cssi/SciSciGPT-SciSciNet huggingface dataset:
Fe Superoxide Dismutase

Iron-containing superoxide dismutases (FeSOD) are generally dimers of identical 21-kDa monomers, each of which contains a single active site. Each active site binds one Fe ion with roughly trigonal bipyramidal geometry, employing two His and an Asp− residue as equatorial ligands, and one more His and a coordinated solvent as axial ligands. In the course of the catalytic cycle, the Fe alternates between the +3 and +2 states, and the coordinated solvent is believed to alternate between OH− and H2O, in concert. Activity is inhibited by coordination of F−, N3−, or OH− to the oxidized state. Decreased activity at high pH reflects the latter in addition to ionization of the conserved Tyr34 in the reduced state of the enzyme at pH 8.5. Despite strong structural homologies with the manganese containing superoxide dismutases (MnSODs), many FeSODs are inactive when reconstituted with Mn, and in the case of Escherichia coli SODs this appears to reflect, at least in part, very large differences in the reduction potentials produced by the two different SOD proteins, either Fe or Mn. Subtle changes in strengths of key active site H-bonds could differently tune the pKs of the coordinated solvent molecule, whose participation in proton-coupled electron transfer would in turn cause these differences to contribute to different reduction potentials, in the two proteins. Thus, SOD suggests that H-bond mediated tuning of the protonation state and pKs of redox-coupled coordinated solvents may serve as a means of tuning the Em in other cases as well. 3D Structure Keywords: iron; non-heme proteins; mononuclear iron proteins; enzyme; E.C. 1.15.1.1; mononuclear non-heme; non-sulfur Fe enzyme
The synthesis of messenger RNA without protein synthesis: I. Studies with thymineless strains of Escherichia coli

Escherichia coli , deficient in the ability to synthesize thymine, uracil and an amino acid, synthesize a small fraction of their normal RNA from uracil in the absence of thymine and the amino acid. The synthesis of even this fraction of RNA is inhibited by concomitant DNA synthesis. Most (75%) of the RNA made appears on the ribosomes and can be degraded on these structures in the presence of inorganic phosphate. When synthesized in the presence of an inducer of β -galactosidase, the RNA appears to permit the rapid synthesis of a small amount of this enzyme in the apparent absence of the inducer. These observations are consistent with the hypothesis that the RNA made in the absence of an essential amino acid and of protein synthesis is largely messenger RNA.
Pathogenetic Mechanisms of Stress

For a rational use of stress tests and an appropriate interpretation of their results, it may be useful to adopt a pathogenetic classification, taking into account the diagnostic end point of the test. Tests inducing vasospasm (ergonovine infusion and hyperventilation) explore the functional component. Tests trying to unmask coronary stenosis (exercise, dipyridamole, adenosine, dobutamine, pacing) mostly explore the ceiling of coronary reserve as defined by organic factors (Fig. 1). Some of these stressors (such as exercise) may also induce variations in coronary tone which can be superimposed on to the organic factors, thus blurring the correlation between coronary anatomy and test positivity.
Can Galactic GMCs be Identified from l-v Diagrams?

Identifying the spiral nature of the distribution of gas in the Galaxy has been a subject of much research in the past thirty years. The position of the sun in the disk of the Galaxy presents us with a problem of perspective: how does one identify the cloud system from within the system? Longitude-velocity (l-v) diagrams have been used to try to determine the distribution of interstellar gas, but problems inherent in the methods have been pointed out previously (Burton 1971). Recent Galactic CO surveys have been used in attempts to map the distribution of molecular cloud complexes in the disk of the Galaxy (Dame, et al. 1986). Here, we use numerical simulations of the molecular cloud system in a spiral galaxy to consider the following question: to what extent can concentrations of emission in the l-v diagram (LVCs) be considered complexes of gas in the disk of the Galaxy (GMCs)?
Features of Representations in General Chemistry Textbooks: A Peek through the Lens of the Cognitive Load Theory.

The goals of this study were (1) determine the prevalence of various features of representations in five general chemistry textbooks used in the United States, and (2) use cognitive load theory to draw implications of the various features of analyzed representations. We adapted the Graphical Analysis Protocol (GAP) (Slough et al., 2010) to look at the type of representations used, the function of each representation, the physical integration of representations with associated text, the presence and nature of captions and labels, the indexing of representations, and the number of representations requiring conceptual integration on a given page. Results indicate that on average, in all five textbooks each page had at least four representations. Most representations served a ‘representational’ function, but a number functioned as decorative representations. Most representations were directly integrated with text, but some of the remaining representations were separated by a whole page from associated text. While many pages had an average of two representations that required conceptual integration with text or other representations, some pages had as many as six representations requiring integration. While using textbooks, learners can experience intrinsic, germane or extraneous cognitive load (Sweller, 1994). Our findings indicate that there are various features of representations that could help reduce intrinsic or extraneous cognitive load. However, we also found prevalent features of representations that imply high intrinsic cognitive load or are likely to lead to extraneous cognitive load. Implications for textbook authors and editors, textbook selection, instruction, and science teacher preparation are discussed.
Pathogenesis of African swine fever virus in Ornithodoros ticks.

