cssi/SciSciGPT-SciSciNet huggingface dataset:
Long-term outcomes of primary angioplasty and primary stenting of central venous stenosis in hemodialysis patients

Introduction Central (superior vena cava, brachiocephalic, or subclavian) venous stenoses are a major impediment to long-term arteriovenous access in the upper extremities. The optimal management of these stenoses is still undecided. The purpose of this study was to determine the outcomes of primary angioplasty (PTA) vs primary stenting (PTS) in a dialysis access population at a tertiary referral academic medical center. Methods A database of consecutive hemodialysis patients undergoing endovascular treatment for central venous stenosis was developed for the period 1995 through 2003. This database was retrospectively reviewed. Vessels exposed to either primary high-pressure balloon angioplasty or primary stenting were examined. Vessels undergoing stenting after failed or suboptimal angioplasty were defined as failures at the time of stenting despite the potential continued patency upon completion of stenting. Kaplan-Meier survival analyses were performed to assess time-dependent outcomes. Cox proportional hazards analysis was performed for time-dependent variables. Data are presented as mean ± standard deviation where appropriate. Results PTS was used to treat 26 patients (35% male; average age, 57 ± 15 years) with 26 central venous stenoses, and 47 patients (45% male; average age, 57 ± 18 years) with 49 central venous stenoses were treated with PTA. The PTS group underwent 71 percutaneous interventions per stenosis (average, 2.7 ± 2.4 interventions), and the PTA group underwent 98 interventions per stenosis (average, 2.0 ± 1.6 interventions). The PTS group hemodialysis access site was an average of 1.0 ± 1.3 years old at the time of the initial intervention, and the hemodialysis access in the PTA group was an average of 1.1 ± 1.2 years old. Primary patency was equivalent between groups by Kaplan-Meier analysis, with 30-day rates of 76% for both groups and 12-month rates of 29% for PTA and 21% for PTS ( P = .48). Assisted primary patency was also equivalent ( P = .08), with a 30-day patency rate of 81% and 12-month rate of 73% for the PTA group, vs PTS assisted patency rates of 84% at 30 days, and 46% at 12 months. Ipsilateral hemodialysis access survival was equivalent between groups. Conclusions Endovascular therapy with PTA or PTS for central venous stenosis is safe, with low rates of technical failure. Multiple additional interventions are the rule with both treatments. Although neither offers truly durable outcomes, PTS does not improve on the patency rates more than PTA and does not add to the longevity of ipsilateral hemodialysis access sites.
Rice Weevil Damage to Stored Corn

One of the most destructive insect pests of stored corn in North Carolina is the rice weevil, Sitophilus oryza (L.). No accurate figures on the amount of damage caused by this pest under North Carolina conditions have been available. This study attempts to determine not only the weight losses occasioned by the weevil but also the loss in nutritive value that results from weevil attack. Weevil damage and weight loss were determined in single kernels of corn as well as in lots of 20 and 250 grams stored at 60°, 70°, and 80° F. Nutritive losses were determined in 20- and 250-gram lots of corn by chemical analysis and by feeding tests on mice. The total loss in weight of corn was directly proportional to the number of weevils in the corn. The greatest loss occurred at 80° F. in each of the storage tests. In the single-kernel test, weevils were responsible for loss in weight of 74.7%; in the 20- gram test they caused a loss of 12.9%, and in the 250-gram test 25.9%. The protein content of the corn increased with a corresponding increase in weevil infestation. Mice ate less and showed the least gain in weight on meal prepared from heavily infested corn.
The impact of context manipulations on movement patterns during a transition period

Abstract According to principles of dynamic systems theory, behavior is both unstable and more easily shifted into new patterns during transitional periods than during stable periods. We examined this principle by analyzing the stepping response of infants when they were in a transitional period of treadmill stepping. We tested 12 infants with Down syndrome (M age=13.3 months) by supporting them upright on a small treadmill in the traditional protocol and in four manipulations of this context. All the infants were, developmentally, at a point of producing few steps and multiple step types when on the treadmill. We used context manipulations that we predicted would shift infants' behaviors into a dominance of alternating steps over other step types and would increase the number of steps produced overall. Context manipulations included Velcro, nubbly, girdle, and weights. Our results showed that infants produced more total steps and more alternating steps in the altered conditions compared to baseline. The effectiveness of each manipulation varied; the Velcro context tended to have the strongest impact overall. Changes in context also significantly affected the trajectory of foot displacement in swing. Our results illustrate the importance of (a) extrinsic factors on the developmental trajectory we observe in motor behavior over time and (b) understanding behavior during transitional as well as in stable periods. Psyc INFO classification : 2330; 2800
Distribution of free and conjugated dopamine in human caudate nucleus, hypothalamus, and kidney.

