cssi/SciSciGPT-SciSciNet huggingface dataset:
Developing the Problem-Posing Abilities of Prospective Elementary and Middle School Teachers

This chapter describes the results of an exploratory study incorporating problem posing in a mathematics content course for prospective elementary and middle school teachers. Problem posing was incorporated as problem generation (posing problems from a set of given information) and problem reformulation (posing problems related to a given problem). The content coverage of the course included problem solving, data analysis and probability, discrete mathematics, and algebraic thinking. Exposure to problem posing had two effects on those who posed the problems. First they began using more sophisticated problem reformulation techniques as the course progressed. Second, with regard to problem generation, participants developed efficient ways of posing problems when time constraints were imposed, and they developed greater aptitude for posing multi-step problems. The development of participants’ problem-posing abilities will be described in detail, and qualitative data will be presented to highlight participants’ views of the relationship between problem posing and school mathematics.
Chiral topological superconductor and half-integer conductance plateau from quantum anomalous Hall plateau transition

We propose to realize a two-dimensional chiral topological superconducting (TSC) state from the quantum anomalous Hall plateau transition in a magnetic topological insulator thin film through the proximity effect to a conventional $s$-wave superconductor. This state has a full pairing gap in the bulk and a single chiral Majorana mode at the edge. The optimal condition for realizing such chiral TSC is to have inequivalent superconducting pairing amplitudes on top and bottom surfaces of the doped magnetic topological insulator. We further propose several transport experiments to detect the chiral TSC. One unique signature is that the conductance will be quantized into a half-integer plateau at the coercive field in this hybrid system. In particular, with the point contact formed by a superconducting junction, the conductance oscillates between ${e}^{2}/2h$ and ${e}^{2}/h$ with the frequency determined by the voltage across the junction. We close by discussing the feasibility of these experimental proposals.
Binding of human serum high density lipoprotein apoprotein with aqueous dispersions of phospholipids.

Abstract The apoprotein separated from human serum lipoproteins of density 1.063 to 1.21 (HDL) by extraction with ethanol-ethyl ether (3:2) at -10° was shown to recombine in definite stoichiometric ratios either with the whole phospholipids of HDL or with the lecithin, phosphatidylethanolamine, and sphingomyelin fractions separated from the same lipoproteins. For the reaction, aqueous dispersions of phospholipids were obtained by sonic oscillation. HDL apoprotein maintained its binding property for phospholipids after acetylation, succinylation, reduction and alkylation, and treatment with neuraminidase, as well as in the presence of urea. The reconstituted protein-phospholipid complex acted as a substrate activator for the enzyme lipoprotein lipase obtained from chicken adipose tissue. This activity, previously reported for whole HDL, was not observed when either HDL apoprotein or phospholipids were used alone. The results are considered compatible with the concept that HDL is made of apoprotein subunits held by lipid bridges.
Controller Design with Eigenvalue and Eigenvector Insensitivity to Parameter Variations

The problem of controller design with eigenvalue and eigenvector insensitivity to parameter variations is considered. A method is proposed for designing a state feedback gain which controls the actual eigenvalue and eigenvector sensitivities over the range of the parameter variations. Sufficient condition for the existence of the feedback gain is derived and discussed.
Murine Sarcoma and Leukemia Viruses: Assay Using Clonal Lines of Contact-Inhibited Mouse Cells

A continuous cell line of highly contact-inhibited cells (NIH/3T3) has been developed from NIH Swiss mouse embryo cultures. Its growth properties are similar to those of 3T3 and BALB/3T3. Although 3T3 is relatively insensitive to focus formation by murine sarcoma viruses, cloned lines of both NIH/3T3 and BALB/3T3 have been isolated that are highly sensitive to sarcoma virus focus formation and leukemia virus growth. The sensitivity and specificity are comparable to those found with primary embryo cells. MSV-transformed lines of NIH/3T3 have been obtained.
ATTITUDES OF PEDIATRICIANS TOWARD DAY CARE

This is a report of the attitudes expressed by 103 pediatricians in North Carolina toward the day care of children. They indicate a concentration of interest in the individual child and his health rather than on the broad community needs and problems in day care. There is more recognition of the needs and value of day care to the handicapped child in contrast to the normal child. However, the variety and spontaneity of many responses, and the willingness of the great majority of respondents to help in better development of day care seems to indicate interest of physicians in this growing field of child care and is being further explored.
Psychological interventions vs. Drugs in the treatment of panic

The comparative effectiveness of psychological interventions and pharmacologic treatments on panic attacks was examined for a composite group comprised primarily of individuals with a diagnosis of panic disorder or agoraphobia with panic attacks. This was accomplished utilizing a comprehensive approach which examined treatment termination, treatment success/failure, and treatment relapse as three criteria of treatment outcome. Treatment outcome studies were often inadequate to this task in that they did not report dropout or relapse data or utilized experimental designs which did not permit such analyses. Claims of superiority for psychological or pharmacologic interventions in the treatment of panic are premature. Nonetheless, behavioral therapies specifically developed to ameliorate panic have the highest success rates and lowest relapse rates. Behavioral treatments which target panic attacks have higher success rates than exposure-based treatments. Agoraphobic individuals with panic attacks have, in general, higher dropout rates and lower success rates than individuals with panic disorders without avoidance, regardless of the treatment utilized.
Comparison of viral ultrastructure and DNA banding patterns from the reproductive tracts of eastern and western hemisphere Chelonus spp. (Braconidae: Hymenoptera)

