cssi/SciSciGPT-SciSciNet huggingface dataset:
Thermodynamic optimization of finned crossflow heat exchangers for aircraft environmental control systems

Abstract This paper shows that the main geometric features of a flow component can be deduced from the thermodynamic optimization of the global performance of the largest flow system that incorporates the component. This approach represents a departure from the usual approach, where a flow component is optimized in isolation. The example chosen is the counterflow heat exchanger of the environmental control system (ECS) used on modern aircraft. The heat exchanger is fitted with a diffuser and a nozzle for the ram air, and the ECS runs on the boot strap air cycle, employing an additional compressor and turbine. Two heat transfer surface types are considered, finned and smooth parallel plates. Numerical results are reported for the external geometric aspect ratios of the heat exchanger, and for the plate-to-plate spacing of the smooth-plates model. It is shown that the optimized geometry for the core with finned surfaces is nearly the same as the optimized geometry for the core with smooth plates. Several of the optimized geometric features are robust with respect to changes in external parameters that vary from one application to the next. The method illustrated in this paper – the thermodynamic (constructal) optimization of flow geometry – is applicable to any system that runs on the basis of a limited amount of fuel (exergy) installed onboard, e.g., automobiles, ships, portable tools.
In situ deposition and XPS characterization of lithium based solid glass electrolyte/vanadia interfaces : observation of lithium migration

Abstract In situ X-ray Photoelectron Spectroscopy (XPS) was used to examine the interfaces formed by reactive sputter deposition of vanadia onto several lithium based solid glass electrolytes. It has been found that lithium migration to the vanadia/vacuum interface can occur during deposition and that the presence of lithium can influence the oxygen uptake during the reactive sputtering process. The lithium migration is driven by an electric field present due to the plasma; it is shown that the migration can be influenced by the deposition conditions.
A simplified method for the measurement of nonmetabolized 2-[18F]F-A-85380 in blood plasma using solid-phase extraction.

Abstract Quantification of α 4 β 2 * nicotinic acetylcholine receptors using 2-[ 18 F]fluoro-3-(2( S )-azetidinylmethoxy)pyridine (2-[ 18 F]FA) and positron emission tomography (PET) imaging requires measurement of nonmetabolized radioligand in blood plasma, which was previously accomplished using high-performance liquid chromatography (HPLC). Here, we introduce a one-step solid-phase extraction (SPE) method for measuring the concentration of nonmetabolized 2-[ 18 F]FA. This method allows many samples to be processed in a short period of time. SPE effectively separated 2-[ 18 F]FA from radioactive metabolites typically observed in blood plasma after administration of radioligand in humans. Measurements of the 2-[ 18 F]FA parent fraction in healthy human volunteers obtained using the SPE method were nearly identical to those obtained using HPLC (1.3±5% average underestimation of SPE), and reproducibility was good within and between runs (2% and 6% coefficient of variation, respectively). SPE recovery of 2-[ 18 F]FA from blood plasma was not appreciably diminished (3±0.6%) by a larger volume of blood plasma loaded onto the cartridge, suggesting the possibility of increasing the plasma sample volume at later times in a PET study to improve measurement sensitivity. 2-[ 18 F]FA was stable in blood stored on ice over 8 h and in saline at low concentrations ( 18 F]FA in healthy human volunteers were estimated as 4.2±0.8 h and 220±70 L, respectively. These results suggest that SPE is the method of choice for the determination of the plasma 2-[ 18 F]FA concentration when measurement of individual metabolites is not required.
Structure and Action of Nemertine Toxins

Bacq (1936, 1937) discovered two substances by pharmacological experiments using whole body extracts of various nemertine species. “Amphiporine,” found only in hoplonemertines, stimulated nicotinic acetylcholine receptor-mediated events. “Nemertine” evoked spontaneous action potentials in isolated crab nerves. Both substances caused convulsions when injected into crabs. Anabaseine, a pyridine alkaloid isolated from the hoplonemertine Paranemertes peregrina , has chemical and pharmacological properties equivalent to “amphiporine.” Hoplonemertines produce a wide variety of pyridine toxins depending on the species. The heteronemertine Cerebratulus lacteus contains cytolytic (10,000 dalton) and neurotoxic (6,000 dalton) proteins. The neurotoxic polypeptides most closely resemble “nemertine”: they cause repetitive spiking in isolated crustacean axons. Several cytolytic and neurotoxic “isotoxins” occur within Cerebratulus . Both the hoplonemertine and heteronemertine toxins are localized in the integumentary tissues of the body wall and proboscis. So far, the pyridine alkaloid toxins are only found in the Enoplan species, where they probably function as both offensive and defensive toxins. Protein toxins have only been found in Anoplan species; they probably serve as a chemical defense against some predators.
Continuous Corn Response to Residue Management and Nitrogen Fertilization