African swine fever virus (ASFV) is the only known DNA arbovirus and the sole member of the family Asfarviridae. It causes a lethal, hemorrhagic disease in domestic pigs. ASFV is enzootic in sub-Saharan Africa and is maintained in a sylvatic cycle by infecting both wild members of the Suidae (e.g. warthogs) and the argasid tick Ornithodoros porcinus porcinus. The pathogenesis of ASFV in O. porcinus porcinus ticks is characterized by a low infectious dose, lifelong infection, efficient transmission to both pigs and ticks, and low mortality until after the first oviposition. ASFV pathogenesis in warthogs is characterized by an inapparent infection with transient, low viremic titers. Thus O. porcinus porcinus ticks probably constitute the most important natural vector of ASFV, although both the mammalian and tick hosts are probably required for the maintenance of ASFV in the sylvatic cycle. The mechanism of ASFV transmission from the sylvatic cycle to domestic pigs is probably through infected ticks feeding on pigs. In addition to O. porcinus porcinus, a number of North American, Central American and Caribbean species of Ornithodoros have been shown to be potential vectors of ASFV.
Ground fault monitoring in Alcator C-MOD

The Alcator C-MOD tokamak has a complex AC power distribution system to power diagnostic equipment, magnet power, vacuum, heating, and cryogenic control. During a 9 Tesla pulse, the existence of ground loops between these systems can cause damage or compromise the performance of the associated equipment. The real-time detection of these ground loops in the grounding system is crucial to the productive operation of the tokamak. The ground fault monitor is capable of detecting ground loops with an impedance as high as 10 K/spl Omega/. This monitoring system utilizes current transformers and a multiplexed driver/sensor architecture to monitor each of the 20 ground lines that are connected to a star point ground in the C-MOD cell. Continuous monitoring is accomplished without breaking ground wire connections. The star ground cable to earth ground is monitored to detect ground leakage paths that circumvent the star ground point. A synchronous demodulator circuit is utilized to detect the driver signal in a noisy environment and in the presence of 60 Hz leakage current. The detector output is linear for fault impedance values in the range of 100 K/spl Omega/ to 100 /spl Omega/. The detection of 60 Hz leakage current is possible with the use of an alternate measurement mode. The monitor runs continuously to detect faults as they occur. Outputs are monitored in the control room via a fiber optic interface. Control room functionality includes data logging of fault conditions, overrides, and alarms. A manual operating mode and instrument rack display panel can be utilized by the operator for tracking down ground faults. A diagnostic circuit is available to perform a "self-test" function, which verifies proper monitor operation and locates defective circuitry down to the component level.
Channel stability and sediment source assessment in streams draining a Piedmont watershed in Georgia, USA

Streams can be classified as stable or unstable, depending on the stage of channel evolution. Many streams of the southern Piedmont in United States have high sediment loads and are listed as impaired under the total maximum daily load (TMDL) program and may be unstable. It is not clear as to what the target (reference) load or remediation measures should be for unstable streams. The objective of this study was to determine the relative channel stability for a typical southern Piedmont stream using rapid geomorphic assessments (RGAs) and sediment yield analysis. The results were supported through a sediment fingerprinting analysis. RGAs were performed along 52 reaches on the North Fork Broad River (NFBR) main stem and two tributaries. Annual sediment yields were calculated and compared with yields in the southern Piedmont for stable streams that are resilient to degradation or aggradation and unstable streams that are susceptible to such disturbances. Majority of the NFBR main stem was found to be unstable with signs of geomorphic instability in the form of degradation and aggradation. The estimated average annual sediment yield was 0·78 T ha−1 year−1. By comparison, the median annual yield is 0·20 T ha−1 year−1 for stable streams and 0·48 T ha−1 year−1 for unstable streams in the Piedmont ecoregion with comparable drainage basin size. We conclude that the NFBR is in an unstable stage of channel evolution. Sediment fingerprinting proved that majority of the stream-suspended sediment emanated from eroding stream channels. The methods outlined in this study have implications for the reference condition and remediation efforts related to stream turbidity and stream channel restoration. Copyright © 2010 John Wiley & Sons, Ltd.
Surgical Treatment of Aneurysms of the Intrathoracic Segment of the Subclavian Artery

From June 1969 to May 1986, 16 patients underwent 17 operations to treat 18 aneurysms of the intrathoracic segment of the subclavian artery. Surgical treatment in 12 cases involved Dacron tube graft replacement; in the remainder, patch graft angioplasty or exclusion with and without extra-anatomic revascularization were utilized. Twelve patients required simultaneous graft replacement of aortic aneurysms. Five procedures were performed through a median sternotomy and 12 through a left posterior lateral thoracotomy. Deep hypothermia and circulatory arrest was used on three occasions. All but one patient were early survivors, and there were no related cerebrovascular accidents. There were five late deaths unrelated to operative treatment. Surgical treatment of aneurysms of the intrathoracic segment of the subclavian artery is both well tolerated and durable.
A 3-D anisotropic diffusion filter for speckle reduction in 3-D ultrasound images

