cssi/SciSciGPT-SciSciNet huggingface dataset:
A Deconstruction Lattice Description of the D1/D5 Brane World-Volume Gauge Theory

I generalize the deconstruction lattice formulation of Endres and Kaplan to two-dimensional super-QCD with eight supercharges, denoted by (4,4), and bifundamental matter. I specialize to a particularly interesting (4,4) gauge theory, with gauge group U(Nc)×U(Nf), and U(Nf) being weakly gauged. It describes the infrared limit of the D1/D5 brane system, which has been studied extensively as an example of the AdS3/CFT2 correspondence. The construction here preserves two supercharges exactly and has a lattice structure quite similar to that which has previously appeared in the deconstruction approach, that is, site, link, and diagonal fields with both the Bose and Fermi statistics. I remark on possible applications of the lattice theory that would test the AdS3/CFT2 correspondence, particularly one that would exploit the recent worldsheet instanton analysis of Chen and Tong.
Phytochemicals in Alzheimer Disease: The Development of Clinical Trials

Polyphenolics and other phytochemicals may have a role in the prevention or treatment of Alzheimer disease. Targets of therapy in Alzheimer disease include neurotransmitter deficits, beta amyloid neurotoxicity, oxidative damage, and inflammation, to name a few. Challenges to the development of phytochemical and other neuroprotectant therapy in Alzheimer disease include the inability to measure pathology in living patients and the challenge of detecting modification of an indolent disease course. These challenges are partially surmounted by the use of animal models and of biomarkers of disease. This review describes currently available animal models and biomarkers and surveys clinical trials of phytochemical therapies that are recently completed or currently under way. Both animal studies and clinical trials of Ginkgo biloba are described, as well as a trial of Uncaria tomentosa that has not been previously reported.
Granular disruption during explosive volcanic eruptions

Volcanic eruptions can inject hazardous ash clouds into the atmosphere. Numerical simulations and experiments on volcanic rock samples show that clasts initially formed deep in the volcanic conduit break-up during collisions in the conduit, thus generating fine-grained clouds of ash.
Why State Constitutions Differ in their Treatment of Same-Sex Marriage

Some states treat a same-sex marriage as legally equivalent to a marriage between a man and a woman. Other states constitutionally prohibit legal recognition of same-sex marriages. In all states that have constitutional restrictions against same-sex marriage, the restrictions were passed by a popular vote. A rationale for allowing citizens to vote on constitutional amendments is to produce constitutional outcomes that reflect variations in attitudes across states. We reexamine the amendment-attitude relationship and find it to be weaker than expected. We then develop an alternate explanation that focuses on procedural variations in how states amend their constitutions. Explicitly integrating key institutional variations into an empirical model with attitudinal data yields an improved explanation of why the constitutions of states with similar public attitudes treat same-sex marriages so differently. Our findings have important implications for people who wish to understand and/or change the future status ...
Do Analysts' Cash Flow Forecasts Mitigate the Accrual Anomaly? International Evidence

ABSTRACT: We investigate the role of analysts' cash flow forecasts in mitigating the accrual anomaly in an international setting. Based on a sample from 20 world market economies, we find less market overestimation of the accrual component of earnings for firms where analysts issue both cash flow forecasts and earnings forecasts, compared with firms where analysts only issue earnings forecasts. Further tests show that analysts' provisions of cash flow forecasts are more likely to be a mechanism that attenuates investors' fixations on earnings in common law countries as opposed to code law countries. This finding is consistent with cash flow predictions by analysts being useful in countries where public disclosures are the primary communication channels in the capital markets. We also find the accrual anomaly to be less severe when analysts provide more accurate cash flow forecasts in common law countries. Our results are robust to additional sensitivity tests, including controlling for potential sample se...
Predicting the present with Bayesian structural time series

This article describes a system for short term forecasting based on an ensemble prediction that averages over different combinations of predictors. The system combines a structural time series model for the target series with a regression component capturing the contributions of contemporaneous search query data. A spike-and-slab prior on the regression coefficients induces sparsity, dramatically reducing the size of the regression problem. Our system averages over potential contributions from a very large set of models and gives easily digested reports of which coefficients are likely to be important. We illustrate with applications to initial claims for unemployment benefits and to retail sales. Although our exposition focuses on using search engine data to forecast economic time series, the underlying statistical methods can be applied to more general short term forecasting with large numbers of contemporaneous predictors.
The Age Specific Incidence Anomaly Suggests that Cancers Originate During Development

