cssi/SciSciGPT-SciSciNet huggingface dataset:
Juggling on a high wire: Multitasking effects on performance

In this study, we develop a theoretical model that predicts an inverted-U relationship between multitasking and performance. The model is tested with a controlled experiment using a custom-developed application. Participants were randomly assigned to either a control condition, where they had to perform tasks in sequence, or an experimental condition, where they could discretionarily switch tasks by clicking on tabs. Our results show an inverted-U pattern for performance efficiency (productivity) and a decreasing line for performance effectiveness (accuracy). The results of this study indicate that the nature of the relation between multitasking and performance depends upon the metric used. If performance is measured with productivity, different multitasking levels are associated with an inverted-U curve where medium multitaskers perform significantly better than both high and low multitaskers. However, if performance is measured with accuracy of results, the relation is a downward slopping line, in which increased levels of multitasking lead to a significant loss in accuracy. Metaphorically speaking, juggling multiple tasks is much more difficult while balancing on a high wire, where performance mishaps can have serious consequences.
Cyclosporine enhances the growth of carcinogen-induced enzyme-altered foci in rat liver.

Cyclosporine, a powerful immunosuppressant, has been used successfully for organ transplantation. Its efficacy on liver transplants of patients with primary hepatic tumors remains controversial because of a high rate of recurrence of the original tumors in the transplanted livers. In this study, we experimentally tested whether cyclosporine exerts any effects on the growth of carcinogen-initiated liver cells using the short-term assays of rat liver carcinogenesis. Dietary cyclosporine, which maintained sufficient levels of blood cyclosporine and suppressed host immune functions, enhanced the development of the glutathione S-transferase, placental form-positive hepatocyte foci in the liver of male F-344 rats treated with a single weekly dose of diethylnitrosamine (75 mg/kg) for 3 wk. Dietary cyclosporine also accelerated the growth of preformed glutathione S-transferase, placental form-positive foci induced by a single dose of diethylnitrosamine (250 mg/kg) followed by the promoting regimen of a choline-deficient diet. It is possible that the enhancement of the size of hepatocyte foci by cyclosporine could be due to stimulation of growth or inhibition of regression. The mechanisms by which cyclosporine modifies the growth of preneoplastic lesions in the liver are not yet fully understood. Possible involvement of immunologically relevant cells in the liver, Kupffer cells and pit cells in the process is suggested. (HEPATOLOGY 1991;13:304–309.).
Chemotaxonomy of some Paleozoic vascular plants. Part III. Cluster configurations and their bearing on taxonomic relationships

Chemical data are given forSciadophyton, Eogaspesiea,Lepidodendropsis, Triphyllopteris, Chlidanophyton andDrepanophycus. The participation of these taxa within clustering analysis is shown to generate a cluster referable tentatively to the lycopods. Introgression of clusters representative of some major plant groups (e.g., zosterophyllophytes with the lycopods, and the trimerophytes with the progymnosperms) may reflect fortuitous statistical relationships referable to different states of preservation orbona fide phylogenetic trends. Weighting of the data is shown to result in the greater resolution of clusters, while sample size (presently 34 taxa) demonstrates a considerable effect on statistical relationships. Thermolytic alterations of extant plant materials, when incorporated within fossil plant ordination diagrams, are shown to provide internal monitors allowing for a more precise evaluation of taxonomic-chemical relationships.
Technical note: Effects of rumen passage on fluoxetine bioavailability in serum and effects of fluoxetine on serum prolactin concentration and demeanor in ewes

Sheep are becoming increasingly important in medical research. The objective of the present study was to identify changes in bioactivity of fluoxetine during ruminal passage in ewes, and to examine the effects of fluoxetine administration on demeanor and serum prolactin concentration. Twelve mature ewes were administered saline (control), daily oral fluoxetine (40 mg), or alternate-day oral fluoxetine for 10 d. Four additional ewes were fitted with rumen cannulas and administered daily fluoxetine by abomasal deposition. Serum samples were collected daily for 15 d. Serum fluoxetine concentrations (ELISA) were greater (P 0.362). However, in ewes that had received an abomasal dosage of fluoxetine, demeanor scores decreased (P < 0.029) on d 13 and 14 before returning to normal on d 15 (P = 0.397). This study indicates that mature ewes may provide a suitable model for the study of fluoxetine, but that a larger oral dosage may be required relative to the human dosage to overcome partial loss of bioactivity during ruminal passage.
Complications of Endoscopic Nasal Surgery: Occurrence and Treatment:

A consecutive series of 80 patients undergoing endoscopic nasal sinus surgery was reviewed. There were 25 complications (31%) in 19 patients in this group. Eight complications (10%) including CSF l...
Hexa‐coordinated Complexes of Nickel(II) bis(methylacetoacetate) with aromatic heterocyclic amines

Hexa-coordinated complexes of nickel(II) bis(methylacetoacetate) with pyridine, β-picoline and β-picoline have been prepared and characterised. Conductance measurements in methanol indicate non-electrolytic nature of the complexes. The complexes are all pale blue in color and are paramagnetic (μeff. = 3.0–3.1 B.M.). Electronic spectra and magnetic moment identify the complexes as octahedral ones. The d-d spectra of the complexes are discussed in the light of the structure of the complexes. The spectrophotometric data for the adducts have been used to calculate the values for the parameters, Δ, B′, β and λ.
Adenocarcinoma arising in association with gastric heterotopic pancreas: A case report and review of the literature.

