cssi/SciSciGPT-SciSciNet huggingface dataset:
Food fortification with folic acid and rate of multiple births, 1994-2000.

BACKGROUND Since fortification of cereal grain products with synthetic folic acid (FA) became mandatory in January 1998, women in the United States who have become pregnant have been exposed to a higher level of FA than women who became pregnant previously. Some studies have suggested that increased FA consumption might increase the risk of multiple gestation pregnancies. METHODS Women who had a live birth in Kaiser Foundation Health Plan hospitals from January 1, 1994 through December 31, 2000; all multiple births; and the use of ovulation-inducing drugs were ascertained from electronic databases. Medical records of a sample of women with multiple births who did not use ovulation-inducing drugs were reviewed to determine whether they used assisted reproductive technology. Exposure to FA-fortified foods was based on date of delivery. RESULTS The rate of multiple births increased from 13.6 to 14.8 per 1000 live births from 1994 through 2000. The percentage of women who had a multiple birth and who filled a prescription for an ovulation-inducing drug in the 12 months before delivery increased from a low of 6.6% in 1994 to a high of 14.9% in 2000. After excluding women using ovulation-inducing drugs, the increased rate of multiple births was no longer observed. CONCLUSIONS While the rates of multiple births have increased since FA fortification became mandatory, this increase can be explained by the increased use of ovulation-inducing drugs. Our findings show no relationship between food fortification with FA and the rates of multiple births in this large, managed health care population. Birth Defects Research (Part A), 2004. Published 2004 Wiley-Liss, Inc.
A study of process arrival patterns for MPI collective operations

Process arrival pattern, which denotes the timing when different processes arrive at an MPI collective operation, can have a significant impact on the performance of the operation. In this work, we characterize the process arrival patterns in a set of MPI programs on two common cluster platforms, use a micro-benchmark to study the process arrival patterns in MPI programs with balanced loads, and investigate the impacts of different process arrival patterns on collective algorithms. Our results show that (1) the differences between the times when different processes arrive at a collective operation are usually sufficiently large to affect the performance; (2) application developers in general cannot effectively control the process arrival patterns in their MPT programs in the cluster environment: balancing loads at the application level does not balance the process arrival patterns; and (3) the performance of collective communication algorithms is sensitive to process arrival patterns. These results indicate that process arrival pattern is an important factor that must be taken into consideration in developing and optimizing MPI collective routines. We propose a scheme that achieves high performance with different process arrival patterns, and demonstrate that by explicitly considering process arrival pattern, more efficient MPI collective routines than the current ones can be obtained.
Improved Asymptotics for Zeros of Kernel Estimates via a Reformulation of the Leadbetter-Cryer Integral

Abstract The expected number of false inflection points of kernel smoothers is evaluated. To obtain the small noise limit, we use a reformulation of the Leadbetter-Cryer integral for the expected number of zero crossings of a differentiable Gaussian process.
Nonlinearity and stationarity of inflation rates: evidence from the euro-zone countries

Earlier studies hardly reject the hypothesis of a unit root in inflation. Few studies have examined the possibility of nonlinearity in inflation and tested nonlinear stationarity of the inflation rates. This study thus intends to fill the gap. This study utilizes the tests for nonlinearity along with the unit root tests that allow for nonlinearity in the variables to examine the stationarity of inflation rates of 12 European countries that formed the Euro Zone (EZ) later in the sample period. The results suggest that the majority of these countries’ inflation rates can be characterized by mean reversion during the floating exchange rate period. Many of them appear to be nonlinear stationary. This finding is essential in conducting applied economic studies for these countries, when constructing models whose validity relies on whether or not inflation is stationary. The results of this study also imply that shocks to inflation have a transitory effect on inflation in the euro area. Therefore, it would be le...
Ripple-induced energetic particle loss in tokamaks

The threshold for stochastic transport of high energy trapped particles in a tokamak due to toroidal field ripple is calculated by explicit construction of primary resonances, and a numerical examination of the route to chaos. Critical field ripple amplitude is determined for loss. The expression is given in magnetic coordinates and makes no assumptions regarding shape or up‐down symmetry. An algorithm is developed including the effects of prompt axisymmetic orbit loss, ripple trapping, convective banana flow, and stochastic ripple loss, which gives accurate ripple loss predictions for representative Tokamak Fusion Test Reactor [R. Hawryluk, Plasma Phys. Controlled Fusion 33, 1509 (1991)] and International Thermonuclear Experimental Reactor [K. Tomabechi, Proceedings of the 12th International Conference on Plasma Physics and Controlled Nuclear Fusion Research (International Atomic Energy Agency, Vienna, 1989), Vol. 3, p. 214] equilibria. The algorithm is extended to include the effects of collisions and d...
The complex relationship of genetics, groups, and health: what it means for public health.

The author argues that public health practice must acknowledge that genetic variation affects the health of populations directly and, even more important, indirectly, being mediated by both the social positioning of groups and by widely held beliefs that genetic information is deterministic. The complexity of this relationship among genetics, groups, and health, as well as the multiple opportunities for misuse and misunderstanding, also increases the importance of involving communities and populations in public health research and practice.
Do `thinly-traded¿ stocks benefit from specialist intervention?

