cssi/SciSciGPT-SciSciNet huggingface dataset:
Effects of Pulsar Rotation on Timing Measurements of the Double Pulsar System J0737–3039

We study the effect of pulsar rotation on the timing of binary pulsars, with particular emphasis on the double pulsar system J0737-3039. Special relativistic aberration due to the orbital motion of a pulsar changes both the longitude and latitude of the emission direction with respect to the pulsar spin axis. The former gives rise to a shift of the arrival time of the pulse centroid (this is the conventional "longitudinal" aberration delay), and the latter results in a distortion (contraction or dilation) of the pulse profile on the orbital timescale. In the framework of the rotating vector model of pulsar emission, the amplitude of pulse distortion depends inversely on the variation of the polarization position angle across the pulse. For a small angle between the pulsar magnetic and spin axes, as has been inferred for PSR J0737-3039A from polarimetric observations, the pulse distortion is significant (~1%) and the associated "latitudinal" aberration delay is much larger than the longitudinal one. We show that by monitoring the arrival time of separate pulse components as a function of pulsar orbital phase, the latitudinal aberration delay may be easily measured with the current timing precision. Such a measurement would constrain the spin geometry of the system. The latitudinal delay can also be detected by monitoring the system's orbital parameters on the geodetic precession timescale. Because of the near-edge-on orbital orientation of the PSR J0737-3039 system, general relativistic bending of pulsar A's radio beam near its superior conjunction also introduces spin-dependent time delays of similar orders of magnitude as the aberration delays. In addition, light bending splits the pulse profile into two variable components, corresponding to two gravitationally lensed images of the source. Detection of lensing effects is challenging, but it may be possible with existing technology.
Recent Developments in Low‐Dimensional Copper(II) Molecular Magnets

Invited for the cover of this issue is the group (current and recent students) of chemist Mark M. Turnbull and physicist Christopher P. Landee at Clark University. The image shows the types of low-dimensional lattices under study and the everyday objects that inspired them.
Corresponding Geographies: Remapping Work and Workplace in the Age of Digital Media

This essay makes three related claims about digital media creative clusters through a case study of the Hub in Glasgow, Scotland. First, online social networking platforms are an increasingly “common sense” feature that property developers include to attract media workers to purpose-built properties. Second, integrating and managing professional identities through the construction of place are considered necessary to promote that place to a larger audience. Finally, reorganizing place in this way refashions creative work as a more nebulous concept, a process that integrates formerly distinct aspects of our work and nonwork lives into the common pursuit of innovation for economic gain.
A linear programming model for optimal computer network protocol design

After providing background information on protocol modeling, we then describe a linear programming model useful in protocol design. This is followed by a description of its use and some comments on its implementation.
Muscle-like linear actuator using an ionic polymer-metal composite and its actuation characteristics

IPMC (Ionic Polymer-Metal Composite) actuators produce large bending displacements under low input voltages and are flexible enough to be implemented for biological and/or biomimetic applications. In this study, IPMC was considered for the development of a natural muscle- like linear actuator. For the purpose of design, numerical analysis was utilized to predict free strain and blocked stress of IPMC-based linear actuators, which we considered as the important parameters of muscle-like actuator. An elementary unit composed of an IPMC and the base polymer, NafionTM, was proposed for an effective linear actuator. In order to find an optimal design and evaluate the actuation characteristics of the proposed elementary unit, actuation displacement and force were numerically calculated. The optimal elementary unit produced the maximum free strain of 25% under an applied 2V input.
Analysis of cyclooxygenase-substrate interactions using stereospecifically-labeled arachidonic acids.

The two mammalian cyclooxygenase isoforms, COX-1 and COX-2, catalyze an identical reaction in the formation of prostaglandin H2 from arachidonic acid (Smith et al., 1996). The initial abstraction of the pro-S hydrogen at carbon C-13 is followed by oxygenation in the 11R position, formation of the endoperoxide and the five-membered prostaglandin ring, and, finally, a second oxygenation at C-15 to yield prostaglandin H2 (Hamberg and Samuelsson, 1967a).
Maintaining user satisfaction with performance of an online system

This paper discusses the experience of OCLC, Online Computer Library Center, Inc., with maintaining user satisfaction with performance of its online system. OCLC is an innovator in the field of automated library services. Because it is a service organization, user satisfaction with its online services of cataloging, interlibrary loan, serials control, and acquisitions is a major concern. An important component of that satisfaction is online system performance, primarily measured by response time and system availability.This paper also discusses the considerable effort that has been devoted to system support activities to address response time and availability improvement. Among the system support activities discussed are creation of an internal problem reporting and monitoring system, organizing to more clearly delineate responsibility and authority, and communication of system support activities to the user. These activities have had a positive effect on user satisfaction with OCLC's online system.
Suppression of flow-induced pressure oscillations in cavities