Abstract Viruses from the reproductive tracts of eastern hemisphere ( Chelonus near curvimaculatus ) and western hemisphere ( Chelonus insularis ) braconid endoparasitic wasps were studied. Both viruses appeared similar under negative staining, consisting of rod-shaped, enveloped virions. Efficient techniques were developed for extraction and fractionation of virus DNA. Both viruses had multipartite genomes, and at least 15 ( C. near curvimaculatus ) and 12 ( C. insularis ) different DNA size classes in each were observed after electrophoretic fractionation, respectively. The electrophoretic patterns of the DNA from the two species differed primarily in the higher molecular weight DNA forms. The results provide the necessary foundation for more extensive experiments on the effects of these viruses on the physiology of the wasps' larval hosts.
Vertically aligned and electronically coupled growth induced InAs islands in GaAs.

Multilayer, vertically coupled, quantum dot structures are investigated using layers composed of InAs islands grown by molecular beam epitaxy in the Stranski-Krastanov growth mode. Single, 2, 5, and 10 InAs island layers are investigated in which the 40 \AA{} high InAs islands are separated by 56 \AA{} GaAs spacer layers. The InAs islands are vertically aligned in columns and are pseudomorphic. Between 1 and 10 layers of islands, 8 K photoluminescence shows a 25% reduction in PL linewidth, and a peak shift of 92 meV to lower energy, while transmission electron and atomic force microscopy show the island size in different layers remains constant. These effects are attributed to electronic coupling between islands in the columns, and a simple coupling model is used to simultaneously fit the spectral peak position shift and the linewidth changes.
Identification of Amino Acid Residues Critical for Catalysis of Holliday Junction Resolution by Mycoplasma genitalium RecU

The RecU protein from Mycoplasma genitalium, RecUMge, is a 19.4-kDa Holliday junction (HJ) resolvase that binds in a nonspecific fashion to HJ substrates and, in the presence of Mn2+, cleaves these substrates at a specific sequence (5′-G/TC↓C/TTA/GG-3′). To identify amino acid residues that are crucial for HJ binding and/or cleavage, we generated a series of 16 deletion mutants (9 N- and 7 C-terminal deletion mutants) and 31 point mutants of RecUMge. The point mutations were introduced at amino acid positions that are highly conserved among bacterial RecU-like sequences. All mutants were purified and tested for the ability to bind to, and cleave, HJ substrates. We found the five N-terminal and three C-terminal amino acid residues of RecUMge to be dispensable for its catalytic activities. Among the 31 point mutants, 7 mutants were found to be inactive in both HJ binding and cleavage. Interestingly, in 12 other mutants, these two activities were uncoupled; while these proteins displayed HJ-binding characteristics similar to those of wild-type RecUMge, they were unable to cleave HJ substrates. Thus, 12 amino acid residues were identified (E11, K31, D57, Y58, Y66, D68, E70, K72, T74, K76, Q88, and L92) that may play either a direct or indirect role in the catalysis of HJ resolution.
The Impact of Morphological Stemming on Arabic Mention Detection and Coreference Resolution

Arabic presents an interesting challenge to natural language processing, being a highly inflected and agglutinative language. In particular, this paper presents an in-depth investigation of the entity detection and recognition (EDR) task for Arabic. We start by highlighting why segmentation is a necessary prerequisite for EDR, continue by presenting a finite-state statistical segmenter, and then examine how the resulting segments can be better included into a mention detection system and an entity recognition system; both systems are statistical, build around the maximum entropy principle. Experiments on a clearly stated partition of the ACE 2004 data show that stem-based features can significantly improve the performance of the EDT system by 2 absolute F-measure points. The system presented here had a competitive performance in the ACE 2004 evaluation.
Theophylline for Chronic Symptomatic Bradycardia in the Elderly

