cssi/SciSciGPT-SciSciNet huggingface dataset:
Transient species produced by the catalytic decomposition of acetone in a mass spectrometer

The catalytic decomposition of acetone over Pt has been studied in a research mass spectrometer over the pressure range of from 10 −2 to 1 Torr and over the temperature range of from 273° to 1673°K. Two negative ions, CH 3 − and CH 3 COCH 2 − , and two free radicals, CH 3 and CH 3 COCH 2 , were observed in high concentrations in the gas phase during the course of the decomposition reaction. The principal stable products observed were CO and CH 4 . This investigation shows that the CH 3 − ion reacts with acetone to produce CH 4 . As far as can be judged from the experimental data, the CH 3 COCH 2 − is not involved in the main decomposition reaction, but rather is formed by surface ionization of the corresponding free radical. Each of the free radicals appeared to be produced by a different elementary reaction. CH 3 probably resulted from the initial decomposition reaction on the surface, whereas CH 3 COCH 2 was formed by a subsequent reaction of CH 3 with acetone. By generalizing from the data collected, the first two steps in the decomposition reaction are specified. On this basis, CO is proposed to result from the first step of the reaction which involves one acetone molecule. Attention is drawn to the fact that in this system free radicals and negative ions can lead to the same stable products. The decomposition reaction is heterogeneous because the observed activation energy of 34.4 kcal/mole of acetone is about one-half of that required for the homogeneous reaction. The present results are not inconsistent with a free radical chain mechanism for the homogeneous decomposition of acetone. An attempt is made to estimate the conditions under which appreciable concentrations of ions on catalytic surfaces might be expected. This is done by treating a typical catalytic reaction from a point of view of the energetics involved.
TRANSCATHETER AORTIC VALVE IN VALVE REPLACEMENT FOR DEGENERATIVE AORTIC BIOPROSTHESIS: INITIAL RESULTS FROM THE STS/ACC TRANSCATHETER VALVE THERAPY REGISTRY

Transcatheter aortic valve-in-valve replacement (ViV-TAVR) is a promising treatment modality for patients with degenerated aortic valve bioprosthesis. We evaluated the outcomes of ViV-TAVR in current US clinical practice. In-hospital outcomes of all patients who underwent ViV-TAVR using the
AMELOBLASTOMA POTENTIAL OF FOLLICULAR CYSTS.

Abstract One hundred eight cases of ameloblastoma definitely associated with follicular cysts and/or impacted tooth follicles were compiled from a review of the literature and a study of unpublished cases. A marked reduction in the prevalence of such cases occurred after the age of 30. The evidence presented supports the hypothesis that the potential for forming an ameloblastoma is lost with the transition of odontogenic epithelium to squamous epithelium in impacted tooth follicles and/or follicular cysts as the patient grows older.
Leaf Resistance in Succulent Plants

REPORTS in the literature indicate or suggest that the stomata of succulent plants open in the dark and close in the light. This conclusion is based on direct observations1, measurements of diffusion with a porometer2, and inference3. Nishida2 reported nocturnal stomatal opening in several succulent species, but diurnal opening in others. Thick leaves, few stomata, and small stomatal openings make measurements of the stomatal aperture and subsequent determinations of leaf resistance difficult. The innovation of a resistance hygrometer by Wallihan4 and van Bavel et al.5 allowed the precise determination of leaf resistance to water vapour transfer in succulent plants without the complications frequently encountered with other methods. Measurements of leaf resistance are based on changes in the resistance of a lithium chloride relative humidity sensor as water vapour diffuses from the leaf to the sensor. The sensor is calibrated with standard length tubes placed over a free water surface; thus the leaf resistance can be estimated in meaningful physical units (sec/cm)5. In this communication, we present data indicating the magnitude of leaf resistance to water vapour transfer in Kalanchoe blossfeldiana v. Poelln. in the light and dark. K. blossfeldiana was chosen because many investigators have used it as an experimental plant for dark carbon dioxide fixation studies6,7.
Sexual behavior of intact female rats after treatment with o,p'-DDT or p,p'-DDT.

Abstract Sexual behavior of adult, female rats was tested following treatment with o , p ′-DDT or with p , p ′-DDT during either diestrus or proestrus. Both chlorinated compounds decreased lordosis behavior, but o , p ′-DDT did so only after treatment on diestrus. p , p ′-DDT in contrast, decreased sexual behavior under all treatment conditions. o , p ′-DDT may have altered behavior by disrupting the estrous cycle while p , p ′-DDT had a major effect on the female's proceptivity and receptivity without modifying vaginal cyclicity. p , p ′-DDT disrupted sexual behavior at doses as low as 25 mg/kg while 100 to 200 mg/kg o , p ′-DDT were required. Since commercially prepared DDT contained a predominant proportion of p , p ′-DDT, these results suggest that many reproductive effects of DDT may have resulted from p , p ′-DDT rather than from o , p ′-DDT.
Cell-cycle control of c-myc but not c-ras expression is lost following chemical transformation