Harvesting corn (Zea mays L.) residue in continuous corn (CC) may require changes in crop management for increased efficiency. Experiments were conducted in Illinois to determine how residue removal and tillage affect surface residue after planting and the response ofCC to N fertilization. Partial removal of residue left 21 to 26% surface residue coverage with a chisel plow system, compared with 53 to 65% with no-till. Across 2 yr with 92 to 128 mm rainfall during June and July, grain yield only responded to N fertilization with no-till. When compared with full removal of residue in no-till, no removal increased the economically optimum N fertilizer rate (EONR) by 58% and yield at the EONR from 8.6 to 10.3 Mg ha -1 . Across five environments with 201 to 264 mm rainfall during June and July, yields with full removal of residue were 13.1 Mg ha -1 with no-till and 13.4 Mg ha -1 with tillage. With partial and no residue removal, yields were 5 and 12% greater with the chisel plow than with the no-tillage system, respectively. Across tillage systems in these environments, retaining all residue increased the EONR by 13% and decreased yield at the EONR by 4% when compared to full or partial removal of residue. On productive soils with adequate rainfall, removal of residue has the potential to raise yields and to lower N fertilizer requirements in the short term. This advantage, however, needs to be balanced against the need to retain adequate soil cover to maintain soil productivity.
Microorganisms and calcium oxalate stone disease

Microorganisms may have a role in the pathogenesis and prevention of kidney stones. The subjects of this review include nanobacteria, Oxalobacter formigenes, and lactic acid bacteria. Not reviewed here is the well-described role of infections of the urinary tract with Proteus species and other urease-producing organisms associated with struvite stone formation. Nanobacteria have been proposed to be very small (0.08-0.5 nm), ubiquitous organisms that could play a role in stone formation. The theory is that nanobacteria can nucleate carbonate apatite on their surfaces and thereby provide the nidus for stone formation. However, their existence remains uncertain and many investigators are openly skeptical. Recent investigations suggest that they are artifacts, and not actually living organisms, but their proponents continue to study them. O. formigenes is an obligate anaerobe which may be important in the prevention of stone formation. Its sole substrate for generation of ATP is oxalate. It may thereby metabolize its human host's dietary oxalate and diminish intestinal absorption and subsequent urinary excretion of oxalate. There is evidence that the organism's absence, perhaps sometimes due to courses of antibiotics, may be a cause of hyperoxaluria and stone formation. In early investigations, patients not colonized with the organism can be recolonized. Urinary oxalate can be diminished by accompanying an oxalate-containing meal with the organism. One study demonstrated that a preparation of lactic acid bacteria successfully reduced urinary oxalate excretion in 6 patients with calcium oxalate stones and hyperoxaluria. The mechanism of this effect is uncertain since these bacteria lacked the gene possessed by O. formigenes which codes for that organism's oxalate uptake mechanism. The author is currently completing a small randomized controlled clinical trial with this preparation in calcium stone-forming patients with idiopathic hyperoxaluria.
Microhydrodynamic analysis of nanogrinding in stirred media mills

The dynamics of the milling media in a turbulent flow is considered. The mean velocity of the milling beads is calculated on the assumption that the power spent on stirring is transferred into the energy of turbulent eddies. The energy spent on stirring dissipates as a result of media–liquid viscous friction, lubrication, and by inelastic collisions of the beads with each other. The maximum force at which the milling beads can compress particles between them is calculated by the Hertzian theory of elastic impact. The frequency of compressions for a single particle is evaluated by probabilistic analysis. A criterion of milling efficiency, based on calculating the energy spent on the plastic particle deformation, is proposed. A numerical study of the milling bead dynamics and their interactions with the particles in the mixing tank is performed. The numerical results are in qualitative agreement with the experimental data. Both the numerical and experimental analyses show that, from the perspective of hydrodynamics, an optimization of stirred media mills can be achieved by choosing the optimum size and concentration of the milling media. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Financial Abuse in Elderly Korean Immigrants: Mixed Analysis of the Role of Culture on Perception and Help-Seeking Intention

This study aims to evaluate how elderly Korean immigrants perceive and respond to a hypothetical incident of financial abuse on the basis of their cultural background. By using a quota sampling strategy, 124 elderly Korean immigrants were recruited. A mixed-method approach was employed to explore the role of culture on elderly immigrants' view of financial abuse and the construct of independent and interdependent self-construal was adopted to theoretically guide the study. Mixed-method analysis confirmed considerable influence of culture, particularly in responding to the abusive situation. Although the vast majority of the elders (92%) perceived financial abuse as elder mistreatment, only two-thirds (64%) intended to seek help. Five major themes for not seeking help were produced. These are: (a) issues related to family problems, (b) tolerance of the abuse, (c) shame, (d) victim blame, and (e) mistrust toward third party intervention. A series of binary logistic regressions revealed (a) a lower likelihoo...
A Method for Detecting Positive Growth Autocorrelation without Marking Individuals