Experimental methods for suppressing flow-induced pressure oscillations in a shallow cavity resulting from tangential flows over the cavity are described. The effects of manipulating the shear layer over the cavity leading edge are examined. Static and oscillating fences and steady and pulsating flow injection at the leading edge are studied for their effect on cavity sound pressure levels. Both subsonic and supersonic flow conditions are considered. Of the methods tested, static fences at the leading edge were found to provide the most suppression. Suppression was dependent on the frequency mode and the flow Mach number. Nomenclature a = speed of sound D = cavity depth / = frequency k = vortex convection velocity to freestream velocity ratio L = cavity length M = Mach number m = frequency mode number P = pressure P0 = stagnation pressure Re = Reynolds number, Uxlv S = Strouhal number S * = modified Strouhal number U = freestream velocity x = distance from nozzle exit Z = cavity span, lateral dimension a = phase delay parameter y = ratio of specific heats 8 = boundary-layer thickness v = kinematic viscosity
Molecular structure of arsabenzene by gas-phase electron diffraction

Abstract Vapor-phase molecules of C 5 H 5 As were found, assuming C 2v symmetry, to have the following structure parameters and uncertainties (2.5σ): r g (C-As)= 1.850 ± 0.003 A, r g (C 2 –C 3 ) = 1.390 ± 0.032 /rA, r g (C 3 –C 4 ) = 1.401 ± 0.032 /rA, r g (C-C ave ) = 1.395 4 ± 0.002 A, ∠CAsC = 97.3 ± 1.7°, ∠AsCC = 125.1 ± 2.8°, and ∠C 3 C 3 C 4 = 124.2 ± 2.9°. Amplitudes of vibration were also determined. Auxiliary information is more restrictive than pure electron diffraction intensities as evidence that the molecule is rigorously planar. Structural characteristics of arsabenzene reinforce prior indications that the heterocyclic molecule is genuinely aromatic.
US approaches to physician payment: the deconstruction of primary care.

The purpose of this paper is to address why the three dominant alternatives to compensating physicians (fee-for-service, capitation, and salary) fall short of what is needed to support enhanced primary care in the patient-centered medical home, and the relevance of such payment reforms as pay-for-performance and episodes/bundling. The review illustrates why prevalent physician payment mechanisms in the US have failed to adequately support primary care and why innovative approaches to primary care payment play such a prominent role in the PCMH discussion. FFS payment for office visits has never effectively rewarded all the activities that comprise prototypical primary care and may contribute to the “hamster on a treadmill” problems in current medical practice. Capitation payments are associated with risk adjustment challenges and, perhaps, public perceptions of conflict with patients’ best interests. Most payers don’t employ and therefore cannot generally place physicians on salary; while in theory such salary payments might neutralize incentives, operationally, “time is money;” extra effort devoted to meeting the needs of a more complex patient will likely reduce the services available to others. Fee-for-service, the predominant physician payment scheme, has contributed to both the continuing decline in the primary care workforce and the capability to serve patients well. Yet, the conceptual alternative payment approaches, modified fee-for-service (including fee bundles), capitation, and salary, each have their own problems. Accordingly, new payment models will likely be required to support restoration of primary care to its proper role in the US health care system, and to promote and sustain the development of patient-centered medical homes.
Availability Enhancements for CAT IIIB LAAS

: Enhancements are under consideration for the Federal Aviation Administration's (FAA) Category I (CAT I) Local Area Augmentation System (LAAS) to meet the more stringent performance requirements of CAT IIIb operations. This paper analyzes the relative improvement predicted for various alternatives designed to enhance LAAS CAT IIIb availability. These enhancements include increasing the number of ranging sources, using less-conservative error models, taking credit for redundant GPS navigation sensors in the aircraft, using a second frequency to overcome the effects of ionospheric delay, or using differential carrier-phase measurements in the position solution. Availability under each scenario is computed for a vertical alert limit (VAL) ranging from 5.3 m (current requirement) to 10.0 m. Results show that unless VAL is increased beyond about 5.3 m, adequate (0.999) availability cannot be achieved merely by extending the CAT I architecture or by using any one of the above methods alone, with the exception of using dual frequency in both the ground facility and the aircraft. On the other hand, if VAL can be increased to approximately 7.5 m, some other alternatives alone and most pairwise combinations of these alternatives will provide adequate availability.
DBS: retrospective and future directions

The direct binary search (DBS) algorithm is one of a family of iterative approaches to signal design. DBS is characterized by a particular search strategy and an efficient approach to evaluating the effect of trial changes. From its origins as a method for synthesis of digital holograms, we trace the evolution of DBS to its current state as a powerful and flexible method for digital half toning and a tool for development of derivative algorithms for digital half toning. We describe the theory that underpins how DBS behaves, and discuss in some detail the use of printer models within DBS. Finally, we describe briefly the application of DBS to color half toning and its use to design halftone screens. A lookup table based algorithm, aperiodic micro screens, and halftones with an embedded watermark.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The regeneration of Pt promoted SO42−–ZrO2 catalysts

Different regeneration strategies for a Pt-SO42−–ZrO2 catalyst were investigated. Two of the regeneration methods tested on the same deactivated catalyst included sulfur addition via a SO2 step followed by a reactivation in situ step. These methods produced regenerated catalysts, which were active for the conversion of n-hexadecane. However, their high activity was not adequately sustained when compared to a fresh catalyst. Two oxidation/regeneration methods were also investigated. One oxidation method was successful in producing a catalyst that could undergo multiple regenerations with the restoration of the activity to the level of the fresh catalyst and the retention of that activity over a period of time that was comparable to, or exceeded, that of the fresh catalyst.
Synthesis of 9-alkylidene-9H-fluorenes by a novel palladium-catalyzed rearrangement

