cssi/SciSciGPT-SciSciNet huggingface dataset:
Controls on the stable carbon isotopic composition of biogenic methane produced in a tidal freshwater estaurine sediment

Abstract The δ13C value of methane in sediments from a tidal freshwater site in the White Oak River Estuary, North Carolina, exhibited a relatively small, but consistent, seasonal variation (∼3‰) with isotopically heavier values occurring during the warmer months (−66.1‰ summer, −69.2‰ winter). These isotopic shifts could have resulted from changes in: (1) isotopic compositions of precursor molecules; (2) kinetic isotope effects associated with methane production; or (3) pathways of methane production. Methane production rate and isotopic data from sediment incubation experiments and field measurements were used to determine the relative contributions of these factors to the observed seasonal variations. Although changes in δ13C values of biogenic methane are typically thought to result from changes in pathways of methane production, this study showed that a significant amount (36 ± 22%) of the seasonal variations between the δ13C value of methane produced in sediment incubation experiments could be attributed to changes in the δ13C value of the ΣCO2 pool. This was due to increased methane production rates and removal of 12CO2 with increasing temperature, a prevalent feature of methanogenic systems that may account for some of the frequently observed 13C enrichment in methane during warmer months. Combining the change in the δ13C value of the ΣCO2 pool with temperature-controlled changes in fractionation (α) resulting from kinetic isotope effects accounted for (53 ± 22%) of the 13C enrichment observed during summer sediment incubation experiments. Although large pathway changes were not observed in sediment incubation experiments, the remaining differences in δ13C values could have resulted from smaller, undetectable changes in the percentage of methane production from acetate (∼14%) and/or a shift in the δ13C values of methane produced from acetate (∼4‰).
Teaching an old dog new tricks: SINEs of canine genomic diversity

With >400 recognized breeds worldwide and a recently completed draft genomic sequence, the dog has emerged as a model organism of choice for the genetic dissection of morphological traits and diseases (1–3). Of great interest is the fact that a number of disorders in purebred dogs are also of human medical relevance (1, 2). In this context, the study by Clark et al. (4) in this issue of PNAS is exciting because of its implications on morphological, medical, and evolutionary grounds. Indeed, the authors have discovered a mutation in the dog SILV gene that is responsible for merle, a color patterning in the coat of various canine breeds. Strikingly, merle dogs exhibit auditory and ophthalmologic abnormalities similar to those observed for the human auditory-pigmentation disorder Waardenburg syndrome, which accounts for 2–5% of all human cases of congenital deafness (5). The different dog breeds were established within the past few centuries from small numbers of founding individuals. As a consequence, linkage disequilibrium within the genome extends over at least 50-fold greater distances in dogs as compared to humans (3). Taking advantage of this feature of the dog genome, Clark et al. (4) carried out a whole-genome scan using the Shetland Sheepdog and were able to map the merle locus to the dog homologue of human chromosome 12q13. Characterization of the pigment gene SILV (6) located in this region revealed the presence of a short interspersed element (SINE) inserted at an intron/exon boundary that segregates with the merle phenotype (4). SINEs are “jumping genes” belonging to the retrotransposon class of mobile elements that propagate in their host genomes via a “copy and paste” mechanism (7–11). Because only a small fraction of mammalian genomes is functional, most retrotransposon insertions occur in genomic regions where they essentially induce …
Interaction of neomycin with ribosomes and ribosomal ribonucleic acid.

Neomycin binds ribosomes and ribosomal ribonucleic acid (rRNA) in vivo and in vitro producing changes detectable by increases in gel electrophoretic mobility. These changes were observed in gels that contain ethylenediaminetetraacetic acid or no added magnesium ion. The progressive increase in gel electrophoretic mobility with increasing antibiotic concentrations suggests that neomycin is binding at multiple sites on RNA. The binding was reversible but sufficiently stable to survive dialysis and electrophoresis. It is proposed that bound neomycin stabilizes the ribosome and RNA structures, restricting the unfolding of the particles during electrophoresis and thus allowing for a more rapid migration in the gel. Gentamicin produced an effect similar to that of neomycin. Paromomycin, differing from neomycin by only one amino group, had considerably less effect on ribosome and rRNA mobilities. The binding of neomycin to rRNA improved the linearity of the plot of log molecular weight versus mobility and thus may be of benefit in providing a more accurate estimation of molecular weights of large RNAs. Images
Service-Learning in Early Childhood Teacher Education: Using Service to Put Meaning Back into Learning.

