cssi/SciSciGPT-SciSciNet huggingface dataset:
A New Regularization of Coulomb Friction

We present a new regularization of Coulomb's law of friction that permits a straightforward incorporation of frictional forces within existing numerical simulations. Similar to existing regularizations, the proposed modification to Coulomb friction leads to a continuous representation of friction and does not require the identification of transitions between slip and stick. However, unlike more common regularizations, the current reformulation maintains a structure at zero contact velocity that is identical to the classical, discontinuous form of Coulomb friction. The implementation of this regularization is presented through two examples in which slip-stick motion induced by sliding friction is of primary importance. The first is a simple one degree-of-freedom system and illustrates the existence of nontrivial equilibrium states. The second example is a multi-degree-of-freedom system in which the present model provides a computationally efficient scheme for simulating the dissipation arising from sliding friction. For systems in which slip-stick transitions are important the proposed regularization provides a computationally efficient scheme to obtain time-accurate simulations.
Measuring misinformation in repeat trial pick 1 of 2 tests.

An extension is described to a product testing model to account for misinformation among subjects. A misinformed subject is one who associates the taste of product A with product B and vice-versa; thus, the subject would tend to perform incorrectly on pick 1 of 2 tests. A likelihood ratio test for the presence of misinformation is described. The model is applied to a data set, and misinformation is found to exist. Biases due to model misspecificationand other implications for product testing are discussed.
Long-range order in a quasi one-dimensional non-equilibrium three-state lattice gas

Biased diffusion of two species with conserved dynamics on a 2 × L periodic lattice is studied via Monte Carlo simulations. In contrast to its simple one-dimensional version on a ring, this quasi one-dimensional model surprisingly exhibits phase separation in its steady state, which is characterized by one macroscopic particle cluster. We study the order parameter and the cluster-size distributions as a function of the system size L, to support the above picture.
Patterns of Trade and Oligopoly Equilibria: An Example

This paper investigates, via an example, the effects of oligopolistic competition in a two-country two-good “Ricardian” model of international trade. By contrast with results that apply to the competitive free-trade equilibrium, at the oligopoly equilibrium industries with different technologies can profitably survive. Moreover, it is shown that, in an oligopolistic setting, the pattern of trade cannot be inferred either by pre-trade prices or by the comparative advantage principle.
Photonic Devices for Next-Generation Broadband Fiber Access Networks

ABSTRACT Next-generation optical access networks w ill deliver substantial benefits to consumers including a dedicated high-QoS access to bit rates of hundreds of Megabits per second. They must include the follo wing features such as: reduced total cost of ownership, higher reliability, lower energy consumpti on, better flexibility and efficiency. This paper will describe recent progress and technol ogy toward that goal usin g novel phot onic devices Keywords: Fiber access network, PON, MEMS, sleep mode. 1. INTRODUCTION To meet the ever-increasing bandwidth demands of broadband access, optical networks are considered to be the best longterm solution for last mile, especially when future bandwidth-demanding services such as triple play are provided. Currently gigabit-rate passive optical networks (PONs) such as EPON or GPON are widely deployed. Current PONs have acquired huge volume of residential and business customers, and their deployments are growing rapidly worldwide. However as network demands keep growing, it is becoming increasingly clear that current PON systems have serious problems including insufficient bandwidth, security issues and inefficient energy consumption[1][2]. In order to solve these issues, new architecture and technolo gies which can gracefully evolve over the existing infrastructure would be necessary. The first part of this article reviews the cu rrent challenges of broadband fiber access network. The second part of this article will show the possible solutions to mitigate such challenges. Moreover the solutions add more intelligence and more powerful functions into PONs system while still providing energy-cost efficiency.
A 3D neurovascular bundles segmentation method based on MR-TRUS deformable registration

In this paper, we propose a 3D neurovascular bundles (NVB) segmentation method for ultrasound (US) image by integrating MR and transrectal ultrasound (TRUS) images through MR-TRUS deformable registration. First, 3D NVB was contoured by a physician in MR images, and the 3D MRdefined NVB was then transformed into US images using a MR-TRUS registration method, which models the prostate tissue as an elastic material, and jointly estimates the boundary deformation and the volumetric deformations under the elastic constraint. This technique was validated with a clinical study of 6 patients undergoing radiation therapy (RT) treatment for prostate cancer. The accuracy of our approach was assessed through the locations of landmarks, as well as previous ultrasound Doppler images of patients. MR-TRUS registration was successfully performed for all patients. The mean displacement of the landmarks between the post-registration MR and TRUS images was less than 2 mm, and the average NVB volume Dice Overlap Coefficient was over 89%. This NVB segmentation technique could be a useful tool as we try to spare the NVB in prostate RT, monitor NVB response to RT, and potentially improve post-RT potency outcomes.
Discretization of a vortex sheet, with an example of roll-up☆

Abstract The point vortex approximation of a vortex sheet in two space dimensions is examined and a remedy for some of its shortcomings is suggested. The approximation is then applied to the study of the roll-up of a vortex sheet induced by an elliptically loaded wing.
Toward an enantioselective total synthesis of sarain A: construction of an advanced intermediate and rearrangement of the sarain A core under mild conditions.