The accumulation of genetic alterations causes cancers. Since this accumulation takes time, the incidence of most cancers is thought to increase exponentially with age. However, careful measurements of the age-specific incidence show that the specific incidence for many forms of cancer rises with age to a maximum, and then decreases. This decrease in the age-specific incidence with age is an anomaly. Understanding this anomaly should lead to a better understanding of how tumors develop and grow. Here we derive the shape of the age-specific incidence, showing that it should follow the shape of a Weibull distribution. Measurements indicate that the age-specific incidence for colon cancer does indeed follow a Weibull distribution. This analysis leads to the interpretation that for colon cancer two subpopulations exist in the general population: a susceptible population and an immune population. Colon tumors will only occur in the susceptible population. This analysis is consistent with the developmental orig...
Pipe Insulation Testers

The steady-state temperature distribution of two pipe insulation testers was modeled using the HEATINGS computer code available in the computers at Oak Ridge National Laboratory. One pipe tester, which conformed to the ASTM Test for Thermal Conductivity of Pipe Insulation (C 335-69) specification, had the core heater mounted inside a pipe around which the test insulation was placed. Guard heaters were employed to reduce unwanted axial heat conduction. Computer modeling showed that adjustment of the guard heaters was critical for short testers but not for long ones. A second tester, called an ideal tester, had no guard heaters, and only a simple, resistively heated core heater. The modeling results showed that there is a minimum length-to-thickness (L/S) ratio that will lead to a correct value of thermal conductivity calculated at the midplane ofthe tester. A peripheral heater with backup insulation can be added to the ideal tester to permit selection of the mean temperature of the test insulation. The ideal tester has the advantage over the ASTM design in that no balancing of heater power is required. A mock-up of the ideal tester was constructed and tested with calcium silicate pipe insulation. The core heater was a stainless steel screen, whose low thermal conductivity reduces end losses and permits use of a short tester (∼0.9 m). Measured values on asbestos-free calcium silicate show reasonable agreement with the data of others that contain asbestos.
Detectability of extrasolar planets in radial velocity surveys

Radial velocity surveys are beginning to reach the time baselines required to detect Jupiter analogs, as well as sub-Saturn mass planets in close orbits. Therefore it is important to understand the sensitivity of these surveys at long periods an d low amplitudes. In this paper, I derive analytic expressions for the detectability of plane ts at both short and long periods, for circular and eccentric orbits. In the long period regime, th e scaling of the detection threshold with period depends on the desired detection efficiency. The 99% velocity threshold scales as K / P 2 / a 3 , whereas the 50% velocity threshold scales as K / P / a 3/2 . I suggest an extension of the Lomb-Scargle statistic to Keplerian orbits, and describe how to estimate the false alarm probability associated with a Keplerian fit. I us e this Keplerian periodogram to investigate the effect of eccentricity on detectability. A t short periods, detectability is reduced for eccentric orbits, mainly due to the sparse sampling of th e periastron passage, whereas long period orbits are easier to detect on average if they are eccentric because of the steep velocity gradients near periastron. Fitting Keplerian orb its allows the lost sensitivity at short orbital periods to be recovered for e . 0.6, however there remain significant selection effects against eccentric orbits for e & 0.6, and the small number of highly eccentric planets discovered so far may reflect this. Finally, I present a Bayes ian approach to the periodogram which gives a simple derivation of the probability distribu tions of noise powers, clarifies why the periodogram is an appropriate way to search for long period signals, and emphasises the equivalence of periodogram and least squares techniques.
Credit Risk Derivatives

This article models the pricing of derivatives on credit risk, instruments proposed in 1992 by the International Swap Dealers Association that have started attracting market attention. The exact structure of the instruments continues to evolve today. We develop a framework to understand the key features of this class of products. It is shown that the price of the credit risk option is the expected forward value of a put option on a risky bond with a credit level-adjusted exercise price. Stripping of credit risk from the total risk of the bond is enabled by employing a stochastic strike price for the credit risk option. The article provides a framework for trading and hedging credit risk.
THE FORMATION AND EVOLUTION OF PHYSICIAN TREATMENT STYLES: AN APPLICATION TO CESAREAN SECTIONS

Small-area-variation studies have shown that physician treatment styles differ substantially both between and within markets, controlling for patient characteristics. Using data on the universe of deliveries in Florida and New York over a 15-year period, we examine why treatment styles differ across obstetricians at a point in time and why styles change over time. We find that variation in c-section rates across physicians within a market is about twice as large as variation between markets. Surprisingly, residency programs explain no more than four percent of the variation in physicians' risk-adjusted c-section rates, even among newly trained physicians. Although we find evidence that physicians learn from their peers, they do not substantially revise their prior beliefs regarding treatment due to the local exchange of information. Our results indicate that physicians are not likely to converge over time to a community standard; thus, within-market variation in treatment styles is likely to persist.
Synthesis of ent-ketorfanol via a C-H alkenylation/torquoselective 6π electrocyclization cascade.