We report a case of adenocarcinoma arising in a focus of heterotopic pancreas, occurring in the stomach of a 52-year-old man. The patient presented with gastric outlet obstruction. Radiographic studies revealed thickening of the gastric wall, but endoscopy failed to reveal a mucosal abnormality. A 50% distal gastrectomy was performed, along with vagotomy. Microscopic examination revealed extensive involvement of the muscularis propria of the distal stomach by heterotopic pancreas. The ectopic pancreas had a microscopic appearance consistent with Heinrich's class III, in which the majority of the heterotopic pancreas was characterized by cystically dilated duct structures. Occasional islets were present. Intimately associated with the cystically dilated ducts was a prominent number of small infiltrating ducts lined by columnar or cuboidal cells with enlarged hyperchromatic nuclei containing prominent nucleoli. These were consistent with a well-differentiated invasive adenocarcinoma. Despite multiple sectioning, no connection between the adenocarcinoma and the overlying gastric mucosa was seen. Adenocarcinoma arising within ectopic pancreas is a rare occurrence with fewer than 30 well-documented cases reported in the world literature to our knowledge. J. Surg. Oncol. 2004;87:53–57. © 2004 Wiley-Liss, Inc.
Effects of ethacrynic acid and cardiac glycosides upon a membrane adenosinetriphosphatase of renal cortex

Abstract Adenosinetriphosphatase systems have been isolated from renal cortex of several species. In guinea pig preparation, the “membrane ATPase,” or Na + -K + -Mg ++ -dependent and ouabain-sensitive component comprises 80–85% of total activity, and is highly specific as regards both substrate and inhibitors. It is inhibited only by heavy metals, cardiac glycosides and certain of the acylphenoxyacetate series of diuretics. Consistent qualitative and quantitative correlations between inhibitory activity in vitro and pharmacological activity are evident, and structure-activity relationships are discussed.
Radiographic Assessment of Hyperinflation: Correlation With Objective Chest Radiographic Measurements and Mechanical Ventilator Parameters

Background Pulmonary barotrauma is a potentially fatal complication of positive pressure ventilation. We previously found that barotrauma occurred in patients with radiographic hyperinflation, but few objective data define the relationships among hyperinflation, objective chest radiograph (CXR) measurements, ventilator parameters, and development of barotrauma. Objectives We sought (1) to assess the relationships among hyperinflation, objective CXR findings, mechanical ventilator parameters, and development of barotrauma. (2) To compare radiographic hyperinflation, ventilator parameters, and incidence of barotrauma in a current group of ICU patients with historical control subjects. Setting Medical and surgical ICU patients in a university hospital. Design Prospective blinded observational study; comparison of current series with historical control subjects. Methods One hundred two prospectively enrolled mechanically ventilated medical and surgical ICU patients each received portable supine CXRs that were reviewed independently by three radiologists who made objective measurements and subjectively determined the likelihood of hyperinflation. Ventilator parameters were recorded at the bedside at the time each CXR was obtained. CXR measurements and ventilator parameters were then related to the development of barotrauma during the course of ventilation and compared with findings of a prospective study at our institution 1 year earlier. Results Radiographically recognizable hyperinflation occurred in 18 of 102 mechanically ventilated ICU patients (18%) and correlated with lung length (24.7 vs 19.8 cm; p Conclusions Ventilation at higher Vr/kg is associated with a higher incidence of CXR hyperinflation. Radiographic hyperinflation is associated with lung length ≥24.7 cm and visualization of the sixth anterior rib. Patients with hyperinflation may be at greater risk for developing barotrauma or volutrauma. Ventilatory strategies utilizing lower volumes are associated with a lower incidence of such trauma in the current sample as compared with historical control subjects.
Workpiece dynamics during stable cutting in a turning operation

In this investigation, workpiece and cutting tool dynamics in a turning operation are investigated. It is shown that dynamic information from the workpiece propagates to the cutting tool more consistently in the tangential cutting direction than in the radial cutting direction since there is a preload that seeks to keep the tool in contact with the workpiece. Finally, trajectories in the state space comprised of workpiece accelerations parallel to the radial and tangential cutting directions were investigated and it is graphically shown that stable cutting results in more organised dynamics and unstable cutting results in less organised dynamics, which agrees with previous work.
Oxygen effects on the corrosion of niobium and tantalum by liquid lithium

