cssi/SciSciGPT-SciSciNet huggingface dataset:
Reliability Analysis of Power Systems Integrated With High-Penetration of Power Converters

With the growing penetration of power electronic converters in power systems, the issue of reliability becomes more critical than ever before. This paper proposes a hierarchical reliability framework to evaluate the electric power system reliability from the power electronic converter level to the overall system level. On the converter level, the reliability model of a power electronic converter is developed based on the power electronic devices it is composed of, for which various hourly based input profiles and converter topologies are considered. On the system level, reliability metrics such as expected energy not served (EENS) and loss of load expectation (LOLE) are estimated through a non-sequential Monte Carlo simulation. Machine learning regression models, such as support vector regression (SVR), and random forests (RF) are implemented to bridge the nonlinear reliability relationship between two levels. The proposed framework is demonstrated through the modified IEEE Reliability Test System (RTS) 24-bus network. Numerical results show power converter reliability should be considered as an important factor when evaluating overall system reliability performance.
Laser induced graphene for in-situ ballistic impact damage and delamination detection in aramid fiber reinforced composites

Abstract Aramid fiber reinforced polymer composites have been shown to exhibit impressive mechanical properties, including high strength-to-weight ratio, excellent abrasion resistance, and exceptional ballistic performance. For these reasons, aramid composites have been heavily used in high impact loading environments where ballistic properties are vital. In-situ damage monitoring of aramid composites under dynamic loading conditions typically requires externally bonded sensors, which add bulk and are limited by size and space constraints. To overcome these limitations, this work presents a piezoresistive laser induced graphene (LIG) interface for embedded impact sensing in aramid fiber reinforced composites. Through the monitoring of electrical impedance during ballistic impact, information regarding time and severity of the impact is obtained. The impact velocity correlates with the impedance change of the composites, due to delamination between aramid plies and damage to the LIG interface. The delamination length in Mode I specimens also correlates to changes in electrical impedance of the composite. The interlaminar fracture toughness and areal-density-specific V50 of the LIG aramid composites increased relative to untreated aramid composites. This work demonstrates a methodology to form multifunctional aramid-based composites with a LIG interface that provides both improved toughness and imbedded sensing of impact and damage severity during ballistic impact.
Special Issue Introduction: Religion and Material Texts in the Americas

This special issue offers a capacious sample of scholarship on religion and material texts in the Americas, and seeks to reveal the potential of material-texts approaches for the study of religion....
Partition of Interval-Valued Observations Using Regression

Both regression modeling and clustering methodologies have been extensively studied as separate techniques. There has been some activity in using regression-based algorithms to partition a data set into clusters for classical data; we propose one such algorithm to cluster interval-valued data. The new algorithm is based on the k-means algorithm of MacQueen (1967) and the dynamical partitioning method of Diday and Simon (1976), with the partitioning criteria being based on establishing regression models for each sub-cluster. This also depends on distance measures between the underlying regression models for each sub-cluster. Several types of simulated data sets are generated for several different data structures. The proposed k-regressions algorithm consistently out-performs the k-means algorithm. Elbow plots are used to identify the total number of clusters K in the partition. The new method is also applied to real data.
Pseudorandom Generators for Read-Once Monotone Branching Programs

Motivated by the derandomization of space-bounded computation, there has been a long line of work on constructing pseudorandom generators (PRGs) against various forms of read-once branching programs (ROBPs), with a goal of improving the O(log² n) seed length of Nisan’s classic construction [Noam Nisan, 1992] to the optimal O(log n). In this work, we construct an explicit PRG with seed length O(log n) for constant-width ROBPs that are monotone, meaning that the states at each time step can be ordered so that edges with the same labels never cross each other. Equivalently, for each fixed input, the transition functions are a monotone function of the state. This result is complementary to a line of work that gave PRGs with seed length O(log n) for (ordered) permutation ROBPs of constant width [Braverman et al., 2014; Koucký et al., 2011; De, 2011; Thomas Steinke, 2012], since the monotonicity constraint can be seen as the "opposite" of the permutation constraint. Our PRG also works for monotone ROBPs that can read the input bits in any order, which are strictly more powerful than read-once AC⁰. Our PRG achieves better parameters (in terms of the dependence on the depth of the circuit) than the best previous pseudorandom generator for read-once AC⁰, due to Doron, Hatami, and Hoza [Doron et al., 2019]. Our pseudorandom generator construction follows Ajtai and Wigderson’s approach of iterated pseudorandom restrictions [Ajtai and Wigderson, 1989; Gopalan et al., 2012]. We give a randomness-efficient width-reduction process which proves that the branching program simplifies to an O(log n)-junta after only O(log log n) independent applications of the Forbes-Kelley pseudorandom restrictions [Michael A. Forbes and Zander Kelley, 2018].
Assessment of Metrics Between Acceleration Power Spectral Density Metrics and Failure Criteria