The treatment of choice for chronic, symptomatic bradycardia is the placement of a cardiac pacemaker. Individuals who refuse or cannot tolerate pacemaker insertion usually require pharmacologic therapy. Hydralazine, prazosin, anticholinergics, and sympathomimetic agents have been administered for this indication, but adverse effects and limited data hinder routine, long-term use. Theophylline has emerged as a reasonable alternative strategy. For the medical management of bradycardia in the elderly, the literature supports theophylline dosages between 400 and 600 mg/d (approximately 8 mg/kg/d) administered in divided doses. This dosage range should result in a steady-state serum concentration between 5 and 15 mg/L. While some investigators recommend potentially higher initial doses (up to 12 mg/kg/d), lower dosages are more appropriate in the elderly due to decreased theophylline clearance. Initial dosage titration may be indicated and prolonged therapy is expected on the basis of the common etiologies of bradycardia in this patient group. Patient specifics such as altered theophylline metabolism (e.g., smoking), drug interactions (e.g., ciprofloxacin), and concomitant disease states (e.g., hepatic disease, heart failure) should always be considered in theophylline dosage recommendations. Clinicians should adjust the theophylline dose on the basis of patient response, including heart rate and clinical symptomatology, as well as measurement of occasional theophylline concentrations, if deemed appropriate. Theophylline should be avoided in the bradycardia-tachycardia manifestations of sick sinus syndrome or when ventricular ectopy is frequent. Additional investigation will further define the role of theophylline in elderly patients with chronic, symptomatic bradycardia.
Elastic-plastic analysis of deformation induced by thermal stress in eutectic composites: III. thermal-cycling damage

The analytical method of part I is used to calculate the dependence of composite deformation on cyclic, geometric, and constituent deformation parameters. The calculated hysteresis loop of matrix stress versus temperature caused by plastic deformation stabilizes after a few cycles so that a steady-state plastic compression-tension fatigue results when no external stress is present. In most cases plastic shakedown is thereby precluded. The calculated stresses can be much different from those predicted by existing elasticity analyses. Even when the matrix plasticity is fairly small, the elasticity approaches at best predict the range of, but not the extrema in, component stresses. Failure of a cycled eutectic composite may be due to any of several causes, and all must be considered in any evaluation.
Surface-supported bilayers with transmembrane proteins: role of the polymer cushion revisited.

Protein lateral mobility in surface-supported bilayers is often much lower than the mobility of the lipids. In the present study we explore whether the incorporation of a PEG cushion between the bilayer and the substrate increases the lateral mobility of transmembrane proteins in bilayers produced via directed assembly, a method based on Langmuir−Blodgett deposition techniques. In our experiments, the PEG cushions were incorporated by adding PEG lipids to the protein/lipid monolayer at the air/water interface, at the first step of bilayer assembly. The protein and lipid mobilities in 160 different bilayers, with various PEG molecular weights and PEG lipid concentrations, were measured and compared. We found that the measured diffusion coefficients do not depend on the PEG molecular weight or the PEG lipid concentration and are very similar to the values measured in the absence of PEG. Therefore, contrary to our expectations, we found that a PEG cushion does not necessarily increase protein mobility, sugge...
A cobalt complex that selectively disrupts the structure and function of zinc fingers

Zinc finger domains are structures that mediate sequence recognition for a large number of DNA-binding proteins. These domains consist of sequences of amino acids containing cysteine and histidine residues tetrahedrally coordinated to a zinc ion. In this report, we present a means to selectively inhibit a zinc finger transcription factor with cobalt(III) Schiff-base complexes. 1H NMR spectroscopy confirmed that the structure of a zinc finger peptide is disrupted by axial ligation of the cobalt(III) complex to the nitrogen of the imidazole ring of a histidine residue. Fluorescence studies reveal that the zinc ion is displaced from the model zinc finger peptide in the presence of the cobalt complex. In addition, gel-shift and filter-binding assays reveal that cobalt complexes inhibit binding of a complete zinc finger protein, human transcription factor Sp1, to its consensus sequence. Finally, a DNA-coupled conjugate of the cobalt complexes selectively inhibited Sp1 in the presence of several other transcription factors.
Selecting pre-screening items for early intervention trials of dementia—a case study

Our goal was to review and extend statistical methods for discriminating between normal subjects and those with dementia or cognitive impairment. We compared six different methods to one constructed by expert opinion, in their brevity and predictive power. The methods include logistic regression and neural networks, with standard and least absolute shrinkage and selection operator (LASSO) variable selection, as well as decision trees with and without boosting. These methods were applied to the baseline data of a subgroup of subjects in a dementia study, using their screening interview items to predict their clinical diagnosis of normal or non-normal (cognitively impaired or demented). The derived models were then validated on a different subgroup of subjects in the same study who had the screening and clinical diagnosis two to five years later. Performance of different models was compared based on their sensitivity and specificity in the validation sample. Generally, the six statistical methods performed slightly to moderately better than the expert-opinion model. Neural networks generally performed better than the logistic and decision tree models. LASSO improved the performance of logistic and neural network models, but it eliminated few input variables in the neural network. The single decision tree performed at least as well as the standard logistic model, and with fewer items, making it an attractive pre-screening tool. Using the boosting option for decision trees did not substantially improve the performance. We recommend that for each situation, different methods of classification should be attempted to obtain optimal results for a given purpose.
Properties of fermion mixings in intersecting D-brane models