Abstract: The occurrence of free and conjugated dopamine was determined by HPLC in human caudate nucleus, hypothalamus, and kidney. Free norepinephrine and dihydroxyphenylacetic acid levels in some tissues were also determined. Conjugated dopamine was found to account for 25% of the total DA in the kidney. Conjugated DA accounted for 2.9% and 5.1% of the total DA in the caudate nucleus and hypothalamus, respectively. These results indicate that conjugated dopamine is not homogenously distributed in human tissue.
CCAAT/enhancer-binding protein-β has a role in osteoblast proliferation and differentiation

CCAAT/enhancer binding protein beta (C/EBPbeta) is known to play an important role in the expression of several genes necessary for bone development and homeostasis including osteocalcin, IGF-1, and IL-6. In this study, we show that C/EBPbeta protein levels and, consequently, DNA-binding activity are temporally regulated, dramatically decreasing upon differentiation of MC3T3-E1 mouse osteoblasts. Corresponding with these results, the constitutive expression of C/EBPbeta LAP in MC3T3-E1 osteoblasts increased proliferation and suppressed osteogenic differentiation. Thus, C/EBPbeta LAP not only appears to participate in the regulation of genes associated with mature bone physiology, but is also a critical regulator of osteoblast growth and differentiation.
STM investigation of energetic insertion during direct ion deposition

Thin copper films have been deposited on single crystal copper substrates and characterized using a UHV Scanning Tunneling Microscope to probe the effect of atomic insertions during hyperthermal ion deposition. At low temperatures, atomic insertions are predicted to provide a net downhill current that offsets the roughening effect due to uphill “Schwoebel” currents leading to a net smoothing of the surface. Films have been grown at several different energies targeted to observe a crossover from insertion driven smoothing to adatom-vacancy dominated roughening. Copper thin films are deposited near 20 eV using a mass selected ion deposition system that allows precise control (+/− 2 eV) over the energy of constituent atoms. Experimental observations are compared with a sophisticated Kinetic Monte Carlo and Molecular Dynamics hybrid (KMC-MD) simulation.
13C and 15N spin-lattice relaxation and chemical shift studies of pentane-2,4-diamine

13C and 15N NMR chemical shift and spin–lattice relaxation data have been measured for both meso- and racemic-pentane-2,4-diamine. At high pH (12), relaxation is consistent with hindered rotation of the NH2 group due, in part, to the formation of intramolecular hydrogen bonds. At low pH (2), relaxation is consistent with relatively unhindered rotation of the NH3+ group. Rotational jump rates and barriers are reported, determined from the NT1 ratios between 15N and 13C nuclei. In all cases, the ratios for the racemic diastereomer are higher than those of the meso compounds; this is interpreted in terms of conformationally more stable intramolecular hydrogen bond formation in the meso compound. Chemical shifts for the diastereomeric amines show that 15N shifts move downfield on protonation along with methyl and methylene carbons, while the methine carbon resonances move upfield.
Social networks and the internationalization of Chinese entrepreneurs

Chinese privately owned, small and medium-sized enterprises (SMEs) are rapidly internationalizing, yet little research has been reported about how these entrepreneurs manage decisions during internationalization. This study investigates how social networks (guanxi) are used when making strategic, competitive, and marketing decisions. Interviews in China with a small sample of SME entrepreneurs revealed that cultural and ethnic factors play a surprisingly important role in their successful internationalization. In the article, we discuss managerial implications for successful internationalization of Chinese entrepreneurs, we question the completeness of current theories on the internationalization process, and we propose specific directions for future research. © 2009 Wiley Periodicals, Inc.
Rapid drop in serum iron concentration associated with stress.

Abstract In order to further identify the stressful conditions associated with a sudden, pronounced drop in serum iron concentration, a concomitant rise in white blood cell count was utilized to select the charts of 47 patients for review. These patients were grouped into the four categories of surgical, infectious, neurologic, and obstetric events. The rapid drop in serum iron concentration appeared to be a non-specific response to a variety of stressful situations, and possible mechanisms are discussed.
Post-Conflict Reconstruction and the Challenge to International Organizations: The Case of El Salvador

Abstract Countries in post-conflict transitions have to reconcile the development challenge with the additional burden of reconstruction and national reconciliation. This paper first describes the peculiarities of these countries which make them clearly different from those pursuing normal development. Second is a discussion of the challenges that these transitions pose on the countries involved and on the international organizations that support them. Third, the paper illustrates through a discussion of El Salvador—by all standards a success story—how the International Monetary Fund and the United Nations had to adapt to meet the challenges of post-conflict reconstruction. The paper concludes with some policy recommendations.
Spatially Resolving Ocean Color and Sediment Dispersion in River Plumes, Coastal Systems, and Continental Shelf Waters