Unlike traditional vibration testing that involves driving a single axis, Multi-Input/Multi-Output (MIMO) testing has become increasingly popular due to its ability to more accurately replicate field responses and failure modes. Quantifying the mismatch between test response and field response is critical to understanding whether the field environment was adequately replicated by the vibration test. Ideally, a vibration test would replicate the field response in terms of deflection shape and magnitude and therefore also the stresses in the test article. However, a clear and concise process or metric to quantify the difference with respect to stress between the test and field environment does not exist.
The Dependence of Ancient Greek Geometry and Metaphysics on Craft-Culture

A discussion of Robert Hahn’s The Metaphysics of the Pythagorean Theorem: Thales, Pythagoras, Engineering, Diagrams, and the Construction of the Cosmos out of Right Triangles. Published Online (2021-04-30)Copyright © 2021 by Philip Thibodeau Article PDF Link: https://jps.library.utoronto.ca/index.php/aestimatio/article/view/37624/28620 Corresponding Author: Philip Thibodeau,Brooklyn CollegeE-Mail: pthibodeau@brooklyn.cuny.edu
Reinforcement of Posterior Wall of Aortic Anastomosis

It can be very difficult to expose and control bleeding from the back of an anastomosis after graft is opened and pressurized. The retraction itself can worsen the situation, pulling on the sutures and stretching the needle holes.
Characterization and transcriptional analyses of cDNAs encoding three trypsin‐ and chymotrypsin‐like proteinases in Cry1Ab‐susceptible and Cry1Ab‐resistant strains of sugarcane borer, Diatraea saccharalis

Diatraea saccharalis is a major corn borer pest. Midgut serine proteinases are essential for insect growth and development. Alteration of midgut proteinases is responsible for Bt resistance development in some species. To clone midgut trypsin and chymotrypsin cDNAs and to test if the Cry1Ab resistance in D. saccharalis is associated with changes in midgut proteinases, total midgut tryptic and chymotryptic activities, cDNA sequences, and gene expressions of three trypsin and three chymotrypsin genes were comparatively examined between Cry1Ab-susceptible (Cry1Ab-SS) and Cry1Ab-resistant (Cry1Ab-RR) strains. Full-length cDNAs encoding three trypsin- and three chymotrypsin-like proteinases were sequenced from Cry1Ab-SS and Cry1Ab-RR larvae. These cDNAs code for active forms of midgut serine proteinases with all functional motifs, including signal peptide, conserved His-Asp-Ser for the catalytic triad, three pairs of cysteines for disulfide bridge configurations, and conserved substrate specificity determination residues. In general, cDNA and putative protein sequences are highly similar between Cry1Ab-SS and Cry1Ab-RR strains, except for a few nucleotide and predicted amino acid substitutions, whose function need to be further clarified. Total trypsin and chymotrypsin activities were also similar between Cry1Ab-SS and Cry1Ab-RR strains. Transcriptional levels of the trypsin and chymotrypsin genes had numerical difference between Cry1Ab-SS and Cry1Ab-RR strains, but the difference was not statistically significant. Data suggest that the development of Cry1Ab resistance in D. saccharalis was not significantly associated with these trypsins and chymotrypsins. Results clarified the role of six midgut proteinases and provided a foundation for continuing examination of potential involvement of other midgut proteinases in Bt resistance development and other important biochemical processes.
The Archaea: an Invitation to Evolution†

The discovery of the archaebacteria was serendipitous, but not unexpected. In the late 1960s, the author had begun assembling the program for inferring (organismal) genealogical relationships through rRNA sequence comparisons, as the structure of the universal phylogenetic tree was yet to be determined. Molecular evolution had been on the scene for the better part of a decade, and a universal framework within which to study evolution from the molecules on up was needed. The objective in establishing the phylogenetic program, however, was not to refine bacterial taxonomy per se, but to restore an evolutionary perspective/spirit to biology. This time the focus would be on the evolution of the cell itself, in particular, the evolution of its translation mechanism. The walls of the would-be archaeabacteria were not the most important clue, however, for they would turn out to be nonhomologous among themselves. Not only were the phenotypically diverged cousins of the methanogens beginning to show up, but so were the traits common to all archaebacteria. Though reluctant at first, microbiology did eventually come around to accepting the archaea. Molecular reductionism is now spent as a conceptual force and has settled into being a most useful body of technology. Microbial biology in the meanwhile has undergone a conceptual and methodological revolution of its own, freeing itself from its self-inflicted intellectual confinement. The future of biology lies in microbial ecology. Molecular biology is moving in an evolutionary direction-compelled by its own technology.
Effective Tax Strategies: It's Not Just Minimization

