bluuebunny/crossref_metadata_2025 huggingface dataset:
Dirac and Lagrange Algebraic Constraints in Nonlinear Port-Hamiltonian Systems
Authors: van der Schaft Arjan , Maschke Bernhard
Published: June 2020

After recalling the definitions of standard port-Hamiltonian systems and their algebraic constraints, called here Dirac algebraic constraints, an extended class of port-Hamiltonian systems is introduced. This is based on replacing the Hamiltonian function by a general Lagrangian submanifold of the cotangent bundle of the state space manifold, motivated by developments in (Barbero-Linan et al., J. Geom. Mech. 11, 487–510, 2019) and extending the linear theory as developed in (van der Schaft and Maschke, Syst. Control Lett. 121, 31–37, 2018) and (Beattie et al., Math. Control Signals Syst. 30, 17, 2018). The resulting new type of algebraic constraints equations are called Lagrange algebraic constraints. It is shown how Dirac algebraic constraints can be converted into Lagrange algebraic constraints by the introduction of extra state variables, and, conversely, how Lagrange algebraic constraints can be converted into Dirac algebraic constraints by the use of Morse families.
Geochemical characterization of groundwater evolution south of Grand Canyon, Arizona (USA)
Authors: Beisner Kimberly R. , Solder John E. , Tillman Fred D. , Anderson Jessica R. , Antweiler Ronald C.
Published: June 2020

Better characterization of the geochemical evolution of groundwater south of Grand Canyon, Arizona (USA), is needed to understand natural conditions and assess potential effects from breccia-pipe uranium mining in the region. Geochemical signatures of groundwater at 28 sampling locations were evaluated; baseline concentrations for select trace elements (As, B, Ba, Cr, Li, Mo, Rb, Se, Sr, Th, Tl, U, V) were established, and anomalous chemistry characteristics were identified. Concentrations at some groundwater sites exceeded the USEPA drinking water standard for As of 10 μg/L (Red Canyon, Miners, JT, Havasu, and Warm Springs) and U of 30 μg/L (Salt Creek Spring). Four springs from the study area (Blue, Havasu, Fern, and Warm Springs) had unique chemistry, which may indicate a deep flow path or potential contribution of fluids from lower in the crust. Other springs in the study area were distinguished by major anion water type: sulfate, bicarbonate, and a mixture of the two. Water type distinctions were somewhat spatially segregated, with sulfate type present on the western side of the study area, bicarbonate type on the eastern side, and a mixture of the two interspersed between the endmember sites. Sulfate-type water from this study area had low strontium isotopic ratio (87Sr/86Sr) values. The location of spring discharge within single drainages of the Grand Canyon may influence chemistry, as groundwater discharging from bedrock was altered after flowing through alluvial material. Geochemical analysis of groundwater in Grand Canyon indicates the importance of continued monitoring and better understanding of short-term chemical fluctuations.
Proinflammatory Extracellular Vesicle-Mediated Signaling Contributes to the Induction of Neuroinflammation in Animal Models of Endotoxemia and Peripheral Surgical Stress
Authors: Fricke F. , Gebert J. , Kopitz J. , Plaschke K.
Published: June 2020

Peripheral inflammation induced by endotoxemia or surgical stress induces neuroinflammation thereby causing neurological symptoms ranging from sickness behavior to delirium. Thus, proinflammatory signaling must be operative between the periphery and the central nervous system (CNS). In the present study, we tested whether nanometer-sized extracellular vesicles (EVs) that were produced during the peripheral inflammatory process have the capacity to induce neuroinflammation. Conditions of endotoxemia or surgical intervention were simulated in rats by lipopolysaccharide (LPS) injection or partial hepatectomy (HpX). EVs were concentrated from these animals and tested for their proinflammatory action (I) in a microglial cell line and (II) by intracerebroventricular and (III) by intravenous injections into healthy rats. EVs from both conditions induced the secretion of cytokines from the glial cell line. Intracerebroventricular injection of the EVs caused the release of inflammatory cytokines to the cerebrospinal fluid indicating their pro-neuroinflammatory capacity. Finally, proinflammatory EVs were shown to pass the blood–brain barrier and induce neuroinflammation after their intravenous injection. Based on these data, we suggest that EV-associated proinflammatory signaling contributes to the induction of neuroinflammation in endotoxemia and peripheral surgical stress. Preliminary results suggest that peripheral cholinergic signals might be involved in the control of proinflammatory EV-mediated signaling from the periphery to the brain.
Tidal variation of total suspended solids over the Yangtze Bank based on the geostationary ocean color imager
Authors: Zhou Yu , Xuan Jiliang , Huang Daji
Published: June 2020

Hourly mapping by a Geostationary Ocean Color Imager was used to reveal the spatial pattern and tidal variation of total suspended solids (TSS) over the Yangtze Bank in the Yellow and East China Seas during the winter. The TSS form a tongue-shaped structure, which decreases further offshore in a stepwise manner. The stepwise change is separated by two fronts of TSS, which are located near the 20-m and 50-m isobaths. The tidal variation of TSS concentration during the study period is evident and can be divided into three stages: decay, maintenance, and growth. Compared with the relatively stationary TSS during the maintenance stage, drastic changes exist during the decay and growth stages. In terms of tide-induced mixing, the dynamic analysis shows that both the topography and the tidal currents play an important role in the spatio-temporal variation of TSS during the tidal period. In particular, spatial distribution is primarily determined by the topography, whereas the temporal variations in tidal scale are determined by the tidal currents.
Informed successive condition assessments in bridge maintenance
Authors: Honfi Dániel , Björnsson Ivar , Ivanov Oskar Larsson , Leander John
Published: June 2020