Abstract This paper addresses the issue of the optimal trading system for less actively traded (i.e., ‘thinly-traded’) stocks. We compare the performance of a pure order driven market with limit order book (POD) with that of a hybrid order driven market with specialist and limit order book (HOD). We find that the HOD system offers superior performance along several dimensions of market quality. In particular, the specialist-based system offers lower execution costs, greater depth, a significant increase in the depth-to-spread ratio, and lower adverse selection costs. Very ‘thinly-traded’ stocks benefit more than less inactive stocks from the adoption of a hybrid trading system both in terms of greater liquidity and in terms of lower adverse selection costs.
Beginner's guide to indexes to the Nineteenth Century U.S. Serial Set

Abstract The Nineteenth Century U.S. Serial Set is a vast repository of information on the United States. Unfortunately, the indexes to it - Poore, Ames, Tables and Index, Documents Catalogs, and the Checklist — tend to be somewhat difficult to understand and use. This paper gives a brief explanation of the format and use of each index.
The Prompt Gamma-Ray and Afterglow Energies of Short-Duration Gamma-Ray Bursts

I present an analysis of the γ-ray and afterglow energies of a complete sample of 16 short-duration GRBs with prompt X-ray follow-up. I find that 80% of the bursts exhibit a linear correlation between their γ-ray fluence and the afterglow X-ray flux normalized to t = 1 day, a proxy for the kinetic energy of the blast wave (FX,1 F). An even tighter correlation is evident between the isotropic γ-ray energy, Eγ,iso, and the X-ray luminosity at t = 1 day, LX,1, for the subset of 12 bursts with measured or constrained redshifts. The remaining 20% of the bursts have values of FX,1/Fγ that are suppressed by about 3 orders of magnitude, likely as a result of low circumburst densities; this has been noted based on a smaller sample by Nakar (2007). These results have several important implications: (1) the X-ray luminosity is generally a robust proxy for the blast wave kinetic energy, indicating νX > νc, and hence a circumburst density n 0.05 cm-3; (2) most short GRBs have a narrow range of γ-ray efficiency, with γ ≈ 0.1 and a spread of 0.3 dex; and (3) the isotropic-equivalent energies span 1048-1053 erg. Furthermore, I find tentative evidence for jet collimation (opening angle, θj ≈ 6°) in GRB 061006 leading to Eγ ≈ 4 × 1048 erg, similar to other short bursts with jet breaks. I find no clear evidence for a relation between the overall energy release and host galaxy type, but a positive correlation with duration may be present, albeit with a large scatter. Finally, I note that the low-density hypothesis for the outliers can be explained in the context of neutron star-neutron star (NS-NS) mergers in globular clusters (as opposed to large kick velocities), but present short GRB rate estimates may be an order of magnitude too large for this scenario to work.
Potential application of the Los Alamos free electron laser: high-temperature superconductors

An improved understanding of High-Temperature Superconductors (HTSCs) should result from the direct investigation of the energy gap associated with the superconducting state. An adaptation of the classic transmission experiments using a broadly tunable Free- Electron Laser (FEL) to irradiate the HTSC single crystals or thin films as a function of photon energy and sample temperature is described. In particular, the Los Alamos FEL has a projected tuning range of 9-160..mu..m (140-8 MeV). In addition, its 10 to 20-ps micropulse structure, linear polarization, coherence, monochromaticity, focusability and peak power features should make it a unique research tool for probing HTSCs with critical temperature (T/sub c/) from /approximately/30 to /approximately/400 K (depending on the energy gaps involved). 14 refs., 4 figs., 2 tabs.
Assessing JIT Performance: An Econometric Approach

ABSTRACT: This paper uses a sample of 131 just‐in‐time (JIT) firms and their matched non‐JIT firms obtained from Kinney and Wempe with 1977–1995 Compustat data to assess whether the relationship between JIT adoption and firm performance is endogenous. Results indicate a significant positive association between JIT adoption and firm performance and strongly indicate that the decision to adopt JIT is endogenous. We also show that asset productivity, sales growth, and leverage, are important in explaining the effect of JIT adoption on performance and that firm characteristics are an important contributor to unobserved heterogeneity. Furthermore, the econometric analyses in the form of both Wooldridge 2SLS and Heckman approaches suggest that the underlying relationship between JIT adoption and performance is much stronger after controlling for endogeneity and self‐selection bias and that OLS estimates are indeed biased.
On CR embeddings of strictly pseudoconvex hypersurfaces into spheres in low dimensions