In most ecological studies, within-group variation is a nuisance that obscures patterns of interest and reduces statistical power. However, patterns of within-group variability often contain information about ecological processes. In particular, such patterns can be used to detect positive growth autocorrelation (consistent variation in growth rates among individuals in a cohort across time), even in samples of unmarked individuals. Previous methods for detecting autocorrelated growth required data from marked individuals. We propose a method that requires only estimates of within-cohort variance through time, using maximum likelihood methods to obtain point estimates and confidence intervals of the correlation parameter. We test our method on simulated data sets and determine the loss in statistical power due to the inability to identify individuals. We show how to accommodate nonlinear growth trajectories and test the effects of size-dependent mortality on our method's accuracy. The method can detect significant growth autocorrelation at moderate levels of autocorrelation with moderate-sized cohorts (for example, statistical power of 80% to detect growth autocorrelation ρ (2) = 0.5 in a cohort of 100 individuals measured on 16 occasions). We present a case study of growth in the red-eyed tree frog. Better quantification of the processes driving size variation will help ecologists improve predictions of population dynamics. This work will help researchers to detect growth autocorrelation in cases where marking is logistically infeasible or causes unacceptable decreases in the fitness of marked individuals.
Performance of self-reported measures for periodontitis in rheumatoid arthritis and osteoarthritis

Background: This study evaluates the performance of self-report against the reference standard of clinically defined periodontitis in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) after accounting for factors associated with periodontitis.Methods: Six self-report periodontitis questions were evaluated in patients with RA and OA. Questions were validated against a reference standard of severe and moderate-to-severe periodontitis based on full-mouth examination. Multivariable logistic regression was used to evaluate the performance of: 1) self-report alone; 2) age, sex, education, and smoking status; and 3) a combination of the above. Model performance was assessed using the c-statistic. Convergent validity of self-reported “bone loss/deep pockets” and “loose teeth” was assessed; associations of self-report with RA disease characteristics were explored.Results: Self-report performed similarly in RA and OA, with individual question specificity for periodontitis ≥68% and sensitivity from 9.8...
General applications 2: decision making of embedded I/O buffer sizes using the queueing simulation model for a shared-memory system

This paper presents a methodology of decision-making for embedded I/O buffer sizes in a single-bus shared-memory system. The decision is made with the aid of a queuing model, simulation, and the proposed algorithm. The generalized queueing model is simulated to cover two cases: independent processing units and pipelined processing units in a shared-memory environment. The objective is to obtain the best performance with the optimized embedded buffers in the system. Therefore, an algorithm is developed to find the optimal solution efficiently by exploring the correlation between buffers and system performance. The local optimum is guaranteed. The method can be widely applied to many applications.
An Efficient Route to Well-Defined Macrocyclic Polymers via “Click” Cyclization

Polystyrene macrocycles have been prepared from ATRP precursors by modification of the terminal bromide to an azide, followed by “click” cyclization with a pendant alkyne from the initiator. This route offers exceptional control over the size and polydispersity of the macrocyclic polymers, as well as providing tolerance to a number of functional groups.
An examination of entrepreneurship education in the United States

Purpose – This paper seeks to provide an analytical overview of the current state of entrepreneurship education in the USA for the years 2004‐2005.Design/methodology/approach – The author performed an extensive review of the literature in entrepreneurship education and enhanced the review by conducting a national survey of two and four‐year colleges and universities. This survey was the sixth since 1979 conducted by the author to examine trends and the “current state of entrepreneurship education.”Findings – The 2004‐2005 survey indicates that the trends, especially in the use of technology initially examined in prior national studies of entrepreneurship, have continued in a similar direction and in some areas, for example, the use of technology has increased dramatically. Also, new findings confirm that the traditional teaching method of requiring students to create a business plan is still used and is popular. Finally, the data show that entrepreneurship educators are increasingly using guest speakers a...
Enhancing wireless internet performance

This article surveys wireless Internet technologies whose goals are to enhance networking performance. These technologies are organized into seven categories: power saving, mobile performance, Multimedia Quality-of-Service, application performance, transport-layer characteristics, data-link layer, and non-TCP options. For each category, the main technical characteristics are outlined, the architectural aspects are discussed, and the advantages and disadvantages are analyzed. The objective of this article is to contribute to the overall understanding of the technologies available for constructing the forthcoming wireless Internet infrastructure.
Evidence for an Elemental Sulfur Component of the Clouds from Venus Spectrophotometry

The decrease in the reflectivity of Venus in the near-UV can be explained if the clouds contain particles of elemental sulfur in addition to sulfuric acid. The low-resolution McDonald-Pittsburgh spectrum can be fitted by two sulfur-containing, multiple-scattering cloud models: (1) a mixed cloud consisting of one particle of elemental sulfur of radius 10 microns for every 670 particles of sulfuric acid of radius 1 micron, and (2) a layered cloud of optical thickness tau = 1.0 consisting of one-micron particles of sulfuric acid overlying a thick cloud of elemental sulfur particles of radius 3.6 microns. Some of the sulfur is incompletely polymerized. The source of the sulfur is photo-dissociation of COS, although some may also be recycled from the lower atmosphere. The sulfur plays a crucial role in the planetary meteorology of Venus since it is responsible for the bulk of the absorption of solar energy.
Multistep solution-mediated formation of AuCuSn2: mechanistic insights for the guided design of intermetallic solid-state materials and complex multimetal nanocrystals.