The condition assessment of bridges considers a combination of information from different sources rendering multiple levels of assessment possible. This paper illustrates how successive condition assessment strategies increase the expected utility compared to single choice decisions through Bayesian inference. Multiple levels of assessment allow for additional possibilities for obtaining structural health information and updating one’s beliefs about structural condition. Thus, more informed decision-making is possible with respect to the gain in accuracy versus the costs of the assessment options. The paper aims to introduce how the successive approach can be implemented and in which scenarios it provides an increase in expected utility in comparison to one instant decision. To highlight this, a few pedagogical numerical examples are provided.
The political economy of adult learning systems—some institutional features that promote adult learning participation
Authors: Desjardins Richard , Ioannidou Alexandra
Published: June 2020

Recent years have witnessed an increasing scholarly interest in the study of education, training, and skill formation from a comparative political economy perspective. The purpose of this article is to contribute to the emerging field of the political economy of adult learning systems, which seeks to understand the causes and consequences of cross-national diversity in adult learning systems. The article introduces this interdisciplinary research strand by reviewing recent work and different typologies that have emerged out of the field of comparative economics and comparative politics, which are relevant to the study of adult learning systems. The empirical evidence on cross-national patterns of organized adult learning drawn on PIAAC data suggests that existing typologies are insufficient to explain the cross-national patterns. The article discusses some specific institutional features that promote adult learning participation and points out conditions and policies that support effective adult learning systems.
Association between HDL-C levels and menopause: a meta-analysis
Authors: Li Hongwei , Sun Runlu , Chen Qian , Guo Qi , Wang Junjie , Lu Liming , Zhang Yuling
Published: June 2020

Purpose

Menopause modifies women’s lipid profiles. However, the fact that it is still unclear whether high-density lipoprotein-cholesterol (HDL-C) levels decrease in postmenopausal women necessitated a systematic review and meta-analysis.

Methods

The PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched and 498 articles published between 1987 and 2020 were retrieved. Studies reporting HDL-C, low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC), and triglyceride (TG) levels in both postmenopausal and premenopausal populations were included. The quality of the included studies was assessed using the Cross-Sectional/Prevalence Study Quality tool. The standard mean difference (SMD) and 95% confidence interval (CI) were estimated using random effects models. A meta-regression analysis and subgroup analysis were performed to identify potential modifiers. Egger’s test and funnel plots were constructed to evaluate publication biases.

Results

Lipid profiles from 18 cross-sectional studies and two cohort studies including 5652 postmenopausal women and 7825 premenopausal women were meta-analyzed. HDL-C levels were not significantly different between the postmenopausal and premenopausal women (SMD = − 0.053, 95% CI − 0.171 to 0.066, p = 0.383) and were not affected by country, publication year, study quality in the meta-regression analysis, or significant publication bias. Higher LDL-C, TC, and TG levels were detected in postmenopausal women than in premenopausal controls.

Conclusion

Unlike increased LDL-C, TC, and TG levels, HDL-C levels in pre- and postmenopausal women were not different in this first meta-analysis of lipid profiles in premenopausal and postmenopausal women. Prospective studies with large populations examining HDL-C levels and functions in women with different menopausal statuses are essential in the future.

Trial registration number

None.
Hydrolysis of corn stover pretreated by DESs with carbon-based solid acid catalyst
Authors: Hu Shuanglan , Meng Fei , Huang Dongting , Huang Junsheng , Lou Wenyong
Published: June 2020

This study evaluated two hydrolysis strategies that involve a two-step and a one-pot process for the hydrolysis of cellulose. The two-step process consisted of cellulose pretreatment with deep eutectic solvent, followed by hydrolysis promoted by the carbon-based solid acid catalyst. The obtained results showed that the xylose and glucose yields were 33.9% and 6.9%, respectively, from corn stover based on this two-step strategy with ChCl ·Formic acid used as the pretreatment solvent. For one-pot hydrolysis, side reactions occurred and less glucose accumulated in the reaction system. In this case, the maximum achieved glucose yield was 21.1% for the hydrolysis of microcrystalline cellulose.

Graphic abstract

The corn stover was pretreated with DES and then hydrolysed by carbon-based solid acid catalyst. Approximately 33.9% of xylose and 6.9% of glucose was recovered from corn stover with ChCl·Formic acid as the pretreatment solvent.
On the timescale at which statistical stability breaks down
Authors: Dobbs Neil , Korepanov Alexey
Published: June 2020

In dynamical systems, understanding statistical properties shared by most orbits and how these properties depend on the system are basic and important questions. Statistical properties may persist as one perturbs the system (
statistical stability
is said to hold), or may vary wildly. The latter case is our subject of interest, and we ask at what timescale does statistical stability break down. This is the time needed to observe, with a certain probability, a substantial difference in the statistical properties as described by (large but finite time) Birkhoff averages.

