cssi/SciSciGPT-SciSciNet huggingface dataset:
K ir 5.1-dependent CO 2 /H + -sensitive currents contribute to astrocyte heterogeneity across brain regions

Astrocyte heterogeneity is an emerging concept in which astrocytes within or between brain regions show variable morphological and/or gene expression profiles that presumably reflect different functional roles. Recent evidence indicates that retrotrapezoid nucleus (RTN) astrocytes sense changes in tissue CO2/ H+ to regulate respiratory activity; however, mechanism(s) by which they do so remain unclear. Alterations in inward K+ currents represent a potential mechanism by which CO2 /H+ signals may be conveyed to neurons. Here, we use slice electrophysiology in rats of either sex to show that RTN astrocytes intrinsically respond to CO2 /H+ by inhibition of an inward rectifying potassium (Kir ) conductance and depolarization of the membrane, while cortical astrocytes do not exhibit such CO2 /H+ -sensitive properties. Application of Ba2+ mimics the effect of CO2 /H+ on RTN astrocytes as measured by reductions in astrocyte Kir -like currents and increased RTN neuronal firing. These CO2 /H+ -sensitive currents increase developmentally, in parallel to an increased expression in Kir 4.1 and Kir 5.1 in the brainstem. Finally, the involvement of Kir 5.1 in the CO2 /H+ -sensitive current was verified using a Kir5.1 KO rat. These data suggest that Kir inhibition by CO2 /H+ may govern the degree to which astrocytes mediate downstream chemoreceptive signaling events through cell-autonomous mechanisms. These results identify Kir channels as potentially important regional CO2 /H+ sensors early in development, thus expanding our understanding of how astrocyte heterogeneity may uniquely support specific neural circuits and behaviors.
The Hardness of Sampling Connected Subgraphs

We consider the problem of sampling connected induced subgraphs of a given input graph G. Our first result is that an efficient algorithm to approximately sample connected induced subgraphs of a given size (the size is specified in the input) does not exist unless RP = NP. We then focus on the problem of approximately sampling connected induced subgraphs with a bias, more precisely we consider a distribution where the probability of a connected subgraph induced by \(S\subseteq V(G)\) is proportional to \(\lambda ^{|S|}\). When the input graph G has maximum degree d we identify a threshold \(\lambda _d=\frac{(d-1)^{(d-1)}}{d^d}\). For \(0< \lambda < \lambda _d\) there exists a trivial efficient sampler for the problem, and for \(\lambda _d<\lambda <1\) an efficient approximate sampler does not exist unless RP = NP. Finally, we show local Markov chains are unlikely to be effective at approximately sampling connected subgraphs.
Effects of Spanish vocabulary knowledge on the English word knowledge and listening comprehension of bilingual students

The purpose of the current study was to examine the influence of L1 (i.e. Spanish) receptive vocabulary on both expressive and receptive knowledge of target vocabulary words taught through L2 (i.e....
Exposure to particulate matter, prenatal depressive symptoms and HPA axis dysregulation.

Abstract Background The prevalence of depression during pregnancy is on the rise, affecting women's well-being and their children's health outcomes. Preliminary studies suggest that exposure to air pollution during pregnancy may play a role in development of depressive symptoms. In addition, pollution has been linked to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, our brain's primary stress response system. The purpose of this study was to examine the association of air pollution exposure during pregnancy to prenatal depressive symptoms. We also evaluated whether cortisol, the hormonal endpoint of HPA activation, mediated the relationship between exposure to pollution and prenatal depression. Methods Women were recruited in obstetric clinics during their third trimester of pregnancy. They completed the Patient Health Questionnaire-9 to assess depression and provided salivary samples at 4 times during the day for 2 days. Four measures of cortisol were calculated from salivary assays: average cortisol level, cortisol awakening response (CAR), diurnal cortisol slope (DCS), and area under the curve (AUCG). We acquired data on particulate matter with a diameter of 2.5 μm (PM2.5) or less within each woman's residential area from public records of the air quality control district. Structural equation modeling was used to analyze the aims. Results Increased prenatal exposure to PM2.5 across pregnancy was associated with more severe depressive symptoms during the 3rd trimester (β = 0.14, p = 0.02). Greater PM2.5 exposure also had significant relationships with both higher cortisol AUCG (β = 15.933, p = 0.005) and average cortisol levels (β = 0.018, p = 0.023) among women. However, no cortisol parameter appeared to mediate the relationship between PM2.5 exposure and depressive symptoms. Conclusions Findings suggest pregnancy may be a critical window of sensitivity to PM2.5 exposure that escalates depression risk and induces activation of the HPA axis, evidenced in greater overall cortisol concentration. Further research is needed to identify mechanisms underlying the effects of particulate matter, especially potential methylation of glucocorticoid or serotonin transporter genes that may elicit changes in both depression and the stress response system. In addition, assessment of depression appears warranted for pregnant women in regions known for high pollution.
A 250-600 MHz Ring Oscillator-Based Phase-Locked Loop for Implantable Wireline Applications, Using 1.0 V Supply in 180 nm CMOS

