cssi/SciSciGPT-SciSciNet huggingface dataset:
Phase discontinuities underlie increased drowsiness and diminished sleep quality in older humans

Abstract Healthy humans switch seamlessly between activity states, wake up and fall asleep with regularity, and cycle through sleep stages necessary for restored homeostasis and memory consolidation each night. This study tested the hypothesis that such smooth behavioral transitions are accompanied by smooth transitions between stable neural states within the brain. A method for detecting phase discontinuities across a broad range of frequencies was created to quantify phase disruptions in the Fp-Cz EEG channel from 20 annotated sleep files. Phase discontinuities decreased with increasingly deep sleep, and increased phase discontinuity was associated with increased drowsiness, reduced deep sleep, and shorter REM sleep. A 10s phase discontinuity summary measure (the phase jump indicator) closely tracked the annotated sleep stages and enabled discrimination between short ( Significance statement Evidence continues to accumulate regarding the positive relationship between healthy sleep and brain function. Recent studies also show that more healthful sleep can be induced with timely application of non-invasive therapies. Accordingly, the ability to accurately assess sleep quality in real-time has become increasingly important. Here, a newly defined measure, referred to as phase discontinuity, enabled rapid identification of unhealthful neural patterns associated with increased drowsiness, reduced deep sleep, and early termination of REM sleep. Moreover, the measure was linked to underlying neuronal and circuit properties known to impact sleep quality. Thus, the phase discontinuity measure defined in this study provides new insight into sleep pathology and has potential implications for closed-loop therapeutic intervention.
Numerical investigation of metrics for epidemic processes on graphs

This study develops the epidemic hitting time (EHT) metric on graphs measuring the expected time an epidemic starting at node a in a fully susceptible network takes to propagate and reach node b. An associated EHT centrality measure is then compared to degree, betweenness, spectral, and effective resistance centrality measures through exhaustive numerical simulations on several real-world network data-sets. We find two surprising observations: first, EHT centrality is highly correlated with effective resistance centrality; second, the EHT centrality measure is much more delocalized compared to degree and spectral centrality, highlighting the role of peripheral nodes in epidemic spreading on graphs.
Sustainable Chemistry: Solubilization of Phosphorus from Insoluble Phosphate Material Hydroxyapatite with Ozonized Biochar

A large increase in phosphorus (P) solubilization from hydroxyapatite using ozonized biochar has now been experimentally demonstrated here for the first time. Briefly, incubation of insoluble phosp...
Spacetime and Uncomplexity

Now I want to return to the gravitational aspects of complexity, or more to the point, the gravitational aspects of uncomplexity.
A Culturally Responsive Curricular Revision to Improve Engagement and Learning in an Undergraduate Microbiology Lab Course

We seek to increase student engagement and success to subsequently lead to increased retention and degree attainment for students at our Hispanic-serving institution. We hypothesized that using a culturally responsive approach in an undergraduate microbiology lab would increase engagement and learning gains. Using a culturally responsive approach allowed students to start their learning from their own place of understanding-centering students' lived experiences. Students interviewed family members to learn about "home remedies," and then devised experiments to test whether those home remedies affected growth of bacteria commonly implicated in gastrointestinal distress (Staphylococcus aureus, Bacillus cereus, and Escherichia coli) or sore throat (Neisseria gonorrhoeae, Streptococcus pyogenes, and Mycoplasma pneumoniae). As a final assessment, students generated project posters which they presented at a class symposium. Implementation of a culturally responsive research experience focused on the gut microbiome resulted in increased learning gains as evidenced by movement up Bloom's Revised Taxonomy Scale. Student feedback indicated increased engagement, increased confidence in communicating science and a deeper understanding and appreciation for microbiology. Taken together, the results indicate that students appreciate a more culturally responsive and student-centered approach to learning in microbiology and encourages expansion of this approach to other modules in the course. This paper includes responsive data to support this claim, as well as a sample course calendar and supplementary learning material to support the human microbiome approach to microbiology.
EFFICIENT COSMIC RAY ACCELERATION, HYDRODYNAMICS, AND SELF-CONSISTENT THERMAL X-RAY EMISSION APPLIED TO SUPERNOVA REMNANT RX J1713.7-3946

We model the broadband emission from supernova remnant (SNR) RX J1713.7-3946 including, for the first time, a consistent calculation of thermal X-ray emission together with non-thermal emission in a nonlinear diffusive shock acceleration model. Our model tracks the evolution of the SNR including the plasma ionization state between the forward shock and the contact discontinuity. We use a plasma emissivity code to predict the thermal X-ray emission spectrum assuming the initially cold electrons are heated either by Coulomb collisions with the shock-heated protons (the slowest possible heating), or come into instant equilibration with the protons. For either electron heating model, electrons reach 107 K rapidly and the X-ray line emission near 1 keV is more than 10 times as luminous as the underlying thermal bremsstrahlung continuum. Since recent Suzaku observations show no detectable line emission, this places strong constraints on the unshocked ambient medium density and on the relativistic electron-to-proton ratio. For the uniform circumstellar medium (CSM) models that we consider, the low densities and high relativistic electron-to-proton ratios required to match the Suzaku X-ray observations definitively rule out pion decay as the emission process producing GeV-TeV photons. We show that leptonic models, where inverse-Compton scattering against the cosmic background radiation dominates the GeV-TeV emission, produce better fits to the broadband thermal and non-thermal observations in a uniform CSM.
Wellness tourism competences for curriculum development: a Delphi study

A Delphi Study was conducted to identify competencies and values for entering level managers in the wellness tourism industry. The study comprised three rounds commencing 31 January 2018 and ending...
Mens Rea, Competency to Stand Trial, and Guilty but Mentally Ill.