The quadratic (or logistic) family is a natural and fundamental example where statistical stability does not hold. We study this family. When the base parameter is of Misiurewicz type, we show, sharply, that if the parameter changes by

t

, it is necessary and sufficient to observe the system for a time at least of the order of

|t|^{−1}

to see the lack of statistical stability.
Entropy formula and continuity of entropy for piecewise expanding maps
Authors: Alves José F. , Pumariño Antonio
Published: June 2020

We consider some classes of piecewise expanding maps in finite dimensional spaces having invariant probability measures which are absolutely continuous with respect to Lebesgue measure. We derive an entropy formula for such measures and, using this entropy formula, we present sufficient conditions for the continuity of that entropy with respect to the parameter in some parametrized families of maps. We apply our results to a classical one-dimensional family of tent maps and a family of two-dimensional maps which arises as the limit of return maps when a homoclinic tangency is unfolded by a family of three dimensional diffeomorphisms.
Is energy expenditure reduced in obese mice with mutations in the leptin/leptin receptor genes?
Authors: Trayhurn Paul , Arch Jonathan R. S.
Published: June 2020

Rodents with mutations in the leptin, or leptin receptor, genes have been extensively used to investigate the regulation of energy balance and the factors that underlie the development of obesity. The excess energy gain of these mutants has long been considered as being due in part to increased metabolic efficiency, consequent to reduced energy expenditure, but this view has recently been challenged. We argue, particularly though not exclusively, from data on ob/ob mice, that three lines of evidence support the proposition that reduced expenditure is important in the aetiology of obesity in leptin pathway mutants (irrespective of the genetic background): (i) milk intake is similar in suckling ob/ob and +/? mice; (ii) ob/ob mice deposit excess energy when pair-fed to the ad libitum food intake of lean siblings; (iii) in several studies mutant mice have been shown to exhibit a lower RMR ‘per animal’ at temperatures below thermoneutrality. When metabolic rate is expressed ‘per unit body weight’ (inappropriately, because of body composition differences), then it is invariably lower in the obese than the lean. It is important to differentiate the causes from the consequences of obesity. Hyperphagic, mature obese animals weighing 2–3 times their lean siblings may well have higher expenditure ‘per animal’, reflecting the costs of being larger and of enhanced obligatory diet-induced thermogenesis resulting from the increased food intake. This cannot, however, be used to inform the aetiology of their obesity.
The under-reporting of sexual harassment in Australian workplaces: are organisational processes falling short?
Authors: MacDermott Therese
Published: June 2020

Sexual harassment is persistent, prevalent and under-reported in Australian workplaces despite its legal regulation over many decades. The most recent survey data in Australia indicate that the majority of individuals who are subject to sexual harassment at work do not make a formal report or lodge a complaint. The opportunity for voice that organisational processes provide to those who experience sexual harassment at work is a particular focus, given the under-reporting problem. The paper also considers the impact of organisational processes on those who observe the inappropriate behaviour and/or the organisational response. Ultimately, this paper argues that organisations should reduce their reliance on individual complaints by expanding the pathways by which concerns can be raised or observed behaviours addressed that offer alternative voice mechanisms, with an emphasis on problem-solving and early intervention where this is appropriate. The paper also considers different communications strategies, such as approaches to training, the sharing of information about workplace incidents, and leadership on the issue within organisations.
Tropical cycles
Authors: Northshield S.
Published: June 2020

The Lyness equation
(1)
\begin{equation}{X_{n + 1}} = \frac{{{X_n} + a}}{{{X_{n - 1}}}},\,(a,{x_1},{x_2} > 0)\end{equation}

was introduced in 1947 by Lyness [1] and it, and related equations, have long been studied; see [1, 2, 3, 4, 5, 6, 7] and references therein. Perhaps surprisingly, all solutions of (1) are bounded (i.e. for all x1, x2, the set {xn} is bounded) - we will show that below. Furhter, there often exist periodic solutions (i.e. xn = xn+N for all n in which case we say that (xn) has period N). See [8] for a discussion of which periods are possible for a given α. We note that a sequence of period, say, 5 also has periods 10, 15, 20, …. so we use the term minimal period for the smallest positive N such that xn = xn+N for all n.
Two plane geometry problems approached through analytic geometry
Authors: Hamzić Dina Kamber , Šabanac Zenan
Published: June 2020

Geometry is a very interesting, applicable and beautiful part of mathematics. However, geometry is often difficult for students to understand and demanding for teachers to teach [1]. Constructing proofs in geometric problems turns out to be particularly difficult, even for high attaining students [2]. Sometimes, students do not even know where to start when trying to solve these [3].
New approaches to neorealism in Italian cinema
Authors: Garofalo Damiano
Published: June 2020

