bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing and evaluating predictive conveyor belt wear models
Authors: Webb Callum , Sikorska Joanna , Khan Ramzan Nazim , Hodkiewicz Melinda
Published: June 2020

Conveyor belt wear is an important consideration in the bulk materials handling industry. We define four belt wear rate metrics and develop a model to predict wear rates of new conveyor configurations using an industry dataset that includes ultrasonic thickness measurements, conveyor attributes, and conveyor throughput. All variables are expected to contribute in some way to explaining wear rate and are included in modeling. One specific metric, the maximum throughput-based wear rate, is selected as the prediction target, and cross-validation is used to evaluate the out-of-sample performance of random forest and linear regression algorithms. The random forest approach achieves a lower error of 0.152 mm/megatons (standard deviation [SD] = 0.0648). Permutation importance and partial dependence plots are computed to provide insights into the relationship between conveyor parameters and wear rate. This work demonstrates how belt wear rate can be quantified from imprecise thickness testing methods and provides a transparent modeling framework applicable to other supervised learning problems in risk and reliability.
Disaster Literacy and Public Health: A Systematic Review and Integration of Definitions and Models
Authors: Çalışkan Cüneyt , Üner Sarp
Published: June 2020

Objective:

The aim of this study is to develop an integrated definition and a conceptual model covering the dimensions of disaster literacy.

Methods:

A systematic literature review was conducted to identify the definitions and conceptual frameworks of disaster literacy. The content analysis of definitions and conceptual frameworks were conducted to identify the central dimensions of disaster literacy and to develop an integrated model.

Results:

In this study, 8 disaster literacy definitions and 4 conceptual model studies related to disasters were found. In line with these studies, a comprehensive definition of disaster literacy was presented. In addition, based on content analysis, a 16-matrix integrative conceptual model of the mitigation, preparedness, response and recovery dimensions of disaster literacy, and the access, understanding, appraisal, and application areas of disaster information processing were developed.

Conclusions:

In this study, a comprehensive definition and conceptual framework of disaster literacy were presented in an integrated model. By using this model, practices that are special to the phases of a disaster can be identified and supported in society. In addition, the model can contribute to empirical studies by providing the basis for the development of tools to measure disaster literacy.
Pediatric Emergency Department Responses to COVID-19: Transitioning From Surge Preparation to Regional Support
Authors: Hartford Emily A. , Keilman Ashley , Yoshida Hiromi , Migita Russell , Chang Todd , Enriquez Brianna , Liu Deborah R.
Published: June 2020

In the midst of a global pandemic, hospitals around the world are working to meet the demand for patients ill with the 2019 coronavirus disease (COVID-19) caused by the novel coronavirus first identified in Wuhan, China. As the crisis unfolds, several countries have reported lower numbers as well as less morbidity and mortality for pediatric patients. Thus, pediatric centers find themselves pivoting from preparing for a patient surge to finding ways to support the regional response for adults. This study describes the response from 2 West Coast freestanding academic children’s hospitals that were among the first cities in the United States impacted during this pandemic.
INTERPRETABILITY LOGICS AND GENERALISED VELTMAN SEMANTICS
Authors: MIKEC LUKA , VUKOVIĆ MLADEN
Published: June 2020

We obtain modal completeness of the interpretability logics IL
$\!\!\textsf {P}_{\textsf {0}}$
and ILR w.r.t. generalised Veltman semantics. Our proofs are based on the notion of full labels [2]. We also give shorter proofs of completeness w.r.t. the generalised semantics for many classical interpretability logics. We obtain decidability and finite model property w.r.t. the generalised semantics for IL
$\textsf {P}_{\textsf {0}}$
and ILR. Finally, we develop a construction that might be useful for proofs of completeness of extensions of ILW w.r.t. the generalised semantics in the future, and demonstrate its usage with
$\textbf {IL}\textsf {W}^\ast = \textbf {IL}\textsf {WM}_{\textsf {0}}$
.
Late Intermediate Period Plant Use at a Colla Hillfort, Puno, Peru (AD 1300–1450)
Authors: Langlie BrieAnna S.
Published: June 2020