In this paper, we study speckle reduction technology for 3-D ultrasound images and a 3-D anisotropic diffusion (AD) filter is developed. The 3-D anisotropic diffusion filter works directly in the 3-D image domain and can overcome the limitations of the 2-D anisotropic diffusion filter and the traditional 3-D anisotropic diffusion filter. The proposed algorithm uses normalized gradient to replace gradient in the computation of the diffusion coefficients, which can reduce the speckle effectively while preserving the edges. Experiments have been performed on real 3-D ultrasound images and the experimental results show the effectiveness of the proposed 3D anisotropic diffusion filter.
A peptide agonist acts by occupation of a monomeric G protein-coupled receptor: dual sites of covalent attachment to domains near TM1 and TM7 of the same molecule make biologically significant domain-swapped dimerization unlikely.

Membrane receptor dimerization is a well-established event for initiation of signaling at growth factor receptors and has been postulated to exist for G protein-coupled receptors, based on correction of nonfunctional truncated, mutant, or chimeric constructs by coexpression of appropriate normal complementary receptor domains. In this work, we have directly explored the molecular composition of the minimal functional unit of an agonist ligand and the wild-type G protein-coupled cholecystokinin (CCK) receptor, using photoaffinity labeling with a CCK analogue probe incorporating dual photolabile benzoylphenylalanine (Bpa) residues as sites of covalent attachment. This probe, 125I-d-Tyr-Gly-[(Nle28,31, Bpa29,33)CCK-26-33], was shown to represent a full agonist and to specifically label the CCK receptor. Like probes incorporating individual photolabile residues in these positions,1,2 the two Bpa residues in the dual photoprobe covalently labeled receptor domains in the amino-terminal tail outside TM1 and in t...
Representations without rules, connectionism and the syntactic argument

Terry Horgan and John Tienson have suggested that connectionism might provide a framework within which to articulate a theory of cognition according to which there are mental representations without rules (RWR) (Horgan and Tienson 1988, 1989, 1991, 1992). In essence, RWR states that cognition involves representations in a language of thought, but that these representations are not manipulated by the sort of rules that have traditionally been posited. In the development of RWR, Horgan and Tienson attempt to forestall a particular line of criticism, theSyntactic Argument, which would show RWR to be inconsistent with connectionism. In essence, the argument claims that the node-level rules of connectionist networks, along with the semantic interpretations assigned to patterns of activation, serve to determine a set of representation-level rules incompatible with the RWR conception of cognition. The present paper argues that the Syntactic Argument can be made to show that RWR is inconsistent with connectionism.
Leader Legitimacy, Leader-Follower Interaction, and Followers' Ratings of the Leader

Summary A leader's legitimacy from appointment or election has been found to have distinctive effects on leader-follower relations in an American context. To examine this process further, an experiment was conducted with 21 groups of male college students organized into groups of four. Ss were assigned a group decision-making task regarding urban problems. After an initial interaction period, in seven groups for each condition, leaders were either appointed by the E, elected by the group, or not formally designated. Groups were observed throughout by two observers independently, from behind a one-way mirror. Significant effects were found in the observed interactions, and on followers' ratings of leaders on a postinteraction questionnaire. As hypothesized, elected leaders were seen by followers as more responsive to followers' needs, more interested in the group task, and more competent than leaders who were appointed. Elected leaders were considered more favorably as future leaders, when contributing to ...
Finite element analysis and experimental verification of SOI waveguide bending loss

Bending and transition losses in silicon-on-insulator rib waveguides were calculated using finite-element analysis of equivalent straight waveguides with perfectly matched boundary layers. Experimental loss measurements of silicon-on-insulator waveguides with various bend radii reveal that this technique accurately predicts loss and minimum bend radius for efficient design. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 699–702, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24135
Computers and teaching literature: Introduction

One of the most common applications of computers in teaching literature involves the use of hypertext/ hypermedia. In this collection several articles discuss instructional uses of hypertext in the literature classroom. Peter Havholm and Larry Stewart describe projects in which they have students create hypertexts as a means of illustrating intertextual relationships. Charles Davis describes WWW-based hypertext tutorials that he uses to guide his students through the range of background information they need for his courses in biblical literature. Based on his classroom experience, Jonathan Smith critiques Landow's The Dickens Web CD-ROM as a teaching tool; and John and Mildred Boaz describe the process and vicissitudes of creating an instructional multimedia CD-ROM. For my part, I survey and critique these and a dozen other uses of hypertext and hypermedia in the teaching of literature. Several articles also discuss another common application of computers to literature instruction: the use of online discussion. Susan-Marie Birkenstock describes how she uses a MOO as a vehicle to help her students gain a sense of the construction of drama. And Marguerite Jamieson, Rebecca Kajs, and Anne Agee discuss the power of small-group synchronous online discussion to engage their students in discussions of literature. Jamieson, Kajs, and Agee also describe their
Venous thromboembolism in trauma: a local manifestation of systemic hypercoagulability?