The recent U.S. Supreme Court case of Kahler v. Kansas determined that the Kansas mens rea laws were sufficient to stand as the state’s only insanity defense statute. In this issue of The Journal, Landess and Holoyda describe the legal reasoning that led to this decision and the persistent concerns about the wisdom of the decision. This commentary is meant to serve as a mirror image to Landess and Holoyda’s article, as it focuses on the impact of Kahler on severely mentally ill individuals faced with criminal charges in the four mens rea states: Montana, Idaho, Utah, and Kansas. The authors assert that the absence of a traditional insanity defense disrupts the criminal justice process, adds the pressure of greater numbers of individuals pushed into the competency-to-stand-trial and competency-restoration systems, resurrects the guilty but mentally ill verdict from the condemnation of history, and forces people with serious mental iillness into prisons without any evidence that the prisons are up to the task of adequately caring for them.
Adapting Palliative Care Skills to Provide Substance Use Disorder Treatment to Patients With Serious Illness

Background:The majority of Palliative Care (PC) clinicians report recently caring for a person with a Substance Use Disorder (SUD). The impact of an untreated SUD is associated with significant suf...
Types I, II, III, and IV Stilling Basin Performance for Stepped Chutes Applied to Embankment Dams

AbstractScientists at the USDA Agricultural Research Service (ARS) Hydraulic Engineering Research Unit (HERU) conducted research on physical models of stilling basins (i.e., Types I, II, III, and I...
Comparison of Classification Methods for Time-Series Detection of Perspiration as a Liveness Test in Fingerprint Devices

Fingerprint scanners may be susceptible to spoofing using artificial materials, or in the worst case, dismembered fingers. An anti-spoofing method based on liveness detection has been developed for use in fingerprint scanners. This method quantifies a specific temporal perspiration pattern present in fingerprints acquired from live claimants. The enhanced perspiration detection algorithm presented here improves our previous work by including other fingerprint scanner technologies, using a larger, more diverse data set, and a shorter time window. Several classification methods were tested on fingerprint images from 33 live subjects, 33 spoofs created with dental material and Play-Doh, and 14 cadaver fingers. Each method had a different performance with respect to each scanner and time window. However, all the classifiers achieved approximately 90% classification rate for all scanners, using the reduced time window and the more comprehensive training and test sets.
Nickel‐Catalyzed Enantioselective Negishi Cross‐Couplings of Racemic Secondary α‐Bromo Amides with Alkylzinc Reagents: (S)‐N‐Benzyl‐7‐Cyano‐2‐Ethyl‐N‐Phenylheptanamide

6-Bromohexanitrile Zinc N-Benzyl-2-bromo-N-phenylbutanamide Nickel(II) chloride, dimethoxyethane adduct R-i-Pr-Pybox (S)-N-Benzyl-7-cyano-2-ethyl-N-phenylheptanamide Keywords: nickel catalyst; enantioselective Negishi cross coupling; racemic a-bromo amides; aklyzinc reagents; secondary electrophiles; stereoconvergent Negishi cross coupling; waste disposal
Unraveling in a repeated moral hazard model with multiple agents

This paper studies an infinite-horizon repeated moral hazard problem where a single principal employs several agents. We assume that the principal cannot observe the agents’ effort choices; however, agents can observe each other and can be contractually required to make observation reports to the principal. Observation reports, if truthful, can serve as a monitoring instrument to discipline the agents. However, reports are cheap talk so that it is also possible for agents to collude, i.e., where they shirk, earn rents, and report otherwise to the principal. The main result of the paper constructs a class of collusion-proof contracts with two properties. First, equilibrium payoffs to both the principal and the agents approach their first-best benchmarks as the discount factor tends to unity. These payoff bounds apply to all subgame perfect equilibria in the game induced by the contract. Second, while equilibria themselves depend on the discount factor, the contract that induces these equilibria is independent of the discount factor.
Some Aspects of the High Temperature Performance of Ceramics and Ceramic Composites

Ceramics and ceramic composites are subject to creep rupture at elevated temperatures. The rupture strain in such materials has been shown to exhibit a major transition, from creep brittleness to creep ductility. The emphasis of the present article is on the definition of microstructures that provide ductility. For this purpose, the fundamental principles involved in high temperature flow and fracture are reviewed, and physical models of the ductile-to-brittle transition are presented. The mechancial phenomena involved in these considerations include: creep crack growth, crack blunting, flaw nucleation and stress corrosion.
The role of proper motions in determining the luminosity and density functions.

