cssi/SciSciGPT-SciSciNet huggingface dataset:
On the forces between phospholipid bilayers

Calculations for the free energy of interaction between phospholipid vesicles have been performed and applied to the question of vesicle aggregation. Calculations of van der Waals interactions have been performed by a computationally simple procedure based on an effective pair summation, which yields results close to those calculated with the Lifshitz theory. The equivalent (composition and distance dependent) Hamaker coefficients are in the range of 2 × 10−14−10−13 erg. Calculations of electrostatic energies of repulsion are based on detailed binding studies of calcium and magnesium to phosphatidylserine (PS). The binding of sodium to PS has also been considered. Total potential curves are computed for several vesicle systems at various concentrations of monovalent and divalent cations. Experimentally measured rates of aggregation of sonicated PS vesicles are shown to be explained by considering the existing potential barriers and hydrodynamic corrections. Predictions for both aggregation and stability, for various cationic environments, are shown to be verified by experiments. It is shown that the dimerization reaction of sonicated vesicles is expected to require surface contact; whereas, for large vesicles, aggregation may preferentially occur in a secondary minimum, with separations of several nanometers.
Taste Interrelationships. V. Sucrose, Sodium Chloride, and Citric Acid in Lima Bean Puréea

SUMMARY A highly trained panel of nine judges determined the taste interactions of supra threshold concentrations of sucrose, sodium chloride, and citric acid in lima bean puree. The results were in good agreement with previous results with solutions of distilled water, in which: 1) sucrose and citric acid exhibited a mutual masking effect, and 2) sucrose and sodium chloride produced mutual masking except for low levels of sodium chloride (0.05 and 0.10%), which slightly enhanced the apparent sweetness of 0.4 and 0.8% sucrose. Sodium chloride generally depressed sourness, but citric acid significantly increased the saltiness of all levels of sodium chloride. The large amount of individual-judge variation, especially in the acid-salt comparisons, is discussed.
Equivalent Gaussian measure whose R-N derivative is the exponential of a diagonal form

Abstract A simple necessary and sufficient condition, on a trace-class kernel K, is given in order to demonstrate the existence of a measurable (relative to the completed product σ-algebra) Gaussian process with covariance K. Using this result, sufficient conditions are given on the means and the covariances (relative to two equivalent (~) Gaussian measures P and Pλ) of a process X so that the Radon-Nikodým (R-N) derivative dp λ dP is the exponential of the diagonal form in X. Analogues of the last two results in the setup of Hilbert space are also proved.
Metabolism of extracellular ATP by rat parotid cells

Abstract ATP hydrolysis and the products of ATP metabolism were measured in intact rat parotid acini. The purpose was to determine the contribution of extracellular enzymes in metabolizing ATP and its metabolites. The total enzyme activity accounting for extracellular ATP breakdown was at least 75% dependent on added divalent cations, consistent with the presence of ectoATPase. Approximately 50% of the added ATP was hydrolysed in 1 h by the cells and this percentage was independent of cell protein concentration from 80 to 296 μg/ml and independent of ATP concentration from 4 to 80 μM. ADP, AMP and adenosine were identified as metabolites. Cell adenosine uptake was not a factor in controlling the levels of extracellular adenosine. Generation of adenosine was limited under conditions of higher rates of ATP hydrolysis. Studies in parotid cell membranes showed that very little feedback inhibition of ectoATPase was observed. 5′ Nucleotidase was present at levels of activity of 0.06–0.19 μmol/mg protein/h in intact acini. The results confirm the presence of ectonucleotidases which can generate ADP, AMP and adenosine. Ectonucleotidase could contribute to reducing the effect of extracellular ATP on the parotid cell.
Design of hard crystals

Abstract Hardness is measured by indenting, or by scratching, a solid. In general, it is a measure of structural stability which, in turn, is determined by elastic stiffness, plastic resistance, resistance to structure change; all of which vary with chemical bonding type (electronic structure). For maximum hardness, the key properties must be simultaneously maximized. Furthermore, hardness is a three-dimensional property, so the properties must be maximized in three-dimensions. Resistance to elastic strain depends primarily on valence-electron volumetric density, VED (electrons/unit volume). For sp bonding, the number of valence electrons simply equals the column number (I, II, III, or IV) of the Periodic Table. For the transition elements, there is no reliable rule. The bulk modulus increases with the VED, while the shear moduli are more complex. Resistance to plastic deformation depends primarily on dislocation mobility. This is determined by intrinsic factors in covalently bonded solids (semiconductors) and by extrinsic factors in metals. When a dislocation moves, the atomic symmetry at its core changes. This has a little effect in sp-bonded metals, but it profoundly affects the chemical bonding in covalent crystals. For maximum hardness, dislocation mobility must be minimized. The above principles have been applied to create a new material that easily scratches sapphire; namely, OsB 2 . It is believed that they can be used to create even harder materials.
Reducing the space-time complexity of the CMA-ES