This article introduces a low power frequency synthesizer designed for high-speed implantable wireline applications, based on the integer-N phase-locked loop (PLL) architecture. The PLL is designed in a standard 180 nm CMOS process and post-layout simulation results are presented. It provides 8 outputs from 4 delay cells, precisely at 45° apart to facilitate the required parallelism in the transmitter’s datapath. The ring oscillator is based on interpolating inverter delay cells to create the precise phase difference. The design works between 250 MHz to 600 MHz, provides tuning options for robust operation over process variations, draws 2.0-2.6 mW across corners from ±500 mV split supplies, and exhibits a typical phase noise of -83 dBc/Hz at 1 MHz of frequency offset. The typical RMS jitter over 10,000 cycles is 28 ps for a 600 MHz clock. The featured clock synthesizer provides a broader range of operational frequency compared to previous works on multi-phase ring oscillator-based clock synthesizers by utilizing a combination of programmable charge pump current, capacitive load, and tunable biasing. This frequency synthesizer is suitable for power-constrained system-on-chip applications that benefit from strong analog capabilities, such as implantable devices that need transceivers operating in the ISM band.
Property Prices and Speculative Bubbles : Evidence From Hong Kong SAR

This paper examines the determinants of residential property prices in Hong Kong SAR during 1980–98. It uses time-series analysis techniques to characterize price developments, establish empirical regularities, and provide measures of the deviations of actual price changes from “trend.” The analysis suggests that at the peak of the boom, in mid-1997, the level of property prices may have been 40–45 percent above levels suggested by developments in “fundamentals.” The analysis highlights the role of demand-side factors, and the data are not inconsistent with the notion that the property market may be subject to speculative bubbles.
Choice and change of measures in performance measurement models

Abstract This paper uses management control, resource-based, systems-based and contingency-based strategy theories to describe a large U.S. manufacturing company's efforts to improve profitability by designing and using a performance measurement model (PMM). This PMM includes multiple performance measures relevant to its distribution channel for products, repair parts and maintenance services. The PMM is intended to reflect the company's understanding of performance relations among strategic resources, operational capabilities, and desired financial outcomes. The PMM also reflects its intended distribution strategy, the types of performance necessary to achieve that strategy by its distributors, and its desired financial outcomes. Furthermore, the company uses the model to evaluate its North American distributors and intends to use these evaluations as a partial basis for annual and long-term rewards. Thus, the PMM embodies the measurable portion of the firm's management control system of its distribution channel. The study addresses four research questions: (1) Are measure attributes important considerations for performance measure choice? (2) Does the importance of attributes differ according to firm strategy? (3) Does the importance of attributes for design and use differ according to firm strategy? (4) Does a company trade-off some individual attributes for others? The questions are investigated using qualitative and quantitative analyses of archival documents and interviews with top managers and distributors. Principal findings are that measure attributes are important considerations for choice and change of performance measures, design attributes are more important than use attributes, the importance of attributes does not appear to differ according to strategy, and some individual attributes are traded-off for other attributes.
Disease-discordant twin studies of epigenetics and cancer

Abstract Epigenetic mechanisms that can influence gene expression include histone acetylation and DNA methylation. This chapter reviews epigenetic studies of MZ twin pairs discordant for a history of cancer. Each of the eight published papers identified by systematic search compared levels of methylation in DNA from blood, saliva and/or skin fibroblasts between affected and cancer-free members of each twin pair. The number of twin pairs examined ranged from 1 to 41. These studies had two general objectives: investigating the hypothesis that differential DNA methylation could be responsible for discordant phenotypes of genetically identical twin pairs, and discovery of biomarkers for early detection of disease. Limitations that will need to be addressed in future studies of this type include small sample size, relevance of tissue tested to target tissue, artifact that could arise from differential mixtures of cell types, and timing of the sample collection with respect to diagnosis and treatment. The studies reviewed here illustrate the rationale whereby observational studies of epigenetic state in phenotype-discordant MZ twin pairs may contribute uniquely to both etiologic and clinical-translational research.
Mimic: An adaptive algorithm for multivariate time series classification.

Time series data are valuable but are often inscrutable. Gaining trust in time series classifiers for finance, healthcare, and other critical applications may rely on creating interpretable models. Researchers have previously been forced to decide between interpretable methods that lack predictive power and deep learning methods that lack transparency. In this paper, we propose a novel Mimic algorithm that retains the predictive accuracy of the strongest classifiers while introducing interpretability. Mimic mirrors the learning method of an existing multivariate time series classifier while simultaneously producing a visual representation that enhances user understanding of the learned model. Experiments on 26 time series datasets support Mimic's ability to imitate a variety of time series classifiers visually and accurately.
Identification of large space structures - Overview