The papers presented this morning form a good illustration of the old adage that you should never publish a paper that is completely correct, for then you can write only one paper. But if you publish a paper with a lot of errors, you are sure to be criticized, and you can write a second paper to answer your critics, and if the heat proves to be too much you can write a third paper withdrawing everything.
L-PYRROLIDONE CARBOXYLIC ACID CONTENT IN MAMMALIAN EPIDERMIS AND OTHER TISSUES

The total pyrrolidone carboxylic acid (PCA) and free amino acid concentration was determined in epidermis of five mammalian species, as well as in other tissues and body fluids of albino guinea pigs. PCA was found to be a major soluble nitrogen compound in epidermis of all species studied with concentrations of 186, 50, 31, 21, and 19 μmoles/gm wet wt in guinea pig, human, dog, rat, and mouse, respectively. Much lower levels of PCA (2-4 μmoIe/gm wet wt) were present in guinea-pig kidney, liver, pancreas, spleen, intestine, and brain. Guinea-pig red blood cells contained about 0.8 μmole PCA/gm and plasma about 0.3 μmole/ml. Optical rotatory dispersion studies on purified PCA isolated from albino guinea-pig epidermis showed it to be the "L" isomer. The possible origins of epidermal PCA are discussed.
Quality evaluation of packaged acidified vegetables subjected to continuous microwave pasteurization

Abstract The study evaluated the use of 915 MHz continuous microwave processing with a rotation apparatus for pasteurization of acidified vegetable packages. Broccoli florets, and 1.2 cm cubes of broccoli stems, red bell pepper, and sweetpotato were pre-equilibrated to 1 g/100 g NaCl and 0.38 g/100 mL citric acid, and separately placed in 110 mL cups with a 0.5 g/100 mL citric acid solution. Unsealed packages were placed on a conveyor belt and run through a 915 MHz microwave cavity operating at 3.5 kW (residence time = 4 min). After processing, cups were sealed with a lidding film, and held in insulating molds for 30 min. Infrared thermocouples, fiber optic temperature sensors, and infrared imaging were used to monitor product temperatures. Microbial stability and changes in color and instrumental textural properties were measured over a 60-day storage period at 30 °C. Good retention of color and texture of acidified vegetable pieces was observed after microwave pasteurization. Over storage, textural properties significantly degraded for all vegetables, but the brilliant color of red bell pepper and sweetpotato was relatively retained. Chemical indicators of microbial spoilage were not detected at the end of storage. This study demonstrates a successful continuous microwave pasteurization process for producing shelf-stable acidified vegetable packages.
Toward systems that understand spoken language

MIT's Voyager system is an attempt to explore issues related to a fully interactive spoken-language system and natural language understanding. The system helps users get from one location to another within a specific geographical area, and can provide information about certain objects in the area. The current version of Voyager focuses on the city of Cambridge, Massachusetts, between MIT and Harvard University. Voyager's domain knowledge (or backend) is an enhanced version of an existing direction assistance program (J.R. Davis and T.F. Trobaugh, 1987). The map database includes the locations of various classes of objects (streets, buildings, rivers) and their properties (address, phone number, etc.). To retrieve information, the Summit speech recognition system converts the user's speech signal into a set of word hypotheses, the Tina natural language system interacts with Summit to obtain a word string and a linguistic interpretation of the utterance, and an interface between the two subsystems converts Tina's semantic representation into the appropriate function calls to the back-end. Voyager then responds with a map, highlighting the objects of interest, plus an textual and spoken answer. The current implementation has a vocabulary of about 350 words and can deal with various types of queries, such as the location of objects, simple properties of objects, how to get from one place to another, and the distance and travel time between objects. >
Using a computerized conferencing system as a laboratory tool

Computerized Conferencing Systems are a new communications medium which offer an opportunity for geographically dispersed groups of persons to communicate regularly and to interact and make decisions as a group. They also include an embedded language which makes it possible to program and conduct fully automated experiments on group communication processes. The system thereby becomes a "laboratory without walls" which can be transported to the subjects.This paper reviews the methodological aspects of the first of a series of controlled "laboratory" experiments on the effects of the medium on small group communication processes. It focusses on the potentials for use of such systems as a tool for conducting communication experiments. The findings of the experiment itself will be reported more fully elsewhere.
On-policy concurrent reinforcement learning

When an agent learns in a multi-agent environment, the payoff it receives is dependent on the behaviour of the other agents. If the other agents are also learning, its reward distribution becomes non-stationary. This makes learning in multi-agent systems more difficult than single-agent learning. Prior attempts at value-function based learning in such domains have used off-policy Q-learning that do not scale well as the cornerstone, with restricted success. This paper studies on-policy modifications of such algorithms, with the promise of scalability and efficiency. In particular, it is proven that these hybrid techniques are guaranteed to converge to their desired fixed points under some restrictions. It is also shown, experimentally, that the new techniques can learn (from self-play) better policies than the previous algorithms (also in self-play) during some phases of the exploration.
AN EVALUATION OF ECONAZOLE, AN ANTIFUNGAL AGENT, FOR USE IN QUANTITATIVE CELL CULTURE EXPERIMENTS