Abstract Service-learning is defined as a teaching/learning method that connects meaningful community service with academic learning, personal growth, and civic responsibility. In this study, conducted at an American University, we describe a cascading model of integrating early childhood teacher education and service-learning for preservice teachers who then implemented the combined model in their field classrooms with young children. Examples of the projects from the two cohorts of 25 and 26 undergraduate students are provided. We demonstrate that service-learning projects provide an instructional avenue for preservice students to teach in an integrated and/or experiential manner in their field classrooms and discuss why service-learning is an appropriate and meaningful strategy to use with preservice teachers and children.
Interpretation of the carbon Auger line shapes for the adsorption and decomposition of ethylene on Ni(100)

The CKVV Auger line shapes of ethylene chemisorbed on Ni(100) at 100, 250, 300 and 600 K are reported and consistently interpreted. These line shapes are representative of π-bonded ethylene (C2H4(a)) at 100 K, σ-bonded vinyl (CHCH2(a)) at 250 K, a mixture of ethynyl (CCH(a)), methylidyne (CH(a)) and di-σ-bonded acetylene (HCCH(a)) at 300 K, and carbidic carbon (C(a)) at 600 K on the surface. The Auger line shape of graphitic carbon adlayers on Ni is also interpreted. The line shapes are found to consist of adsorbate-adsorbate, adsorbate-substrate, and substrate-substrate components, which are denoted by the final location of the two holes created by the Auger process. The adsorbate-adsorbate component, for the C2 chemisorbed species, reflects primarily the valence density of states of ethylene and shows negligible hole-hole correlation effects due to electron transfer from the metal. This is in contrast to the graphitic adlayer where the adsorbate-adsorbate component has the same line shape as bulk graphite and exhibits significant correlation effects. The adsorbate-substrate and substrate-substrate components seen in all of the line shapes directly reflect the adsorbate-substrate π or σ bonding character, and the extent of screening via charge transfer from the metal to the core excited adsorbate.
Ethnic Differences in Alcohol Sensitivity

Japanese, Taiwanese, and Koreans, after drinking amounts of alcohol that have no detectable effect on Caucasoids, respond with a marked facial flushing and mild to moderate symptoms of intoxication. Group differences are present at birth, and are probably related to variations in autonomic reactivity.
MYC as a regulator of ribosome biogenesis and protein synthesis

Recently, MYC has been shown to serve as a direct regulator of ribosome biogenesis and therefore coordinates protein synthesis. Could the regulation of ribosome biogenesis by MYC be necessary for its role in tumorigenesis? MYC regulates the transcription of thousands of genes required to coordinate a range of cellular processes, including those essential for proliferation, growth, differentiation, apoptosis and self-renewal. Recently, MYC has also been shown to serve as a direct regulator of ribosome biogenesis. MYC coordinates protein synthesis through the transcriptional control of RNA and protein components of ribosomes, and of gene products required for the processing of ribosomal RNA, the nuclear export of ribosomal subunits and the initiation of mRNA translation. We discuss how the modulation of ribosome biogenesis by MYC may be essential to its physiological functions as well as its pathological role in tumorigenesis.
Lymphocyte-induced production of prostaglandin E2 by tumor cells in vitro: Requirements for direct contact and lymphocyte viability

Abstract The production of prostaglandin E 2 by tumor cell lines in response to exposure to purified lymphocytes has prompted the suggestion that this phenomenon may represent a defense mechanism whereby tumors may subvert an immune response mounted against them. To further characterize this phenomenon, cell lines derived from carcinogen-induced bladder tumors and embryo fibroblasts in Fischer rats were incubated with purified lymphocytes from peripheral blood, spleen, thymus, and lymph nodes from Fischer rats under a variety of conditions, and the amount of prostaglandin E 2 (PGE 2 ) production was determined by radioimmunoassay. Increased numbers of blood or splenic lymphocytes were associated with the induction of increased levels of PGE 2 production by the tumor cells. However, no prostaglandin was produced by the tumor cells after exposure to thymus or lymph node lymphocytes. Irradiation of lymphocytes prior to exposure to the tumor cells led to lower levels of PGE 2 production by the tumors, as did sonication of the lymphocyte preparations prior to addition to the tumor monolayers. Separation of lymphocytes from direct contact with the tumor cells resulted in less PGE 2 production by the tumor cell lines; however, when these lymphocytes were later layered onto fresh tumor cell monolayers, PGE 2 production occurred. Results in the present study suggest that direct contact between intact, viable, functionally active lymphocytes and tumor cells is necessary for tumor cell prostaglandin production to occur. Moreover, PGE 2 production only appears to occur in response to exposure to particular populations of lymphocytes, and this may correlate with the number of specific effector or attacker lymphocytes that are present. This specificity of response to effector cell challenge may be important in probing the defense mechanisms tumor cells may have to lymphocyte challenge, as well as in gauging the efficacy of a particular cellular immune response as it may be regulated both by cells involved in effecting this response as well as by the targets in lymphocyte/tumor cell interactions.
Coming out in class: Disclosure of sexual orientation and teaching evaluations

A lesbian assistant professor of counseling psychology disclosed her sexual orientation during lectures to 2 sections of an undergraduate course and did not disclose in 2 comparable sections of the same course. Group differences in means and variances of teaching evaluations were examined for possible student bias. No evidence of sexual orientation bias was found.
The Limits of Legal Realism as Biography