Cellular oncogenes are DNA sequences implicated in the genesis of cancer, but their functions in the transformation process are not understood. Our experiments provide data linking expression of two well-studied proto-oncogenes, c-myc and c-rasKi, to current knowledge of proliferation control and its perturbation by differentiation and chemical transformation. Growth stimulation of quiescent cells by serum elevates expression of the myc proto-oncogene in Balb/c 3T3 (A31) cells. In two chemically transformed A31 derivatives (BPA31 and DA31), c-myc expression is constitutive. The levels of c-myc mRNA in quiescent and growing transformed cells are nearly the same, and are only slightly elevated compared to the level found in growing A31 cells. By contrast, c-rasKi expression is cell-cycle-dependent in BPA31 cells. The relative abundance of c-rasKi mRNA begins to increase in mid- to late G0/G1. During terminal differentiation of teratocarcinoma stem cells (F9) into nonproliferating endoderm, relative mRNA abundance is diminished more markedly for c-myc than for c-rasKi. These results demonstrate that expression of the myc and rasKi proto-oncogenes is dependent upon the cellular growth state, and that growth control exhibits growth-factor-dependent, cell-cycle-timed oncogene expression. In the case of the BPA31 cells, c-myc is not rearranged, amplified, or overexpressed. However, the oncogene has lost its cycle-dependent regulation in the chemically transformed cells.
Plate perforation phenomena due to normal impact by blunt cylinders

Abstract An experimental program has been executed to measure the system parameters relevant to the normal impact of both rigid and deformable blunt cylinders against soft 2024-0 aluminum plates over the velocity range from 60–600 m/s, involving speeds just below and well above the ballistic limit. The data are compared to the predictions of a previously developed theory involving rigid/plastic constitutive relations for a five-stage penetration process that includes the dynamic response of the target by means of shear transmitted at the interface, but neglects plate bending. Force histories, determined by a special measurement technique, were found to be in good agreement with predicted values although subject to a significant uncertainty resulting from base line shift induced by temporary circuit interruption and by spikes attributed to elastic wave action. Similarly, measured strains agreed well with theory within the range of expected experimental errors. Surprisingly excellent correlation considering the relative simplicity of the model was also noted for other parameters, including the terminal velocity of the projectile, plate deformation and plug diameters. The assumption of a uniform strain field inherent in the theoretical development was generally verified, as well as the confinement of shear action to a narrow zone near the crater. Inclusion in the analysis of the shearing response of the target improved the correlation, but even better coincidence would be achieved upon addition of the target bending resistance to the theoretical model.
Reflexive Binormal Operators

Abstract This paper initiates a study of the problem of which binormal operators on a Hilbert space are reflexive. For a certain important class of binormal operators a simple measure-theoretic characterization is given for reflexivity.
Effect of hexafluoroisopropylidene on perfluorocyclobutyl aryl ether copolymer solution behavior in supercritical CO2 and propane

High-pressure phase behavior data reported here demonstrate the nuanced impact fluorine exerts on polymer solubility in supercritical fluid solvents. Copolymers are used that contain a perfluorocyc...
Effects of Testosterone Propionate on Female Roller Canaries under Complete Song Isolation

ConclusionThe administration of testosterone propionate to normal adult female roller canaries under conditions of complete song isolation brings forth male-like song in approximately 15 days after first administration, and thus substantiates previous theories.34567
Influence of sex hormones on mucopolysaccharide synthesis of swine arteries.

Summary The objectives of this investigation were to compare mucopolysaccharide (MPS) metabolism of aorta, pulmonary, and coronary vessels from swine and to determine influence of sex hormones on vascular MPS synthesis in vitro . The rate of MPS synthesis, determined by [ 35 S]sulfate incorporation, was dependent both on origin of arterial tissue and hormonal influence. Coronary arteries incorporated [ 35 S]sulfate at a significantly higher rate than pulmonary arteries or aortas. Aortas and coronary arteries from spayed females had a greater rate of [ 35 S]sulfate incorporation than the corresponding vessels from the intact females. The pulmonary arteries from males incorporated [ 35 S]sulfate at a greater rate than those from either intact or spayed females. 17 β -Estradiol added to the incubation media reduced the rate of [ 35 S] uptake by the coronary arteries from males and females, yet increased the rate in aortas from females. Testosterone added to the incubation media reduced the rate of [ 35 S] sulfate uptake by the coronary arteries of males.
ROLE OF dATP THE INHIBITION OF NUCLEIC ACID SYNTHESIS IN ISOLATED NUCLEI: 129

Nucleic acid synthesis was measured in nuclei isolated from proliferating lymphoblast cell lines that had been incubated with deoxyadenosine (dAdo) plus deoxycoformycin (dCf). Both RNA and DNA synthesis were inhibited in nuclei that were isolated from a T-cell line, CEM, following treatment with dAdo and dCf. Conversely, there was no inhibition of either RNA or DNA synthesis in the nuclei isolated from a B-cell line, WI-L2, or a dAdo kinase-deficient mutant of the T-cell line which had been incubated with dAdo plus dCf. Nucleotide measurements in the three cell lines implied that the accumulation of dATP in the intact cell was necessary for the inhibition of nucleic acid synthesis in the isolated nuclei. Saturating concentrations of all the nucleoside triphosphate. precursors were present in the assays of the isolated nuclei. Thus, the inhibition of nucleic acid synthesis could not be explained by a depletion of nucleotide precursors following an inhibition of ribonucleotide reductase by dATP. After the isolation and washing procedure, no endogenous nucleotides could be detected in the isolated nuclei. The accumulation of dATP in the intact cell apparently damaged the ability of isolated nuclei to synthesize nucleic acids and this damage persisted even in the absence of dATP.
Behavioral Response of Two Subterranean Termites (Isoptera: Rhinotermitidae) to Vibrational Stimuli