Econazole, an imidazole derivative with high antifungal activity, was tested for cytotoxicity using five sensitive tests of human cell function in vitro: colony forming efficiency, growth rate, cell cycle distribution of a permanent epithelioid cell line (T-1E), and attachment efficiency and urokinase production by early passage human embryonic kidney cells. None of these endpoints was detectably affected by 1 μg/ml Econazole in serum containing medium. At 3 μg/ml, Econazole reduced slightly the growth rate of T-1E cells but did not detectably affect the other end points.
Photorealistic rendering of rain streaks

Photorealistic rendering of rain streaks with lighting and viewpoint effects is a challenging problem. Raindrops undergo rapid shape distortions as they fall, a phenomenon referred to as oscillations. Due to these oscillations, the reflection of light by, and the refraction of light through, a falling raindrop produce complex brightness patterns within a single motion-blurred rain streak captured by a camera or observed by a human. The brightness pattern of a rain streak typically includes speckles, multiple smeared highlights and curved brightness contours. In this work, we propose a new model for rain streak appearance that captures the complex interactions between the lighting direction, the viewing direction and the oscillating shape of the drop. Our model builds upon a raindrop oscillation model that has been developed in atmospheric sciences. We have measured rain streak appearances under a wide range of lighting and viewing conditions and empirically determined the oscillation parameters that are dominant in raindrops. Using these parameters, we have rendered thousands of rain streaks to create a database that captures the variations in streak appearance with respect to lighting and viewing directions. We have developed an efficient image-based rendering algorithm that uses our streak database to add rain to a single image or a captured video with moving objects and sources. The rendering algorithm is very simple to use as it only requires a coarse depth map of the scene and the locations and properties of the light sources. We have rendered rain in a wide range of scenarios and the results show that our physically-based rain streak model greatly enhances the visual realism of rendered rain.
Nucleotide excision repair genes are expressed at low levels and are not detectably inducible in Caenorhabditis elegans somatic tissues, but their function is required for normal adult life after UVC exposure.

We performed experiments to characterize the inducibility of nucleotide excision repair (NER) in Caenorhabditis elegans , and to examine global gene expression in NER-deficient and -proficient strains as well as germline vs. somatic tissues, with and without genotoxic stress. We also carried out experiments to elucidate the importance of NER in the adult life of C. elegans under genotoxin-stressed and control conditions. Adult lifespan was not detectably different between wild-type and NER-deficient xpa - 1 nematodes under control conditions. However, exposure to 6 J/m 2 /day of ultraviolet C radiation (UVC) decreased lifespan in xpa - 1 nematodes more than a dose of 100 J/m 2 /day in wild-type. Similar differential sensitivities were observed for adult size and feeding. Remarkably, global gene expression was nearly identical in young adult wild-type and xpa - 1 nematodes, both in control conditions and 3 h after exposure to 50 J/m 2 UVC. Neither NER genes nor repair activity were detectably inducible in young adults that lacked germ cells and developing embryos ( glp - 1 strain). However, expression levels of dozens of NER and other DNA damage response genes were much (5–30-fold) lower in adults lacking germ cells and developing embryos, suggesting that somatic and post-mitotic cells have a much lower DNA repair ability. Finally, we describe a refinement of our DNA damage assay that allows damage measurement in single nematodes.
A comparison of representations for the prediction of ground-level ozone concentration

This work presents a comparison of methods to predict ground-level ozone to highlight differences in the ability of the algorithms and to compare their performance to an established signal to noise based prediction method. Existing data related to weather conditions and ground-level ozone was divided into a training set and a test set. Three algorithms were trained using the training set to create predictors, which were then analyzed with the test set, and then compared to the Taguchi Method to determine performance. It was found that the newly introduced R-LCS performed well on this problem, predictors using the Taguchi method had a smaller deviation from actual results. This indicates an additional factor other than the level of correlation in the data that dictates how well these predictors perform on classification problems.
Regulation of Tn5 transposition in Salmonella typhimurium.

Abstract The drug-resistance element Tn5 transposes with high frequency immediately after entry into a cell. Establishment of Tn5 within a cell results in a decrease in this transposition frequency. This phenomenon resembles "zygotic induction" of repressible operons and prophages. Evidence is presented that Tn5 transposition is under negative control by a factor encoded within the element itself. Established Tn5 elements (that contain point mutations inactivating the resistance gene) are able to inhibit transposition of an incoming Tn5 element by a factor of 12- to 70-fold. Several deletion derivatives of Tn5 lack the ability to inhibit transposition.
Mechanisms of thrombin-stimulated cell division.