Among the greatest Supreme Court Justices, there are a few whose lives and achievements would clearly have warranted a biographer's attention even if they had never ascended to the high bench. Thurgood Marshall, Brandeis, Frankfurter, Holmes, Cardozo, and Hughes all belong clearly in that camp. The lives of John Marshall and Earl Warren would also have made a "good read." There is no reason, however, to think the same of William J. Brennan, whom journalist Kim Isaac Eisler identifies as "the most influential Justice of the twentieth century" (at 13). Without the Court, Justice Brennan's career would likely have been distinguished but unexceptional. The life of a New Jersey federal district court judge with a first-rate corporate law practice behind him seems an unlikely literary temptation. But the ordinariness of Justice Brennan's pre-Court life poses challenges also for a biographer looking back on his Supreme Court career. One reason why the entire life of a Thurgood Marshall sustains a satisfying narrative is that his judicial and pre-judicial careers seem of a piece. I do not mean this in a reductionist way, as if to discount the entire judicial contribution of a Thurgood Marshall as simply the reflexive thinking of an activist civil rights lawyer. I mean only that there are clear and compelling connections between Marshall's judicial and extrajudicial lives. You can tell, as the saying goes, "where he was coming from." Especially for journalists, that makes a good story.
Knowledge representation for image content analysis in medical image database

The object-oriented knowledge representation is considered as a natural and effective approach. Nevertheless, the use of object-oriented within complex image analysis has not undergone a rapid growth as it happened in other fields. We argue that one of the major problems comes from the difficulty of conceiving a comprehensive framework for coping with the different abstraction levels and the vision task operations. With the goal to overcome such a drawback, we present a new knowledge model for medical image content analysis based on the object-oriented paradigm. The new model abstracts common model for medical image content analysis based on the object-oriented paradigm. The new model abstracts common properties from different types of medical images by using three attribute parts: description, component, and semantic graph, and also specifies its actions to schedule the detection procedure, properly deform the shape of model components to match the corresponding anatomies in images, select the best match candidates, and verify combination graphs from detected candidates with the semantic graph defined in the model. The performance of the proposed model has been tested on pelvis digital radiographs. Initial results are encouraging.
Spatially resolved heavy ion induced desorption mass spectrometry

Heavy ion induced plasma desorption mass spectrometry was used with a micro-beam in a scanning mode. A 10 μm diameter 84 MeV 84Kr+7 beam was used for the desorption. A target of NaCl and KCl microcrystals was scanned relative to the beam. Mass spectra were obtained as a function of position on the sample.
Plant-derived triterpenoid sweetness inhibitors.

Considerable recent attention has been focused on naturally occurring compounds with taste-modifying activity, which are of potential use in both dietary sweetness management and in gaining a better understanding of the sweet taste sensation. This review summarizes information on the phytochemistry and biological activity of more than 40 triterpenoid sweetness inhibitors that have been isolated from the leaves of three medicinal plants, namely, Gymnema sylvestre R.Br. (Asclepiadaceae), Ziziphus jujuba P. Miller (Rhamnaceae), and Hovenia dulcis Thunb. (Rhamnaceae).
Measuring basic needs satisfaction: Evaluating previous research and conducting new psychometric evaluations of the Basic Needs Satisfaction in General Scale

Self-Determination Theory specifies the existence of three basic psychological needs: autonomy, competence, and relatedness. The current set of studies (a) provides a narrative review of past research on the Basic Needs Satisfaction in General Scale, (b) examines its dimensionality which has been assumed but not empirically studied, and (c) gathers external validity evidence. Confirmatory factor analysis was used to test the existence of a one- and a three-factor solution; neither model fit the data. After patterns of misfit were examined across three independent samples, a reduced, 16-item three-factor model with a negative-worded method effect was championed. External validity evidence, collected by examining the differential relationships between the three needs and measures of well-being and worry, supported the distinctiveness of the three needs. Although the results are promising, future research is needed to examine the generalizability of the psychometric properties of the modified scale.
Saturation spectroscopy and resonant degenerate four-wave mixing in Hg at 546.1 nm

Doppler-free saturation spectroscopy performed in an rf discharge in mercury vapor has made it possible to identify clearly all the central components of the 546.1-nm transition.Resonant degenerate four-wave mixing has also been observed in this system at this wavelength.
Intelligent packaging for the future smart kitchen

This paper introduces the concepts of intelligent packaging and the future smart kitchen. A case study is presented to illustrate the important role of intelligent packaging in providing the consumer with higher food quality, better convenience and safety in cooking packaged foods using a microwave/convective oven. Copyright © 2000 John Wiley & Sons, Ltd.
Critical care of the burn patient

