cssi/SciSciGPT-SciSciNet huggingface dataset:
The Future of Differential Equations

ACCORDING TO an old Danish proverb, it is difficult to predict, especially the future. That does not discourage requests for predictions; in this new millennium the demand is ever more pressing. The authors of this volume, in honor of Nick Metropolis, have been asked to foretell the future of their fields. We’ll comply the best we can, viewing the recent past as a clue.
Poverty and the Role of Public Transportation

This paper, published in 2008 and featured in the Journal of Urban Economics, was authored by Edward Glaeser, Matthew Kahn, and Jordan Rappaport and investigates the influence of access to public transportation on the urbanization of poverty. The authors sought to explain why the poor tend to populate dense cities within metropolitan areas versus the surrounding suburbs. Through the use of statistical regression and selected data from surveys and censuses the authors were able to prove with statistical significance that, while not the only factor, access to public transportation is the primary reason for central city poverty. The goal of the research was to develop a theory of urban centralization that should explain the separation of the poor and non-poor, and why given this relationship the poor choose to live in the center of cities.
Future Civil Aircraft and Technologies

New aircraft technologies are presented that have the potential to expand the air transportation system and reduce congestion through new operating capabilities while also providing greater levels of safety and environmental compatibility. These new capabilities will result from current and planned civil aeronautics technology at the NASA Ames, Lewis, and Langley Research Centers and will cover the complete spectrum of current aircraft and new vehicle concepts including rotorcraft (helicopters and tilt rotors), vertical and short takeoff and landing (V/STOL), and short takeoff and landing (STOL) aircraft, subsonic transports, high-speed transports, and hypersonic/transatmospheric vehicles. New technologies will improve efficiency, affordability, safety, and environmental compatibility of current aircraft and will enable the development of new transportation system. The new capabilities of vehicles could lead to substantial market opportunities and economic growth and could improve the competitive position of the U.S. aerospace industry.
Racism, History of

Initially viewed by historians as a theory of difference, racism is now usually seen as an ideology with an integral relationship to domination or exclusion. The most conspicuous forms of modern racism—white supremacy and antisemitism—have been studied separately. A general or comparative history could be based on a definition of racism as an ideology sanctioning the domination or exclusion of one ethnic group by another on the basis of difference believed to be hereditary and unalterable. Racism can, thus, be distinguished from xenophobia and religious intolerance. It emerges in the late medieval and early modern periods in conceptions of Jewishness as ancestry rather than belief and of blackness as a curse condemning Africans to servitude. The scientific revolution and the Enlightenment provided foundations for naturalistic racism. The struggle over slavery and the accelerated expansion of Europe into Africa and Asia brought color-coded racism to full consciousness in the nineteenth century. European antisemitic racism emerged in the context of modernity and the emancipation of the Jews. Racism climaxed during the twentieth century in the segregation of blacks in the American South and in South Africa and in the genocidal assault on European Jewry.
Exploring Python as a learning and teaching language

Since adopting Python for our first two computer science courses we have come to appreciate its simplicity and power. We have also seen Python creep into other courses in our curriculum because it makes the presentation of concepts so easy and clear. In this workshop, participants will explore the Python programming language and consider ways that it can be used to facilitate the understanding of typical introductory computer science concepts. After a brief introduction to the Python essentials, we will implement a number of examples ranging from graphics and image processing to data structures, recursion, threading, and network programming. Participants will leave the workshop with an understanding of the basic features of Python as well as an appreciation for the ease and clarity it can bring to the problem solving process.
Staple food control and industrial development in postwar Japan, 1950–1957: The role of the black market

Abstract Japanese rice policy in the early postwar period consisted of a compulsory delivery and rationing system designed to transfer economic surplus from farmers to urban workers to relieve upward pressure on industrial wage rates. The system was not consistent with private incentives so a black market in rice about half the size of the official market existed. This paper uses simple welfare analysis to estimate the magnitudes of the transfers and social costs involved for 1950–1957. The analysis suggests that the black market played an important role in the success of the rice policy during this period and provides a rationale for the apparent willingness of Japanese authorities to allow the black market to function alongside the official market.
International Equity and Differentiation in Global Warming Policy

ne of the major obstacles to reaching a comprehensive agreement on global warming is the setting of greenhouse gas emission reduction targets for individual countries. Long-standing tensions between industrialized and developing countries have raised the issue of equity in burden-sharing. Moreover, individual industrialized nations have pleaded special circumstances and have sought differentiation in their obligations. This paper analyzes alternative rules for distributing tradable carbon dioxide emissions permits. A non-linear programming model, which distinguishes between allocation-based and outcome-based rules, is used to analyze the relative welfare outcomes. The model is applied to the world body of nations and yields several important policy implications.
B-SPLINE CURVES AND SURFACES

Publisher Summary An example of a highly successful computerized design system is Systeme UNISURF, which was developed by P.Bezier at Regie Renault. The essence of the success of Bezier's system is that it combines modern approximation theory and geometry in a way that provides the designer with computerized analogs of his conventional design and drafting tools. The computational aspects of computing with B-splines have been considered by deBoor and Cox, who independently developed an algorithm that overcomes the problems of numerical instability based upon straightforward calculations of alternate definitions of B-splines. This chapter presents the use of this algorithm for various computations and also describes the procedure for evaluating B-spline functions.
Input distance and lower bounds for propositional resolution proof length