It follows from the 2004 work of the first author, X.Huang, and D. Zaitsev that any local CR embedding $f$ of a strictly psedoconvex hypersurface $M^{2n+1}\subset\bC^{n+1}$ into the sphere $\bS^{2N+1}\subset \bC^{N+1}$ is rigid, i.e.\ any other such local embedding is obtained from $f$ by composition by an automorphism of the target sphere $\bS^{2N+1}$, {\it provided} that the codimension $N-n<n/2$. In this paper, we consider the limit case $N-n=n/2$ in the simplest situation where $n=2$, i.e.\ we consider local CR embeddings $f\colon M^5\to \bS^7$. We show that there are at most two different local embeddings, up to composition with an automorphism of $\bS^7$. We also identify a subclass of 5-dimensional, strictly pseudoconvex hypersurfaces $M^5$ in terms of their CR curvatures such that rigidity holds for local CR embeddings $f\colon M^5\to \bS^7$.
Sensitivity analysis of aeroelastic response of a wing using piecewise pressure representation

A piecewise, panel-based, pressure representation is incorporated to improve the fidelity of an existing wing aeroelastic model, including the sensitivity of the wing static aeroelastic response with respect to various shape parameters. The formulation is quite general and is easily adaptable to any aerodynamics and structural analysis codes desired. An interface code written earlier to transfer information between aerodynamic and structures modules using a global pressure representation has been modified to improve the representation of the calculated pressures using piecewise representations. These improvements are designed to overcome some drawbacks of the earlier representation as well as provide a more accurate representation of the aerodynamic loads to the structures module. A variety of refinements has been attempted to study their effectiveness. A program to combine the local sensitivities, such as the sensitivity of the stiffness matrix or the aerodynamic kernel matrix, into global sensitivity derivatives is developed. Results with excellent accuracy have been produced for large integrated quantities such as wingtip deflection and trim angle of attack. In all cases, accuracy is dependent on the size of the derivatives relative to the size of the quantity itself. The piecewise pressure approaches improved the fidelity of the model and the accuracy of the results at little or no additional computational expense.
Impact of day of admission on mortality and other outcomes in upper GI hemorrhage: a nationwide analysis.

Background Studies have reached varying conclusions regarding the association between day of admission and outcomes in patients with upper GI hemorrhage (UGIH). Objectives To evaluate whether important outcomes in UGIH, including in-hospital mortality, differ between patients admitted on weekends versus weekdays. Design and Setting Retrospective cohort study by using the 2009 Nationwide Inpatient Sample. Patients Patients were included if they were adults with a principal diagnosis of acute UGIH. Patients admitted between midnight Friday and midnight Sunday were classified as weekend admissions. Main Outcome Measurements In-hospital mortality, in-hospital endoscopy, endoscopic therapy, length of stay, and total hospitalization charges. Results The study included 199,008 patients with nonvariceal UGIH and 3251 patients with variceal UGIH. Compared with patients admitted on weekdays, patients with nonvariceal UGIH admitted on weekends had similar adjusted in-hospital mortality rates (odds ratio [OR] 1.11; 95% confidence interval [CI], 0.93–1.30), endoscopic therapy rates (OR 0.98; 95% CI, 0.92-1.04), and length of stay ( P = .09), but had lower early endoscopy rates (within 24 hours)(OR 0.64; 95% CI, 0.60–0.67), lower in-hospital endoscopy rates (OR 0.84; 95% CI, 0.78-0.91), and higher hospitalization charges (mean increase, $1558; P = .01). Patients with variceal UGIH admitted on weekends and weekdays did not differ in any of these outcomes. Limitations Retrospective data, administrative database. Conclusions Compared with patients admitted on weekdays, patients with nonvariceal UGIH admitted on weekends had similar mortality rates and lengths of stay, but lower endoscopy rates and higher hospitalization charges. Patients with variceal GI hemorrhage had similar outcomes regardless of day of admission.
Peripherally-substituted polydimethylsiloxane phthalocyanines: a novel class of liquid materials

Isotropic liquid phthalocyanine compounds with peripheral polydimethylsiloxane oligomer substitution were synthesized and found to have a unique combination of thermorefractive and nonlinear optical properties along with unusual metal substitution reactivity and aggregation behavior.
Use of Estrogen for Prevention and Treatment of Osteoporosis

Two decades of experience leave no doubt that sustained administration of estrogen to menopausal women conserves bone throughout the skeleton. Such conservation should theoretically protect against osteoporotic fracture, and, indeed, epidemiological studies support the view that long-term estrogen replacement does afford women such protection. On the other hand, uncertainty remains about many aspects of this issue. Questions persist regarding the therapeutic schedule itself: the type, dose, and mode of administration of estrogen that is optimal. Other questions concern the individuals who will receive estrogen: the age at which treatment begins, its duration, and the consequence of adding progestins to the treatment regimen. The level of uncertainty for these questions grows considerably when the end point is fracture protection rather than bone mass. In this chapter, I discuss the therapeutic use of estrogen to prevent or treat osteoporosis.
A multivariable adaptive controller for a quadrotor with guaranteed matching conditions