Summary Comprehensive care of burn patients requires attention to details throughout the acute phase of the patient's recovery to maximize survival. Team efforts by surgeons, anesthesiologists, nurses, scientists, and a vast array of therapists are making productive and social lives possible for many of these burn victims. Overall, advances in the treatment of initial injuries and their complications as wlll as new surgical techniques for closing wounds and reducing, scar tissue have increased burn patient's chances, not only of survival but also of recovery and readjustment into society. However, many problems still need to be solved, such as inhalation injury hypermetabolism with muscle wasting, and severe burn scarring. New therapies, such as percussive ventilators, growth hormone, and newer methods of covering wounds, will ultimately lead to further improvements in survival and functional outcome.
Learning to ask, listen, and analyse: using structured interviewing assignments to develop reflection in preservice science teachers

In this paper we report on work done with preservice science teachers in a course that aims to increase students’ abilities to reflect on their own pedagogical understandings. The course is part of a teacher education programme that embraces a constructivist philosophy and hopes to generate teachers able to help their future pupils learn science content and processes with greater depth of understanding than is too typically the case. Our paper begins with a description of the context of the course and a clarification of the notion of reflection. We move on to consider the interviewing activities that are designed to increase students’ understanding and reflection. In presenting the results of these activities we identify not only the kinds of understandings students developed but also what we as teachers learned and discuss some of the problems and dilemmas encountered in teaching this course.
A Critical Appraisal of Sara Lawrence-Lightfoot's Portraiture as a Method of Educational Research

Portraiture is a creative qualitative approach to engaging in research of leaders and groups in action and in telling the stories of individuals in life. It was first employed to great effect in Sara Lawrence-Lightfoot's 1983 AERA award-winning book, The Good High School. In an effort to expand and explain the application of portraiture as a method of scientific research, Lightfoot co- authored a second book with Jessica Hoffmann Davis entitled The Art and Science of Portraiture, released in 1997. This article critically examines the assumptions and methods of portraiture. It questions the authority of the portraitist in arbitrarily and unilaterally creating portraits, pointing out there is no external, independent referent for ascertaining the truth-telling capacity of the portraitist because the definition of truth is circular. Further more, the objective of portraiture to capture the "'essence" of the subject is implicitly a quest for a foundationaI and stable truth, which in turn requires the portrait...
Pre-school children's first encounter with a robot

In this work, we investigate pre-school age children’s attitudes and beliefs about robots, and how these are affected by interacting with a physical robot, as shown in Fig.1.
Intraoral findings in patients with psoriasis with a special reference to ectopic geographic tongue (erythema circinata)

Abstract One hundred patients with a severe relapse of cutaneous psoriasis underwent a full intraoral examination. Nineteen patients had “ectopic geographic tongue” of the palate or buccal mucosa, and there appeared to be an increased incidence of periodontal disease. All other findings were within the normal range. HLA antigen studies of eight patients were carried out and showed an increased incidence of DR7.
Doppler frequency estimation with wavelets and neural networks

In this paper we apply the continuous wavelet transform, along with multilayer feedforward neural networks, to the estimation of time-dependent radar doppler frequency. The wavelet transform employs the real-valued Morlet wavelet, which is well matched to the doppler signals of interest. The neural networks are trained with the Levenberg-Marquardt rule, which is much faster than purely gradient-descent learning algorithms such as back propagation. We also apply Donoho's wavelet denoising with the novel super-Haar wavelet to improve performance for noisy signals. The techniques are applied to the problem of radar proximity fuzing.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
A recursive PRB allocation algorithm using AMC for MIMO-OFDMA LTE systems

3GPP LTE is a suitable candidate for high quality wireless communication insurance according to the mobile users' requirements thanks to its radio link flexibility using Adaptive Modulation and Coding (AMC), Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) technologies. This paper addresses the resource allocation optimisation problem aiming to guarantee a high spectral efficiency promised over the LTE-downlink network. Therefore, we propose here a recursive Physical Resource Bloc (PRB) allocation algorithm is developed in this paper. In this context, we use the Effective Signal-to-Interference-plus-Noise Ratio (ESINR) metric to properly characterize multi-state channels conditions. Then, the basic idea of the proposed algorithm is to allocate to each mobile user its best PRB according to the highest measured ESINR in order to ensure the maximum system capacity. Simulations results show that the proposed algorithm provides better performance in terms of system capacity than other recent works thanks to its recursion procedure.
The use of intravenous hyaluronidase following narrowing of the left circumflex coronary artery in dogs

Abstract Partial occlusion of the origin of the left circumflex coronary artery has been performed in 12 dogs. Intravenous injections of hyaluronidase have been given to 18 dogs in which partial occlusion of the left circumflex coronary artery was performed. A comparison of the results in the two groups is made. No evidence was obtained which indicates that hyaluronidase influences the production of infarcts or the survival rate in dogs under the conditions of these experiments.
Causal Reasoning in Medicine: Analysis of a Protocol