Input Distance (Δ) is introduced as a metric for propositional resolution derivations. If $\mathcal{F} = C_i$ is a formula and D is a clause, then $\Delta(\mathcal{D},\mathcal{F})$ is defined as mini |D – Ci|. The Δ for a derivation is the maximum Δ of any clause in the derivation. Input Distance provides a refinement of the clause-width metric analyzed by Ben-Sasson and Wigderson (JACM 2001) in that it applies to families whose clause width grows, such as pigeon-hole formulas. They showed two upper bounds on $(W - width(\mathcal{F}))$, where W is the maximum clause width of a narrowest refutation of $\mathcal{F}$. It is shown here that (1) both bounds apply with $(W - width(\mathcal{F}))$ replaced by Δ; (2) for pigeon-hole formulas PHP(m, n), the minimum Δ for any refutation is Ω(n). A similar result is conjectured for the GT(n) family analyzed by Bonet and Galesi (FOCS 1999).
Fast Computation of Discrete Logarithms in GF (q)

The Merkte-Adleman algorithm computes discrete logarithms in GF (q),the finite field with q elements, in subexponential time, when q is a prime number p. This paper shows that similar asymptotic behavior can be obtained for the logarithm problem when q = p m , in the case that m grows with p fixed. A method of partial precomputation, applicable to either problem, is also presented. The precomputation is particularly useful when many logarithms need to be computed for fixed values of p and m.
Airflow pressure and shear forces on a rotating, deformed disk in an open shroud

Abstract The static pressure and surface shear forces on a rotating, umbrella-deformed disk in an open shroud are investigated numerically to develop a proper dynamical model for investigation of the self-excited vibration of the disk. The fluid force distributions along the radial direction of the rotating disk are obtained by use of a two-dimensional numerical model of the axisymmetric deformation of disk. It is observed that the effects of Reynolds number and deformation amplitude are very significant on the fluid forces. Once the rotating disk is deformed, the vortex asymmetry in the airflow patterns appears in the narrow and wide gaps between the rotating disk and the two fixed walls. With increasing deformation amplitude, the asymmetry becomes more obvious. The vortex becomes strong as Reynolds number increases. In addition, it is observed that the transition flow between the laminar and turbulent flows exists in the narrow-gap side. Such a transition flow causes the fluid forces to be non-smooth in the corresponding region, and the force discontinuity will lead to the complicated vibration of rotating disk. From this investigation, the fluid forces for different modes of the rotating disk should be further investigated analytically and numerically for a better understanding of the mechanism of self-excited vibration in hard-disk drive system.
Role of MAPK in cerebral vasospasm.

Cerebral vasospasm is the major cause of mortality and morbidity in patients of subarachnoid hemorrhage. Despite intensive studies during the past five decades, the signaling pathways in cerebral arteries that lead to the pathological contraction remain elusive. The complex nature of cerebral vasospasm requires a complex signaling pathway or a group of pathways that may need to interact to initiate and maintain vasospasm. This review explores the possibility that mitogen-activated protein kinase is the elusive signaling pathway responsible for cerebral vasospasm.
Asymptotic freedom in solids - A theorem

A cusp theorem is proved that relates the zero-separation value and slope of two-particle position correlation functions in quantum many-body systems with Coulombic interactions. The theorem is independent of the particle type and symmetry of the wave function. Its proof uses only the integral form of the Schroedinger equation and the continuity and exponential decay of the wave function. It is used to derive a sum rule for the electron-gas structure factor and an exact statement about the screening of point charges. Applications to atomic-orbital-based calculations for H2 and metallic H are described.
Mass spectra of organometallic compounds—VII; Organonitrogen derivatives of metal carbonyls†

The positive-ion mass spectra of the following organonitrogen derivatives of metal carbonyls are discussed: (i) The compounds NC5H4CH2Fe(CO)2C5H5, NC5H4CH2COMo(CO)2C5H5, NC5H4CH2W(CO)3C5H5, NC5H4CH2COMn(CO)4, C5H10NCH2CH2Fe(CO)2C5H5, (CH3)2NCH2CH2COFeCOC5H5 and (CH3)2NCH2CH2COMn(CO)4 obtained from metal carbonyl anions and haloalkylamines, (ii) The isocyanate derivative C5H5Mo(CO)3CH2NCO; (iii) The arylazomolybdenum derivatives RN2Mo(CO)2C5H5 (R phenyl, p-tolyl, or p-anisyl); (iv) The compound (C6H5N)2COFe2(CO)6 obtained from Fe3(CO)12 and phenyl isocyanate; (v) The N,N,N′,N′-tetramethylethylenediamine complex (CH3)2NCH2CH2N(CH3)2W(CO)4. Further examples of eliminations of hydrogen, CO, and C2H2 fragments were noted. In addition evidence for the following more unusual processes was obtained: (i) Elimination of HCN fragments from the ions [NC5H4CH2MC5H5]+ to give the ions [(C5H5)2M]+ (M Fe, Mo and W); (ii) Conversion of C5H5Mo(CO)3CH2NCO to C5H5Mo(CO)2CH2NCO within the mass spectrometer; (iii) Elimination of N2 from [RN2MoC5H5]+ to give [RMoC5H5]+; (iv) Novel eliminations of HNCO, FeNCO, and C6H5NC fragments in the mass spectrum of (C6H5N)2COFe2(CO)6; (v) Facile dehydrogenation of the N,N,N′,-N′-tetramethylethylenediamine ligand in the complex (CH3)2NCH2CH2N(CH3)2W(CO)4.
Effects of Inhibitory Feedback in a Network Model of Avian Brain Stem