In the Lake Titicaca Basin during the Late Intermediate period (LIP; AD 1100–1450), people's lives were overwhelmingly structured by warfare. Previous research in the region has shed light on how martial conflict between and possibly among competing ethnic groups motivated people to live in fortified villages on defensive hilltops. At the same time, there was a centuries-long drought that threatened agricultural production. Little is known about the plant use of people living in hillforts during this arduous time. Drawing on macrobotanical information collected from Ayawiri, one of the largest hillforts in the northern Titicaca Basin, I argue that the food stuffs and plants used were locally grown. Additionally, these findings indicate a possible departure from earlier symbolically charged and ritually important plant consumption practices based on the lack of imported maize. This research sheds light on how people adapted their domestic and agricultural strategies to warfare and climate change during the LIP.
A family of discrete spirals
Authors: Crilly Tony
Published: June 2020

Most spirals are continuous spirals, certainly those famous in history such as the traditional Archimedean spiral (r = a + bθ) and the logarithmic spirals (r = aebθ. Here we consider ‘discrete spirals’.
A spiral pattern investigation: making mathematical connections
Authors: Calleja James
Published: June 2020

Nowadays there is considerable agreement among educators that learning mathematics fundamentally involves making mathematics [1]. Students learn mathematics while working on tasks that they consider meaningful and worthwhile, and their interest is aroused when they can see the point of what they are being asked to do. Given that learning mathematics involves a process of meaning-making - the use of mathematical language, symbols and representations as learners negotiate ideas – activities should provide students with a variety of challenging experiences through which they can actively construct mathematical meanings for themselves.
New pancake series for π
Authors: Saouter Yannick
Published: June 2020

In [1], Dalzell proved that
$\pi = \frac{{22}}{7} - \int_0^1 {\frac{{{t^4}{{(1 - t)}^4}}}{{1 + {t^2}}}}$
. He then used this equation to derive a new series converging to π. In [2], Backhouse studied the general case of integrals of the form
$\int_0^1 {\frac{{{t^m}{{(1 - t)}^m}}}{{1 + {t^2}}}dt}$
and derived conditions on m and n so that they could be used to evaluate π. As a sequel, he derived accurate rational approximations of π. This work was extended in [3] where new rational approximations of π are obtained. Some related integrals of the forms
$\int_0^1 {\frac{{{t^m}{{(1 - t)}^m}}}{{1 + {t^2}}}P(t)\,dt}$
and
$\int_0^1 {\frac{{{t^m}{{(1 - t)}^m}}}{{\sqrt {1 - {t^2}} }}P(t)dt}$
with P(t) being of polynomial form are also investigated. In [4] the author gives more new approximations and new series for the case m = n = 4k. In [5] new series for π are obtained with the integral
$\int_0^a {\frac{{{t^{12m}}{{(a - t)}^{12m}}}}{{1 + {t^2}}}dt}$
where
$a = 2 - \sqrt 3$
. The general problem of improving the convergence speed of the arctan series by transformation of the argument has also been considered in [6, 7]. In the present work the author considers an alternative form for the denominators in integrals. As a result, new series are obtained for multiples of π by some algebraic numbers.
ON THE DIFFERENCE OF COEFFICIENTS OF OZAKI CLOSE-TO-CONVEX FUNCTIONS
Authors: SIM YOUNG JAE , THOMAS DEREK K.
Published: June 2020

Let $f$ be analytic in the unit disk $\mathbb{D}=\{z\in \mathbb{C}:|z|<1\}$ and ${\mathcal{S}}$ be the subclass of normalised univalent functions given by $f(z)=z+\sum _{n=2}^{\infty }a_{n}z^{n}$ for $z\in \mathbb{D}$. We give sharp upper and lower bounds for $|a_{3}|-|a_{2}|$ and other related functionals for the subclass ${\mathcal{F}}_{O}(\unicode[STIX]{x1D706})$ of Ozaki close-to-convex functions.
Too Late to Apologize? Collateral Damage, Post-Harm Compensation, and Insurgent Violence in Iraq
Authors: Silverman Daniel
Published: June 2020

