample, drawn from a continuum of developing societies in Africa, allows for analysis of associations between donor and non-state actor service provision and the sense of obligation to comply with the tax authorities, the police and courts. The findings yield support for the hypothesis that the provision of services by donors and non-state actors is strengthening, rather than undermining, the relationship between citizens and the state.
Extracting Concepts' Relations and Users' Preferences for Personalizing Query Disambiguation

For most Web searching applications, queries are commonly ambiguous because words usually contain several meanings. Traditional Word Sense Disambiguation (WSD) methods use statistic models or ontology-based knowledge models to find the most appropriate sense for the ambiguous word. Since queries are usually short, the contexts of the queries may not always provide enough information for disambiguating queries. Thus, more than one interpretation may be found for one ambiguous query. In this paper, we propose a cluster-based WSD method, which finds out all appropriate interpretations for the query. Because some senses of one ambiguous word usually have very close semantic relations, we group those similar senses together for explaining the ambiguous word in one interpretation. If the cluster-based WSD method generates several contradictory interpretations for one ambiguous query, we extract usersâ€™ preferences from clickthrough data, and determine suitable concepts or conceptsâ€™ clusters that meet usersâ€™ interests for explaining the ambiguous query.
Evidence for an Alternative Glycolytic Pathway in Rapidly Proliferating Cells

Proliferating cells, including cancer cells, require altered metabolism to efficiently incorporate nutrients such as glucose into biomass. The M2 isoform of pyruvate kinase (PKM2) promotes the metabolism of glucose by aerobic glycolysis and contributes to anabolic metabolism. Paradoxically, decreased pyruvate kinase enzyme activity accompanies the expression of PKM2 in rapidly dividing cancer cells and tissues. We demonstrate that phosphoenolpyruvate (PEP), the substrate for pyruvate kinase in cells, can act as a phosphate donor in mammalian cells because PEP participates in the phosphorylation of the glycolytic enzyme phosphoglycerate mutase (PGAM1) in PKM2-expressing cells. We used mass spectrometry to show that the phosphate from PEP is transferred to the catalytic histidine (His11) on human PGAM1. This reaction occurred at physiological concentrations of PEP and produced pyruvate in the absence of PKM2 activity. The presence of histidine-phosphorylated PGAM1 correlated with the expression of PKM2 in cancer cell lines and tumor tissues. Thus, decreased pyruvate kinase activity in PKM2-expressing cells allows PEP-dependent histidine phosphorylation of PGAM1 and may provide an alternate glycolytic pathway that decouples adenosine triphosphate production from PEP-mediated phosphotransfer, allowing for the high rate of glycolysis to support the anabolic metabolism observed in many proliferating cells.
Performance and Availability Analysis of a Simple Local Airport Position Domain Monitor for WAAS

: The FAA has investigated the feasibility of a Local Airport Monitor (LAM) using the Wide Area Augmentation System (WAAS) with Local Area Augmentation System (LAAS) avionics for Category I (CAT I) precision approaches. This paper presents a simple LAM concept using position domain monitoring on the ground. A position solution using WAAS corrections with locally measured pseudoranges is compared to the surveyed position of the LAM reference antenna. If this position difference exceeds a threshold for any set of satellites the LAAS avionics might select, WAAS cannot be used for CAT I service. Availability of this LAM concept over CONUS is predicted to be 0.995 for a vertical alert limit (VAL) of 10 m with the optimal 24 GPS constellation. Operation of the method on real WAAS corrections and local pseudorange measurements gives 100 percent availability and no monitor false alarms with a current satellite constellation and a quiet ionosphere.
Structure and function of oxide nanostructures: catalytic consequences of size and composition.

Redox and acid-base properties of dispersed oxide nanostructures change markedly as their local structure and electronic properties vary with domain size. These changes give rise to catalytic behavior, site structures, and reaction chemistries often unavailable on bulk crystalline oxides. Turnover rates for redox and acid catalysis vary as oxide domains evolve from isolated monomers to two-dimensional oligomers, and ultimately into clusters with bulk-like properties. These reactivity changes reflect the ability of oxide domains to accept or redistribute electron density in kinetically-relevant reduction steps, in the formation of temporary acid sites via reductive processes, and in the stabilization of cationic transition states. Reduction steps are favored by low-lying empty orbitals prevalent in larger clusters, which also favor electron delocalization, stable anions, and strong Bronsted acidity. Isomerization of xylenes and alkanes, elimination reactions of alkanols, and oxidation of alkanes to alkenes on V, Mo, Nb, and W oxide domains are used here to demonstrate the remarkable catalytic diversity made available by changes in domain size. The reactive and disordered nature of small catalytic domains introduces significant challenges in their synthesis and their structural and mechanistic characterization, which require in situ probes and detailed kinetic analysis. The local structure and electronic properties of these materials must be probed during catalysis and their catalytic function be related to specific kinetically-relevant steps. Structural uniformity can be imposed on oxide clusters by the use of polyoxometalate clusters with thermodynamically stable and well-defined size and connectivity. These clusters provide the compositional diversity and the structural fidelity required to develop composition-function relations from synergistic use of experiments and theory. In these clusters, the valence and electronegativity of the central atom affects the acid strength of the polyoxometalate clusters and the rate constants for acid catalyzed elementary steps via the specific stabilization of cationic transition states in isomerization and elimination reactions.
Social protection in the face of climate change : targeting principles and financing mechanisms