The avian auditory brain stem consists of a network of specialized nuclei, including nucleus laminaris (NL) and superior olivary nucleus (SON). NL cells show sensitivity to interaural time difference (ITD), a critical cue that underlies spatial hearing. SON cells provide inhibitory feedback to the rest of the network. Empirical data suggest that feedback inhibition from SON could increase the ITD sensitivity of NL across sound level. Using a bilateral network model, we assess the effects of SON feedback inhibition. Individual cells are specified as modified leaky-integrate-and-fire neurons with time constants and thresholds that vary with inhibitory input. Acoustic sound level is reflected in the discharge rates of the model auditory-nerve fibers, which innervate the network. Simulations show that with SON inhibitory feedback, ITD sensitivity is maintained in model NL cells over a threefold range in auditory-nerve discharge rate. In contrast, without SON feedback inhibition, ITD sensitivity is significantly reduced as input rates are increased. Feedback inhibition is most beneficial in maintaining ITD sensitivity at high-input rates (simulating high sound levels). With SON inhibition, ITD sensitivity is maintained for both interaurally balanced inputs (simulating an on-center sound source) and interaurally imbalanced inputs (simulating a lateralized source). Further, the empirically observed temporal build-up of SON inhibition and the presence of reciprocal inhibitory connections between the ipsi- and contralateral SON both improve ITD sensitivity. In sum, our network model shows that inhibitory feedback can substantially increase the sensitivity and dynamic range of ITD coding in the avian auditory brain stem.
Spiroguanidine rhodamines as fluorogenic probes for lysophosphatidic acid

Direct determination of total lysophosphatidic acid (LPA) was accomplished using newly developed spiroguanidines derived from rhodamine B as universal fluorogenic probes. Optimum conditions for the quantitative analysis of total LPA were investigated. The linear range for the determination of total LPA is up to 5 μM with a limit of detection of 0.512 μM.
The Regional Influence of an Intense Sierra Barrier Jet and Landfalling Atmospheric River on Orographic Precipitation in Northern California: A Case Study

AbstractA 915-MHz wind profiler, a GPS receiver, and surface meteorological sites in and near California’s northern Central Valley (CV) provide the observational anchor for a case study on 23–25 October 2010. The study highlights key orographic influences on precipitation distributions and intensities across northern California during a landfalling atmospheric river (AR) and an associated Sierra barrier jet (SBJ). A detailed wind profiler/GPS analysis documents an intense AR overriding a shallow SBJ at ~750 m MSL, resulting in record early season precipitation. The SBJ diverts shallow, pre-cold-frontal, incoming water vapor within the AR poleward from the San Francisco Bay gap to the northern CV. The SBJ ultimately decays following the passage of the AR and trailing polar cold front aloft. A statistical analysis of orographic forcing reveals that both the AR and SBJ are crucial factors in determining the amount and spatial distribution of precipitation in the northern Sierra Nevada and in the Shasta–Trini...
Trustworthy vacuuming and litigation holds in long-term high-integrity records retention

Relational databases are periodically vacuumed to remove tuples that have expired. During the discovery phase of litigation, plaintiffs ask defendants for access to information related to their case. The requested information is then subject to a litigation hold, which means that the information cannot be deleted. Vacuuming exposes a database to a new threat -- adversaries can try to thwart database auditing mechanism by masquerading an illegal tuple deletion as a vacuuming operation, and delete an unexpired tuple, or a tuple under a litigation hold.In this paper, we provide a generic framework for auditing vacuuming, augment existing database integrity audit mechanisms to support vacuuming, formalize the notion of a litigation hold, and identify key issues in the context of database systems for long-term, high-integrity records retention. Then, we propose several schemes for efficiently implementing trustworthy litigation holds. Finally, we evaluate the efficiency and tradeoffs of the different schemes using a series of experiments.
Evaluation of Renal Transplant Dysfunction by Duplex Doppler Sonography: A Prospective Study and Review of the Literature