The system identification process presently discussed for the case of large space structures uses the observed input to a system and its observed response, or output, to derive an analytical model of the system which can then be used to predict its response to future inputs. Due to their size and complexity, as well as the intrinsic difficulty of identifying the environment in which they function, large space structures will require vast amounts of information, encompassing both experimental and analytical data for identification. A status evaluation is made of the structural system identification literature to date.
In vivo incorporation of [2-3H]-myo-inositol into frog opsin

The in vivo incorporation of [2-3H]-myo-inositol into frog retinal rod outer segment membranes was examined. About 25% of the recovered radioactivity was found to be protein-associated. Following acid hydrolysis of this material and extraction with hexane, all the radioactivity remained in the aqueous phase, indicating that the label was not in fatty acids. Following ion exchange column chromatography of the hydrolysate, the major radioactive compound comigrated on TLC with an internal standard of [U-14C]-myo-inositol. SDS polyacrylamide gel electrophoresis of unextracted membranes indicated that the majority of the label was associated with opsin. These results indicate that [2-3H]-myo-inositol was incorporated in vivo into opsin, presumably with retention of its chemical identity.
C4 Deficiency Is a Predisposing Factor for Streptococcus pneumoniae–Induced Autoantibody Production

Reductions in C4 levels may predispose individuals to infection with encapsulated bacteria as well as autoimmunity. In this study, we examined the role C4 has in protection against Streptococcus pneumoniae –induced autoimmunity. Mild respiratory infection with serotype 19F pneumococci selectively induced systemic anti-dsDNA IgA production in naive C4 −/− mice, but not in C3 −/− or wild-type mice. Systemic challenge with virulent serotype 3 pneumococci also induced anti-dsDNA IgA production in immune C4 −/− mice. Remarkably, pneumococcal polysaccharide (PPS) vaccination alone induced C4 −/− mice to produce increased anti-dsDNA IgA levels that were maintained in some mice for months. These effects were most pronounced in female C4 −/− mice. Importantly, immunization-induced increases in anti-dsDNA IgA levels were strongly associated with increased IgA deposition in kidneys. Cross-reactivity between pneumococcal Ags and dsDNA played a partial role in the induction of anti-dsDNA IgA, but a major role for PPS-associated TLR2 agonists was also revealed. Administration of the TLR2/4 antagonist, OxPAPC, at the time of PPS immunization completely blocked the production of anti-dsDNA IgA in C4 −/− mice without suppressing PPS-specific Ab production. The TLR2 agonist, Pam3CSK4, similarly induced anti-dsDNA IgA production in C4 −/− mice, which OxPAPC also prevented. LPS, a TLR4 agonist, had no effect. Pam3CSK4, but not LPS, also induced dsDNA-specific IgA production by C4 −/− splenic IgA + B cells in vitro, indicating that TLR2 agonists can stimulate autoantibody production via B cell–intrinsic mechanisms. Collectively, our results show an important role for C4 in suppressing autoantibody production elicited by cross-reactive Ags and TLR2 agonists associated with S. pneumoniae .
Learning to find a shape

We studied the transition of stimuli from novel to familiar in visual search and in the guidance of attention to a particular object. Ability to identify an object improved dramatically over several days of training. The learning was specific for the object's position in the visual field, orientation and configuration. Improvement was initially localized to one or two positions near the fixation spot and then expanded radially to include the full area of the stimulus array. Characteristics of this learning process may reflect a shift in the cortical representation of complex features toward earlier stages in the visual pathway.
Optimal Design of Urban Wastewater Collection Networks

This paper addresses itself to the question of obtaining the minimum cost design for a wastewater collection network. The concept of optimization is explored with respect to overall collection networks. Present design methodologies and recent developments in both network layout and design are explored. The design problems of selecting an optimal mix of pipe diameters and slopes, given a set of economic and technological inputs as well as a network layout is then formulated as a separable convex programming problem. The formulation guarantees the generation of a global optimal solution, and a numerical solution can be obtained using existing commercially available computer software. The paper concludes with an evaluation of the developed procedure and its possible adoption in everyday sewer design.
Veterans interests and the transition to government growth: 1870–1915

Civil War veterans were the first interest group to use their political power to obtain substantial monetary transfers from the U.S. Treasury. Veterans supported the Republican party, and in exchange Republicans provided increasingly generous veterans benefits, placing a strain on the Treasury that led toward a demand for increased taxes. Veterans also established a precedent that other groups could follow to petition the goverment for economic benefits, shaping the transformation of American government in the Progressive era which led to the substantial growth of the federal government in the 20th century.
A discrete entropy power inequality for uniform distributions

We explore various tempting conjectures for discrete entropy power inequalities on the integers, proving both positive results for interesting subclasses of distributions and negative results that falsify some of the conjectures in general. In particular, we show that an inequality very similar to the usual entropy power inequality holds for uniform distributions over finite subsets of the integers.
Pressure Stabilization of Proteins from Extreme Thermophiles