Addition of highly purified thrombin t o cultures of several kinds of nondividing fibroblasts brings about cell division. This stimulation occurs in serum-free medium, permitting studies on its mechanism under chemically defined conditions. Previous studies have shown that action of thrombin a t the cell surface is sufficient to cause cell division and that the proteolytic activity of thrombin is required for its mitogenic effect. These results prompted experiments which showed that there is a cell surface receptor for thrombin and that thrombin must hind to its receptor and cleave it to stimulate cell division. Some of the thrombin that hinds to its receptors becomes attached to them by a linkage that appears to be covalent. However, it is presently unknown whether this direct thrombin receptor complex plays a role in the stimulation. These results raise a number of question that should be explored in future studies. They also provide a foundation on which to build hypotheses about tentative molecular mechanisms that might be involved in the stimulation. Knowledge that thrombin must cleave its receptor to bring about cell division suggests two alternative mechanisms for stimulation by proteolysis. In one the receptor is a negative effector which prevents cell division when it is intact, but not after it has been cleaved. Alternatively, a fragment of the receptor could be a positive effector. In this mechanism, proteolysis by thrombin would produce a specific receptor fragment which brings about cell proliferation. If every protease which cleaves the receptor also stimulates cell division, the receptor is probably a negative effector. In contrast, if certain proteases cleave the receptor but do not stimulate the cells, a fragment of the receptor is likely a positive effector. With negative regulation by the receptor, the controlling events would occur before proteolysis of it, and it might be possible to find putative regulatory molecules by identification of nearest neighbors of the receptor. This should be possible by using bifunctional crosslinking reagents. If a fragment of the thrombin receptor turns out to be a positive effector, it should be possible to identify and study fragments by analyzing the metabolic fate of the receptor. Techniques are now available for this kind of analysis and it should also be possible to determine whether receptor fragments remain in the membrane or whether they are translocated to specific sites within the cell. A critical question to be asked is which of these events and interactions involving the thrombin receptor are necessary for stimulation of cell division. It now appears that the best way to answer this question is to examine these events in a large number of cloned cell populations that are responsive or unresponsive to the mitogenic action of thrombin. If a thrombin-mediated event occurs in all responsive clones but is altered or absent in sonie unresponsive clones, it is probably necessary for stimulation of cell division.
Characterization of Adsorption of Sodium Dodecyl Sulfate on Charge-Regulated Substrates by Atomic Force Microscopy Force Measurements

The adsorption of sodium dodecyl sulfate (SDS) on gold surfaces covered with self-assembled monolayers (SAMs) of thiols made with either hexadecyl mercaptan or 2-aminoethanethiol hydrochloride was investigated by probing the surface charge. This was accomplished by determining the force between a modified (with a negatively charged silica sphere) tip of an atomic force microscope and the surface as SDS was adsorbed. The ionic nature of aqueous SDS solutions and the critical micelle concentration (cmc) in deionized water were determined by measuring the sudden change in diffuse double-layer thickness on micelle formation. The interaction between a silica probe and an initially positively charged gold substrate with a 2-aminoethanethiol layer was a strong function of SDS concentration. The phenomenon of surface charge reversal (where the amount of negative SDS equals the cationic surface charge) was directly observed at an SDS concentration of about 1/1000 cmc. The surface electrostatic potentials of the su...
Simulating the Effect of Aerobic Biodegradation on Soil Vapor Intrusion into Buildings: Influence of Degradation Rate, Source Concentration, and Depth

Steady-state vapor intrusion scenarios involving aerobically biodegradable chemicals are studied using a three-dimensional multicomponent numerical model. In these scenarios, sources of aerobically biodegradable chemical vapors are placed at depths of 1−14 m beneath a 10 m × 10 m basement or slab-on-grade construction building, and the simultaneous transport and reaction of hydrocarbon and oxygen vapors are simulated. The results are presented as Johnson and Ettinger attenuation factors α (predicted indoor air hydrocarbon concentration/source vapor concentration), and normalized contour plots of hydrocarbon and oxygen concentrations. In addition to varying the vapor source depth, the effects of source concentration (2−200 mg chemical/L vapor) and oxygen-limited first-order reaction rates (0.018−1.8 h-1) are studied. Hydrocarbon inputs were specific to benzene, although the relevant properties are similar to those for a range of hydrocarbons of interest. Overall, the results suggest that aerobic biodegrada...
Behavior and Attention in LD Children

The performance of 90 learning disabled (LD) children on two measures of behavior and attentional skills was examined: (a) the Revised Behavior Problem Checklist (RBPC, Quay & Peterson, 1987) is a parent-rated multivariate behavior scale; and (b) the Continuous Performance Test (CPT, Lindgren & Lyon, 1983) is a laboratory vigilance / impulsivity measure. As a group, the LD subjects exceeded normative standards on every measure of both scales. However, when the data were examined individually, approximately 30% of the children accounted for the majority of behavioral problems. The most common difficulties were noted on attention, cognitive processing, anxiety, and excessive motor activity.
Extraslice spin tagging (EST) magnetic resonance imaging for the determination of perfusion.