A disconcertingly wide variation exists in the literature as to the accuracy of duplex Doppler sonography in the detection of acute renal transplant rejection. Sensitivities range from 9% to 76%. In an attempt to explain the disparity of results, we undertook a double-blind prospective study of the accuracy of duplex Doppler ultrasound in the detection of acute rejection in renal transplants. We scanned 49 consecutive patients with a total of 65 biopsies; 46 biopsies in 33 consecutive patients were included in our study. In our population, the prevalence of acute rejection was 61% (28/46). Using a resistive index (RI) cutoff of greater than 0.90 based on the main renal artery flow pattern, the sensitivity of our test was 43%, with a 67% specificity. The positive predictive value was 67%. Our results are contrasted and compared with the published data from other groups in a critical survey of the literature. We conclude that duplex Doppler sonography alone is inadequate to evaluate acute rejection in renal transplants.
Evaluating dynamic efficiency by optimal control

Some control-theoretic methods for evaluating the efficiency of production units in dynamic situations are developed and empirically illustrated on the basis of adjustment cost theory.
A modified Ortega method to evaluate the activation energies of solid state reactions

The application of the average linear integral isoconversional method developed by Ortega for evaluating the activation energies of solid state reactions may be hindered by experimental noise and the uncertainties associated with selecting appropriate reaction segments. This paper suggests a procedure, called the modified Ortega method, which can avoid or minimize these hindrances. By applying the modified Ortega method to the kinetic analyses of both simulated and experimental data, a more consistent dependence of the activation energy on the extent of reaction conversion was found with those calculated from the modified Vyazovkin method and the Friedman method.
Complementary GaAs (CGaAs™): New enhancements

Abstract Performance improvements in complementary GaAs circuits require further device improvements. Evolutionary device improvements were made in the areas of threshold voltage, submicron gates, and gate leakage. The threshold voltage of n -channel devices were de˜coupled from p -channel devices by setting a low threshold for the NFET (0.3 V) through epitaxial design and ion implantation in the PFET active channel for reduced PFET threshold voltage. Subthreshold leakage currents were controlled for submicron and deep submicron devices through use of low temperature buffer layers and optimization of implant schedule, RTA temperature and epi/buffer contamination. As a result, 0.3 × 10 micron PFETs of good IV characteristics were realized for the first time. Transconductance was 88 mS/mm and subthreshold leakage as low as 26 nA was achieved at V ds = −1.5V·PISCES two dimensional device simulations showed optimized submicron PFETs of 0.35 micron gate lengths should yield F t of 17 GHz.
Post-world war II treaty research sources, finding tools, and status information sources

Abstract Since World War II, the number of treaties and the subjects those treaties touch upon have steadily increased. As a result, many researchers need to locate treaty texts and determine a treaty's status. This bibliographical essay describes treaty sources, finding tools, and status information sources for treaties concluded since World War II. The publications of international organizations, national governments, and commercial publishers are described.
Ethnic and gender differences among opiate addicts.

This study compares the clinical characteristics of and treatment implications for five demographic groups of addicts: Black and White males and females and Hispanic males evaluated in Spanish. Amo...
Evidence for the separate regulation of the human papillomavirus type 11 E7 and E6 promoters by Viral cis sequences near the E6 promoter.

Abstract The human papillomavirus type 11 (HPV-11) E7 protein can modulate host cell functions and is required for papilloma formation, but little is known concerning the regulation of its expression. This study was designed to determine whether the viral upstream regulatory region controlled expression from the E7 promoter and whethercissequences differentially regulated E6 and E7 expression in laryngeal mucosal keratinocytes, the natural target cells for this virus. Reporter constructs were designed to study expression of the luciferase gene from the HPV-11 E7 promoter in its natural position downstream of a functional E6 promoter. E7 expression, like E6 expression, required upstream regulatory sequences. However, E7 expression was less sensitive to repression by viral E2 protein and to mutation of the SpI binding site adjacent to the E2 binding site. Moreover, there was differential sensitivity of the two promoters to mutation of the E6 TATA box, with E7 expression more affected than E6 expression. These findings show that, in the normal host cells for this virus, the E6 and E7 promoters can be independently regulated by thecisregulatory region adjacent to the E6 promoter.
SOCIAL CLASS DIFFERENCES IN THE ABILITY OF YOUNG CHILDREN TO USE VERBAL INFORMATION TO FACILITATE LEARNING

Two-year-old white boys from Low and High social class (SES) groups were presented with identical learning tasks under nonverbal and verbal conditions. Under the nonverbal condition there were no SES differences, but under the verbal condition the High SES subjects significantly improved their performance and were superior to the Low SES subjects.
Nocturnal drainage flow on simple slopes

Observations of nocturnal slope flow have been made at two sites with quite different topography and vegetation. In both cases, continuous measurements of wind and temperature profiles were made from towers that extended through the depth of the katabatic flow. At the simpler site, which approximates a tilted plane, three towers were located at different distances down the slope to measure the development of slope flow with downslope distance. Slope flow depth, downslope wind speed, and temperature deficit are found to change with downslope distance at rates that are consistent with the predictions of Manins and Sawford's (1979) layer-averaged model of slope flow, while measured entrainment rates are found to be comparable to those predicted by Ellison and Turner's (1959) laboratory experiments. The depth of slope flow is found to be roughly 0.05 times the vertical drop from the top of the slope, a relationship that also follows from combining Manins and Sawford's model and Ellison and Turner's laboratory data. Analysis of the wind spectra and a simple numerical model suggest that the turbulent kinetic energy profiles in slope flow are dependent on the speed and direction of the ambient wind and can differ substantially from those found over flat terrain. At the more complex of the two measurement sites, the occurrence of slope flow was found to correlate well with a dimensionless number 5 that is a function of the ridge-top wind speed and of the strength and depth of the inversion and that is an estimate of the ratio of the buoyancy deficit to the external horizontal pressure gradient.
Characterization of the interaction between the Wilson and Menkes disease proteins and the cytoplasmic copper chaperone, HAH1p.