In the presence of a palladium catalyst and NaOAc, aryl iodides react with 1-aryl-1-alkynes to afford 9-alkylidene-9H-fluorenes in good yields. This process appears to involve (1) oxidative addition of the aryl iodide to Pd(0), (2) alkyne insertion, (3) rearrangement of the resulting vinylic palladium intermediate to an arylpalladium species, and (4) aryl−aryl coupling with simultaneous regeneration of the Pd(0) catalyst.
Compression and progressive transmission of astronomical images

An image compression algorithm has ben developed that is well-suited to astronomical images. The method has 3 steps: an intensity mapping to generate an image that has roughly constant noise in each pixel, an orthonormal wavelet transform, and quadtree coding of the bit-planes of the wavelet coefficients. The quadtree values may be further compressed by an standard compression technique, such as Huffman or arithmetic coding. If the 2D Haar transform is used, the calculations can be carried out using integer arithmetic, and the method can be used for both lossy and lossless compression. The Haar transform basis functions are well-suited to most astronomical images because they are highly localized. The performance of the algorithm using smoother, longer range wavelets is also shown; they can give slightly better lossy compression at the cost of an increase in artifacts around point sources, but they are not effective for lossless compression using this scheme. This technique has also been used as the basis of a progressive image transmission system that can be used for either remote observing or access to remote image archives. After less than 1% of the data have been received, the image is visually similar to the original, so it is possible to assess the quality of images very quickly. If necessary, the entire compressed data set can be sent so that the original image is recovered exactly.
Expanding the Ethical Analysis of Biobanks

Biobanks are repositories of human biological materials collected for biomedical research. There are over 300 million stored specimens in the United States, and the number grows by 20 million per year. In the post-genome world of high throughput gene sequencing and computational biology, biobanks hold the promise of facilitating large-scale research studies. New organizational and operational models of research repositories also raise complex issues of big science, big business, and big ethical concerns.
Why the Euro Will Rival the Dollar

In the aftermath of World War II, the dollar emerged as the uncontested leaderamong international currencies, a development of historic signiﬁcance. In 1899,the share of the pound in known foreign exchange holdings of ofﬁcialinstitutionshadbeenmorethantwicethetotalofthenextnearestcompetitors,the franc and the mark, and much greater than the dollar.
Characterization of Turbine Blade Friction Dampers

This paper discusses an approach for characterizing the dynamic behavior of a friction damper. To accomplish this, the deflection of the damper is measured as a function of an applied force for a range of amplitudes, normal loads, and excitation frequencies. The resulting hysteresis curves are used to generate curves of nonlinear stiffness and damping as a function of the amplitude of motion. A method of presenting this information in a dimensionless format is demonstrated. This format allows direct comparisons of the nonlinear stiffness and damping of actual dampers with that often used in analytical models to compute the dynamic response of frictionally damped turbine blades. It is shown that for the case of a damper with a spherical head significant differences exist between the actual behavior of the damper and that often assumed in simple analytical models. In addition, Mindlin s analysis of a sphere on a half space is used to estimate the damper's stiffness as well as its theoretical hysteresis curves. The hysteresis curves are then used to determine dimensionless stiffness and damping curves. The results compare favorably with those found experimentally.
Electronic and optical fine structure of GaAs nanocrystals : The role of d orbitals in a tight-binding approach

Electronic structure and optical spectra of GaAs nanocrystals for a wide range of sizes are studied by using both $s{p}^{3}{s}^{*}$ and $s{p}^{3}{s}^{*}{d}^{5}$ nearest-neighbor tight-binding models. Our results show that the inclusion of $d$ orbitals into a minimal basis set is necessary for a proper description of the lowest electron states, especially in the strong confinement regime. For dot sizes below $2.5\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, the ground electron state is primarily built of $L$-point bulk band states, giving the nanocrystals indirect-gap character. Simpler $s{p}^{3}{s}^{*}$ models yield an incorrect description of electron states made from bulk band states away from the Brillouin zone center. In contrast, $s{p}^{3}{s}^{*}{d}^{5}$ models are able to provide a consistent picture of the main optical features in agreement with experiments.
Prospects for Cosmology with Cluster Mass Profiles

We test the precision with which weak lensing data can provide characteristic cluster mass profiles within cold dark matter (CDM) scenarios. Using a parallel tree code to simulate volumes as large as 500 h-1 Mpc with good resolution, we generate samples of large clusters within a standard CDM model and an open CDM model with Ω0 = 0.3. We mock high-quality lensing data by including realistic errors, selecting cluster samples based on velocity dispersion, and fitting profiles within a realistic range in radius. We find that a sample of 10 clusters can determine logarithmic profile slopes with 1 σ errors of about 7%. Increasing the sample size to 20 brings this error down to less than 5%, but this is still insufficient to distinguish the two models. However, measures of cluster profiles obtained with weak lensing do place strong constraints for general CDM-like models of structure formation, and we discuss the optimal strategy for obtaining data samples to use for this purpose.
Effects of divided attention and operating room noise on perception of pulse oximeter pitch changes: a laboratory study.