Behavioral responses to vibrational stimuli were examined in two subterranean termite species, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar). Termites habituated to vibrational stimulation when in social groups, but failed to do so individually, indicating that habituation is a collective action. In assays on termite groups, both species demonstrated a similar pattern of behavioral responses to vibrational stimuli: evanescent cessation of activity and movement, followed by withdrawal from the vibration source. Groups of both species then gradually moved back toward the vibration source as a consequence of continuous exposure. However, it took a significantly shorter period for C. formosanus to return (57 s) to the test arena and to resume (80 s) normal foraging activities in the test arena compared with R. flavipes, which took 97 and 227 s, respectively, when exposed to the vibration frequency of 120 bmpm. High vibration frequency (240 bmpm) increased the time required to return (C. formosanus, 80 s; R. flavipes, 153 s) and to resume regular locomotion (C. formosanus, 186 s; R. flavipes, 263 s). Our experiments demonstrate that workers play a crucial part in adjusting groups of termites to distressful vibrations. Soldiers of R. flavipes demonstrated similar behavioral responses as workers, however, C. formosanus soldiers exhibited a transient positive response before withdrawal.
Computer assisted sphere packing in higher dimensions

A computer was used to help study the packing of equal spheres in dimension four and higher. A candidate for the densest packing in 4-space is described. The configuration of 24 spheres touching a central sphere in this packing is shown to be rigid, unlike the analogue in 3-space, in which the spheres can slide past each other. A system for interactively manipulating and visualizing such configurations is described.The Voronoi cell for a sphere is the set of points closer to its center than to any other sphere center in the packing. The packing density is the ratio of a sphere's volume to the average of the volumes of the Voronoi cells. A method of constructing Voronoi cells and computing their volumes is presented, which works in any dimension. Examples of Voronoi cell volumes are given.
Reply to “Comments on Accuracy of Raman lidar water vapor calibration and its applicability to long-term measurements” by Whiteman et al.

In a recent commentary paper, Whiteman et al. [Appl. Opt.50, 2170 (2011)APOPAI0003-6935] discussed the applicability of the hybrid calibration method described by Leblanc and McDermid [Appl. Opt.47, 5592 (2008)APOPAI0003-693510.1364/AO.47.005592] under certain circumstances. They propose to use multiple lamps or a scanning lamp instead of a single lamp at a fixed location, to improve this method. The revised method proposed by Whiteman et al. indeed improves the spatial characterization of the receiver illumination, but still does not reproduce the ideal case of an illumination configuration similar to that of the atmospheric water vapor measurement. Its implementation also increases the chances for system disruption and can potentially defeat the purpose of the method described in Leblanc and McDermid, namely, long-term stability.
A Mechanical Apparatus for Hands-On Experience with the Morse Potential

A simple pulley apparatus is described that gives the student hands-on experience with the Morse potential. Students develop an internalized sense of what a covalent bond would feel like if atoms in a molecule could be manipulated by hand. This kinesthetic learning enhances the student’s understanding and intuition of several chemical phenomena. Possible learning objectives for different levels of chemistry instruction (from high school through upper-division undergraduate physical chemistry) are discussed.
Ammonia photolysis and the greenhouse effect in the primordial atmosphere of the earth

Photochemical calculations indicate that in the prebiotic atmosphere of earth ammonia would have been irreversibly converted to N2 in less than 40 years if the ammonia surface mixing ratio were no more than 0.0001. However, if a continuous outgassing of ammonia were maintained, radiative-equilibrium calculations indicate that a surface mixing ratio of ammonia of 0.0001 or greater would provide a sufficient greenhouse effect to keep the surface temperature above freezing. With a 0.0001 mixing ratio of ammonia, 60% to 70% of the present-day solar luminosity would be adequate to maintain surface temperatures above freezing. A lower limit to the time constant for accumulation of an amount of nitrogen equivalent to the present day value is 10 my if the outgassing were such as to provide a continuous surface mixing ratio of ammonia of at least 0.00001.
A Checklist of Virginia Lichens

Abstract. A list of 598 taxa of lichen-forming, lichenicolous, and allied fungi has been compiled exclusively from specimens examined and verified by the authors or associated specialists. This list contains 190 potential state records for Virginia, and three species that have not previously been reported from North America: Arthonia anglica Coppins, Calvitimela talayana (Haugan & Timdal) Andreev, and Sphaerellothecium coniodes (Nyl.) Cl. Roux & Diederich.
Optimizing rotating gamma camera PET for brain imaging