Wilson disease (WD) and Menkes disease (MNK) are inherited disorders of copper metabolism. The genes that mutate to give rise to these disorders encode highly homologous copper transporting ATPases. We use yeast and mammalian two-hybrid systems, along with anin vitro assay to demonstrate a specific, copper-dependent interaction between the six metal-binding domains of the WD and MNK ATPases and the cytoplasmic copper chaperone HAH1. We demonstrate that several metal-binding domains interact independently or in combination with HAH1p, although notably domains five and six of WDp do not. Alteration of either the Met or Thr residue of the HAH1p MTCXXC motif has no observable effect on the copper-dependent interaction, whereas alteration of either of the two Cys residues abolishes the interaction. Mutation of any one of the HAH1p C-terminal Lys residues (Lys56, Lys57, or Lys60) to Gly does not affect the interaction, although deletion of the 15 C-terminal residues abolishes the interaction. We show that apo-HAH1p can bind in vitroto copper-loaded WDp, suggesting reversibility of copper transfer from HAH1p to WD/MNKp. The in vitro HAH1/WDp interaction is metalospecific; HAH1 preincubated with Cu2+ or Hg+ but not with Zn2+, Cd2+, Co2+, Ni3+, Fe3+, or Cr3+ interacted with WDp. Finally, we model the protein-protein interaction and present a theoretical representation of the HAH1p·Cu·WD/MNKp complex.
Sulfonylurea Receptor Transmembrane Domain Zero Mutations that Disrupt Full Length and Minimal ATP-Sensitive Potassium Channel Properties

Kir6.2 subunits constitute the pore-domain of the ATP-sensitive potassium channel (KATP) and, as such, are acted upon by accessory sulfonylurea receptor (SUR1) subunits to transduce ligand and pharmacologic signals into channel activity modifications. It is the interface of these two subunits that this work attempts to illuminate. We recently characterized two disease-causing mutations positioned in the first transmembrane domain of SUR1 (R74W and E128K located in TMD0) that decrease both ATP-sensitive inhibition and intrinsic open-probability (Po) of KATP. Because TMD0 has been shown to endow KATP channels with increased Po, we hypothesized that R74 and E128 lie at the subunit-subunit interface between SUR1 and Kir6.2 and their mutation leads to decreased SUR1-Kir6.2 interactions. We first characterized the amino-acid side-chain properties of R74x and E128x that determine channel surface expression and ATP-sensitive inhibition via a mutagenesis-based screen. Aromatic residues at R74 resulted in dramatic reduction of ATP-induced inhibition (IC50) whereas any non-charge conserving residue caused significant loss of surface expression. E128x mutations that decreased the ATP IC50 caused a parallel reduction of surface expression; residue charge, hydrophobicity, or size were independent of this relationship. To more directly assess TMD0SUR1-Kir6.2 stability, we compared single channel voltage-clamp recordings of channels formed by Kir6.2 alone (Kir6.2delta35C ) to minimal KATP channels (i.e., TMD0 + Kir6.2delta35C) with and without R74W or E128K mutations. Intrinsic open probabilities of mutant minimal channels were significantly less than WT TMD0+Kir6.2delta35C, yet not less than Kir6.2deltaC alone. Our results support the hypothesis that contacts between TMD0 and Kir6.2_rather than the influence of SUR1 regions terminal to TMD0_are disrupted by introduction of mutations at R74 and E128.
Negotiating boundaries in the definition of life: Wittgensteinian and Darwinian insights on resolving conceptual border conflicts

What is the definition of life? Artificial life environments provide an interesting test case for this classical question. Understanding what such systems can tell us about biological life requires negotiating the tricky conceptual boundary between virtual and real life forms. Drawing from Wittgenstein’s analysis of the concept of a game and a Darwinian insight about classification, I argue that classifying life involves both causal and pragmatic elements. Rather than searching for a single, sharp definition, these considerations suggest that life is a cluster concept with fuzzy boundaries and that there are multiple legitimate ways to make the notion precise for different scientific purposes. This pluralist, realist account avoids unnecessary border disputes by emphasizing how science negotiates such questions in relation to theory and evidence. I also discuss several objections to this approach, including a “moral hesitation” some have to allowing broader application of the concept of life to include artificial life.
Risk factors for cesarean delivery in twin pregnancies attempting vaginal delivery.