Background: The purpose of this study was to evaluate the relative importance of systemic hypercoagulability, pre-existing and acquired risk factors, and specific injury patterns in the development of venous thromboembolism (VTE) after injury. Methods: Injured patients with an Injury Severity Score ≥ 15 were followed with lower extremity venous duplex ultrasonography, prothrombin fragment 1 + 2, and quantitative D-dimer levels at 1 and 3 days and then weekly until discharge. Results: Among 101 patients with a mean Injury Severity Score of 27.3 ± 10.5 followed for 12.4 ± 8.7 days, 28 (27.7%) developed a lower extremity thrombosis, 2 (1.9%) sustained a pulmonary embolism, and 1 (0.9%) had a symptomatic upper extremity thrombosis. Although admission fragment 1 + 2 and D-dimer levels were elevated in 81.4% and 100% of patients, respectively, mean levels were not significantly different in those with or without VTE. VTE was more common (p 40 years, immobilization for > 3 days, spine fractures, and lower extremity fractures. However, only obesity (p = 0.004) and immobilization > 3 days (p = 0.05) were independent predictors of VTE in a multivariate analysis. Conclusion: Although elevated in seriously injured patients, neither markers of activated coagulation nor specific injury patterns are predictive of VTE. Associations with immobilization and obesity suggest that VTE after injury is a systemic hypercoagulable disorder with local manifestations of thrombosis related to lower extremity stasis.
Kinematic differentiation of prosodic categories in normal and disordered language development.

Prosody is complex and hierarchically organized but is realized as rhythmic movement sequences. Thus, observations of the development of rhythmic aspects of movement can provide insight into links ...
Development and implementation of a dedicated postoperative evaluation service to improve compliance of postoperative visits.

Background and Aims: Postoperative patient evaluation is an integral component of perioperative care. An audit of our anesthesia department's records demonstrated a compliance rate of Materials and Methods: This retrospective study examined postoperative follow-up completion rate at a large academic center. Data were collected from 58,000 anesthetics during three periods, between each of which an intervention was introduced. The first period examined completion rate when postoperative evaluations were left to the team performing the anesthetic. During the second period, this task was delegated to groups of anesthesiologists based on surgical subspecialty; these smaller groups utilized rotating residents. The third period examined completion rate after implementation of a postoperative evaluation service. All periods utilized the department's electronics database to identify operative patients. The number of adverse anesthesia events reported was also recorded. Results: A significant difference in the proportions of compliance with postoperative evaluations among all three periods was detected. Compliance was 47% during period one and improved to 66% during period two. During period three, which employed a postoperative evaluation service, compliance was 83%. The number of adverse events reported per month increased significantly following the first study period from 95 reported monthly events to 215 and 201 in the second and third periods, respectively. Conclusion: By creating a dedicated postoperative evaluation service using available technology, we improved postoperative evaluation completion rate from 47% to 83%, and demonstrated a significant increase in the number of adverse events reported. Based on this, we support the deployment of a dedicated service as a quality improvement initiative.
BiCG-FFT T-Matrix method for solving for the scattering solution from inhomogeneous bodies

A BiCG-FFT T-Matrix algorithm is proposed to efficiently solve three-dimensional scattering problems of inhomogeneous bodies. The memory storage is of O(N) (N is the number of unknowns) and each iteration in BiCG requires O(N log N) operations. A good agreement between the numerical and exact solutions is observed. The convergence rate for lossless and lossy bodies of various sizes are shown. It is also demonstrated that the matrix condition number for fine grids is the same as that for coarse grids.
Additive Arithmetic Functions on Arithmetic Progressions

Demonstration d'une inegalite relative aux fonctions arithmetiques additives sur des progressions arithmetiques
Surface and gradiometer coils near a conducting body: the lift-off effect.

Abstract The use of surface coils in magnetic resonance is widespread. Examples include MRI, detection of subsurface aquifers by NMR, and, more recently, landmine detection by nuclear quadrupole resonance. In many of these cases a finite-sized sample to be examined is contained within a larger medium that is a poor electrical conductor, and eddy currents induced by the RF fields provide a loss mechanism that reduces the effective quality factorQof the transmitter and receiver coils. Here the losses induced in a circular surface coil (a horizontal loop antenna) separated a distance from a dissipative medium are calculated and compared to measurements. It is shown that often the overall efficiency of the coil for magnetic resonance can be improved by displacing the coil away from the conducting medium a prescribed “lift-off” distance. The use of a gradiometer as a surface coil is also examined, and it is shown by theory and experiment that in certain circumstances such a gradiometer can be more efficient than a conventional surface coil for inspection of conducting media.
Diagnosing Vascular Causes of Renal Failure