A new magnetic resonance technique to measure perfusion is described in detail. The means by which this is done is to invert all the spins in the radiofrequency RF coil with a non-spatially selective pulse and immediately re-invert the spins in the imaging plane. The net effect is that the spins in the imaging plane experience minimal perturbation of their magnetization while the spins outside the plane (extraslice) are inverted, or tagged. Tagged spins that flow into the imaging plane before image data are acquired decrease the signal intensity in the imaging plane when compared with an image in which the inflowing spins are not tagged. This decrease in signal can be used to calculate the number of spins that have flowed into the imaging plane, i.e., can be used to calculate the perfusion in mL · 100 gtissue−1 · min−1. The extraslice spin tagging (EST) magnetization preparation period was coupled with a fast imaging sequence to obtain perfusion maps for normal volunteers. J. Magn. Reson. Imaging 1999;9:146–150 © 1999 Wiley-Liss, Inc.
Studies on the biochemical basis of oxygen toxicity.

Abstract The toxic effects of high pressure oxygen on the isolated toad urinary bladder have been studied. Sodium transport in this system is reversibly inhibited by high pressure O 2 . This inhibition is potentiated by adrenal steroid hormones, and occurs despite both increased glycolytic and Kreb's cycle flux and tissue ATP content. High pressure O 2 leads to increased pyruvate/lactate and pyruvate/malate redox couples, as well as to a decrease in the weight percentage of phospholipid long-chain unsaturated fatty acids and [2- 14 C]pyruvate incorporation into tissue lipid. During recovery from high pressure O 2 treatment, [2- 14 C]Pyruvate incorporation into lipid is increased and the weight percentage of long-chain unsaturated fatty acids increases. These data indicate that high pressure O 2 poisoning in this tissue does not result from an inhibition of carbohydrate metabolism, but may result from the formation of toxic lipid peroxides.
Studies on the iodinated surface membrane proteins and concanavalin A agglutination of transformed Syrian hamster cells.

Abstract Chemically transformed Syrian hamster cells exhibit marked agglutination in the presence of the plant lectin, concanavalin A. In this report, we describe conditions which can alter this concanavalin A agglutinability, and compare the surface proteins from transformed cells which express different degrees of agglutinability. Lactoperoxidase-catalyzed iodination of tertiary Syrian hamster cells reveals the major iodinatable protein to be approximately 220 000 daltons. The transformed Syrian hamster cells do not contain this protein in an iodinatable form. Analyses of the transformed cells grown under conditions which decrease the concanavalin A agglutinability do not demonstrate any iodination of the 220 000 mol. wt. protein. These results depict the effects of growth and dibutyryl cyclic AMP on the iodinatable cell surface proteins of transformed cells and indicate that the absence of the 1–220 000 mol. wt. protein is probably not a major determinant of concanavalin A agglutination.
Sensitivity analysis for lexicographic ordering in radiation therapy treatment planning

Purpose: To introduce a method to efficiently identify and calculate meaningful tradeoffs between criteria in an interactive IMRT treatment planning procedure. The method provides a systematic approach to developing high-quality radiation therapy treatment plans. Methods: Treatment planners consider numerous dosimetric criteria of varying importance that, when optimized simultaneously through multicriteria optimization, yield a Pareto frontier which represents the set of Pareto-optimal treatment plans. However, generating and navigating this frontier is a time-consuming, nontrivial process. A lexicographic ordering (LO) approach to IMRT uses a physician’s criteria preferences to partition the treatment planning decisions into a multistage treatment planning model. Because the relative importance of criteria optimized in the different stages may not necessarily constitute a strict prioritization, the authors introduce an interactive process, sensitivity analysis in lexicographic ordering (SALO), to allow the treatment planner control over the relative sequential-stage tradeoffs. By allowing this flexibility within a structured process, SALO implicitly restricts attention to and allows exploration of a subset of the Pareto efficient frontier that the physicians have deemed most important. Results: Improvements to treatment plans over a LO approach were found by implementing the SALO procedure on a brain case and a prostate case. In each stage, a physician assessed the tradeoff between previous stage and current stage criteria. The SALO method provided critical tradeoff information through curves approximating the relationship between criteria, which allowed the physician to determine the most desirable treatment plan. Conclusions: The SALO procedure provides treatment planners with a directed, systematic process to treatment plan selection. By following a physician’s prioritization, the treatment planner can avoid wasting effort considering clinically inferior treatment plans. The planner is guided by criteria importance, but given the information necessary to accurately adjust the relative importance at each stage. Through these attributes, the SALO procedure delivers an approach well balanced between efficiency and flexibility.
The effects of hypermedia knowledge and learning style on the construction of group concept maps

Abstract This study involved 20 research participants who created group concept maps on the term “hypermedia.” The purpose of the study was to determine whether groups, membership of which was based on a mixture of learning styles or a mixture of hypermedia knowledge, constructed concept maps that differed in terms of number of concepts, number of nodes, number of links, number of bidirectional links, number of multiple concept nodes, number of nodes with multiple links, and varying levels of hierarchical relationships. It was found that the group comprised of two convergers, one assimilator, and one diverger, all of whom had a high level of hypermedia knowledge, was the most productive. Of the 11 measures, they produced the most for 7 of them. We were also interested in determining the interactive dynamics that either learning style or hypermedia knowledge played as the participants constructed their group concept maps. We audiotaped their interactions and categorized their comments and actions within the learning style traits associated with being either a converger, a diverger, an assimilator, or an accommodator. Learning style seemed to explain the types of interactions more than hypermedia knowledge did.
Sample size calculation for a hypothesis test.