Abstract We consider the Yukawa couplings for quarks and leptons in the context of Pati–Salam model using intersecting D-brane models where the Yukawa coupling matrices are rank one in a simple choice of family replication. The CKM mixings can be explained by perturbing the rank 1 matrix using higher order terms involving new Higgs fields available in the model. We show that the near bi-large neutrino mixing angles can be naturally explained, choosing the light neutrino mass matrix to be type II seesaw dominant. The predicted value of U e 3 is in the range ≃ 0.05 – 0.15 . In the quark sector, V c b is naturally close to the strange/bottom quark mass ratio and we obtain an approximate relation V u b V c b ≃ ( m s / m b ) 2 V u s . The geometrical interpretations of the neutrino mixings are also discussed.
Ribosylzeatin and zeatin in tobacco crown gall tissue

Cytokinins were extracted from two cultures of tobacco crown gall tumor tissue: an unorganized tissue and a teratoma which produced leafy shoots. On Sephadex LH-20 column chromatography, extracts of both types of tissue yielded two peaks of cytokinin activity with elution volumes similar to ribosylzeatin and zeatin. Ribosylzeatin and zeatin were detected and quantified by coupled gas chromatography - mass spectrometry selected ion monitoring (GC/MS SIM), comparable quantities being found in the two extracts. Full mass spectral evidence for the presence of ribosylzeatin in both tissues was obtained. No evidence was found for the presence of N(6)-(Δ(2)-isopentenyl)adenosine (i(6)Ade) or N(6)-(Δ(2)-isopentenyl)adenine (i(6)Ade) although these compounds have been reported to occur in cytokinin-habituated tobacco callus tissues.
Synthetic scotophobin-mediated passive transfer of dark avoidance.

A CHEMICAL rather than an electrical mode of long term storage of learned behavioural information was first suggested more than 20 yr ago1. Experimental means for studying the nature of the storage molecule (by passive transfer from a trained donor to a naive recipient) were suggested by some provocative experiments2,3. Jacobson et al.3 claimed that the causative factor was RNA. RNA, however, prepared similarly by others but analysed for impurities by a more sensitive method, was clearly contaminated with peptides4. Brain RNA labelled with 32P and injected intraperitoneally (Jacobson et al.'s injection route) does not cross the blood-brain barrier5 although it is well known that peptides do get across. The inconsistency of activity of RNA fractions prepared by different investigators6 hinted that: (a) RNA might be acting as a carrier for the true active compound and (b) the binding between RNA and such an active compound might be labile.
Feedback stabilization of snap-through buckling in a preloaded two-bar linkage with hysteresis ☆

Abstract We study a linearly damped preloaded two-bar linkage that exhibits hysteresis due to the presence of multiple attracting equilibria. The dynamics at the unstable equilibrium, through which a snap-through buckle occurs, are not linearizable due to a solution-dependent singularity. We stabilize the unstable equilibrium using two distinct non-linear controllers. The feedback-linearization controller requires knowledge of the linkage parameters, whereas the robust version of the intrinsic non-linear proportional-derivative controller requires only an upper bound on the stiffness.
Formation of epoxide and quinone protein adducts in B6C3F1 mice treated with naphthalene, sulfate conjugate of 1,4-dihydroxynaphthalene and 1,4-naphthoquinone

Naphthalene (NA) is metabolically activated to the reactive intermediates, naphthalene oxide (NO) and naphthoquinones. To investigate the role of circulating reactive metabolites in NA toxicity, the half-life of NO was examined. The in vitro half-life of NO in both whole blood and plasma was 10 min. Detectable levels of NO were seen in perfusate leaving the isolated perfused liver of B6C3F1 mice infused with 10 μmol/h NA. Identification of protein sulfhydryl adducts in NA-exposed mice (50 and 100 mg/kg, IP, 24h) revealed a predominance of quinone adducts in liver, lung, kidney, red blood cells and brain. The epoxide adduct predominated in plasma protein. Administration of the sulfate conjugate of 1,4-dihydroxynaphthalene (NHQS) (100 mg/kg) resulted in formation of naphthoquinone protein sulfhydryl adducts in lung, liver and kidney. Administration of 1,4-naphthoquinone (NQ) (5mg/kg) produced NQ adducts in liver, lung, kidney, plasma and brain.
The dynamical interaction of a newly formed protostar with infalling matter - The origin of interstellar grains

Physical processes involving dust grains are studied during the collapse of a dense interstellar cloud. The formation of a central protostar can, via radiation pressure for massive stars or by the generation of protostellar winds for less massive stars, provide a means of supporting the infalling material against accretion onto the protostar. A thin shell is formed, bounded at its inner surface by melting of the grains and compressed by the ram pressure of the infalling material. We show that for sufficiently large protostellar luminosities, produced by stars in excess of approx.5 M/sub sun/, the grain shell will move outward and become convectively unstable. Evaporation, shattering, nucleation, and accretion processes all play a role in determining the emergent grain distribution. For protostars of lower mass, disk formation may be important, and a protostellar wind can expel the smaller particles into the interstellar medium. The emergent grain size spectrum is found to be bimodal, with a predominance of small particles.This scenario yields a tentative explanation for the origin of the bulk of the mass in interstellar grains, because it provides a means of increasing the number of grains for a given total mass. Although the initial refractory cores may be producedmore » during mass loss from evolved stars, by recycling grains through successive protostellar phases where accretion, evaporation, nucleation, and shattering play a role, we are able to account quantitatively for the tatal mass in grains, the relatively large number of small particles required to explain the observed far-ultraviolet extinction, and in a more qualitative manner for the apparent spatial variability in the far-ultraviolet extinction law. (AIP)« less
E2F1 in neurons is cleaved by calpain in an NMDA receptor-dependent manner in a model of HIV-induced neurotoxicity