The ability to identify and represent the knowledge that a human expert has about a particular domain is a key method in the creation of an expert computer system. The first part of this paper demonstrates a methodology for collecting and analyzing observations of experts at work, in order to find the conceptual framework used for the particular domain. The second part develops a representation for qualitative knowledge of the structure and behavior of a mechanism. The qualitative simulation, or envisionment, process is given a qualitative structural description of a mechanism and some initialization information, and produces a detailed description of the mechanism's behavior. The simulation process has been fully implemented, and its results are shown for a particular disease mechanisms in nephrology. This vertical slice of the construction of a cognitive model demonstrates an effective knowledge acquisition method for the purpose of determining the structure of the representation itself, not simply the content of the knowledge to be encoded in that representation. Most importantly, it demonstrates the interaction among constraints derived from the textbook knowledge of the domain, from observations of the human expert, and from the computational requirements of successful performance.
A fluid structure interaction study of a viscous mechanism for energy absorption in protective structural panels

Sandwich panels designed to resist blasts and high-velocity impacts usually dissipate most of the delivered energy through inelastic deformation of solids. A concept is explored in this study to improve the energy absorption of such structures by the addition of a viscous mechanism. The mechanism relies on the fact that when a viscous liquid is forced through narrow passages at high speeds, it undergoes high shear rates that cause viscous energy dissipation. A simple test specimen in the form of a steel tube with capillaries attached at both ends was chosen for study. Both empty and liquid-filled test specimens were subjected to experimental and simulated drop-weight impact tests and simulated blast load tests. Fluid structure interaction analyses in the form of Coupled-Eulerian-Lagrangian simulations were performed to assess the energy dissipated both by solid plastic deformation and liquid viscous dissipation in the drop-weight and blast simulations. The liquid flow speeds generated by the applied loads were found to be a critical factor in determining the contribution of the viscous mechanism. The moderate liquid flow speeds generated by the drop-weight impacts resulted in negligible viscous energy dissipation. The simulated blast loads generated much higher liquid flow speeds and as a result the viscous energy contribution to the total absorbed energy in the test specimens approached 30%. The viscosity of the liquid has a major effect on the fraction of energy absorbed in the form of viscous dissipation. Results of this study support the viability of the concept of viscous-assist for improving the ability of protective panels and structures to withstand high-speed impact and blast loads.
Compatibility test using 51chromium-labeled red blood cells in crossmatch positive patients

For the past three years, we have routinely used the one-hour in vivo survival of 51Cr-labeled donor red blood cells to select units for transfusion to patients for whom crossmatch compatible blood was unavailable. This technique successfully evaluated in vivo compatibility, thus avoiding acute hemolytic transfusion reactions in 38 problem patients. New or confirmatory data regarding the hemolytic potential of several well defined antibodies was also obtained. Antibodies which proved to be clinically insignificant included: anti-IT (all IgG), anti-Sda, anti-Kir, Mil, Oca, anti-Chido, anti-Bg, 14 of 15 “nonspecific warm autoantibodies” (three of which were associated with the ingestion of alphamethyldopa), and four of five antibodies to high-incidence antigens. Clinically significant antibodies included: anti-Yta, anti-Jkb, the antibody in PCH (with “P” specificity), one intensely hemolytic “nonspecific warm autoagglutinin,” and one of five incompletely characterized antibodies to high-incidence antigens. An acceptable in vivo compatibility test in every instance was associated with an appropriate rise in hematocrit and no clinical symptoms of hemolytic transfusion reaction.
Unequal error protection of embedded multimedia objects for packet-erasure channels

The application of forward-error-correcting codes to data organized as multiple, independent multimedia objects and encoded with modern embedded coders is investigated. Capitalizing on the strict importance-ordering characteristics of embedded encodings, the strength of the error protection is optimized such that is more important to the reconstructed quality of the dataset is assigned stronger protection. The focus of the investigation is on providing this optimization while maintaining the ability ton independently access the individual multimedia objects. Experimental results are presented for still-image objects that illustrate that the desired independent-access ability comes at a cost in reconstruction quality, and that this cost increases as the channel-loss conditions actually experienced degrade from those for which the optimal protection arrangement was designed.
Communicating uncertain experimental evidence.

Four experiments examined when laypeople attribute unexpected experimental outcomes to error, in foresight and in hindsight, along with their judgments of whether the data should be published. Participants read vignettes describing hypothetical experiments, along with the result of the initial observation, considered as either a possibility (foresight) or a reality (hindsight). Experiment 1 found that the initial observation seemed more likely to be replicated when viewed in hindsight than in foresight. The remaining experiments contrasted responses to an initial observation from 1 of the 4 studies that was either expected or unexpected (based on the predictions of participants in Experiment 1). Experiments 2A–C and Experiment 3 found that unexpected results were more likely to be attributed to methodological problems than were expected ones—but to the same degree in foresight and in hindsight. Participants in Experiment 4 had more confidence in an explanation for an unexpected outcome when it was mentioned before that outcome was revealed than when it was suggested only after the surprise was known. In all the experiments, most participants recommended collecting more data before publishing the results, especially when they attributed the results to multiple causes. The results suggest that considering the causes of unexpected experimental results in foresight may improve the evaluation and communication of those results in hindsight.
The creation and matintenance of national boundaries in Africa