This study examines managerial incentives and practices associated with firms’ tax strategy choices, as well as the relative importance of these factors in determining the primary focus of firms’ tax strategies. Understanding the determinants of firms’ choice of tax strategy is important because the Scholes-Wolfson framework argues that the goal of effective tax planning is to maximize after-tax returns. Therefore, identifying managerial incentives and practices that influence tax strategy choice provides insight into how firms encourage tax planning to improve firm value. I examine two tax strategies: a sustainable tax strategy, which strives to achieve a consistent tax outcome over time, and a minimization tax strategy, which seeks to achieve the lowest possible tax outcome. Controlling for the interdependence of tax strategies, I find that firms are more likely to emphasize a sustainable tax strategy when the CEO’s wealth is more sensitive to changes in the firm’s stock price and less likely to emphasize sustainability when the firm receives more information from its directors’ connections. In contrast, a firm is more likely to concentrate on a minimization tax strategy when the CEO’s wealth is more sensitive to changes in stock return volatility, the firm hires a tax expert audit firm for tax services, or the firm receives more information from its directors’ connections. Finally, I find that managerial incentives are the most important factors for the choice of tax strategy, followed by the practices of obtaining expert tax advice and information from directors’ connections.
Another Look At Theoretical And Em-pirical Issues In Event Study Methodology

The goal of this manuscript is to help to improve the integrity of research that uses event study methodology. We discuss issues related to correctly performing event studies and, in some cases, provide alternatives to a variety of recommendations made by McWilliams and Siegel (1997) regarding the application of event study methodology. While McWilliams and Siegel provide a good starting point for providing guidance in the use of event study methodology, our revised recommendations add additional value beyond McWilliams and Siegel by being more consistent with statistical theory, existing research results, and accepted practice. These recommendations, along with those found in McWilliams and Siegel, should lead to higher quality research, regardless of the discipline to which event study methodology is applied.
Fractional laser-assisted drug delivery: Active filling of laser channels with pressure and vacuum alteration.

Background and Objective Ablative fractional laser (AFXL) is rapidly evolving as one of the foremost techniques for cutaneous drug delivery. While AFXL has effectively improved topical drug-induced clearance rates of actinic keratosis, treatment of basal cell carcinomas (BCCs) has been challenging, potentially due to insufficient drug uptake in deeper skin layers. This study sought to investigate a standardized method to actively fill laser-generated channels by altering pressure, vacuum, and pressure (PVP), enquiring its effect on (i) relative filling of individual laser channels; (ii) cutaneous deposition and delivery kinetics; (iii) biodistribution and diffusion pattern, estimated by mathematical simulation. Methods Franz diffusion chambers (FCs) were used to evaluate the PVP-technique, comparing passive (AFXL) and active (AFXL + PVP) channel filling. A fractional CO2-laser generated superficial (225 µm;17.5 mJ/channel) and deep (1200 µm; 130.5 mJ/channel) channels, and PVP was delivered as a 3-minutes cycle of 1 minute pressure (+1.0 atm), 1 minute vacuum (−1.0 atm), and 1 minute pressure (+1.0 atm). Filling of laser channels was visualized with a colored biomarker liquid (n = 12 FCs, n = 588 channels). Nuclear magnetic resonance quantified intracutaneous deposition of topically applied polyethylene glycol (PEG400) over time (10 minutes, 1 hour, and 4 hours), investigated with (n = 36 FCs) and without (n = 30 FCs) PVP-filling. Two-dimensional mathematical simulation was used to simulate intradermal biodistribution and diffusion at a depth of 1,000 µm. Results Active filling with application of PVP increased the number of filled laser channels. At a depth of 1,000 µm, filling increased from 44% (AFXL) to 94% with one PVP cycle (AFXL + PVP; P < 0.01). Active filling greatly enhanced intracutaneous deposition of PEG400, resulting in a rapid delivery six-folding uptake at 10 minutes (AFXL 54 µg/ml vs. AFXL + PVP 303 µg/ml, P < 0.01). AFXL alone generated an inhomogeneous uptake of PEG400, which greatly improved with active filling, resulting in a uniform uptake within the entire tissue. Conclusion Active filling with PVP secures filling of laser channels and induces a deeper, greater, more rapid delivery than conventional AFXL. This delivery technique has promise to improve treatment efficacy for medical treatments of dermally invasive lesions, such as BCCs. Lasers Surg. Med. © 2015 Wiley Periodicals, Inc.
Estimating the Impact of Scalable Pointer Analysis on Optimization

This paper addresses the following question: Do scalable control-flow-insensitive pointer analyses provide the level of precision required to make them useful in compiler optimizations? We first describe alias frequency, a metric that measures the ability of a pointer analysis to determine that pairs of memory accesses in C programs cannot be aliases. We believe that this kind of information is useful for a variety of optimizations, while remaining independent of a particular optimization. We show that control-flow and context insensitive analyses provide the same answer as the best possible pointer analysis on at least 95% of all statically generated alias queries. In order to understand the potential run-time impact of the remaining 5% queries, we weight the alias queries by dynamic execution counts obtained from profile data. Flow-insensitive pointer analyses are accurate on at least 95% of the weighted alias queries as well. We then examine whether scalable pointer analyses are inaccurate on the remaining 5% alias queries because they are context-insensitive. To this end, we have developed a new context-sensitive pointer analysis that also serves as a general engine for tracing the flow of values in C programs. To our knowledge, it is the first technique for performing context-sensitive analysis with subtyping that scales to millions of lines of code. We find that the new algorithm does not identify fewer aliases than the context-insensitive analysis.
Oral Histories in Meteoritics and Planetary Science––XVI: Grenville Turner