A key piece of conventional wisdom among scholars of modern armed conflict is that collateral damage is often strategically costly in war. Yet most combatants already know this and take actions after mistakes—most prominently, the distribution of “condolence payments” to civilian victims—in order to mitigate these costs. Do these payments work? This question is important not only for policymakers but also for deeper theoretical debates about how civilians respond to combatant signals in war. To examine these issues, I use micro-level conflict event data on 4,046 condolence payments made by Coalition forces to civilian victims during the Iraq War from 2004 to 2008, matching it with corresponding data on collateral damage and insurgent violence. The results of this analysis reveal that post-harm compensation does significantly diminish local rates of insurgent violence, and that this is true across different types of payments (cash handouts or in-kind assistance). Ultimately, these patterns can be best explained by a rationalist mechanism in which civilians update their beliefs about violent events based on new information about combatants’ wartime intentions. The results thus provide a compelling strategic rationale for combatants to compensate their victims in war, and suggest that civilians are not blinded to new information about conflict dynamics by their preexisting biases.
Extended role of transnasal oesophagoscopy: a review of the literature
Authors: Johnstone L , Tassone P , Burrows S , Nassif R , Vijendren A
Published: June 2020

Background

Advances in endoscopic technology have allowed transnasal oesophagoscopy to be used for a variety of diagnostic and therapeutic procedures.

Method

A review of the literature was carried out to look into the extended role of transnasal oesophagoscopy within otolaryngology, using the Embase, Cinahl and Medline databases.

Results

There were 16 studies showing that transnasal oesophagoscopy is safe and cost effective and can be used for removal of foreign bodies, tracheoesophageal puncture, laser laryngeal surgery and balloon dilatation.

Conclusion

This study presents a summary of the literature showing that transnasal oesophagoscopy can be used as a safe and cost-effective alternative or adjunct to traditional rigid endoscopes for therapeutic procedures.
Coronavirus disease 2019 communication: novel sign language system to aid surgical tracheostomy whilst wearing a respirator
Authors: Wilkinson S , Irvine E , Valsamakis T
Published: June 2020

Background

The coronavirus disease 2019 pandemic has necessitated rapid adaptations to all levels of clinical practice. Recently produced guidelines have suggested additional considerations for tracheostomy and advocated full personal protective equipment, including filtering facepiece code 3 masks. Air seal with filtering facepiece code 3 masks is often challenging, and full-face respirators and powered air-purifying respirators with hoods need to be employed. The infection prevention benefits of this equipment are accompanied by potential issues in communication.

Objective

In an attempt to minimise surgical error through miscommunication, the authors sought to introduce a simple sign language system that could be used as an adjunct during surgery.

Results

Following evaluation of pre-existing sign language platforms and consideration of multiple surgical factors, 14 bespoke hand signals were ultimately proposed.

Conclusion

Whilst this novel sign language system aims to bridge the communicative gap created by additional personal protective equipment, further development and validation of the proposed tool might be beneficial.
Cross-infectivity of honey and bumble bee-associated parasites across three bee families
Authors: Ngor Lyna , Palmer-Young Evan C. , Burciaga Nevarez Rodrigo , Russell Kaleigh A. , Leger Laura , Giacomini Sara June , Pinilla-Gallego Mario S. , Irwin Rebecca E. , McFrederick Quinn S.
Published: June 2020

Recent declines of wild pollinators and infections in honey, bumble and other bee species have raised concerns about pathogen spillover from managed honey and bumble bees to other pollinators. Parasites of honey and bumble bees include trypanosomatids and microsporidia that often exhibit low host specificity, suggesting potential for spillover to co-occurring beesviashared floral resources. However, experimental tests of trypanosomatid and microsporidial cross-infectivity outside of managed honey and bumble bees are scarce. To characterize potential cross-infectivity of honey and bumble bee-associated parasites, we inoculated three trypanosomatids and one microsporidian into five potential hosts – including four managed species – from the apid, halictid and megachilid bee families. We found evidence of cross-infection by the trypanosomatidsCrithidia bombiandC. mellificae, with evidence for replication in 3/5 and 3/4 host species, respectively. These include the first reports of experimentalC. bombiinfection inMegachile rotundataandOsmia lignaria, andC. mellificaeinfection inO. lignariaandHalictus ligatus. Although inability to control amounts inoculated inO. lignariaandH. ligatushindered estimates of parasite replication, our findings suggest a broad host range in these trypanosomatids, and underscore the need to quantify disease-mediated threats of managed social bees to sympatric pollinators.
The political use of victimhood: Spanish collective memory of ETA through the war on terror paradigm
Authors: Heath-Kelly Charlotte , Fernández de Mosteyrín Laura
Published: June 2020