Satellite remote sensing of ocean color in dynamic coastal, inland, and nearshorewaters is impeded by high variability in optical constituents, demands specialized atmospheric correction, and is limited by instrument sensitivity. To accurately detect dispersion of bio-optical properties, remote sensors require ample signal-to-noise ratio (SNR) to sense small variations in ocean color without saturating over bright pixels, an atmospheric correction that can accommodate significantwater-leaving radiance in the near infrared (NIR), and spatial and temporal resolution that coincides with the scales of variability in the environment. Several current and historic space-borne sensors have met these requirements with success in the open ocean, but are not optimized for highly red-reflective and heterogeneous waters such as those found near river outflows or in the presence of sediment resuspension. Here we apply analytical approaches for determining optimal spatial resolution, dominant spatial scales of variability ("patches"), and proportions of patch variability that can be resolved from four river plumes around the world between 2008 and 2011. An offshore region in the Sargasso Sea is analyzed for comparison. A method is presented for processing Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra imagery including cloud detection, stray lightmasking, faulty detector avoidance, and dynamic aerosol correction using short-wave- and near-infrared wavebands in extremely turbid regions which pose distinct optical and technical challenges. Results showthat a pixel size of approx. 520 mor smaller is generally required to resolve spatial heterogeneity in ocean color and total suspended materials in river plumes. Optimal pixel size increases with distance from shore to approx. 630 m in nearshore regions, approx 750 m on the continental shelf, and approx. 1350 m in the open ocean. Greater than 90% of the optical variability within plume regions is resolvable with 500 m resolution, and small, but significant, differences were found between peak and nadir river flow periods in terms of optimal resolution and resolvable proportion of variability.
Light catalyzed substitution and disproportionation in [(π-C5H5)Mo(CO)3]2

Abstract The metal—metal bonded molybdenum dimer [(π-C 5 H 5 )Mo(CO) 3 ] 2 undergoes an efficient light-catalyzed reaction with X − (X is Cl, Br, or SCN) in acetone, acetonitrile, or tetrahydrofuran: The reaction, which is a net disproportionation [Mo 2 I → Mo II + Mo 0 ], is followed by a second light-catalyzed step in which CO is displaced from (π-C 5 H 5 )Mo(CO) 3 X giving (π-C 5 H 5 )Mo(CO) 2 X 2 − . The electronic spectrum of [(π-C 5 H 5 )Mo(CO) 3 ] 2 in acetone has two well separated bands at λ max 382 nm (ϵ18,300) and λ max 500 nm (ϵ1610). The wavelength dependence of the initial reaction (X = Cl) is remarkable, Φ 546 = 0.36 ± 0.06 and Φ 366 = 0.07 ± 0.02, since it indicates that the upper excited states are less reactive than the lower. The efficiencies of the photoreactions between [(π-C 5 H 5 )Mo(CO) 3 ] 2 and X − or L (L is a tertiary phosphine or phosphite) are all strongly solvent dependent.
Kilopixel backshort-under-grid arrays for the Primordial Inflation Polarization Explorer

We have demonstrated a kilopixel, filled, infrared bolometer array for the balloon-borne Primordial Inflation Polarization Explorer (PIPER). The array consists of three individual components assembled into a single working unit: 1) a transition-edge-sensor bolometer array with background-limited sensitivity, 2) a quarter–wavelength backshort grid, and 3) an integrated Superconducting Quantum Interference Device (SQUID) multiplexer (MUX) readout. The detector array is a filled, square–grid of suspended, one-micron thick silicon bolometers with superconducting sensors. The Backshort–Under–Grid (BUG) is a separately fabricated component serving as a backshort to each pixel in the array. The backshorts are positioned in the cavities created behind each detector by the back–etched well. The spacing of the backshort beneath the detector grid can be set from ~30-300_microns by independently adjusting process parameters during fabrication. Kilopixel arrays are directly indium–bump–bonded to a 32x40 SQUID multiplexer circuit. The array architecture is suitable for a wide range of wavelengths and applications. Detector design specific to the PIPER instrument, fabrication overview, and assembly technologies will be discussed.
Implementation of a macromolecular mechanics program on a cyber 205 supercomputer

Abstract We describe the steps involved in the conversion and vectorization of a macromolecular mechanics program on a CYBER 205 supercomputer. Several programming problems that we have encountered in optimizing a molecular mechanics program for a CYBER 205 are discussed including: the effect of vector length on speed, design of alternative algorithms, the migration of bottlenecks and rate differences obtained for logical vs arithmetic operations. The vectorized code for particular subroutines runs more than 200 times faster on the CYBER 205 as compared with a VAX 11/780. Using an enzyme-inhibitor complex, Rhizopus Chinensis carboxyl protease-pepstatin, containing 2,844 atoms as a model for this type of calculation, we have obtained an overall increase in speed of between 80-120 over a VAX 11/780 equipped with floating point accelerator for the evaluation of the conformational energy and forces on the atoms.
Deletion of Aldose Reductase from Mice Inhibits Diabetes-Induced Retinal Capillary Degeneration and Superoxide Generation