This paper develops an adaptive control system for a quadrotor unmanned aerial vehicle. It employs a state feedback output tracking design for multi-input multi-output systems, using a less restrictive matching condition than a state tracking design, and offers a simpler controller structure than an output feedback design. Some key characteristics of the quadrotor dynamics are derived for adaptive control design which deals with system uncertainties from changing operating points. The plant-model matching is ensured despite of system parameter uncertainties which cannot be handled by an existing state tracking design. The adaptive law is based on a parametrization using an LDS decomposition of the high-frequency gain matrix, which ensures closed-loop stability and asymptotic output tracking. A simulation study is carried out on the nonlinear quadrotor model, and results are presented to demonstrate the desired adaptive system performance.
Purchasing population health: Aligning financial incentives to improve health outcomes

Abstract OBJECTIVE: To review the concept of population health, including its definition, measurement, and determinants, and to suggest an approach for aligning financial incentives toward this goal. DATA SOURCE, STUDY DESIGN, DATA EXTRACTION: Literature review, policy analysis PRINCIPAL FINDINGS: The article presents the argument that a major reason for our slow progress toward health outcome improvement is that there is no operational definition of population health and that financial incentives are not aligned to this goal. Current attempts at process measures as indicators of quality or outcome are not adequate for the task. It is suggested that some measure of health-adjusted life expectancy be adopted for this purpose, and that integrated delivery systems and other agents responsible for nonmedical determinants be rewarded for improvement in this measure. This will require the development of an investment portfolio across the determinants of health based on relative marginal return to health, with horizontal integration strategies across sectoral boundaries. A 20-year three-phase development strategy is proposed, including components of research and acceptance, integrated health system implementation, and cross-sectoral integration. CONCLUSIONS: The U.S. health care system is a $1 trillion industry without a definition of its product. Until population outcome measures are developed and rewarded for, we will not solve the twenty-first century challenge of maximizing health outcome improvement for the resources available.
Experimental spectral measurements of heavy K-edge filtered beams for x-ray computed mammotomography

A dual modality computed mammotomography (CmT) and single photon emission computed tomography (SPECT) system for dedicated 3D breast imaging is in development. Using heavy K-edge filtration, the CmT component narrows the energy spectrum of the cone-shaped x-ray beam incident on the patient's pendant, uncompressed breast. This quasi-monochromatic beam is expected to improve discrimination of tissue with similar attenuation coefficients while restraining absorbed dose to below that of dual view mammography. Previous simulation studies showed the optimal energy that maximizes dose efficiency for a 50/50% adipose/glandular breast is between 30 and 40 keV. This study experimentally validates these results using pre-breast and post-breast spectral measurements made under tungsten tube voltages between 40 and 100 kVp using filter materials with K-edge values ranging from 15 to 70 keV. Different filter material thicknesses are used, approximately equivalent to the 200th and 500th attenuating value layer (VL) thickness. Cerium (K = 40.4 keV) filtered post-breast spectra for 8-18 cm breasts are measured for a range of breast compositions. Figures of merit include mean beam energy, spectral full-width at tenth-maximum, beam hardening and dose for the range of breast sizes. Measurements corroborate simulation results, indicating that for a given dose, a 200th VL of cerium filtration may have optimal performance in the dedicated mammotomography paradigm.
Bonding in the BaPdSn3 Structure

La structure a faces centrees BaPdSn 3 contient des atomes de Sn dans les sites tetraedriques et pyramidaux a base carree, et du palladium en environnement pyramidal a base carree. Une decomposition geometrique du materiau est utilisee pour obtenir sa structure electronique
Assembly sequencing with toleranced parts

The goal of assembly sequencing is to plan a feasible series of operations to construct a product from its individual parts. Previous research has thoroughly investigated assembly sequencing under the assumption that parts have nominal geometry. This paper considers the case where parts have toleranced geometry. Its main contribution is an efficient procedure that decides if a product admits an assembly sequence with infinite translations that is feasible for all possible instances of the components within the specified tolerances. If the product admits one such sequence, the procedure can also generate it. For the cases where there exists no such assembly sequence, another procedure is proposed which generates assembly sequences that are feasible only for some values of the toleranced dimensions. If this procedure produces no such sequence, then no instance of the product is assemblable. Finally, this paper analyzes the relation between assembly and disassembly sequences in the presence of toleranced parts. This work assumes a simple, but non-trivial tolerance language that falls short of capturing all imperfections of a manufacturing process. Hence, it is only one step toward assembly sequencing with toleranced parts.
The Etiologic Significance of Deafness in Ulcerative Colitis

The case histories of several patients whose ulcerative colitis was preceded by partial deafness are presented. It is assumed that the partial deafness had an etiological significance and a series of four steps leading from the communication difficulties created by the deafness to the ulcerative colitis is described. Emphasis is placed upon the role of the partial deafness in the creation of a potentially objectless state which predisposes to the experiencing of the affect depression-withdrawal under conditions of additional stress. Presumably somatic correlates of this affect interact with unknown somatic vulnerabilities to produce ulcerative colitis.
Structure and heats of formation of iodine fluorides and the respective closed-shell ions from CCSD(T) electronic structure calculations and reliable prediction of the steric activity of the free-valence electron pair in ClF6-, BrF6-, and IF6-.

Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for IF, IF2−, IF2+, IF3, IF4−, IF4+, IF5, IF6−, IF6+, IF7, IF8−, BrF6−, and ClF6− from coupled cluster theory [CCSD(T)] calculations with effective-core potential correlation-consistent basis sets for I. In order to achieve near chemical accuracy (±1 kcal/mol), three corrections were added to the complete basis set binding energies based on frozen-core coupled-cluster theory energies: a correction for core-valence effects, a correction for scalar relativistic effects, and a correction for first-order atomic spin−orbit effects. Vibrational zero-point energies were computed at the coupled-cluster level of theory except for IF6−, IF7, and IF8−. The calculated heats of formation for the neutral and ionic IFn fluorides were used to predict fluoride affinities. It is shown that high-level calculations are required to predict correctly the steric activity of the free-valence electron pair on the central atoms in IF6− (C3v), BrF6− (Oh...
Anomaly mediation in supergravity theories

We consider the effects of anomalies on the supersymmetry-breaking parameters in supergravity theories. We construct a supersymmetric expression for the anomaly-induced terms in the 1PI effective action; we use this result to compute the complete one-loop formula for the anomaly-induced gaugino mass. The mass receives contributions from the super-Weyl, Kahler, and sigma-model anomalies of the supergravity theory. We point out that the anomaly-mediated gaugino mass can be affected by local counterterms that cancel the super-Weyl-Kahler anomaly. This implies that the gaugino mass cannot be predicted unless the full high-energy theory is known.
Millimeter-Wave Self Mixing Oscillators,

Self-oscillating mixers in both dielectric and waveguide cavities have veen investigated in the 60 GHz frequency range. The deveces consist of negative resistance diodes of GaAs and InP material coupled to waveguide cavities or high resistivity dielectric cavities such as silicon or Al2O3. Experimental measurements show that these devices have a sensitivity in the order of −80 dBm with the intermediate frequency at 60 MHz and an IF bandwidth of 120 MHz. Applications are suggested based on minimum detectable signal and RF power capabilities for systems requiring small size and low cost.
Unsteady numerical simulations of radial temperature profile redistribution in a single-stage turbine

Experimental data taken from gas turbine combustors indicate that the flow exiting the combustor can contain both circumferential and radial temperature gradients. A significant amount of research recently has been devoted to studying turbine flows with inlet temperature gradients, but no total pressure gradients. Less attention has been given to flows containing both temperature and total pressure gradients at the inlet. The significance of the total pressure gradients is that the secondary flows and the temperature redistribution process in the vane blade row can be significantly altered. Experimental data previously obtained in a single-stage turbine with inlet total temperature and total pressure gradients indicated a redistribution of the warmer fluid to the pressure surface of the airfoils, and a severe underturning of the flow at the exit of the stage. In a concurrent numerical simulation, a steady, inviscid, three-dimensional flow analysis was able to capture the redistribution process, but not the exit flow angle distribution. In the current research program, a series of unsteady two- and three-dimensional Navier-Stokes simulations have been performed to study the redistribution of the radial temperature profile in the turbine stage. The three-dimensional analysis predicts both the temperature redistribution and the flow underturning observed in the more » experiments. « less
The Value of Peripatetic Economists: A Sesqui‐Difference Evaluation of Bob Gregory

Does a country benefit from temporarily importing human capital? Do foreign academic visitors generate additional scholarly research on local issues? I use a survey in which visitors to ANU's Economics Program described their research before and after their visit and designated an otherwise similar non-visitor as a control. Matching to controls may thus be along observable and unobservable characteristics. These visits have a highly significant impact on the visitor's subsequent research, redirecting it toward Australia. Valuing this extra research based on scholarly citations received and the effects of citations on salaries shows substantial monetary gains.
A fast method for power spectrum and foreground analysis for 21 cm cosmology

We develop and demonstrate an acceleration of the Liu and Tegmark quadratic estimator formalism for inverse variance foreground subtraction and power spectrum estimation in 21 cm tomography from $\mathcal{O}({N}^{3})$ to $\mathcal{O}(N\mathrm{log}﻿N)$, where $N$ is the number of voxels of data. This technique makes feasible the megavoxel scale analysis necessary for current and upcoming radio interferometers by making only moderately restrictive assumptions about foreground models and survey geometry. We exploit iterative and Monte Carlo techniques and the symmetries of the foreground covariance matrices to quickly estimate the 21 cm brightness temperature power spectrum, $P({k}_{\ensuremath{\parallel}},{k}_{\ensuremath{\perp}})$, the Fisher information matrix, the error bars, the window functions, and the bias. We also extend the Liu and Tegmark foreground model to include bright point sources with known positions in a way that scales as $\mathcal{O}[(N\mathrm{log}﻿N)\ifmmode\times\else\texttimes\fi{}(N\text{ }\mathrm{\text{point sources}})]\ensuremath{\le}\mathcal{O}({N}^{5/3})$. As a first application of our method, we forecast error bars and window functions for the upcoming 128-tile deployment of the Murchinson Widefield Array, showing that 1000 hours of observation should prove sufficiently sensitive to detect the power spectrum signal from the Epoch of Reionization.
Nutrition, sex, and fetal lung maturation.