Background: Anesthesiology requires performing visually oriented procedures while monitoring auditory information about a patient’s vital signs. A concern in operating room environments is the amount of competing information and the effects that divided attention has on patient monitoring, such as detecting auditory changes in arterial oxygen saturation via pulse oximetry. Methods: The authors measured the impact of visual attentional load and auditory background noise on the ability of anesthesia residents to monitor the pulse oximeter auditory display in a laboratory setting. Accuracies and response times were recorded reflecting anesthesiologists’ abilities to detect changes in oxygen saturation across three levels of visual attention in quiet and with noise. Results: Results show that visual attentional load substantially affects the ability to detect changes in oxygen saturation concentrations conveyed by auditory cues signaling 99 and 98% saturation. These effects are compounded by auditory noise, up to a 17% decline in performance. These deficits are seen in the ability to accurately detect a change in oxygen saturation and in speed of response. Conclusions: Most anesthesia accidents are initiated by small errors that cascade into serious events. Lack of monitor vigilance and inattention are two of the more commonly cited factors. Reducing such errors is thus a priority for improving patient safety. Specifically, efforts to reduce distractors and decrease background noise should be considered during induction and emergence, periods of especially high risk, when anesthesiologists has to attend to many tasks and are thus susceptible to error.
THE TOXICOLOGICAL CONSTITUTION OF AMANITA PHALLOIDES

From the experiments detailed in this paper it may be concluded that Amanita phalloides contains besides phallin, or the haemolytic principle of Kobert, another body of toxic nature. Phallin is thermolabile, and is destroyed by the action of pepsin and pancreatin. The other toxic body is thermostable and is resistant to pepsin and pancreatin. The two substances, moreover, possess different toxophoric and haptophoric groups, since an antiserum produced by the immunization of animals to the thermostable body has no neutralizing effects upon phallin. The thermolable body, phallin, produces the subcutaneous oedema and haemoglobinuria, and, in virtue of its blood-laking properties, the pigmentation of the spleen. The thermostable body produces haemorrhage and necrosis, and the fatty degeneration of the parenchymatous organs. The two bodies exist side by side in watery extracts of the fungus, but they cannot be considered as two constituents of a single poison exerting a variety of effects. To the haemolysin the name phallin has already been given by its discoverer, Kobert. For the thermostable substance described now for the first time, the name Amanito-toxin is proposed provisionally.
Bulge and Halo Kinematics Across the Hubble Sequence

The correlation between the maximum rotational velocity of the disk (vm) and the central stellar velocity dispersion of the bulge (σ0) offers insights into the relationship between the halo and the bulge. We have assembled integrated H I line widths and central stellar velocity dispersions to study the vm-σ0 relation for 792 galaxies spanning a broad range of Hubble types. Contrary to earlier studies based on much smaller samples, we find that the vm-σ0 relation exhibits significant intrinsic scatter and that its zero point varies systematically with galaxy morphology, bulge-to-disk ratio, and light concentration, as expected from basic dynamical considerations. Nucleated but bulgeless late-type spiral galaxies depart significantly from the vm-σ0 relation. While these results render questionable any attempt to supplant the bulge with the halo as the fundamental determinant of the central black hole mass in galaxies, the observed distribution of vm/σ0, which depends on both the density profile and kinematic structure of the galaxy, offers a useful constraint on galaxy formation models. With the aid of a near-infrared Tully-Fisher relation, we identify a population of otherwise normal, luminous galaxies that have exceptionally low values of vm/σ0. We argue that a significant fraction of the H I gas in these kinematically anomalous objects is dynamically unrelaxed, having been acquired externally either through capture from tidal interactions or through cold accretion from the intergalactic medium.
D-Phe-Pro-p-Amidinobenzylamine: A potent and highly selective thrombin inhibitor

Abstract The design, synthesis, and enzyme inhibitory profile of D-Phe-Pro-p-Amidinobenzylamine are presented. This compound has inhibitory activity equivalent to D-Phe-Pro-Arg-H, two orders of magnitude more potent than D-Phe-Pro-Agmatine. The results indicate that binding energy provided by the covalent bond of a transition-state analog can be replaced with noncovalent interactions.
Chemical vapor deposition of spectrally selective surfaces for high temperature photothermal conversion

Abstract Chemical vapor deposition was adapted to the fabrication of multilayer thin film systems of the spectral selectivity required for photothermal solar energy conversion. The systems operate on the principle of an absorber-reflector tandem, the absorption of the solar photons being accomplished by a layer of polycrystalline or amorphous silicon and the thermal emittance being reduced by a silver or molybdenum reflector. The surfaces were tested for several thousand hours at 500°C without degradation of their optical performance.
Vanadyl Triflate as an Efficient and Recyclable Catalyst for the Synthesis of α‐Aminonitriles

Abstract Vanadyl triflate to catalyzed Strecker‐type reactions were successfully carried out by simply mixing aldehydes, amines, and trimethylsilyl cyanide at room temperature to afford α‐aminonitriles in good yields.
A nonparametric analysis of the black/white wage gap