The asymmetric synthesis of ent-ketorfanol from simple and commercially available precursors is reported. A RhI-catalyzed intramolecular CH alkenylation/torquoselective 6π electrocyclization cascade provides a fused bicyclic 1,2-dihydropyridine as a key intermediate. Computational studies were performed to understand the high torquoselectivity of the key 6π electrocyclization. The computational results demonstrate that a conformational effect is responsible for the observed selectivity. The ketone functionality and final ring are introduced in a single step by a redox-neutral acid-catalyzed rearrangement of a vicinal diol to give the requisite carbonyl, followed by intramolecular Friedel–Crafts alkylation.
Health and health care for the 21st century: for all the people.

As I reflect on my more than 6 decades of public health service, I am awed at what has been achieved and shocked at what has not. We can prevent and treat diseases formerly considered capricious death sentences. Yet many proven strategies for preventing disease and disability sit on the shelves. The gaping holes in our health care coverage net leave approximately 47 million Americans without coverage.1 Our capability to prevent and treat disease seems to exceed our willingness to apply our interventions. Through most of history, medicine could really cure very little, and the concept of science-driven public health did not exist. By the early 20th century, the so-called medical miracles to prevent and treat disease began to emerge at an increasing pace. Average life spans in the United States increased by nearly 30 years, allowing most people to live into their 80s and some of us substantially longer.2 Services to enable people to spend those additional years free of disability, disease, and pain have not advanced proportionately. Obesity and its associated problems, including diabetes, cardiovascular disease, and orthopedic injury, are largely preventable; unintended pregnancies are too frequent, and many result in abortions that could have been avoided by stronger efforts to guide and assist our young; and we are not adequately prepared for potential influenza pandemics, bioterrorism, or the next global epidemic that, like HIV/AIDS, is unexpected, incurable, and unusual in many aspects of its transmission. As you read this commentary, transplant patients are waiting for organs that could be provided by a better system of distribution; millions of people are crying out because of inadequately treated pain; an aging person is suffering a debilitating hip fracture because no one told her how to get up from a chair; someone will be injured or killed on the highway by the abuser of an addictive drug that will most likely be alcohol; and drug-addicted people seeking help will be told to wait for a treatment slot to open. Four of my own areas of special interest illustrate the promise, peril, and unrealized potential that public health professionals should consider in charting a course for the 21st century.
Proportional response dynamics in the Fisher market

We show that the proportional response dynamics, a utility based distributed dynamics, converges to the market equilibrium in the Fisher market with constant elasticity of substitution (CES) utility functions. By the proportional response dynamics, each buyer allocates his budget proportional to the utility he receives from each good in the previous time period. Unlike the tatonnement process and its variants, the proportional response dynamics is a large step discrete dynamics, and the buyers do not solve any optimization problem at each step. In addition, the goods are always cleared and assigned to the buyers proportional to their bids at each step. Despite its simplicity, the dynamics converges fast for strictly concave CES utility functions, matching the best upper-bound of computing the market equilibrium via the solution of a global convex optimization problem.
Volume Bragg Gratings in PTR glass - New Optical Elements for Laser Design

This is a survey of achievements in semiconductor, solid state and fiber lasers enabled by the use of new optical elements which are volume Bragg gratings recorded in a photo-thermo-refractive (PTR) glass. (Advanced Solid-State Photonics, 2008)
Toward the delineation of therapeutic change principles

Abstract There is a growing discontent among therapists of varying orientations. Psychoanalytic, behavioral, and humanistically oriented clinicians are starting to raise serious questions about the limits of their respective approaches and are becoming more open to contributions from other paradigms. This article documents this trend within the field, which resembles a Kuhnian-type crisis, noting some of the political, economic, and social forces apt to affect our likelihood of ever reaching a consensus within the field and presenting an approach to the delineation and study of commonalities across various orientations.
The political economy of the Essential Air Service program

We find that congressional influences affect the amount of airport subsidies that a congressional district receives through the Essential Air Service (EAS) program. The EAS program was passed with the goal of helping to continue commercial air service to rural communities following deregulation in the 1970s. Using data from 1998–2014, we find strong and consistent evidence that subsidies are higher in districts having congressional representation on the House Transportation and Ways and Means Committees. Our empirical results, when combined with news reports of members claiming credit for securing EAS funding, are consistent with the EAS serving private and public interests.
Prescribing mean curvature: existence and uniqueness problems

The paper presents results on the extent to which mean curvature data can be used to determine a surface in R3 or its shape. The emphasis is on Bonnet’s problem: classify and study the surface immersions in R3 whose shape is not uniquely determined by the first fundamental form and the mean curvature function. These immersions are called Bonnet immersions. A local solution of Bonnet’s problem for umbilic-free immersions follows from papers by Bonnet, Cartan, and Chern. The properties of immersions with umbilics and global rigidity results for closed surfaces are presented in the first part of this paper. The second part of the paper outlines an existence theory for conformal immersions based on Dirac spinors along with its immediate applications to Bonnet’s problem. The presented existence paradigm provides insight into the topology of the moduli space of Bonnet immersions of a closed surface, and reveals a parallel between Bonnet’s problem and Pauli’s exclusion principle.
Syntheses of Biodiesel Precursors: Sulfonic Acid Catalysts for Condensation of Biomass‐Derived Platform Molecules