A high-yielding N-sulfonyliminium ion−enoxysilane cyclization and a ring-closing metathesis are key steps in the enantioselective synthesis of late-stage intermediates en route to sarain A. Also revealed is an unprecedented rearrangement of the tetracyclic sarain A core under mildly acidic conditions.
A Radio Survey of Type Ib and Ic Supernovae: Searching for Engine-driven Supernovae

The association of ?-ray bursts (GRBs) and core-collapse supernovae (SNe) of Type Ib and Ic was motivated by the detection of SN 1998bw in the error box of GRB 980425 and the now secure identification of SN 2003dh in the cosmological GRB 030329. The bright radio emission from SN 1998bw indicated that it possessed some of the unique attributes expected of GRBs, namely, a large reservoir of energy in (mildly) relativistic ejecta and variable energy input. The two popular scenarios for the origin of SN 1998bw are a typical cosmological burst observed off-axis or a member of a new distinct class of supernova explosions. In the former, about 0.5% of local Type Ib/c SNe are expected to be similar to SN 1998bw; for the latter no such constraint exists. Motivated thus, we began a systematic program of radio observations of most reported Type Ib/c SNe accessible to the Very Large Array. Of the 33 SNe observed from late 1999 to the end of 2002, at most one is as bright as SN 1998bw. From this we conclude that the incidence of such events is 3%. Furthermore, analysis of the radio emission indicates that none of the observed SNe exhibit clear engine signatures. Finally, a comparison of the SN radio emission to that of GRB afterglows indicates that none of the SNe could have resulted from a typical GRB, independent of the initial jet orientation. Thus, while the nature of SN 1998bw remains an open question, there appears to be a clear dichotomy between the majority of hydrodynamic and engine-driven explosions.
Insurance and Community Welfare

Abstract Federal relief and insurance programs for households living in areas subject to natural disasters have evolved in the absence of private insurance. Conventional wisdom suggests that these programs serve only to subsidize those choosing to live in hazardous areas at the expense of the taxpaying public. The results presented in this paper suggest otherwise. In a simple model of housing markets, where locations are differentiated by both distance to a centrally located business district and risk of loss due to natural disasters, providing insurance to those in hazardous areas confers nonpecuniary benefits to households residing in risk-free areas within the same community. Insurance affects the long-run development of a community by increasing development in hazardous areas, allowing households to consume spatial amenities at a lower cost than if there were no insurance. Similar results obtain with regard to subsidized insurance for households at risk.
Unexpected loss of the β-lactam ring during rearrangement of a penicillin sulfoxide

Abstract N-carbobenzyloxy 6-amino penicillanate sulfoxide gave a thiazole on refluxing with trimethyl phosphite (TMP) instead of the expected thiazoline-azetidinone derivative.
Universal three-body physics at finite energy near Feshbach resonances

We find that universal three-body physics extends beyond the threshold regime to non-zero energies. For ultracold atomic gases with a negative two-body s-wave scattering length near a Feshbach resonance, we show that the resonant peaks characteristic of Efimov physics persist in three-body recombination to higher collision energies. For this and other inelastic processes, we use the adiabatic hyperspherical representation to derive universal analytical expressions for their dependence on the scattering length, the collision energy and—for narrow resonances—the effective range. These expressions are supported by full numerical solutions of the Schrodinger equation and display log-periodic dependence on energy characteristic of Efimov physics. This dependence is robust and might be used to experimentally observe several Efimov features.
Intravenous fluorescein interference with clinical laboratory tests.

The results of laboratory tests performed after fluorescein angiography may be erroneous because of interference by intravenous fluorescein. We investigated this potential interference in four adults at intervals of five minutes, three hours, six hours, and 12 hours after fluorescein injection. We used a panel of serum and urine chemistry tests on seven commonly used instruments. A significant change in the reported concentration of a serum or urine analyte was defined as a result beyond ±3 coefficients of variation of the preinjection baseline value for the test on a specific instrument. The determinations of creatinine, total protein, cortisol, digoxin, quinidine, and thyroxine in serum were affected by intravenous fluorescein. The urine tests were unaltered. The physician must be aware of the problem of interpreting clinical chemistry results after fluorescein angiography.
Transient Events from Neutron Star Mergers

Mergers of neutron stars (NS + NS) or neutron stars and stellar-mass black holes (NS + BH) eject a small fraction of matter with a subrelativistic velocity. Upon rapid decompression, nuclear-density medium condenses into neutron-rich nuclei, most of them radioactive. Radioactivity provides a long-term heat source for the expanding envelope. A brief transient has a peak luminosity in the supernova range, and the bulk of radiation in the UV-optical domain. We present a very crude model of the phenomenon, and simple analytical formulae that can be used to estimate the parameters of a transient as a function of poorly known input parameters. The mergers may be detected with high-redshift supernova searches as rapid transients, many of them far away from the parent galaxies. It is possible that the mysterious optical transients detected by Schmidt et al. are related to neutron star mergers, since they typically have no visible host galaxy.
Preventing False Discovery in Interactive Data Analysis Is Hard