Purpose: Pharmacologic inhibition of aldose reductase (AR) previously has been studied with respect to diabetic retinopathy with mixed results. Since drugs can have off-target effects, we studied the effects of AR deletion on the development and molecular abnormalities that contribute to diabetic retinopathy. Since recent data suggests an important role for leukocytes in the development of the retinopathy, we determined also if AR in leukocytes contributes to leukocytemediated death of retinal endothelial cells in diabetes. Methods: Wild-type (WT; C57BL/6J) and AR deficient (AR 2/2 ) mice were made diabetic with streptozotocin. Mice were sacrificed at 2 and 10 months of diabetes to evaluate retinal vascular histopathology, to quantify retinal superoxide production and biochemical and physiological abnormalities in the retina, and to assess the number of retinal endothelial cells killed by blood leukocytes in a co-culture system. Results: Diabetes in WT mice developed the expected degeneration of retinal capillaries, and increased generation of superoxide by the retina. Leukocytes from diabetic WT mice also killed more retinal endothelial cells than did leukocytes from nondiabetic animals (p,0.0001). Deletion of AR largely (P,0.05) inhibited the diabetes-induced degeneration of retinal capillaries, as well as the increase in superoxide production by retina. AR-deficiency significantly inhibited the diabetes-induced increase in expression of inducible nitric oxide synthase (iNOS) in retina, but had no significant effect on expression of intercellular adhesion molecule-1 (ICAM-1), phosphorylated p38 MAPK, or killing of retinal endothelial cells by leukocytes. Conclusions: AR contributes to the degeneration of retinal capillaries in diabetic mice. Deletion of the enzyme inhibits the diabetes-induced increase in expression of iNOS and of superoxide production, but does not correct a variety of other proinflammatory abnormalities associated with the development of diabetic retinopathy.
Effects of Hemodialysis and of Glucose-Insulin Administration on Plasma Potassium and on the Electrocardiogram

Hypopotassemia was produced in dogs by hemodialysis or by intravenous administration of glucose with insulin. Both methods resulted in a similar decrease in plasma K concentration and similar ECG changes although K was withdrawn from the cells during dialysis while it entered the cells during glucose-insulin infusion. The maximal plasma K decrease occurred after two hours of dialysis or glucose-insulin infusion; administration of glucose-insulin after dialysis resulted in no further plasma potassium decrease. However, dialysis after glucose-insulin infusion caused further lowering of plasma potassium. The ECG changes were evaluated in relation to changes in plasma K concentration. The most consistent effects of hypopotassemia were in decreasing order: increased duration of the QRS complex, increased duration of the QT c interval and increase in amplitude of the P wave. Correlation coefficients (R) between these ECG changes and the plasma K decreases were of the order -0.48 to -0.54. The ECG changes failed to show even a weak correlation with absolute plasma K concentrations or with calculated changes in intracellular K.
Nocturnal increase in pineal melatonin production in two lemming species, Dicrostonyx hudsonius and D. groenlandicus.

Abstract Pineal N -acetyltransferase (NAT) activity and melatonin levels and thyroxine 5′-deiodinase (5′D) activity in brown adipose tissue (BAT) were compared during the day and night in two species of lemmings, Dicrostonyx hudsonius and D. groenlandicus . In both species, NAT and melatonin exhibited significant night-time increases in the pineal gland. Thyroxine 5′D activity in BAT did not show a statistically significant day-night difference in either species of lemming, suggesting the night-time rise in melatonin does not induce a similar increase in BAT 5′D.
Ray geometry in non-pinhole cameras: a survey

A pinhole camera collects rays passing through a common 3D point and its image resembles what would be seen by human eyes. In contrast, a non-pinhole (multi-perspective) camera combines rays collected by different viewpoints. Despite their incongruity of view, their images are able to preserve spatial coherence and can depict, within a single context, details of a scene that are simultaneously inaccessible from a single view, yet easily interpretable by a viewer. In this paper, we thoroughly discuss the design, modeling, and implementation of a broad class of non-pinhole cameras and their applications in computer graphics and vision. These include mathematical (conceptual) camera models such as the General Linear Cameras and real non-pinhole cameras such as catadioptric cameras and projectors. A unique component of this paper is a ray geometry analysis that uniformly models these non-pinhole cameras as manifolds of rays and ray constraints. We also model the thin lens as a ray transform and study how ray geometry is changed by the thin lens for studying distortions and defocusing. We hope to provide mathematical fundamentals to satisfy computer vision researchers as well as tools and algorithms to aid computer graphics and optical engineering researchers.
Answering Questions Requesting Scientific Explanations for Communication

The term explanation has 2 valid senses: as a discursive activity and as the content of that activity. In the first sense, an explanation is an illocutionary act that provides an answer to an “audience” question about why some phenomenon behaves in a particular way. In the second sense, an explanation is the content of that answer. Although natural language philosophers have proposed some conditions for the discursive act of explaining, their proposals must be combined with some insights provided by scientific realists to distinguish what is specific to scientific, as distinguished from everyday, explanation. There are 2 major types of scientific explanation, causal and functional. An ideal scientific understanding of any communicative phenomenon requires both causal and functional accounts because the 2 work together to provide the types of knowledge that practitioners need to empower themselves and reach their goals as communicators.
Comparing the Acidities of Microporous Aluminosilicate and Silico-Aluminophosphate Catalysts: A Combined Quantum Mechanics-Interatomic Potential Function Study