Synthesis of transportation fuel from lignocellulosic biomass is an attractive solution to the green alternative-energy problem. The production of biodiesel, in particular, involves the process of upgrading biomass-derived small molecules to diesel precursors containing a specific carbon range (C11 -C23). Herein, a carbon-upgrading process utilizing an acid-catalyzed condensation of furanic platform molecules from biomass is described. Various types of sulfonic acid catalysts have been evaluated for this process, including biphasic and solid supported catalysts. A silica-bound alkyl sulfonic acid catalyst has been developed for promoting carbon-carbon bond formation of biomass-derived carbonyl compounds with 2-methylfuran. This hydrophobic solid acid catalyst exhibits activity and selectivity that are comparable to those of a soluble acid catalyst. The catalyst can be readily recovered and recycled, possesses appreciable hydrolytic stability in the presence of water, and retains its acidity over multiple reaction cycles. Application of this catalyst to biomass-derived platform molecules led to the synthesis of a variety of furanic compounds, which are potential biodiesel precursors.
Learning to Love Globalization: Education and Individual Attitudes Toward International Trade

Recent studies of public attitudes toward trade have converged on one central finding: support for trade restrictions is highest among respondents with the lowest levels of education. This has been interpreted as strong support for the Stolper-Samuelson theorem, the classic economic treatment of the income effects of trade that predicts that trade openness benefits those owning factors of production with which their economy is relatively well endowed (those with skills in the advanced economies) while hurting others (low-skilled workers). We reexamine the available survey data, showing that the impact of education on attitudes toward trade is almost identical among respondents in the active labor force and those who are not (even those who are retired). We also find that, while individuals with college-level educations are far more likely to favor trade openness than others, other types of education have no significant effects on attitudes, and some actually reduce the support for trade, even though they clearly contribute to skill acquisition. Combined, these results strongly suggest that the effects of education on individual trade preferences are not primarily a product of distributional concerns linked to job skills. We suggest that exposure to economic ideas and information among college-educated individuals plays a key role in shaping attitudes toward trade and globalization. This is not to say that distributional issues are not important in shaping attitudes toward trade—just that they are not clearly manifest in the simple, broad association between education levels and support for free trade.The authors would like to thank James Alt, Jeffry Frieden, Robert Lawrence, Dani Rodrik, Ron Rogowski, Ken Scheve, Andy Baker, Peter Gourevitch, and Beth Simmons for helpful comments on earlier drafts.
Divergence of Geodesics in Teichmüller Space and the Mapping Class Group

We show that both Teichmuller space (with the Teichmuller metric) and the mapping class group (with a word metric) have geodesic divergence that is intermediate between the linear rate of flat spaces and the exponential rate of hyperbolic spaces. For every two geodesic rays in Teichmuller space, we find that their divergence is at most quadratic. Furthermore, this estimate is shown to be sharp via examples of pairs of rays with exactly quadratic divergence. The same statements are true for geodesic rays in the mapping class group. We explicitly describe efficient paths “near infinity” in both spaces.
A Computer Simulation Laboratory for Social Theories

We present an agent-based model that allows the user to employ different social theories to try to explain and predict social changes. The model is set in the context of an armed insurgency in a developing country. We demonstrate the capabilities of the model by showing how it simulates a news report-based scenario under different theories and combinations of theories.
Serial turbo trellis coded modulation with rate-1 inner code

We develop new, low-complexity turbo codes suitable for bandwidth and power limited systems. These codes are constructed as an extension of repeat-accumulate codes to high-level-modulations. Two design criteria are proposed, based on maximum-likelihood decoding and on Gaussian density evolution in iterative decoding.
Random Walks on Polytopes and an Affine Interior Point Method for Linear Programming

Let K be a polytope in Rn defined by m linear inequalities. We give a new Markov chain algorithm to draw a nearly uniform sample from K. The underlying Markov chain is the first to have a mixing time that is strongly polynomial when started from a “central” point. We use this result to design an affine interior point algorithm that does a single random walk to solve linear programs approximately.
Heidegger’s appropriation of Aristotle: Phronesis, conscience, and seeing through the one:

This article attempts to show that Heidegger’s phenomenology may shed light on political phenomena. It pursues this project by arguing that Heidegger’s phenomenology is an appropriation of Aristotle’s practical philosophy and his conceptualization of phronesis. I argue that, in Being and Time, Heidegger’s ‘circumspection’, which is a capacity for making sense of practical situations, is a translation of phronesis. Heidegger argues, though, that the sight of circumspection is foreshortened by the rules and norms of ‘the one’. In division 2, ‘conscience’ becomes a sharpening of the vision of phronesis, which sees through the one. I then defend Heidegger’s appropriation of phronesis and argue that Heidegger’s concept of conscience, which takes up a critical stance toward plurality, may actually be a proper vision of practical wisdom under modern conditions. I substantiate this claim by turning to an unlikely source to bolster Heidegger’s reading of phronesis and the modern public, Hannah Arendt.
Indium selenide superlattices from (In10Se18)(6-) supertetrahedral clusters

Three-dimensional open framework selenides and tellurides are rare despite the recent progress in the synthesis of indium sulfides with large pore sizes; here we report a family of amine-directed indium selenide superlattices constructed from T3 supertetrahedral (In10Se18)6− clusters.
Large non-Gaussianities in single-field inflation

We compute the three-point correlation function for a general model of inflation driven by a single, minimally coupled scalar field. Our approach is based on the numerical evaluation of both the perturbation equations and the integrals which contribute to the three-point function. Consequently, we can analyse models where the potential has a 'feature', in the vicinity of which the slow roll parameters may take on large, transient values. This introduces both scale and shape dependent non-Gaussianities into the primordial perturbations. As an example of our methodology, we examine the 'step' potentials which have been invoked to improve the fit to the glitch in the for , present in both the one-and three-year WMAP (Wilkinson Microwave Anisotropy Probe) data sets. We show that for the typical parameter values, the non-Gaussianities associated with the step are far larger than those in standard slow roll inflation, and may even be within reach of a next generation cosmic microwave background experiment such as Planck. More generally, we use this example to explain that while adding features to a potential can improve the fit to the two-point function, these are generically associated with a greatly enhanced signal at the three-point level. Moreover, this three-point signal will have a very non-trivial shape and scale dependence, which is correlated with the form of the two-point function, and may thus lead to a consistency check on models of inflation with non-smooth potentials.
Opto-mechanics of the Constellation-X SXT mirrors: challenges in mounting and assembling the mirror segments

The Constellation-X Spectroscopy X-Ray Telescopes consists of segmented glass mirrors with an axial length of 200 mm, a width of up to 400 mm, and a thickness of 0.4 mm. To meet the requirement of < 15 arc-second half-power diameter with the small thickness and relatively large size is a tremendous challenge in opto-mechanics. How shall we limit distortion of the mirrors due to gravity in ground tests, that arises from thermal stress, and that occurs in the process of mounting, affixing and assembling of these mirrors? In this paper, we will describe our current opto-mechanical approach to these problems. We will discuss, in particular, the approach and experiment where the mirrors are mounted vertically by first suspending it at two points.
What causes a Neuron to spike

The computation performed by a neuron can be formulated as a combination of dimensional reduction in stimulus space and the nonlinearity inherent in a spiking output. White noise stimulus and reverse correlation (the spike-triggered average and spike-triggered covariance) are often used in experimental neuroscience to "ask" neurons which dimensions in stimulus space they are sensitive to and to characterize the nonlinearity of the response. In this article, we apply reverse correlation to the simplest model neuron with temporal dynamics--the leaky integrate-and-fire model--and find that for even this simple case, standard techniques do not recover the known neural computation. To overcome this, we develop novel reverse-correlation techniques by selectively analyzing only "isolated" spikes and taking explicit account of the extended silences that precede these isolated spikes. We discuss the implications of our methods to the characterization of neural adaptation. Although these methods are developed in the context of the leaky integrate-and-fire model, our findings are relevant for the analysis of spike trains from real neurons.
Lower bounds on communication loads and optimal placements in torus networks

Fully populated torus-connected networks, where every node has a processor attached, do not scale well since load on edges increases superlinearly with network size under heavy communication, resulting in a degradation in network throughput. In a partially populated network, processors occupy a subset of available nodes and a routing algorithm is specified among the processors placed. Analogous to multistage networks, it is desirable to have the total number of messages being routed through a particular edge in toroidal networks increase at most linearly with the size of the placement. To this end, we consider placements of processors which are described by a given placement algorithm parameterized by k and d: We show formally, that to achieve linear communication load in a d-dimensional k-torus, the number of processors in the placement must be equal to ck/sup d-1/ for some constant c. Our approach also gives a tighter lower bound than existing bounds for the maximum load of a placement for arbitrary number of dimensions for placements with sufficient symmetries. Based on these results, we give optimal placements and corresponding routing algorithms achieving linear communication load in tori with arbitrary number of dimensions.
Can value-added measures of teacher performance be trusted?