In an article with the challenging title ‘Against Realism’, Alan O'Leary and Catherine O'Rawe (2011) argued that Italian cinema studies needed to move forward. In their view, the abuse of ‘realism’ as a prescriptive as well as descriptive term had stunted research into Italian cinema of the postwar period, channelling it exclusively towards neorealist trends and thus devaluing study of the other forms, movements, auteurs and productions that emerged during the same period. This historiographical tendency, which Christopher Wagstaff aptly called the ‘institution of neorealism’ (2007, 37), encouraged the development of reverential study and by the 1960s had assumed the form of a canon. While the position taken by O'Leary and O'Rawe was certainly provocative, it has served to stimulate thinking about the areas of postwar Italian cinema that had remained in the shadows and unexplored. Starting to focus on an ‘other’ cinema has not had to mean ‘forgetting’ neorealism, but has brought changes to the way that it is studied. Almost ten years later, the challenge seems to be to rethink neorealism as a transnational phenomenon that straddles different periods, genres and contexts; while it has its roots in postwar European culture, it continues to be influential on a global level.
“This Battle Started Long Before Our Days …” The Historical and Political Context of the Russo-Turkish War in Russian Popular Publications, 1877–78
Authors: Parppei Kati
Published: June 2020

Popular publications produced in Russia on the events in the Balkans in 1877–78 offer a valuable opportunity to examine how the historical and political background of the Russo-Turkish War was conveyed to common readers, some of whom were potentially involved in the military action, or persuaded to support the cause by other means. The conceptions produced and distributed in these booklets were firmly based on pan-Slavistic ideas of Russians’ duty to help their “Slavic brothers.” The publications presented the reader with propagandistic images of Turkish enemies, which were compared to Islamic enemies of the Russian national narrative. The result was persuasive and simplified imagery leaning on dualistic representations of ethnic groups and graphic depictions of violence, effectively justifying Russia’s involvement in the events and taking a stand in the internal issues concerning Muslim minorities, too.
The impact of acute changes of inflammation on appetite and food intake among older hospitalised patients
Authors: Pourhassan Maryam , Sieske Lars , Janssen Gregor , Babel Nina , Westhoff Timm Henning , Wirth Rainer
Published: June 2020

The present study aimed to investigate the effect of acute changes in serum C-reactive protein (CRP) on appetite and food intake among older hospitalised patients. A total of 200 patients (age range 65–94 years, 62·5 % women) participated in this prospective longitudinal observational study. Risk of malnutrition was measured according to the Mini Nutritional Assessment Short Form. The Simplified Nutritional Appetite Questionnaire (SNAQ) and Edmonton Symptom Assessment System (ESAS) were used to evaluate patients’ appetite at the time of hospital admission (baseline) and after 7 d (follow-up). Food intake was measured according to the plate diagram and serum CRP was analysed at baseline and follow-up. At baseline, 30·5 % of the patients had moderate to severe inflammation, 31·0 % were malnourished and 48·0 % had food intake <75 % of the meals offered. Also, 32·5 and 23·5 % reported poor and very poor appetite or severe loss of appetite according to the SNAQ and ESAS, respectively. Of the patients, 40 % displayed a pronounced reduction in median CRP levels by −1·2 mg/dl and 19 % demonstrated an increase in median CRP levels by +1·2 mg/dl. Appetite significantly improved (P = 0·006) in patients with a decrease in CRP level and deteriorated in those with an increase in CRP level (P = 0·032). Changes in CRP levels did not show any significant impact on food intake. In a regression analysis, changes of inflammation were the major independent predictor for changes of patients’ appetite. We conclude that inflammation has a significant impact on appetite and should therefore be considered in the diagnosis and treatment of malnutrition.
TWO NOTES ON THE NEW CROESUS EPIGRAM FROM THEBES
Authors: Simonton Matthew
Published: June 2020

In March 2005 a rescue excavation uncovered a spectacular new epigraphic find from Thebes. Now on display in the Archaeological Museum of Thebes, a column drum 0.41 m in height has inscribed on it two identical epigrams, one (the older one) written vertically in Boeotian script and a second (later) Ionian copy written horizontally on the other side. Nikolaos Papazarkadas published theeditio princepsof the epigram in 2014, using both inscriptions to create a composite text. As Papazarkadas realized, the column drum, which has a chi-shaped orifice at one end meant to hold a stationary object, at one point displayed a ‘shining shield’ (φαεννὰν | [ἀσπ]ίδα, lines 3–4) that Herodotus had seen in the temple of Apollo Ismenius in Thebes. Moreover, this shield was interpreted by Herodotus (relying on the language of the inscription and likely on the commentary of temple staff) as having been dedicated by the Lydian king Croesus to the hero Amphiaraus, when he was ‘testing’ the various oracles in Greece in order to decide on a course of action against his rival Cyrus of Persia.
Not all obligatory control is movement
Authors: BAYKOV FYODOR , RUDNEV PAVEL
Published: June 2020

This squib presents two challenges for the analysis of promise-type verbs within the Movement Theory of Control. We show that the objects of these verbs in Russian are not prepositional and are incorrectly predicted to be legitimate controllers. We also argue against analysing oblique control as movement.
Pathogenesis of Human Hair Defects
Authors: Porter P.S. , Aoyagi T. , Matta R.
Published: June 2020

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.
Scanning and Transmission Electron Microscopy of Human Lung in a Patient with Sarcoid-like Reaction
Authors: Watson John H. L. , Goodwin Jessica , Coates E. Osborne
Published: June 2020