We show that, under a standard hardness assumption, there is no computationally efficient algorithm that given n samples from an unknown distribution can give valid answers to n3+o(1) adaptively chosen statistical queries. A statistical query asks for the expectation of a predicate over the underlying distribution, and an answer to a statistical query is valid if it is "close" to the correct expectation over the distribution. Our result stands in stark contrast to the well known fact that exponentially many statistical queries can be answered validly and efficiently if the queries are chosen non-adaptively (no query may depend on the answers to previous queries). Moreover, Dwork et al. [1], showed how to accurately answer exponentially many adaptively chosen statistical queries via a computationally inefficient algorithm. They also gave efficient algorithm that can answer nearly n2 adaptively chosen queries, which shows our result is almost quantitatively tight. Conceptually, our result demonstrates that achieving statistical validity alone can be a source of computational intractability in adaptive settings. For example, in the modern large collaborative research environment, data analysts typically choose a particular approach based on previous findings. False discovery occurs if a research finding is supported by the data but not by the underlying distribution. While the study of preventing false discovery in Statistics is decades old, to the best of our knowledge our result is the first to demonstrate a computational barrier. In particular, our result suggests that the perceived difficulty of preventing false discovery in today's collaborative research environment may be inherent.
Absorption band Q model for the Earth

Body wave, surface wave, and normal mode data are used to place constraints on the frequency dependence of Q in the mantle. With a simple absorption band model it is possible to satisfy the shear sensitive data over a broad frequency range. The quality factor Qs (ω) is proportional to ωα in the band and to ω and ω−1 at higher and lower frequencies, respectively, as appropriate for a relaxation mechanism with a spectrum of relaxation times. The parameters of the band are Q(min) = 80, α = 0.15, and width, 5 decades. The center of the band varies from 101 seconds in the upper mantle, to 1.6×103 seconds in the lower mantle. The shift of the band with depth is consistent with the expected effects of temperature, pressure and stress. High Qs regions of the mantle are attributed to a shift of the absorption band to longer periods. To satisfy the gravest fundamental spheroidal modes and the ScS data, the absorption band must shift back into the short-period seismic band at the base of the mantle. This may be due to a high temperature gradient or high shear stresses. A preliminary attempt is also made to specify bulk dissipation in the mantle and core. Specific features of the absorption band model are low Q in the body wave band at both the top and the base of the mantle, low Q for long-period body waves in the outer core, an inner core Qs that increases with period, and low QP/QS at short periods in the middle mantle. The short-period Qs increases rapidly at 400 km and is relatively constant from this depth to 2400 km. The deformational Q of the earth at a period of 14 months is predicted to be 463.
A Characterization Theorem for Aumann Integrals

A Daniell-Stone type characterization theorem for Aumann integrals of set-valued measurable functions will be proven. It is assumed that the values of these functions are closed convex upper sets, a structure that has been used in some recent developments in set-valued variational analysis and set optimization. It is shown that the Aumann integral of such a function is also a closed convex upper set. The main theorem characterizes the conditions under which a functional that maps from a certain collection of measurable set-valued functions into the set of all closed convex upper sets can be written as the Aumann integral with respect to some σ-finite measure. These conditions include the analog of the conlinearity and monotone convergence properties of the classical Daniell-Stone theorem for the Lebesgue integral, and three geometric properties that are peculiar to the set-valued case as they are redundant in the one-dimensional setting.
Constraints on the Value of the Fine Structure Constant from Gravitational Thermodynamics

In this paper I show how the second law of thermodynamics, generalized to include event horizon area, places interesting constraints on the value of the fine structure constant α. A simple analysis leads to the approximate constraint α<1, although I suggest ways in which this bound might be reduced by a more detailed calculation. The analysis also leads to the conclusion that the existence of classical Dirac and point-like magnetic monopoles are inconsistent with the second law, and that GUT monopoles are inconsistent with either the second law or the existence of minicharged particles.
Field dependence and lateralization of verbal and configurational processing.