Objective The purpose of this study was to estimate independent risk factors for cesarean delivery in patients with twin pregnancies who attempt vaginal delivery. Study Design This was an historic cohort of twin pregnancies that were delivered in 1 practice from June 2005 to February 2014. Baseline characteristics were compared between women who delivered vaginally and women who underwent cesarean delivery in labor. Logistic regression analysis was performed to estimate independent risk factors for cesarean delivery. Results Two hundred eighty-six women with twin pregnancies who had attempted vaginal delivery were included in the study. The overall modes of delivery were vaginal delivery (82.2%), cesarean delivery (17.8%), and combined vaginal-cesarean delivery (0%). The most common indication for cesarean delivery in labor was an arrest disorder (82.4%). The risk factors that were associated independently with cesarean delivery were nulliparity (adjusted odds ratio, 5.78; 95% confidence interval, 2.24–14.88) and advanced maternal age of ≥35 years (adjusted odds ratio, 2.36; 95% confidence interval, 1.16–4.80). The patients at highest risk for cesarean delivery (nulliparous, advanced maternal age, induced labor) still had a 48.6% likelihood of vaginal delivery. Conclusion In patients with twin pregnancies who attempt labor, nulliparity and advanced maternal age are associated independently with cesarean delivery in labor. However, even the patients at highest risk for cesarean delivery have nearly a 50% likelihood of successful vaginal delivery and therefore should be allowed to attempt vaginal delivery if it is desired and not otherwise contraindicated.
Cocaine does not affect prostacyclin, thromboxane or prostaglandin E production in human umbilical veins

Vasoactive prostaglandins have been reported to mediate umbilical/placental blood flow in humans. Since it has been suggested that cocaine exerts its teratogenic action via vasoconstriction and a corresponding reduction in blood flow, it is reasonable to hypothesize that cocaine influences the vasoactive prostaglandins such that blood flow would be affected. The purpose of this study, therefore, was to determine the effects of cocaine on the vasoactive prostaglandins prostacyclin, thromboxane, and prostaglandin E, using human umbilical veins. Prostacyclin (PGI2), thromboxane (TXA2), and prostaglandin E (PGE) levels were measured from human umbilical veins collected at term. The veins were perfused in a closed system with either a 50 μg/ml, a 100 μg/ml, a 200 μg/ml, or a 400 μg/ml cocaine solution for 60 min, and the prostaglandins were measured by radioimmunoassay of their stable metabolites. Data were analyzed by ANOVA, and post-hoc analyses were performed by Fisher's Protected Least Significant Difference Test. Cocaine did not influence PGI2, TXA2, or PGE production (Ps > 0.05) in this series of studies. Thus, contraction of human umbilical vessels and decreased blood flow in human umbilical vessels does not appear to be mediated by changes in the vasoactive prostaglandins.
Mutual interactions between electrochemistry, organic chemistry and biological sciences

Abstract Mutual interactions involving electroanalytical methods, organic chemistry, biochemistry, and biology are discussed. Knowledge acquired in organic chemistry assisted understanding of structural effects and mechanisms of organic electrode processes. Possibility to apply LFER to a great variety of electrochemical data indicates parallelism between reactivity in organic electrode processes and homogeneous reactions. Electron-density distribution rather than adsorbability of an organic compound is hence the predominant factor in organic electrochemistry, at least at mercury electrodes. Contributions of electrochemistry to organic chemistry involve quantitative data on reactivity changes and information on mechanisms for both slow and fast reactions. Such contributions are demonstrated on nucleophilic additions to α,β-unsaturated systems, Cannizzaro reaction, as well as on hydration-dehydration equilibria involving aldehydes, 1,2-diketones, and α-ketoacids. Contributions to biochemistry are represented by elucidation of mechanisms of some biochemically important reactions, such as the formation of Schiff bases, detection and identification of some metabolites of physiologically active compounds and studies of bioanalytical reactions, such as determination of arginine groups. Correlations of physiological activity with electrochemical data can show if chemical reactivity is the predominating factor in physiological activity.
Fiber-tip resonator excited by radiation pressure and photo-thermal effect

A mechanical resonator was fabricated on the tip of a standard single mode fiber with outer diameter of 125 μm. The fabrication process involved a single-mode to a multimode fiber splicing, sputtering coating of a submicron gold nanofilm, focused ion beam (FIB) patterning and chemical wet etching. A micro-vibrating disk with suspension arms was formed on the sensing fiber tip, the resonance frequency of the vibrator is sensitive to mass loading on its surface. Vibration was excited by laser excitation via the radiation pressure and the photo-thermal effect and detected by a CW laser beam at another wavelength. The detected intensity of the fundamental and higher order harmonics can be monitored for resonance frequency determination. The excitation and detection beams were multiplexed within a single fiber link, which makes the sensor compact and versatile. The resonator maintained relatively high quality factor in air and was successfully applied to the analysis of layer-by-layer electrostatic self-assembly and immuno-sensing.
The typical leadership study: Assumptions, implications, and potential remedies.