AbstractWe investigate whether commonly used value-added estimation strategies produce accurate estimates of teacher effects under a variety of scenarios. We estimate teacher effects in simulated student achievement data sets that mimic plausible types of student grouping and teacher assignment scenarios. We find that no one method accurately captures true teacher effects in all scenarios, and the potential for misclassifying teachers as high- or low-performing can be substantial. A dynamic ordinary least squares estimator is more robust across scenarios than other estimators. Misspecifying dynamic relationships can exacerbate estimation problems.
Passage relevance models for genomics search

We present a passage relevance model for integrating syntactic and semantic evidence of biomedical concepts and topics using a probabilistic graphical model. Component models of topics, concepts, terms, and document are represented as potential functions within a Markov Random Field. The probability of a passage being relevant to a biologist's information need is represented as the joint distribution across all potential functions. Relevance model feedback of top ranked passages is used to improve distributional estimates of query concepts and topics in context, and a dimensional indexing strategy is used for efficient aggregation of concept and term statistics. By integrating multiple sources of evidence including dependencies between topics, concepts, and terms, we seek to improve genomics literature passage retrieval precision. Using this model, we are able to demonstrate statistically significant improvements in retrieval precision using a large genomics literature corpus.
Receiver Spurious Response Measurements

Experimental results are presented which demonstrate that significant intermodulation and cross-modulation products are generated in both the RF amplifier and mixer, in a typical receiver. Measured values of four additional spurious response types are given, for the same receiver. The measurement techniques used represent a departure from traditional methods.
Marginal costs of freeway traffic congestion with on-road pollution exposure externality

The health cost of on-road air pollution exposure is a component of traffic marginal costs that has not previously been assessed. The main objective of this paper is to introduce on-road pollution exposure as an externality of traffic, particularly important during traffic congestion when on-road pollution exposure is highest. Marginal private and external cost equations are developed that include on-road pollution exposure in addition to time, fuel, and pollution emissions components. The marginal external cost of on-road exposure includes terms for the marginal vehicle’s emissions, the increased emissions from all vehicles caused by additional congestion from the marginal vehicle, and the additional exposure duration for all travelers caused by additional congestion from the marginal vehicle. A sensitivity analysis shows that on-road pollution exposure can be a large portion (18%) of marginal social costs of traffic flow near freeway capacity, ranging from 4% to 38% with different exposure parameters. In an optimal pricing scenario, excluding the on-road exposure externality can lead to 6% residual welfare loss because of sub-optimal tolls. While regional pollution generates greater costs in uncongested conditions, on-road exposure comes to dominate health costs on congested freeways because of increased duration and intensity of exposure. The estimated marginal cost and benefit curves indicate a theoretical preference for price controls to address the externality problem. The inclusion of on-road exposure costs reduces the magnitudes of projects required to cover implementation costs for intelligent transportation system (ITS) improvements; the net benefits of road-pricing ITS systems are increased more than the net benefits of ITS traffic flow improvements. When considering distinct vehicle classes, inclusion of on-road exposure costs greatly increases heavy-duty vehicle marginal costs because of their higher emissions rates and greater roadway capacity utilization. Lastly, there are large uncertainties associated with the parameters utilized in the estimation of health outcomes that are a function of travel pollution intensity and duration. More research is needed to develop on-road exposure modeling tools that link repeated short-duration exposure and health outcomes.
Common origin of neutrino mass, dark matter, and baryogenesis

Combining one established idea with two recent ones, it is pointed out for the first time that three of the outstanding problems of particle physics and cosmology, i.e. neutrino mass, dark matter, and baryogenesis, may have a simple common solution, arising from the interactions of a single term, with experimentally verifiable consequences.
Carbon-Fiber-Reinforced Concrete as an Intrinsically Smart Concrete for Damage Assessment during Dynamic Loading

Concrete containing short carbon fibers (0.2–0.5 vol%) wasfound to be an intrinsically smart concrete that can sense elastic and inelastic deformation, as well as fracture. The signal provided is the change in electrical resistance, which is reversible for elastic deformation and irreversible for inelastic deformation and fracture. The presence of electrically conducting short fibers is necessary for the concrete to sense elastic or inelastic deformation, but the sensing of fracture does not require fibers. The fibers serve to bridge the cracks and provide a conduction path. The resistance increase is due to conducting fiber pullout in the elastic regime, conducting fiber breakage in the inelastic regime, and crack propagation at fracture.
Performance analysis of the Rainbow WDM optical network prototype

Rainbow is a prototype optical metropolitan area network (MAN) developed at IBM. It employs wavelength-division multiplexing (WDM) on a fiber-optic, passive-star network topology, with each station equipped with a laser, which is fixed tuned to its own unique wavelength, and a Fabry-Perot filter, which is tunable across all wavelengths. This paper presents a model and analysis of the protocol used in the Rainbow prototype using the equilibrium point analysis (EPA) technique. We examine the system's throughput and how it is affected by various system parameters such as message arrival rate, message length, and timeout duration. We show that, for a given arrival rate, there is a timeout duration that will yield the optimal throughput. The analytical results are verified by simulation.
Wiretap channel with causal state information