Biopsies of lung were taken at operation from a patient with semi-acute diffuse pulmonary infiltrates for study by TEM and SEM. Tissue by light microscopy showed non-caseating granulomas consistent with sarcoidosis. Clinical evidence suggested a hypersensitivity reaction related to inhalation of substance of undetermined nature. Samples were fixed in glutaraldehyde, cacodylate-buffered. They were critical point dried and coated with Au-Pd for SEM, and were handled appropriately for TEM in Araldite. Sections were contrasted with uranyl acetate and lead citrate.
Cellular Changes in the Canine Parathyroid Following Pancreatectomy
Authors: Nordquist R.E. , Palmieri G.M.A. , Phillips R.H. , Hartsuck J.M. , Volling N.I.
Published: June 2020

In 1935, Houssay described the relationship of the pancreas and the parathyroid; his histological studies demonstrated that pancreatectomy induced rapid and characteristic cellular alternations in the parathyroid. The present investigation was designed to study the ultrastructure and physiology of this induced change of parathyroid architecture.
Toward a Better Understanding of 3-Dimensional Cell Structure Utilizing High Voltage Electron Microscopy
Authors: Paulin Jerome J.
Published: June 2020

High voltage microscopy combined with stereoscopic photography of material embedded in epon-araldite and thick sectioned can be effectively utilized in studying complex organellar systems. The spatial distribution of the subpellicular and flagellar microtubules found in species of the Trypanosomatidae (Phylum Protozoa, class Zoomastigophorea) and their unique labyrinthine mitochondrial-kinetoplast complex lend themselves to this analysis.

Figure 1 is a stereo-pair of a 0.5μM section (thicknesses are approximations based on interference colors) through the anterior portion of the cell body and flagellum of Trypanosoma equiperdum. Profiles of the subpellicular microtubules in both transverse and longitudinal orientation are observed. The dense plaques which form the attachment sites between the flagellum and cell body can be depicted. The arms on the A microtubules of the flagellar axoneme and a ring of dense bodies around the central pair of axonemal microtubules are resolvable in thick sections. Tilting of the specimen (± 5° from the horizontal axis) reveals the crystalline-like structure of the paraxial rod found in juxtaposition to the flagellar axoneme.
Association of β-Glucan Synthetases with Plant Plasma Membranes: Quantitative Electron Microscopy as an Aid to Enzyme Localization in Cell Fractionation
Authors: VanDerWoude W. J. , Morré D. James
Published: June 2020

Phosphotungstic acid - chromic acid (PTA-CrO3), an electron-dense stain specific for plant plasma membranes, has made possible the identification and purification of this cell component in isolated membrane fractions. In studies of plant cell wall biogenesis, localization of β-glucan synthetases by in vitro assay of membrane fractions has shown their association with dictyosome-rich fractions when assayed at low (1 to 5 μM) UDP-glucose concentrations. However, when assayed at 1 mM UDP-glucose, plasma membrane-rich fractions from onion stem synthesized β-glucans most actively. Glucans synthesized were primarily β,1-4 at low substrate concentrations and primarily β,1-3 at 1 mM UDP-glucose. Analysis of glucolipid synthesis by both membrane fractions indicated that at low substrate concentrations competition for substrate for the synthesis of sterol glucosides was responsible for relatively low β-glucan synthesis by plasma membranes.
Preparation of Live Mammalian Cells for Direct Observation in the Electron Microscope
Authors: Lyon Norman C. , Parsons Donald F.
Published: June 2020

Mammalian cells (bovine spermatozoa, 3T3, melanoma, Erhlich ascites tumor) have been observed, unfixed and in the wet state in the electron microscope in this laboratory although intracellular details (filaments, nuclei, mitochondria, melanin granules) were resolved, cytoplasmic streaming or cell movement indicative of cell viability, were not observed. Tighe et al have also failed to report signs of movement in their differentially pumped chamber. However, others have reported the survival of bacteria after exposure to the beam in the electron microscope, with cell movement during observation. Early work in this laboratory employed a water-vapor saturated atmosphere of helium and oxygen @ 200 Torr within the hydration chamber (E.M.C.) and with careful manipulation, the cells were never exposed to a relative humidity below 99%.
Cosmic Ray Particle Tracking in Selected Biological Tissues Flown on Apollo 17
Authors: Philpott D. E. , Turnbill C. , Corbett R.
Published: June 2020

One of the problems encountered during deep space flight by space travelers is penetrating cosmic radiation. Since cosmic rays travel singly and in random directions, a method was needed to locate the cells through which they traverse in order to study their effect. Detectors made up of alternate layers of cellulose and Lexan polycarbonate, which are capable of recording charged particles, were used in order to: span the desired range of interest Ƶ ≥ 6, be implanted under the scalp of flight animals, allow for very long exposure times, and allow for separation and identification of charged particles. This type of detector system has, in part, been used on the Apollo flights since Apollo 11 and at the Berkeley Bevatron.
Effect of Short-Term Hypertension on Rat Aortic Endothelial Surface Topography
Authors: Katora M. , Mauer C. , Hollis T.
Published: June 2020

In recent years many histological and transmission electron microscopic studies have been conducted on aortic tissue of animals rendered hypertensive via many procedures, with the specific intent of examining mechanisms responsible for increased transmural permeability consistently observed in these hypertensive models. To our knowledge, the present investigation represents the first study in which such an investigation has been extended to examination of the endothelial surface of aortas from hypertensive models employing scanning electron microscopy.