We describe the stabilization by pressure of enzymes, including a hydrogenase from Methanococcus jannaschii, an extremely thermophilic deep-sea methanogen. This is the first published report of proteins from thermophiles being stabilized by pressure. Inactivation studies of partially purified hydrogenases from an extreme thermophile (Methanococcus igneus), a moderate thermophile (Methanococcus thermolithotrophicus), and a mesophile (Methanococcus maripaludis), all from shallow marine sites, show that pressure stabilization is not unique to enzymes isolated from high-pressure environments. These studies suggest that pressure stabilization of an enzyme may be related to its thermophilicity. Further experiments comparing the effects of increased pressure on the stability of α-glucosidases from the hyperthermophile Pyrococcus furiosus and Saccharomyces cerevisiae support this possibility. We have also examined pressure effects on several highly homologous glyceraldehyde-3-phosphate dehydrogenases from mesophilic and thermophilic sources and a rubredoxin from P. furiosus. The results suggest that hydrophobic interactions, which have been implicated in the stabilization of many thermophilic proteins, contribute to the pressure stabilization of enzymes from thermophiles.
COHORT DIFFERENCES IN THE TRANSITION TO MOTHERHOOD: The Variable Effects of Education and Employment Before Marriage

Although research has found that educational attainment is a major predictor of age at first childbirth, this association may not be consistent across cohorts. In this article, we examine the adult...
SOCIAL CONCERN AND CRIME: MOVING BEYOND THE ASSUMPTION OF SIMPLE SELF-INTEREST

Most leading crime theories and crime-control policies are based on the assumption that people are self-interested. But recent work in a variety of fields has challenged this assumption, suggesting that people are both self-interested and socially concerned. Social concern involves biologically based inclinations that sometimes lead people to give more consideration to others than to their own interests. These inclinations include caring about others, forming close ties to and cooperating with others, following certain moral intuitions, and conforming. This article describes the nature of and evidence for social concern, as well as the ways in which social factors shape social concern. The article then presents a theory of social concern and crime. Social concern has direct, indirect, mediating, and conditioning effects on crime. Although social concern generally reduces the likelihood of crime, it has little effect on or increases crime under certain conditions.
Role of various DNA repair pathways in chromosomal inversion formation in CHO mutants

AbstractPurpose: In an effort to better understand the formation of chromosomal inversions, we investigated the role of various DNA repair pathways, including the non-homologous end joining (NHEJ), homologous recombination (HR), and Fanconi Anemia (FA) repair pathways for the formation of radiation induced chromosomal inversions.Materials and methods: CHO10B2 wild type, CHO DNA repair-deficient, and CHO DNA repair-deficient corrected mutant cells were synchronized into G1 phase and exposed to gamma-rays. First post-irradiation metaphase cells were analyzed for chromosomal inversions by a differential chromatid staining technique involving a single cycle pre-irradiation ethynyl-uridine treatment and statistic calculations.Results: It was observed that inhibition of the NHEJ pathway resulted in an overall decrease in the number of radiation-induced inversions, roughly a 50% decrease when compared to the CHO wild type. Interestingly, inhibition of the FA pathway resulted in an increase in both the number of ...
Retained wound vacuum foam in non-healing wounds: a real possibility

Negative pressure wound therpay (NPWT) has revolutionised the management of chronic wounds, particularly pressure ulcers (PU). Frequently, PUs are too large to close primarily, so NPWT is used to assist in management on an outpatient basis. If not closely monitored, NPWT closure foam can be accidentally left in patients. Here we describe two cases where NPWT closure foam was left in patients resulting in persistent infections. Additionally, some suggestions of how to help avoid these should be 'never' events are provided.
Heritage recording applications of high resolution 3D imaging

Summary form only given. The National Research Council of Canada (NRC) has developed several high-resolution 3D imaging systems as well as data modeling and display software for heritage recording applications. Numerous pilot applications development projects have been undertaken in collaboration with several Canadian museums as well as with international partners in China, Italy, the USA, the UK, France and Israel. The systems have been used to scan archaeological site features, ethnographic collections, paintings, sculptures and architectural elements on historic buildings and the results used for a wide range of heritage recording applications including archival documentation, research, conservation, replication as well as interactive 3D VR Theatre and virtual museum Web applications. For example, in 1999 and again in 2001, in collaboration with one of NRC's industrial partners, Innovision 3D, The Canadian Foundation for the Preservation of Chinese Cultural and Historical Treasures and the State Administration of Cultural Heritage (SACH), it has been used in a pilot project to demonstrate the heritage recording applications of the 3D imaging technology in the Three Gorges area of China. The purpose of this presentation is to present an overview of the imaging systems and the heritage recording applications demonstrated to date.
From Lion to Lamb: Exemplary Deaths in Chronicles of the Middle English Period

In their depiction of death and dying medieval English chroniclers from the twelfth to the fifteenth centuries reveal certain similarities and consistencies which allow us to evaluate them as expressive of their times and their contemporaries' modes of perception. This article focuses on certain terms and modes of classification in which medieval chroniclers perceived death as a physical event with enormous moral consequences. The purpose of this article is to show with the method of literary analysis applied to historical texts—in particular one specific account of the death of King Richard the Lionheart—how certain patterns of evaluation can both conceal and reveal collective and individual assessments of death.
Performance of a general location model with an ignorable missing-data assumption in a multivariate mental health services study