A lower bound on the secrecy capacity of the wiretap channel with state information available causally at both the encoder and decoder is established. The lower bound is shown to be strictly larger than that for the noncausal case by Liu and Chen. Achievability is proved using block Markov coding, Shannon strategy, and key generation from common state information. The state sequence available at the end of each block is used to generate a key, which is used to enhance the transmission rate of the confidential message in the following block. An upper bound on the secrecy capacity when the state is available noncausally at the encoder and decoder is established and is shown to coincide with the lower bound for several classes of wiretap channels with state.
Is the chest pain in cardiac syndrome X due to subendocardial ischaemia

Over the past 30 years, the issue of chest pain in patients with a normal coronary angiogram has received much attention.1 The interest in this condition, which has also been termed cardiac syndrome X when the pain is accompanied by ST-segment depression during exercise electrocardiography, has two main reasons: (i) The first is clinical. Does the patient have heart disease? Can the condition be effectively treated? Is the patient's life expectancy shortened? (ii) The second one is relative to the pathophysiology of this condition. Is the chest pain in patients with syndrome X of ischaemic origin? And if the pain is due to myocardial ischaemia what are the mechanisms? Clinically, in a significant proportion of patients with a history of chest pain, the coronary angiogram does not show significant narrowing of the vessel lumen. These patients usually have a poor response to conventional anti-ischaemic therapy, which may lead to the unnecessary performance of repeated coronary angiograms over the years because of recurrence of chest pain. With regard to their prognosis, a number of studies have consistently shown that these patients have a life expectancy similar to that of the general population,2 with the exception of those with conduction abnormalities such as left bundle branch block that may develop dilated cardiomyopathy during follow-up.3 From the pathophysiological point of view things are far from clear. The initial hypothesis that the chest pain is of ischaemic origin was based on the presence of ST-segment depression during spontaneous or stress-induced chest pain, as well as on the evidence of reversible stress-induced myocardial perfusion defects. Furthermore, some studies have provided evidence of reduced endothelium-dependent and independent coronary vasodilatation as well as metabolic evidence of myocardial ischaemia.4 Other studies, however, … Corresponding author. Tel: +44 20 8383 3186; fax: +44 20 8383 3742. E-mail address : paolo.camici{at}csc.mrc.ac.uk
Concerning the absolute stereochemistry of hongconin

Abstract The heretofore unknown absolute stereochemistry of hongconin has been established to be the 1R, 3R isomer via unambiguous chemical synthesis of its enantiomer. The synthetic scheme allows access to appreciable quantities of enantiopure (−)- or (+)-hongconin, analogues, and related diastereomers.
Comparing risk attitudes of organic and non-organic farmers with a Bayesian random coefficient model

Organic farming is usually considered to be more risky than conventional farming, but the risk aversion of organic farmers compared with that of conventional farmers has not been studied. Using a non-structural approach to risk estimation, a Bayesian random coefficient model is used to obtain individual Arrow-Pratt coefficients of absolute risk aversion for a sample of Dutch organic and non-organic arable farmers. The model is estimated using Gibbs sampling. The results indicate that organic farmers are significantly less risk averse than their non-organic colleagues
Effect of the platinum/aluminum sites ratio on the performance of platinum/β zeolite in the reforming of alkylcyclopentanes

Abstract The reforming of methylcyclopentane or ethylcyclopentane over Pt/β zeolite catalysts of various SiO 2 /Al 2 O 3 molar ratios has been examined at various H 2 pressures. The balancing of the Bronsted acidity with the Pt loading at an appropriate pressure maximizes the dehydroisomerization of the naphthenes. A maximum aromatic yield occurs for both naphthenes for a catalyst with a Pt (determined by H 2 chemisorption)/Al atoms ratio of about 3 × 10 −2 (SiO 2 /Al 2 O 3 molar ratio of 130 and a Pt loading of 0.5 wt.-%) and at a pressure of about 800 kPa. The control of the Bronsted acidity via dealumination minimizes coke formation and hydrocracking and results in the preservation of the catalyst activity for many hours-on-stream. The coke was characterized using 1 H-NMR, FTIR, and TGA.
The analysis of tensegrity structures for the design of a morphing wing

Current attempts to build fast, efficient, and maneuverable underwater vehicles have looked to nature for inspiration. However, they have all been based on traditional propulsive techniques, i.e., rotary motors. In the current study a promising and potentially revolutionary approach is taken that overcomes the limitations of these traditional methods-morphing structure concepts with integrated actuation and sensing. Inspiration for this work comes from the manta ray (Manta birostris) and other batoid fish. These creatures are highly maneuverable but are also able to cruise at high speeds over long distances. In this paper, the structural foundation for the biomimetic morphing wing is a tensegrity structure. A preliminary procedure is presented for developing morphing tensegrity structures that include actuating elements. To do this, the virtual work method has been modified to allow for individual actuation of struts and cables. The actuation response of tensegrity beams and plates are studied and results are presented. Specifically, global deflections resulting from actuation of specific elements have been calculated with or without external loads. Finally, a shape optimization analysis of different tensegrity structures to the biological displacement field will be presented.
Indicator Properties of the Paper—Bill Spread: Lessons from Recent Experience