A limited memory version of the covariance matrix adaptation evolution strategy (CMA-ES) is presented. This algorithm, L-CMA-ES, improves the space and time complexity of the CMA-ES algorithm. The L-CMA-ES uses the $m$ eigenvectors and eigenvalues spanning the m-dimensional dominant subspace of the n-dimensional covariance matrix, C, describing the mutation distribution. The algorithm avoids explicit computation and storage of $C$ resulting in space and time savings. The L-CMA-ES algorithm has a space complexity of \mathcal{O}(nm) and a time complexity of \mathcal{O}(nm^2). The algorithm is evaluated on a number of standard test functions. The results show that while the number of objective function evaluations needed to find a solution is often increased by using m
Hermetic wafer-level packaging for RF MEMs: Effects on resonator performance

The work presented here details the wafer-level fabrication and integration of aluminum nitride (AlN) micro resonators into hermetic micro environments. By etching cavities into the lid wafer and then bonding the lid wafer to a wafer of AlN micro resonators, a hermetic micro environment is created. After bonding, the lid wafer is thinned by plasma etching to expose individual die. This sequence presents the opportunity to perform resonator release on a wafer level while providing protection from dicing and other fabrication steps. We present here, fabrication and integration specifics on the wafer-level-packaging (WLP). Further we detail challenges encountered during the integration process including: elimination of micro voids created during eutectic wafer bonding, the use of plasma etching of lid wafers as a replacement to polish based wafer thinning, techniques to confirm hermetic environments, and significant failure mechanisms of the process limiting yield. Finally, we quantify improvements of the AlN micro resonators by correlating quality factors and integrated Pirani gauges.
Whole chest MRA and velocimetry for congenital heart disease in less than 10 minutes with 3D radial phase contrast

Introduction MRI of congenital heart disease (CHD) usually requires acquisition of multiple anatomical and functional scans followed by several 2D phase contrast (PC) acquisitions in various scan planes for flow measurements. A 3D PC technique using vastly undersampled isotropic projection reconstruction (PCVIPR) with respiratory gating allows for volumetric 3D flow imaging with high spatial and temporal resolution over a large field of view in less than ten minutes during free breathing. Previously shown to be accurate for renal MRA and quanitification of pressure gradients, we have recently extended this technique to thoracic MRA (Figure 1).
SU-F-18C-01: Minimum Detectability Analysis for Comprehensive Sized Based Optimization of Image Quality and Radiation Dose Across CT Protocols

Purpose: This work involved a comprehensive modeling of task-based performance of CT across a wide range of protocols. The approach was used for optimization and consistency of dose and image quality within a large multi-vendor clinical facility. Methods: 150 adult protocols from the Duke University Medical Center were grouped into sub-protocols with similar acquisition characteristics. A size based image quality phantom (Duke Mercury Phantom) was imaged using these sub-protocols for a range of clinically relevant doses on two CT manufacturer platforms (Siemens, GE). The images were analyzed to extract task-based image quality metrics such as the Task Transfer Function (TTF), Noise Power Spectrum, and Az based on designer nodule task functions. The data were analyzed in terms of the detectability of a lesion size/contrast as a function of dose, patient size, and protocol. A graphical user interface (GUI) was developed to predict image quality and dose to achieve a minimum level of detectability. Results: Image quality trends with variations in dose, patient size, and lesion contrast/size were evaluated and calculated data behaved as predicted. The GUI proved effective to predict the Az values representing radiologist confidence for a targeted lesion, patient size, and dose. As an example, an abdomen pelvis exam for the GE scanner, with a task size/contrast of 5-mm/50-HU, and an Az of 0.9 requires a dose of 4.0, 8.9, and 16.9 mGy for patient diameters of 25, 30, and 35 cm, respectively. For a constant patient diameter of 30 cm, the minimum detected lesion size at those dose levels would be 8.4, 5, and 3.9 mm, respectively. Conclusion: The designed CT protocol optimization platform can be used to evaluate minimum detectability across dose levels and patient diameters. The method can be used to improve individual protocols as well as to improve protocol consistency across CT scanners.
Electronically coupled MM quadruply-bonded complexes (M = Mo or W) employing functionalized terephthalate bridges: toward molecular rheostats and switches.

Toluene solutions of M2(O2CtBu)4 (M = Mo, W; 2 equiv) react with a range of functionalized terephthalic acids, HO2CArCO2H (Ar = C6H4, C6F4, C6Cl4, C6H2-2,5-Cl2, C6H2-2,5-(OH)2, C6H3-2-F), to give [(tBuCO2)3M2]2[μ-O2CArCO2]. These compounds show intense ML(bridge)CT absorptions in the visible region of the electronic spectrum, and the terephthalate bridge serves to electronically couple the two M2 units via interactions between the M2 δ and bridge π orbitals. Electronic structure calculations reveal how the degree of electronic coupling is controlled by the dihedral angles between the terephthalate C6 ring and the two CO2 units and the degree of interaction between the M4 δ MOs and the LUMO of the bridge. Both of these factors are controlled by the aryl substituents, and collectively these determine the thermochromism displayed by these complexes in solution together with the physical properties of the oxidized radical cations as determined by electrochemical studies (CV, DPV), UV−vis−NIR and EPR spectrosc...
Stimulus intensity and trace intervals in sensory preconditioning using the CER