A paradox is central to the nature of political boundaries in Africa: there is widespread agreement that the boundaries are arbitrary, yet the vast majority of them have remained virtually untouched since the late 1800s, when they were first demarcated. This article argues that, contrary to current theories, the present boundary system represents a rational response by both the colonialists and the present-day African leaders to the constraints imposed by the demographic and ethnographic structure of the continent. Using this framework of analysis, the article examines the institutions that formulated the decision-making rules for the creation and maintenance of boundaries in Africa, discusses the conditions under which cooperation among states has occurred, and explores the prospects for future changes in the borders of African states.
A High-Throughput, Homogeneous, Fluorescence Polarization Assay for Inhibitors of Hedgehog Protein Autoprocessing

Hedgehog (Hh) signaling plays an important role in embryonic patterning and adult stem cell renewal but has recently been found also to be involved in certain stem cell cancers. One of the first steps in Hh signaling is the autoprocessing of Hh protein, in which the C-terminal domain (Hh-C) catalyzes a cholesterol-dependent autocleavage reaction that leads to the production of the cholesterol ester of the N-terminal Hh domain (Hh-N), thereby yielding a signaling molecule that activates the Hh pathway by binding to the Patched receptor. This article describes an in vitro, homogeneous assay system that measures changes in fluorescence polarization that accompany the cholesterol-dependent autocleavage of Hh protein. The assay system makes use of a modified Hh protein in which Hh-N, which is not essential for autocleavage, is replaced by a 25-residue peptide containing a tetracysteine motif, complexed with a bisarsenical fluorophore. The assay is quite robust and easily adapted to high-throughput screening in 384-well plates with Z' factors above 0.8. It has been used to screen the National Institutes of Health Clinical Collection, which has led to the identification of 2 compounds that inhibit the cholesterol-dependent autocleavage of Hh protein at micromolar concentrations.
Small signal phasor modeling of dual active bridge series resonant DC/DC converters with multi-angle phase shift modulation

This paper presents an approach for generating small signal models of resonant converters focusing on the transformer-isolated dual active bridge series resonant converter (DABSRC) topology. The presented approach can be generalized to other active bridge resonant converters with one or more phase shift control inputs. Both steady state analysis and small signal modeling of the DABSRC are shown, and the resulting models are experimentally verified using a 1 kW prototype converter.
Analysis of the Major Metabolite of Δ9-Tetrahydrocannabinol in Urine. IV. A Comparison of Five Methods

Urine samples from 29 subjects were simultaneously analyzed for 11-noroAD-tetrahydrocannabinol-9-carboxylic acid by five previously published methods. The procedures employed were radloimmunoassay (RIA), enzyme immunoassay (EIA), high performance liquid chromatography (HPLC), gas chromatography with electron capture detector (GClECD), and gas chromatography/mass spectrometry (GC/MS). A comparison of the results showed significant correlations between the results obtained by HPLC, GC/ECD, and GC/MS procedures. As anticipated, quantitation by any of these procedures resulted in lower values than those obtained by either of the immunoassays.
Statistical analysis of generalized processor sharing scheduling discipline

In this paper, we consider the problem of providing statistical guarantees (for example, on the tail distribution of delay) under the Generalized Processor Sharing (GPS) scheduling discipline. This work is motivated by, and is an extension of, Parekh and Gallager's deterministic study of GPS scheduling discipline with leaky-bucket token controlled sessions [PG93a,b, Parekh92]. Using the exponentially bounded burstiness (E.B.B.) process model introduced in [YaSi93a] as a source traffic characterization, we establish results that extend the deterministic study of GPS: for a single GPS server in isolation, we present statistical bounds on the tail distributions of backlog and delay for each session. In the network setting, we show that networks belonging to a broad class of GPS assignments, the so-called Consistent Relative Session Treatment (CRST) GPS assignments, are stable in a stochastic sense. In particular, we establish simple bounds on the tail distribution of backlog and delay for each session in a Rate Proportional Processor Sharing (RPPS) GPS network with arbitrary topology.
Systems engineering metrics and applications in product development: A critical literature review and agenda for further research

The military-aerospace industries have several decades of experience in the application of systems engineering. In the world of complex systems developed under contract, systems engineering has a well-articulated, generally accepted, client-mandated methodology. This is not the case currently in most commercially oriented research and development organizations. Unlike the military-aerospace environment, it is not widely accepted that systems engineering can or will deliver value within commercial enterprises. This said, it is possible that a systems engineering-like methodology may be routinely employed but not so stated, or is recognized under a different label. This seems likely since complex products continue to be successfully developed and commercialized via the use of methods that are closely related to systems engineering. The purpose of this paper is to establish the groundwork for measuring the effectiveness of the systems engineering methodology, and closely associated analogs, as part of the product development process in a commercial research and development organization. In this paper, we review the literature in systems engineering and related fields to identify measurement issues and methodologies, specific metrics proposed and in use, and case studies and best practices. We also identify gaps in the literature and propose the next steps in a research agenda. © 2008 Wiley Periodicals, Inc. Syst Eng
Metabolism of the pancreatic carcinogen n-nitroso-2,6-dimethylmorpholine by hamster liver and component cells of pancreas