The incidence of renal failure due to vascular diseases is increasing. Two reasons for this are the epidemic of atherosclerotic vascular disease in the aging population and the widespread use of vasoactive drugs that can adversely affect renal function. These vascular causes of renal failure include vasomotor disorders such as that associated with nonsteroidal antiinflammatory drugs, small-vessel diseases such as cholesterol crystal embolization, and large-vessel diseases such as renal artery stenosis. These causes of azotemia are less familiar to physicians than more classic causes, such as acute tubular necrosis, and are less likely to be recognized in their early stages. This article describes the various vascular diseases that impair renal function and outlines the steps necessary to identify them. Although some of these conditions, such as renal artery stenosis, can gradually impair function, the vascular causes of acute renal failure are emphasized in this article. Because the vasculitides primarily cause renal failure through secondary glomerulonephritis, they are mentioned only briefly. Extensive testing is rarely necessary because the cause is usually suspected through syndrome recognition. The diagnosis can then be confirmed by the results of one or two additional tests or by improved renal function after treatment.
Characterization of aerosols produced by pneumatic nebulizers for inductively coupled plasma sample introduction: effect of liquid and gas flow rates on volume based drop size distributions

The effect of liquid sample uptake rate and nebulizer gas flow rate on analyte transport rates and volume based primary and tertiary drop size distributions were studied for two pneumatic, concentric nebulizers with a Scott type spray chamber. Experimentally measured Sauter mean diameters and spans were compared to those predicted by an empirical model. One of the two nebulizers produced analyte transport rates that were a factor of two or more higher than the other nebulizer under all uptake rate and gas flow rates studied, despite that the nebulizers were of the same model. When the sample uptake rate is increased 400% (from 0.4 to 2.0 ml/min) the aerosol transport rate increased by only 60 to 68%. Losses of aerosol of all drop sizes due to secondary and tertiary processes result in a decrease in the sample transport efficiency as the uptake rate is increased. When the nebulizer gas flow rate was increased from 0.4 to 1.0 l/min the analyte transport rate increased more than a factor of five. The increase in analyte transport rate (and efficiency) as the gas flow rate was increased from 0.4 to 0.6 or 0.7 l/min was due to both a larger volume of small primary aerosol drops produced and less severe losses of drops due to secondary and tertiary processes. The relative increase in volume of small primary aerosol drops produced when the nebulizer gas was increased from 0.6 or 0.7 to 1.0 l/min was similar to the relative increase in analyte transport rate. The higher transport rates produced by one of the two nebulizers was due to a higher production/loss ratio due to secondary and tertiary processes for drops of all sizes less than 20 μm in diameter rather than differences in the volume of primary aerosol contained in small drops.
Takotsubo Cardiomyopathy Complicated by Cardiac Tamponade Classic Hemodynamic Findings With a New Disease

An 83-year-old woman with no significant medical history developed acute onset chest pain lasting for 1 hour. Electrocardiography performed by emergency responders showed transient 2-mm high-lateral ST elevations on electrocardiography (Figure 1), and she was brought to the emergency room. She was treated with unfractionated heparin (60-U/kg bolus followed by 12 U/kg/min infusion), the glycoprotein IIb/IIIa inhibitor eptifibatide (180-μg/kg bolus followed by 2-μg · kg−1 · min−1 infusion), and 300 mg of clopidogrel by mouth. She developed severe hypotension that required high-dose parenteral inotropic support and was transferred to the catheterization laboratory for emergency cardiac catheterization. Coronary angiography revealed only minor atherosclerotic disease in a small diagonal branch; left ventriculography demonstrated akinesis of the entire mid to apical portions of the left ventricle, consistent with the “apical ballooning” syndrome, or takotsubo cardiomyopathy (Figure …
Electric propulsion plume simulations using parallel computer

A parallel, three-dimensional electrostatic PIC code is developed for large-scale electric propulsion simulations using parallel supercomputers. This code uses a newly developed immersed-finite-element particle-in-cell (IFE-PIC) algorithm designed to handle complex boundary conditions accurately while maintaining the computational speed of the standard PIC code. Domain decomposition is used in both field solve and particle push to divide the computation among processors. Two simulations studies are presented to demonstrate the capability of the code. The first is a full particle simulation of near-thruster plume using real ion to electron mass ratio. The second is a high-resolution simulation of multiple ion thruster plume interactions for a realistic spacecraft using a domain enclosing the entire solar array panel. Performance benchmarks show that the IFE-PIC achieves a high parallel efficiency of g90%
Guiding and focusing of a nanosecond infrared laser within transient hollow plasma femtosecond filament channels

Long distance guidance and focusing of infrared (IR) nanosecond-pulsed laser light in a hollow plasma channel formed with femtosecond pulsed laser plasma filaments is examined with numerical experiments. Numerical models show that a thick hollow plasma channel can provide low loss long distance (>100 m) guidance of the IR nanosecond-pulsed laser beam. The effectiveness of guidance is determined by the electron number density, thickness of the plasma filament shell and the size of the inner radius of the hollow plasma channel. The hollow plasma channel can be thought of as an open-space optical fibre. The required thickness of the plasma channel with specified electron number density and the inner radius can be estimated with modal analysis, similar to that used for optical fibres. In addition, with a small tapering angle in the hollow plasma channel, the guided light can be moderately focused during long distance propagation. Owing to the rapid decay of electron number density of a plasma channel in free space, the delay time between the generation of the plasma channel and the guided light along with the duration of the guided light are better to be maintained within a few nanoseconds.
Theoretical Study of Potential Energy Surface and Thermal Rate Constants for the C6H5 + H2 and C6H6 + H Reactions