Abstract– In this interview, Grenville Turner (Fig. 1) recounts how he became interested in meteorites during postdoctoral research with John Reynolds at the University of California, Berkeley, after completing a DPhil with Ken Mayne at the University of Oxford. At Berkeley, he worked on xenon isotopes with fellow students Bob Pepin and Craig Merrihue, but Reynolds’ insistence that they analyze all the inert gases in their samples meant that they also made important contributions to Ne isotope studies and potassium-argon dating leading to the Ar-Ar technique. In 1964, Grenville obtained a teaching position at the University of Sheffield where he developed his own laboratory for inert gas isotope measurements. After the return of samples from the Moon by the Apollo program, he became involved in determining the chronology of volcanism and major impacts on the Moon. In 1988, Grenville and his team moved to the University of Manchester as part of a national reorganization of earth science departments. During the post Apollo years, Grenville’s interest turned to the development of new instrumentation (resonance ionization mass spectrometry and the ion microprobe), and to problems in terrestrial isotope geochemistry, particularly the source of inert gases in fluid inclusions. He received the Leonard Medal of the Meteoritical Society in 1999, and he has also received awards from the Royal Society, the European Association of Geochemistry, and the Royal Astronomical Society. Figure 1. Grenville Turner. Download figure to PowerPoint
The delivery of immunizations and other preventive services in private practices.

Objectives . To measure the proportion of children cared for in private pediatric practices who are fully immunized and have been screened for anemia, tuberculosis (TB), and lead poisoning by 2 years of age. Design . Cross-sectional chart review. Setting . Fifteen private pediatric practices in central North Carolina (11 chosen randomly). Patients . One thousand thirty-two randomly selected 2-year-old children. Main Outcome Measures . Proportion of children immunized and screened for anemia, TB, and lead poisoning by 24 months of age and immunization and screening rates of the practices. Results . Sixty-one percent of the children were fully immunized at 24 months of age; the rates among practices varied widely (38% to 82%). Sixty-eight percent of the children had been screened for anemia, 57% had been screened for TB, and 3% had been screened for lead poisoning. Physicians overestimated the proportions of fully immunized children in their practices by an average of 10% (range, -3% to 17%). The median number of well child visits by 2 years of age was 5 (range, 0 to 14), and only 19% of the entire sample made 8 or more well child visits, the number recommended by the American Academy of Pediatrics in the first 18 months of life. The numbers of well child and non-well child visits were the strongest predictors of complete immunization. Practice characteristics associated with being fully immunized included the use of preventive services prompting sheets (eg, flow sheets) in the medical records, not seeing the same physician for all well child care, and having nurses review patients9 immunization status during their visits to the office. Conclusions . Underimmunization and inadequate screening are significant problems in private pediatric practices in North Carolina. Physicians are unaware of the rates of underimmunization in their offices.
Derivation of a formula for the A(d, p)B transition amplitude from the Faddeev equations of three-body scattering theory

I rederive the formula for the $B(p,d)A$ and $A(d,p)B$ transition amplitudes used by Timofeyuk and Johnson [Phys. Rev. C 59, 1545 (1999)] in their study of reactions involving halo nuclei. The method of derivation is to use the coupled equations for the three-body problem in the version of the Faddeev equations reported by Alt, Grassberger, and Sandhas [Nucl. Phys. B2, 167 (1967)].
Maternal Responsiveness: Early Observation of Mothers Who Bottle-Feed Is Needed in Reducing the Risk of Childhood Obesity

Newborn Care Paper Presentation Objective Maternal responsiveness to infant communication or cues to stop or start feeding begins as early as birth. Despite continued efforts to increase the number of mothers who breastfeed their infants to age 6 months, a majority bottle-feed. Because formula-fed infants tend to gain more weight than breastfed infants, mothers who bottle-feed need to be encouraged to allow infants to self-regulate. An infant self-regulates caloric intake by giving hunger and satiety cues. The objective of this study was to measure the association between maternal responses to infant feeding cues and feeding method in 129 lowincome, mother–infant dyads in two Midwestern States.
High resolution multichannel fluorescence detection for capillary electrophoresis. Application to multicomponent analysis

A wavelength-resolved fluorescence detector for laser-induced fluorescence detection in capillary electrophoresis (CE) is described that uses a charge injection device (CID) array detector. Post-column fluorescence detection occurs using a sheath flow cell. The limit of detection for fluorescein is 4.8·10−11 M (29 000 molecules), the spectral resolution is 0.56 nm/pixel, and the spectrograph/CID monitors a 250 nm spectrum throughout the 250–875 nm range. Custom array readout, data manipulation and data processing methods are described to convert wavelength/spatial CID images into electropherograms. The application of the system to characterizing bilirubins in human serum is described, demonstrating the ability to match electrophoretic peaks to standards using spectral information.
Energy Development in the US Rockies: A Role for Counties?