Extract: Maternal nutrition and the sex of a fetus appear to have important influences on fetal lung maturation and on the neonatal development of hyaline membrane disease. Amniotic fluid lecithin to sphingomyelin ratios and shake test values were greater in undernourished than in overnourished pregnancies after midgestation. There was a similar relation between levels of maternal nutrition and structural variables of fetal lung maturity. Using the same variables, the lungs of female fetuses matured somewhat more rapidly than the lungs of males. Hyaline membrane disease was almost twice as common in infants who died after overnourished gestations as in those who had undernourished mothers.
Branching process approach for 2-SAT thresholds

It is well known that, as n tends to ∞, the probability of satisfiability for a random 2-SAT formula on n variables, where each clause occurs independently with probability α / 2 n , exhibits a sharp threshold at α = 1. We study a more general 2-SAT model in which each clause occurs independently but with probability α i / 2 n , where i ∈ {0, 1, 2} is the number of positive literals in that clause. We generalize the branching process arguments used by Verhoeven (1999) to determine the satisfiability threshold for this model in terms of the maximum eigenvalue of the branching matrix.
RANDOM SUBSETS SUPPORT LEARNING A MIXTURE OF HEURISTICS

Problem solvers, both human and machine, have at their disposal many heuristics that may support effective search. The efficacy of these heuristics, however, varies with the problem class, and their mutual interactions may not be well understood. The long-term goal of our work is to learn how to select appropriately from among a large body of heuristics, and how to combine them into a mixture that works well on a specific class of problems. The principal result reported here is that randomly chosen subsets of heuristics can improve the identification of an appropriate mixture of heuristics. A self-supervised learner uses this method here to learn to solve constraint satisfaction problems quickly and effectively.
Depth-dependent biomechanical and biochemical properties of fetal, newborn, and tissue-engineered articular cartilage

Abstract Adult articular cartilage has depth-dependent mechanical and biochemical properties which contribute to zone-specific functions. The compressive moduli of immature cartilage and tissue-engineered cartilage are known to be lower than those of adult cartilage. The objective of this study was to determine if such tissues exhibit depth-dependent compressive properties, and how these depth-varying properties were correlated with cell and matrix composition of the tissue. The compressive moduli of fetal and newborn bovine articular cartilage increased with depth ( p 0.0 5 ) by a factor of 4–5 from the top 0.1 mm (28±13 kPa, 141±10 kPa, respectively) to 1 mm deep into the tissue. Likewise, the glycosaminoglycan and collagen content increased with depth (both p 0.0 0 1 ), and correlated with the modulus (both p 0.0 1 ). In contrast, tissue-engineered cartilage formed by either layering or mixing cells from the superficial and middle zone of articular cartilage exhibited similarly soft regions at both construct surfaces, as exemplified by large equilibrium strains. The properties of immature cartilage may provide a template for developing tissue-engineered cartilage which aims to repair cartilage defects by recapitulating the natural development and growth processes. These results suggest that while depth-dependent properties may be important to engineer into cartilage constructs, issues other than cell heterogeneity must be addressed to generate such tissues.
Diaryl Ether Containing N-Hydroxycarbamates from Nitroso Cycloadducts.

Abstract Regioselective ring opening of N -hydroxycarbamate-derived nitroso cycloadducts by a copper-catalyzed allylic alkylation reaction was achieved and applied to the synthesis of a set of substituted diaryl ether containing compounds. Use of protected 3-hydroxybenzyl bromide allowed access to a late stage phenol intermediate after protection of the N -hydroxy moiety that was generated from the ring opening reaction. The diaryl ethers were then formed by copper-mediated coupling with arylboronic acids. After selective deprotection, alumina-promoted transcarbamoylation provided the target compounds. Previous results indicate that the compounds may possess significant inhibitory potency against the proinflammatory enzyme 5-lipoxygenase.
Computer architecture and very large problems

For the purposes of this paper, "very large problems" are defined by two properties: (1) There is an effectively unlimited amount of physics and of spatial detail which it would be useful to include if practical; and (2) the calculation must be completed in a limited number of hours. The best example is perhaps the global weather problem. We will obviously never put in all the energy sources or all the topography and we must obviously calculate faster than real time.
Relationship of production to reproductive performance in Ontario dairy cows: Herd level and individual animal descriptive statistics