The potential energy surface for the C6H5−H2 system has been calculated with a modified Gaussian-2 method (G2M). The system includes the reactions C6H5 + H2 ⇌ C6H6 + H (1) and H + C6H6 ⇌ C6H7 (2). The computed molecular parameters and energetics are employed to calculate the thermal rate constants for these reactions. For the direct abstraction reaction (1), the energy barrier was found to be 8.8 kcal/mol at our best G2M(rcc,MP2) level of theory, with the tunneling corrected transition-state-theory rate constant k1 = 9.48 × 10-20T2.43 exp(−3159/T) cm3/(molecule s) covering 300−5000 K. This result is consistent with scattered kinetic data available in the literature. For the addition reaction (2), the barrier was found to be 8.9 kcal/mol. The rate constant calculated by solving the master equation, with tunneling corrections based on the RRKM theory, gave k2 = 5.27 × 10-11 exp(−1605/T) cm3/(molecule s) at the high-pressure limit and 300 ≤ T ≤ 1000 K. In this temperature regime, where most addition kinetics...
Effect of warping rigidity on stability of a bar under eccentric follower force

Abstract Stability of a cantilever under an eccentrically applied follower-end-load is considered. It is shown that a bar with warping rigidity may lose stability by bending-torsional flutter, bending-torsional buckling, transverse flutter, or torsional buckling depending on the eccentricity and other parameters. In particular, it is found that the bending-torsional-flutter-load can be considerably reduced when the bar has warping rigidity. The influence of the internal damping forces on the flutter loads is also assessed.
Attenuation Correction and Hydrometeor Classification of High-Resolution, X-band, Dual-Polarized Mobile Radar Measurements in Severe Convective Storms

Abstract X-band and shorter radar wavelengths are preferable for mobile radar systems because a narrow beam can be realized with a moderately sized antenna. However, attenuation by precipitation becomes progressively more severe with decreasing radar wavelength. As a result, X band has become a popular choice for meteorological radar systems that balances these two considerations. Dual-polarization provides several methods by which this attenuation (and differential attenuation) can be detected and corrected, mitigating one of the primary disadvantages of X-band radars. The dynamics of severe convective storms depend, to some extent, on the distribution and type of hydrometeors within the storm. To estimate the three-dimensional distribution of hydrometeors using X-band radar data, it is necessary to correct for attenuation before applying commonly used hydrometeor classification algorithms. Since 2002, a mobile dual-polarized Doppler weather radar designed at the University of Massachusetts, Amherst has ...
Emotional arousal as a source of bounded rationality

Abstract This paper proposes an alternative psychological explanation for bounded rationality. According to Herbert Simon, bounded rationality arises from human cognitive limitations. Following the suggestion of institutional economist John R. Commons, I argue that extremes in emotional arousal also contribute to bounded rationality. This idea is formalized and developed using the Yerkes–Dodson law from psychology. Examples from the popular press and the academic literatures of law, management and economics are presented to illustrate the impact of this type of bounded rationality on human behavior.
The effects of dietary conjugated nonadecadienoic acid on body composition in mice

A 19-carbon conjugated diene, conjugated nonadecadienoic acid (CNA), inhibited heparin-releasable lipoprotein lipase and reduced lipid stores in 3T3-L1 adipocytes similarly to conjugated linoleic acid (CLA). When fed to growing mice (0.3% of diet) CNA reduced body fat by 81% whereas CLA reduced body fat by 25%. CLA and CNA differ in length by one carbon atom so they are unlikely to share a common metabolite to account for these observations.
Net returns from 12 cropping systems containing sugarbeet and navy bean

Considerable research has been conducted evaluating yield relationships among crops in various rotations and cropping systems. To compare cropping systems of different lengths of rotation and with different crops, however, a common measurement is needed. This paper evaluates annual net return to land and unallocated resources (ANR) from various cropping systems containing sugarbeet (Beta vulgaris L.), navy bean (Phaseolus vulgaris L.), corn (Zea mays L.), oat (Avena sativa L.), and alfalfa (Medicago sativa L.). Gross returns using representative crop prices are calculated for each cropping system for yield data from a 15-yr cropping systems study conducted on a Misteguay silty clay soil in the Saginaw Valley of Michigan. Costs in 1991 dollars of agricultural inputs, machinery ownership, repairs, maintenance, fuel, and wages are used to calculate expenses. ANR is calculated by subtracting pre- and postharvest operating costs plus machinery ownership costs from gross income for two farm sizes and two sugarbeet prices. With sugarbeet priced at $36/ton, systems with the greatest proportion of sugarbeet and also including navy bean have the highest ANR. The relative ranking of a cropping system's ANR did not change appreciably when farm size increased from 600 to 1000 acres. A sensitivity analysis shows that sugarbeet priced at or below $18/ton caused the relative ranking of the systems to shift and navy bean to become a more dominant factor in the ANR of these systems. While short rotations for sugarbeet and navy bean production may result in lower crop yields, the high economic return of these crops is probably the major reason growers do not employ longer rotations
Effects of Oral Dosing Paradigms (Gavage Versus Diet) on Pharmacokinetics and Pharmacodynamics