Several acquisition geometries were investigated to optimize coincidence count rates and coincidence/singles rate ratios for brain imaging on a rotating gamma camera PET system. Detection efficiency and singles count rate limits on these systems dictate that keeping unused singles from hitting the cameras should improve coincidence rates if radiotracer doses can be adjusted to match the singles detection efficiency of the system. Radius of rotation and camera field of view were adjusted within the constraints of patient positioning. Acquisitions were done with transaxial septa on a graded absorber, and with graded absorber alone. Phantoms included a Ge-68 pin source and an extended head-thorax phantom with F-18 solution. Coincidence detection efficiency was best for the absorber only, with a small radius of rotation. Coincidence/singles ratio was best for graded absorber with small radius of rotation and axial camera field limited to 27 cm. The septa yielded a slightly lower coincidence/singles ratio, but their reduction of scatter and restriction of incidence angle of detected photons (leading to higher spatial resolution) makes their use favorable.
Hollow Waveguide Gas Sensor for Mid-Infrared Trace Gas Analysis

A hollow waveguide mid-infrared gas sensor operating from 1000 cm-1 to 4000 cm-1 has been developed, optimized, and its performance characterized by combining a FT-IR spectrometer with Ag/Ag-halide hollow core optical fibers. The hollow core waveguide simultaneously serves as a light guide and miniature gas cell. CH-4 was used as test analyte during exponential dilution experiments for accurate determination of the achievable limit of detection (LOD). It is shown that the optimized integration of an optical gas sensor module with FT-IR spectroscopy provides trace sensitivity at the few hundreds of parts-per-billion concentration range (ppb, v/v) for CH-4.
Effects of neutrophils in rat luteal cells.

Ovarian function may be modulated by cells of the immune system. We have investigated the role of neutrophils (polymorphonuclear leukocytes) on rat luteal cell function. Activated neutrophils inhibited LH-sensitive cAMP accumulation, which was dependent on neutrophil cell number. At a concentration of 10(6) neutrophils/ml and 10(5) luteal cells/ml, LH-stimulated cAMP accumulation was inhibited by 50%. The inhibitory effect of activated neutrophils was reversed by superoxide dismutase (SOD) and catalase. LH-stimulated progesterone production was also inhibited by activated neutrophils. Progesterone production by 10(5) luteal cells was inhibited approximately 20% in the presence of 10(6) activated neutrophils, and this inhibition was blocked by SOD and catalase. Conditioned medium from activated neutrophils also produced inhibitory effects on LH-stimulated cAMP accumulation and progesterone production, which could be reversed by SOD and catalase. The phosphodiesterase inhibitor isobutylmethylxanthine had no...
Acid Rain Policymaking and Environmental Federalism: Recent Developments, Future Prospects

Acid rain controls are one of the more salient policy issues for contemporary environmental federalism. Agenda prominence, however, does not guarantee agreement on the components of a regulatory program. Depending on how many tons of emissions reduction one wants, when one wants them, and how one permits emitters to achieve compliance, a control program's costs can vary by billions of dollars annually. This article provides a summary of significant state and national policy initiatives as well as an examination of the barriers and incentives for such action.
Cardiovascular changes during classical conditioning in the squirrel monkey.

Changes in blood pressure (BP) and heart rate (HR) were classically conditioned in squirrel monkeys using light as the conditional stimulus, and electric shock as the unconditional stimulus. The transient (lasting less than 5 min) and sustained (maintained for a half-hour or more) changes in BP and HR in response to light-shock (LS) pairs and light alone (L) were measured while varying rates of presentation and shock intensity. LS presentation produced transient increases in both BP and HR. The magnitude of the change increased with shock intensity and decreased as stimulation rate increased. Transient changes in BP and HR in response to L presentation were induced by conditioning with LS. The conditioned transient response to L alone was greater when the LS conditioning period preceding it had greater shock intensity or slower presentation rate. Sustained changes in BP and HR were also produced by LS, the magnitude of which were directly related to the frequency of aversive stimulus presentation. Transient changes, in contrast, decreased in magnitude with more frequent presentation.
Supersymmetry as a cosmic censor

Here we investigate (U(1)j charged dilaton black holes in this context. The extreme solutions are shown to saturate the supersymmetry bound of N = 4, d = 4 supergravity, or dimensionally reduced superstring theory. Specifically, we have shown that extreme dilaton black holes, with electric and magnetic charges, admit supercovariantly constant spinors. The supersymmetric positivity bound for dilaton black holes is given by M & ~ (~Q~+ ~P~). This condition for dilaton black holes coincides with the cosmic censorship requirement that the singularities be hidden, as was the case for other asymptotically Bat static black-hole solutions. We conjecture that the bounds from supersymmetry and cosmic censorship will coincide for more general solutions as well. The temperature, entropy, and singularity of the stringy black hole are discussed in connection with the extreme limit and restoration of supersymmetry. The Euclidean action (entropy) of the extreme black hole is given by 2+~PQ~. We argue that this result is not altered by higher-order corrections in the supersymmetric theory. In the Lorentzian signature, quantum corrections to the effective on-shell action in the extreme black-hole background are also absent. When a black hole reaches its extreme limit, the thermal description breaks down. It cannot continue to evaporate by emitting (uncharged) elementary particles, since this would violate the supersymmetric positivity bound. We speculate on the possibility that an extreme black hole may "evaporate" by emitting smaller extreme black holes.
Navigating discourses in place in the world of Webkinz