In this issue of JAMA, Koegelenberg et al1 report the results of a randomized clinical trial (RCT) that investigated whether treatment with a nicotine patch in addition to varenicline produced higher rates of smoking abstinence than varenicline alone. The primary results were positive; that is, patients receiving the combination therapy were more likely to achieve continuous abstinence at 12 weeks than patients receiving varenicline alone. The absolute difference in the abstinence rate was estimated to be approximately 14%, which was statistically significant at level α = .05.
Effect of Dimethylbenzyldesmethylrifampicin (DMB) on Chemically Induced Mammary Tumours in Rats

SEVERAL derivatives of rifamycin SV have been shown to inhibit virus-induced transformation in tissue culture. Transformation of chick fibroblasts induced by Rous sarcoma virus (RSV) is inhibited by rifampicin at levels of 20–60 µg/ml.1–3, and the transformation of Balb/3T3 cells induced by Moloney sarcoma virus (MSV) is inhibited more than 90% by dimethyl-benzyldesmethylrifampicin (DMB) at levels of 6 µg/ml.4,5.
Forecasting 3-D fish movement behavior using a Eulerian-Lagrangian-agent method (ELAM)

Abstract We describe a Eulerian–Lagrangian–agent method (ELAM) for mechanistically decoding and forecasting 3-D movement patterns of individual fish responding to abiotic stimuli. A ELAM model is an individual-based model (IBM) coupling a (1) Eulerian framework to govern the physical, hydrodynamic, and water quality domains, (2) Lagrangian framework to govern the sensory perception and movement trajectories of individual fish, and (3) agent framework to govern the behavior decisions of individuals. The resulting ELAM framework is well suited for describing large-scale patterns in hydrodynamics and water quality as well as the much smaller scales at which individual fish make movement decisions. This ability of ELAM models to simultaneously handle dynamics at multiple scales allows them to realistically represent fish movements within aquatic systems. We introduce ELAMs with an application to aid in the design and operation of fish passage systems in the Pacific Northwest, USA. Individual virtual fish make behavior decisions about every 2.0 s. These are sub-meter to meter-scale movements based on hydrodynamic stimuli obtained from a hydraulic model. Movement rules and behavior coefficients are systematically adjusted until the virtual fish movements approximate the observed fish. The ELAM model introduced in this paper is called the Numerical Fish Surrogate. It facilitated the development of a mechanistic biological-based hypothesis describing observed 3-D movement and passage response of downstream migrating juvenile salmon at 3 hydropower dams on 2 rivers with a total of 20 different structural and operational configurations. The Numerical Fish Surrogate is presently used by the U.S. Army Corps of Engineers and public utility districts during project planning and design to forecast juvenile salmon movement and passage response to alternative bypass structures.
Hemodynamic effects of aerosol propellants. III. Vascular resistance in the canine hind limb.

Abstract The question as to whether or not the hypotension observed as part of the effect of trichlorofluoromethane (FC 11), dichlorofluoromethane (FC 12), dichlorotetrafluoroethane (FC 114) and methyl chloroform was due to a vasodepressor component of action, in addition to the previously documented depression in myocardial contractile force, was answered by testing these agents in an anesthetized dog preparation in which one hind limb was perfused at constant flow through the femoral artery. 5% FC 11, 20% FC 12 and 20% FC 114 decreased vascular resistance of the perfused limb, as reflected by decrease in mean femoral arterial perfusion pressure, in vagotomized but not in intact preparations. Methyl chloroform decreased vascular resistance even in intact preparations. Spontaneous blood flow in the intact femoral artery decreased following FC 11 and methyl chloroform administration in vagotomized preparations and was associated with marked decrease in mean aortic pressure. Blockade of alpha and beta adrenergic receptors with phentolamine and propranolol in the vagotomized preparation had no modifying influence of the effect of FC 11 and methyl chloroform. It may be concluded from this study that FC 11, FC 12 and FC 114 exhibit a vasodepressor activity on skeletal muscle vascular bed which is readily overcome by the hypotension-induced activation of the sympathetic system but which becomes evident when reflex activity is presented by vagotomy. Methyl chloroform exhibits a vasodepressor effect even in intact preparations probably because of concomitant depression of reflex activity through its general anesthetic action. A decrease in spontaneous femoral blood flow following FC 11 and methyl chloroform administration is referable to the accompanying severe hypotension notwithstanding concomitant vascular relaxation. Neither FC 11 nor methyl chloroform directly liberate catecholamines from their sites of storage.
Influence of shock loading on the structure/property response of Ti-48Al-2Cr-2Nb and Ti-24Al-11Nb

