cssi/SciSciGPT-SciSciNet huggingface dataset:
Rhodium catalyzed intramolecular [4+2] cycloisomerization reactions

A rhodium catalyst is reported that catalyzes the cycloisomerization of dieneynes and trienes. This cycloisomerization reaction, formally the equivalent of an unactivated Diels-Alder reaction, proceeds at room temperature with [Rh(DIPHOS)(CH2Cl2)2] SbF6 as the catalyst.
The number of rooted maps on an orientable surface

Abstract Let mg(n) be the number of rooted n edged maps on an orientable surface of genus g > 0. The generating function Mg(x) = Σ mg(n) xn is a rational function of ϱ = (1 − 12x) 1 2 whose denominator factors completely into powers of ϱ, ϱ + 2, and ϱ + 5. We calculate M2(x) and M3(x). Unfortunately, we have not been able to discern a pattern in the sequence Mg(x) from the values for g ≤ 3.
An enantiomerically pure bilirubin. Absolute configuration of (αR,α′R)-dimethylmesobilirubin-XIIIα

Abstract Enantiomerically pure (+)-(α R ,α′ R )-dimethylmesobilirubin-XIIIα 1 and its (α S ,α′ S ) enantiomer ent - 1 were synthesized in ten steps from simple precursors. Resolution was achieved at an early stage in the synthesis, with a racemic monopyrrole precursor rac - 6 being converted to its amides 8 with (1 S )-camphor-2,10-sultam. Resolution of 8 to 99% d.e. was accomplished in three crystallizations, and the absolute configuration of the acid 6 was deduced by X-ray crystallography of the more crystalline, diastereomerically pure amide 7 . Circular dichroism spectroscopy of 1 showed intense bisignate Cotton effects: Δ e max 435 =+344, Δ e max 391 =−193 (CHCl 3 ), as expected for a molecular exciton, and consistent with a P -helical intramolecularly hydrogen-bonded ridge-tile conformation. The Cotton effect magnitudes of 1 match almost exactly those found for (−)-(β S ,β′ S )-dimethylmesobilirubin-XIIIα 11 and (+)-(α R ,β′ R )-dimethylmesobilirubin-XIIIα. However, the Cotton effect of the pseudo- meso diastereomer (α R ,β′ S )-dimethylmesobilirubin-XIIIα 12 is not zero. Its large positive exciton couplet and 1 H NMR NOE analysis confirm that an α-CH 3 exerts a greater steric demand than a β-CH 3 —by a factor of ∼3.
Decomposition of Prediction Error in Multilevel Models

ABSTRACT We present a decomposition of prediction error for the multilevel model in the context of predicting a future observable y *j in the jth group of a hierarchical dataset. The multilevel prediction rule is used for prediction and the components of prediction error are estimated via a simulation study that spans the various combinations of level-1 (individual) and level-2 (group) sample sizes and different intraclass correlation values. Additionally, analytical results present the increase in predicted mean square error (PMSE) with respect to prediction error bias. The components of prediction error provide information with respect to the cost of parameter estimation versus data imputation for predicting future values in a hierarchical data set. Specifically, the cost of parameter estimation is very small compared to data imputation.
The Design of QoS Broker Algorithms for QoS-Capable Web Services

QoS (quality of service) support in Web services is an important issue since it ensures service usability and utility for each client and, in addition, improves server utilization. In this article, we present a QoS-capable Web service architecture, QCWS, by introducing a QoS broker module between service clients and providers (servers). The functions of the QoS broker module include tracking QoS information about servers, making selection decisions for clients, and negotiating with servers to get QoS agreements. We study two resource allocation algorithms (HQ and RQ) used by QoS brokers acting as the front-end of servers. The goals of the algorithms are to maximize the server resource usage while minimizing the QoS instability for each client. The first algorithm, HQ, assigns a homogeneous service level to all clients on the system and adjusts the service level according to the number of active clients. The second algorithm, RQ, assigns different service levels to clients according to their needs. Both algorithms try to minimize the resource reallocations for existing clients. The QoS performance and instability trade-offs are studied by simulation.
Improving the Retinex algorithm for rendering wide dynamic range photographs

Digital photography systems often render an image from a scene-referred description with very wide dynamic range to an output-referred description of much lesser dynamic range. Global tone maps are often used for this purpose, but can fail when called upon to perform a large amount of range compression. A luminance formulation of the Retinex ratio-reset-product-average algorithm produces a smoothly changing contrast mask of great benefit, but it too can fail where high contrast edges are encountered. A slight but critical modification to the Retinex equation - introducing a ratio modification operator - changes the nature of the generated contrast mask so that it is simultaneously smooth in regions of small contrast ratios, but extremely sharp at high contrast edges. A mask produced in this way compresses large and undesirable contrast ratios while preserving, or optionally enhancing, small ratios critical to the sensation of image contrast. Processed images may appear to have a greater contrast despite having a shorter global contrast range. Adjusting the new operator prior to processing gives control of the degree of compression at high contrast edges. Changing the operator during processing gives control over spatial frequency response.
Pathways for virus assembly around nucleic acids.