DFT-B3LYP calculations are performed on 4-ring models of aluminophosphates (AlPOs) and silico-aluminophosphates (SAPOs). The results are used to fit the parameters of ion pair shell model potential functions. The potentials obtained are tested in lattice energy minimizations for berlinite and the microporous materials AlPO-18, AlPO-40, AlPO-52, and VPI-5. Not only does the potential reproduce the observed structures (average error of the cell constants 1.3%), it also predicts vibrational frequencies over the whole frequency range equally well (maximum deviation 50 cm -1 ). The potential is used to predict the structures and properties of Bronsted acid sites in an aluminosilicate and a SAPO with the chabazite framework structure (HSSZ-13 and HSAPO-34). A new combined quantum mechanics-intermolecular potential function approach (QM-Pot) is used at the DFT level. Comparison is made with full periodic DFT calculations using plane wave basis sets. The deprotonation energies corrected for systematic errors of the methods used are 1 231-1 235 and 1 261-1 280 kJ/mol for HSSZ-13 and HSAPO-34, respectively. The same acid site has a lower acidity in a SAPO than in an aluminosilicate zeolite of the same structure.
The Bulk Service Queue with a General Control Strategy: Theoretical Analysis and a New Computational Procedure

This paper develops a general framework for analyzing a wide class of vehicle dispatching strategies for bulk arrival, bulk service queues. We provide a simple derivation of the queue length transform for the embedded Markov chain, and present a new computational procedure for finding the moments of the queue length distribution. Extensive computational tests demonstrate that the new procedure is significantly faster and more stable than the standard method, from the literature, that requires solving a set of simultaneous linear equations. We give formulas for the mean and variance of the length of the queue for the general case of compound Poisson arrivals, random batch capacities, general service times and a general control strategy.
Behavior of hamster sperm nuclei incorporated into eggs at various stages of maturation, fertilization, and early development. The appearance and disappearance of factors involved in sperm chromatin decondensation in egg cytoplasm.

Golden hamster eggs at various stages of maturation, fertilization, and early development were freed from the zona pellucida and inseminated in vitro with capacitated, acrosome-reacted spermatozoa. Electron microscopic observations showed that the spermatozoa were capable of fusing with eggs in all stages from the germinal vesicle stage through the four-cell stage. The ability of the eggs to fuse with the spermatozoa was high throughout all stages of maturation, decreased slightly following fertilization, and was markedly reduced after the first cleavage division. Eggs beyond the four-cell stage were incapable of fusing with spermatozoa. The ability of the egg cytoplasm to decondense sperm chromatin first appeared about the time of the breakdown of the germinal vesicle, increased with the progression of nuclear maturation, reached a maximum at the time of ovulation, diminished following fertilization, reappeared during the first cleavage division, and disappeared again after the completion of the division. It appears that the factors of conditions which cause the decondensation of sperm chromatin appear (or become active) only during a certain period of the cell cycle. The possible chemical nature and origin of the factors responsible for the decondensation of sperm chromatin within the egg cytoplasm were discussed.
Protein Crystallization: Specific Phenomena and General Insights on Crystallization Kinetics

Experimental and simulation studies of the nucleation and growth kinetics of proteins have revealed phenomena that are specific for macromolecular crystallization, and others that provide a more detailed understanding of solution crystallization in general. The more specific phenomena, which include metastable liquid-liquid phase separations and gelation prior to solid nucleation, are due to the small ratio of the intermolecular interaction-range to the size of molecules involved. The apparently more generally applicable mechanisms include the cascade-like formation of macrosteps, as an intrinsic morphological instability that roots in the coupled bulk transport and nonlinear interface kinetics in systems with mixed growth rate control. Analyses of this nonlinear response provide (a) criteria for the choice of bulk transport conditions to minimize structural defect formation, and (b) indications that the "slow" protein crystallization kinetics stems from the mutual retardation of growth steps.
Recovery Functions of Somatosensory Peripheral Nerve and Cerebral Evoked Responses in man

Abstract 1. 1. This study was conducted to obtain additional data concerning early recovery of human somatosensory and peripheral nerve responses and to determine the relation between recovery at these levels. In eleven subjects, using an averaging procedure for recording, recovery functions of median nerve and cerebral evoked responses were determined simultaneously. Equal intensity conditioning and test stimuli were suprathreshold for sensation and subthreshold for motor response. The numerous interstimulus intervals tested ranged from 1 to 100 msec. 2. 2. Nerve recovery function results corresponded closely to those obtained by previous workers. Relative refractoriness lasted about 4 msec, was followed by a period of supernormality, and then by subnormality of variable duration (up to 100 msec). 3. 3. Commencing with the initial peak negativity of the cerebral response (latency about 20 msec), six successive points of inflection were identified; the latencies of these points were determined and amplitudes were measured between them. During recovery there was a progressive reduction in latency of all points; latency recovery was usually complete at about 20 msec. Amplitude recovery was more variable. Most subjects showed one or more peaks of full amplitude recovery or facilitation before 20 msec, followed by a period of diminished responsiveness between 20 and 40 msec, and a subsequent return of responsiveness. 4. 4. Intercorrelations between the nerve and cerebral response component recovery functions yielded no coefficient which could account for more than 3% common variance. The influence of peripheral factors on cerebral recovery functions thus appears negligible. 5. 5. Intercorrelations between amplitude recovery functions of the cerebral response components were nearly all statistically significant, but slight in magnitude. This suggests that the various components reflect relatively independent processes.
UV vapor generation for determination of selenium by heated quartz tube atomic absorption spectrometry.