The transcription factor E2F1 activates gene targets required for G1 -S phase progression and for apoptosis, and exhibits increased expression levels in neurons in several CNS diseases including HIV encephalitis, Alzheimer disease, and Parkinson's Disease. While E2F1 is known to regulate cell viability through activation of caspases, here we present evidence supporting the involvement of E2F1 in N-methyl-d-aspartate (NMDA) receptor-dependent, HIV-induced neuronal death mediated by calpains. Using an in vitro model of HIV-induced neurotoxicity that is dependent on NMDA receptor and calpain activation, we have shown that cortical neurons lacking functional E2F1 are less susceptible to neuronal death. In addition, we report that neuronal E2F1 is cleaved by calpain to a stable 55-kiloDalton fragment following NR2B-dependent NMDA receptor stimulation. This cleavage of E2F1 is protein conformation-dependent and involves at least two cleavage events, one at each terminus of the protein. Intriguingly, the stabilized E2F1 cleavage product is produced in post-mitotic neurons of all ages, but fails to be stabilized in cycling cells. Finally, we show that a matching E2F1 cleavage product is produced in human fetal neurons, suggesting that calpain cleavage of E2F1 may be produced in human cortical tissue. These results suggest neuronal E2F1 is processed in a novel manner in response to NMDA receptor-mediated toxicity, a mechanism implicated in HIV-associated neurocognitive disorders pathogenesis as well as several other diseases of the CNS. After crossing the blood-brain barrier, HIV-infected monocytes differentiate into macrophages and release excitotoxins and inflammatory factors including glutamate into the brain parenchyma (1). These factors stimulate neuronal N-Methyl-d-aspartate (NMDA) receptors (2), causing calcium influx (3) and subsequent activation of the cysteine protease calpain (4). Activated calpain cleaves multiple substrates including E2F1, producing a stabilized protein fragment with truncations at the N- and C-terminus (5). Calpain-cleaved E2F1 may contribute to calpain-mediated neuronal damage observed in NMDA receptor-mediated neurotoxicity (6).
Combating neurodegenerative disease with chemical probes and model systems

The disheartening results of recent clinical trials for neurodegenerative disease (ND) therapeutics underscore the need for a more comprehensive understanding of the underlying disease biology before effective therapies can be devised. One hallmark of many NDs is a disruption in protein homeostasis. Therefore, investigating the role of protein homeostasis in these diseases is central to delineating their underlying pathobiology. Here, we review the seminal role that chemical biology has played in furthering the research on and treatment of dysfunctional protein homeostasis in NDs. We also discuss the vital and predictive role of model systems in identifying conserved homeostasis pathways and genes therein that are altered in neurodegeneration. Integrating approaches from chemical biology with the use of model systems yields a powerful toolkit with which to unravel the complexities of ND biology.
Point of view. Occupational safety and health: The years ahead

Many lawyers, scientists, lawmakers, and industrial and labor leaders have expressed concern about the escalating problems in dealing with occupational safety and health. This paper discusses problems, explores the ways in which the current administration may deal with the issues, and suggests a course of action.
The Allende meteorite: evidence for a new cosmothermometer based on Ti 3+ /Ti 4+

Applications of the mineral thermodynamic condensation sequence to assemblages in Ca–Al–Ti-rich inclusions in the Allende meteorite suggest that the total amount of titanium and Ti3+ contents of aluminous clinopyroxenes (fassaites) are temperature sensitive and that the ratio Ti3+/Ti4+ may be used as a qualitative cosmothermometer.
Partial orderings of fixed finite dimension: Model companions and density

The model companions of the theories of n -dimensional partial orderings and n -dimensional distributive lattices are found for each finite n . Each model companion is given as the theory of a structure which is specified. The model companions are model completions only for n = 1. The structure of the model companion of the theory of n -dimensional partial orderings is a lattice only for n = 1. Each of the model companions is seen to be finitely axiomatizable, and a set of basic formulas, each of which is existential, is specified for each model companion. Finally a topolo-gically natural notion of dense n -dimensional partial ordering is introduced and shown to have a finitely axiomatizable undecidable theory. In this paragraph we shall define the notion of model companion (cf. [4]) and indicate the way in which we shall demonstrate that one theory is the model companion of another in this paper. For T and T * theories in a common language, T * is called a model companion of T if and only if the following two conditions are satisfied: first, Tand T * are mutually model consistent, which means that every model of either is embeddable in some model of the other; secondly, T * is model complete, which means that if and are both models of T * and is a substructure of , then is an elementary substructure of . A definition of model completion may be obtained by strengthening the notion of model companion to also require that T * admit elimination of quantifiers. In all of our examples the model companion will have only one countable model. Although the ℵ 0 -categoricity of the model companions follows from Saracino [8], we give specific proofs since these proofs fit so naturally in our analyses.
Functional identity of catalytic subunits of acetylcholinesterase