Abstract Understanding the pathways by which viral capsid proteins assemble around their genomes could identify key intermediates as potential drug targets. In this work, we use computer simulations to characterize assembly over a wide range of capsid protein–protein interaction strengths and solution ionic strengths. We find that assembly pathways can be categorized into two classes, in which intermediates are either predominantly ordered or disordered. Our results suggest that estimating the protein–protein and the protein–genome binding affinities may be sufficient to predict which pathway occurs. Furthermore, the calculated phase diagrams suggest that knowledge of the dominant assembly pathway and its relationship to control parameters could identify optimal strategies to thwart or redirect assembly to block infection. Finally, analysis of simulation trajectories suggests that the two classes of assembly pathways can be distinguished in single-molecule fluorescence correlation spectroscopy or bulk time-resolved small-angle X-ray scattering experiments.
Infections in children with severe protein-energy malnutrition.

SUMMARYThe infections occuring in 68 black children admitted to hospital with kwashiorkor, marasmus or marasmic-kwashiorkor were studied prospectively. Fifteen episodes of bacteraemia, most commonly due to Gram-negative enteric bacilli, occurred in 13 children (19%), six of these episodes being nosocomial. Urinary tract infection, diagnosed on suprapubic urine specimens and all due to Escherichia coli, occurred in five out of 16 cases (31%). In the 48 cases admitted with gastro-enteritis and 18 with pneumonia, a causative organism was found in the minority. Fifteen episodes of nosocomial infection occurred in 14 children (20·6%), of whom four died. Of the 14 deaths, eight were associated with bacteraemia. Skin infections were due mainly to staphylococci and streptococci. Infections in severely malnourished children appear to be due largely to the same microorganisms as cause infection in well-nourished children of the same community. Nosocomial infections pose a major threat to these children.
Demagnetization Control for Reliable Flux Weakening Control in PM Synchronous Machine

A process for permanent magnet (PM) demagnetization control for optimal and reliable flux weakening control in permanent magnet synchronous machines (PMSM) is presented. A physics-based model was developed to estimate the magnetic flux operating point of the PM poles during the operation of PMSM. The model is enabled to dynamically estimate the average and the partial PM demagnetization due to reverse armature field as well as the PM temperature rise. The model is a function of physical geometry and material of the PMSM, physics of demagnetization, and the ambient temperature. The demagnetization assessment and control is verified on a V-type PMSM using the modified FE-based coupled thermal-field-circuit phase variable model and the time step FE analysis.
On the reliable measurement of the gluon condensate in lattice QCD

We propose to calculate the gluon condensate in lattice QCD in an indirect way by extracting it from the correlator of hadronic currents of heavy quarks. Moments (derivatives with respect to moments m at vanishing momentum) of the vector and pseudoscalar correlators are evaluated. The contribution of the continuum spectrum in addition to the low-lying resonance is observed in accordance with qualitative expectations. Finite size effects are observed and shown to be insignificant for heavy quarks and moderate lattices. A practical definition of the nonperturbatively renormalized heavy quark mass is given.
Cavitation-erosion resistance of 316LN stainless steel in mercury containing metallic solutes

Room temperature cavitation tests of vacuum annealed type 316LN stainless steel were performed in pure mercury and in mercury with various amounts of metallic solute to evaluate potential mitigation of erosion/wastage. Tests were performed using an ultrasonic vibratory horn with specimens attached at the tip. All of the solutes examined, which included 5 wt% In, 10 wt% In, 4.4 wt% Cd, 2 wt% Ga, and a mixture that included 1 wt% each of Pb, Sn, and Zn, were found to increase cavitation-erosion as measured by increased weight loss and/or surface profile development compared to exposures for the same conditions in pure mercury. Qualitatively, each solute appeared to increase the tenacity of the post-test wetting of the Hg solutions and render the Hg mixture susceptible to manipulation of droplet shape.
Numerical and theoretical analyses of in-plane dynamic rupture on a frictional interface and off-fault yielding patterns at different scales

S U M M A R Y We perform numerical simulations of in-plane ruptures with spontaneous Mohr-Coulomb yielding in the bulk and analyse properties of the ruptures and yielding zones at different scales. Using a polar coordinate system, we show that the overall shapes and patterns of the simulated yielding zones can be well explained by combining the slip-induced Coulomb stress change and the background stress. Although there is no apparent mechanism for preferring synthetic versus antithetic shearing at a scalemuch smaller than the yielding zone size, this is not the case at larger scales. For shallow angles Ψ between the maximum background compressive stress and the fault, representing thrust faulting, large-scale off-fault synthetic fractures are dominant but there are two conjugate sets of fractures with a typical size comparable to the yielding zone thickness. For smooth rupture propagation with moderate-to-high Ψ values representing large strike-slip faults, most of the off-fault fractures that grow across the entire yielding zone are of the synthetic type. The less preferred antithetic set may become more pronounced for rupture propagation encountering fault heterogeneities. In particular, a strong fault barrier promotes antithetic fractures with a comparable size to those of the synthetic type around the barrier, where very high permanent strain is also observed. A consideration of non-local properties of the stress field in space or time can explain the above differences. Our results provide an alternative way of understanding Riedel shear structures and the potentially preferred synthetic shear fractures suggested in previous studies. The examined dynamic processes may be distinguished from quasi-static patterns by the timing, location and inclination angle of characteristic fracture elements. In agreement with other studies, we propose that backward or orthogonally inclined antithetic shear fractures on strike-slip faults and very high permanent strain could be used as signals that reflect abrupt rupture deceleration. On the other hand, relative lack of off-fault yielding at given locations may indicate abrupt rupture acceleration.
The NBA, Exit Discrimination, and Career Earnings