The effect of oxygen on the corrosion of niobium and tantalum by liquid lithium at 600°C was studied with static capsules. An increase in the oxygen concentration of the lithium from 100 to 2000 ppm had no measurable effect on the dissolution of either refractory metal. Exposure to lithium reduced the oxygen content of niobium and tantalum to less than or equal to 20 ppm regardless of the oxygen concentration of the lithium, results that agree with thermodynamic calculations. When the initial oxygen concentration of niobium and tantalum exceeded a threshold level, lithium (with no oxygen added) penetrated the refractory metal. Penetration resulted from the formation of a ternary oxide on grain boundaries or preferred crystallographic planes and proceeded by a wedging mechanism, which is caused by stresses generated by the corrosion product. Penetration was along grain boundaries at low oxygen concentrations, the attack depth and number of affected boundaries increasing with increasing oxygen concentration. At higher oxygen concentrations, transgranular attack also occurred. The threshold oxygen concentrations for attack were 400 and 100 ppm for niobium and tantalum, respectively.
Development of a model for an air brake system with leaks and a scheme for the estimation of the steady-state pushrod stroke

Brake systems in trucks are crucial for ensuring the safety of vehicles and passengers on the roadways. Most trucks in the USA are equipped with S-cam drum brake systems and they are sensitive to maintenance. Brake deficiencies such as leaks and out-of-adjustment of the pushrod are a major cause of accidents involving trucks. Leaks in the air brake systems drastically affect braking performance by decreasing the maximum attainable braking pressure and also increasing the time required to attain the same, thereby resulting in longer stopping distances. Out-of-adjustment of the pushrod leads to loss of braking torque even if no leaks are present in the air brake system. In this paper, we present a mathematical model for an air brake system in the presence of leaks, with a view towards developing a diagnostic system for the air brake system based on the models. Additionally, we present a scheme that estimates the severity of leak in terms of the mass flow rate of air leaking from the air brake system to the ...
Adenovirus-mediated correction of the genetic defect in hepatocytes from patients with familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is an inherited deficiency of LDL receptors that has been an important model for liver-directed gene therapy. We are developing approaches for treating FH that are based on direct delivery of recombinant LDL receptor genes to liver in vivo. As a first step towards this goal, replication-defective recombinant adenoviruses were constructed which contained either thelacZ gene or the human LDL receptor cDNA expressed from a β-actin promoter. Primary cultures of hepatocytes were established from two patients with homozygous FH and one nonFH patient, and subsequently exposed to recombinant adenoviruses at MOIs ranging from 0.1 to 5. Essentially all of the cells expressed high levels of the transgene without demonstrable expression of an early or late adenoviral gene product; the level of recombinant-derived LDL receptor protein in transduced FH hepatocytes exceeded the endogenous levels by at least 20-fold. These studies support the utility of recombinant adenoviruses for efficient transduction of recombinant LDL receptor genes into human FH hepatocytes without expression of viral proteins.
Gas sensing using thermally actuated dual plate resonators and self-sustained oscillators

This paper presents an experimental investigation of the characteristics of dual plate thermal-piezoresistive MEMS resonators and self-sustained oscillators in different gases. It has been demonstrated that the natural frequency of such devices changes in different gases. Interestingly, for the same silicon structure, frequency shifts in opposite directions were observed when operated in a resonator versus a self-sustained oscillator configuration. Both thermal conductivity and density of the surrounding gas have been identified as factors affecting the operating frequency of such devices. It has been demonstrated that in resonator configuration (linear operation), the resonator frequency shift is mostly a function of gas thermal conductivity. In the oscillator configuration (nonlinear operation) however, the effect of gas density on the nonlinear stiffness of the oscillator is the dominant factor. Relatively large measured frequency shift, as high as −1340ppm in a 1:5 mixture of helium-nitrogen compared to the natural frequency in pure nitrogen, shows the potential of such devices as highly sensitive gas sensors.
Is there an increased risk of hip fracture in multiple sclerosis? Analysis of the Nationwide Inpatient Sample

BACKGROUND: Impaired ambulation, frequent falls, and prolonged immobilization combined with the high rate of vitamin D deficiency in people with multiple sclerosis (MS) could lead to an increased risk of hip fracture. METHODS: A retrospective cohort analysis of 20 years of the Nationwide Inpatient Sample (AHRQ.gov), a 20% stratified yearly sample of USA hospital admissions from the year 1988-2007, was performed. Based on International Classification of Diseases Ninth Revision (ICD9) codes, admissions with a primary diagnosis of acute hip fracture (ICD9 code 226.xx) and a secondary diagnosis of MS (ICD9 code 340) was identified. Indirect adjustment was used to compare the prevalence of MS in this population with that of the USA. Significance was set a priori at P Language: en
Computational Modeling of α/β T-Cell Receptor Loop Conformations

The T cell receptor plays a key role in the initiation of adaptive immune response by recognizing non-self peptides bound to MHC molecules. αβTCRs engage peptide-MHC through six complementarity determining region (CDR) loops, three contributed by each of the alpha and beta chains. using these CDR loops, a single TCR can scan multiple MHC molecules and can also distinguish self from non-self peptides bound in the MHC molecule. Upon engagement of a foreign MHC/peptide complex, a signaling cascade is initiated which eventually results in cytokine secretion or cytotoxicity of the target cell. Experimental data suggests that CDR loop conformations play a key role in this recognition process. Crystallographic data has suggested that CDR loops have stereotyped positions, but the conformational space of the loops is poorly understood, and in particular it is not well understood how the change in phase space of the loops contributes to the thermodynamics of peptide-MHC recognition. Here we have performed molecular dynamics simulations of the motions of bound and unbound TCR states and applied modern dimensional reduction and cluster analysis techniques to explore the number and size of CDR loop conformations. From this we have been able to explore the conformational and energetic landscape of the loop motions.
Examining the Effects of Computer Self-Efficacy and System Complexity on Technology Acceptance