Sixty-four rats were given preconditioning training (S1 -S2 pairings) with a trace interval of 0, 2, 5, or 8 sec and an S1 of either strong or mild intensity. Preconditioning was followed by conditioned emotional response (CER) training, with S2 used as a CS. The response measure used for analysis was the suppression of consummatory drinking in the presence of S1. The results indicated: (a) a significantly greater amount of suppression for strong S1 groups than for mild S1 groups, (b)no significant differences in suppression among groups receiving various trace-interval lengths, and (c) no significant interaction effects. It was concluded that the results were similar to effects obtained in comparable classical conditioning situations.
Effect of weathering and traffic exposure on removal of nitrogen oxides by photocatalytic coatings on roadside concrete structures

Oxides of nitrogen (NO x ) are ubiquitous pollutants in large urban areas of the world. Photocatalytic materials have been studied, primarily in the laboratory, for their ability to remove oxides of nitrogen. The study described herein compared NO x removal efficacies of three commercially-available photocatalytic coatings (a stucco, a white paint and a clear paint) applied to roadside concrete. The study aimed to elucidate how environmental parameters and exposure to real roadside conditions impact NO x removal. This was achieved through periodic laboratory chamber testing and material characterization of concrete slabs stored by busy roadways for a 20-month period. It was observed that roadside exposure led to physical degradation of the clear paint coating, while the other two remained intact. The stucco coating was the most effective at NO x removal, but the efficacy nonetheless diminished over time.
Incisional Hernia Repair: Laparoscopic Techniques

Repair of incisional hernias using the laparoscopic technique has continued to evolve since its inception in 1991. An analysis of the current literature has revealed that hernias as large as 1600 cm2 have been successfully repaired with this method. The average size appears to be about 105 cm2. Several choices of a biomaterial are available today, differing in the type of synthetic product or products that are used to manufacture them. Others incorporate an absorbable component. The goal of all of them is to prevent adhesion formation. The fixation devices that can be used are also varied. The results of laparoscopic incisional hernia repair are described. The conversion rate of these procedures is an impressive 2.4% with an enterotomy rate of 1.8%. These results affirm the low risk of this operation. The recurrence rate of 4.2% confirms the permanence of the repair. This procedure may become the standard of care in the near future.
Face Recognition under Varying Illumination with Logarithmic Fractal Analysis

Face recognition under illumination variations is a challenging research area. This paper presents a new method based on the log function and the fractal analysis (FA) to produce a logarithmic fractal dimension (LFD) image which is illumina- tion invariant. The proposed FA feature-based method is a very effective edge enhancer technique to extract and enhance facial features such as eyes, eyebrows, nose, and mouth. Our extensive experiments show the proposed method achieves the best recog- nition accuracy using one image per subject for training when compared to six recently proposed state-of-the-art methods.
Cultural Identity, Explanatory Style, and Depression in Navajo Adolescents.

This study investigated the interrelationships among cultural identity, explanatory style, and depression in Navajo adolescents. A total of 332 (197 female, 135 male) Navajo adolescents completed 7 self-report measures. These data were used to create, via structural equation modeling, a series of factor models and full structural models. Analyses indicated that current factor structures for explanatory style and depression are adequate for use with Navajo adolescents. Increased control and predictability and limited duration of stressful encounters were both predictive of decreased symptoms of depression. Higher levels of Navajo cultural identity had a modest effect in terms of reducing depression. Other factors, such as perceived discrimination and urban/reservation domicile, are important to study to provide an increased understanding of depression among Navajo adolescents.
A Study on Dynamics of 2-PRR Parallel Machine Tool Based on the Lagrange Equation

Based on the Lagrange equation, a dynamic equation of 2-PRR parallel machine tool has been established and the relation among displacement,velocity and acceleration of moving platform was given. By modeling and simulating on the simulink of Matlab, forword dynamics are solved. This paper also provide a reference for dynamics analysis and optimization of less freedom machine tool
Instructional Grouping for Reading for Students with LD Implications for Practice

Teachers' grouping practices during reading instruction can serve as a critical component in facilitating effective implementation of reading instruction and inclusion of students with disabilities in general education classes. In this article, we provide an overview of the recent research on grouping practices (whole class, small group, pairs, one-on-one) during reading instruction for students with disabilities. After discussion of each grouping format, implications for practice are highlighted with particular emphasis on instructional practices that promote effective grouping to meet the needs of all students during reading in general education classrooms.
RE-DESCRIPTION OF THECAMOEBA MUNDA SCHAEFFER 1926 (GYMNAMOEBIA, THECAMOEBIDAE), ISOLATED FROM THE BALTIC SEA

Summary The poorly known marine amoeba — Thecamoeba munda Schaeffer, 1926 (Gymnamoebia, Thecamoebidae) was found in the Sound (Baltic Sea). This species was initially described by A.A. Schaeffer in 1926 and since this time was not studied and re-described in terms of modern sytematics of gymnamoebae. Multiple photographs and a detailed re-description with re-diagnosis of T. munda are presented. The cell surface of this species is very similar to that of T. orbis — another marine Thecamoeba.
Unsupervised cosegmentation based on superpixel matching and Fastgrabcut