Geosemiotics (Scollon and Scollon, 2003) frames this analysis of play, multimodal collaboration, and peer mediation as players navigate barriers to online connectivity in a children’s social network and gaming site. A geosemiotic perspective enables examination of children’s web play as discourses in place: fluidly converging and diverging interactions among four factors: (1) social actors, (2) interaction order, (3) visual semiotics, and (4) place semiotics. The video data are excerpted from an ethnographic study of a computer club for primary school-aged children in an afterschool program serving working-class and middle-class families in a US Midwest university community. Discourses of schooling in the computer room and Webkinz complicated children’s goal of coordinated game play and mutual participation in online games. Barriers to online connection produced ruptures that foregrounded childrens’ collaborative management of time and space. This foregrounding makes typically backgrounded practices, mode...
A novel occluded RNA recognition motif in Prp24 unwinds the U6 RNA internal stem loop

The essential splicing factor Prp24 contains four RNA Recognition Motif (RRM) domains, and functions to anneal U6 and U4 RNAs during spliceosome assembly. Here, we report the structure and characterization of the C-terminal RRM4. This domain adopts a novel non-canonical RRM fold with two additional flanking α-helices that occlude its β-sheet face, forming an occluded RRM (oRRM) domain. The flanking helices form a large electropositive surface. oRRM4 binds to and unwinds the U6 internal stem loop (U6 ISL), a stable helix that must be unwound during U4/U6 assembly. NMR data indicate that the process starts with the terminal base pairs of the helix and proceeds toward the loop. We propose a mechanistic and structural model of Prp24's annealing activity in which oRRM4 functions to destabilize the U6 ISL during U4/U6 assembly.
MOSFET's in electron-beam recrystallized PolySilicon

MOSFET's have been fabricated in polysilicon films recrystallized by scanned, cw electron-beam heating. The structure of the polysilicon is similar to the large-grain structure formed by cw laser recrystallization, and no significant differences were seen between the characteristics of transistors in material recrystallized by the two different types of heating.
Two Multiallelic Mating Compatibility Loci Separately Regulate Zygote Formation and Zygote Differentiation in the Myxomycete PHYSARUM POLYCEPHALUM.

The mating of Physarum polycephalum amoebae, the ultimate consequence of which is a "plasmodium," was recently shown to be governed by two compatibility loci, matA (or mt) and matB (Dee 1978; Youngman et al. 1979). We present evidence that matA and matB separately regulate two discrete stages of mating: in the first stage, amoebae (which are normally haploid) fuse in pairs, with a specificity determined by matB genotype, to form diploid zygotes; subsequent differentiation of the zygotes into plasmodia is regulated by matA and is unaffected by matB. Mixtures of amoebae carrying unlike matA and matB alleles formed diploids to the extent of 10 to 15% of the cells present, and the diploids differentiated into plasmodia. When only the matB alleles differed, diploid cells still formed to a comparable (5 to 10%) extent, but rather than differentiating, these diploids remained amoebae. When strains carried the same alleles of matB, formation of diploid cells was greatly reduced: in like-matB, like-matA mixtures, none of 320 cells examined was diploid; in like-matB, unlike mat-A mixtures, differentiating diploids could be detected, but at only 10-3 to 10-2 the frequency of unlike-matB, unlike-matA mixtures. The nondifferentiating diploid amoebae recovered from unlike-matB, like-matA mixtures were genetically stable through extensive growth, even though they grew more slowly than haploids (10-hr vs. 8-hr doubling period), and could be crossed with both haploids and diploids. The results of such higher ploidy and mixed ploidy crosses indicate that karyogamy does not invariably accompany zygote formation and differentiation.
The San Salvador Earthquake of October 10, 1986—Architecture and Urban Planning

Abstract Major damage from the October 10 earthquake was concentrated in and around the capital city of San Salvador. Losses exceeded $900 million, or 25% of El Salvador's 1986 gross domestic product. Poor soil conditions, ineffective land use controls, and inadequate building practices combined with the severe shaking intensity to produce widespread damage to both engineered and nonengineered structures. Residential, institutional, and commercial buildings sustained heavy damage. Nonstructural damage and damage to building contents contributed to economic and operational loss. Government officials are making a deliberate attempt to incorporate new knowledge in reconstruction planning. However, recovery and reconstruction will be a slow process due to the current state of the economy.
Electrophysics of micromechanical comb actuators

A simple approximate theory is developed for the electrostatic forces operating in a micromechanical comb actuator. The comb drive is considered both without (for simplicity) and with an underlying ground plane. The forces are partitioned into local forces (electric fields confined to the cross-sections of the individual comb fingers) and global force corrections (electric fields resulting from effective equipotential sheets representing the engaged and unengaged comb finger regions). The local forces are obtained by applying the principle of virtual work (both engaged and unengaged regions are involved when a ground plane is present beneath the comb fingers). The global forces are obtained from the force between magnetic current filaments introduced to model the electric-potential discontinuities in the effective equipotential sheets of the engaged and unengaged finger regions. Conformal mapping, in addition to a static mode decay approximation, is used to obtain simple and accurate formulas for the local charge per unit length (local forces) and, when a ground plane is present, for the effective sheet potentials (magnetic currents and global forces). The forces in the separated case (which are also global in nature) are also obtained by the principle of virtual work. The results of the paper show that the attractive local forces are independent of engagement distance and the smaller repulsive global forces are inversely proportional to engagement distance. The attractive separated forces are inversely proportional to the separation distance without the ground plane and inversely proportional to the square of the separation distance with the ground plane. >
The Life and Work of Bernard A. Galler (1928-2006)