In a study of the impact of case management teams in a publicly funded mental health programme, mental health patients were interviewed about a variety of outcomes suggestive of successful community adaptation, such as support from family and friends and avoidance of legal problems. Because outcome data were missing for a number of patients, a follow-up study was carried out to obtain this information form previous non-responders whenever possible. Because the data of interest were multivariate and included both continuous and categorical variables, a candidate approach for handling incomplete data in the absence of follow-up data would have been to fit a general location model, presumably with log-linear constraints on cell probabilities to avoid overfitting of the data. Here, we use available follow-up data to investigate the performance of a series of general location models with ignorable non-response. We note some problems with this approach and embed the discussion of this example in a broader consideration of the role of ignorable and non-ignorable models in applied research.
Effect of insulin on structural sugars in adipose tissue.

Hexosamine and acid mucopolysaccharide concentrations were measured in the fat-free, dry residue (“stroma”) of epididymal adipose tissue from normal rats and from rats made obese by insulin. The hexosamine concentration was 6.81 ±0.267 (SE) jug/mg stroma over a wide range of body weights in normal rats. Adipose tissue from rats given insulin for from 7 to 28 days contained the same proportion of stroma as that from normal rats, but concentrations of hexosamine and acid mucopolysaccharides within the stroma were greatly reduced. Enzymatic digests of stroma on fractionation yielded evidence of hyaluronic acid, chondroitin sulfate and heparin. Of the 3 fractions, hyaluronic acid was reduced the most by insulin. Serum hexosamine and protein-bound hexose levels were lower, and seromucoid levels were higher, in rats given insulin. It appears, from these and other data cited, that insulin impairs the synthesis of certain structural sugars found in adipose tissue and serum. An increase in the rate of breakdown of...
Intermittent Reversal of Flow in a Case of Patent Ductus Arteriosus A Physiologic Study with Autopsy Findings

The direction of blood shunts between abnormally communicating ventricles or large vessels is dependent upon blood pressure differences in the adjacent structures, and upon the respective vascular resistance in both circulating systems distal to the communication. In a case of patent ductus arteriosus, physiologic measurements suggested that the direction of blood flow through the ductus was reversed intermittently during the systolic phase of the cardiac cycle. Pathologic studies confirmed the hypothesis by demonstrating the presence of "impingement" plaques on the aortic as well as on the pulmonary artery walls opposite the lumen of the ductus. They also gave information concerning the lesions in the pulmonary vascular bed which might be held responsible for the considerable increase in resistance, the pulmonary systolic hypertension and, attendant to it, the cyclic reversal of blood flow.
A rapid ATP affinity-based purification for the human non-receptor tyrosine kinase c-Src.

Abstract The non-receptor tyrosine kinase c-Src plays a central role in a variety of cell signaling pathways that regulate cell growth, differentiation, apoptosis, and other important cellular processes. An 85-amino acid N-terminal deletion construct of c-Src (ΔN85 c-Src) has been structurally characterized and used extensively in biochemical and biophysical studies. In this report, we have established a relatively rapid, simplified purification of ΔN85 c-Src from recombinant baculovirus-infected insect cells. Q-Sepharose anion-exchange and aminophenyl-ATP affinity chromatography were used to isolate 5 mg of >98% pure ΔN85 c-Src from 900 mg of total soluble protein. The specific activity of ΔN85 c-Src (20 U mg −1 ) was found to be ⩾5-fold greater than previously reported values. A lag in the autophosphorylation kinetics of ΔN85 c-Src was observed, and the reaction occurred with observed first-order rate constants k 1 = 0.20 ± 0.01 min −1 and k 2 = 0.38 ± 0.01 min −1 under the experimental conditions used. Steady-state kinetic analysis of peptide phosphorylation by ΔN85 c-Src gave K m values of 99 ± 23 μM and 190 ± 30 μM for the peptide and ATP substrates, respectively, and a value of k cat = 17 ± 2 s −1 . Overall, we present a dramatically improved purification strategy that represents a simplified, relatively rapid protocol for the isolation of milligram quantities of ΔN85 c-Src required for rigorous structure–function and inhibition studies that rely on a pre-steady-state kinetic approach.
At the Sesquicentennial of Origin

Collectively, these essays survey the current state and future prospects of the major areas within evolutionary biology.
Isotopic Biogeochemistry of Marine Organic Carbon