Summary With tachistoscopic presentation, relatively field-independent 18- to 30-year-old males were found to show a significant right-visual-field advantage in reaction-time in a letter discrimination task, while relatively field-dependent subjects did not show a significant hemifield difference. In a second study, relatively fieldindependent 18- to 30-year-old males again showed a significant right-visual-field superiority in reaction time to letter discrimination, and in addition showed a significant left-visual-field superiority in tachistoscopic face discrimination, while relatively field-dependent subjects showed no significant hemifield difference on either task. The results are interpreted as indicating a link between Witkin's concept of psychological differentiation and differentiation at the neural level, as manifested by specialization of function of the cerebral hemispheres.
Generalized Jones traces and Kazhdan–Lusztig bases

Abstract We develop some applications of certain algebraic and combinatorial conditions on the elements of Coxeter groups, such as elementary proofs of the positivity of certain structure constants for the associated Kazhdan–Lusztig basis. We also explore some consequences of the existence of a Jones-type trace on the Hecke algebra of a Coxeter group, such as simple procedures for computing leading terms of certain Kazhdan–Lusztig polynomials.
Anisotropy in the Cosmic Microwave Background at Degree Angular Scales: Python V Results

Observations of the microwave sky using the Python telescope in its fifth season of operation at the Amundsen-Scott South Pole Station in Antarctica are presented. The system consists of a 0.75 m off-axis telescope instrumented with a HEMT amplifier-based radiometer having continuum sensitivity from 37 to 45 GHz in two frequency bands. With a 091 × 102 beam, the instrument fully sampled 598 deg2 of sky, including fields measured during the previous four seasons of Python observations. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background, we place constraints on the angular power spectrum of fluctuations in eight multipole bands up to l ~ 260. The observed spectrum is consistent with both the COBE experiment and previous Python results. There is no significant contamination from known foregrounds. The results show a discernible rise in the angular power spectrum from large (l ~ 40) to small (l ~ 200) angular scales. The shape of the observed power spectrum is not a simple linear rise, but has a sharply increasing slope starting at l ~ 150.
Fracture toughness characterization of several aluminum alloys in semi-brittle fracture

Abstract A method has recently been developed for determining a nonlinear fracture toughness parameter defined by the relation G c = C G c where Gc is the critical elastic strain energy rate as defined by Irwin. The C term is a function of the nonlinearity of the load-displacement test record and has been evaluated using the three parameter Ramberg-Osgood approach, although other curve fitting techniques could be applied as well. The method is quite straightforward and is applicable to plane stress, plane strain and mixed mode testing although only plane stress conditions are considered in this paper. For the case of a linear load-displacement record C → 1 and G c reduces to the linear elastic result. The toughness parameter G c has been evaluated for a number of high strength aluminum alloys and compared with published Gc values for these materials. The tests were conducted on center-cracked sheets of 2014-T6, 2024-T81, 7075-T6 and 7475-T61 aluminum alloys under conditions of varying specimen geometry and displacement gage length. It was found that the values of G c obtained from displacement readings with a gage length of 2 in. generally agreed with published values of G c = K c 2 E . The G c values were found to vary inversely with gage length and a/w ratios. The variation in values for G c is of the same order of magnitude as the scatter in published values for Gc. However, G c appears to be less sensitive than Gc to changes in a/w.
A microwave-enhanced, solventless Mannich condensation of terminal alkynes and secondary amines with para-formaldehyde on cuprous iodide doped alumina

A microwave-enhanced, solventless Mannich condensation of terminal alkynes and secondary amines with para-formaldehyde on cuprous iodide doped alumina has been developed. β-Aminoalkynes are generated in good yields. The reaction can be extended to include a cyclization, which affords 2-substituted benzo[b]furans. The chemoselectivity of the reaction indicates that terminal alkynes are much more reactive than enolizable ketones under the reaction conditions.
Domestic violence intervention program: Unconditional shelter?

This case examines the difficult choices facing a domestic violence shelter in crisis. Beth George had been on the run from her estranged husband with her two sons for three years. When the shelter hired Beth rather than another former resident (her roommate at the shelter) for a staff position, the roommate called Beth's ex-husband and told him where they were. Police arrested Beth, sent the children back to their father, and began an investigation of whether shelter staff had knowingly harbored a fugitive. The shelter had just begun a fundraising campaign for a new building, but all financial contributions immediately stopped, throwing the organization into financial crisis. The executive director and staff were under enormous pressure and faced possible criminal sentences. The board had to try to minimize the damage to its reputation in the media, figure out how to keep the organization from failing financially, decide whether to continue to employ Beth George and the executive director, who were under criminal investigation, and fend off attacks from fathers' rights activists. The case explores the difficult management issues facing an organization and individuals in crisis. It examines how class, sexual orientation, race, and feminist ideology structure services to battered women. It also provides a window into the difficult job of front-line workers skating on the edge of the law as the law begins to recognize and protect victims of intimate violence. It invites readers to consider how one should decide what and whom to believe. Finally, it considers the significance of grass-roots feminist mobilizing to support feminist organizations.
Estimating the Effect of the Age Distribution on Cyclical Output Volatility Across the United States

Abstract I exploit the variation in demographic change across the United States to estimate the relationship between the age distribution in the population and the magnitude of cyclical output volatility. According to panel regression estimates, the relative supply of young workers, or youth share, has a statistically significant effect on the volatility of state-by-state GDP. Moreover, changes to the age distribution can account for up to 58% of the recent reduction in business cycle fluctuations, indicating a critical link between the youth share and output volatility.
Percutaneous Management of a Bladder-Drained Pancreas Transplant Pseudocyst by a Transcystic Approach