Abstract 11 S acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) from the electric eel Electrophorus electricus essentially consists of four catalytic subunits which appear to be identical structurally but to be assembled with slight asymmetry. During isolation and storage of the enzyme, proteolysis cleaves a portion of the subunits into major fragments containing the active site and minor fragments containing no active sites without change in the enzyme molecular weight. A previous report (Gentinetta, R. and Brodbeck, U. (1976) Biochim. Biophys. Acta 438, 437–448) indicated that the intact and the fragmented subunits reacted with diisopropylfluorophosphate at different rates and that the reaction rate in the presence of excess phosphorylating agent was not strictly first order. Those findings could not be reproduced in this report. Intact and fragmented subunits were observed to react at the same rate with diisopropylfluorophosphate. In addition, the overall reaction kinetics both of 11 S and 18 S plus 14 S acetylcholinesterase were found to be strictly first order in the presence of an excess of diisopropylfluorophosphate throughout the course of reaction. These results are consistent with several previous reports that only one type of active site can be detected in acetylcholinesterase. The proteolysis which fragments a portion of the catalytic subunit has no apparent effect on the catalytic properties of the enzyme.
Stereospecific high-performance liquid chromatographic analysis of hesperetin in biological matrices.

Abstract A method of analysis of hesperetin (+/−-3,5,7-trihydroxy-4′-methoxyflavanone) in biological fluids is necessary to study the kinetics of in vitro and in vivo metabolism and tissue distribution. A simple high-performance liquid chromatographic method was developed for simultaneous determination of hesperetin enantiomers in rat serum, and rat and human urine. Serum and urine (0.1 ml) were precipitated with cold acetonitrile after addition of the internal standard, 7-methoxycoumarin. Separation was achieved on a Chiralpak AD-RH column with UV detection at 298 nm. The calibration curve was linear ranging from 0.5 to 100 μg/ml for each enantiomer. The mean extraction efficiency was >98%. Precision of the assay was
Relative Importance of Factors concerning a Contemporary Artist's Background

This study investigated the importance of different factors or variables used by relatively naive people in judging the merits of a graphic artist. Subjects were university students who responded to a questionnaire in which they ranked 12 factors on importance in deciding the merit of an hypothetical artist. The analysis indicated that the rankings were not random and that ‘work shown in a museum’ was clearly the most persuasive indicator of merit. The ability of an artist to exercise some control over the perception of his work is discussed.
Superconducting electronics: current status and future prospects

Abstract Superconducting electronics can provide devices and circuits with properties not obtainable for any other known technology; i.e. very low loss, zero frequency-dispersion signal transmission lines, very high Q -value resonators and filters, and quantum limited electromagnetic sensors for radiation from d.c. through the millimetre wave region and into the infrared. The impact of the newly discovered high temperature superconducting materials with transition temperatures in excess of 90 K could revolutionize electronic technology as it would bring these very interesting properties and device behaviour to an operating temperature where: 1, refrigeration requirements are greatly reduced; and 2, where hybrid semiconductor-superconductor circuits can be built which make use of the best features of each technology. In addition, new phenomena might be discovered in these new materials which could impact electronic technology.
Differing effects of cadmium on two varieties of cottonwood Populus deltoides Bartr.

Abstract Two varieties of cottonwood, Populus deltoides Bartr., were grown under greenhouse conditions in soil treated with differing amounts of cadmium chloride to compare various parameters of growth and uptake. Concentration levels of 5, 25, 100 and 200 μg Cd/g soil were established with a control treatment in individual 17·8 cm diameter plastic pots filled with a 1:1 mixture of Grantsburg silt loam and ‘Perlite’. Plants were germinated and grown through one growing season of 14 weeks. Following harvest, cadmium concentrations were determined in leaf, stem and root tissue by atomic absorption spectrophotometry. Leaf, stem and root biomass, height and percent survival of the seedlings were also determined. The two varieties studied were found to differ significantly in cadmium allocation to roots and stems and in percent survival. Leaf and root biomass and cadmium concentration of leaf tissue were found to be predominantly controlled by the cadmium level of the soil but were not variety-dependent. Stem biomass and height were variety-dependent but did not differ as a result of soil cadmium concentration.
Optimal sampling strategies in the coupon collector’s problem with unknown population size

In doing a six-sigma analysis of a process one must first determine the set of possible factors that potentially drive the response of interest. This stage of the the work, known as process mapping, is time consuming. Spending too much time on it wastes investigators and employees time. Yet, spending too little time may result in failing to uncover important factors that drive the process. We model this situation as a general coupon collector’s problem with N distinct coupons, where the exact value of N is not known. Our objective is to devise effective strategies to minimize the total cost incurred due to sampling in addition to the cost of unidentified coupons when the collector stops sampling. We propose a policy based on an asymptotic analysis when N is large and prove that the proposed policy is asymptotically optimal. We also illustrate the effectiveness of this policy with numerical experiments.
In Situ Hvem Study of Ion Irradiation-Induced Grain Growth in Au Thin Films