The ocean accounts for over 90% of the active pools of carbon on the Earth’s surface, with over 95% of marine carbon in the form of dissolved inorganic carbon (DIC) (Hedges and Keil 1995). Organic carbon dissolved in the ocean, suspended as particles or cells, and accumulating in sediments together constitute the other significant fractions of marine carbon, with organic carbon in the water column similar in quantity to the current atmospheric inventory of carbon dioxide. Isotopic partitioning among various inorganic and organic carbon phases reflects biological, physical and chemical processes, and the resulting fractionations are important tools in the study of modern and ancient carbon cycling. The focus of this review is on the isotopic geochemistry of marine organic carbon. It will begin by setting the stage with the isotopic patterns of DIC in the modern oceans. As will be discussed below, the distribution of inorganic carbon and related nutrient concentrations as well as DIC isotopic compositions are important influences on the quantity and isotopic character of organic carbon produced in marine surface waters. The remainder of the review will discuss isotope fractionation associated with the production and preservation of marine organic carbon. The combination of organic matter composition and 13C content is a potentially powerful approach for addressing the nature and pace of ecological and environmental change both in the modern and ancient ocean. This work reviews biogeochemical processes that generate, transform and ultimately preserve such signatures in marine sediments. The first truly global measurements of DIC δ13C values were produced as a result of the Geochemical Ocean Sections Study (GEOSECS). The resulting data were published in a series of articles by Kroopnick and colleagues (Kroopnick et al. 1977; Kroopnick 1980, 1985) and summarized by Takahashi et al. (1980, 1981). A striking outcome of this …
Spermiogenesis in an iceryine coccid, Steatococcus tuberculatus Morrison. An electron microscopic study.

The spermatozoon of Steatococcus is a motile filament containing a core of two chromosomes arranged in tandem and surrounded by more than 80 microtubules in 2 1/2 concentric rings. Two sperm develop from each binucleate spermatid in the form of long papillae. From the zone corresponding to the pole of the previous division microtubules appear and lengthen, assembly apparently occurring at their proximal undifferentiated ends. As they extend, they presumably push out the cytoplasmic papilla and co-extend a nuclear papilla through bridges with the nuclear envelope. Chromatin, attached to the envelope, is thus carried into the papilla, the shorter chromosome in the lead. 100 A chromatin filaments are reduced to 20 A and aligned as they enter the papilla. The filaments transform into 100 A tubular fibrils, presumably by supercoiling. These then pack hexagonally, aggregate further into packed axial filaments, and finally condense into a nearly solid core in the mature sperm. Completed papillae (sperm) detach from the spermatid leaving behind nuclei devoid of chromatin. Following cycles of spiralization and despiralization, the sperm are bundled into hexagonal packs of 32 in register by cyst wall cells. The latter form primary and secondary sheaths and lay down a matrix within the bundle. As originally reported by Hughes Schrader (1946), no evidence of centriole, acrosome, mitochondrial derivative or structure suggesting flagellar axoneme is found in either the developing papilla or the mature sperm. The microtubules determine the axis of the developing sperm; polarity is set by the direction of sperm motion and is homologous with most flagellate sperm in that the nuclear material is anterior and the microtubule initiating center is posterior. All of the functions attributed to microtubules are manifest in differentiation of this sperm: extension, support, translocation and motility.
Protein side-chain dynamics as observed by solution- and solid-state NMR spectroscopy: a similarity revealed.

In this paper, we seek to compare the internal dynamics of a small globular protein, SH3 domain from α-spectrin, in solution and in a crystalline state. The comparison involves side-chain methyl 13C R1 relaxation rates that are highly sensitive to local dynamics in the vicinity of the methyl site. To conduct the relaxation measurements, protein samples have been prepared using specially labeled α-ketoisovalerate precursors, resulting in selective incorporation of the 1H−13C spin pair in one or both methyl groups of the valine and leucine side chains. The sparse labeling pattern in an otherwise deuterated sample makes it possible to record high-resolution 13C, 1H solid-state spectra using magic angle spinning experiment with a MAS frequency of 22 kHz. Furthermore, this labeling scheme avoids proton-driven 13C−13C spin-diffusion effects, thus allowing for accurate measurements of 13C R1 relaxation in the individual methyl groups. While the relaxation response from a polycrystalline sample is generally expec...
Brightness effects on color pecking preferences in dark-hatched domestic chicks

Color pecking preferences in day-old, dark-hatched domestic chicks of 2 breeds were studied as a function of (1) target luminance (dim, medium, or bright) when testing was in darkness and in the light (Experiments I and II): (2) method of equilibrating target brightnesses (i.e., objectively or subjectively: Experiments III and IV); and (3) ambient brightness (dim, medium, or bright; Experiment IV). White Leghorns were found to peck sooner and more often than New Hampshires. Under all conditions of target and ambient brightness, results revealed the previously reported bimodal (V-shaped) color preference function with peak preferences in the blue-violet and orange regions of the spectrum and minimal at green. The only brightness factor that affected the V-shaped function was dark-adapted vs light-adapted viewing, that is, the chicks showed a slight shift away from red and/or a slightly more negative slope with light adaptation.
Horsepower requirements for high-solids anaerobic digestion