This article analyzes the role played by county commissioners in Colorado and Montana in restricting or facilitating the use of clean energy sources in the generation of electrical power. Using data obtained from responses to an internet survey, we found that many commissioners in both states developed land use policies dealing with renewable energy resources over the preceding five years. Colorado and Montana officials were quite similar in terms of their positive reaction to changes that would facilitate greater county interest in clean energy policies. Most respondents favored increasing the pace of renewable energy use in relation to traditional energy sources but were also supportive of a more inclusive renewable portfolio standard that would embrace clean coal technologies and nuclear power.
Homogeneously Suslin sets in tame mice

This paper studies homogeneously Suslin (hom) sets of reals in tame mice. The following results are established: In 0 ¶ the hom sets are precisely the sets. In M n every hom set is correctly , and ( δ + 1)-universally Baire where δ is the least Woodin. In M ω , every hom set is λ -hom, where λ is the supremum of the Woodins.
EXTRACTING ACCURATE CYCLOTRON MASSES FROM WEAK DE HAAS--VAN ALPHEN BEAT PATTERNS.

Abstract If the presence of the recessive oscillation in a weak de Haas-van Alphen beat pattern is ignored, the apparent value of the cyclotron mass of the dominant oscillation, obtained from the temperature dependence of the amplitude, oscillates in field with the period of the beat. The amplitude of this apparent mass oscillation is large enough to cause significant error if the mass is determined at only one field value. Under the appropriate experimental conditions this error can be eliminated by averaging the apparent mass values obtained at the node and the antinode of the beat pattern.
Analysis of sensitivity of reciprocal matrices

We develop a method based on the Hadamard Product of matrices to analyze the sensitivity of reciprocal matrices. We show that this type of matrices can be decomposed into the Hadamard Product of a consistent matrix and an inconsistent matrix. The consistent matrix has the same principal eigenvector as the original matrix, and the inconsistent matrix has the same principal eigenvalue as the original one. We use this decomposition in the analysis of sensitivity to compute the principle eigenvector of a perturbed reciprocal matrix.
Organic Syntheses by Means of Transition Metal Complexes

I. In t roduct ion . . . . . . . . . . . . . . . . . . . . . 42 II. a-Bond Format ion . . . . . . . . . . . . . . . . . . . 43 1. Oxidative Addi t ion Reactions . . . . . . . . . . . . . 43 2. Reactivity of a-Bonds . . . . . . . . . . . . . . . . 50 3. Oxidative Metal-Metal Bond Cleavage . . . . . . . . . . 54 4. Reactions of Transi t ion Metal Compounds with Organometallic Compounds . . . . . . . . . . . . . . . . . . . . 56 5. Format ion of Metal Carbonylate Anions from Metal Carbonyls and Their Reactions . . . . . . . . . . . . . . . . . 59 III. Insert ion Reactions . . . . . . . . . . . . . . . . . . 64 IV. Liberation of Organic Compounds from the a-Complexes . . . . 70 V. Cyclization Reaction and Related Reactions . . . . . . . . . 74 VI. Concluding Remarks . . . . . . . . . . . . . . . . . . 80 VII. References . . . . . . . . . . . . . . . . . . . . . . 81
Suicide in the United States, 1951–1988: Constant age-period-cohort rates in 40- to 44-year-old men

Age-specific suicide rates in the United States between 1951 and 1988 were shown in cohort, cross-sectional, and age group formats. Despite considerable variation among women and younger and older men, suicide rates among 40- to 44-year-old men have remained stable. Since suicide is strongly influenced by psychosocial stressors, the constant suicide rates in middle-aged men suggest a consistency in the stress experienced by this population subgroup.
Manufacturing of specialty materials in supercritical fluid carbon dioxide

Abstract Supercritical fluid carbon dioxide is used in an industrial manufacturing process, i.e. Ferro Corporation’s SCAMP process, to produce specialty materials such as powder coatings, new polymers, pigments, polymer additives, and a series of temperature sensitive bio materials. The process was verified, on several scales of laboratory equipment, pilot plants and commercial scale all utilizing Ferro’s unique reactor design equipped with proprietary components such as the agitator, mechanical seals, heating/cooling jacket, wall surface, flush valve, cyclonic atomization chamber and its control logic. The products often demonstrated superior dispersion properties and performed equally or better than elevated temperature produced materials. In some cases, the materials so produced possess unique properties, e.g. porosity, particle size distribution, loading, or uniformity, that allow them to be used in new, innovative applications.
Self-selection for stressful experiences

Studies of self-selection for stressful experiences have employed different models advocating variables specific to those models. These investigations typically utilize personal resource or psychological distress measures to predict occurrences of life events and daily hassles. The purpose of this investigation was to combine both types of measures to estimate the occurrence of life events and daily hassles prospectively. Using hierarchical multiple regression, occurrences of stressful experiences were regressed on personal resource variables (mastery, self-esteem, conscientiousness and neuroticism), perceived social support, avoidance coping, gender and psychological distress assessed 10 weeks prior. Results indicated that depressive symptoms and avoidance coping were consistent estimators for both types of stressor. The influence of mastery, self-esteem, neuroticism, social support and gender varied across stressor categories. Copyright © 2010 John Wiley & Sons, Ltd.
Catastrophic isotopic modification of rhyolitic magma at times of caldera subsidence, Yellowstone Plateau Volcanic Field