Data were collected on reproductive, health and production events in 45 dairy herds distributed throughout southwestern and eastern Ontario. The data were collected between July 1990 and July 1993. The herds were serviced by 11 different veterinary practices. Herd size ranged from 19 to 231 lactating cows, but 90% of the herds consisted of fewer than 125 milking cows. Mean and median actual milk yields per cow per day were 46.0 and 52.3 lbs, respectively, with a minimum of 21.3 and maximum of 67.8 lbs. Mean and medium adjusted corrected milk yields were 56.0 and 62.3 lbs, reflecting mean and median average days in milk of 199.0 and 198.5 d, respectively. Mean and median days in milk at the first estrus were 85.1 and 83.9 d, respectively, at first service 94.0 and 88.9 d, and at conception 126.3 and 115.5 d. Mean and median percentages of days open > 120 were 27.7 and 23.1%, respectively. The mean estrus detection rate was 48.3%, with a minimum of 28.4% and a maximum of 64.2%. The mean first service conception rate was 48.2%, with a minimum of 27.0% and maximum of 72.1%. The mean overall conception rate was 46.7%, with a minimum of 29.8% and a maximum of 70.7%. Mean and median lactation lengths were 341.1 and 338.5 d and the mean and median average dry days were 62.0 and 67.0, respectively. The mean lactational removal rate was 20.6%, with a range of 4.3 to 40.5%. Reasons for culling were available for 1381 cows. Low production accounted for 23.7 % of the cullings; reproductive reasons, 20.6 %; dairy sales, 13.4%; mammary problems, 12.8%; and lameness, 9.9%. Lactational incidence rates for diseases were lower than previously reported for Ontario dairy herds. The most commonly used therapeutic agents were GnRH (10.5%) and PGF (11.7%).
LADAR detection statistics in the presence of pointing errors.

The probability of detection of optically rough targets with pulsed LADAR systems that use direct detection is considered. It is assumed that the LADAR operates under conditions of both unintentional pointing offset bias (i.e., bore-sight error) and jitter. Under these conditions the probabilities of detection of targets in both the near field and the far field of the collecting aperture (i.e., for resolved, partially resolved, and unresolved targets) and for both large and small photoelectron counts are derived, and in many cases of practical interest accurate, elementary analytic approximations that are useful for parametric system studies are obtained. A number of technical references are appended, in which some of the key results are derived. In particular, an interesting new mathematical result involving the complementary incomplete gamma function and an analytic expression for the probability distribution function of a signal photoelectron count obeying Bose–Einstein statistics (such as that arising from unresolved targets) immersed in Poisson noise is derived.
Symmetries and pre-metric electromagnetism

The equations of pre-metric electromagnetism are formulated as an exterior differential system on the bundle of exterior differential 2-forms over the spacetime manifold. The general form for the symmetry equations of the system is computed and then specialized to various possible forms for an electromagnetic constitutive law, namely, uniform linear, non-uniform linear, and uniform nonlinear. It is shown that in the uniform linear case, one has four possible ways of prolonging the symmetry Lie algebra, including prolongation to a Lie algebra of infinitesimal projective transformations of a real four-dimensional projective space. In the most general non-uniform linear case, the effect of non-uniformity on symmetry seems inconclusive in the absence of further specifics, and in the uniform nonlinear case, the overall difference from the uniform linear case amounts to a deformation of the electromagnetic constitutive tensor by the electromagnetic field strengths, which induces a corresponding deformation of the symmetry Lie algebra that was obtained in the linear uniform case. c
A Case for Automated Large Scale Semantic Annotation

Abstract This paper describes Seeker, a platform for large-scale text analytics, and SemTag, an application written on the platform to perform automated semantic tagging of large corpora. We apply SemTag to a collection of approximately 264 million web pages, and generate approximately 434 million automatically disambiguated semantic tags, published to the web as a label bureau providing metadata regarding the 434 million annotations. To our knowledge, this is the largest scale semantic tagging effort to date. We describe the Seeker platform, discuss the architecture of the SemTag application, describe a new disambiguation algorithm specialized to support ontological disambiguation of large-scale data, evaluate the algorithm, and present our final results with information about acquiring and making use of the semantic tags. We argue that automated large-scale semantic tagging of ambiguous content can bootstrap and accelerate the creation of the semantic web.
Giant impacts on early Mars and the cessation of the Martian dynamo

[1] Although Mars currently has no global dynamo-driven magnetic field, widespread crustal magnetization provides strong evidence that such a field existed in the past. The absence of magnetization in the younger large Noachian basins suggests that a dynamo operated early in Martian history but stopped in the mid-Noachian. Within a 100 Ma period, 15 giant impacts occurred coincident with the disappearance of the global magnetic field. Here we investigate a possible causal link between the giant impacts during the early and mid-Noachian and the cessation of the Martian dynamo at about the same time. Using three-dimensional spherical mantle convection models, we find that impact heating associated with the largest basins (diameters >2500 km) can cause the global heat flow at the core-mantle boundary to decrease significantly (10–40%). We suggest that such a reduction in core heat flow may have led to the cessation of the Martian dynamo.
THE SPATIAL AND TEMPORAL DEPENDENCE OF CORONAL HEATING BY ALFVÉN WAVE TURBULENCE