Improved organic loading rates for anaerobic bioconversion of cellulosic feedstocks are possible through high-solids processing. Additionally, the reduction in process water for such a system further improves the economics by reducing the overall size of the digestion system. However, mixing of high-solids materials is often viewed as an energy-intensive part of the process. Although the energy demand for high-solids mixing may be minimized by improving the agitator configuration and reducing the mixing speed, relatively little information is available for the actual horsepower requirements of a mechanically mixed high-solids digester system. The effect of sludge total solids content and digester fill level on mixing power requirements was evaluated using a novel NREL laboratory-scale high-solids digester. Trends in horsepower requirements are shown that establish the optimum parameters for minimizing mixing energy requirements, while maintaining adequate solids blending for biological activity. The comparative relationship between laboratory-scale mixing energy estimates and those required for scale-up systems is also established.
Image segmentation using Gibbs-Markov random fields based on bond percolation

This paper presents a new bond percolation base model to determine the clique potential parameters of a Gibbs-Markov model used in image segmentation. Previously, experimentally determined fixed values were used for these parameters which did not depend on the underlying image data. Using the proposed model, the clique potential parameters are now derived as a function of local characteristics of the image under consideration. The suitability of this approach to multiscale processing via application of the renormalization group transformation is also discussed.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Space-Charge Temporal Broadening Effects In Streak-Camera Tubes

An electron space-charge model has been developed that explains the temporal broadening effect in streak-camera tubes. The validity of the model is demonstrated for the Photochron I tube.
Specific Heat of Cerium and Europium Metals between 0.4 and 4°K

The specific heats of cerium and europium metals have been measured between 0.4 and 4\ifmmode^\circ\else\textdegree\fi{}K in a ${\mathrm{He}}^{3}$ cryostate. For cerium, two experiments were made with samples consisting of 62 and 39% of the $\ensuremath{\alpha}$ phase (fcc), the balance being $\ensuremath{\beta}$ cerium (hex). Due to a pronounced peak at 12.5\ifmmode^\circ\else\textdegree\fi{}K the specific heat is quite large already at 4\ifmmode^\circ\else\textdegree\fi{}K. A previously unknown flat anomaly in ${C}_{p}$ was found around 0.8\ifmmode^\circ\else\textdegree\fi{}K. By combining the present measurements with those of Parkinson and Roberts (3% of $\ensuremath{\alpha}$ cerium) and by assuming ${C}_{L}=0.612{T}^{3}$ and ${C}_{E}=10.5T$ (specific heats always given in mJ/mole\ifmmode^\circ\else\textdegree\fi{}K) for the lattice and electronic specific heats of the trivalent $\ensuremath{\beta}$ phase an analysis gave ${C}_{p}=x(0.50{T}^{3}+21T)+(1\ensuremath{-}x)(0.612{T}^{3}+10.5T+{C}_{M})$. Here $x$ is the fraction of $\ensuremath{\alpha}$ cerium in the sample and ${C}_{M}$ is the magnetic specific heat of the $\ensuremath{\beta}$ phase. ${C}_{E}$ is thus about twice as large for the quadrivalent $\ensuremath{\alpha}$ phase as for $\ensuremath{\beta}$ cerium. In the former modification ${C}_{M}=0$ because there is no magnetic $4f$ electron. Since all of the stable isotopes of cerium are even-even nuclei the nuclear specific heat ${C}_{N}=0$.Below 1.2\ifmmode^\circ\else\textdegree\fi{}K the specific heat of europium can be represented with 0.8% maximum deviation from experimental points by ${C}_{p}=27.96{T}^{3}+6.18T+2.333{T}^{\ensuremath{-}2}$. Above 1.2\ifmmode^\circ\else\textdegree\fi{}K the temperature dependence of ${C}_{M}$ gradually becomes less than ${T}^{3}$ and the results no longer can be expressed as a simple power law. This points to an anomaly in ${C}_{M}$, centered probably somewhere between 4 and 10\ifmmode^\circ\else\textdegree\fi{}K. As averages of two least-squares analyses we adopt ${C}_{E}=(5.8\ifmmode\pm\else\textpm\fi{}1.0)T$, ${C}_{N}=(2.36\ifmmode\pm\else\textpm\fi{}0.07){T}^{\ensuremath{-}2}$. ${C}_{E}$ is thus in between the values $\ensuremath{\sim}10.5T$ and $2.9T$ observed for many trivalent lanthanides and divalent ytterbium, respectively. Europium metal appears to be divalent and the ground state of ${\mathrm{Eu}}^{2+}$ ions is $^{8}S_{\frac{7}{2}}$. Since the orbital angular momentum of the $4f$ electrons is zero in an $S$ state, ${C}_{N}$ is rather small. The effective magnetic field at europium nuclei becomes ${H}_{\mathrm{eff}}=260\ifmmode\pm\else\textpm\fi{}4$ kG in excellent agreement with ${H}_{\mathrm{eff}}=264\ifmmode\pm\else\textpm\fi{}8$ kG deduced recently by Barrett and Shirley from M\"ossbauer measurements. Another interpretation of the experimental results, suggesting that europium at low temperatures might be a mixture of di- and trivalent phases, is also briefly discussed.
In-situ crack propagation in pressureless sintered fiber reinforced composites