Despite the prevalence of computing in all aspects of society, some computer systems may not be fully accepted by their intended users or become underutilized. Thus, acceptance and use of information technologies remain a paramount issue in information systems IS research and practice. Extending previous research by integrating computer self-efficacy and perceived system complexity as external variables to the technology acceptance model TAM, this study examines the direct and indirect effects of these two factors on system acceptance and use. The results indicated that computer self-efficacy and system complexity had significant direct effects on perceived usefulness and perceived ease of use as well as indirect effects on attitude and behavioral intention. However, the effect of perceived ease of use on attitude was stronger than that of perceived usefulness. In turn, attitude demonstrated a non-significant impact on behavioral intention. These findings highlight several implications for research and practice.
Experimental observations of overstable cellular convection

In this paper, experimental observations of the overstable cellular convection which occurs in a layer of mercury heated uniformly from below, and subject to Coriolis forces, is described. The observations confirm Chandrasekhar’s theoretical predictions regarding the wave number of the cells and of the characteristic period of the oscillatory motions. A detailed analysis of the movement of tracers clearly illustrates the periodic reversal of the convective circulation and the hexagonal pattern of the convection cells.
Are the Current Models Helpful to Understanding Staebler-Wronski Degradation?

This contribution reviews the compatibility of Staebler-Wronski models with experimental data and observations. The review will show that neither the “bond-breaking models” (originally proposed by Dersch and Stutzmann) nor the “defect conversion” models (originally proposed by Adler) can explain all observations on films and/or solar cells. It has been well accepted for some time that experimental stress and recovery phenomena, both on films and devices, always identify both “slow” and “fast” degradation and recovery mechanisms. It is argued that the quintessential understanding of the Staebler-Wronski mechanisms will come from identifying a fundamental physical process that provides a quantitative understanding of the “coupling” between the slow and fast mechanisms.
Hydrogen bonding of organic bases with trifluoroacetic acid in chloroform: A method of calculating association constants of multi-equilibria systems

13 C NMR chemical shifts of sixteen organic bases, hydrogen-bonded with trifluoroacetic acid in deuteriochloroform, are used to calculate equilibrium constants for self-association of acid and for hydrogen bonding of base with various acid n-mers. In this treatment each hydrogen bond of the species in equilibrium is assigned a free energy. The equilibrium constants then correspond to changes in these energies. Thermodynamic models are proposed which differ in the extent to which a given hydrogen bond perturbs the free energies of neighboring bonds in the molecular aggregates. Each furnishes a minimum set of independent, freely variable equilibrium constants, the values of which are then determined through a least squares fitting of the experimental data by an iterative procedure.
Theoretical and experimental approach to spectrofluorometric extractive titrations

Abstract Spectrofluorometric extractive titration (SFET) is a sensitive method for determining trace amounts of certain metals. This technique combines titration, extraction and fluorometry and is more sensitive than any of these individual techniques. A theoretical treatment is derived and is compared favorably to an experimental procedure using Ga(III) and Al(III) as metals being titrated by 8-hydroxyquinoline(oxine). A sensitivity value for the experimental SFET is derived and calculated for the Ga(III) and Al(III)-oxine systems.
The effect of heat on streptomycin and para-aminosalicylic acid in tuberculósis culture medium.

1) By chemical methods it was found that the concentrations of streptomycin in egg culture medium of 100, 500, and 1000 mcgm. per ml., only 51.8, 52.6 and 56.1 per cent respectively of the drug was recoverable after heating at 85 degrees C. for one hour. 2) PAS was found to be relatively stable to the heat of inspissation, 94.3 to 99.4 per cent being recoverable from inspissated egg medium. 3) From this study it would seem necessary to compensate for the loss of streptomycin in preparing known concentrations of the drug for assay purposes when a medium is employed which requires heat for coagulation.
Comparison of the effect of ischaemia and anoxia on the sarcolemma of the dog heart

Contraction-band necrosis, a striking morphologic lesion, is common to many types of myocardial injury including the calcium paradox and ischaemic injury with reperfusion. This lesion is characterized by explosive swelling, massive calcium overload, and severe disruption of the myofibrils due to the formation of contraction bands. The studies reviewed in this paper provide evidence that in ischaemia and reperfusion, these changes are preceded by sarcolemmal injury that occurs during the period of ischaemia. Sarcolemmal injury was evaluated by electron microscopy and by measurements of inulin diffusible space (IDS) in thin slices of myocardium incubated in vitro . Reversibly injured ischaemic myocvtes have ultra-structurally intact plasma membranes which are impermeable to inulin. Longer durations of ischaemia, sufficient to produce contraction-band necrosis during reperfusion. result in fragmentation of plasma membranes during the ischaemic intervals, and the IDS is markedly increased during subsequent incu bation. Thus ultrastructural evidence of membrane damage is present early in ischaemia and is associated temporally with the increased IDS. The role of anoxia, per s.c. in inducing membrane damage was in vestigated in tissue slices incubated at 37ΰC in crystalloidal media gassed with nitrogen. Anoxic slices produced lactate and lost ATP and adenine nucleotides, but cell volume and the IDS were not significantly increased for at least jive hours (twice the time required for severe membrane damage to develop in total ischaemia) and the plasmalemma remained intact by electron microscopy. Thus, despite depletion of high energy phosphates, membrane damage, detectable by alterations in IDS or ultrastructure, occurs much more slowly during anoxia alone than during ischaemia. These results suggest that anoxia, per Se, may not be the cause of membrane damage in ischaemia.
Different DNA Elements Can Modulate the Conformation of Thyroid Hormone Receptor Heterodimer and Its Transcriptional Activity