Understanding how solids form is a challenging task, and few strategies allow for the elucidation of reaction pathways that are useful for designing new solids. Here, we describe an unusual multistep reaction pathway that leads to the formation of AuCuSn2, a new ternary intermetallic compound that was discovered as nanocrystals using a low-temperature solution route. The formation of AuCuSn2 using a modified polyol process occurs through a multistep pathway that was elucidated by taking aliquots throughout the course of the reaction and studying the products using a variety of techniques. The reaction proceeds through four distinct steps: (a) formation of Au nanoparticles at or near room temperature, mediated by a galvanic reaction between Au3+ and Sn2+ (forming Au0 and Sn4+, precipitated as SnO2 that forms a shell around the nanoparticles), (b) formation of NiAs-type AuSn nanoparticles, along with Cu and Sn, upon addition of NaBH4, (c) aggregation and thermal interdiffusion to form AuCuxSny alloy nanopa...
VICTORIA: VMX indirect compute technology oriented towards in-line acceleration

There is increasing interest in the use of accelerators in computer systems. Accelerators are processor-attached hardware units that can perform certain functions faster than the conventional general purpose processor. In this paper, we describe the VICTORIA PowerPC architecture, which is based on the iVMX accelerator technology. The iVMX accelerator extends the existing VMX architecture with indirect register addressing. That approach greatly extends the architected space of registers and opens the door for highly optimized vector algorithms that can sustain very high processing rates. The large space of registers is directly controlled by the executing code and offers a sufficiently large storage to hold sizeable intermediate results. This helps reduce the negative effects of limited memory bandwidth and high memory latency. The iVMX accelerator is an example of in-line accelerator; that is, the instructions that drive the accelerator are part of the same stream that drives the main processor. Compared to off-line accelerators, which execute their own instruction stream, in-line accelerators present a much more convenient programming model.
Implanted functional neuromuscular stimulation systems for individuals with cervical spinal cord injuries : Clinical case reports

Abstract Objective: To determine the feasibility of providing the ability to stand and to facilitate the performance of standing transfers to individuals with cervical-level spinal cord injuries via functional neuromuscular stimulation (FNS). The applicability of implantable technology to this population was investigated, and the characteristics of the potential system users were explored. The effects of FNS on the effort and assistance required to stand and complete standing transfers were examined. Setting: Institutional rehabilitation practice. Design: Nonrandomized controlled trial. Patients: Twenty-four individuals with low cervical spinal cord injuries were evaluated for inclusion in a program of lower extremity FNS, four of whom received the intervention. Intervention: Chronically indwelling percutaneous intramuscular electrodes were used to exercise the hip, knee, and trunk extensors and develop activation patterns to produce standing function. These temporary systems were then replaced with silicone-enclosed helical wire electrodes suitable for eventual use with an eight-channel implantable receiver/stimulator. Main Outcome Measures: Full sensory and motor evaluations were performed and physical contraindications to stimulation were catalogued. For active subjects, American Spinal Injury Association Total Motor Scores with and without FNS were recorded, along with quadriceps strength and ability to complete exercise, standing, controlled sitting, and standing transfer maneuvers. Performances of implanted electrodes were determined by the stability of recruitment properties, impedances or surface potentials, and serial radiographs. Results: Motor scores increased an average of nine points with stimulation over baseline volitional values. With FNS, all four volunteers were able to exercise, stand, and sit independently or with minimal assistance. Although they required varying degrees of assistance with the pivot phase of the transfer maneuver, all were able to raise and lower their body weight independently with stimulation and to use the system to facilitate standing transfers. One participant received the implantable receiver/stimulator, which remains operational at follow-up more than 3 years later. Conclusion: FNS can provide the ability to exercise, stand, and transfer to individuals with tetraplegia, even in the presence of medical complications and upper extremity impairment. FNS facilitates standing transfers by eliminating the heavy lifting usually required by a caregiver, thus decreasing the effort and assistance necessary to gain access to places impossible to approach with conventional sliding transfers.
The effect of toxin from Leiurus quinquestriatus scorpion venom on the polymerization and stability of microtubules