Male, Wistarrats, 300 g body weight, were rendered hypertensive by complete ligation of the abdominal aorta between origins of the renal arteries. This was accomplished via ventromedial laparotomy performed under ether anesthesia. Sham operated (laparotomy without aortic coarctation) and unoperated control animals were also used. Following a postoperative interval of 2 days, blood pressure was measured through direct carotid artery cannulation, and animals were then sacrificed through ether overdosing.
Influence of Calcium Ions on the Plant Cell Surface: Membrane Fusions and Conformational Changes
Authors: Morré D. James , Bracker Charles E. , VanDerWoude William J.
Published: June 2020

Calcium ions in the concentration range 5-100 mM inhibit auxin-induced cell elongation and wall extensibility of plant stems. Inhibition of wall extensibility requires that the tissue be living; growth inhibition cannot be explained on the basis of cross-linking of carboxyl groups of cell wall uronides by calcium ions. In this study, ultrastructural evidence was sought for an interaction of calcium ions with some component other than the wall at the cell surface of soybean (Glycine max (L.) Merr.) hypocotyls.
Crystalloid Inclusions in Hepatocyte Mitochondria and Their Similarity to Cytoplasmic Crystalloids
Authors: Minick Odell T. , Yokoo Hidejiro
Published: June 2020

Mitochondrial alterations were studied in 25 liver biopsies from patients with alcoholic liver disease. Of special interest were the morphologic resemblance of certain fine structural variations in mitochondria and crystalloid inclusions. Four types of alterations within mitochondria were found that seemed to relate to cytoplasmic crystalloids.

Type 1 alteration consisted of localized groups of cristae, usually oriented in the long direction of the organelle (Fig. 1A). In this plane they appeared serrated at the periphery with blind endings in the matrix. Other sections revealed a system of equally-spaced diagonal lines lengthwise in the mitochondrion with cristae protruding from both ends (Fig. 1B). Profiles of this inclusion were not unlike tangential cuts of a crystalloid structure frequently seen in enlarged mitochondria described below.
Renilla Bioluminescence: A Morphologic Approach to the Location of Photocytes
Authors: Spurlock Ben O. , Cormier Milton J.
Published: June 2020

The phenomenon of bioluminescence has fascinated layman and scientist alike for many centuries. During the eighteenth and nineteenth centuries a number of observations were reported on the physiology of bioluminescence in Renilla, the common sea pansy. More recently biochemists have directed their attention to the molecular basis of luminosity in this colonial form. These studies have centered primarily on defining the chemical basis for bioluminescence and its control. It is now established that bioluminescence in Renilla arises due to the luciferase-catalyzed oxidation of luciferin. This results in the creation of a product (oxyluciferin) in an electronic excited state. The transition of oxyluciferin from its excited state to the ground state leads to light emission.
Electron Microscopic Autoradiography of DNA, RNA and Collagen Synthesis on Cutaneous Wounds Following Calcitonin
Authors: Lupulescu A. , Habowsky J. E. , Milkintas J.
Published: June 2020

Improved methods provide the investigators with a better study and visualization of the hormone action at the cellular level in experimental and pathological conditions. Calcitonin was found to stimulate the fibroblast proliferation and collagen synthesis in experimental wounds of adult rabbits '. In order to study the intimate mechanism of calcitonin on cell metabolisms, such as, RNA, DNA and collagen synthesis, we used adult rabbits with experimental cutaneous wounds, 14 days after the wound induction (two linear incisions of 2 cm long under anesthesia). For electron microscopic autoradiography, eighteen rabbits were injected i.m. with synthetic salmon calcitonin (SCT), a dose of 64 MRCU (Medical Research Council Units) every other day for 14 days. Another eighteen rabbits served as controls.
Platinum Compounds as Stains for Electron Microscopy
Authors: Aggarwal S. K. , McAllister P. , Wagner R. W. , Rosenberg B.
Published: June 2020

Uranyl acetate has been used as an electron stain for en bloc staining as well as for staining ultrathin sections in conjunction with various lead stains (Fig. 1). Present studies reveal that various platinum compounds also show promise as electron stains. Certain platinum compounds have been shown to be effective anti-tumor agents. Of particular interest are the compounds with either uracil or thymine as one of the ligands (cis-Pt(II)-uracil; cis-Pt(II)-thymine). These compounds are amorphous, highly soluble in water and often exhibit an intense blue coloration. These compounds show enough electron density to be used as stains for electron microscopy. Most of the studies are based on various cell lines (human AV, cells, human lymphoma cells, KB cells, Sarcoma-180 ascites cells, chick fibroblasts and HeLa cells) while studies on tissue blocks are in progress.
Physical Assay of Purified Viruses, Particularly the Small Ones
Authors: Sharp D. Gordon
Published: June 2020