In situ observations of 1.5 MeV Xe/sup +/ ion irradiated Au films at room temperature and at 150/degree/C reveal the evolution of grain growth: the average grain size increases by the mechanisms of grain boundary migration and grain coalescence. 10 refs., 4 figs.
Controlling the Charge State and Redox Properties of Supported Polyoxometalates via Soft Landing of Mass-Selected Ions

We investigate the controlled deposition of Keggin polyoxometalate (POM) anions, PMo12O403– and PMo12O402–, onto different self-assembled monolayer (SAM) surfaces via soft landing of mass-selected ions. Utilizing in situ infrared reflection absorption spectroscopy (IRRAS), ex situ cyclic voltammetry (CV), and electronic structure calculations, we examine the structure and charge retention of supported multiply charged POM anions and characterize the redox properties of the modified surfaces. SAMs of alkylthiol (HSAM), perfluorinated alkylthiol (FSAM), and alkylthiol terminated with NH3+ functional groups (NH3+SAM) are chosen as model substrates for soft landing to examine the factors that influence the immobilization and charge retention of multiply charged anionic molecules. The distribution of charge states of POMs on different SAM surfaces is determined by comparing the IRRAS spectra with vibrational spectra calculated using density functional theory. In contrast with the results obtained previously fo...
The accuracy of radionuclide ventriculography in the analysis of left ventricular ejection fraction

Abstract To assess the reliability of using ejection fraction values derived from gated blood pools scans as a way to classify patients, we reviewed 76 radionuclide studies. Each study was processed in 10 different ways (varying of fixed left ventricular region of interest in association with 5 different backgrounds), and compared with contrast ventriculograms performed within one week of the radionuclide study. Correlation values with contrast results varied from 0.76 to 0.94 (mean 0.84 ± 0.06, ± 1 SD), and linear fit slopes varied from 0.39 to 0.90 (mean 0.75 ± 0.15). Based on contrast results, patients were divided first into four groups (severely reduced, reduced, normal, and high ejection fractions). Predictive accuracy of the radionuclide estimates for these four groups was poor, ranging from 0.39 ± 0.08 to 0.82 ± 0.06%. Sensitivity was somewhat better (range 0.53 ± 0.11 to 0.78 ± 0.08%), and specificity better yet (0.78 ± 0.08 to 0.95 ± 0.02%). The results were better with techniques resulting in higher correlation values, and further improved when patients were regrouped into two populations (normal or reduced), though 90% of subjects were correctly identified only when correlation values exceeded 0.90. We conclude that care must be taken in the identification of patients using radionuclide angiography who have normal and abnormal left ventricular function; it can be done with confidence only when linear fits with contrast ventriculographic results have high correlation coefficients. Stratification attempts should be reduced to a minimum, as multiple population subgroups result in substantial patient mislabeling.
Accelerating the Pace of Protein Functional Annotation With Intel Xeon Phi Coprocessors

Intel Xeon Phi is a new addition to the family of powerful parallel accelerators. The range of its potential applications in computationally driven research is broad; however, at present, the repository of scientific codes is still relatively limited. In this study, we describe the development and benchmarking of a parallel version of ${\mmb e}$ FindSite, a structural bioinformatics algorithm for the prediction of ligand-binding sites in proteins. Implemented for the Intel Xeon Phi platform, the parallelization of the structure alignment portion of ${\mmb e}$ FindSite using pragma-based OpenMP brings about the desired performance improvements, which scale well with the number of computing cores. Compared to a serial version, the parallel code runs 11.8 and 10.1 times faster on the CPU and the coprocessor, respectively; when both resources are utilized simultaneously, the speedup is 17.6. For example, ligand-binding predictions for 501 benchmarking proteins are completed in 2.1 hours on a single Stampede node equipped with the Intel Xeon Phi card compared to 3.1 hours without the accelerator and 36.8 hours required by a serial version. In addition to the satisfactory parallel performance, porting existing scientific codes to the Intel Xeon Phi architecture is relatively straightforward with a short development time due to the support of common parallel programming models by the coprocessor. The parallel version of ${\mmb e}$ FindSite is freely available to the academic community at www.brylinski.org/efindsite .
Reinforcement learning modulates preparatory states of cognitive flexibility

Cognitive control is the foundation of goal-directed, intentional behaviour. Adaptive cognitive control involves switching and maintaining cognitive operations in accordance with ongoing task deman...
ViewCube: a 3D orientation indicator and controller