This paper proposes a novel unsupervised cosegmentation method which automatically segments the common objects in multiple images. It designs a simple superpixel matching algorithm to explore the inter-image similarity. It then constructs the object mask for each image using the matched superpixels. This object mask is a convex hull potentially containing the common objects and some backgrounds. Finally, it applies a new FastGrabCut algorithm, an improved GrabCut algorithm, on the object mask to simultaneously improve the segmentation efficiency and maintain the segmentation accuracy. This FastGrabcut algorithm introduces preliminary classification to accelerate convergence. It uses Expectation Maximization (EM) algorithm to estimate optimal Gaussian Mixture Model(GMM) parameters of the object and background and then applies Graph Cuts to minimize the energy function for each image. Experimental results on the iCoseg dataset demonstrate the accuracy and robustness of our cosegmentation method.
Advanced Motion Compensation Methods for Intravital Optical Microscopy

Intravital microscopy has emerged in the recent decade as an indispensible imaging modality for the study of the microdynamics of biological processes in live animals. Technical advancements in imaging techniques and hardware components, combined with the development of novel targeted probes and new mice models, have enabled us to address long-standing questions in several biology areas such as oncology, cell biology, immunology, and neuroscience. As the instrument resolution has increased, physiological motion activities have become a major obstacle that prevents imaging live animals at resolutions analogue to the ones obtained in vitro. Motion compensation techniques aim at reducing this gap and can effectively increase the in vivo resolution. This paper provides a technical review of some of the latest developments in motion compensation methods, providing organ specific solutions.
A Molecular Dynamics Analysis of Surface Interference and Tip Shape and Size Effects on Atomic-Scale Friction

Molecular dynamics simulations of a rigid diamond tip sliding on a face-centered-cubic copperlike substrate were performed in order to examine the dependence of the friction coefficient on the tip-substrate interference and the shape and size of the tip. For a square-base prismatic tip, the friction force is mainly due to interactions of atoms at the front face of the tip and substrate atoms ahead of the tip, while the normal force is due to interactions of atoms at the tip base and substrate atoms under the tip. However, for a pyramidal tip, both normal and friction forces are mainly due to interactions between atoms at the front face of the tip and substrate atoms in the vicinity of the sliding tip. Consequently, the friction coefficient is either sensitive (square-base prismatic tip) or insensitive (pyramidal tip) to the tip-substrate interference distance. In addition, tip size and orientation effects on the friction coefficient were observed with square- and triangle-base prismatic tips, respectively. Lower friction coefficients were obtained with a larger base area and edge-front sliding with a triangle-base prismatic tip. The results provide insight into atomic-scale friction anisotropies due to the effects of the tip size and shape and the tip-substrate interference.
500-GHz characterization of an optoelectronic S-parameter test structure

We propose a compact, high-bandwidth optoelectronic S-parameter test structure and characterize its performance via electrooptic sampling over a 500-GHz frequency range. The test structure is shown to be well-behaved over a 300-GHz bandwidth, with further improvement potential. Active devices can be wirebonded into the structure for characterization, or they can be integrated on-wafer for improved performance. >
Both aborted sudden cardiac death and end-stage phase in hypertrophic cardiomyopathy.

Abstract Hypertrophic cardiomyopthy is characterized by a diverse natural history in which patients may experience sudden cardiac death, often without antecedent symptoms 1–4 others have been described as experiencing an evolution to the “end-stage” of this disease, characterized by left ventricular wall thinning, cavity enlargement and impaired contractility. 1–5 Patients with either of these 2 phases of the natural history of hypertrophic cardiomyopathy may be closely related and thereby share the same genetic substrate. 6 In the present report, we describe 2 patients who had demonstrated a unique clinical course by virtue of experiencing both aborted tion of (and death resulting from) the end-stage phase of hypertrophic cardiomyopathy years later.
Addressing Obesity in Pregnancy: What Do Obstetric Providers Recommend?

Abstract Objective: Maternal obesity is associated with adverse pregnancy outcomes. To improve outcomes, obstetric providers must effectively evaluate and manage their obese pregnant patients. We sought to determine the knowledge, attitudes, and practice patterns of obstetric providers regarding obesity in pregnancy. Methods: In 2007–2008, we surveyed 58 practicing obstetricians, nurse practitioners, and certified nurse-midwives at a multispecialty practice in Massachusetts. We administered a 26-item questionnaire that included provider self-reported weight, sociodemographic characteristics, knowledge, attitudes, and management practices. We created an 8-point score for adherence to 8 practices recommended by the American College of Obstetricians and Gynecologists (ACOG) for the management of obese pregnant women. Results: Among the respondents, 37% did not correctly report the minimum body mass index (BMI) for diagnosing obesity, and most reported advising gestational weight gains that were discordant wi...
Reflections on caring for the long-stay inpatient.