The Yellowstone Plateau volcanic field has undergone repeated eruption of rhyolitic magma strongly depleted in 18O. Large calderas subsided 2.0, 1.3, and 0.6 Ma ago, on eruption of ash flow sheets that represent at least 2500, 280, and 1000 km3 of zoned magma. More than 60 other rhyolite lavas and tuffs permit reconstruction of the long-term chemical and isotopic evolution of the silicic system. Narrow δ18O ranges in the ash flow sheets contrast with wide δ18O variations in postcaldera lavas of the first and third caldera cycles. Earliest postcollapse lavas are 3 to 6‰ lighter than the preceding ash flow sheets. The O18 depletions were short-lived events that immediately followed caldera subsidence; hundreds of cubic kilometers of magma were drastically 18O depleted and thousands were depleted by 1–2‰. Sequences of postcaldera lavas record partial recovery toward precaldera δ18O values; secular trends between collapse events thus reflect gradual reenrichment of the roofmost magma in δ18O. Much of the subcaldera reservoir was affected, because lavas that erupted as far apart as 115 km reflect the same pattern of depletion and partial recovery. Contemporaneous extracaldera rhyolites have the highest δ18O values in the volcanic field and show no effects of the repeated depletions. Sr and Pb isotope ratios of intracaldera rhyolites jump to more radiogenic values at times of caldera formation and show a longterm zigzag pattern like that of δ18O. Although some contamination by foundering roof rocks seenis to be required, water was probably the predominant contaminant. Even if roof rocks had been strongly depleted in O18 before engulfment, their assimilation would have been far from sufficient to account for the large O18 shift. The low- O18 lavas contain no xenocrysts and show no trace element or phenocryst evidence of massive contamination. Their Fe-Ti-oxide temperatures indicate no cooling relative to the caldera-forming ash flow magma, and their whole-rock, glass, and phenoeryst chemistry suggests compositional continuity with the ash flow sequence. Oxygen exchange between the magma and a mass of low-O18 water greatly exceeding solubility limits may require (1) recurrent explosive activity to sustain access and mixing of water with the magma and (2) convection of the magma reservoir to prevent local saturation.
Perioperative measurements of interleukin-6 and α-melanocyte-stimulating hormone in cardiac transplant patients

Abstract Interleukin-6 (IL-6) and α-melanocyte-stimulating hormone (αMSH) are important modulators of the immunologic response to tissue injury and antigenic challenge. Serial changes in the plasma concentrations of these two peptides were measured in 12 patients undergoing heart transplantation. Tissue concentrations of IL-6 in atrial samples from both donor and recipient hearts were also compared. Plasma IL-6 concentration remained stable prior to cardiopulmonary bypass (CPB), initially decreased with the onset of CPB, and then increased significantly over control values at the end of CPB (180 ± 40 v 53 ± 60 pg/mL). Plasma IL-6 remained elevated for at least 60 minutes after CPB, and then it returned to control values by 24 hours postoperatively (67 ± 9 pg/mL). Examination of IL-6 changes after CPB in 10 additional patients undergoing nontransplant cardiac surgery with CPB revealed a similar elevation in IL-6 at 60 minutes after CPB (290 ± 76 pg/mL). However, IL-6 in the nontransplant group remained significantly elevated at 24 hours (138 ± 42 pg/mL). These combined results suggest that CPB causes a marked increase in IL-6, and that implantation of a new heart in transplant patients does not augment this increase. The return of IL-6 to control values by 24 hours in the patients who have had transplants suggests that immunosuppression has an appreciable effect on IL-6 at this time. In contrast to IL-6, plasma αMSH never increased above control values. The absence of a significant change in αMSH suggests that there is no interaction between these two immunologic modulators under the conditions of this study. Tissue IL-6 in hearts with idiopathic cardiomyopathy was significantly less than that in other hearts (ie, donor hearts and hearts with ischemic cardiomyopathy). Additional studies are required to determine if this reduced tissue concentration of IL-6 is related to the cardiomyopathic process.
Numerical range of a matrix: some effective criteria

Abstract Algorithms are presented which decide, for a given complex number w and a given complex n × n matrix S , whether w is in the numerical range W ( S ) of S , whether w is a boundary point of W ( S ), whether w is an extreme point of W ( S ), whether w is a bare point of W ( S ), and whether w is a vertex of W ( S ). Further algorithms decide whether W ( S ) intersects a given line (or a given ray), whether W ( S ) is included in a given open half plane (or a given closed half plane), and, for a given real number r , whether the numerical radius ρ s of S is > r , whether ρ s = r , and whether ρ s ≥ r . A simple effective criterion for H -stability is also given: a nonsingular H -semistable matrix S is H -stable iff the nullity of ( S + S ∗ ) S -1 ( S + S ∗ ) is twice the nullity of S + S ∗ . The computations involved in all these algorithms are elementary (rational operations, the max operation on pairs of real numbers, the degree of a nonzero polynomial, and the number of sign variations in the coefficients of a nonzero real polynomial), must be carried out exactly, and give exact (i.e., 100% reliable) results. Examples are worked out to illustrate the application of some of the algorithms.
Neutral compounds from male castoreum of North American beaver,Castor canadensis.