Abstract N-Nitroso-2,6-dimethylmorpholine (NNDM) is an indirect nitrosamine carcinogen which induces ductal adenocarcinoma of the pancreas in the Syrian golden hamster. NNDM is oxidized by normal male hamster pancreas postmitochondrial supernatants (S-9) in the presence of reduced nicotinamide adenine dinucleotide phosphate and oxygen to give three major identifiable metabolites as measured by high-pressure liquid chromatography. The major products are N-nitrosobis(2-hydroxypropyl)amine, N-nitroso(2-hydroxypropyl) (2-oxopropyl)amine, and N-nitrosobis(2-oxopropyl)amine. Two other major metabolites have been detected, one which elutes near the solvent front and is referred to as X1, and one which is more hydrophobic than N-nitrosobis(2-oxopropyl)amine and is called X2. The rates of formation of N-nitrosobis(2-hydroxypropyl)amine, N-nitroso(2-hydroxypropyl) (2-oxopropyl)amine, N-nitrosobis-(2-oxopropyl)amine, X1, and X2 were linear with protein up to a final concentration of 15 mg of pancreatic S-9 per ml. The in vitro metabolism of NNDM by liver and pancreas S-9 and microsomes was compared. Although the liver subcellular fractions only produced two major metabolites, N-nitroso(2-hydroxypropyl)(2-oxopropyl)amine and X1, under initial rate conditions the liver enzymes were greater than 40 times more active than the pancreatic enzymes with respect to the overall metabolism of NNDM. The enzyme(s) for the initial oxidative metabolism of NNDM are associated with the microsomes in the liver and the pancreas. However, the metabolite profiles obtained with pancreatic S-9 preparations are different from those observed with pancreatic microsomes, suggesting the involvement of cytosolic proteins in modulating the pancreatic metabolism of NNDM. Acinar and islet cell S-9 fractions metabolize NNDM at similar rates and exhibit a 2-fold increase in NNDM metabolism over whole pancreas S-9. However, the metabolite profiles for the two cell types are very different. Pretreatment of hamsters with 2,3,7,8-tetrachlorodibenzo-p-dioxin results in a marked increase in the rate of NNDM metabolism by both acinar and islet cells. However, the two cell types exhibit different patterns of induction as measured by changes in the metabolite profiles. Pretreatment of hamsters with 2,3,7,8-tetrachlorodibenzo-p-dioxin results in a greater than 20-fold induction of aryl hydrocarbon hydroxylase activity in acinar cell S-9, whereas there is no induction of aryl hydrocarbon hydroxylase activity in the islet cell S-9. These results suggest the presence of different forms of the microsomal mixed-function oxidases in these two pancreatic cell types. Duct cells can also metabolize NNDM to an active form as demonstrated by unscheduled DNA synthesis in the nuclei of pancreatic duct epithelial cells after exposure to NNDM. These results provide additional evidence that pancreatic carcinogens are activated within the target cell(s) of the pancreas.
Short communication: Effect of active food packaging materials on fluid milk quality and shelf life

Active packaging, in which active agents are embedded into or on the surface of food packaging materials, can enhance the nutritive value, economics, and stability of food, as well as enable in-package processing. In one embodiment of active food packaging, lactase was covalently immobilized onto packaging films for in-package lactose hydrolysis. In prior work, lactase was covalently bound to low-density polyethylene using polyethyleneimine and glutaraldehyde cross-linkers to form the packaging film. Because of the potential contaminants of proteases, lipases, and spoilage organisms in typical enzyme preparations, the goal of the current work was to determine the effect of immobilized-lactase active packaging technology on unanticipated side effects, such as shortened shelf-life and reduced product quality. Results suggested no evidence of lipase or protease activity on the active packaging films, indicating that such active packaging films could enable in-package lactose hydrolysis without adversely affecting product quality in terms of dairy protein or lipid stability. Storage stability studies indicated that lactase did not migrate from the film over a 49-d period, and that dry storage resulted in 13.41% retained activity, whereas wet storage conditions enabled retention of 62.52% activity. Results of a standard plate count indicated that the film modification reagents introduced minor microbial contamination; however, the microbial population remained under the 20,000 cfu/mL limit through the manufacturer’s suggested 14-d storage period for all film samples. This suggests that commercially produced immobilized lactase active packaging should use purified cross-linkers and enzymes. Characterization of unanticipated effects of active packaging on food quality reported here is important in demonstrating the commercial potential of such technologies.
An N-state driven policy-based network management to control end-end network behaviors