The purpose of this paper is threefold. First, it complements the many wage discrimination studies by examining exit discrimination in the NBA using a decade's worth of data (the 1980's). White players have a 36% lower risk of being cut than black players, ceteris paribus, translating into an expected career length of 7.5 seasons for an apparently similar player who is white, and 5.5 seasons for the same player who is black. Second, the career earnings effect of exit discrimination in the 1980's is larger ($808,000) than the career earnings effect of wage discrimination ($329,000). Third, our data are consistent with the hypothesis that customer racial discrimination is the reason for the observed exit discrimination.
Housing in Environmental Complexity Following Wheel Running Augments Survival of Newly-Generated Hippocampal Neurons in a Rat Model of Binge Alcohol Exposure during the Third Trimester Equivalent

Background Binge-like alcohol exposure in neonatal rats during the brain growth spurt causes deficits in adult neurogenesis in the hippocampal dentate gyrus (DG). Previous data from our laboratory demonstrated that 12 days of voluntary wheel running (WR) beginning on postnatal day (PD) 30 significantly increased the number of newly generated cells evident in the DG on PD42 in both alcohol-exposed (AE) and control rats, but 30 days later a sustained beneficial effect of WR was evident only in control rats. This study tested the hypothesis that housing rats in environmental complexity (EC) following WR would promote the survival of the newly generated cells stimulated by WR, particularly in AE rats. Methods On PD4 to 9, pups were intubated with alcohol in a binge-like manner (5.25 g/kg/d), sham-intubated (SI), or reared normally. In Experiment 1, animals were either assigned to WR during PD30 to 42 or socially housed (SH). On PD42, animals were injected with bromodeoxyuridine (BrdU; 200 mg/kg) and perfused 2 hours later to confirm the WR-induced stimulation of proliferation. In Experiment 2, all animals received WR on PD30 to 42 and were injected with BrdU on the last full day of WR. On PD42, animals were randomly assigned either to EC (WR/EC) or to SH (WR/SH) for 30 days and subsequently perfused and brains were processed for immunohistochemical staining to identify BrdU+-, Ki67+-, and BrdU+/NeuN+-labeled cells in DG. Results In Experiment 1, WR exposure significantly increased the number of proliferating cells in all 3 postnatal conditions. In Experiment 2, the AE rats given WR/SH had significantly fewer BrdU+ cells compared with control rats given WR/SH. However, WR/EC experience significantly increased the number of surviving BrdU+ cells in both the AE and SI groups compared with WR/SH rats of the same neonatal treatment. Approximately 80% of the surviving BrdU+ cells in the DG across the conditions were colabeled with NeuN. Conclusions WR followed by EC could provide a behavioral model for developing interventions in humans to ameliorate hippocampal-dependent impairments associated with fetal alcohol spectrum disorders.
Ultrafast electron dynamics at metal interfaces: intraband relaxation of image state electrons as friction.

Two-photon photoemission of image potential states above monolayers of p-xylene/Ag(111) shows that electrons with different momenta have very different rise and decay rates as a function of parallel momentum. The dynamics are due to energy and momentum loss (intraband relaxation), which we model as a stochastic process isomorphic to the overdamped motion of a harmonic oscillator. The method extracts a friction coefficient from the data which can be explained by electron−electron scattering in a formalism based on the Lindhard dielectric function. One-electron excitations (interband transistions) dominate the dissipation mechanism, with a smaller contribution from collective electronic excitations (plasmons).
Weakly Bound Molecules in the Atmosphere: A Case Study of HOOO

Weakly bound molecules—particularly hydrated complexes of abundant atmospheric species—have long been postulated to play an important role in atmospherically relevant reactions. For example, such complexes could seed cloud formation and alter the global radiation budget. In this Account, we initially describe the current data on weakly bound species produced in association reactions of the hydroxyl radical (OH) with molecular partners, particularly oxygen (O2), nitric acid (HONO2), and nitrogen dioxide (NO2). Researchers have identified weakly bound association products of these reactions as the hydrogen trioxy (HOOO) radical, the doubly hydrogen-bonded OH−HONO2 complex, and peroxynitrous acid (HOONO), respectively. In each case, previous kinetic studies of the reaction or OH vibrational relaxation processes have indicated unusual, non-Arrhenius behavior. Under the temperature−pressure conditions of the Earth’s lower atmosphere, these processes exhibit a negative temperature dependence, indicative of an a...
Annihilating the cohomology of group schemes