North American beavers (Castor canadensis) mark their territories with castoreum, the strong-smelling paste in their castor sacs. In their own territories, beavers respond with scent marking to experimental scent marks that consist of strange castoreum (or selected components). In part, the unique odor of castoreum is due to large amounts of phenolic compounds and neutral compounds. Purified neutral compounds were analyzed by GC. GC-MS, and NMR; identities of the neutral compounds were confirmed by comparing the properties of authentic compounds with those of the isolated compounds. We identified 13 neutral compounds that had not been reported before for castoreum. Most of these are oxygen-containing monoterpenes. Of the nine neutral compounds reported by Lederer (1949), only three are confirmed in our analysis; the other six neutral compounds are either absent or are not volatile enough to be detected by our methods. Eight compounds—6-methyl-l-heptanol, 4,6-dimethyl-l-heptanol, isopinocamphone, pinocamphone, two linalool oxides, and their acetates—were synthesized for structure identification and bioassays.
An Evaluation of Private Club Members' Desires in Price, Food Quality and Level of Service

Abstract The impact of price, food quality and level of service on the purchase decisions by private club members was investigated to determine the effect of these factors and the trade-off by members among these variables. A conjoint analysis was used to examine the subjects' utilities for lunch alternatives that differed in the factors. The effect on a subjects' utilities was studied in relation to the importance of the dining situation (i.e., high or low importance depending on the reason for dining at the club). The results indicated that pricing, level of food quality and service are important to private club members and that their importance varies with the purchasing situation. For example, club members are more price sensitive in a less important dining situation, such as a typical lunch with other club members, but are less price conscious and more concerned about the quality of the food and service in more important situations, such as business meetings.
Characterization of gas pipeline inspection signals using wavelet basis function neural networks

Magnetic flux leakage techniques are used extensively to detect and characterize defects in natural gas transmission pipelines. This paper presents a novel approach for training a multiresolution, hierarchical wavelet basis function (WBF) neural network for the three-dimensional characterization of defects from magnetic flux leakage signals. Gaussian radial basis functions and Mexican hat wavelet frames are used as scaling functions and wavelets respectively. The centers of the basis functions are calculated using a dyadic expansion scheme and a k-means clustering algorithm. The results indicate that significant advantages over other neural network based defect characterization schemes could be obtained, in that the accuracy of the predicted defect profile can be controlled by the resolution of the network. The feasibility of employing a WBF neural network is demonstrated by predicting defect profiles from both simulation data and experimental magnetic flux leakage signals.
Case for Changing Reinforcing Bar Deformation Spacing Requirements

The bond strength of four sets of reinforcing bars is evaluated, two each with No. 5 and No. 10 (No. 16 and No. 32) bars, which have, respectively, nominal diameters of 0.625 and 1.27 in. (15.9 and 32.3 mm). One bar of each size satisfies the criterion for maximum deformation spacing in ASTM reinforcing bar specifications, while the other has deformations that exceed the maximum spacing. All bars exceed the requirements for minimum deformation height. Research related to the effect of deformation properties on bond strength, including the research used to establish the requirements for deformations in ASTM reinforcing bar specifications, is also reviewed. The test results match earlier research and demonstrate that (1) bond strength is not governed by the specific value of deformation height or spacing, but by the combination of the two as represented by the relative rib area of the bars and (2) the bond strength of the bars with deformation spacings that exceed those in ASTM reinforcing bar specifications is similar to the bond strength of the bars that meet the specification. Based on this and prior research, it is recommended that ASTM reinforcing bar specifications be modified to allow for deformation spacing up to 90 % (currently a maximum of 70 %) of the bar diameter provided the ratio of deformation height to deformation spacing is greater than or equal to the minimum ratio for bar deformations meeting the current requirements in ASTM reinforcing bar specifications.
A Nouveau Aid for Posture Training in Degenerative Disorders of the Central Nervous System

Objective: The study was conducted to facilitate erect posturing in patients with neurodegenerative disorders through use of the Posture Training Support [PTS]. Methods: PTS was applied posteriorlyin subjects with a tendency to lean forward and anteriorly in patients with a tendency to fall backward. The subjects were then questioned on long-term follow-up to determine whether they were still using the PTS and whether they found it helpful in terms of gait and activities of daily living [ADLs]. Results: All of the patients, except for one, reported an improvement in gait and ADLs. Conclusions: The PTS may help improve gait and ADLs in patients with certain neurodegenerative disorders.
Content Management and the Separation of Presentation and Content