The solar atmosphere may be heated by Alfven waves that propagate up from the convection zone and dissipate their energy in the chromosphere and corona. To further test this theory, we consider wave heating in an active region observed on 2012 March 7. A potential field model of the region is constructed, and 22 field lines representing observed coronal loops are traced through the model. Using a three-dimensional (3D) reduced magnetohydrodynamics code, we simulate the dynamics of Alfven waves in and near the observed loops. The results for different loops are combined into a single formula describing the average heating rate Q as a function of position within the observed active region. We suggest this expression may be approximately valid also for other active regions, and therefore may be used to construct 3D, time-dependent models of the coronal plasma. Such models are needed to understand the role of thermal non-equilibrium in the structuring and dynamics of the Sun's corona.
Photochemistry of chloro‐2‐vinylstilbenes

Short irradiation at 300 nm of α-chloro- and β-chloro-2-vinylstilbene (20 and 21) leads to a mixture of 2-vinyltolane (35) and 2-vinylstilbene (1) accompanied by the cis- and trans-isomers of the starting compounds. Evidence is found for the occurrence of an ionic intermediate during the photolysis of 20 in methanol. At 360 nm, an additional, small amount of 1-chloro-endo- and 1-chloro-exo-6-phenylbenzobicyclo[3.1.0]hex-2-ene (39) is formed from 20. The elimination of hydrogen chloride also occurs during the irradiation of 2-(2-chlorovinyl)stilbene (23) and leads to 2-ethynylstilbene (41). The acetylenic compounds are photocyclized into 2-phenylnaphthalene (38). However, 2-(1-chlorovinyl)stilbene (22) reacts without loss of chlorine to give 1-chloro-exo-5-phenylbenzobicyclo[2.1.1]-hex-2-ene (40). This exceptional reaction mode is due to a much higher rate of photocyclization resulting from less distortion in the stilbene moiety and a preference for a conformation better suited to the reaction of the 2-(1-chlorovinyl)stilbene molecule. It is shown that both isomers of 22 can photocyclize into 40.
Measurement of pyrotechnic ignition energy by thermography

Measuring the laser energy required to ignite pyrotechnic pellets is complicated by several factors that are difficult to control or predict. These include reflection of part of the incident laser energy, reemission from the heated sample, and heat conduction away from the ignition site. In addition to these factors, it is often difficult to control and/or measure the incident laser power. High-speed thermographic recording of the temperature distribution in the test sample makes it possible to calculate the heat content of the test pellet at any instant. Thus, one can actually observe the laser heating and on-set of reaction in the pellet and avoid having to make measurements or assumptions to account for possible energy losses.
Director Quality and Firm Performance

Many financial economists argue that the board of directors' efficacy in the monitoring of managerial behavior depends upon the quality of the directors. Assuming that there is a link between the stock performance of target firms and the quality of their directors, we empirically categorize directors receiving additional directorships following a takeover as “above average” and “below average.” We then follow the stock performance of firms hiring new directors for three years after their hiring. We match the two categories of directors with the performance of hiring firms after a director's appointment. Accounting for other contemporaneous effects, we regress the hiring firms' post-performance on director quality and other attributes. The results indicate that directors of “above average” quality are related to hiring firms with “above average” post-performance.
Disaggregated bundle methods for distributed market clearing in power networks

A fast distributed approach is developed for the market clearing with large-scale demand response in electric power networks. In addition to conventional supply bids, demand offers from aggregators serving large numbers of residential smart appliances with different energy constraints are incorporated. Leveraging the Lagrangian relaxation based dual decomposition, the resulting optimization problem is decomposed into separate subproblems, and then solved in a distributed fashion by the market operator and each aggregator aided by the end-user smart meters. A disaggregated bundle method is adapted for solving the dual problem with a separable structure. Compared with the conventional dual update algorithms, the proposed approach exhibits faster convergence speed, which results in reduced communication overhead. Numerical results corroborate the effectiveness of the novel approach.
What is Learned from Longitudinal Studies of Advertising and Youth Drinking and Smoking? A Critical Assessment

This paper assesses the methodology employed in longitudinal studies of advertising and youth drinking and smoking behaviors. These studies often are given a causal interpretation in the psychology and public health literatures. Four issues are examined from the perspective of econometrics. First, specification and validation of empirical models. Second, empirical issues associated with measures of advertising receptivity and exposure. Third, potential endogeneity of receptivity and exposure variables. Fourth, sample selection bias in baseline and follow-up surveys. Longitudinal studies reviewed include 20 studies of youth drinking and 26 studies of youth smoking. Substantial shortcomings are found in the studies, which preclude a causal interpretation.
Indolizinones as synthetic scaffolds: fundamental reactivity and the relay of stereochemical information

Indolizinones are under-explored N-heterocycles that react with exquisite chemo- and stereoselectivity. An exploration of the fundamental reactivity of these azabicycles demonstrates the potential to relay stereochemical information from the ring-fusion to newly formed stereocenters on the bicyclic core. The indolizinone diene undergoes selective hydrogenation and readily participates in Diels–Alder cycloadditions as well as ene reactions. The vinylogous amide embedded in the five-membered ring is resistant to reaction when the diene is in place. However, removal of the diene allows for diastereoselective hydrogenation of, and 1,4-additions to, the vinylogous amide. These fundamental reactions with indolizinones have provided a structurally diverse array of products that hold promise in the context of natural product synthesis.