Our goal in this note is to show that cohomology classes with coefficients in finite flat group schemes can be killed by finite covers of the base scheme, and similarly for abelian schemes with “finite covers” replaced by “proper covers.” We apply this result to commutative algebra by giving a new and more conceptual proof of Hochster-Huneke’s theorem on the existence of big Cohen-Macaulay algebras in positive characteristic; all previous proofs of this result were equational or cocycle-theoretic in nature.
Quantum corrections to Q -balls

Abstract We extend calculational techniques for static solitons to the case of field configurations with simple time dependence in order to consider quantum effects on the stability of Q -balls. These non-topological solitons exist classically for any fixed value of an unbroken global charge Q . We show that one-loop quantum effects can destabilize very small Q -balls. We show how the properties of the soliton are reflected in the associated scattering problem, and find that a good approximation to the full one-loop quantum energy of a Q -ball is given by ω − E 0 , where ω is the frequency of the classical soliton's time dependence, and E 0 is the energy of the lowest bound state in the associated scattering problem.
Conditional Probabilities and Density Operators in Quantum Modeling

Motivated by a recent proof of free choices in linking equations to the experiments they describe, I clarify some relations among purely mathematical entities featured in quantum mechanics (probabilities, density operators, partial traces, and operator-valued measures), thereby allowing applications of these entities to the modeling of a wider variety of physical situations. I relate conditional probabilities associated with projection-valued measures to conditional density operators identical, in some cases but not in others, to the usual reduced density operators. While a fatal obstacle precludes associating conditional density operators with general non-projective measures, tensor products of general positive operator-valued measures (POVMs) are associated with conditional density operators. This association together with the free choice of probe particles allows a postulate of state reductions to be replaced by a theorem. An application shows an equivalence between one form of quantum key distribution and another with respect to certain eavesdropping attacks.
The electrochemistry of amavadine, a vanadium natural product

Abstract Amavadine, a vanadium natural product of the mushroom Amanita muscaria , has been synthesized and its electrochemistry characterized in DMSO, DMF, and water. In each solvent a one electron reversible oxidation couple is observed and the vanadium(V) product is stable. In DMSO the couple is at 0.03 V versus SCE and in water it occurs at 0.53 V. Several model complexes show irreversible oxidations at much higher potentials. The unique electrochemistry of Amavadine, as compared to the model complexes, suggests that it may function as an electron-transfer catalyst in the mushroom.
Flow stress model in metal cutting

A model for the plastic deformation that occurs in metal cutting, based on dislocation mechanics, is presented. The model explains the fundamental deformation structure that develops during machining and is based on the well known Cottrell-Stokes Law, wherein the flow stress is partitioned into two parts; an athermal part which occurs in the shear fronts (or shear bands); and a thermal part which occurs in the lamella regions. The deformation envokes the presence of a cellular dislocation distribution which always exists in the material ahead of the shear process. This 'alien' dislocation distribution either exists in the metal prior to cutting or is produced by the compressive stress field which operates in front of the shear process. The magnitude of the flow stress and direction of the shear are shown to be correlated to the stacking fault energy of the metal being cut. The model is tested with respect to energy consumption rates and found to be consistent with observed values.
The evolution of APL

This paper is a discussion of the evolution of the APL language, and it treats implementations and applications only to the extent that they appear to have exercised a major influence on that evolution. Other sources of historical information are cited in References 1-3; in particular, The Design of APL [1] provides supplementary detail on the reasons behind many of the design decisions made in the development of the language. Readers requiring background on the current definition of the language should consult APL Language [4].Although we have attempted to confirm our recollections by reference to written documents and to the memories of our colleagues, this remains a personal view which the reader should perhaps supplement by consulting the references provided. In particular, much information about individual contributions will be found in the Appendix to The Design of APL [1], and in the Acknowledgements in A Programming Language [10] and in APL\360 User's Manual [23]. Because Reference 23 may no longer be readily available, the acknowledgements from it are reprinted in Appendix A.
Inspection interval guidelines to reduce drillstring failures

This paper discusses inspection interval guidelines developed to reduce the occurrence of costly drillstring fatigue failures. The guidelines are based on a state-of-the-art fracture mechanics model and incorporate reliability data of commercial inspection services using conventional nondestructive testing techniques. On the basis of extensive full-scale testing, the model was found to predict fatigue-crack-growth behavior reliably. By establishing inspection intervals on the basis of fatigue-crack growth, inspection services are systematically and cost-effectively specified to achieve acceptable reliability (or risk). Simple equations and charts are presented in terms of practical drilling parameters to reduce typical downhole fatigue failures.
High-Temperature Thermoelectric Properties of the Solid-Solution Zintl Phase Eu11Cd6Sb12-xAsx (x < 3)