Severely ill patients with refractory conditions complicated by disorganized or dangerous behavior remain in chronic wards ofstate hospitals. The need for long-term hospital care has been recognized ( 1,2); however, specific information about these long-stay inpatients and their treatment is rare. Given the expense involved and the clinical acuity and the sophistication required to develop treatment programs for heretofore refractory problems, this lack of information is unfortunate. In the past, the long-stay population generally included older patients with negative symptoms (3) and institutional stigmata who were primarily served by custodial models ofcare. The present long-stay population, however, often requires active treatment for refractory psychosis or severe character pathology complicated by behavioral dyscontrol, denial, and substance abuse (4). These patients have failed to tolerate less restrictive alternatives to hospitalization. They have been unable to negotiate issues of identity consolidation, relationships, self-esteem, vocation, and independence. Often they have become isolated from their families and home communities. They receive substantial doses of antipsychotic medications, often in combination with other agents (4); however, symptom control is incomplete, with persistence
An examination of the effects of mammillary-body lesions on reversal learning sets in monkeys

Monkeys with mammillary-body lesions were compared with operated and unoperated control monkeys on the acquisition of a series of place and object reversal discriminations. The animals with mammillary-body lesions were found not to differ from the control animals on either the initial acquisition of a place response or the visual discrimination of two junk objects. On subsequent reversals, however, monkeys with mammillary-body lesions were severely impaired on the spatial task, but showed no impairment in reversal learning in the object task. These results are consistent with our previous findings of an impairment in spatial alternation learning following mammillary-body lesions in monkeys and supports the hypothesis that the role of the mammillary nuclei in cognition may be limited to the spatial domain.
Progress in design and construction of the Optical Communications Telescope Laboratory (OCTL)

JPL is constructing an Optical Communications Telescope Laboratory (OCTL) at its Table Mountain Facility complex in the San Bernadino Mountains of Southern California. The OCTL will house a 1-m class telescope and serve as an R&D ground station supporting future optical communications demonstrations with Earth-orbiting satellites and deep space probes. It will also support research in adaptive optics, optical receiver technologies, and help in developing spacecraft acquisition and tracking strategies from future optical ground stations. The OCTL building was completed in November 1999, and Brashear-LP of Pittsburgh, PA has been selected to build the telescope. First light is expected in July 2001.
Decisions! Decisions! Decisions!:

Five important attributes of solving problems plus a rating scale to help clarify the acceptability of a given solution
Wastewater infrastructure for small cities in an urbanizing world: integrating protection of human health and the environment with resource recovery and food security.

The majority of population growth in developing countries will occur in small cities closely linked to agricultural zones, with poor access to water and sanitation. Wastewater management priorities in these regions will be different from those in larger cities and developed countries. Two wastewater treatment systems in Bolivia, one with an upflow anaerobic sludge blanket (UASB) reactor and polishing ponds, the other with three stabilization ponds, are assessed to determine their resource recovery potential. The UASB reactor produces biogas with 500–650 MJ per day. In six months, both systems discharge wastewater with the same mass of nutrients as fertilizers used to produce crops containing 10–75 days’ worth of the recommended food energy intake for each person using the system. Both systems also discharge detectable levels of helminth eggs, Giardia cysts, and Cryptosporidium oocysts, but the UASB reactor system discharges higher concentrations, implying limited reuse potential. From a regional managemen...
On nonautonomous linear systems of differential and difference equations with R-symmetric coefficient matrices

Abstract Let C n × n ( I ) denote the set of continuous n × n matrices on an interval I . We say that R ∈ C n × n ( I ) is a nontrivial k -involution if R = P ( ⊕ l = 0 k - 1 ζ l I d l ) P - 1 where ζ = e - 2 π i / k , d 0 + d 1 + ⋯ + d k - 1 = n , and P ′ = P ⊕ l = 0 k - 1 U l with U l ∈ C d l × d l ( I ) . We say that A ∈ C n × n ( I ) is R -symmetric if R ( t ) A ( t ) R - 1 ( t ) = A ( t ) , t ∈ I , and we show that if A is R -symmetric then solving x ′ = A ( t ) x or x ′ = A ( t ) x + f ( t ) reduces to solving k independent d l × d l systems, 0 ⩽ l ⩽ k - 1 . We consider the asymptotic behavior of the solutions in the case where I = [ t 0 , ∞ ) . Finally, we sketch analogous results for linear systems of difference equations.
Measurement of Stray Light in a Monochromator

In spectrophotometry and spectroradiometry photometric errors due to stray light passed by the monochromator employed are always present to some degree. The magnitude of the errors is dependent upon the spectral distribution of the energy entering the monochromator, the stray light characteristics of the monochromator, the effects of any filters or other components between the monochromator and the phototube, and the spectral response of the phototube or other receptor. Means are outlined of measuring the stray light characteristics of a monochromator and expressing the results in the form of a table or grid of numbers. From the grid values it is a relatively simple process to estimate closely the photometric errors in any given application. Finally, various means are suggested of reducing the effects of stray light errors.
The maximum effect of an increase in rate on human ventricular refractoriness.