Victims have become a topic of scholarly debate in conflict studies, especially regarding the impact of their activism on the evolution and termination of violence. Victims of terrorism are now enlisted within counter-terrorism, given their moral authority as spokespeople for counter-narratives and de-escalation. Our research explores how Spanish terrorism victims’ associations have evolved across eras of political violence and how they mediate the translation of international War on Terror discourses into Spanish counter-terrorism. We offer a topography of how the War on Terror has opened a ‘social front’ in Spanish counter-terrorism, with Spanish political elites prominently employing the victims’ associations to this end. Contemporary terrorism discourses are read back onto the memory of ETA, with victims’ associations assisting the equation of ETA with al-Qaeda and ISIS. Collective memory of the defeat of ETA has also contributed the veneer of ‘lessons learned’ to contemporary counter-terrorism measures. Our research explores the fluidity of terrorism-memory and the importation of global terrorism discourses into Spanish politics, relying upon interviews with key stakeholders in victims’ associations, local politics, and the research director of the new Victims of Terrorism Memorial Centre in Vitoria.
Inhibitory Control and Preschoolers’ Use of Irregular Past Tense Verbs
Authors: YUILE Amanda Rose , SABBAGH Mark A
Published: June 2020

We investigated whether children's inhibitory control (IC) is associated with their ability to produce irregular past tense verb forms as well as learn from corrective feedback following overregularization errors. Forty-eight 3;6 to 4;5 year old children were tested on the irregular past tense and provided with adult corrective input via models of correct use or recasts of errors following ungrammatical responses. IC was assessed with a three-item battery of tasks that required suppressing a prepotent response in favor of a non-canonical one. Results showed that IC was associated with children's initial production of irregular forms, but not associated with their post-feedback production. Findings are discussed in terms of current theories of past tense use and acquisition.
Between Emotion, Politics and Law: Narrative Transformation and Authoritarian Deliberation in a Land Dispute-triggered Social Drama in China
Authors: Liang Limin
Published: June 2020

Through studying a revenge murder triggered by a land dispute in China and the subsequent trial, this article explores “narrative transformation” in a social drama and proposes an event-based model for authoritarian deliberation. It argues that an obscure murder rose to prominence because it came to be narrated as a different kind of story. Initially viewed as “a normal killing,” it was transformed to represent a “contest” between a law-and-order frame, which emphasizes individual guilt, and a righteous-revenge frame, which symbolizes wider conflicts. The article also contends that in the absence of an institutionalized issue forum, contentious events present a model for authoritarian deliberation. That is to say, deliberation is often pegged to social dramas on the “judicial periphery,” thanks to a liminal phase inviting reflexivity, and exposes elite dissent that is otherwise veiled by an interest-driven alliance. In this case study, the media engaged with other institutions in contentious performances that affirmed hidden social fault-lines but also encouraged deliberation.
Ultrastructure of Fetal Mouse Heart in Organ Culture: Effects of Anoxia
Authors: Sybers H.D. , Ingwall J. , DeLuca M. , Ross J.
Published: June 2020

Fetal mouse hearts (FMH) can be maintained in organ culture for several weeks, and may offer a suitable model for studying cardiac metabolism under experimental conditions. Ultrastructural studies were performed to establish the integrity of the cells which have been deprived of circulating blood and to examine the effects of anoxia. Mouse hearts from fetuses (18-20 day gestation) were maintained for 2 days in oxygenated culture media 199 containing insulin 50 ug/ml.
Aging as a Compounding Variable in the Study of CNS Plasticity
Authors: Johnson J. E. , Yoesle R. A. , Mehler W. R.
Published: June 2020

In chronic experiments using animals, the time gap between the experimental manipulation and gathering the data (sacrificing the animal) may be quite large. In studies of plasticity in the central nervous system, utilizing as a model the lateral vestibular nucleus in the rat, we have found that there are a number of unusual ultrastructural changes that appear to occur at different ages. Data will be presented to show certain features of these normally occurring age changes that might easily be misinterpreted as experimental results.
Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation
Authors: Zucker W. H. , Mason R. G.
Published: June 2020

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.