This article describes Bernard A. Caller's involvement in early systems programming and machine languages research, his work with the ACM, and - of especial interest to the readers of this journal - his contributions to the development of the history of computing, and his role as the first editor in chief of the Annals of the History of Computing.
Disentangling the Effects of Demography and Selection in Human History

Demographic events affect all genes in a genome, whereas natural selection has only local effects. Using publicly available data from 151 loci sequenced in both European-American and African-American populations, we attempt to distinguish the effects of demography and selection. To analyze large sets of population genetic data such as this one, we introduce "Perlymorphism," a Unix-based suite of analysis tools. Our analyses show that the demographic histories of human populations can account for a large proportion of effects on the level and frequency of variation across the genome. The African-American population shows both a higher level of nucleotide diversity and more negative values of Tajima's D statistic than does a European-American population. Using coalescent simulations, we show that the significantly negative values of the D statistic in African-Americans and the positive values in European-Americans are well explained by relatively simple models of population admixture and bottleneck, respectively. Working within these nonequilibrium frameworks, we are still able to show deviations from neutral expectations at a number of loci, including ABO and TRPV6. In addition, we show that the frequency spectrum of mutations--corrected for levels of polymorphism--is correlated with recombination rate only in European-Americans. These results are consistent with repeated selective sweeps in non-African populations, in agreement with recent reports using microsatellite data.
The pseudospectral Legendre method for discretizing optimal control problems

This paper presents a computational technique for optimal control problems including state and control inequality constraints. The technique is based on spectral collocation methods used in the solution of differential equations. The system dynamics are collocated at Legendre-Gauss-Lobatto points. The derivative x/spl dot/(t) of the state x(t) is approximated by the analytic derivative of the corresponding interpolating polynomial. State and control inequality constraints are collocated at Legendre-Gauss-Lobatto nodes. The integral involved in the definition of the performance index is discretized based on the Gauss-Lobatto quadrature rule. The optimal control problem is thereby converted into a mathematical programming program. Thus existing, well-developed optimization algorithms may be used to solve the transformed problem. The method is easy to implement, capable of handling various types of constraints, and yields very accurate results. Illustrative examples are included to demonstrate the capability of the proposed method, and a comparison is made with existing methods in the literature. >
Multiresolution reproducing kernel particle methods in acoustic problems

In the analysis of complex phenomena of acoustic systems, the computational modeling requires special attention for a realistic representation of the physics. As a powerful tool, the finite element method has been widely used in the study of complex systems. In order to capture the important physical phenomena, p-finite elements and/or hp-finite elements are employed. The reproducing kernel particle methods (RKPM) are emerging as an effective alternative due to the elimination of a mesh, and the ability to analyze a specific frequency range. Additionally, a wavelet particle method based on the multiresolution analysis encountered in signal processing has been developed. The interpolation functions consist of spline functions with built-in window. A variation in the size of the window implies a geometrical refinement, and allows the filtering of the desired frequency range. Preliminary analysis of the wave equation shows the effectiveness of this approach. The frequency/wave number relationship of the continuum case can he closely simulated by using the reproducing kernel particle methods. A similar methodology is also developed for the Timoshenko beam.
IONIZING INFLUENCE OF SALTS WITH TRIVALENT AND TETRAVALENT IONS ON CRYSTALLINE EGG ALBUMIN AT THE ISOELECTRIC POINT.

1. While crystalline egg albumin is highly soluble in water at low temperature at the pH of its isoelectric point, it is coagulated by heating. It has long been known that this coagulation can be prevented by adding either acid or alkali, whereby the protein is ionized. 2. It is shown in this paper that salts with trivalent or tetravalent ions, e.g. LaCl(3) or Na(4)Fe(CN)(6), are also able to prevent the heat coagulation of albumin at the isoelectric point (i.e. pH 4.8), while salts with a divalent ion, e.g. CaCl(2), BaCl(4), Na(2)SO(4), or salts like NaCl, have no such effect. 3. This is in harmony with the fact shown in a preceding paper that salts with trivalent or tetravalent ions can cause the ionization of proteins at its isoelectric point and thus give rise to a membrane potential between micellae of isoelectric protein and surrounding aqueous solution, while the above mentioned salts with divalent and monovalent ions have apparently no such effect.
pH‐regulated activation and release of a bacteria‐associated phospholipase C during intracellular infection by Listeria monocytogenes