The venom of the scorpion Leiurus quinquestriatus, well-known for its actions on voltage-sensitive sodium channels, has now been shown to have pronounced effects on the in vitro polymerization and stability of neuronal microtubules purified by temperature-dependent cycles of assembly and disassembly. The crude venom, at concentrations as low as 100 micrograms/ml, alters both the extent of tubulin polymerization, as monitored by turbidity, and the appearance of polymerized material under electron microscopic examination. Structures formed in the presence of the venom retain the temperature sensitivity characteristic of normal microtubules, but respond to calcium ions abnormally with a dispersal of ordered structures, as reflected by both increased light scattering and electron microscopic analysis. Fractionation of the crude venom suggested that the active component was the same as the polypeptide neurotoxin which interacts with voltage-sensitive sodium channels and this identity was subsequently verified. Thus, the effect on microtubules of highly purified L. quinquestriatus sodium channel toxin obtained from an independent source was indistinguishable from that of the crude venom. These results indicate that the sodium channel toxin from L. quinquestriatus is also a potent cytoskeletal agent in vitro. This finding may be related to the growing body of evidence suggesting that the neuronal cytoskeleton plays a functional role in the maintenance of membrane excitability.
Theoretical investigation of cis-nitric oxide dimer with hybrid density functional theory methods

Hybrid density functional theory (DFT) has been applied to a model geometry and derived bonding energy of cis-nitric oxide dimer. The obtained results were compared with ab initio RHF and MP2, SVWN and BLYP DFT and experimental data. The basis sets used ranged from small (3-21G*) to large (6–311 + + G(3df)). The suitability of DFT hybrid methods for modeling this system is discussed.
PRESENILIN-NULL CELLS HAVE ALTERED TWO-PORE CALCIUM CHANNEL EXPRESSION AND LYSOSOMAL CALCIUM; IMPLICATIONS FOR LYSOSOMAL FUNCTION

Presenilins are necessary for calcium homeostasis and also for efficient proteolysis through the autophagy/lysosome system. Presenilin regulates both endoplasmic reticulum calcium stores and autophagic proteolysis in a γ-secretase independent fashion. The endo-lysosome system can also act as a calcium store, with calcium efflux channels being recently identified as two-pore channels 1 and 2. Here we investigated lysosomal calcium content and the channels that mediate calcium release from these acidic stores in presenilin knockout cells. We report that presenilin loss leads to a lower total lysosomal calcium store despite the buildup of lysosomes found in these cells. Additionally, we find alterations in two-pore calcium channel protein expression, with loss of presenilin preventing the formation of a high molecular weight species of TPC1 and TPC2. Finally, we find that treatments that disturb lysosomal calcium release lead to a reduction in autophagy function yet lysosomal inhibitors do not alter two-pore calcium channel expression. These data indicate that alterations in lysosomal calcium in the absence of presenilins might be leading to disruptions in autophagy.
Singularity Avoidance for the 3-RRR Mechanism Using Kinematic Redundancy

Based on its simple structure, base-fixed actuators, high payload capacity, high accuracy, and high mechanical rigidity, the 3-RlowbarRR mechanism is a valuable planar parallel manipulator. However, the 3-RlowbarRR mechanism is known to have singular loci within its workspace affecting its use. In this paper, singularity avoidance of the 3-RlowbarRR mechanism using kinematic redundancy is presented. First, singularity analysis of the proposed 3-RlowbarPlowbarRR mechanism is described and a simple and effective redundancy resolution algorithm based on local optimization suitable for real-time control is developed. Here, the cost function in the optimization is designed to avoid the most problematic singularity configurations, where the end-effector can be locally moved even though all actuated joints are locked. Results from simulation show that the resultant 3-RlowbarPlowbarRR mechanism can be used to avoid singularities associated with the 3-RlowbarRR mechanism, and enlarges the usable workspace.
The J.H.B. archive report: the Alexander Forbes papers.

Alexander Forbes (1882-1965), Professor of Physiology at Harvard Medical School, was an American pioneer in the electrical study of the nervous system. The Alexander Forbes Archive comprises the professional papers and materials generated by him during sixty years of research, and reflects an exciting period of controversy and discovery in neurophysiology. Forbes was a student, collaborator, and close friend of some of the most brilliant members of several generations of British and American physiologists, including Charles S. Sherrington, Keith Lucas, E. D. Adrian, A. V. Hill, John C. Eccles, Walter B. Cannon, Hallowell Davis, Stanley Cobb, and George Wald. His personal background was equally noteworthy: he was of a wealthy and distinguished Massachusetts family, son of the president of Bell Telephone Company and grandson of Ralph Waldo Emerson.' Forbes's many contributions stemmed from his extraordinary ability to obtain and utilize quantitative recordings of electrical events in the nervous system. His interpretation of such data led to a greater understanding of the complex neurological interactions which are manifested as an integrated perception or response.2 Improvements in physiological recording techniques were among the most important advances attributable to Forbes. In 1914-1915, using a string gplvanometer, he made the first electrical recordings of central reflex phenomena.3 In 1919-1920,
How the Truth and Reconciliation Commission Challenges the Ways We Use History

(2002). How the Truth and Reconciliation Commission Challenges the Ways We Use History. South African Historical Journal: Vol. 47, No. 1, pp. 162-190.
Transient Kinetic and Dynamic Interactions between Verapamil and Dofetilide, a Class III Antiarrhythmic