MORADY, F., ET AL.: The maximum eifect of an increase in rate on human ventricular refractoriness. The purpose of this study was to determine the maximum shortening of ventricular refractoriness that occurs following an increase in rate and to quantitate the duration of ventricular pacing required to obtain this maximum shortening of refractoriness. The subjects of the study consisted of 41 patients who underwent a clinically indicated electrophysiologic study. Ventricular refractory periods were measured with an extrastimulus (S2) at basic cycle lengths of 600 and 400 ms by Method A (8 beat basic drive trains and 4 second intertrain paue and Method B (drive train duration of 3 minutes, then an S2 after every eighth basic drive beat, with no pause after the S2). In 23 subjects, the mean ventricular effective refractory period determined by Method B was 12 ± 7 ms (± standard deviation) shorter than when determined by Method A at a basic drive cycle length of 600 ms (p < 0.0001] and 33 ± 9 ms shorter at a basic drive cycle length of 400 ms (p < 0.001]. In these 23 subjects, the drive train duration required for maximum shortening of ventricular refractoriness was estimated by counting the number of drive train beats preceding ventricular capture by an S2 inserted after every fourth basic drive beat at a coupling interval fixed at 5 ms longer than the ventricuiar effective refractory period determined in that subject by Method B. The mean number of basic drive beats preceding capture by S2 was 114 ±84 beats at a basic drive cycle length of 600 ms and 233 ± 85 beats at a BDCL of 400 ms. In six subjects the ventricuiar effective refractory period was measured by Methods A and B before and after autonomic blockade with propranoiol and atropine, and the amount of shortening in the ventricular effective refractory period with Method B was not affected by autonomic blockade. In conclusion, the basic drive train has a cumulative effect on ventricular refractoriness in humans, and a drive train duration substantially longer than 50 beats often is required to obtain the maximum shortening of ventricuiar effective refractory period after an increase in rate. Therefore, ventricular effective refractory periods determined conventionally using 8 beat drive trains and a 4 second intertrain pause often may be overestimates of the actual ventricular effective refractory period. The shortening of ventricuiar refractoriness with long drive train durations is probably related to a prolonged duration of pacing required to obtain a steady-state action potential duration after an increase in rate. (PACE, Vol. 11, December 1988] ventricular refractoriness, autonomic blockade, drive train duration
Path-integral computation of superfluid densities

The normal and superfluid densities are defined by the response of a liquid to sample boundary motion. The free-energy change due to uniform boundary motion can be calculated by path-integral methods from the distribution of the winding number of the paths around a periodic cell. This provides a conceptually and computationally simple way of calculating the superfluid density for any Bose system. The linear-response formulation relates the superfluid density to the momentum-density correlation function, which has a short-ranged part related to the normal density and, in the case of a superfluid, a long-ranged part whose strength is proportional to the superfluid density. These facts are discussed in the context of path-integral computations and demonstrated for liquid $^{4}\mathrm{He}$ along the saturated vapor-pressure curve. Below the experimental superfluid transition temperature the computed superfluid fractions agree with the experimental values to within the statistical uncertainties of a few percent in the computations. The computed transition is broadened by finite-sample-size effects.
Progesterone, 17 beta-estradiol, and opioid neuropeptides modulate pattern of luteinizing hormone in circulation of the cow.

The working hypothesis for this study was that 17p-estradiol (E 2 ), progesterone (P4), and opioid neuropeptides modulate frequency of pulsatile release of LH during the luteal phase of the bovine estrous cycle. On Day 8 of the estrous cycle (Day 0 = estrus), 20 cows were ovariectomized (OVX) and immediately received one of three steroid replacement treatments: P 4 alone (n = 6), E2 alone (n = 7), or P 4 and E, (n = 7). To characterize the pattern of LH in peripheral circulation, serial blood samples were collected (12-min intervals for 22 h) on the fifth day following OVX. LHRH was administered after the 22-h sample was taken. Naloxone (opioid neuropeptide antagonist; 0.5 mg/kg) was administered on the sixth day after OVX, and change of concentration of LH in peripheral circulation was monitored. Pulse frequency of LH and mean concentration of LH were lower (p < 0.01) in cows treated with P4 and E, compared to cows treated with P 4 alone. Moreover, cows treated with E alone had a greater (p < 0.01) frequency of LH pulses and mean concentration of LH compared to cows treated with P 4 alone. The greatest amplitude (p < 0.01) of LH release after LHRH was in cows treated with E, alone. The greatest percentage increase (p < 0.01) in LH after administration of naloxone occurred in cows treated with P4 alone. In conclusion, in cows treated with doses of P4 and E2 that resulted in circulating concentrations of these hormones typical of the midluteal phase of the estrous cycle, pulses of LH were fewer than in cows treated with P4 alone; in cows treated with P 4 alone, pulses of LH were fewer than in cows treated with E, alone. The responsiveness of the pituitary to LHRH is greater in cows treated with E, alone than in cows treated with P 4 alone or with the combination of P 4 and E,. Endogenous opioid inhibition of LH secretion was greater in cows treated with P 4 alone compared to cows treated with P4 and E, or with E alone.
Linearization of EER RF power amplifiers using an adaptive subband predistorter