Abstract In cancer chemopreventive studies, test agents are typically administered via diet, while the preclinical safety studies normally employ oral gavage dosing. Correspondence in pharmacokinetic and pharmacodynamic profiles between the two dosing approaches cannot be assumed a priori. Sulindac, a non-steroidal anti-inflammatory agent with potential chemopreventive activity, was used to assess effects of the two oral dosing paradigms on its pharmacokinetics and pharmacodynamics. Time-dependent concentrations of sulindac and its sulfone metabolite were determined in plasma and potential target organ, mammary gland. Prostaglandin E2 was used as a pharmacodynamic biomarker and measured in mammary gland. An inverse linear relationship was detected between pharmacodynamic and pharmacokinetic markers, area under the curve for prostaglandin E2 levels and sulindac sulfone concentrations, respectively, in the mammary tissue. Marked differences in pharmacokinetics and pharmacodynamics were observed after administration of sulindac by the two oral dosing paradigms. In general, oral gavage resulted in higher peak and lower trough concentrations of sulindac in plasma and mammary tissue, higher area under concentration–time curve in plasma and mammary tissue, and greater effect on prostaglandin E2 levels than the corresponding diet dosing. This study illustrates potential pitfalls and limitations in trying to generalize based on data obtained with different oral dosing schemes and their extrapolation to potential efficacy and health risks in humans.
Marital status of persons with spinal cord injury.

Abstract The proposition that persons are selected into and out of marriage on the basis of their health or disability status has often been advanced, but remains untested. This article (1) presents a theoretical rationale for the proposition; (2) provides an initial test of that proposition by comparing the marital status of a sample of persons with spinal cord injury with the marital status of the general public; and (3) elaborates on the proposition by examining the extent to which other factors account for differences in marital status among members of this disabled group. The selected factors were sex, severity of disability (indicated by need for assistance, perceived health, and extent of paralysis), socio-economic status (indicated by adequacy of income and welfare status), current age, and age at onset of disability. A secondary analysis of existing survey data on 251 Oregon residents with spinal cord injury (182 males, 69 females) yielded the following results. (1) The marital selection proposition was supported in that the marital status of this sample differed markedly from that of the general population. (2) The disability exerted a greater effect on the marital status of females than of males. (3) All the selected variables were significantly associated with marital status for one or for both sexes. Discriminant function analyses, employing these variables, identified correctly the marital status of 67.6% of the males, and 75.4% of the females. (4) Profiles of married, formerly married, and single men and women with spinal cord injury are presented. Suggestions are offered for further testing of the marital selection proposition and for elaborating theory linking disability and health status to marital status.
Hypothalamic prostaglandin E2 during lipopolysaccharide-induced fever in guinea pigs

Prostaglandin E2 (PGE2) is postulated to be a central mediator of fever. It is generally believed that it is produced in the preoptic area of the anterior hypothalamus (POA) because, among other evidence, its level increases both in the third ventricle and in the POA in response to pyrogens. However, lately, the question has arisen whether PGE2 might, in fact, be formed outside of the brain substance and then penetrate it, in particular through the organum vasculosum laminae terminalis. If produced outside the brain substance, the peripheral blockade of its synthesis should prevent lipopolysaccharides (LPS)-induced fever, whereas the intracarotid infusion of PGE2 should produce an increase in core temperature (T(C)) as well as in preoptic PGE2. To verify this hypothesis, continuous measurements of T(C) and preoptic PGE2 levels were made in conscious guinea pigs administered the PGE2 synthase inhibitor, indomethacin (10 or 50 mg/kg, im) 30 min before S. enteritidis LPS (2 mu g/kg, iv) or before PGE2 microdialyzed into the POA (1 mu g/mu l at 2 mu g/min for 2.5 h) and during PGE2 infused into a carotid artery (1 mu g and 10 mu g/mu l at 2 mu g/min for 1 h). LPS induced a biphasic 1.4 degrees C fever that was consistently associated with an increase in the level of PGE2 in the POA. Indomethacin at 10 mg/kg attenuated the course of the LPS-induced fever and prevented the associated increase in preoptic PGE2 for 90 min after fever onset; thereafter, PGE2 was significantly reduced by comparison with controls. Indomethacin at 50 mg/kg completely abolished both the fever and the increased levels of PGE2 in the POA; the fever induced by PGE2 microdialyzed into the POA was not affected by indomethacin pretreatment The intracarotid infusion of PGE2 produced T(C) falls and no increase in preoptic PGE2 levels. The indomethacin-induced blockade of fever and inhibition of the associated increase in preoptic PGE2 levels further substantiates the presumptive link between PGE2 in the POA and fever caused by LPS. The failure of exogenous PGE2 infusion to induce increases in T(C) and preoptic PGE2 levels excludes the possibility that PGE2 formed outside of the brain penetrates the POA and induces fever. Thus, in guinea pigs, the PGE2 associated with LPS-induced fever may be synthesized in the POA.
Dynamic packet fragmentation for wireless channels with failures