In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.
Surface Features of the Collagen Fibril by Replica
Authors: Chatterjee T. K. , Spadaro J. A. , Vook R. W.
Published: June 2020

Current models for the packing of tropocollagen molecules to form the collagen fibril include spaces or ‘holes’ in the structure. It is the superposition of these holes and overlap regions that is thought to give rise to the distinctive banding in micrographs of stained and unstained collagen fibrils. The purpose of the present work was to determine whether or not this banding phenomenon is in fact reflected in the surface topography of fibril. The fibril surface does not seem to have been adequately studied, especially by replica techniques. We have found that replicas of fresh and vacuum-dried collagen indeed show periodic surface features apparently related to the banding detected by TEM.
Origin of the Inner Intine in Pollen of Canna
Authors: Rowley John R. , Skvarla John J.
Published: June 2020

Observations of development in the nonaperaturate pollen of Canna generalis Bailey, based upon light and electron microscopy, indicate that the inner intine of this species is initiated by plasmalemmasomes originating at widely separated areas of the cell surface.

The intine is that part of the pollen wall located between the sporopollenin exine and the cytoplasmic surface. It is often interbedded with the exine but is not itself composed of sporopollenin. In appearance and composition, the intine is comparable with the primary plant cell wall and has been characterized by Roland as an amorphous matrix of pectins with infrequent microfibrils.
Electron-Beam-Induced Phase Transition in Microcrystals of a Sphingosine Fat
Authors: Dorset D. L. , Turner J. N. , Parsons D. F.
Published: June 2020

The success of transmission electron diffraction analysis of organic crystal structures depends on two factors: (1) the amenability of the intensity data to treatment by the kinematical diffraction theory and (2) the minimization of radiation damage to the crystals themselves. Given the usual small range of atomic numbers in organic crystal components, condition (1), involving a description of the elastic scattering of the crystal, is often approximately satisfied for thin crystals. Condition (2), requiring a description of inelastic interactions between the electron beam and the organic crystal, has been a subject of great interest, particularly with a consideration of the possibility of high resolution imaging of unstained biological materials.
A Simple and Rapid Method of Adding Color to Photographic Projection Materials
Authors: Horner Jack A. , Pennington Catherine
Published: June 2020

It is becoming quite popular to utilize some colored materials with projection slides which would otherwise be black and white. For example, one might wish to show a black table or graph on a blue rather than a white background. Such presentations are aesthetically pleasing, reduce eye strain and glare, and add clarity to a presentation. There are several methods commonly used to achieve the colored effect. Perhaps the most obvious method would be to prepare the material on colored paper and photograph it with color film. This method is expensive, time consuming and precludes the use of already prepared black and white slides on file. Another method often used is to sandwich a colored theatrical gel between the cover glass. This generally results in wrinkling of the gel and makes the use of multiple colors difficult. Still another method utilizes photo water colors intended for print tinting but suffer from severe fading in a relatively short time.
X-Ray Energy Dispersive Analysis of Polyphosphate Bodies in Plectonema boryanum
Authors: Sicko-Goad Linda , Jensen Thomas E.
Published: June 2020

Polyphosphate bodies are one of several types of storage inclusions which are commonly found in microorganisms. They may be induced by various metabolic conditions, the most common of which are nutrient imbalance and disturbance of nucleic acid metabolism. Polyphosphate bodies are found in large numbers in cells that have been subjected to conditions of low available phosphate and then reinoculated into a medium containing phosphate. This phenomenon has been referred to by a variety of terms such as “rapid uptake”, the polyphosphate “overplus” phenomenon, and luxury storage. The polyphosphate bodies are osmotically inert long chain inorganic polymers. The exact chemical composition has, as yet, been difficult to ascertain. Chain length of the phosphate polymer can be analyzed by chromatography. However, only a few reports of polyphosphate bodies in protozoa have indicated that calcium and magnesium are constituents of the salt.
Mycoplasma-Like Bodies in Stunted Sorghum
Authors: Bradfute O. E. , Robertson Diane C.
Published: June 2020