Listeria monocytogenes grows in the cytosol of mammalian cells and spreads from cell to cell without exiting the intracellular milieu. During cell-cell spread, bacteria become transiently entrapped in double-membrane vacuoles. Escape from these vacuoles is mediated in part by a bacterial phospholipase C (PC-PLC), whose activation requires cleavage of an N-terminal peptide. PC-PLC activation occurs in the acidified vacuolar environment. In this study, the pH-dependent mechanism of PC-PLC activation was investigated by manipulating the intracellular pH of the host. PC-PLC secreted into infected cells was immunoprecipitated, and both forms of the protein were identified by SDS-PAGE fluorography. PC-PLC activation occurred at pH 7.0 and lower, but not at pH 7.3. Total amounts of PC-PLC secreted into infected cells increased several-fold over controls within 5 min of a decrease in intracellular pH, and the active form of PC-PLC was the most abundant species detected. Bacterial release of active PC-PLC was dependent on Mpl, a bacterial metalloprotease that processes the proform (proPC-PLC), and did not require de novo protein synthesis. The amount of proPC-PLC released in response to a decrease in pH was the same in wild-type and Mpl-minus-infected cells. Immunofluorescence detection of PC-PLC in infected cells was performed. When fixed and permeabilized infected cells were treated with a bacterial cell wall hydrolase, over 97% of wild-type and Mpl-minus bacteria stained positively for PC-PLC, in contrast to less than 5% in untreated cells. These results indicate that intracellular bacteria carry pools of proPC-PLC. Upon cell-cell spread, a decrease in vacuolar pH triggers Mpl activation of proPC-PLC, resulting in bacterial release of active PC-PLC.
Yeast TFIID serves as a coactivator for Rap1p by direct protein-protein interaction.

In vivo studies have previously shown that Saccharomyces cerevisiae ribosomal protein (RP) gene expression is controlled by the transcription factor repressor activator protein 1 (Rap1p) in a TFIID-dependent fashion. Here we have tested the hypothesis that yeast TFIID serves as a coactivator for RP gene transcription by directly interacting with Rap1p. We have found that purified recombinant Rap1p specifically interacts with purified TFIID in pull-down assays, and we have mapped the domains of Rap1p and subunits of TFIID responsible. In vitro transcription of a UASRAP1 enhancer-driven reporter gene requires both Rap1p and TFIID and is independent of the Fhl1p-Ifh1p coregulator. UASRAP1 enhancer-driven transactivation in extracts depleted of both Rap1p and TFIID is efficiently rescued by addition of physiological amounts of these two purified factors but not TATA-binding protein. We conclude that Rap1p and TFIID directly interact and that this interaction contributes importantly to RP gene transcription.
Alternate Host Phenology Affects Survivorship, Growth, and Development of Western Corn Rootworm (Coleoptera: Chrysomelidae) Larvae

Abstract The commercial release of transgenic maize with resistance to rootworms incorporated with glyphosate tolerance has become a reality, and questions have arisen regarding the impact of grassy weed phenology on the biology of the western corn rootworm, Diabrotica virgifera virgifera LeConte. A study to determine the impact of host plant phenology on the survivorship (percentage larval recovery), growth (dry-weight gain), and development (change in head capsule width) of western corn rootworm larvae was conducted in a split-split-plot randomized complete block design experiment under greenhouse conditions. Six host species were evaluated under eight weekly infestations of 15 neonate western corn rootworm larvae that were sampled for larval recovery after 7, 14, and 21 d, each with five replications. Percentage larval recovery, change in head capsule width and weight gain were significantly impacted by infestation time and host species. Other than from maize, Zea mays L., larval survivorship was highe...
IN VITRO STUDIES ON THE ROLE OF THE BRAIN AND PROTHORACIC GLANDS IN THE PUPAL DIAPAUSE OF MANDUCA SEXTA

Pupal diapause in the tobacco horn worm, Manduca sexta (Johannson), is characterized by the absence of an increased ecdysteroid titre in the haemolymph during the first week of pupal life as measured by radio-immunoassay. This virtual absence of the steroid moulting hormone is thought to be responsible for the diapause state and it is apparently a consequence of the failure of the diapausing pupal prothoracic glands (PG) to synthesize ecdysone at an increased rate. In Manduca , this apparent failure of PG activation during diapause may be in response to two endo-crinological circumstances: the curtailment of PTTH release as opposed to its synthesis and transport, and the development of refractoriness of the gland to stimulation by PTTH. The former was examined by measuring PTTH activity present in brains and brain-retrocerebral complexes of diapausing and non-diapausing pupae and the latter by assessing PG biosynthetic activity in vitro in the presence and absence of PTTH.
Dense space division multiplexing long haul transport system using multi-core/multi-mode fibre

We review recent dense space division multiplexing (DSDM) transmission technologies for multi-core / multi-mode fibre and discuss issues toward future DSDM long haul transport systems.
Small Ribonucleoproteins in Ribosome Biogenesis

Small nucleolar RNPs (snoRNPs) are abundant macromolecular assemblies in the nucleolus of eukaryotic cells and are essential for the synthesis of functional ribosomes. Generally, they use their RNA components as guides to determine their site of function by means of base-pairing between guide RNA and substrate RNA. SnoRNPs have both enzymatic and non-enzymatic functions. As enzymes, they catalyze nucleotide modifications and endonucleolytic cleavages of RNA substrates. When they are not acting as enzymes, they can be scaffolds for the assembly of even larger macromolecules, for example, the SSU processome/90S preribosome, or play a role in RNA folding as chaperones. In this chapter, we review our current understanding of the function and structure of small RNPs in the nucleolus.
Shorter Perceived Outpatient MRI Wait Times Associated With Higher Patient Satisfaction