Since the turn of the century, the area of leadership has seen notable growth in the amount of research conducted. As such, it now seems appropriate to evaluate how most leadership research is conducted, considering in particular the assumptions that are made when conducting the typical leadership study. Specifically, we explored the assumptions made with regard to (a) subordinates, (b) leaders, (c) context, and (d) the processes involved in leadership. Consideration of these assumptions reveals a number of problems ranging from simple methodological issues to more substantive theory-based concerns. Potential remedies are presented, along with a consideration of the long-term impact associated with the typical leadership study approach.
Bounds on the dimensions of trivariate spline spaces

We derive upper and lower bounds on the dimensions of trivariate spline spaces defined on tetrahedral partitions. The results hold for general partitions, and for all degrees of smoothness r and polynomial degrees d.
Kinetic monitoring of enzymatic reactions in real time by quantitative high-performance liquid chromatography-mass spectrometry.

Abstract The study of enzyme kinetics under steady-state conditions represents a common and very useful method for investigating the mechanisms of enzymatic reactions. We report the use of mass spectrometry (MS) coupled with HPLC for the kinetic analysis of enzymatic reactions in real time. The hydrolysis of dinucleotides with bovine pancreatic ribonuclease A (RNase A) and the substrate-specific hydrolysis of lactose with β-galactosidase can be monitored using ion-spray (pneumatically assisted electrospray) mass spectrometry as a sensitive and specific detector for the native substrates. The resulting data can be used to calculate both K M and V max for each system. Kinetic parameters obtained for RNase A and β-galactosidase paralleled those obtained by conventional techniques. These findings suggest the possibility of developing alternative techniques, based on mass spectrometric detection, for performing kinetic analyses of enzymatic processes where no simple spectrophotometric assay is feasible. In addition to enabling the determination of kinetic parameters for authentic substrates, and not chromogenic analogs, such assays would also be useful in situations where very high sensitivity and specificity are desired.
GENERIC CHARACTERIZATION OF ACTINOCYCLUS: CONSIDERATION IN LIGHT OF THREE NEW SPECIES

Three new species of Actinocyclus are described: A. circellus, from the Gulf of Mexico and North Atlantic (in Gulf Stream warm core rings); A. vestigulus, also from warm core rings; and A. spiritus, from antarctic waters. The morphology of these species provides insights into the generic characterization and evolution of Actinocyclus. The taxononomic preeminence of the pseudonodulus is challenged; a morphological continuum supports the suggestion that the pseudonodulus formed from a fusion of several marginal areolae. A possible rudimentary labiate process is shown near the centre of a forming valve of A. vestigulus, suggesting that Actinocyclus at least shares a common ancestor with Azpeitia. Segmented bands were seen on the largest of the three species, A. circellus.
Work-Family Fit: The Impact of Emergency Medical Services Work on the Family System

Introduction. The stress associated with a career in emergency medical services (EMS) can impact the work–family fit and function of the family system for EMS personnel. Little research has been conducted on how the demands associated with a career in EMS influences family life. Objective. To describe salient EMS work factors that can impact the family system. Methods. Twelve family members (11 spouses and one parent) of EMS workers were interviewed using a semistructured qualitative interview guide that explored issues related to their family members' work that could impact the quality of family life. Using a phenomenological approach, transcribed interview data were examined for themes that illuminated factors that influence work–family fit. Results. Data analysis revealed that shift work impacts numerous aspects of family life, including marital and parental roles, leisure and social opportunities, and home schedules and rhythms. Furthermore, families coped with challenges associated with their loved o...
Pharmacomechanical thrombolysis and early stent placement for iliofemoral deep vein thrombosis.

PURPOSE To evaluate an approach to the treatment of iliofemoral deep vein thrombosis (DVT) that included pharmacomechanical catheter-directed thrombolysis with reteplase and the Helix mechanical thrombectomy device, followed by early stent placement. MATERIALS AND METHODS During 3-year period, 23 symptomatic limbs in 18 patients with iliofemoral DVT were treated with reteplase catheter-directed thrombolysis. After an initial infusion of 8 to 16 hours, any residual acute thrombus over a long segment (> 10 cm) was treated by maceration with use of the Helix thrombectomy device. Residual short-segment ( RESULTS Technical success was achieved in 23 of 23 limbs (100%). Clinical success was achieved in 22 of 23 limbs (96%). Complete or partial thrombolysis was observed in 19 of 23 limbs (83%). Major bleeding was observed in one patient (6%) and necessitated blood transfusion. Mean per-limb thrombolytic infusion time and total dose were 19.6 hours ± 8.1 and 13.8 U ± 5.3 reteplase, respectively. Mean serum fibrinogen nadir and percentage drop in serum fibrinogen were 282 mg/dL ± 167 and 47% ± 24%, respectively. Late (mean, 19.8 ± 11.6 months) modified Venous Disability Scores were 0 (none) for six limbs, 1 (mild) for 10 limbs, 2 (moderate) for two limbs, and 3 (severe) for no limbs. CONCLUSIONS In a preliminary experience, pharmacomechanical catheter-directed iliofemoral DVT thrombolysis with early stent placement was safe and effective.
Heat transfer during Nd: Yag pulsed laser welding and its effect on solidification structure of austenitic stainless steels