Background We describe a 35-year-old male type 1 diabetic who underwent a cadaveric combined kidney-bladder-drained pancreas transplant with a duodenocystostomy for exocrine drainage who developed a large pelvic pseudocyst associated with a dilated pancreatic duct and an elevated serum amylase level. Methods Due to the risk of surgical revision and the possibility of creating a cutaneous fistula with conventional percutaneous drainage, a pseudocyst-to-bladder drainage was performed. After the procedure, the catheter was capped to allow drainage of the pancreatic secretions into the bladder. Results After drainage, the patient's serum amylase and lipase normalized along with resolution of the pseudocyst. The tube was removed after 19 weeks with no evidence of a recurrent pseudocyst and a normal serum amylase level. Conclusion The percutaneous pseudocyst-cystostomy obviated the need for surgical revision of the exocrine gland drainage and thus eliminated the morbidity and the potential risk of graft loss associated with such surgery.
Unidirectional loop network layout by a LP heuristic and design of telecommunications networks

In this paper, we present a new linear programming-based heuristic procedure for optimal design of the unidirectional loop network layout problem. The heuristic procedure employs a linear programming formulation and solves the problem using the flow matrix of the unidirectional loop problem. To find an optimal solution, one can either generate all possible solutions or use a branch-and-bound procedure. But, both above methods require very high computational time and computer memory for larger problems. The heuristic developed in this paper is quite fast and obtains near optimal solutions. The heuristic procedure was tested on 16 different problems selected from the literature. The results showed that in most cases optimal—and in a few cases near optimal—solutions were obtained with very little computational time. Several examples are discussed. We also demonstrate that the above problem formulation and approach can be used to solve a special class of telecommunication networks where a set of computers (or processors) are attached by unidirectional point-to-point links around a loop.
Organoiridium complexes as models for homogeneously catalyzed reactions

Cas des additions oxydantes (d'hydrogene, d'halogenure d'alkyl, activation des liaisons C-H), d'eliminations reductrices, des carbonylations, des eliminations en β, des oligomerisations...
Design of controllers for linear parameter-varying systems by the gain scheduling technique

Abstract Design of controllers for linear multi-input multi-output systems whose dynamics depend on a time-varying parameter is studied. Design algorithms for the state feedback control law based on the gain scheduling technique are proposed. State feedback control laws are designed so that one of the following goals is achieved: (i) the poles of the closed-loop system for all fixed parameter values are placed in a small neighborhood of a set of desired closed-loop poles; (ii) the stability of the closed-loop system for all fixed parameter values guarantees that the of the system (with the time-varying parameter), independent of the rate of change of the parameter. Rigorously justified and computationally appealing design algorithms are developed.
Hydrogen storage properties of the Mg–Ti–H system prepared by high-energy–high-pressure reactive milling

Abstract Magnesium-based alloys are among the promising materials for hydrogen storage and fuel cell applications due to their high hydrogen content. In the present work, we investigated the hydrogen release/uptake properties of the Mg–Ti–H system. Samples were prepared from the mixtures of MgH 2 and TiH 2 in molar ratios of 7:1 and 4:1 using a high-energy-high-pressure (HEHP) mechanical ball-milling method under 13.8 MPa hydrogen pressure. Thermogravimetric analysis (TGA) showed that a relatively large amount of hydrogen (5.91 and 4.82 wt.%, respectively, for the above two samples) was released between 126 and 313 °C while temperature was increased at a heating rate of 5 °C min −1 under an argon flow. The onset dehydrogenation temperature of these mixtures, which is 126 °C, is much lower than that of MgH 2 alone, which is 381 °C. The activation energy of dehydrogenation was 71 kJ mol −1 , which is much smaller than that of as-received MgH 2 (153 kJ mol −1 ) or as-milled MgH 2 (96 kJ mol −1 ). Furthermore, the hydrogen capacity and the dehydrogenation temperature remained largely unchanged over five dehydrogenation and rehydrogenation cycles.
Multiuser diversity gain in cognitive networks

Dynamic allocation of resources to the best link in large multiuser networks offers considerable improvement in spectral efficiency. This gain, often referred to as multiuser diversity gain, can be cast as double-logarithmic growth of the network throughput with the number of users. In this paper, we consider large cognitive networks granted concurrent spectrum access with license-holding users. The primary network affords to share its underutilized spectrum bands with the secondary users. We assess the optimal multiuser diversity gain in the cognitive networks by quantifying how the sum-rate throughput of the network scales with the number of secondary users. For this purpose, we look at the optimal pairing of spectrum bands and secondary users, which is supervised by a central entity fully aware of the instantaneous channel conditions, and show that the throughput of the cognitive network scales double-logarithmically with the number of secondary users (N) and linearly with the number of available spectrum bands (M), i.e., M log log N. We then propose a distributed spectrum allocation scheme, which does not necessitate a central controller or any information exchange among different secondary users and still obeys the optimal throughput scaling law. This scheme requires that some secondary transmitter-receiver pairs exchange log M information bits among themselves. We also show that the aggregate amount of information exchange between secondary transmitter-receiver pairs is asymptotically equal to M log M. Finally, we show that our distributed scheme guarantees fairness among the secondary users, meaning that they are equally likely to get access to an available spectrum band.
Using costs in cost-effectiveness models for chronic diseases: lessons from diabetes.