The assay of virus in water is a matter of present concern to those who seek to preserve a healthy environment. Bioassay, in terms of plaque forming units, can be made more meaningful if supplemented by physical assay of both total number and state of aggregation of the virions in suspension but most methods for preparation of suspended particles for electron microscopy induce aggregation. The drying process is usually responsible for this so it is desirable to make the preparation for microscopy without drying any liquid containing virus upon the preparation to be examined. This can be done by sedimentation methods already in use but these become difficult and cumbersome for very small viruses, particularly those of the enteric group usually found in water. However, it is just these that diffuse most rapidly and the excellent paper of Valentine and Allison (1) demonstrated that the rate of attachment of freely diffusing virions to an aluminized surface is accurately predictable if certain conditions are controlled. Figure 1 shows a simple device for doing this.
In situ Studies Using the High Voltage Electron Microscope
Authors: Swann P. R.
Published: June 2020

The recent availability of high voltage microscopes with their increased specimen penetration and their large working volume in the specimen region has stimulated new attempts to carry out in situ experiments. The thicker specimens which can now be used behave more like bulk material and the large working volume simplifies the design and construction of the special specimen stages required. In most high voltage microscopes several objective pole piece configurations are available but for in situ work the wide gap side entry is preferred because one of the tilt requirements is satisfied in a simple manner by rotating the specimen rod about its axis. Furthermore, tilting about the transverse axis can be achieved by operating a micrometer drive through the nose of the specimen rod thereby leaving the rest of specimen rod free for transmitting services such as cooling and heating to the specimen.
Electron Microscopy and Electron Diffraction of Hydrated Biological Material
Authors: Hui S.W. , Parsons D.F.
Published: June 2020

The importance of electron microscopy and electron diffraction of hydrated biological material needs no stress. The diffraction patterns of wet and stained catalase obtained at this laboratory shows that the fine structure of the protein crystal is destroyed by the usual drying and staining processes. The different phase transition behaviors of wet and dry phospholipid bilayers, as studied by electron diffraction, illustrates the necessity of studying the biological material in a more physiological state. Cell surface polysaccharides can be studied by electron microscopy only if they are preserved in a wet environment. An ultimate achievement of the hydration stage work would be visualization of living processes in an electron microscope.
Some Biological Applications of High Voltage Electron Microscopy
Authors: Ris Hans
Published: June 2020

The High Voltage Electron Microscope Laboratory at the University of Wisconsin has been in operation a little over one year. I would like to give a progress report about our experience with this new technique. The achievement of good resolution with thick specimens has been mainly exploited so far. A cold stage which will allow us to look at frozen specimens and a hydration stage are now being installed in our microscope. This will soon make it possible to study undehydrated specimens, a particularly exciting application of the high voltage microscope.

Some of the problems studied at the Madison facility are: Structure of kinetoplast and flagella in trypanosomes (J. Paulin, U. of Georgia); growth cones of nerve fibers (R. Hannah, U. of Georgia Medical School); spiny dendrites in cerebellum of mouse (Scott and Guillery, Anatomy, U. of Wis.); spindle of baker's yeast (Joan Peterson, Madison) spindle of Haemanthus (A. Bajer, U. of Oregon, Eugene) chromosome structure (Hans Ris, U. of Wisconsin, Madison). Dr. Paulin and Dr. Hanna are reporting their work separately at this meeting and I shall therefore not discuss it here.
The Asymmetry of Membranes and its Implications for Membrane Biogenesis
Authors: Singer S. J.
Published: June 2020

The fluid mosaic model of membrane structure is now accepted as a general scheme for the organization of the proteins and lipids of membranes. In this model, there are two classes of proteins associated with membranes, peripheral and integral. The integral proteins are postulated to be globular amphipathic molecules which, either singly or as subunit aggregates are embedded by their hydrophobic ends into a fluid matrix of lipid bilayer. The molecule may be embedded only part way through the bilayer, or if it has the appropriate size and structure, it may span the membrane with two different hydrophilic ends protruding from the two membrane surfaces, and a hydrophobic middle region embedded in the membrane interior. It is proposed that peripheral proteins are bound to the membrane at the exposed portions of specific integral proteins. Examples of each of these types of membrane proteins are known.
Plasma Membrane Biogenesis
Authors: Barrnett Russell J.
Published: June 2020

This report presents two examples of plasma membrane biogenesis in which the synthesis and assembly of components, phospholipid and enzyme proteins, were studies by a combination of biochemistry, cytochemistry and electron microscopy. These were: the proliferation of Schwann cell plasma membrane during the process of myelination of the trigeminal nerve in neonatal rats and amplification of the plasma membrane at the lateral and basal borders of secretory cells of the ducklings' salt gland as a result of salt stress.

In the study concerning myelination a method for the ultrastructural localization of acyltransferase activities (the first two steps in phospholipid synthesis) was applied to the developing rat trigeminal nerve. Determination of acyltransferase levels in the nerve indicated that a peak of activity occurs at the 8th day after birth with gradual declines of activity up to 15 days. This peak coincided with the peak of a-glycerophosphate incorporation into phospholipids in the microsome fraction of the nerve: wheras, no incorporation was noted in the myelin fraction.
Criteria and Methods for Reliable Three-Dimensional Image Reconstruction
Authors: Crowther R. A.
Published: June 2020

The reconstruction of a three-dimensional image of a specimen from a set of electron micrographs reduces, under certain assumptions about the imaging process in the microscope, to the mathematical problem of reconstructing a density distribution from a set of its plane projections.