Power amplifiers are a fundamental component for nearly all communications systems. Long-range wireless communications require high-power radio frequency (RF) amplifiers that are by far the most power consuming devices in the entire system. It is well known that efficient power amplifiers are highly nonlinear. However, highly efficient amplifiers such as the envelope elimination and restoration (EER) amplifiers as described herein are critical to mobile communications systems that require low power consumption for increased battery life and reduced size, weight, and power (SWAP), such as cell phones and military radios. The non-linearity of amplifiers generates both in-band noise (IBN) and out-of-band noise (OBN) which causes an increased bit error rate (BER) and adjacent channel interference (ACI), respectively. This degradation in performance has become a critical issue in recent years as newly emerging spectrally-efficient digital waveforms are being used for high-data rate communications. Linearization is necessary to comply with adjacent channel spectral mask requirements, to reduce BER, and to achieve acceptable amplifier efficiency. Predistortion can be used to convert a nonlinear amplifier into a linear amplifier. This paper describes a novel method for linearizing EER RF power amplifiers using adaptive subband predistortion.
Experimental infection of chimpanzees with the virus of hepatitis B.

THE effects of viral hepatitis in chimpanzees are similar to those in man1,2, and the disease can be transmitted from chimpanzees to humans3. Hepatitis B or Australia antigen (HBAg) has been reported in healthy chimpanzees4 and we have demonstrated antibody (HBAb) in 55% of these animals by radioimmunoassay. We have also shown the immunological identity between human and chimpanzee HBAg and HBAb5. Two susceptible chimpanzees (Xat and Yon) were inoculated intravenously with 1.0 ml. of a 1 : 10 dilution of human plasma containing HBAg and known to cause hepatitis B in humans. The animals were bled three times weekly and liver biopsies were obtained twice monthly in order to study immunological, biochemical, and histological responses. To determine HBAg, matrix gel diffusion (MGD)6, complement fixation (CF)7, radioimmunoassay (RIA)8 and passive haemagglutination (HA)9 techniques were used. To detect HBAg, the CF and MGD tests were used in addition to a “solid phase direct” radioimmunoassay system. Chimpanzee susceptibility to hepatitis B virus was inferred from a lack of demonstrable HBAb in serum by both HA and RIA techniques. Serum titre of HBAg in the diluted human plasma inoculum was 1 : 128 by the CF technique.
Comments and additions to "Robust transmission of unbounded strings using Fibonacci representations

An ambiguous point in the paper by Apostolico and Fraenkel (see ibid., vol.IT-33, no.2, p.238-45, March 1987) is clarified. New codes that have better asymptotic performances and better synchronization capability are introduced. >
Some properties of Ni-Cu foils and their behavior when heated in hydrogen

Nickel foils of nominal thickness 0.1 and 1 micron have been resistively evaporated onto copper-foil substrates of thickness 25 and 2.5 microns. In depositions in which the pressure was as high as 0.00001 torr, the deposited nickel was not shiny and appeared granular in a 100x microscope. Foils evaporated in higher vacuums were shiny, but became granular if heated to 500 C in oxygen at pressures greater than 0.000005 torr, or in carbon dioxide at pressures greater than 0.0000005 torr. This phenomenon has been interpreted as recrystallization. Foils heated to 500 C at pressures of hydrogen above 0.0003 torr exhibit cracking characteristic of hydrogen embrittlement. The bimetallic foils curled concave toward the nickel during evaporation, consistent with a connected-island form of film growth.
Sequenced reinforcement in a two-way runway situation

Capaldi’s (1963, 1964) sequential response hypothesis was tested with a within-Ss experimental design. A two-way runway situation made it possible for Ss to experience one sequence of reinforcements and nonreinforcements while running in one direction and another sequence while running in the opposite direction. The direction in which Ss ran alternated from trial to trial. The sequences Ss experienced in the two directions were an N-length of 3 (always 3 nonreinforced trials before a reinforced trial) or N-lengths of 1, 2, and 3 (either 1, 2, or 3 nonreinforcements before a reinforced trial). Greater resistance to extinction occurred in the direction that was associated with N-lengths of 1, 2, and 3.
Study of defects in LEC-grown undoped SI-GaAs by thermally stimulated current spectroscopy

Abstract Thermally stimulated current spectroscopy (TSC) reveals at least six traps in LEC semi-insulating GaAs. The relative concentrations of the traps are related to the native defect complexes expected from growth stoichiometry and subsequent annealing conditions. Variations of the sample conditions prior to the TSC scan are found to provide some evidence as to nature of the traps observed and also appear to cause photo-induced defect reactions.
OVINE FETAL LEUCINE AND PROTEIN METABOLISM DURING MATERNAL ANEMIA.† 1877