Abstract Thyroid-hormone receptors (TRs) form heterodimers with retinoid-X receptors (RXRs) on thyroid-hormone-response elements (TREs). However, it is not known whether the formation of liganded TR/RXR heterodimer on a TRE alone is sufficient to dictate transcriptional activity. We designed several mutated DR4s (half-sites arranged as direct repeats with a nucleotide gap of 4) that bound TR/RXR heterodimers preferentially, and employed them to characterize functional and biochemical properties of the heterodimers on DNA. Although TR/RXR heterodimer binding was similar on some of the mutated DR4s, transient transfection assays showed that TRα failed to support triiodothyronine (T3)-stimulated transcription on “inactive” DR4s but mediated basal repression on both “active” and inactive mutated DR4. T3 binding assays showed that the mutated DR4s did not affect T3 binding to the heterodimer. Finally, partial proteolysis studies revealed that binding of active DR4 elements and T3 to the heterodimer synergistically enhanced heterodimerization-induced protease resistance of TR, but not RXR, in the heterodimer. These results suggest that: 1) liganded TR/RXR heterodimer binding to a DR4 is not sufficient for transcriptional activation of the target gene, and 2) DNA sequences in specific TREs may modify T3-mediated transcription by affecting the conformation of the liganded heterodimer.
Determination of the Rate Constants of Hydrogen Absorption into Metals

Hydrogen absorption into iron (steel) membranes was studied using an electrochemical hydrogen permeation technique. The Iyer, Pickering, and Zamanzaden analysis of the measured steady-state hydrogen permeation rates, obtained for different membrane thicknesses, gives the rate constants of hydrogen absorption, k abs , and desorption, k des , in addition to those quantities which can be obtained from data for a single membrane thickness: i.e., the hydrogen surface coverage, θ H , exchange current density, i o , rate constants, k 1 and k 2 , of the hydrogen evolution reaction, and the important composite quantity called the kinetic-diffusion constant, k = k abs /(1 + k des L/D), where L is the membrane thickness and D is the diffusivity of hydrogen within the metal. The product of k and θ H determines the steady-state permeability of hydrogen within the metal. For large D and/or small L, k = k abs , and the hydrogen permeation process is under surface control. From the analysis, we obtained k abs = 2 × 10 -10 mol cm -2 s -1 and k des = 1.9 × 10 -3 cm s -1 for iron in acidic sulfate solution.
The design and operation of the upgraded BLIP facility for radionuclide research and production

Abstract The design of an extensive upgrade of BLIP and initial operating experience is described. Detailed consideration of the radiation and thermal environment, along with requirements for faster, safer target handling and better repairability, guided the engineering effort. Major improvements were made to the beam line, structural and shielding assemblies, target drive system, hot cell for target handling, and electronic control system.
923 GLUCOSE-6-PHOSPHATE DEHYDROGENASE DEFICIENCY, NEUTROPHIL DYSFUNCTION AND CHROMOBACTERIUM VIOLACEUM SEPSIS

A three year old white male with Class I glucose-6-phosphate dehydrogenase (G-6-PD) deficiency developed fever and lethargy. In spite of antibiotics, he developed septic shock and died twelve hours later. Blood and post-mortem liver cultures grew Chromobacterium violaceum. Molecular, kinetic and functional studies were carried out on erythrocytes (RBCs), leukocytes (PMNs) and fibroblasts of his identical twin and mother. Chemiluminescence was profoundly abnormal in the twin. G-6-PD isolated from the twin's fibroblasts demonstrated heat lability (27% of initial activity), normal G-6-P Km (56μM) and pH curve, and increased utilization of 2-d-G6P (76% of G-6-P rate); suggesting a new molecular variant (G-6-PD Beaumont). This is the first reported lethal infection in a child with neutrophil dysfunction due to PMN G-6-PD deficiency. This enzyme defect, like classic chronic granulomatous disease, may cause unique susceptibility to Chromobacterium violaceum.
Interannual variability of the North Polar Vortex in the lower stratosphere during the UARS Mission