In the absence of noise we can formulate a purely geometrical criterion, which, for a general object, fixes the resolution attainable from a given finite number of views in terms of the size of the object. For simplicity we take the ideal case of projections collected by a series of m equally spaced tilts about a single axis.
Practical Picture Processing
Authors: Welton T. A.
Published: June 2020

Various authors have emphasized the spatial information resident in an electron micrograph taken with adequately coherent radiation. In view of the completion of at least one such instrument, this opportunity is taken to summarize the state of the art of processing such micrographs. We use the usual symbols for the aberration coefficients, and supplement these with £ and 6 for the transverse coherence length and the fractional energy spread respectively. He also assume a weak, biologically interesting sample, with principal interest lying in the molecular skeleton remaining after obvious hydrogen loss and other radiation damage has occurred.
The Study of Single Heavy Atom Motion in the STEM
Authors: Langmore J. P. , Isaacson M. S. , Crewe A. V.
Published: June 2020

The observation of single atoms in the electron microscope has potential application to the localization of chemical sites in biological molecules and to the study of chemisorption. Before such use can be made, however, the interactions among the atoms, the surface and the electron beam must be better understood.

Of primary concern is the bond which the single heavy atoms make with the specimen. To what and how strongly are the heavy atoms bound? How may these bonds be disrupted? If the binding energy of an adsorbed atom to a surface is EB, in general the activation energy needed to move it one step along the surface (E*m) is between 0.1 and 0.5 EB.
Image Reconstruction Applied to High Voltage Microscopy
Authors: Johnson D. E. , Pfeifer J.
Published: June 2020

Greatly increased specimen penetration, which is the principle advantage of high voltage electron microscopy, carries with it an increased need for techniques to interpret the large amount of three-dimensional information projected into two-dimensional micrographs. Stereo views can provide very useful information and are widely used. However, for the general specimen, stereo views are limited in their ability to produce quantitative results. At the high voltage microscope facility, Univ. of Wisconsin, we have begun a program to develop and apply three dimensional reconstruction techniques to the microscopy of thick specimens.
A Magnetic Spectrometer for a Scanning Transmission Electron Microscope
Authors: Kosiara A. , Wiggins J. W. , Beer M.
Published: June 2020

A magnetic spectrometer to be attached to the Johns Hopkins S. T. E. M. is under construction. Its main purpose will be to investigate electron interactions with biological molecules in the energy range of 40 KeV to 100 KeV. The spectrometer is of the type described by Kerwin and by Crewe Its magnetic pole boundary is given by the equation

where R is the electron curvature radius. In our case, R = 15 cm. The electron beam will be deflected by an angle of 90°. The distance between the electron source and the pole boundary will be 30 cm. A linear fringe field will be generated by a quadrupole field arrangement. This is accomplished by a grounded mirror plate and a 45° taper of the magnetic pole.
Element Analysis of Microarea with Electron Microscope
Authors: Kokubo Yasushi , Koike Hirotami , Someya Teruo
Published: June 2020

In recent years, X-ray elemental analysis of specimen microareas has been widely carried out, using an electron microscope fitted with a solid state detector, i.e., an energy dispersive type spectrometer. With this method, it is very difficult to detect light elements, especially those present in thin specimens used for electron microscopy, because the X-ray yield for light elements is extremely small. And in the microarea range of 1000 Å or less, it is very difficult to obtain accurate values, owing to the diffusion of X-rays in the specimen. Although element analysis by Auger spectroscopy is reportedly promising for light elements, this method requires large probe currents of the order of 10−8 A or more. Thus, so long as an ordinary thermal electron cathode is used, this method allows analysis of only microareas measuring lp or more, due to the low brightness of the electron gun.
The Anomalous Rheed Patterns Observed from Ag-(111)Cu Bilayers
Authors: Horng C. T. , Vook R. W.
Published: June 2020

Very smooth (111) single crystal Cu films (1200Å) were evaporated on NaCl/mica in an ultra-high vacuum RHEED system at residual gas pressures of less than 1×10−8 torr. These Cu films served as substrates for thin epitaxial monolayer Ag overgrowth. Film thicknesses were measured by a quartz thickness monitor. These Ag-(111)Cu bilayer films were formed and examined in-situ in the RHEED system and subsequently by TEM.
Cross-Slip from Octahedral Onto Cube Planes in Ni3Al
Authors: Oblak J. M. , Rand W. H.
Published: June 2020

Slip in Ni3Al takes place primarily upon close-packed <111> planes by the motion of paired a/2dislocations, although slip can also be initiated upon cube planes at temperatures above 700°K (1,2). Because the antiphase boundary energy is at a minimum on <001> (3), a net reduction of energy is possible if such paired dislocations cross-slip from octahedral onto cube planes. The likelihood of this cross-slip event plays an important role in the theories on the flow stress of Ni3Al (1,2). Observations reported previously(h)demonstrate that cross-slip takes place at 1030°K. This investigation represents a more thorough exploration of its temperature range of occurrence.