Potential kinetic and dynamic interactions between the new class III antiarrhythmic dofetilide (D) and the calcium channel blocker verapamil (V) were determined in 12 young healthy male volunteers. A fixed sequence of V80 mg tid, placebo, D 0.5 mg bid, and D + V was given as matching active and placebo capsules. In steady-state conditions during combination treatment, a modest increase in mean (+/- SD) peak plasma concentration of dofetilide from 2.40 +/- 0.42 to 3.43 +/- 0.71 ng x ml(-1) (43% increase, p < 0.1) was noted. During the combination period, for the first 4 hours, mean AUC values for D increased from 7.4 +/- 1.0 (D alone) to 9.2 +/- 1.4 ng x h x ml(-1) (26% increase, p <0.1). No other significant pharmacokinetic interaction was seen. These transient changes were concurrent with trends for a dynamic interaction. The maximal mean increase in QT, over steady-state baseline values was 20 msec for D alone versus 26 msec during combination therapy. This relatively small interactive effect occurred only while peak plasma drug concentrations were developing at 1 to 3 hours after dosing and is probably caused by the known effect of verapamil to increase hepatic and portal bloodflow. In view of this interaction and the relationship between dofetilide plasma concentration and torsade, verapamil is contraindicated in patients receiving dofetilide.
Iron availability – the implications of short‐term regulation

Summary The availability of iron depends on a number of dietary and physiological variables, and it is the sum of all these factors that ultimately determines iron status of the body. Iron homeostasis is almost certainly regulated by intestinal absorption via the mucosal cells, the mechanism of which is not yet fully understood. However, studies in animals and man have clearly shown that absorption is influenced by iron status, since the capacity for absorption is enhanced in iron-deficiency (long-term regulation), and also by the amount of iron ingested during the days preceding an absorption test (short-term regulation). Evidence exists to support the hypothesis that the latter regulation is dependent on local effects of iron in the lumen of the intestine; it may well be the feedback mechanism whereby iron homeostasis is maintained in the presence of constantly fluctuating levels of iron. In iron absorption studies, it is important that this short-term regulation is taken into account in terms of adequate dietary control of experimental subjects.
Protein synthesis in lymph nodes during the development of contact sensitivity in the guinea-pig.

Abstract 3rotein synthesis in lymph nodes of non-sensitized guinea-pigs and of guinea-pigs sensitized 4 and 6 days previously to the chemical agent ‘oxazolone’ was studied by in vitro incorporation of 14 C-leudine. Analysis of extracts of these lymph nodes by DEAE-cellulose chromatography and autoradio-immunoelectrophoresis showed that there was a marked increase in 14 C-leudine incorporation by lymph nodes on the fourth day after sensitization and a subsequent reduction by the sixth day. Correlated with this, there was a significant increase in synthesis of γ 2 -globulin by 4-day sensitized lymph nodes which were also synthesizing a number of other proteins, at least 3 of which migrated electrophoretically in the α-globulin region. Radioactive peaks from DEAE-cellulose chromatography of extracts of 4-day sensitized lymph nodes were sub-fractionated by Sephadex G-200 gel-filtration. This revealed a number of newly-synthesized components which were not detectable by immunoelectrophoresis. The increased synthesis of proteins at 4 days after sensitization coincides with the presence in the lymph node of maximum numbers of immunoblasts, and the possible significance of this is discussed.
THE POETRY, PROPHECY, AND POWER OF LIFE'S SACRED TEXTS

The focus of this article is that contemporary memoirs are sacred texts brimming with poetry, prophecy, and power. These memoirs share the dynamics found in the section of the Hebrew Scriptures known as The Writings, also known as the Wisdom Tradition in the Christian Scriptures. Contemporary memoir is more than theological expression; it is theology itself.
Imaging features of breast malignancy: breast ultrasound and MR imaging correlation

Recent advances in breast imaging, including volumetric breast ultrasound and breast magnetic resonance (MR) imaging, now provide multiplanar capability for detailed morphologic assessment of breast malignancies. This article describes the imaging findings of common breast cancers, utilizing volumetric breast ultrasound with MR imaging correlation. Knowledge of the characteristic appearances of breast malignancy can facilitate the diagnosis and management of breast masses, particularly when obscured by excessive breast density on mammography examinations.
Letter by Sen and Powers Regarding Article, “Adherence to Third European Cooperative Acute Stroke Study 3- to 4.5-Hour Exclusions and Association With Outcome: Data From Get With The Guidelines-Stroke”

We read with interest the article by Cronin et al1 concerning “Adherence to third European cooperative acute stroke study 3- to 4.5-hour exclusions and association with outcome: data from get with the guidelines-stroke.” The study compares outcomes between patients treated with intravenous tissue-type plasminogen activator (tPA) 0 to 3 hours and 3 to 4.5 hours. The authors conclude that patients with European Cooperative Acute Stroke Study (ECASS III)–specific exclusion criteria for the 3- to 4.5-hour window are frequently treated with tPA and the presence of the additional exclusion criteria was not associated with worse outcomes in the 3- to …
Methylation studies on amylose polyalcohol