A new vapor generation technique utilizing UV irradiation coupled with atomic absorption for the determination of selenium in aqueous solutions is described. In the presence of low molecular weight organic acid solutions, inorganic selenium(IV) is converted by UV irradiation to volatile selenium species, which are then rapidly transported to a heated quartz tube atomizer for detection by atomic absorption spectrometry. Optimum conditions for photochemical vapor generation and interferences from concomitant elements were investigated. Identification of the volatile products using cryotrapping GC/MS analysis revealed that inorganic selenium(IV) is converted to volatile selenium hydride, selenium carbonyl, dimethyl selenide, and diethyl selenide in the presence of formic, acetic, propionic, and malonic acids, respectively. In acetic acid solution, the efficiency of generation was estimated to be 50 ± 10%. No interference from Ni2+ and Co2+ at concentrations of 500 and 100 mg L-1, respectively, was evident. A...
Remote plume measurements by use of a correlation spectrometer and a differential absorption lidar

Abstract During several days in 1980 through 1981, Southern California Edison Company (SCE) using its mobile Air Quality Measurements Laboratory (AQML) equipped with a correlation spectrometer (COSPEC) characterized the plume from its 1,500 MW oil-fired power plant located in Southern California. Concurrently, on some of these days, the SRI Differential Absorption Lidar (DIAL) system compared the plume characterization results. It was found that the AQML system can track the plume aloft to the surface impact and beyond, thus characterizing the plume dispersion as a function of distance downwind. The plume heights determined by the COSPEC and the DIAL techniques agreed reasonably well, generally within 20%, whereas the predicted plume heights using the Briggs Formulation for simple atmosphere showed agreement, overestimation or underestimation, depending on the atmospheric stability. Compared to the theoretical values, the plume SO2 fluxes determined by COSPEC were about 30–40% lower and those determined by DIAL technique were 8% lower. Finally, the stack SO2 concentrations estimated by COSPEC and DIAL were 85% and 2% lower, respectively, compared with theoretically calculated values.
Solution of the dam-reservoir interaction problem using a combination of FEM, BEM with particular integrals, modal analysis, and substructuring

Abstract This paper presents a new analysis procedure, which is a combination of the finite element method, the boundary element method with particular integrals, modal analysis and substructuring. The difficulty of the nonsymmetric matrix generally introduced from the boundary element method with nonsymmetric and full matrix at the interface between the finite element and the boundary element methods, is overcome by using the described procedure. A new boundary integral equation, which adopts a frequency-independent fundamental solution, is derived for solving the scalar wave equation. Modal analysis of the dam without the reservoir is first addressed. Then, the modal added-mass and added-loads are calculated by using the boundary element method with particular integrals, to solve the Helmholtz equation along with the boundary conditions, which are functions of modal shapes and generalized coordinates. After obtaining the modal added-mass and added-loads, the dam-reservoir system can be reformed in terms of modal shapes — with the reservoir empty — to obtain the natural frequencies, modal shapes and responses of the total system. Using this procedure, not only can the number of degress-of-freedom of the nonsymmetric, full matrix be significantly reduced, but there is no need to recalculate the properties of the dam without the reservoir when the level of the water changes.
Effect of substrate thickness on radiation properties of coplanar strip antennas

The effect of substrate thickness on the broadband (15–150 GHz) radiation characteristics of exponentially-tapered coplanar-strip antennas is explored using picosecond photoconductive pulse generation and sampling.
Costs of exclusive male parental care in the sea spider Achelia simplissima (Arthropoda: Pycnogonida)

Sea spiders are one of the few marine invertebrates whose males care exclusively for offspring. The costs of parental care, however, have never been addressed for any species of pycnogonid. Costs may be significant for brooding sea spiders of Achelia simplissima, since males carry up to 12 egg masses simultaneously and actively aerate those eggs by moving their ovigerous legs back and forth. This study explored four potential costs to males as a result of parental care: predation, dislodgment, movement and feeding patterns, and frequency of epibionts. Brooding males were found to experience significantly higher frequencies of predator attacks and epibionts, as well as a lower rate of movement compared with nonbrooding males. Interestingly, brooding males were harder to dislodge than nonbrooding males and experienced no change in feeding frequency as a result of parental care. This is the first study to provide evidence that parental care may be costly for male pycnogonids in terms of individual survival and future reproductive success.
An observational and numerical study of a mini-supercell storm