Background: Cost-effectiveness models for chronic diseases frequently require simulating the development of disease complications over a long period. Model development often focuses on disease progression, with less attention devoted to costs. Objective: To identify key challenges in incorporating costs in cost-effectiveness models for chronic diseases. Research Design: We use our experience in developing and applying a diabetes cost-effectiveness model to illustrate the challenges in incorporating costs in cost-effectiveness models for chronic diseases. Results: Costs used in cost-effectiveness analyses for chronic diseases are sometimes drawn from a variety of published sources with little concern about consistency between sources or the underlying functional form for costs. Identifying costs of complications in chronic disease modeling often receives inadequate attention compared to the time and effort devoted to modeling disease progression. Costs of averted complications typically cannot be estimated during a trial, because these complications begin to accrue years after the intervention. Complication costs may be estimated through gross-costing, using an additive cost function with individual complication costs derived from difference sources, or through cost regressions that apply a multiplicative functional form using a single data source. The choice between additive and multiplicative cost functions may affect the cost-effectiveness ratios generated by the model. Current guidelines do not provide much guidance on choosing between the costing approaches. Conclusions: Developing a set of standard cost estimates might streamline the modeling process for chronic diseases, but standardization will require careful attention to functional form and the selection of appropriate data sets.
Combinatorial and Algebraic Structure in Orlik-Solomon Algebras

The Orlik?Solomon algebra A(G) of a matroid G is the free exterior algebra on the points, modulo the ideal generated by the circuit boundaries. On one hand, this algebra is a homotopy invariant of the complement of any complex hyperplane arrangement realizing G. On the other hand, some features of the matroid G are reflected in the algebraic structure of A(G). In this mostly expository article, we describe recent developments in the construction of algebraic invariants of A(G). We develop a categorical framework for the statement and proof of recently discovered isomorphism theorems which suggests a possible setting for classification theorems. Several specific open problems are formulated.
Corotational instability of inertial‐acoustic modes in black hole accretion discs: non‐barotropic flows

We study the effect of corotation resonance on the inertial-acoustic oscillations (p-modes) of black hole accretion discs. Previous works have shown that for barotropic flows (where the pressure depends only on the density), wave absorption at the corotation resonance can lead to mode growth when the disc vortensity, ζ = κ 2 /(2ΩΣ) (where Ω, κ, Σ are the rotation rate, radial epicyclic frequency and surface density of the disc, respectively), has a positive gradient at the corotation radius. Here, we generalize the analysis of the corotation resonance effect to non-barotropic fluids. We show that the mode instability criterion is modified by the finite radial Brunt―Vaisala frequency of the disc. We derive an analytic expression for the reflectivity when a density wave impinges upon the corotation barrier, and calculate the frequencies and growth rates of global p-modes for disc models with various α-viscosity parametrizations. We find that for disc fluids with constant adiabatic index r, super-reflection and mode growth depend on the gradient of the effective vortensity, ζ eff = ζ/S 2/Γ (where S ≡ P/Σ Γ measures the entropy): when dζ eff /dr > 0 at the corotation radius, wave absorption leads to amplification of the p-mode. Our calculations show that the lowest order p-modes with azimuthal wave number m = 2, 3, 4, ... have the largest growth rates, with the frequencies approximately in (but distinct from) the 2:3:4... commensurate ratios. We discuss the implications of our results for the high-frequency quasi-periodic oscillations observed in accreting black hole systems.
The Dirichlet problem for higher order equations in composition form

The present paper commences the study of higher order differential equations in composition form. Specifically, we consider the equation Lu=divB⁎∇(adivA∇u)=0, where A and B are elliptic matrices with complex-valued bounded measurable coefficients and a is an accretive function. Elliptic operators of this type naturally arise, for instance, via a pull-back of the bilaplacian Δ2 from a Lipschitz domain to the upper half-space. More generally, this form is preserved under a Lipschitz change of variables, contrary to the case of divergence-form fourth-order differential equations. We establish well-posedness of the Dirichlet problem for the equation Lu=0, with boundary data in L2, and with optimal estimates in terms of nontangential maximal functions and square functions.
Nephrolithiasis and Risk of Hypertension