Abstract Amylose (corn and potato) was subjected to prolonged periodate oxidation, and the resulting polyaldehyde was reduced with sodium borohydride to the corresponding polyalcohol. Methylation of the amylose polyalcohol, followed by methanolysis, gave 1,4-di- O -methylerythritol and a small proportion of 1- O -methyl- D -erythritol. These findings support the view that amylose from both sources is slightly branched by (1→6)- D -glucosidic linkages.
A complex wave synthesizer

THE USE OF Fourier's method for analysis of complex waves, whether they be electric, mechanical, or aural in nature, is well known. A device which could produce a variety of complex waves could be used to check tedious computations or even to apply a desired complex wave to a system in order to observe its response. Such a device is the subject of this article.
The narrative productions of children who stutter: A preliminary view

Abstract The narrative abilities of 16 children, half of whom had been diagnosed as stutterers, were compared in two tasks. One of these tasks involved story retelling, where the children were twice asked to retell the same story that had been conveyed to them in a 6-minute videotype, once to a naive listener and once to a listener who had already heard the story. The children were also asked to complete three original stories after being provided with the first sentence of each story. Analyses of the length and complexity of the stories and their constituent episode structures revealed some nonsignificant differences between the narratives produced by the normally fluent subjects and those diagnosed as stutterers. Most of the stutterers produced stories that were shorter and had fewer completed episodes than those produced by their age- and gender-matched peers. One significant difference was the nonstutterers' longer and more elaborate story retellings with listeners who were unfamiliar with the story. The importance of deriving discourse level information as part of the information gleaned in the speech and language assessments of young children who stutter is supported. Also supported is the notion that where the narrative competencies of young children who stutter are concerned, production information may not be sufficient for an accurate assessment.
Stiffness and inelastic deformation in acrylic-titanium composite implant materials under compression

A variety of acrylic bone cement-metal composite materials were prepared and tested in simple compression at 37 degrees C in order to evaluate the mechanical behavior of these materials for possible use in bone replacement. The stiffness of the composite was of particular concern, and a simple rule of mixture was used to raise the modulus of acrylic bone cement. The reinforcement of the cement was accomplished by titanium and Ti-6Al-4V in different forms, e.g., wire, sheet, wire mesh, and powder. Test results demonstrated that the stiffness of the bone cement could indeed be increased by a desired amount to that of bone. A 16% volume fraction consisting of 25 0.10 cm diam Ti-6Al-4V wires increased the modulus of the bone cement by 380% to a value comparable to the modulus of cortical bone. Titanium sheet was nearly as effective as wires in increasing the modulus of bone cement, while titanium mesh was not a significantly effective reinforcing material. The amount of titanium powder added to the bone cement did not alter the compliance of the matrix material. In addition, as the flow strength increased, the strain to the point of load instability decreased. It was concluded that the extent of stiffening was governed by nonuniform deformation in the metal and the adjacent matrix which could be explained on the basis of geometrical considerations. Some of the limitations of the test results as well as methods of predicting the composite implant material behavior are also outlined.
Operational Definitions and Learning Disabilities: An Overview:

In 1981, the National Joint Committee for Learning Disabilities (NJCLD) adopted the following definition: Learning disabilities is a generic term that refers to a heterogeneous group of disorders manifested by significant difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning, or mathematical abilities. These disorders are intrinsic to the individual and are presumed to be due to central nervous system dysfunction. Even though a learning disability may occur concomitantly with other handicapping conditions (e.g., sensory impairment, mental retardation, social, or emotional disturbance) or environmental influences (e.g., cultural differences, insufficient/inappropriate instruction, psychogenic factors), it is not the direct result of these conditions or influences. (Hammill, Leigh, McNutt, & Larsen, 1981, p. 336) This definition has been evaluated positively compared to others (e.g., Interagency Committee on Learning Disabilities, 1987; U.S.O.E., 1977; e.g., see Hammill, 1990; Silver, 1988). However, it is not an operational definition, because it does not specify the operations or procedures by which the construct of learning disabilities can be recognized and measured. For example, it is unlikely that current studies on learning disabilities would be published in refereed research journals if their subject sample description relied solely on the NJCLD definition. Therefore, if we are to enhance our understanding of learning disabilities, serious consideration must be given to the selection of parameters that go into an operational definition. It is in this spirit that this special issue of the Learning Disability Quarterly was developed. In this opening discussion, I seek to distill some ideas that unify what otherwise might appear to be a collection of unintegrated articles. The reader should remember, however, that each article is written from the authors' own research perspective. I deliberately solicited articles of diverse research perspectives to allow a number of issues to be considered. For example, in the first article Kavale, Forness, and Lorsbach discuss the limitations of operational definitions, whereas the article by Stanovich focuses on the irrelevancy of IQ. Likewise, Hynd, Marshall, and Gonzalez emphasize the relevance of studies originating from neuropsychology, Reynolds' article targets psychometric models, while Bryan considers primarily social cognition. No doubt, to integrate these diverse perspectives will be no small feat. The purpose of this special issue, however, is not to show or seek unanimity among the contributors on how to operationalize learning disabilities. Rather, the focus is on the commonality of conceptual issues that emerges in our attempts to operationalize learning disabilities.
Hyperplane Envelopes and the Clairaut Equation