Zintl phases are compounds that have shown promise for thermoelectric applications. The title solid–solution Zintl compounds were prepared from the elements as single crystals using a tin flux for compositions x = 0, 1, 2, and 3. Eu_(11)Cd_6Sb_(12–x)As_x (x < 3) crystallize isostructurally in the centrosymmetric monoclinic space group C2/m (no. 12, Z = 2) as the Sr_(11)Cd_6Sb_(12) structure type (Pearson symbol mC58). Efforts to make the As compositions for x exceeding ~3 resulted in structures other than the Sr_(11)Cd_6Sb_(12) structure type. Single-crystal X-ray diffraction indicates that As does not randomly substitute for Sb in the structure but is site specific for each composition. The amount of As determined by structural refinement was verified by electron microprobe analysis. Electronic structures and energies calculated for various model structures of Eu_(11)Cd_6Sb_(10)As_2 (x = 2) indicated that the preferred As substitution pattern involves a mixture of three of the six pnicogen sites in the asymmetric unit. In addition, As substitution at the Pn4 site opens an energy gap at the Fermi level, whereas substitution at the other five pnicogen sites remains semimetallic with a pseudo gap. Thermoelectric properties of these compounds were measured on hot-pressed, fully densified pellets. Samples show exceptionally low lattice thermal conductivities from room temperature to 775 K: 0.78–0.49 W/mK for x = 0; 0.72–0.53 W/mK for x = 1; and 0.70–0.56 W/mK for x = 2. Eu_(11)Cd_6Sb_(12) shows a high p-type Seebeck coefficient (from +118 to 153 μ V/K) but also high electrical resistivity (6.8 to 12.8 mΩ·cm). The value of zT reaches 0.23 at 774 K. The properties of Eu_(11)Cd_6Sb_(12–x)As_x are interpreted in discussion with the As site substitution.
The Cepheid Luminosity Scale

The discrepancy between the luminosity scale for Cepheids derived from the intermediate band photometry and the presently accepted scale requires further investigation. We have discussed various factors which might affect the previous work and which might affect the present method but we are unable at this time to provide a definite explanation. However, since there is no obvious problem with the intermediate band photometry we should give serious consideration to the possibility that the Cepheid luminosity scale might require some revision.
An optimal two transmit antenna space-time code and its stacked extensions

A space-time code is proposed that exhibits the highest coding gain among competing full-rate full transmit diversity space-time codes for the two transmit and receive antenna coherent quasi-static fading channel. The proposed code is derived from a layered architecture with real rotation of quadrature amplitude modulation (QAM) information symbols in two dimensions. The existing codes of similar architecture concentrate on application of complex full modulation diversity rotations or asymmetric real rotations. An analytic evaluation illustrates the significant improvement in coding gain achieved with the proposed code. Moreover, the coding gain of the proposed code is independent of its rate. This implies that the proposed code achieves the optimal diversity-multiplexing tradeoff curve for the two transmit antenna system. A stacked extension of the proposed code offers a reduced complexity capacity optimal alternative to the full diversity codes for larger number of transmit antennas. Performance enhancement in several scenarios is verified through simulations.
Target zones and conditional volatility: The role of realignments

Abstract This paper examines the relationship between the conditional volatility of target zone exchange rates and realignments of the system. To investigate this question, modified jump-diffusion Generalized Autoregressive Conditional Heteroskedasticity (GARCH) and absolute value GARCH models are fit to six exchange rates of the Exchange Rate Mechanism (ERM) of the European Monetary System (EMS). Time-varying jump probability and absolute value GARCH models are effective in improving the fit of jump-diffusion models on target zone data. There is some evidence that conditional volatility is higher around the periods of realignments.
Extending the Notion of Quality from Physical Metrology to Information and Sustainability

In this paper we intend to demonstrate the need for extending the notion of quality from the physical domain to information and, more comprehensively, to sustainability. In physical metrology there are well established principles such as fundamental units, precision, accuracy, traceability and uncertainty. In order to understand and define quality for information and sustainability we need to develop metrological concepts similar to those of physical metrology. Research efforts related to information quality (IQ) are scattered. IQ is primarily defined in terms of several characteristics (dimensions) which lack consensus definitions and are sometimes subjective. However, the notion of IQ is currently in practice and has provided some useful insights towards defining formal approaches to IQ. In order to extend the notion of quality to sustainability we need, as in the case of information, a well defined metrology similar to physical metrology. Sustainability is currently getting attention in many areas of human endeavor. One proposal is to measure sustainability in terms of a triple bottom line, namely social, economical and environmental aspects of human endeavor. Sustainability metrics are continuously evolving and their clear definition is fundamental to the understanding of the notion of sustainability quality. As an example we consider evaluation of carbon footprint, as a metric towards sustainability, for manufacturing a simple turned part. After analyzing the current literature, we identify the following needs for characterizing the notion of sustainability quality: (a) standardized terminology of terms and concepts, (b) metrics and metrology, (c) harmonization and extension of standards, (d) conformance testbeds for standards and (e) development of information models that support sustainability.
A globally convergent, implementable multiplier method with automatic penalty limitation