Maternal hypoxia reduces the availability of oxygen to the fetus, a reduction accompanied by decreased protein synthesis and reduced protein accretion. However, there is no evidence to show whether these effects are unique to maternal hypoxia or also occur when fetal oxygen availability is reduced by other means. To find if maternal anemia, a condition that also decreases fetal oxygen availability affects fetal protein metabolism, we measured fetal protein metabolism by infusion of 1-14C-leucine in seven chronically prepared fetal sheep. Following control measurements, the ewes' hematocrit was reduced from 31.7±1.5% to 12.3±0.4% by isovolemic exchange transfusion. The decreased fetal oxygen availability associated with maternal anemia affected fetal leucine metabolism in a manner somewhat different than that previously reported for maternal hypoxia. Both conditions decreased fetal leucine uptake. Oxidation of leucine fell during maternal anemia, an effect not reported during maternal hypoxia. Fetal protein metabolism was also affected slightly differently. Maternal anemia reduced not only protein synthesis (an effect reported during maternal hypoxia) but also decreased fetal protein breakdown. Regardless of the method used to decrease oxygen availability, fetal protein accretion fell, a finding incompatable with normal fetal growth. Table
Obesity is an independent contributor to functional capacity and inflammation in systemic lupus erythematosus

Objective. Obesity induces a proinflammatory state and is a major cause of morbidity in the general population. However, little is known about the effects of obesity in patients with chronic inflammatory illnesses such as systemic lupus erythematosus (SLE). Methods. One hundred consecutive patients with SLE were studied to determine the relationship between body mass index (BMI) and functional capacity, measures of fatigue, quality of life, and the inflammation markers C-reactive protein (CRP), the erythrocyte sedimentation rate, and interleukin-6 (IL-6). The association between BMI and patient characteristics was determined, and multiple logistic regression models were used to adjust for age, sex, disease activity, and diseaserelated damage. Results. Thirty-three patients had a normal BMI ( 30 kg/m 2 ). Obese patients had worse functional capacity, more fatigue, and higher concentrations of inflammation markers. The mean SD modified Health Assessment Questionnaire (M-HAQ) score was 0.6 0.4 in obese patients compared with 0.3 0.4 and 0.2 0.3 in overweight patients and those with a normal BMI, respectively (P 0.001). The mean SD concentrations of CRP in obese patients (10.0 8.6 mg/liter) were higher than those in patients who were overweight (4.7 5.4 mg/liter) or had a normal BMI (6.2 9.9 mg/liter) (P < 0.001). Similarly, concentrations of IL-6 were higher in obese patients (P 0.003). After adjusting for age, sex, disease activity, and damage indices, the associations between BMI and CRP (P < 0.001), M-HAQ scores (P 0.005), and IL-6 concentrations (P 0.01) remained significant. Conclusion. Obesity is independently associated with impaired functional capacity and inflammation markers in patients with lupus. Thus, weight loss may improve functional capacity and decrease cardiovascular risk factors.
Factors of Empowerment for Women in Recovery from Substance Use

Empowerment is an interdisciplinary construct heavily grounded in the theories of community psychology. Although empowerment has a strong theoretical foundation, few context-specific quantitative measures have been designed to evaluate empowerment for specific populations. The present study explored the factor structure of a modified empowerment scale with a cross-sectional sample of 296 women in recovery from substance use who lived in recovery homes located throughout the United States. Results from an exploratory factor analysis identified three factors of psychological empowerment which were closely related to previous conceptualizations of psychological empowerment: self-perception, resource knowledge and participation. Further analyses demonstrated a hierarchical relationship among the three factors, with resource knowledge predicting participation when controlling for self-perception. Finally, a correlational analysis demonstrated the initial construct validity of each factor, as each factor of empowerment was significantly and positively related to self-esteem. Implications for the application of psychological empowerment theory and research are discussed.
Anhydrous and Water-Assisted Proton Mobility in Phosphotungstic Acid

Nonlocal gradient-corrected density functional theoretical calculations were used to determine the energetics associated with proton migration in phosphotungstic acid. The activation energy for anhydrous proton hopping between two oxygen atoms on the exterior of the molecular Keggin unit was calculated to be 103.3 kJ mol-1. The quantum-tunneling effect on the rate of proton movement was determined using semiclassical transition-state theory and was found to be a major contributor to the overall rate of proton movement at temperatures below approximately 350 K. The adsorption of water on an acidic proton decreases the activation barrier for hopping to 11.2 kJ mol-1 by facilitating proton transfer along hydrogen bonds. The overall rate constant for proton hopping was determined as a function of temperature and water partial pressure. Small amounts of water greatly enhance the overall rate of proton movement.
Error in shear‐wave polarization and time splitting

Shear-wave polarization and time delay are attributes commonly used for fracture detection and characterization. In time-lapse analysis these parameters can be used as indicators of changes in the fracture orientation and density. Indeed, changes in fracture characteristics provide key information for increased reservoir characterization and exploitation. However, relative to the data uncertainty, is the comparison of these parameters over time statistically meaningful? We present the uncertainty in shear-wave polarization and time delay as a function of acquisition uncertainties, such as receiver and source misorientation, miscoupling and band-limited random noise. This study is applied to a time-lapse borehole seismic survey, recorded in Vacuum Field, New Mexico. From the estimated uncertainties for each survey, the uncertainty in the difference between the two surveys is 31° for the shear-wave polarization angle and 4 ms for the shear-wave time delay. Any changes in these parameters greater than these error estimates can be interpreted with confidence. This analysis can be applied to any time-lapse measurement to provide an interval of confidence in the interpretation of shear-wave polarization angles and time splitting.