A feature of U.S. postwar business cycle experience that is by now widely documented is the tendency of the spread between the respective interest rates on commercial paper and Treasury bills to widen shortly before the onset of recessions. By contrast, the paper—bill spread did not anticipate the 1990–1991 recession. Empirical work presented in this paper supports two (not mutually exclusive) explanations for this departure from past experience. First, at least part of the paper—bill spread's predictive content with respect to business cycle fluctuations stems from its role as an indicator of monetary policy, but the 1990–1991 recession was unusual in postwar U.S. experience in not being immediately precipitated by tight monetary policy. Second, movements of the spread during the few years just prior to the 1990–1991 recession were strongly influenced by changes in the relative quantities of commercial paper, bank CDs, and Treasury bills that occurred for reasons unrelated to the business cycle. This lat...
Acoustically enhanced boiling heat transfer

An acoustic field is used to increase the critical heat flux (CHF) of a flat-boiling-heat-transfer surface. The increase is a result of the acoustic effects on the vapor bubbles. Experiments are performed to explore the effects of an acoustic field on vapor bubbles in the vicinity of a rigid-heated wall. Work includes the construction of a novel heater used to produce a single vapor bubble of a prescribed size and at a prescribed location on a flat-boiling surface for better study of an individual vapor bubble's reaction to the acoustic field. Work also includes application of the results from the single-bubble heater to a calibrated-copper heater used for quantifying the improvements in CHF.
Testing for linearity of noisy stationary signals

Existing approaches to nonlinear signal detection via testing for linearity of a stationary non-Gaussian time series may fail if the data are contaminated with noise. These tests are based upon the skewness function (or bicoherence) of the time series which is a constant for linear processes in the absence of any measurement noise. In this paper a modification to the Subba Rao and Gabr (1980) approach is proposed by defining a scaled skewness function based upon the data bispectrum and a bispectrum-based power spectrum estimate. Under the null hypothesis, the modified skewness function of the noisy data is a constant. It is shown that this modified skewness function satisfies all the desired properties to qualify as a test statistic for the Subba Rao and Gabr test. On the other hand modifications to the Hinich (1982) test are not obvious. Computer simulation results are presented in support of the proposed approach. >
Optimal Taxation of Wealthy Individuals

This paper studies the determinants of optimal taxes for wealthy individuals faced with capital income risk. I develop a model of optimal taxation of capital income in which wealth and income inequality is a result of capital income shocks together with frictions in financial markets. I use the model to study optimal taxation of various types of capital income: capital income from controlled businesses, outside the business as well as bequests. In presence of risk-return trade-offs, i.e., when more productive investments are riskier, I show that it is typically optimal to have progressive saving taxes. Furthermore, in an intergenerational context, I show that bequest taxes should be negative. Finally, I study the implications of the model on long run efficient distribution of wealth. I show that the long-run distribution of wealth has a fat-tail distribution and compare the efficient tail of the wealth distribution to the one resulting from an ad-hoc incomplete market model.
The Moderating Effects of Task Complexity and Task Attractiveness on the Impact of Monetary Incentives in Repeated Tasks

ABSTRACT: This study examines the interactive effects of task complexity and attractiveness on the effectiveness of explicit monetary incentives in promoting task performance. We provide theory for and find an interaction such that monetary incentives are more effective when tasks are less complex, but only when the task is viewed as relatively unattractive. In addition, by varying task complexity, this study extends Bailey et al. (1998), finding that when incentive pay leads to higher performance, it is through faster initial performance, not faster improvement.
A restricted maximum likelihood estimator for truncated height samples.

Abstract A restricted maximum likelihood (ML) estimator is presented and evaluated for use with truncated height samples. In the common situation of a small sample truncated at a point not far below the mean, the ordinary ML estimator suffers from high sampling variability. The restricted estimator imposes an a priori value on the standard deviation and freely estimates the mean, exploiting the known empirical stability of the former to obtain less variable estimates of the latter. Simulation results validate the conjecture that restricted ML behaves like restricted ordinary least squares (OLS), whose properties are well established on theoretical grounds. Both estimators display smaller sampling variability when constrained, whether the restrictions are correct or not. The bias induced by incorrect restrictions sets up a decision problem involving a bias–precision tradeoff, which can be evaluated using the mean squared error (MSE) criterion. Simulated MSEs suggest that restricted ML estimation offers important advantages when samples are small and truncation points are high, so long as the true standard deviation is within roughly 0.5 cm of the chosen value.