Climate risk is an important driver of long-term poverty dynamics, especially in rural regions. This paper builds a dynamic, multi-generation household model of consumption, accumulation, and risk management to draw out the full consequences of exposure to climate risk. The model incorporates the long-term impacts of consumption shortfalls, induced by the optimal “asset smoothing” coping behavior of the vulnerable, on the human capital and long-term wellbeing of families. The analysis shows that the long-term level and depth of poverty can be improved by incorporating elements of “vulnerability-targeted social protection” into a conventional system of social protection. The paper also explores the degree to which vulnerability-targeted social protection can be implemented through a subsidized insurance mechanism. The analysis shows that insurance-based vulnerability-targeted social protection dominates (in economic growth and poverty reduction measures) both in-kind transfer mechanisms and vulnerability-targeted protection paid for using a public budget. The relative gains brought about by this scheme of insurance-augmented social protection increase—at least for a while—under climate change scenarios. However, if climate change becomes too severe, then even this novel form of social protection loses its ability to stabilize the extent and depth of poverty.
Producibility in hierarchical self-assembly

Three results are shown on producibility in the hierarchical model of tile self-assembly. It is shown that a simple greedy polynomial-time strategy decides whether an assembly ? is producible. The algorithm can be optimized to use $$O(|\alpha | \log ^2 |\alpha |)$$O(|?|log2|?|) time. Cannon et al. (STACS 2013: proceedings of the thirtieth international symposium on theoretical aspects of computer science. pp 172---184, 2013) showed that the problem of deciding if an assembly ? is the unique producible terminal assembly of a tile system $${\mathcal {T}}$$T can be solved in $$O(|\alpha |^2 |{\mathcal {T}}| + |\alpha | |{\mathcal {T}}|^2)$$O(|?|2|T|+|?||T|2) time for the special case of noncooperative "temperature 1" systems. It is shown that this can be improved to $$O(|\alpha | |{\mathcal {T}}| \log |{\mathcal {T}}|)$$O(|?||T|log|T|) time. Finally, it is shown that if two assemblies are producible, and if they can be overlapped consistently--i.e., if the positions that they share have the same tile type in each assembly--then their union is also producible .
Distribution of the supremum location of stationary processes

The location of the unique supremum of a stationary process on an interval does not need to be uniformly distributed over that interval. We describe all possible distributions of the supremum location for a broad class of such stationary processes. We show that, in the strongly mixing case, this distribution does tend to the uniform in a certain sense as the length of the interval increases to infinity.
Neural integrator: A sandpile model

We investigated a model for the neural integrator based on hysteretic units connected by positive feedback. Hysteresis is assumed to emerge from the intrinsic properties of the cells. We consider the recurrent networks containing either bistable or multistable neurons. We apply our analysis to the oculomotor velocity-to-position neural integrator that calculates eye positions using the inputs that carry information about eye angular velocity. By analyzing this system in the parameter space, we show the following. The direction of hysteresis in the neuronal response may be reversed for the system with recurrent connections compared to the case of unconnected neurons. Thus, for the NMDA receptor-based bistability, the firing rates after ON saccades may be higher than after OFF saccades for the same eye position. The reversal of hysteresis occurs in this model only when the size of hysteresis differs from neuron to neuron. We also relate the macroscopic leak time constant of the integrator to the rate of microscopic spontaneous noise-driven transitions in the hysteretic units. Finally, we investigate the conditions under which the hysteretic integrator may have no threshold for integration.
A Portmanteau Test for Serially Correlated Errors in Fixed Effects Models

We propose a portmanteau test for serial correlation of the error term in a fixed effects model. The test is derived as a Lagrange multiplier test, but it also has a straightforward Wald test interpretation. In Monte Carlo experiments, the test displays good size and power properties.The authors thank the co-editor, the referee, David Drukker, Christian Hansen, and Jeffrey Wooldridge for their helpful comments.
Bending and extension of cross-ply laminates with different moduli in tension and compression

Abstract Composite materials often exhibit different stiffnesses or moduli under tension loading than under compression loading. This behavior is modeled with a bilinear stress-strain curve having a modulus E t in tension and E c in compression as an approximation to the real nonlinear behavior. Under bending loads, laminated composites have both tensile and compressive stresses and hence are not subject to the same behavioral rules as ordinary single modulus materials. The resulting transcendental equilibrium equation is dependent upon the unknown neutral surface. This neutral surface is found and, hence, the equilibrium problem is solved with an iteration technique. The approach is applied to laminates ordinarily thought to be symmetric, antisymmetric, and unsymmetric about the middle surface. All laminates are found to exhibit coupling between bending and extension under bending in contrast to the usual concepts of symmetry and antisymmetry for single modulus laminates. Several approximate approaches are investigated for treating the multimodulus laminate problem. The effect of coupling due to different moduli in tension and compression on stresses and deflections is found to be generally significant for common composite materials such as boron/epoxy and graphitc/epoxy as well as carbon-carbon.
Effects of Alternative Lime Application Rates on Cotton Profitability with Varying Cover Crops, Nitrogen, and Tillage Methods.

Soil acidity and cotton yields are influenced by cover crop, nitrogen, and tillage method. Applying half the recommended lime rate may be possible without reducing cotton yields. Using a nitrogen intensive cover crop and applying less nitrogen should mitigate the effects on soil acidity and yields.
Organohypervalent iodine: development, applications, and future directions.

The synthetic utility of organohypervalent iodine reagents will be illustrated by their use in the α-hydroxydimethylacetal formation reaction from enolizable ketones, α-hydroxylation, α-tosyloxylation, α-alkoxylation and arylation of ketones, carbon−carbon bond formation, and intramolecular cyclopropanation using iodonium ylides. The uses of these reagents in the Hunsdiecker reaction of carboxylic acids and Hofmann rearrangement of carboxamides is presented. Specific transformation in the cubane series are discussed. The syntheses of a wide range of heterocycle structures are also presented. A unifying pathway for virtually all these diverse reactions is offered; the central features being initial attack at the iodonium center, ligand coupling, with reductive elimination of iodobenzene to yield the product.