A large scale network simultaneously experiences multiple and varied events that degrade its ability to serve its customers. Network management of large networks that span multiple networks, network technologies, network events (faults, performance, security, other disruptions) is a multidimensional problem. While, policy based network management frameworks have been proposed to help manage the complexity, additional frameworks are needed to help manage network of networks. In this paper, a finite state machine based aggregation of network, events, N-State, is proposed, as a framework to manage complex networks and as a PBNM framework extension to manage network of networks. N-state, targeted network behavior for each state, and collaboratively developed PBNM policies mapped to state and targeted behavior, provide a means for network operators to comprehend overall network situation, assess overall network degradation, collaborate in restoration of network services and intervene when necessary.
Empirical Entropy Manipulation for Real-World Problems

No finite sample is sufficient to determine the density, and therefore the entropy, of a signal directly. Some assumption about either the functional form of the density or about its smoothness is necessary. Both amount to a prior over the space of possible density functions. By far the most common approach is to assume that the density has a parametric form. By contrast we derive a differential learning rule called EMMA that optimizes entropy by way of kernel density estimation. Entropy and its derivative can then be calculated by sampling from this density estimate. The resulting parameter update rule is surprisingly simple and efficient. We will show how EMMA can be used to detect and correct corruption in magnetic resonance images (MRI). This application is beyond the scope of existing parametric entropy models.
Vertebrate spinal commissural neurons: a model system for studying axon guidance beyond the midline

For bilaterally symmetric organisms, the transfer of information between the left and right side of the nervous system is mediated by commissures formed by neurons that project their axons across the body midline to the contralateral side of the central nervous system (CNS). After crossing the midline, many of these axons must travel long distances to reach their targets, including those that extend from spinal commissural neurons. Owing to the highly stereotyped trajectories of spinal commissural neurons that can be divided into several segments as these axons project to their targets, it is an ideal system for investigators to ask fundamental questions related to mechanisms of short- and long-range axon guidance, fasciculation, and choice point decisions at the midline intermediate target. In addition, studies of patterning genes of the nervous system have revealed complex transcription factor codes that function in a combinatorial fashion to specify individual classes of spinal neurons including commissural neurons. Despite these advances and the functional importance of spinal commissural neurons in mediating the transfer of external sensory information from the peripheral nervous system (PNS) to the CNS, only a handful of studies have begun to elucidate the mechanistic logic underlying their long-range pathfinding and the characterization of their synaptic targets. Using in vitro assays, in vivo labeling methodologies, in combination with both loss- and gain-of-function experiments, several studies have revealed that the molecular mechanisms of long-range spinal commissural axon pathfinding involve an interplay between classical axon guidance cues, morphogens and cell adhesion molecules. For further resources related to this article, please visit the WIREs website.
A Note on the Validity of Self-Reports of Absenteeism

The general unavailability of and difficulty associated with obtaining records-based data on absenteeism suggests the potential value of self-report data for those conducting research on absenteeism. This should not be recommended, however, until the validity of these self-report measures is assessed. In this paper, we compare records-based and self-report measures of absenteeism for the same employees for the same period of time. We find that although the univariate descriptive data for the two measures are similar, the correlation between the two is .299. Although this is in the expected direction, its magnitude is small enough for us to question the validity of self- report measures of absenteeism. Several suggestions are offered for additional study of this.
Politics and privatization decisions in four American cities

Public choice theory has emphasized economic explanations of privatization decisions, while often neglecting the politics associated with the decision-making process. This research finds that the political context is important in understanding why American municipal governments decide whether or not to privatize a service. Four case studies reveal that the degree to which the decision-making process is politicized is a factor warranting our attention.
Association of diacylglycerol kinase ζ with protein kinase C α: spatial regulation of diacylglycerol signaling

Activation of PKC depends on the availability of DAG, a signaling lipid that is tightly and dynamically regulated. DAG kinase (DGK) terminates DAG signaling by converting it to phosphatidic acid. Here, we demonstrate that DGKzeta inhibits PKCalpha activity and that DGK activity is required for this inhibition. We also show that DGKzeta directly interacts with PKCalpha in a signaling complex and that the binding site in DGKzeta is located within the catalytic domain. Because PKCalpha can phosphorylate the myristoylated alanine-rich C-kinase substrate (MARCKS) motif of DGKzeta, we tested whether this modification could affect their interaction. Phosphorylation of this motif significantly attenuated coimmunoprecipitation of DGKzeta and PKCalpha and abolished their colocalization in cells, indicating that it negatively regulates binding. Expression of a phosphorylation-mimicking DGKzeta mutant that was unable to bind PKCalpha did not inhibit PKCalpha activity. Together, our results suggest that DGKzeta spatially regulates PKCalpha activity by attenuating local accumulation of signaling DAG. This regulation is impaired by PKCalpha-mediated DGKzeta phosphorylation.