It was shown recently [7-9], under quite general conditions, that retransmission-based protocols may result in power-law delays and possibly zero throughput even if the distribution of packets (data units) is very concentrated, e.g., exponential or Gaussian. This phenomenon occurs irrespective of whether the cause of retransmissions is due to channel failures in the data link layer [7] or collisions in ALOHA-type protocols in the MAC layer [9]. These theoretical findings are in agreement with empirical measurements in [18], showing that the utilization of the 802.11 protocol is only 40%, basically due to retransmissions.In order to alleviate this problem, we propose a new dynamic packet fragmentation algorithm that can adaptively match channel failure characteristics. This algorithm is based on the mathematical insights developed in [7, 8]. As a first order approximation to the channel dynamics, we assume that the channel is either available for a period of time or unavailable. Then, our fragmentation algorithm divides the original packets into smaller ones whose size is bounded by the kth largest value among the last k+m channel availability periods. We also discuss mechanisms for aggregating smaller packets into larger ones, which, in combination with fragmentation, can further improve the performance.Under the renewal assumptions on the channel dynamics, we prove that our fragmentation method results in k additional moments for the total transmission time until all the fragments are successfully transmitted, i.e., the transmission time has a much more concentrated distribution and, in particular, the channel will always have a positive throughput. In addition, we argue that by tuning the parameter m, the number of introduced new packets can be kept reasonably small as well. Furthermore, we demonstrate through simulations that the superior performance of our fragmentation algorithm extends beyond the renewal assumptions used in the analysis to time varying and/or correlated channels. For practical implementation of the algorithm, we also discuss approaches to measuring the channel availability periods, especially in situations when the channel dynamics may not be directly observable.It is worth mentioning that our algorithm can be used for designing efficient checkpointing schemes in other systems that are prone to failures, e.g., distributed computing systems.
In vitro assessment of a combined radiofrequency ablation and cryo-anchoring catheter for treatment of mitral valve prolapse

Percutaneous approaches to mitral valve repair are an attractive alternative to surgical repair or replacement. Radiofrequency ablation has the potential to approximate surgical leaflet resection by using resistive heating to reduce leaflet size, and cryogenic temperatures on a percutaneous catheter can potentially be used to reversibly adhere to moving mitral valve leaflets for reliable application of radiofrequency energy. We tested a combined cryo-anchoring and radiofrequency ablation catheter using excised porcine mitral valves placed in a left heart flow loop capable of reproducing physiologic pressure and flow waveforms. Transmitral flow and pressure were monitored during the cryo-anchoring procedure and compared to baseline flow conditions, and the extent of radiofrequency energy delivery to the mitral valve was assessed post-treatment. Long term durability of radiofrequency ablation treatment was assessed using statically treated leaflets placed in a stretch bioreactor for four weeks. Transmitral flow and pressure waveforms were largely unaltered during cryo-anchoring. Parameter fitting to mechanical data from leaflets treated with radiofrequency ablation and cryo-anchoring revealed significant mechanical differences from untreated leaflets, demonstrating successful ablation of mitral valves in a hemodynamic environment. Picrosirius red staining showed clear differences in morphology and collagen birefringence between treated and untreated leaflets. The durability study indicated that statically treated leaflets did not significantly change size or mechanics over four weeks. A cryo-anchoring and radiofrequency ablation catheter can adhere to and ablate mitral valve leaflets in a physiologic hemodynamic environment, providing a possible percutaneous alternative to surgical leaflet resection of mitral valve tissue.
The ISX-JET beryllium limiter experiment☆

Abstract A description is given of an experiment that has been designed for the ISX-B tokamak at the Oak Ridge National Laboratory using beryllium as the primary plasma limiter.
Hepatic and Ductus Venosus Blood Flows During Fetal Life

The course of the venous circulation in the fetal liver has been studied in fetal lambs by means of the radionuclide-labeled microsphere technique. About 50% of umbilical venous blood passes through the ductus venosus, while the remainder is distributed to both lobes of the liver. Portal venous blood is largely distributed to the right lobe of the liver, with a small proportion passing through the ductus venosus and none to the left lobe. Because of these flow patterns, oxygen saturation is lower in the right than in the left hepatic vein. Left hepatic venous blood joins the ductus venosus stream and these preferentially pass through the foramen ovale, whereas right hepatic venous blood joins the distal inferior vena caval stream and preferentially passes through the tricuspid valve. These patterns favor distribution of well-oxygenated blood to the fetal heart and brain. Hypoxia and reduced umbilical venous return are associated with reduced flow through the hepatic microcirculation with proportionately greater ductus venosus flow. In the fetus, the liver has a major role in influencing venous return to the heart and in regulating distribution of oxygen and energy substrate supply to different fetal organs.