A positive association between nephrolithiasis and blood pressure has been suggested in previous studies. However, controversy remains, due to methodological problems in some of the previous studies and absence of prospective data. We evaluated the relationship between nephrolithiasis and the risk of hypertension in a cohort of 51,529 men followed prospectively for 8 years. Information was obtained by biennial mailed questionnaires. At baseline in 1986, 4111 (8.0%) subjects reported a history of nephrolithiasis and 11,623 (22.6%) a diagnosis of hypertension. A positive association was found between the two disorders (age adjusted odds ratio [OR]: 1.31; 95% confidence interval [CI]: 1.30 to 1.32). Among men who reported both disorders, 79.5% reported that the occurrence of nephrolithiasis was prior to or concomitant with the diagnosis of hypertension. Among men without hypertension at baseline, the odds ratio for incident hypertension in men with a history of nephrolithiasis compared with those without was 1.29 (95% CI: 1.12 to 1.41; adjusted for age, body mass index, and intake of calcium, sodium, potassium, magnesium, and alcohol). The occurrence of incident nephrolithiasis during follow-up was similar in men with hypertension at baseline compared with that in men without (adjusted OR: 0.99, 95% CI: 0.82 to 1.21). These data support the hypothesis that prior occurrence of nephrolithiasis increases the risk of subsequent hypertension.
Physics of strongly magnetized neutron stars

There has recently been growing evidence for the existence of neutron stars possessing magnetic fields with strengths that exceed the quantum critical field strength of 4.4 × 1013 G, at which the cyclotron energy equals the electron rest mass. Such evidence has been provided by new discoveries of radio pulsars having very high spin-down rates and by observations of bursting gamma-ray sources termed magnetars. This paper will discuss the exotic physics of this high-field regime, where a new array of processes becomes possible and even dominant and where familiar processes acquire unusual properties. We review the physical processes that are important in neutron star interiors and magnetospheres, including the behaviour of free particles, atoms, molecules, plasma and condensed matter in strong magnetic fields, photon propagation in magnetized plasmas, free-particle radiative processes, the physics of neutron star interiors and field evolution and decay mechanisms. Application of such processes in astrophysical source models, including rotation-powered pulsars, soft gamma-ray repeaters, anomalous x-ray pulsars and accreting x-ray pulsars will also be discussed. Throughout this review, we will highlight the observational signatures of high magnetic field processes, as well as the theoretical issues that remain to be understood.
Efficient synthesis of several methylene-expanded oxetanocin nucleoside analogues

Abstract S -Glycidol 4 has been converted by a direct route via the dihydrofuran-3-methanols 9ab into a series of methylene-expanded oxetanocin nucleoside analogues, e.g., analogues of the normal nucleosides 2 and the known antiviral nucleosides, AZT, FdT, and ddC, 3 .
Engines of Growth: Domestic and Foreign Sources of Innovation

Abstract We examine productivity growth since World War II in the five leading research economies: West Germany, France, the United Kingdom, Japan, and the United States. Data on the capital-output ratio suggest that these countries grew as they did because of their ability to adopt more productive technologies, not because of capital-deepening per se. We use a multicountry model of technological innovation and diffusion which nests the cases of endogenous and exogenous growth to simulate the growth of the five countries, given initial productivity levels in 1950 and research efforts in the subsequent four decades. Based on plausible assumptions about ‘technology gaps’ that existed among these countries in 1950 the exogenous growth version of the model explains their growth experiences more successfully. Specifically, the simulations capture the magnitude of the slowdown in German, French, and Japanese productivity growth and the relative constancy of U.K. and U.S. growth.
Solvent-free Sonogashira coupling reaction via high speed ball milling

Herein, we report on the solvent-free Sonogashira reaction utilizing high speed ball milling. Sonogashira coupling of a variety of para substituted aryl halides were performed with trimethylsilylacetylene or phenylacetylene. We observed that iodo and bromo substituted aromatics successfully undergo Sonogashira coupling. However, chloro and fluoro substituted aryl compounds were unreactive. Conducting the coupling reaction in the absence of copper iodide led to low yields. Alternately, if the reaction is conducted with a copper ball in a copper vial in lieu of copper iodide, the coupling product is observed in high yields. This demonstrates the first report on the use of the vial and ball material as a catalyst in a ball milled chemical reaction.
Validation of Active Strain Measurements in Composites Using Mach-Zehnder Interferometry with Embedded Optical Fibers

This article reports the validation of active strain measurements in a vibrating composite lattice structure using Mach-Zehnder interferometry with embedded optical fibers. Optical fibers were used as internal strain sensors by embedding them in a highly flexible graphite/bismaleimide lattice structure to experimentally determine the dynamic response of the lattice. This is an extension of work previously reported on the natural response of a graphite/bismaleimide lattice structure with an optical fiber attached to the surface. The advanced composite lattice structure is a half-scale model of the aluminum grid used for active control studies at the Air Force Astronautics Laboratory
Collaboration Networks, Structural Holes, and Innovation: A Longitudinal Study:

To assess the effects of a firm's network of relations on innovation, this paper elaborates a theoretical framework that relates three aspects of a firm's ego network—direct ties, indirect ties, an...
The untwisted stabilizer in simple current extensions