This article estimates a nonparametric model of earnings to examine the black/white wage gap. This article extends the Oaxaca decomposition and adjusted wage ratios to a nonlinear form, to allow the use of this nonparametric approach. It finds that the results obtained nonparametrically are very similar to those obtained with variants of the (misspecified) Mincer model, suggesting that the parametric models may be appropriate in situations where the nonparametric estimator could not be applied.
Screening a hydroxystilbene library for selective inhibition of the B cell antigen receptor kinase cascade

Abstract Protein tyrosine phosphorylation is a key post-translational modification used by eukaryotic cells in receptor mediated signal transduction. Selective inhibition of cellular phosphorylation would aid efforts to elucidate the individual events in a signaling pathway. A combinatorial library of putative kinase inhibitors has been screened using an anti-phosphotyrosine blotting assay that can detect inhibition of individual phosphorylation events in whole cells. One member of the library, 3-hydroxy-4-methoxy-4′-nitro-trans-stilbene (2B), has been found to selectively disrupt the phosphorylation of several proteins in the B cell receptor mediated cascade while not affecting other cellular phosphorylation events. The kinase specificity of stilbene 2B is compared to known natural and synthetic kinase inhibitors.
An Optical Precursor to the Recent X-Ray Outburst of the Black Hole Binary GRO J1655–40

The All-Sky Monitor on the Rossi X-Ray Timing Explorer detected an X-ray (2-12 keV) outburst from the black hole binary GRO J1655-40 beginning near 1996 April 25. Optical photometry obtained on 1996 April 20-24 shows a steady brightening of the source in B, V, R, and I beginning about 6 days before the start of the X-ray outburst. The onset of the optical brightening was earliest in I and latest in B. However, the rate of the optical brightening was fastest in B and slowest in I. The order of the increases in the different optical filters suggests that the event was an "outside-in" disturbance of the accretion disk. The substantial delay between the optical rise and the rise of the X-rays may provide indirect support for the advection-dominated accretion flow model of the inner regions of the accretion disk.
Ion-beam mixing in silicon and germanium at low temperatures

Ion-beam mixing of thin marker layers in amorphous silicon and germanium was studied using irradiations with Xe ions at temperatures of 34k and 77k. The marker species, ion energies and doses were: in silicon, markers of Ge and Pt irradiated with 200-keV Xe up to 2.7x10/sup 16/ ions cm/sup -2/; and in germanium, markers of Al and Si bombarded with 295-keV Xe up to 1.63x10/sup 16/ ions cm/sup -2/. In silicon, Pt markers were found to broaden at about the same rate at 34k and 77k; and the rate of broadening was similar to that found by other workers when expressed as an efficiency of mixing, i.e., when dependence on ion dose and deposited energy was factored out. However, a Ge marker irradiated at 34k did not broaden from its original thickness. In germanium, markers of both Al and Si were mixed by irradiation at 34k, but at 77k only the Al marker broadened; the Si marker did not. The broadening of the markers is ascribed to ballistic mixing, while the cases where no broadening occurred are explicable if diffusion by a defect mechanism transported displaced marker atoms back to traps near their original sites.
Quiver varieties and Lusztig's algebra

Abstract We study preprojective algebras of graphs and their relationship to module categories over representations of quantum SL ( 2 ) . As an application, ADE quiver varieties of Nakajima are shown to be subvarieties of the variety of representations of a certain associative algebra introduced by Lusztig.
Copper(I) and Copper(II) Coordination Structure under Hydrothermal Conditions at 325 °C: An X-ray Absorption Fine Structure and Molecular Dynamics Study

X-ray absorption fine structure (XAFS) spectroscopy was used to measure the coordination structure about Cu2+, Cu1+, and Br- in water at temperatures up to 325 °C. The hexaaqua Cu2+ species maintains its distorted octahedral structure up to 325 °C, whereas at higher temperatures, dehydration reactions occur producing CuO. Under reducing conditions, the dibromo Cu1+ species, [CuBr2]-, is predominant at 200 °C and above for systems having excess Br-. Even for a very high salt concentration of 2.0 m NaBr, only the dibromo Cu1+ species, [CuBr2]-, is observed with no evidence of higher Br- coordination. For this dibromo-species there are no tightly bound hydration waters in the first shell. In the absence of excess Br-, a monoaqua monobromo Cu1+ species, [Cu(H2O)Br] is observed. For certain systems, both Cu and Br XAFS were acquired, and a global model was used to fit the two independent sets of XAFS data. Thus, the results represent a complete picture of the coordination structure about Cu1+ including the coo...
Computer Room Fire Protection

Fire protection has several components: prevention, containment, detection, and suppression. While building codes and inspectors generally do not require special construction techniques or fire protection systems for computer rooms, economic and service factors may dictate that special protection be given such facilities. This article discusses emergency planning, the various types of fire detection and suppression systems, and future options, with particular attention given to halon and possiblehalon‐replacements.
Applications of mass spectrometry for quantitation of DNA adducts