Northern winters since the 1991 launch of UARS are compared to earlier years (1978 -1991) with respect to the potential for formation of Polar Stratospheric Clouds and for isolation of the north polar vortex. Daily NMC temperature minima at 465 K late in the winter of 1993-94 and again in December 1994 were the lowest values experienced during these times of the year (since 1978). Northern PV gradients were unusually strong in 1991-92 prior to late January and throughout the winter in both 1992-93 and 1994-95. Of all northern winters since 1978, 1994-95 with its early extended cold spell and persistently strong PV gradients most resembled the Antarctic winter lower stratosphere. Even so, temperatures was never as low, nor was the polar vortex as large, as during a typical southern winter. Judged by daily temperature minima and PV gradients at 465 K, meteorological conditions in the Arctic winter lower stratosphere during the UARS period were more conducive to vortex ozone loss by heterogeneous chemistry than in most previous winters since 1978-79.
DEVELOPMENT OF SHIP COURSE STABILITY DIAGRAMS FOR DEEP AND SHALLOW WATER WITH THE INFLUENCE OF TRIM

Abstract This paper represents diagrams defining the limits of ship course stability over a wide range of vessel design parameters CBB/T and L/T values. These results extend the diagram of Clarke et al. (1983) (Trans. R. Instn nav. Archit. 125, 45–68), for vessels operating at even keel in deep water, to vessels in trimmed condition operating in deep and shallow water. The diagrams show that vessel trim has a significant impact on the course stability. It is shown that trim by the stern produces an improvement in course stability while trim by the bow produces a reduction in course stability. Operating in shallow water is shown to improve the course keeping ability of the vessel.
Kernel Density Estimates of Linear Home Ranges for Stream Fishes: Advantages and Data Requirements

Abstract Kernel density estimates of linear home range can increase the information content of the home range estimate. Particularly in lotic systems, univariate kernel density estimates have desirable properties relative to simple reporting of linear ranges. Kernel density estimates are calculated from a set of relocation points (i.e., radiotelemetry contacts) that can be interpreted as a utilization distribution (UD). The UD estimates the amount of time spent at a given point within the home range. The amount of time that elapses between relocations (sampling interval), total number of relocations (sample size), and bandwidth (smoothing applied to the estimate) are important considerations when using kernel density estimates. Monte Carlo simulations using unimodal and bimodal distributions sampled randomly at sample sizes of 10-100 and three automated bandwidth selection procedures (simple normal reference, Silverman's rule of thumb, and Sheather-Jones plug-in) suggested that at sample sizes of 30 or mo...
SU‐DD‐A4‐02: Potential Improvement of PET Imaging Quantitative Accuracy with An External Reference Source

Purpose:PET has been increasingly used to assess therapeutic response. As PET suffers from many inaccuracies, it might be difficult to distinguish between actual treatment response and acquisition error. The purpose of this study was to investigate the accuracy improvement of PETimaging with an external reference source. Method and Materials: A 68 Ge reference source was scanned in two different PET/CT scanners: GE Discovery LS (DLS) and GE Discovery VCT (DVCT). The reference source was scanned at various distances from the center of bore and at a fixed position near a scatter phantom filled with 18 F . In addition, the reference source was scanned next to patients over the period of two years. A series of scans was performed for each patient. All PETimages were reconstructed using 2D‐OSEM. A cylindrical region of interest on PET was automatically segmented. Results: The measured activity was found to be inversely proportional to the distance from the center of the bore. The activity decreased by 0.95 ± 0.09 % and 0.78 ± 0.19 % per cm for DLS and DVCT respectively. The measured activity was also found to be related to activity concentration of the phantom. Within each series of patient scans, the position of the reference source varied by 1.1 ± 0.8 (SD) cm leading to 1.0 % variation in activity. However, the observed inter‐scan variation of activity was 7.0 ± 6.4 %, which cannot be explained solely by the distance effect. Conclusion: The observed inter‐scan variation for the same patients was greater than that solely due to displacement of the reference indicating a significant intra‐scan variation at different time points. The on‐going phantom studies will determine quantitative accuracy of PETimaging, providing a standardized imaging procedure.
Sulfur :limestone autotrophic denitrification processes for treatment of nitrate-contaminated water : Batch experiments

Abstract In this study, an innovative process of using sulfur:limestone autotrophic denitrification (SLAD) for treatment of nitrate-contaminated surface or wastewater was put forward. The feasibility of this SLAD process was evaluated using lab-scale batch reactors operated under both aerobic and anaerobic conditions. Autotrophic denitrification occurred in batch reactors spiked with sulfur:limestone (S:L) under either aerobic or anaerobic conditions at both high (ca. 300–500 mg NO3−–N/l) and low (ca. 30 mg NO3−–N/l) initial nitrate concentrations. Nitrate–nitrogen removal increased with the addition of granular sulfur and limestone, while the addition of a seed of autotrophic denitrifiers into the batch reactors accelerated nitrate removal. Limestone was necessary to control the pH within the reactors. The optimum sulfur:limestone ratio was 3:1 (v/v) and the extent and rate of nitrate removal depended on the alkalinity within SLAD batch reactors. Nitrate removal efficiency, sulfate production and biomass accumulation were usually higher under aerobic conditions than under anaerobic conditions. Bacterial counts signified that both autotrophic denitrificans and nondenitrifying bacteria such as Thiobacillus thiooxidans were involved in the process under aerobic conditions. The SLAD process may be a replacement for heterotrophic denitrification in pond systems such as constructed wetlands or stabilization ponds due to the fact that no organic carbon source is needed in the SLAD process and that autotrophic denitrificans exist widely in natural sediments or soil.
Effective resistance of the respiratory system studied by a quick release technique.