This paper deals with penalty function and multiplier methods for the solution of constrained nonconvex nonlinear programming problems. Starting from an idea introduced several years ago by Polak, we develop a class of implementable methods which, under suitable assumptions, produce a sequence of points converging to a strong local minimum for the problem, regardless of the location of the initial guess. In addition, for sequential minimization type multiplier methods, we make use of a rate of convergence result due to Bertsekas and Polyak, to develop a test for limiting the growth of the penalty parameter and thereby prevent ill-conditioning in the resulting sequence of unconstrained optimization problems.
The investigation of dissolved and suspended-particulate trace metal fractionation in the Black Sea

Abstract A sequential filtration-ion-exchange column scheme has been developed for the investigation of dissolved trace metal fractionation. The method is designed to separate water column metals rapidly into particulate and colloidal-sized species, anionic dissolved metal-organic and/or metal-sulfide complexes, and ‘free’ (hydrated) metal cations and/or labile major ion complexes. The suspended-particulate matter (0.4 μm filterable material) is further subjected to a sequential leaching procedure to separate particulate metals into weak-acid leachable, strong-acid leachable, and refractory fractions. These methods are evaluated with respect to laboratory experiments and field results. These methods have been applied to the study of trace metal chemical fractionation in the Black Sea, the world's largest anoxic basin. We present here the results for Co, Ni, Cu, Zn, Cd, and Pb. The dissolved Co distribution is best explained in terms of a scavenging-regeneration cycle with Mn-oxyhydroxides across the sulfide interface and coprecipitation of Co with Fe-sulfides in the deep waters. Nickel displays nearly constant dissolved metal concentrations with depth and is apparently unaffected by redox processes. The Class B metals (Cu, Zn, Cd, and Pb) have high dissolved metal concentrations in the surface waters then decrease rapidly across the sulfide interface to low deep water concentrations, consistent with metal-sulfide precipitation below the interface. The dissolved Class B metal fractionation was generally dominated in the oxic zone by ‘free’ metal species, shifting below the interface to anionic species, probably dissolved metal-sulfide complexes. The suspended matter trace metal fractionation is dominated by weak-acid soluble forms throughout most of the water column. For particulate Co, strong-acid leachable forms, probably metal-sulfide phases, are important in the anoxic deep waters. The Class B metals form relatively reactive (weak-acid leachable) metal-sulfide precipitates just below the sulfide interface.
Power characteristics of inductive interconnect

The width of an interconnect line affects the total power consumed by a circuit. The effect of wire sizing on the power characteristics of an inductive interconnect line is presented in this paper. The matching condition between the driver and the load affects the power consumption since the short-circuit power dissipation may decrease and the dynamic power will increase with wider lines. A tradeoff, therefore, exists between short-circuit and dynamic power in inductive interconnects. The short-circuit power increases with wider linewidths only if the line is underdriven. The power characteristics of inductive interconnects therefore may have a great influence on wire sizing optimization techniques. An analytic solution of the transition time of a signal propagating along an inductive interconnect with an error of less than 15% is presented. The solution is useful in wire sizing synthesis techniques to decrease the overall power dissipation. The optimum linewidth that minimizes the total transient power dissipation is determined. An analytic solution for the optimum width with an error of less than 6% is presented. For a specific set of line parameters and resistivities, a reduction in power approaching 80% is achieved as compared to the minimum wire width. Considering the driver size in the design process, the optimum wire and driver size that minimizes the total transient power is also determined.
Phase response curve analysis of a full morphological globus pallidus neuron model reveals distinct perisomatic and dendritic modes of synaptic integration

Synchronization of globus pallidus (GP) neurons and cortically entrained oscillations between GP and other basal ganglia nuclei are key features of the pathophysiology of Parkinson's disease. Phase response curves (PRCs), which tabulate the effects of phasic inputs within a neuron's spike cycle on output spike timing, are efficient tools for predicting the emergence of synchronization in neuronal networks and entrainment to periodic input. In this study we apply physiologically realistic synaptic conductance inputs to a full morphological GP neuron model to determine the phase response properties of the soma and different regions of the dendritic tree. We find that perisomatic excitatory inputs delivered throughout the interspike interval advance the phase of the spontaneous spike cycle yielding a type I PRC. In contrast, we demonstrate that distal dendritic excitatory inputs can either delay or advance the next spike depending on whether they occur early or late in the spike cycle. We find this latter pattern of responses, summarized by a biphasic (type II) PRC, was a consequence of dendritic activation of the small conductance calcium-activated potassium current, SK. We also evaluate the spike-frequency dependence of somatic and dendritic PRC shapes, and we demonstrate the robustness of our results to variations of conductance densities, distributions, and kinetic parameters. We conclude that the distal dendrite of GP neurons embodies a distinct dynamical subsystem that could promote synchronization of pallidal networks to excitatory inputs. These results highlight the need to consider different effects of perisomatic and dendritic inputs in the control of network behavior.
Carnegie Hubble Program: A Mid-Infrared Calibration of the Hubble Constant

Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 μm with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble constant. We have established the mid-IR zero point of the Leavitt law (the Cepheid period-luminosity relation) using time-averaged 3.6 μm data for 10 high-metallicity, Milky Way Cepheids having independently measured trigonometric parallaxes. We have adopted the slope of the PL relation using time-averaged 3.6 μm data for 80 long-period Large Magellanic Cloud (LMC) Cepheids falling in the period range 0.8 < log(P) < 1.8. We find a new reddening-corrected distance to the LMC of 18.477 ± 0.033 (systematic) mag. We re-examine the systematic uncertainties in H 0, also taking into account new data over the past decade. In combination with the new Spitzer calibration, the systematic uncertainty in H 0 over that obtained by the Hubble Space Telescope Key Project has decreased by over a factor of three. Applying the Spitzer calibration to the Key Project sample, we find a value of H 0 = 74.3 with a systematic uncertainty of ±2.1 (systematic) km s–1 Mpc–1, corresponding to a 2.8% systematic uncertainty in the Hubble constant. This result, in combination with WMAP7 measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w 0 = –1.09 ± 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yield w 0 = –1.08 ± 0.10 and a value of N eff = 4.13 ± 0.67, mildly consistent with the existence of a fourth neutrino species.
Reduced order modeling of X-31 wind tunnel model aerodynamic loads

Abstract With recent advances in computational techniques, turbulent Navier–Stokes solvers are now capable of capturing the unsteady nonlinear aerodynamic behavior that leads to various static and dynamic instabilities of full aircraft. As such, the focus of stability and control (S&C) research has been to effectively incorporate Computational Fluid Dynamics (CFD) into the model development process using dynamic CFD solutions of complete aircraft configurations. This has lead to an innovative approach for modeling aircraft stability and control characteristics: (a) CFD simulations are performed using computational training maneuvers designed to excite the relevant flow physics encountered during actual missions, (b) a mathematical Reduced Order Model (ROM) is built of the aircraft response using system identification methods, (c) the model is validated by comparing CFD simulations against model predictions, and (d) predictions of all fight test points are made using the model to determine the expected behavior of the aircraft. This process would identify unexpected S&C issues early in the design process. This article describes the application of this innovative approach to a problem of the System Identification (SID) of a high performance fighter-type configuration, the X-31. The training maneuver used to produce the training data has been tested in the DNW low speed wind tunnel which enables directly comparing the predictive capabilities of the CFD and wind tunnel SID modeling.
Relative fluoride response of caries lesions created in fluorotic and sound teeth studied under remineralizing conditions.

Abstract Objectives The present in vitro pH cycling study investigated potential differences between caries lesions created in fluorosed and sound enamel with regards to their responsiveness to fluoride under remineralizing conditions. Methods 360 human first molars (sound and fluorosed) were divided into four groups based on their Thylstrup–Fejerskov score (TF0-3). Each group was further divided into two treatment groups (n = 45): deionized water or 383 ppm fluoride. Artificial enamel caries lesions were created and pH cycled for 20 d using an established net remineralization model. Quantitative light-induced fluorescence was used throughout the study to investigate lesion severity and changes thereof. Data were analyzed using two-way ANOVA. Results There were no differences in lesion severity between all groups after lesion creation (plesion = 0.1934). The TF score vs. treatment interaction was significant at all other time points (p10 d = 0.0280; p20 d ≤ 0.0001; psecdemin = 0.0411). Relative differences in responsiveness to fluoride vs. deionized water increased with increasing TF scores. In comparison to lesions created in sound enamel, lesions created in enamel with moderate fluorosis (TF 2/3) were more prone to remineralization in the presence than in the absence of fluoride. Furthermore, lesions created in enamel with moderate fluorosis exhibited more remineralization in the presence of fluoride than lesions created in sound teeth, whereas the opposite was true for deionized water. Conclusion Bearing in mind the limitations of laboratory research, the extent of enamel fluorosis severity may directly impact subsequent lesion re- and progression as well as the lesion's responsiveness to fluoride. Clinical relevance Caries lesions in fluorotic teeth are more vulnerable to progression but respond more strongly to fluoride than those in non-impacted teeth.
Preliminary Analysis of SOHO/STEREO Observations of Sungrazing Comet ISON (C/2012 S1) around Perihelion

We present photometric and morphological analysis of the behavior of sungrazing comet C/2012 S1 ISON in Solar and Heliospheric Observatory (SOHO) and Solar TErrestrial RElations Observatory (STEREO) images around its perihelion on 2013 November 28.779 UT. ISON brightened gradually November 20-26 with a superimposed outburst on November 21.3-23.5. The slope of brightening changed about November 26.7 and was significantly steeper in SOHO's orange and clear filter images until November 27.9 when it began to flatten out, reaching a peak about November 28.1 (r H ≈ 17 R ☉), then fading before brightening again from November 28.6 (r H ≈ 5 R ☉) until disappearing behind the occulting disk. ISON brightened continuously as it approached perihelion while visible in all other telescopes/filters. The central condensation disappeared about November 28.5 and the leading edge became progressively more elongated until perihelion. These photometric and morphological behaviors are reminiscent of the tens of meter-sized Kreutz comets regularly observed by SOHO and STEREO and strongly suggest that the nucleus of ISON was destroyed prior to perihelion. This is much too small to support published gas production rates and implies significant mass loss and/or disruption in the days and weeks leading up to perihelion. No central condensation was seen post-perihelion. The post-perihelion lightcurve was nearly identical in all telescopes/filters and fell slightly steeper than . This implies that the brightness was dominated by reflected solar continuum off of remnant dust in the coma/tail and that any remaining active nucleus was <10 m in radius.
TANDEM MANGANESE(III)-BASED OXIDATIVE FREE-RADICAL CYCLIZATIONS TERMINATED BY ADDITION TO FURANS. FORMAL SYNTHESIS OF 15-ACETOXYPALLESCENSIN-A