Abstract Crack propagation in sintered SiC fiber reinforced alumina matrix composites was studied in situ inside a scanning electron microscope. Both crack front and crack wake toughening mechanisms were studied in isolation. In the crack front study, the crack propagation behavior varied with fiber coatings. For the uncoated fibers, a three-fold load increase was necessary to advance the crack over the fibers. A gradual load increase was necessary to propagate the crack over the fibers that were initially polymer coated. In samples where the fibers were either metal or polymer/metal coated, the crack becomes unstable before reaching the fiber positions and the fibers had no effect in resisting the crack propagation. However, the metal coated samples reached the highest toughness values during the crack wake study, with an increase in toughness of 75% over the monolithic samples. Crack profiles were measured and the crack opening displacements revealed direct evidence of the crack fiber interactions.
Triplet‐sensitized irradiation of a main‐chain liquid crystalline poly(aryl cinnamate) in three different phases

Visible light irradiation of thin films of a main-chain liquid crystalline poly(aryl cinnamate) using ketocoumarins as triplet sensitizers leads to photochemical crosslinking and UV-vis and FTIR spectroscopic changes associated with saturation of the cinnamate double bond, most likely by 2 + 2 photocycloaddition. The triplet sensitizers are themselves photolabile and are lost by photochemical reactions during the sensitization process. A new ketocoumarin sensitizer with decyloxy substituents and a reduced tendency to phase separate from the polymer is reported. A simple calculation of the sensitization stoichiometry shows that a single molecule of this ketocoumarin sensitizes the destruction of approximately 90 cinnamate chromophores in the “as cast” films below Tg and about 300 chromophores in the more-ordered glassy nematic films and in “as cast” films of poly(vinyl cinnamate). Triplet sensitization of fluid nematic films leads, upon initial irradiation, to UV-vis hyperchromism that is attributed to disruption of chromophore aggregation and, possibly, to disruption of the nematic mesophase as photoproducts begin to form. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 134–144, 2001
Enhanced Adhesion by Gecko-Inspired Hierarchical Fibrillar Adhesives

The complex structures that allow geckos to repeatably adhere to surfaces consist of multilevel branching fibers with specialized tips. We present a novel technique for fabricating similar multilevel structures from polymer materials and demonstrate the fabrication of arrays of two- and three-level structures, wherein each level terminates in flat mushroom-type tips. Adhesion experiments are conducted on two-level fiber arrays on a 12-mm-diameter glass hemisphere, which exhibit both increased adhesion and interface toughness over one-level fiber samples and unstructured control samples. These adhesion enhancements are the result of increased surface conformation as well as increased extension during detachment.
Asymmetric cross-sensitization to the locomotor stimulant effects of phencyclidine and MK-801

Chronic administration of a psychomotor stimulant has been shown to produce progressively enhanced effects, a phenomenon called "reverse tolerance" or sensitization. Sensitization which develops to the psychomotor stimulant effect of a drug generalizes to drugs with similar neurochemical mechanisms of action, a phenomenon called cross-sensitization. The present study compared the psychomotor stimulant effects of phencyclidine and MK-801, examined the effects of the daily injection of phencyclidine and MK-801 on locomotor activity and investigated whether reciprocal cross-sensitization occurred between phencyclidine and MK-801. Adult female Sprague-Dawley rats were used. Their locomotor activity was measured automatically for a 2 h period following drug injection. Phencyclidine and MK-801 both increased locomotor activity. Four daily injections of phencyclidine in a dose of 3.2 mg/kg i.p., or MK-801 in a dose of 0.32 mg/kg i.p., produced sensitization to locomotor activity. Moreover, MK-801 sensitized rats showed cross-sensitization to phencyclidine. However, phencyclidine sensitized rats did not show cross-sensitization to MK-801. This finding suggests that there are significant differences in the neurochemical mechanisms underlying phencyclidine-induced and MK-801-induced sensitization. Phencyclidine sensitization may not be mediated by NMDA receptors.
Symptomatic pancreatic polypeptide-secreting tumor of the distal pancreas (PPOMA)

Our report describes a 46-yr-old woman who presented with watery diarrhea in the presence of multiple endocrine neoplasia type I (MEN I) syndrome. Of various potential pancreatic endocrine hormones, only serum levels of pancreatic polypeptide were elevated. Radiologic imaging failed to identify a pancreatic tumor; her diarrhea was therefore managed with subcutaneous administration of somatostatin. Three years later she developed gallstone pancreatitis with the subsequent development of a pancreatic pseudocyst. At exploration for drainage of the pseudocyst, intraoperative ultrasound identified a 6-mm tumor in the distal pancreas that was resected. Final pathology documented a pancreatic endocrine tumor with immunohistochemical staining demonstrating the presence of pancreatic polypeptide. The present case illustrates the symptomatology that may be associated with pancreatic polypeptide-secreting endocrine tumors of the pancreas.