Abstract A human subject with mouthpiece in place makes inspiratory or expiratory effort against a closed shutter which abruptly opens when a predetermined pressure (P0) is developed. Pressure at the mouth (Pao and flow (V) are continuously recorded. When the shutter opens, Pao changes toward atmospheric — first abruptly and then gradually, while V rapidly rises to a peak value (Vpeak) and then gradually declines. In any series of trials P0 is held constant, but resistance external to the subject (Rext) is changed with each trial. In different series P0 is varied. In any series of trials at constant P0 the relationship between Pao and V was linear. The slope (K) of the straight line fitted to the experimental points was interpreted as being equal in magnitude to the ‘effective resistance’ (Reff) of the respiratory system. Reff has two components — a true resistance (Rint) and a virtual one (Rfv) related to the force-velocity characteristics of the respiratory muscles. On the assumption that Rint is independent of P0 but that Rfv varies linearly with it, Rint and Rfv can be evaluated.
Optimum choice of pulse pair spacing

A pulse pair waveform can be transmitted in order to estimate the mean of the wake velocity power spectrum at a given range sampling station of an object reentering the atmosphere. It is shown here how one may select the spacing between pulses in a pair so as to minimize the predicted variance of the mean velocity estimate. This variance is a function of the radar wavelength, the pulse signal-to-noise ratio, and the true spread of the wake power spectrum to be measured. These parameters are all assumed known a priori or available from previous data. For a given wavelength and power spectrum, the optimum pulse pair spacing to be used depends only on the signal-to-noise ratio and not on the number of pairs. Therefore, one can simply send, at the optimum spacing, the fewest pulse pairs required to achieve the necessary accuracy and thus minimize the radar energy required as well.
Breaking the habits of the heart

The authors of Habits of the Heart believe that American individualism “may have grown cancerous—that it may be destroying those social integuments that Tocqueville saw as moderating its more destructive potentialities.” However, because they come to their research with an anti‐individualistic bias in place, the authors fail to acknowledge the role of either recent historical events or influences other than individualistic ideas in shaping American culture. An alternative explanation for the emergence of the isolated self and the incoherence of moral discourse in American life is presented. Both of these phenomena are viewed as temporary responses to a shift in American character.
Neurons and networks organizing and sequencing memories

Hippocampal CA1 and CA3 neurons sampled randomly in large numbers in primate brain show conclusive examples of hierarchical encoding of task specific information. Hierarchical encoding allows multi-task utilization of the same hippocampal neural networks via distributed firing between neurons that respond to subsets, attributes or "categories" of stimulus features which can be applied in events in different contexts. In addition, such networks are uniquely adaptable to neural systems unrestricted by rigid synaptic architecture (i.e. columns, layers or "patches") which physically limits the number of possible task-specific interactions between neurons. Also hierarchical encoding is not random; it requires multiple exposures to the same types of relevant events to elevate synaptic connectivity between neurons for different stimulus features that occur in different task-dependent contexts. The large number of cells within associated hierarchical circuits in structures such as hippocampus provides efficient processing of information relevant to common memory-dependent behavioral decisions within different contextual circumstances. This article is part of a Special Issue entitled SI: Brain and Memory.
Think Phased Implementation for Successful Data Warehousing

Industry watchers have noted that the success rate of data warehouse (DW) implementations has not been exemplary. It is believed that over 50 percent of DW implementations fail to achieve their stated goals. However, there are things that executives can do to improve their chance of success. Like other forms of organizational change, the DW implementation process follows a three-phased pattern of evolution. Clear recognition by management of the phased logic of DW implementation, and the differing role of critical implementation factors (CIFs) in each of the phases, can enhance the probability of success. This article presents a framework that helps executives visualize how CIFs can be customized and embedded in each phase of the DW implementation process.
A search for4He in C60 interstitial sites

We present low temperature adsorption isotherms for4He onC60 films. Data is obtained by monitoring the frequency ofC60 coated quartz crystal microbalances versus pressure as4He gas is added to an experimental cell at constant temperature. Data for two thicknesses ofC60 (1790 A and 3200 A) taken in the range 1.5 K <T<1.7 K yield an upper limit for intercalation of4He into theC60 interstitial sites of 0.054He atoms perC60 molecule in general agreement with earlier work.
Microchimerism, Dendritic Cell Progenitors and Transplantation Tolerance