Reaction of β-keto ester 12 with 2 equiv. of Mn(OAc)32H2O in KOAc-buffered MeOH followed by acidic workup afforded 51% of tricyclic furan 14 indicating that oxidative cyclizations can be terminated by addition to furans. Reduction of 14 with LAH provided 7, completing a five-step formal synthesis of 15-acetoxypallescensin-A.
Experimental Results of Active Control on a Large Structure to Suppress Vibration

The need to suppress vibration in large space structures is a continuing problem during design. Active control of structural vibration is one method that can be used to achieve lightweight structures with desirable damping characteristics. In this paper three design methods, linear quadratic Gaussian with loop transfer recovery, //«>, and \L synthesis, are used to obtain compensators for suppressing the vibrations of a 10-bay vertical truss structure, a component typical of what may be used to build a large space structure. For the design process the plant dynamic characteristics of the structure were determined experimentally using an identification method. The resulting compensators were implemented on a digital computer and tested for their ability to suppress the first bending mode response of the 10-bay vertical truss. For these experiments, the first bending mode is excited and the control system is used to damp the vibration. Time histories of the measured motion are presented, and modal damping obtained during the experiments is compared with analytical predictions. The advantages and disadvantages of using the various design methods are discussed. Nomenclature A,B,C,D = coefficients of dynamic equation of motion G(z) = transfer function, discrete z transform = transfer function, continuous 5- transform = performance index = LQR feedback gain matrix = LQG/LTR gain matrix = HK compensator = LQR weighting matrices = output of a compensator or plant = sensitivity function = Laplace transform variable s, g(s) J Kq K& Q,R r,r(s) S
Paraffin isomerization and disproportionation catalyzed by Pd-loaded fluorided mordenites

Fluorided, Pd-loaded ({approximately}1.1 wt% Pd) mordenites, with 8, 12, 28, and 100% replacement of {minus}OH groups, were synthesized from H-mordenite. These materials were characterized by IR, XRD, SEM, the adsorption of N{sub 2} and 2-methylpentane, and their activity for paraffin reactions. Except in the case of 100% nominal fluoridation, the fluorided mordenites retained their crystallinity, displayed enhanced acid strengths and adsorption capacities for paraffinic hydrocarbons, and were catalytically active (at 533-573 K and {approximately}0.1 bar hydrocarbon partial pressure) for the transformation of n-butane to isobutane and products of both higher and lower molecular weights. The presence of a small amount of isobutene in the feed greatly accelerated these transformations and increase yields to the pentane isomers. The primary reactions were apparently acid-catalyzed, with the role of Pd confined to activity maintenance. The mildly fluorided zeolites in some cases proved more active overall than the parent zeolites H-mordenite and Pd-mordenite and were especially selective for the formation of the pentane isomers, apparently through a combination of disproportionation reactions and secondary alkylation reactions involving light hydrocarbon primary products.
A Note on Plasma Oscillations in a Magnetic Field

A concise derivation of the dispersion relation satisfied by longitudinal plasma oscillations of an electron gas in an external magnetic field at finite temperatures by a Green function method is given. The result derived is simpler and has a different structure than those obtained by Stephen and Zyryanov. The method used is a variant of that used by Nambu in his superconductivity theory as well as by Rajagopol and Rangannthan in their study of spin waves in a ferromagnetic electron gas. (auth)
Photogenic and self-induced epilepsy

Although a high percentage of patients with epileptic constitution have been found to be sensitive to photic stimulation in the laboratory, spontaneous photic epilepsy incident to light exposures under normal living conditions is quite rare. Seizures precipitated by self-indulged exposures are even more uncommon. A total of 52 cases of self-induced epilepsy have been reported in the world literature. While petit mal is the most frequent type of seizure, myoclonic jerks and grand mal seizures have been observed also. The literature is briefly reviewed, and the reflex nature, the genetic influence, and certain clinical aspects are discussed. Three cases of photogenic epilepsy, including 2 of the self-induced type, are reported.
Strongly charged polymer brushes

We have established phase diagrams for strongly charged polymer brushes as a function of salt concentration ns, chain grafting density and polymer backbone charge density. We show these are qualitatively different to the previously calculated weakly charged phase diagrams due to electrostatic stiffening and counterion condensation effects, the hallmarks of highly charged polymers such as DNA. Saturated phases arise where chains are locally or globally fully stretched. We show the salt dependence of brush height H depends on the form of the persistence length lp. In good agreement with experiment, we find H ~ ns−1/3 at higher salt concentrations if a linear relation between lp and Debye length is assumed.