Abstract The structure and evolution of a small, moderately intense supercell storm, observed over northern Alabama on 17 July 1992, is described through a combined observational analysis and numerical modeling study. Wind profiler measurements show that the storm formed within a favorable low-level wind shear regime confined only to northern Alabama over a limited time interval between conventional NWS rawinsonde times. While not severe, this cloud system was long-lived and exhibited characteristics similar to those of classic supercells, including a unicellular echo with multicellular substructures, an extended lifetime, a collar cloud and a flanking line of cumulus. Moreover, this supercell did not produce cloud-to-ground lightning over its lifetime, nor was thunder from intracloud lightning heard over a 20-min period as the storm moved by. Numerical simulations of the cloud system duplicate the general observational features, including horizontal and vertical dimensions, cyclic behavior and convective core and anvil characteristics. Simulated distributions of microphysical fields indicate that a juxtaposition of cloud ice, graupel and supercooled water did not occur in sufficient concentrations to support effective charge separation by the non-inductive charge mechanism, despite updraft magnitudes of 15–20 m s −1 within the −10 to −20°C levels of the cloud.
Hollow core optical fiber deflection for monitoring displacement and load

A novel optical fiber sensor implementation for monitoring structural displacement and load is explored. This new sensor makes use of simple coupling losses between fibers in a hollow core sleeve, and as such, offers variable sensitivity, ruggedness, and design flexibility. Preliminary test results show promise towards the goal of making practical and cost effective fiber optic sensors for field use in structural monitoring. In addition to hardware tests, a computer simulation was written to model sensor performance, and critical design parameters were identified.
Solid phase synthesis of a diketopiperazine catalyst containing the unnatural amino acid (S)-norarginine

Abstract A cyclic dipeptide containing the unnatural amino acid ( S )-norarginine, recently shown to display useful catalytic activity, has been synthesized in good yield and high chemical purity using a solid phase protocol. All reactions in the sequence, including a Hofmann rearrangement and cyclization to diketopiperazine, were performed on the Merrifield polystyrene resin and proceed in high yield. In addition to its improved yield, this new synthesis offers easy access to derivatives and a potential to employ combinatorial strategies to the search for novel catalytic cyclic dipeptides.
Determination of the S2 lifetime of β-carotene

Abstract The S2 lifetime of β-carotene has been determined by both femtosecond transient absorption experiments and emission yield studies. For β-carotene dissolved in ethanol and in CS2, the initially excited S2 was found to live for 200 to 250 fs at room temperature. Implications of this result for carotenoid-to-chlorophyll energy transfer in photosynthetic systems are discussed.
A Preferred Method for Imide Preparation

Abstract In connection with another study, we had need of a simple way to prepare a variety of imides. The purpose of this note is to call attention to an inexpensive, and technically easy, one-pot method of imide preparation.
Low nonzero Reynolds number drag of a thin disk settling axisymmetrically within a cylindrical outer boundary

Measurements have been made of the drag on a thin disk of diameter d moving broadside through a liquid of viscosity μ and density ρ. The liquid is bounded on the outside by a cylindrical tube, diameter D, which is coaxial with the disk. The geometrical parameter ξ=d/D ranges from 0.0189 to 0.112. The Reynolds number Re=ρUd/μ ranges from 0.0167 to 6.89. When the measured values are extrapolated to Re=0, the results agree with the calculations of Shail and Norton. When extrapolated to ξ=0, the results agree with the matched‐asymptotic series solution of Breach for Re<1. A new theoretical result, based upon the Oseen approximation, is obtained for the case in which both inertial effects and boundary effects are included, and the results agree with experiment over the range 4ξ<Re<0.62 as long as ξ<0.05. An empirical scheme is developed to represent our measurements for Re<5 and ξ<0.13. Comparison is made between our results for the drag on a disk and the results of Sutterby for the drag on a sphere.
Effect of thickness on optoelectrical properties of Mo-doped indium oxide films

Abstract Molybdenum-doped indium oxide films of various thicknesses were deposited on quartz substrate by pulsed laser deposition technique. The effect of thickness on structural, optical, and electrical properties was studied. X-ray diffraction studied revealed that all the films are highly oriented along (2 2 2) direction. It is observed that film crystallinity increases with thickness. These films are highly transparent (82–96%) in visible region. Atomic force microscopy analysis shows that the films are very smooth with root mean square surface roughness of 0.95 nm for 10 nm thick film. It is observed that resistivity of the films decreases from 1.05 × 10 −4 Ω cm to 6.06 × 10 −5 Ω cm, while mobility increases from 172 cm 2 /Vs to 263 cm 2 /Vs with increases in film thickness from 10 nm to 125 nm, respectively.
THE COST OF INCLUDING A CALL PROVISION IN MUNICIPAL DEBT CONTRACTS

Municipal bond market studies testing for the effect of a call provision on new-issue borrowing cost fail to examine if the cost of the call provision is sensitive to expected changes in interest rates. This may explain why some studies find that the presence of a call provision increases municipal borrowing costs while others find no effect. Another possible reason for the contradictory findings may be a failure to correct for a self-selection bias that results when some issuers choose to include a call provision and others do not. To correct for the potential self-selection problem, a two-stage probit switching regression technique is used here to estimate the cost of a call provision to municipal issuers. Results indicate municipal issuers pay a premium for the call privilege at the time of issue and that the size of the premium is sensitive to expected changes in interest rates.
Fabricating Consistently Sized Chitosan-Core NanoBioSensors