Literally hundreds of thousands of users of 2D computer-aided design (CAD) tools are in the difficult process of transitioning to 3D CAD tools. A common problem for these users is disorientation in the abstract virtual 3D environments that occur while developing new 3D scenes. To help address this problem, we present a novel in-scene 3D widget called the ViewCube as a 3D orientation indicator and controller. The ViewCube is a cube-shaped widget placed in a corner of the window. When acting as an orientation indicator, the ViewCube turns to reflect the current view direction as the user re-orients the scene using other tools. When used as an orientation controller, the ViewCube can be dragged, or the faces, edges, or corners can be clicked on, to easily orient the scene to the corresponding view. We conducted a formal experiment to measure the performance of the ViewCube comparing: (1) ArcBall-style dragging using the ViewCube for manual view switching, (2) clicking on face/edge/corner elements of the ViewCube for automated view switching and (3) clicking on a dedicated row of buttons for automated view switching. The results indicate that users prefer and are almost twice as fast at using the ViewCube with dragging compared to clicking techniques, independent of a number of ViewCube representations that we examined.
Selective Catalytic Dehydration of Tetrahydro-2-furanylmethanol Dehydration to 5-Methyl-2,3-dihydrofuran Over Large-pore Zeolites

The first example of selective synthesis 5-methyl-2,3-dihydrofuran (MDHF) via dehydration of tetrahydro-2-furanylmethanol (THFM) is described. This synthesis is accomplished in a single-step reaction and uses readily available catalysts consisting of sodium-exchanged faujasite zeolites (Na-X and Na-USY). The mechanism is hypothesized to involve a hydride shift in reactant THFM, which leads to MDHF. This is fundamentally different from the known ring-expansion pathway for hydrolysis, which synthesizes 3,4-dihydro-2H-pyran (DHP). The activity and selectivity of the catalysts to MDHF was observed to increase with time on stream, and decrease upon increasing reaction temperature. Upon increasing either the initial water content of the catalyst or water partial pressure during reaction, an increase in the MDHF/DHP ratio was observed. This last observation helps correlate the above-mentioned trends in the catalyst activity and selectivity with increased time on stream, since the dehydration reaction synthesizes water.
Clouds, Radiation, and the Diurnal Cycle of Sea Surface Temperature in the Tropical Western Pacific

Abstract The relationship among clouds, surface radiation flux, and the sea surface temperature (SST) of the tropical western Pacific Ocean over the diurnal cycle is addressed in the context of the Atmospheric Radiation Measurement (ARM) Program scientific objectives for the tropical western Pacific Ocean. An understanding of the relationship between clouds and SST on a variety of time and space scales is needed to understand fully the cloud-radiation feedback in the tropical oceans and the maintenance of the warm pool. Here the diurnal cycle is emphasized. Data from the TOGA COARE Intensive Observation Period is examined and interpreted using an ocean mixed layer model that includes a parameterization of the “skin” temperature, explicit salinity, a surface beat budget that includes the sensible heat flux associated with rain, and the contribution of rain to the surface momentum flux. Using a mix of modeling and observations, three different case studies are examined in detail: clear and calm, clear and w...
Turbulent Dynamos and Magnetic Helicity

It is shown that the turbulent dynamo alpha-effect converts magnetic helicity from the turbulent field to the mean field when the turbulence is electromagnetic while the magnetic helicity of the mean-field is transported across space when the turbulence is elcetrostatic or due to the elcetron diamagnetic effect. In all cases, however, the dynamo effect strictly conserves the total helicity expect for a battery effect which vanishes in the limit of magnetohydrodynamics. Implications for astrophysical situations, especially for the solar dynamo, are discussed.
A miniaturized parallel analyses platform for rapid electrochemical discoveries of microbial activities

We report a nine-well MEMS-based parallel analyses platform for testing electricity generation capacity of eight microbial consortia, which provides high throughput characteristics for bacterial electrogenic screening. The presented device features independent fluidic access to each analysis unit allowing for long term analysis ability without contamination from chamber to chamber during operation. The device contains vertically stacked 57μL anode/cathode chambers separated by a proton exchange membrane (PEM) and each device component is thermally assembled without mechanical supporting frames/bolts/nuts. This device will create a compact screening system individually addressable for identification and characterization of electrochemically active microbes.
EFFECT OF RATING INCONSISTENCY ON MIXED STANDARD SCALES

To investigate possible differential effects of consistent and inconsistent ratings, 100 college students rated their instructors on 7 dimensions using a mixed-standard scale format. Dimensional means for consistent ratings were generally higher than those for inconsistent ratings. Consistent ratings were also more strongly related to an over-all evaluation of the instructor. It was recommended that more attention be given the freqency of inconsistent ratings in research on mixed-standard scales.
Contesting Citizenship in Urban China: Peasant Migrants, the State, and the Logic of the Market

Post-Mao market reforms in China have led to a massive migration of rural peasants toward the cities. Officially denied residency in the cities, the over 80 million members of this "floating population" provide labor for the economic boom in urban areas but are largely denied government benefits that city residents receive. In an incisive and original study that goes against the grain of much of the current discussion on citizenship, Dorothy J. Solinger challenges the notion that markets necessarily promote rights and legal equality in any direct or linear fashion.