Mycoplasma-like bodies (MB), as detected by electron microscopy, have been associated with many plant diseases, previously thought to be caused by viruses. The pathogen causing the Rio Grande strain of corn stunt (CS) is persistently transmitted to corn (Zea mays L.) and teosinte (Euchlaena mexicana Schrad.) by leafhopper species and has been associated with a spiral shaped MB termed spiroplasma. The presence of MB in stunted sorghum (Sorghum bicolor (L.) Moench) has not previously been reported.
Lipid Droplet Topolysis, Disruption and Resolution in Human Hepatocytes
Authors: Hruban Z. , Glagov S. , Chou S.F.
Published: June 2020

Accumulation of loose filamentous network at the periphery of lipid droplets and changes in adjacent cytomembranes were seen in hepatocytes of rats fed W-1372, a hypocholesterolemic agent (1). These alterations, termed topolysis, may represent a form of erosion and resolution of lipid droplets. They are similar to formations seen in lipid containing cells of normal animals such as the supracaudal gland of the guinea pig and the uropygial gland of the hen.

Similar changes were sought in hepatocytes of ten patients with fatty liver. Portions of needle biopsy specimens were fixed in cold 3% glutaraldehyde and postfixed in 1% osmium tetroxide. While usual lipid droplets are homogeneous, many of droplets in the studied patients were heterogeneous. They contained patches of very low electron density, electron lucent clefts, membraneous material, electron dense granules of various sizes and amorphous clumps.
Conformation of Ribosomes from Escherichia Coli
Authors: Boublik M. , Hellmann W. , Jenkins F.
Published: June 2020

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.
The Ultrastructural Cytochemistry of Oxidases and Dehydrogenases in Cochlear Hair Cell Mitochondria of the Guinea Pig
Authors: Spector G.J. , Carr C. , Arenberg I.K.
Published: June 2020

Enzyme systems from three major classes of oxido-reduction respiratory chain enzymes are studied by the use of osmiophilic cytochemical reagents. These are the pyridine-linked dehydrogenases - LDH (Fig. 1), the flavin-linked dehydrogenases- SDH (Fig. 2) and NADH2-D (Fig. 3), and the cytochromes - cytochrome c (Fig. 4).

Intravital and perilymphatic perfusions of the guinea pig cochlea were performed with phosphate buffered (pH 7.2 - pH 7.4) sucrose (0.2M) solutions containing specific substrates and osmiophilic reagents. Distyryl ditetrazolium salt (DS-NBT) was used in the dehydrogenase experiments.1 In the cytochrome studies, 3.3' diaminobenzidine (DAB) was employed. Following incubation and washing, the entire cochleae were osmicated in 1% unbuffered 0s04. The cochleae were embedded in araldite, dissected, sectioned in a LKB ultratome, viewed, and photographed in an RCA-EMU-3F electron microscope.
Acetylcholinesterase Localization with 3-Acetoxy-5-Indoledia-Zonium Chloride in Rat Spinal Cord Motor Neuron
Authors: Shannon W. Allen , Seligman Arnold M.
Published: June 2020

A number of methods based on different principles have been used in demonstrating acetylcholinesterase (AChE) activity in the central nervous system at the light and electron microscopic levels. In most of these, very specific controls and stringent comparisons must be made especially where other carboxylic acid esterases may be present.