Doubly labeled chitosan-TPP nanosensors provide a means of studying the effect of nitric oxide and glutamate excitotoxicity in the brain. In order to construct these nanosensors for use in vivo, it is necessary to develop a procedure that results in nanosensor cores of a consistent size. The goal of this project was to investigate various procedures and study the impact of solution temperature, pH, chitosan to TPP ratio, reagent concentration, sonication, and centrifugation on particle size. The optimal procedure involves combining aqueous chitosan and TPP in a 3:1 ratio and stirring at room temperature in 3.33% Acetic acid solution.
An investigation of the material and model parameters for a constitutive model for MSMAs

A two dimensional constitutive model capable of predicting the magneto-mechanical response of a magnetic shape memory alloy (MSMA) has been developed and calibrated using a zero field-variable stress test1. This calibration approach is easy to perform and facilitates a faster evaluation of the three calibration constants required by the model (vs. five calibration constants required by previous models2,3). The calibration constants generated with this approach facilitate good model predictions of constant field-variable stress tests, for a wide range of loading conditions1. However, the same calibration constants yield less accurate model predictions for constant stress-variable field tests. Deployment of a separate calibration method for this type of loading, using a varying field-zero stress calibration test, also didn’t lead to improved model predictions of this loading case. As a result, a sensitivity analysis was performed on most model and material parameters to identify which of them may influence model predictions the most, in both types of loading conditions. The sensitivity analysis revealed that changing most of these parameters did not improve model predictions for all loading types. Only the anisotropy coefficient was found to improve significantly field controlled model predictions and slightly worsen model predictions for stress controlled cases. This suggests that either the value of the anisotropy coefficient (which is provided by the manufacturer) is not accurate, or that the model is missing features associated with the magnetic energy of the material.
Inherent Structures and Two-Stage Melting in Two Dimensions

A large-scale study of the {open_quotes}inherent structures{close_quotes} (IS) associated with equilibrium two-dimensional Lennard-Jones systems is presented. The results validate, for simple 2D fluids, an essential premise of inherent-structures theory: there are consistent, {ital qualitative} differences between the IS associated with distinct equilibrium phases. The hexatic IS show free dislocations plus some nonpercolating grain boundaries. The liquid IS always contain percolating grain boundaries, but no evidence of free disclinations. Our results are consistent with the dislocation-unbinding scenario for the hexatic phase, but leave open the question of the microscopic melting mechanism leading to the isotropic liquid. {copyright} {ital 1997} {ital The American Physical Society}
Fly ash development from sodium, sulphur and silica during coal combustion

Abstract A synthetic coal was made from a furfuryl alcohol polymer with appropriate amounts of sodium, sulphur and silica to duplicate the characteristics of a low rank coal. The synthetic coal was burned in a laminar flow (drop-tube) furnace at 900, 1100, 1300 and 1500 °C. The resulting fly ash particles were quickly quenched, collected and analysed using a scanning electron microscope to determine size and composition. Below 1100 °C, fly ash formation was dominated by coalescence of the mineral matter in the burning particle to form close to one fly ash particle per original coal particle. At higher temperatures, fly ash formation was dominated by fragmentation of the coal/char particle followed by coalescence within the resulting fragments. At the lower temperatures, submicrometre sodium sulphate particles were found adhered to the larger sodium-rich silicate particles. At higher temperatures, the abundance and size of the sodium sulphate particles decreased.
Role of polyoma virus and interferon in a herpes simplex virus infection in vitro.

Abstract A continuous line of mouse embryo cells persistently infected with polyoma virus (carrier culture 23-P) was observed to be resistant to challenge with herpes simplex virus. Resistance was dependent upon the input multiplicity of the herpes virus inoculum. At low multiplicities, the cytopathic effect (CPE) due to herpes virus infection was incomplete, regrowth of normal cells occurred, and a culture which elaborated both herpes and polyoma viruses (double carrier culture) was established. Elimination of polyoma virus by antibody treatment of the culture or cloning of the cells resulted in loss of resistance. The equilibrium between competing viruses and factors responsible for resistance was unstable, and three of the theoretically possible outcomes of such an equilibrium have been demonstrated: (1) the polyoma infection persisted while the herpes virus was eliminated from the culture; (2) the double carrier culture was destroyed in association with a rising titer of herpes virus; and (3) the double carrier state was maintained. Resistance of the original polyoma carrier culture and maintenance of the double carrier state appear to depend on the production of an interferon. Through the addition of exogenous interferon to susceptible, polyoma-free mouse cell cultures (3-B), the same three outcomes of herpes virus infection which had been observed in the resistant 23-P cultures could be reproduced. These results suggest that the resistance of the 23-P polyoma carrier culture to challenge with herpes virus is due to the additive effect of the interferon induced by both the polyoma and herpes infections, either of which alone is ineffective.