The subject of envelopes has been part of differential geometry from the beginning. This paper brings a modern perspective to the classical problem of envelopes of families of affine hyperplanes. In the process, the classical results are generalized and unified. A key step in this process is the use of “generalized immersions”. These have been described elsewhere but, briefly, every classical immersion defines a generalized immersion in a canonical way so that generalized immersions can be understood as ordinary immersions “with singularities.” Next, the concept of an envelope is given a modern definition, namely, an envelope is a generalized immersion solving the family that has a universal mapping property relative to all other full rank solutions. The beauty of this approach becomes apparent in the “Envelope Theorem”. With one mild assumption, namely that the associated family of linear hyperplanes is immersed, it is proven that a family of affine hyperplanes always has an envelope, and that envelope is essentially unique.
Teacher Training with a Twist: A Collaborative Project in North Carolina1

With the growing demand across the country for foreign language instruction in the elementary school, there is an urgent and increasing need for qualified teachers. One of the reasons for the current shortage of trained elementary school foreign language teachers is the serious shortage of qualified teacher educators. This article describes a three-year teacher training project that aimed to improve the training of elementary school foreign language teachers at institutions of higher education. The components of the training model were based on the principle that, in order to be successful, teacher trainers should have experience observing and teaching at the level for which they will be training others. The training model paired North Carolina teacher trainers with experienced elementary school teachers who served as their mentors. The teacher trainers participated in the following activities: 1) an intensive four-day seminar on elementary school foreign language methodology (also attended by their elementary school colleagues), 2) observations of their partners'elementary school language classes, 3) teaching of their partners'elementary school classes, 4) collaboration with the elementary school language teachers in the development of a teacher education curriculum, and 5) peer coaching with a new group of teacher trainers. These teacher educators were then responsible for incorporating the new material and methodologies into their universities' curricula and providing elementary school language instruction to undergraduate foreign language students preparing to become teachers.
Endogenous glucose production and lipolysis in anorexia nervosa—a study using stable isotope‐labelled compounds

Endogenous glucose production and lipolysis in anorexia nervosa--a study using stable isotope-labelled compounds.
The onset of chaos in vortex sheet flow

Regularized point-vortex simulations are presented for vortex sheet motion in planar and axisymmetric flow. The sheet forms a vortex pair in the planar case and a vortex ring in the axisymmetric case. Initially the sheet rolls up into a smooth spiral, but irregular small-scale features develop later in time: gaps and folds appear in the spiral core and a thin wake is shed behind the vortex ring. These features are due to the onset of chaos in the vortex sheet flow. Numerical evidence and qualitative theoretical arguments are presented to support this conclusion. Past the initial transient the flow enters a quasi-steady state in which the vortex core undergoes a small-amplitude oscillation about a steady mean. The oscillation is a time-dependent variation in the elliptic deformation of the core vorticity contours; it is nearly time-periodic, but over long times it exhibits period-doubling and transitions between rotation and nutation. A spectral analysis is performed to determine the fundamental oscillation frequency and this is used to construct a Poincar´ e section of the vortex sheet flow. The resulting section displays the generic features of a chaotic Hamiltonian system, resonance bands and a heteroclinic tangle, and these features are well-correlated with the irregular features in the shape of the vortex sheet. The Poincar´ e section also has KAM curves bounding regions of integrable dynamics in which the sheet rolls up smoothly. The chaos seen here is induced by a self-sustained oscillation in the vortex core rather than external forcing. Several well-known vortex models are cited to justify and interpret the results. Vortex sheets are commonly used in fluid dynamics to represent thin shear layers in slightly viscous flow (Batchelor 1967; Sa!man 1992). Here we present simulations of vortex sheet motion in planar and axisymmetric flow using a regularized point-vortex method. The initial condition corresponds to potential flow past either a flat plate or a circular disk, and the sheet rolls up to form a vortex pair in the planar case and a vortex ring in the axisymmetric case. The vortex pair is a model for the trailing wake behind an aircraft (Spalart 1998) and the vortex ring describes the starting flow discharged from a circular tube (Shari! & Leonard 1992; Lim & Nickels 1995). The present work is concerned with the long-time dynamics of the pair/ring. Vortex sheet simulations encounter a number of di"culties due to Kelvin‐Helmoltz instability and singularity formation (Birkho! 1961; Moore 1979; Krasny 1986). To overcome these di"culties, we represent the sheet as a set of regularized point vortices. This approach was originally developed for vortex sheet motion in planar flow (Chorin & Bernard 1973; Anderson 1985; Krasny 1987) and was later extended to the case of axisymmetric flow (Dahm, Frieler & Tryggvason 1992; Caflisch, Li & Shelley 1993).