The use of the substrate, 3-acetoxy-5-indolediazonium chloride (AID) (Fig. 1) gives a highly reliable method for cholinesterase due to the strong positive charge on the substrate and some specif icity for acetylcholinesterase due to the acetoxy moiety. The substrate can be used for light microscopy since it yields a reddish purple polymeric azo dye or black deposit on subsequent exposure to osmium tetroxide. For electron microscopy various osmication procedures are recommended, i.e., 2% osmium 60 min at room temperature, 2% osmium 60 min at 50°C or osmium vapor (0.5g/0.5ml distilled water) at 50°C for 30 or 60 min.
Unstained Biological Specimens in High Resolution Electron Microscopy
Authors: Lamvik M. K. , Pullman J. M. , Crewe A. V.
Published: June 2020

Negative staining and high resolution shadowing have been extensively used for structural studies in electron microscopy. However, these techniques cover the specimen with a layer of heavy salt or metal, and hence do not allow determination of true mass distribution or localization of specific sites using heavy atom markers. A prerequisite for such structural studies is an examination of unstained specimens. For thin specimens dark field microscopy must be used to obtain adequate contrast. The scanning transmission electron microscope is preferred for such studies since elastic, energyloss, and unscattered electrons can be recorded and analyzed quantitatively to form images with a minimum of beam-induced damage.
Stereological Determination of Nuclear Pore Density from Thin Sections of Nuclear Membrane
Authors: Loud Alen V.
Published: June 2020

The number of nuclear pores per square micron of nuclear envelope, NA, has been measured in tangential sections, freeze-etched preparations and isolated fragments of membrane. Estimates of NA for normal rat liver parenchymal cells have varied with the methodology used and range from 14 in freeze-etched nuclei in situ to 36 in negatively stained membranes. An entirely new and independent method for masuring NA, based on the principles of stereology, is presented here.
The Ultrastructure of the Nuclear Events of Binary Fission in Paramecium bursaria and the Effects of Colchicine on Cell Division
Authors: Lewis L. M.
Published: June 2020

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.

During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.
Distribution of Cilia in the Rat Nephron Studied by Scanning Electron Microscopy
Authors: Mumaw V. R. , Munger B. L.
Published: June 2020

The use of the scanning electron microscope (SEM) has become a very useful tool complimenting studies done by transmission electron microscopy (TEM). The presence of cilia in the renal epithelium have been noted by various investigators and described by Latta. The present study utilizing the SEM and a freeze fracture technique demonstrates the regularity of cilia as well as the surface topography of the renal epithelium in a fractured profile.
Ultrastructural Cytochemistry of Some Oxidative Enzymes
Authors: Seligman Arnold M.
Published: June 2020

The membrane-bound enzymes of the succinic oxidase chain of electron transport on the cristae of mitochondria have been the target of ultrastructural cytochemical research for a number of years. Methods for succinic dehydrogenase have been improved by the continuous design and synthesis of better tetrazolium salts. The most recent is BSPT, which is not osmiophilic, but yields an osmiophilic, lipophobic, insoluble formazan. The terminal triplet of the chain of electron transport or cytochrome oxidase, consisting of cytochrome c, a and a3 has been demonstrated very well via cytochrome c with diaminobenzidine (DAB). The localization of these two reaction products specifically on the outer surface of the inner mitochondrial membrane, lends some support to speculation concerning the mechanism of transfer of oxidative energy for ATP synthesis.
Recent Trends and Advances in Catalytic Osmiophilic Polymer Generation by Transition Metal Compounds in Ultrastructural Cytochemistry
Authors: Hanker J. S. , Thornburg L. P. , Romanovicz D. K.
Published: June 2020

The principle introduced in 1972, whereby the special ability of certain transition metal ions and compounds to catalyze the oxidative polymerization of aromatic amines such as Karnovsky's 3,3'-diaminobenzidine (DAB) was elucidated, has already been utilized in the electron microscopic demonstration of a number of enzymes. Thus small amounts of a transition metal compound selectively localized at the subcellular sites of a particular biomacromolecule or enzyme, are amplified by the generation of an osmiophilic indamine-type polymer at the sites. The electron-opaque osmium black end products resulting upon osmication remain unaltered during dehydration and embedment in plastic. Moreover, they are readily visible on 1-2 ¼m sections cut with a glass knife and thus guide and facilitate ultrathin sectioning.
Ribosome Structural Organization
Authors: Lake James A.
Published: June 2020

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.
Correlation Methods in Electron Image Analysis
Authors: Frank Joachim
Published: June 2020