Abstract Purpose The aim of this study was to assess differences in perceived versus actual wait times among patients undergoing outpatient MRI examinations and to correlate those times with patient satisfaction. Methods Over 15 weeks, 190 patients presenting for outpatient MR in a radiology department in which "patient experience" is one of the stated strategic priorities were asked to (1) estimate their wait times for various stages in the imaging process and (2) state their satisfaction with their imaging experience. Perceived times were compared with actual electronic time stamps. Perceived and actual times were compared and correlated with standardized satisfaction scores using Kendall τ correlation. Results The mean actual wait time between patient arrival and examination start was 53.4 ± 33.8 min, whereas patients perceived a mean wait time of 27.8 ± 23.1 min, a statistically significant underestimation of 25.6 min ( P P Conclusions Patients undergoing outpatient MR examinations in an environment designed to optimize patient experience underestimated wait times at all points during their encounters. Shorter perceived and actual wait times were both correlated with higher satisfaction scores. As satisfaction surveys play a larger role in an environment of metric transparency and value-based payments, better understanding of such factors will be increasingly important.
Task parameters affecting ergonomic demands and productivity of HVAC duct installation.

BACKGROUND: Mechanical installation workers experience work-related musculoskeletal disorders (WMSDs) at high rates. OBJECTIVES: (1) Quantify the ergonomic demands during HVAC installation, (2) identify the tasks and task parameters that generated extreme ergonomic demands, and (3) propose improvements to reduce the WMSDs among mechanical workers. METHOD:The study focused on installation of rectangular ductwork components using ladders, and analyzed five operations by two mechanical contractors. Using continuous time observational assessment, the videotaped operations were analyzed along two dimensions: (1) the production tasks and durations, and (2) the ergonomic demands for four body regions (neck, arms/shoulders, back, and knees). The analysis identified tasks with low portion of productive time and high portion of extreme postures, and task parameters that generated extreme postures. RESULTS: Duct alignment was the task with the highest portion of extreme postures. The position of the ladder (angle and distance from the duct) was a task parameter that strongly influenced the extreme postures for back, neck and shoulders. Other contributing factors included the difficulty to reach the hand tools when working on the ladder, the congestion of components in the ceiling, and the space between the duct and the ceiling. CONCLUSIONS: The identified tasks and factors provide directions for improvement.
Latin@s and the Intergenerational Continuity of Spanish: The Challenges of Curricularizing Language

This paper focuses on the future of Spanish in the United States and on the tensions and challenges that surround what Fishman (1964) referred to as intergenerational continuity. It examines the teaching of language itself and the role of such instruction in the development and maintenance of Spanish/English multicompetence (Cook, 1996), that is, of the complex linguistic repertoires of Latin@s in the United States. Because language instruction generally continues to view languages as autonomous codes and systems of rules and structures, the paper draws attention to specific pedagogical questions that must be addressed by those committed to both educational access and equity for Latin@s as well as to their linguistic multicompetence in a context in which members of the new Latino/Hispanic category struggle with issues of race, class, and language, with their membership in the new panethnic category itself, and with the ways in which they are constructed by their teachers and their mainstream peers.
Evolution of host plant utilization in laboratory populations of the southern cowpea weevil, Callosobruchus maculatus Fabricius (Coleoptera : Bruchidae)

Herbivorous insects vary greatly in their utilization of host plants: almost every group includes highly polyphagous species and highly specialized species that are restricted to one or a few species of hosts. Accounting for the evolution of this diversity of feeding habits requires both ecological studies that may elucidate the selective factors that guide the evolution of diet, and genetic studies that will reveal the genetic variation on which selection acts. Genetic differences in host utilization have been documented among conspecific populations of a few species (e.g., HeslopHarrison, 1927; Painter, 1951; Dethier, 1954; Singer, 1971; Knerer and Atwood, 1973; Phillips and Barnes, 1975; Hsiao, 1978), but with few exceptions (Hatchett and Gallun, 1970; Gould, 1979; Mitter et al., 1979) little is known of genetic variation for host utilization within populations. Successful occupation of a plant requires two major features, both of which
Characterizing Atomic Composition and Dopant Distribution in Wide Band Gap Semiconductor Nanowires Using Laser-Assisted Atom Probe Tomography

Characterization of atomic composition and spatially resolved dopant distribution in wide band gap semiconducting nanowires is critical for their applications in next-generation nanoelectronic and optoelectronic devices. We have applied laser-assisted atom probe tomography to measure the spatially resolved composition of wide band gap semiconducting undoped GaN nanowires and Mg-doped GaN nanowires. Stoichiometric evaporation of individual GaN nanowires was achieved, and optimal experimental conditions to characterize the concentration and spatial distribution of the dopant in the Mg:GaN nanowire samples were established. Extremely mild operating conditions, with laser pulse energy as low as 3 pJ, are required to avoid preferential loss of nitrogen and achieve stoichiometric evaporation. The role of nanowire morphology in the selection of optimal experimental conditions is discussed in the context of thermal transport within the nanowire under a heat load imposed by the pulsing laser. The results of this w...