Une attention croissante est portee sur les intermetalliques avec les applications qui necessitent des materiaux a avoir un resultant final potentiellement grand, par exemple dans les turbines a gaz. Tandis que la reponse d'une gamme d'intermetalliques deformes dans des conditions quasi-statiques recoit une etude scientifique et d'ingenieur, une exploitation augmentee des intermetalliques deformes en dynamique necessite une comprehension des effets de grande vitesse de deformation/onde de choc. L'influence sur la structure lors d'un chargement du choc des alliages Ti-48Al-2Cr-2Nb et Ti-24Al-11Nb est presentee. La reponse des deux intermetalliques charges indique que la deformation dans des conditions dynamiques est controlee par un mecanisme Peierls
Molecular hydrodynamics of inhomogeneous systems: The origin of slip boundary conditions

Abstract Molecular hydrodynamic equations derived by linear response theory for inhomogeneous systems are investigated in two extreme cases: a simple fluid in a gravitational field (an example of a long-range inhomogeneity), and a simple fluid in the presence of a rigid flat wall described by an infinite potential step (an example of a short-range inhomogeneity). In both cases the phenomenological equations result when the molecular equations are smoothed over a length which is large compared to the correlation lenght. For these systems the local equilibrium assumption is shown to be valid. In addition it is shown how the usual slip boundary conditions arise as a consequence of the interaction which causes the short-range inhomogeneity.
Applying the Socio-ecological Model to Improving Fruit and Vegetable Intake Among Low-Income African Americans

Despite the growing body of literature that provides evidence of the health benefits of a diet high in fruits and vegetables, most Americans eat much less than the recommended amounts of this food group. Among those who are least likely to meet the USDA guidelines for the recommended daily servings of fruits and vegetables are non-Hispanic Blacks and individuals with lower incomes. The purpose of this literature review is to examine the dietary behaviors, focusing on fruit and vegetable intake, of low-income African Americans from a socio-ecological perspective, and to offer rationale for and guidance on integrating socio-ecological concepts into health promoting programs intended to improve dietary behaviors among this population. Based on the 12 descriptive studies retrieved in the review, dietary behaviors and fruit and vegetable intake among African Americans are the result of a complex interplay of personal, cultural, and environmental factors that can be categorized and described using the five levels of influence conceptualized by the socio-ecological model: Intrapersonal level (taste preferences, habits, and nutritional knowledge and skills), Interpersonal level/social environment (processes whereby culture, social traditions, and role expectations impact eating practices; and patterns within peer groups, friends and family), and Organizational, Community, and Public Policy levels/physical environment (environmental factors that affect food access and availability). The socio-ecological model provides a useful framework for achieving a better understanding of the multiple factors and barriers that impact dietary behaviors, and therefore can provide guidance for developing culturally appropriate and sensitive intervention strategies for African Americans. It is an integrative framework that shows great promise in moving the field closer to attaining the goal of improving dietary behaviors and nutritional status among African Americans.
The understanding of nuclear structure through Mössbauer experiments

Mossbauer's discovery vitalized the study of hyperfine interactions on nuclear states. The technique has been used to measure the electromagnetic moments of scores of nuclear levels and the results, especially on rotational states, have been important to our understanding of nuclear structure. Equally signicant for nuclear physics has been the deep insight which Mossbauer studies have given us of the hyperfine interaction itself; using that knowledge, and a variety of techniques, the measurements of nuclear magnetic moments are now reliable and routine.
Social foraging by honeybees: how colonies allocate foragers among patches of flowers

To understand how a colony of honeybees keeps its forager force focussed on rich sources of food, and analysis was made of how the individual foragers within a colony decide to abandon or continue working (and perhaps even recruit to) patches of flowers. A nectar forager grades her behavior toward a patch in response to both the nectar intake rate of her colony and the quality of her patch. This results in the threshold in patch quality for acceptance of a patch being higher when the colonial intake rate of nectar is high than when it is low. Thus colonies can adjust their patch selectivity so that they focus on rich sources when forage is abundant, but spread their workers among a wider range of sources when forage is scarce. Foragers assess their colony's rate of nectar intake while in the nest, unloading nectar to receiver bees. The ease of unloading varies inversely with the colonial intake rate of nectar. Foragers assess patch quality while in the field, collecting nectar. By grading their behavior steeply in relation to such patch variables as distance from the nest and nectar sweetness, foragers give their colony high sensitivity to differences in profitability among patches. When a patch's quality declines, its foragers reduce their rate of visits to the patch. This diminishes the flow of nectar from the poor patch which in turn stimulates recruitment to rich patches. Thus a colony can swiftly redistribute its forager force following changes in the spatial distribution of rich food sources. The fundamental currency of nectar patch quality is not net rate of energy intake, (Gain-Cost)/Time, but may be net energy efficiency, (Gain-Cost)/Cost.