Theoretical and experimental investigations were carried out to determine the effect of process parameters on weld metal microstructures of austenitic stainless steels during pulsed laser welding. Laser welds made on four austenitic stainless steels at different power levels and scanning speeds were considered. A transient heat transfer model that takes into account fluid flow in the weld pool was employed to simulate thermal cycles and cooling rates experienced by the material under various welding conditions. The weld metal thermal cycles and cooling rates are related to features of the solidification structure. For the conditions investigated, the observed fusion zone structure ranged from duplex austenite (γ)+ferrite (δ) to fully austenitic or fully ferritic. Unlike welding with a continuous wave laser, pulsed laser welding results in thermal cycling from multiple melting and solidification cycles in the fusion zone, causing significant post-solidification solid-state transformation to occur. There was microstructural evidence of significant recrystallization in the fusion zone structure that can be explained on the basis of the thermal cycles. The present investigation clearly demonstrated the potential of the computational model to provide detailed information regarding the heat transfer conditions experienced during welding.
The application of voltage regulators to aircraft generators

The use of high-capacity d-c generators on aircraft has required the development of regulators with rapid response, high accuracy, and with features for parallel operation of variable speed machines. The fundamental requirements of light weight, ability to withstand shock and vibration, and to give low radio interference were vital factors considered in the development. A device incorporating these features. is described and analyzed. Results of tests on these equipments have shown that regulators with these features are vital to the operation of the electrical loads of modern planes, both the military and commerical types. The tests show that the requirements have been met with devices suited to high production methods.
On the upper bound of α-lifetime for large sensor networks

In this article, we explore the fundamental limits of sensor network lifetime that all algorithms can possibly achieve. Specifically, under the assumptions that nodes are deployed as a Poisson point process with density λ in a square region with side length e and each sensor can cover a unit-area disk, we first derive the necessary and sufficient condition of the node density in order to maintain complete k-coverage with probability approaching 1. With this result, we obtain that if λ = log e2 p (k p 2)loglog e2 p c(e), c(e) → −∞, as e → p ∞, the sensor network lifetime (for maintaining complete coverage) is upper bounded by kT with probability approaching 1 as e → p ∞, where T is the lifetime of a single sensor. Second, we derive, given a fixed node density in a finite (but reasonably large) region, the upper bounds of lifetime when only α-portion of the region is covered at any time. We also carry out several sets of experiments to validate the derived theoretical results. Numerical results indicate that the derived upper bounds apply not only to networks of large sizes and homogeneous nodal distributions but also to small size networks with clustering nodal distributions.
Thermally stable polymers from condensation polymerization of perfluoroalkylamidines

Perfluoroalkyldiamidines and cyclic perfluoroalkylimidines undergo condensation polymerization with the liberation of ammonia to produce infusible polymers that are stable to heating in air at 350° and are not attacked by strong oxidizing agents. Copolymerization of perfluoroalkyldiamidines or perfluoroalkylimidines with perfluoroalkylmonoamidines produces polymers that are equally stable at high temperatures and that range in physical characteristics from viscous liquids to elastomeric gums. A probable structural unit for this new polymer system consists of s-triazine rings linked by perfluoroalkyl chains.
Structural analysis of diheme cytochrome c by hydrogen-deuterium exchange mass spectrometry and homology modeling.

A lack of X-ray or nuclear magnetic resonance structures of proteins inhibits their further study and characterization, motivating the development of new ways of analyzing structural information without crystal structures. The combination of hydrogen–deuterium exchange mass spectrometry (HDX-MS) data in conjunction with homology modeling can provide improved structure and mechanistic predictions. Here a unique diheme cytochrome c (DHCC) protein from Heliobacterium modesticaldum is studied with both HDX and homology modeling to bring some definition of the structure of the protein and its role. Specifically, HDX data were used to guide the homology modeling to yield a more functionally relevant structural model of DHCC.
Dopant site location in dual-implanted GaP using (111) planar channeling

Previous studies have indicated that dual implantation can efficiently introduce group IV dopant onto selected sub-lattice sites in m-V compound semiconductors, thus enhancing electrical activation. We studied this phenomenon in GaP using Rutherford Backscattering Spectroscopy (RBS) to determine the lattice location of Sn atoms. We used single crystals of GaP (100) which had been implanted at 400° C with 120 Sn + following previously implanted 69 Ga + or 31 P + . Energies were selected for euivalent projected ranges, and all species were implanted with doses of 1 × 10 15 atoms/cm 2 . Asymmetry in the angular scan of the {111} planar channel was then used to determine the sub-lattice location of the implanted Sn. RBS results indicated that for all implants Sn atoms were substituting Ga and P sites eually. However, Hall effect measurements gave p type conduction for GaP implanted with Sn alone, while those with prior implants of Ga or P resulted in n-type conduction. RBS and Hall effect results are explained by a vacancy complex model.
Career Development among First-Year College Students: College Self-Efficacy, Student Persistence, and Academic Success.

The present study investigates the career development of college student persistence decisions through the theoretical lens of social cognitive career theory (SCCT). Specifically, the authors sough...