The recent discovery of multilineage donor leukocyte microchimerism in allograft recipients up to three decades after organ transplantation implies the migration and survival of donor stem cells within the host. It has been postulated that in chimeric graft recipients, reciprocal modulation of immune responsiveness between donor and recipient leukocytes may lead, eventually, to the induction of mutual immunologic nonreactivity (tolerance). A prominent donor leukocyte, both in human organ transplant recipients and in animals, has invariably been the bone marrow-derived dendritic cell (DC). These cells have been classically perceived as the most potent antigen-presenting cells but evidence also exists for their tolerogenicity. The liver, despite its comparatively heavy leukocyte content, is the whole organ that is most capable of inducing tolerance. We have observed that DC progenitors propagated from normal mouse liver in response to GM-CSF express only low levels of major histocompatibility complex (MHC) class II antigen and little or no cell surface B7 family T cell costimulatory molecules. They fail to activate resting naive allogeneic T cells. When injected into normal allogeneic recipients, these DC progenitors migrate to T-dependent areas of host lymphoid tissue, where some at least upregulate cell surface MHC class II. These donor-derived cells persist indefinitely, recapitulating the behavior pattern of donor leukocytes after the successful transplantation of all whole organs, but most dramatically after the orthotopic (replacement) engraftment of the liver. A key finding is that in mice, progeny of these donor-derived DC progenitors can be propagated ex vivo from the bone marrow and other lymphoid tissues of nonimmunosuppressed spontaneously tolerant liver allograft recipients. In humans, donor DC can also be grown from the blood of organ allograft recipients whose organ-source chimerism is augmented with donor bone marrow infusion. DC progenitors cannot, however, be propagated from the lymphoid tissue of nonimmunosuppressed cardiac-allografted mice that reject their grafts. These findings are congruent with the possibility that bidirectional leukocyte migration and donor cell chimerism play key roles in acquired transplantation tolerance. Although the cell interactions are undoubtedly complex, a discrete role can be identified for DC under well-defined experimental conditions. Bone marrow-derived DC progenitors (MHC class II+, B7-1dim, B7-2-) induce alloantigen-specific hyporesponsiveness (anergy) in naive T cells in vitro. Moreover, costimulatory molecule-deficient DC progenitors administered systemically prolong the survival of mouse heart or pancreatic islet allografts. How the regulation of donor DC phenotype and function relates to the balance between the immunogenicity and tolerogenicity of organ allografts remains to be determined.
On the difficulty of detecting density—dependent selection on polymorphic females of the damselflyIschnura graellsii: Failure to reject the null

Female colour polymorphism is a prevalent, but perplexing characteristic of many species of coenagrionid damselflies. The colour of the thorax and abdomen of an 'andromorphic' female is similar to that of the male, whereas the colour of a 'heteromorphic' female differs from that of the male. Robertson (1985) proposed that andromorphs were 'male mimics' and, thus, more likely than heteromorphs to be ignored by males as potential mates. He suggested that the benefit of avoiding time-consuming supernumerary matings balanced the cost of relatively greater predation on the purportedly more conspicuous andromorphs. Hinnekint (1987) later used 'male mimicry' as the mechanism underlying his density-dependent selection model. Hinnekint's hypothesis stated that at high male density, andromorphs were better able to avoid unnecessary matings, but at low male density, they incurred a greater risk of not mating at all. Both Robertson (1985) and Hinnekint (1987) predict that at any male density, andromorphs mate less frequently than heteromorphs. To test that prediction, Cordero (1992) quantified lifetime mating frequency and survivorship of three colour morphs of the damselfly Ischnura graellsii in two populations in Spain. Within both populations, neither the mean number of matings per female nor their mean life-span differed among the andromorphic (A) females and the two types of heteromorphic (I and O) females. Nevertheless, Cordero (1992) concluded that his data supported Hinnekint's (1987) densitydependent hypothesis. Although Codero did not quantify population density, in the population he designated as 'low density', he found that andromorphs were less likely than heteromorphs to be seen to mate at least once. In the 'high-density' population, Cordero found no difference in mating failure among morphs. But Cordero's data failed to reject the null hypothesis that female coloration makes no difference to a female's fitness. In what follows, I show that the null hypothesis appears to be the best.
Uncertainty analysis of environmental models within GIS enviroments

Abstract Information on the uncertainties in results from Geographic Information Systems (GIS) is needed for effective decision-making. Current GISs, however, do not provide this information. Uncertainties in application models used within GIS environments are a major cause of uncertainties in GIS results. To analyze model uncertainty and its propagation, model sensitivity analysis is first performed. This paper discusses techniques for model sensitivity analysis, model uncertainty analysis, and analysis of the propagation of model uncertainty, within the context of environmental models used within GIS. A two-dimensional air quality model, based on the first-order Taylor method, is used to demonstrate these techniques.
Plasma-sprayed alloys considered for an advanced concept for a gas turbine bucket

Abstract In this study, the metallurgical aspects of several alloy systems prepared by low pressure plasma spraying were evaluated. Highly dense thick layers (greater than 6 × 10 -2 cm) of Inconel 617, Inconel 671, MZC copper, Cu-5Ni-2.5Ti and Cu-2Ni-1.2Ti were deposited onto Inconel 718 and OFHC copper substrates. These coating layers were shown to be tenaciously bonded to the substrates provided that proper processing controls were used.
Rates of Convergence for Double Sequences

In 1900 Pringsheim presented the following definition for convergence of a double sequence (i.e. ordinary infinite matrices). A double sequence [x] has limit L if the terms of the double sequence approaches L as both the column and row indices increases. Using this notion for convergence I will present definitions for asymptotically equivalent double sequences, rate preserving four dimensional matrix transformation, and these definitions shall be used to present two natural invariance theorems.