DNA adducts are formed when electrophilic molecules or free radicals attack DNA. 32P-postlabeling has been the most commonly used assay for quantitation of DNA adducts due mainly to its excellent sensitivity that allows quantitation at concentrations as low as approximately 1 adduct per 10(9) normal bases. Such methods, however, do not have the specificity desired for accurate and reliable quantitation, and are prone to produce false positives and artifacts. In the last decade, mass spectrometry in combination with liquid and gas chromatography has presented itself as a good alternative to these techniques since it can satisfy the need for specificity and reliability through the use of stable isotope-labeled internal standards and highly specific detection modes such as selected reaction monitoring and high-resolution mass spectrometry. In this article, the contribution of mass spectrometry to the quantitation of DNA adducts is reviewed with special emphasis on unique applications of mass spectrometry in the area of DNA adduct quantitation and recent applications with improvements in sensitivity.
A discussion of fire suppression induced equipment damage and systems impact through an examination of spurious fire suppression actuation incidents

Abstract This paper will discuss current work associated with the investigation of equipment damage induced by the application of fire suppressants. This discussion will be presented through an examination of several nuclear power plant incidents in which the spurious actuation of one or more fire suppression systems has occurred. The effects of these actuations on plant equipment, systems, and operation will be described. Also presented are the results of scoping calculations of the risk significance of spurious suppression system actuation. Finally, the paper will provide a description of efforts recommended to further investigate the impact of such incidents on plant operations and plant risk.
Closed and Open Conformal Field Theories and Their Anomalies

We describe a formalism allowing a completely mathematical rigorous approach to closed and open conformal field theories with general anomaly. We also propose a way of formalizing modular functors with positive and negative parts, and outline some connections with other topics, in particular elliptic cohomology.
Debugging in a time-sharing environment

In the past 10 years, rapid advances have been made in computer engineering and programming. Among the significant achievements have been the development of more powerful computers, multiprocessing systems, high-level language compilers, multiprogramming operating systems, and time-sharing systems.
Nonlinear Charge Control for a Collinear Fixed-Shape Three-Craft Equilibrium

The collinear equilibrium three-craft-formation charge feedback control problem is investigated. Given a charged-equilibrium collinear configuration of spacecraft flying in deep space, a nonlinear charge feedback control algorithm is developed to stabilize the formation to the desired shape and size. The Coulomb forces are assumed to be acting along the line-of-sight directions between the bodies and thus do not provide general vehicle position controllability. A study of the charged collinear three-craft formation shows that there exists an infinite number of equilibrium charge solutions for any collinear configuration. Given a real value of one spacecraft charge, the required equilibrium charges of the remaining two vehicles are solved analytically. A Lyapunov-based nonlinear control algorithm is developed to stabilize the configuration to the equilibrium state using only the spacecraft charges as the control states. Real charge solutions are ensured by using the one-dimensional solution null-space. Numerical simulations illustrate the new charge feedback control performance. In contrast to earlier efforts, collinear configurations are stabilized even in the presence of very large initial position errors.
New cytotoxic annonaceous acetogenins: Bullatanocin and cis- and trans-Bullatanocinone, from Annona bullata (Annonaceae)

Abstract Further bioactivity-directed fractionation of the ethanol extract of the bark of Annona bullata Rich. (Annonaceae) has led to the isolation of the new nonadjacent bis-tetrahydrofuran acetogenins, bullatanocin ( 1 ), cis- bullatanocinone ( 2 ) and trans-bullatanocinone ( 3 ). A known adjacent bis-tetrahydrofuran acetogenin, desacetyluvaricin ( 4 ), which is new to this species, was also isolated. Brine shrimp lethality test (BST) data and cytotoxicities against human solid tumor cell lines of 1–4 were compared with those of the diastereoisomers, bullatalicin ( 5 ), cis- and trans-bullatalicinone ( 6 and 7 ) and 4-deoxyasimicin ( 8 ). 1 shows cytotoxic potencies 10,000 times those of adriamycin in the lung and colon cancer cell lines.
Denoising deterministic time series

This paper is concerned with the problem of recovering a finite, deterministic time series from observations that are corrupted by additive, independent noise. A distinctive feature of this problem is that the available data exhibit long-range dependence and, as a consequence, existing statistical theory and methods are not readily applicable. This paper gives an analysis of the denoising problem that extends recent work of Lalley, but begins from first principles. Both positive and negative results are established. The positive results show that denoising is possible under somewhat restrictive conditions on the additive noise. The negative results show that, under more general conditions on the noise, no procedure can recover the underlying deterministic series.
Tandem Henry/oxa-Michael route to the 1,3-disubstituted-1,3-dihydrobenzo[c]furan system☆

Abstract The reaction of ortho -formyl cinnamates and ortho -formyl-α-benzalketones with suitably substituted alkylnitro compounds in the presence of 1,1,3,3-tetramethylguanidine results in the formation of 1,3-disubstituted dihydroisobenzofurans. The reaction mechanism entails a base-mediated nitronate addition to the aryl formyl group followed by intramolecular alcoholate addition to the unsaturated component that then affords the isobenzofuran system.
Why are vertebrate nervous systems crossed