Abstract A method is presented to compute the order of the untwisted stabilizer of a simple current orbit, as well as some results about the properties of the resolved fields in a simple current extension.
On S-duality for Non-Simply-Laced Gauge Groups

We point out that for Script N = 4 gauge theories with exceptional gauge groups G_2 and F_4 the S-duality transformation acts on the moduli space by a nontrivial involution. We note that the duality groups of these theories are the Hecke groups with elliptic elements of order 6 and 4, respectively. These groups extend the Γ_0(3) and Γ_0(2) subgroups of SL(2,ℤ) by elements with a non-trivial action on the moduli space. We show that under a certain embedding of these gauge theories into string theory, the Hecke duality groups are represented by T-duality transformations.
No horizons in pp-waves

We argue that pp-wave backgrounds can not admit event horizons. We also comment on pp-wave generalizations which would admit horizons and show that there exists a black string solution which asymptotes to a five dimensional plane wave background.
Does Public Insurance Crowd out Private Insurance

The cost of expanding public sector health programs depends critically on the extent to which public eligibility will cover just the uninsured, or will crowd out existing private insurance coverage. We estimate the extent of crowd-out arising from the expansions of Medicaid to pregnant women and children over the 1987–1992 period. We estimate that approximately 50 percent of the increase in Medicaid coverage was associated with a reduction in private insurance coverage. This occurred largely because employees took up employer-based insurance less frequently. There is also some evidence that employers contributed less for insurance and that workers dropped coverage of dependents.
Secondary Cytoreductive Surgery for Localized, Recurrent Epithelial Ovarian Cancer: Analysis of Prognostic Factors and Survival Outcome

BACKGROUND. The objective of this study was to evaluate the role of secondary cytoreductive surgery in the outcome of patients who had recurrent epithelial ovarian carcinoma that was limited to ≤5 recurrence sites within the abdomen or pelvis on preoperative imaging studies and attempt to define selection criteria associated with improved survival, with specific attention to the number of lesions suspicious for recurrent disease. METHODS. Patients who underwent secondary surgical cytoreduction for recurrent epithelial ovarian cancer between September 1997 and March 2005 were identified retrospectively from tumor registry databases. Study inclusion criteria required a complete clinical response to primary therapy, ≥12 months between initial diagnosis and recurrence, and ≤5 recurrence sites on preoperative imaging studies. Univariate and multivariate logistic regression analyses were used to evaluate the effect of clinicopathologic variables on overall postrecurrence survival. RESULTS. Fifty-five patients met the study inclusion criteria. The median patient age at recurrence was 57.7 years, and the median diagnosis-to-recurrence interval was 32 months (range, 12–164 months). Complete cytoreduction was achieved in 41 patients (74.5%). On multivariate analysis, the statistically significant and independent predictors of overall survival were a diagnosis-to-recurrence interval ≥18 months (median survival, 49 months vs 3 months; P < .01), the number of radiographic recurrence sites (median survival, 50 months for patients with 1 or 2 sites vs 12 months for patients with 3 to 5 sites; P < .03), and residual disease (median survival, 50 months for patients with no macroscopic residual disease vs 7.2 months for patients with macroscopic residual disease; P < .01). Age, tumor grade, histology, CA-125 level, ascites, and tumor size were not associated significantly with survival. CONCLUSIONS. The current data supported the definition of localized recurrent ovarian cancer as patients with 1 or 2 radiographic recurrence sites. In this select population, a diagnosis-to-recurrence interval ≥18 months and complete secondary surgical cytoreduction, which was achievable in the majority of patients, were associated with a median postrecurrence survival of approximately 50 months. Cancer 2007. © 2007 American Cancer Society.
The New Price to Play: Are Passive Online Media Users Bound By Terms of Use?

When individuals turn on the television, listen to the radio, or purchase newspapers, they are not forming contractual relationships. Yet, almost without exception, online readers, viewers and listeners are required to enter into “terms of use” contracts. These ubiquitous agreements are generally unfavorable for the user in areas of intellectual property rights and privacy. In addition, the terms often restrict users’ behavior and their ability to litigate any disputes with a Web site. In analyzing the implications of contracts for Web site users, this article examines whether courts have recognized a distinction between online consumers, interactive users, and “passive media users”—online readers, listeners or viewers who engage in little, if any, of the activity traditionally required to form contracts. Case law reveals a frequent de facto exemption from online agreements for passive media users, but not highly interactive users. This exemption could be formally recognized to benefit all parties to a co...
De Sitter spacetimes from warped compactifications of IIB string theory

Abstract We continue our study of codimension two solutions of warped spacetime varying compactifications of string theory. In this Letter we discuss a non-supersymmetric solution of the classical type IIB string theory with de Sitter gravity on a codimension two uncompactified part of spacetime. A non-zero positive value of the cosmological constant is induced by the presence of non-trivial stringy moduli, such as the axion–dilaton system for the type IIB string theory. Furthermore, the naked singularity of the codimension two solution is resolved by the presence of a small but non-zero cosmological constant.