The importance of separating presentation from content is taken as a given in many kinds of publishing, despite the fact that the notion of separation has received little critical scrutiny. I provide a closer look at the separation, first by providing contemporary and historical context, then by laying out key distinctions in the ways the separation argument is used in Web design versus Web content management versus full-featured content management systems (CMSs). I suggest that these distinctions are critical in how we should view the separation and the implications of the separation for the work of technical communicators.
Effect of director fluctuations on the nematic distribution function

Abstract The effect of director fluctuations on the nematic distribution function is calculated. It is shown that depending on the value of a dimensionless material parameter γ, director fluctuations can significantly influence the observed values of the order parameter.
Morphology of Polyethylene-Carbon Black Composites

Carbon black is a common polymer additive that is used for reinforcement and for its ability to enhance physical properties, such as conductivity. This article pertains to an X-ray scattering (SAXS) study of a conductive grade of carbon black and carbon black-polymer composites. The scattering pattern for such blacks displays a surface-fractal-like power-law decay over many decades in scattering vector q .I t is often assumed that small-angle scattering from carbon black aggregates can be de- scribed in terms of surface-fractal models, related to particles with fractally rough surfaces. Such self-similar surface roughness is usually easy to identify by microscopy; however, electron microscopy from these blacks fails to support this assumption. It is proposed here that this apparent surface-fractal scattering actually represents a more complicated morphology, including overlapping structural features and a power-law scaling of polydispersity. One use of conductive black-polyethylene composites is in circuit protection devices where resistive heating leads to a reversible association of carbon black aggregates that controls switching between a conductive and a noncon- ductive state. Scattering can be used as an in situ tool to observe the morphological signature of this reversible structural change. Scattering patterns support a model for this switching based on local enhancement of concentration and the formation of linear agglomerates associated with the matrix polymer's semicrystalline morphology. © 1999
Guest Editors' Introduction: Information Discovery--Needles and Haystacks

For thousands of years, people have realized the importance of archiving and finding information. With the advent of computers, it became possible to store large amounts of information in electronic form -- and finding useful needles in the resulting haystacks has since become one of the most important problems in information management.
Structural and magnetic properties of the Y1-xThxFe3 and Lu1-xThxFe3 systems*

Abstract The structural and magnetic properties of the pseudobinary Y 1− x Th x Fe 3 and Lu 1− x Th x Fe 3 systems, having the PuNi 3 structure, have been investigated. For x ≤0·3, the magnetization vs temperature behavior for both systems is consistent with a simple ferromagnetic iron sublattice. For x >0·3, both systems show anomalies in M vs T and M vs H data. Lattice constants for both systems show a monotonic increase with increasing thorium content. The anomalous magnetic behavior has been explained by a Friedel-oscillation mechanism.
Analysis of eyepoint locations and accuracy of rendered depth in binocular head-mounted displays

Accuracy of rendered depth in virtual environments includes the correct specification of the eyepoints from which a stereoscopic pair of images is rendered. Rendered depth errors should be minimized for any virtual environment. It is however critical if perception is the object of study in such environments, or augmented reality environments are created where virtual objects must be registered with their real counterparts. Based on fundamental optical principles, the center of the entrance pupil is the eyepoint location that minimizes rendered depth errors over the entire field of view if eyetracking is enable. Because binocular head mounted displays (HMDs) have typically no eyetracking capability, the change in eyepoints location associate with eye vergence in HMDs is not accounted for. To predict the types and the magnitude of rendered depth errors that thus result, we conducted a theoretical investigation of rendered depth errors linked to natural eye movements in virtual environments for three possible eyepoints locations: the center of the entrance pupil, the nodal point, and the center of rotation of the eye. Results show that, while the center of rotation yields minimal rendered depth errors at the gaze point, it also yields rendered angular errors around the gaze point, not previously reported.
A Comparison of Methods for Determining Tropopause Height from VHF Radar Observations

Abstract Four methods of estimating the height of the tropopause with VHF radar are compared and evaluated using data from a wind-profiling radar located at Platteville, Colorado, approximately 50 km north of Denver. An empirically derived method determines the tropopause height from the strength and persistence of the reflections. A second, theoretically based, method uses Fresnel scattering model estimates of the temperature gradient to determine the tropopause height. A third method identifies specular reflections associated with the tropopause by comparing vertical with oblique reflections. The final method combines the theoretically based method with a consensus set method for determining the most consistent estimates. The methods are compared by taking differences between the estimates and the tropopause heights determined from radiosonde data using the WMO definition of the tropopause. Each method is evaluated by calculating rms differences from the radiosonde determinations and by the number of di...
Basic computer program for amino acid analysis data.

Abstract A computer program for the reduction of output data from automatic amino acid analyzers has been written using the Beginners all Purpose Symbolic Instruction Code (BASIC) language. From input data consisting of integrator peak areas and sample weight and volume the program calculates μmoles of amino acids present in the run, total μmoles amino acids in the sample, minimal molecular weight, residue number composition, μmoles amino acid per milligram sample, grams amino acid per 100 g sample (% yield), and grams amino acid per 100 g protein.