Contralateral central nervous control may be an evolutionary consequence of dependence on the image-forming eye, especially in large organisms. As a result of the topological transformation of the visual stimulus in the pupillary eye, the external environmental hemispace impinges directly upon the contralateral internal organismal hemispace. Selective pressure leads to the development of central connections capable of the most rapid and precise functional association of the internal milieu with the organism's environment. The consequence is contralateral central sensorimotor control. Previous hypotheses are discussed, including those based on bilaterality, binocularity, the optic chiasm and avoidance behaviors.
Recirculating mixed convection flows in rectangular cavities

A numerical investigation is carried out to determine the flow and thermal structures of mixed convective flow in a rectangular cavity. The effect of aiding and opposing buoyancy on the flow in a vertical downward laminar jet is studied for Re < 200, -1.0 < 'Ri < 0.5, and 0.5 < A < 5.0. Such flow situations occur in enclosure fires, energy storage, and ventilation systems. Results of the velocity profile, temperature distribution, local friction factor, and heat-transfer coefficient are presented for both hot and cold jets. The flow configuration is found to be strongly affected by the positive and negative buoyancy and also by the aspect ratio of the cavity.
A Model for Dynamic Evolution of Emerging Magnetic Fields in the Sun

In this paper we study the dynamic evolution of emerging magnetic fields in the solar atmosphere by deriving a model based on a three-dimensional MHD simulation. The simulation shows that magnetic field lines initially forming a twisted flux tube below the solar surface emerge into the atmosphere by magnetic buoyancy. Outer field lines of the flux tube are almost free to expand in a wide fan shape without strong confinement by surrounding field lines. On the other hand, inner field lines are subject to strong confinement by adjacent twisted field lines that prevent the lateral expansion of inner field lines. By examining the result of the simulation, we derive a model of emerging field lines to demonstrate that the height of an emerging field line increases at the average rate of (g0κ)1/2H/2, where g0, κ, and H are the gravitational acceleration, curvature of the emerging field line, and a scale height of magnetic field strength. Applying this model to the outer and inner field lines, we show that inner field lines are less dynamical than outer field lines and inner field lines are likely to form quasi-static structure in the corona such as prominences and sigmoids. We also discuss that the shape of inner field lines is reflected in the chirality of a modeled sigmoid.
The depth of chemical time and the power of enzymes as catalysts.

The fastest known reactions include reactions catalyzed by enzymes, but the rate enhancements that enzymes produce had not been fully appreciated until recently. In the absence of enzymes, these same reactions are among the slowest that have ever been measured, some with half-times approaching the age of the Earth. This difference provides a measure of the proficiencies of enzymes as catalysts and their relative susceptibilities to inhibition by transition-state analogue inhibitors. Thermodynamic comparisons between spontaneous and enzyme-catalyzed reactions, coupled with structural information, suggest that in addition to electrostatic and H-bonding interactions, the liberation of water molecules from an enzyme's active site into bulk solvent sometimes plays a prominent role in determining the relative binding affinities of the altered substrate in the ground state and transition state. These comparisons also indicate a high level of synergism in the action of binding determinants of both the substrate a...
The Effect of Seal Width on Regenerator Effectiveness

The effect of axial conduction on regenerator effectiveness has been studied in the past under the assumption of zero seal width. The effect of axial conduction coupled with finite seal width is presented in this paper. A method for calculating effectiveness assuming axial conduction and finite seal width is presented. Results of sample calculations are presented to give the designer a feel for the dependence of seal width effects on system-parameter values. It is shown that for typical regenerator designs, reductions in effectiveness due to axial conduction coupled with finite seal width can be twice as great as those due to axial conduction under the assumption of zero seal width. Also, it is shown that the required regenerator size to achieve a given effectiveness can increase dramatically when finite seal width is considered in design procedures. It is concluded that consideration of axial conduction should include finite seal width.
Currency Substitution in Egypt and the Yemen Arab Republic: A Comparative Quantitative Analysis

An empirical analysis of the determinants of currency substitution in Egypt and the Yemen Arab Republic is provided for the period 1980-86. During this period, residents exhibited a marked preference to substitute foreign money balances for domestic balances, as indicated by their holdings of foreign currency deposits. This preference reflects changes in the expected relative returns to, and liquidity of, holdings of foreign balances. Such changes, in turn, are shown to result from intensified financial and economic imbalances, increased political uncertainties, and changes in institutional factors that affect domestic channels for acquiring and using foreign exchange resources.
A determination of the local density of white dwarf stars

The most recent version of the Catalog of Spectroscopically Identified White Dwarfs lists 2249 white dwarf stars. Among these stars are 109 white dwarfs that have either reliable trigonometric parallaxes or color-based distance moduli that place them at a distance within 20 pc of the Sun. Most of these nearby white dwarfs are isolated stars, but 28 (25% of the sample) are in binary systems, including such well-known systems as Sirius A/B and Procyon A/B. There are also three double degenerate systems in this sample of the local white dwarf population. The sample of local white dwarfs is largely complete out to 13 pc, and the local density of white dwarf stars is found to be 5.0 ? 0.7 ? 10-3 pc-3, with a corresponding mass density of 3.4 ? 0.5 ? 10-3 M? pc-3.
Stock returns in thinly traded markets

We examine the share price behavior of thinly traded NASDAQ National Market System stocks during periods when financial markets are open but the individual stocks do not trade. The absence of trade allows us to isolate the effect of nontrading from that of market closure. We find that nontrading stocks have negative mean returns and lower variances regardless of whether markets are open or closed. Two-day returns that include one nontrading day have a mean daily return of -0.226% compared to +0.164% for two-day returns over consecutive trading days. Two-day returns that include one nontrading day have only 3.8% higher variance than one-day returns. We conclude that the relation between transaction arrival, mean returns, and volatility depends on whether a stock is trading and not simply on whether the market is open.
The macrocyclization reaction of terminal dibromoalkanes with sulfide on alumina. The use of a solid support as an alternative to the high dilution technique.

Abstract The reaction of a series of terminal dibromoalkanes with S −2 on Al 2 O 3 has been examined. The use of a solid support for the macrocyclization represents a viable alternate procedure to the more traditional high dilution technique in solution. The cyclizations also occur with thioacetamide on unactivated alumina.
Ruthenium-catalyzed decarboxylative insertion of electrophiles.

A ruthenium complex, Cp*Ru(bipyridyl)Cl, has been developed as a catalyst for the first regioselective tandem Michael addition−allylic alkylation of activated Michael acceptors. The net transformation is the decarboxylative insertion of Michael acceptors into allyl β-ketoesters.
Syntheses, Structures, and Ion-Exchange Properties of the Three-Dimensional Framework Uranyl Gallium Phosphates, Cs4[(UO2)2(GaOH)2(PO4)4]·H2O and Cs[UO2Ga(PO4)2]

The reaction of UO(2)(NO(3))(2).6H(2)O with Cs(2)CO(3) or CsCl, H(3)PO(4), and Ga(2)O(3) under mild hydrothermal conditions results in the formation of Cs(4)[(UO(2))(2)(GaOH)(2)(PO(4))(4)].H(2)O (UGaP-1) or Cs[UO(2)Ga(PO(4))(2)] (UGaP-2). The structure of UGaP-1 was solved from a twinned crystal revealing a three-dimensional framework structure consisting of one-dimensional (1)(infinity)[Ga(OH)(PO(4))(2)](4-) chains composed of corner-sharing GaO(6) octahedra and bridging PO(4) tetrahedra that extend along the c axis. The phosphate anions bind the UO(2)(2+) cations to form UO(7) pentagonal bipyramids. The UO(7) moieties edge-share to create dimers that link the gallium phosphate substructure into a three-dimensional (3)(infinity)[(UO(2))(2)(GaOH)(2)(PO(4))(4)](4-) anionic lattice that has intersecting channels running down the b and c axes. Cs(+) cations and water molecules occupy these channels. The structure of UGaP-2 is also three-dimensional and contains one-dimensional (1)(infinity)[Ga(PO(4))(2)](3-) gallium phosphate chains that extend down the a axis. These chains are formed from fused eight-membered rings of corner-sharing GaO(4) and PO(4) tetrahedra. The chains are in turn linked together into a three-dimensional (3)(infinity)[UO(2)Ga(PO(4))(2)](1-) framework by edge-sharing UO(7) dimers as occurs in UGaP-1. There are channels that run down the a and b axes through the framework. These channels contain the Cs(+) cations. Ion-exchange studies indicate that the Cs(+) cations in UGaP-1 and UGaP-2 can be exchanged for Ca(2+) and Ba(2+). Crystallographic data: UGaP-1, monoclinic, space group P2(1)/c, a = 18.872(1), b = 9.5105(7), c = 14.007(1) A, beta = 109.65(3)(o) , Z = 4 (T = 295 K); UGaP-2, triclinic, space group P, a = 7.7765(6), b = 8.5043(7), c = 8.9115(7) A, alpha = 66.642(1)(o), beta = 70.563(1)(o), gamma = 84.003(2)(o), Z = 2 (T = 193 K).
Top seesaw with a custodial symmetry, and the 126 GeV Higgs

The composite Higgs models based on the top seesaw mechanism commonly possess an enhanced approximate chiral symmetry, which is spontaneously broken to produce the Higgs field as the pseudo-Nambu-Goldstone bosons. The minimal model with only one extra vector-like singlet quark that mixes with the top quark can naturally give rise to a 126 GeV Higgs boson. However, without having a custodial symmetry it suffers from the weak-isospin violation constraint, which pushes the chiral symmetry breaking scale above a few TeV, causing a substantial fine-tuning for the weak scale. We consider an extension to the minimal model to incorporate the custodial symmetry by adding a vector-like electroweak doublet of quarks with hypercharge +7/6. Such a setup also protects the $$ Zb\overline{b} $$ coupling which is another challenge for many composite Higgs models. With this addition, the chiral symmetry breaking scale can be lowered to around 1 TeV, making the theory much less fine-tuned. The Higgs is a pseudo-Nambu-Goldstone boson of the broken O(5) symmetry. For the Higgs mass to be 126 GeV, the hypercharge +7/6 quarks should be around or below the chiral symmetry breaking scale, and are likely to be the lightest new states. The 14 TeV LHC will significantly extend the search reach of these quarks. To probe the rest of the spectrum, on the other hand, would require a higher-energy future collider.