Correlation methods play an important role in the analysis of electron micrographs. Through the development of the Fast Fourier transform algorithms, the computation of correlation matrices of large pictures has become a matter of seconds. In the following, a number of applications of digital analysis using the auto-correlation function (ACF) and the crosscorrelation function (CCF) are outlined.
Depth Distribution of Void Swelling Produced by 5 MeV Nickel Ions
Authors: Johnston W. G. , Rosolowski J. H. , Turkalo A. M. , Lauritzen T.
Published: June 2020

Our studies of void swelling produced by 5 MeV nickel ion bombardment rely on a theoretically calculated damage curve (Fig. 1). TEM measurements of void swelling are made in thin foils located in the peak damage region (~9000A from the original surface) according to the damage curve. Step-height measurements of swelling1 give the total swelling integrated along the entire ion path and we infer the dose dependence of swelling by assuming the distribution of swelling according to the calculated damage curve. With both measuring techniques the resulting information gives the dependence of swelling (ΔV/Vo) on the displacements per atom (dpa).
Effect of Shock-Pulse Duration on the Microstructure of Explosively Loaded Uniloy 326
Authors: Murr L.E. , Staudhammer K.P.
Published: June 2020

While there have been numerous experiments concerned with the effect of shock pressure on the residual structure of explosively loaded steels, there have been only two systematic attempts to investigate the effect of shock-pulse duration on the hardening of steels. And, in spite of the large number of shock loading studies concerned with the effect of pressure on the residual structure of many othre meals and alloys, there has been only one very limited attempt to investigate the effect of shock-pulse duration in explosively loaded copper.
Simplified Calculation of Phase Contrast for Finite Detector and Illumination Angles
Authors: Zeitler E. , Isaacson M.
Published: June 2020

Modern microscopes are capable of resolutions of the order of 2 Å. To fully utilize this capability, the experimentalist must turn to reliable calculations of contrast to optimize the various parameters available.

However, until recently (e.g. Ref. 1), most calculations of phase contrast were performed using restricted conditions such as parallel illumination in the CTEM and a point detector in the STEM, because exact calculations using general geometries became rather involved. This can be seen from Eq. (1) for phase contrast in the general case of finite illumination angle, αO, as a function of distance from and finite detector angle βO.
Studies of a Model DNA Sequence by Dark Field Electron Microscopy
Authors: Whiting R.F. , Ottensmeyer F.P.
Published: June 2020

Single heavy atoms in a variety of small model molecules have been managed by dark field transmission electron microscopy. The image intenses and geometry have been shown to be consistent with theoretical expectations. The use of this system for sequencing requires a demonstration theory accurate sequence can be derived for a small well-defined nucleic species. We have prepared and stained a homogeneous fragment of bacteria DNA. The molecule was a large pyrimidine oligomer anc b 5en sequenced biochemically. The sequence is shown in Fig. 1(a). Thymidine residues were marked with Beer's OsO4-cyanide stain. The refined, purified product was applied to pre-treated thin carbon specimen forms for electron microscopy.
Application of 100 kV Field Emission Electron Microscope
Authors: Harada Y. , Goto T. , Someya T.
Published: June 2020

It is noteworthy that high brightness of the field emission electron source increases the coherence length of the electron beam, making phase contrast more pronauced in high resolution electron microscopy. Some results related to this matter have been reported by the present authors, showing greatly improved phase contrast of lattice images obtained by a 100kV field emission microscope. This paper is an extension of our study on the coherence of field emission electron beams. Presented here are the results on quantitative determination of coherence length and the more advanced results on beam coherency.
High Resolution Observations of Topographical Contrast Using Transmission Electron Microscopy
Authors: Cullis A. G. , Maher D. M.
Published: June 2020

The study of specimen surface topography in transmission electron images requires, for example, the observation of thickness fringe displacements across crystalline samples or, in high resolution, the careful analysis of background phase contrast patterns. Alternatively, a surface may be replicated by shadowing using, for example, Pt/C and although this technique is capable of yielding extremely high topographical resolution, it is difficult to execute and often the original specimen is degraded during removal of the replica. In the present paper we describe the application of a technique which utilizes transmission microscopy and facilitates the study of fine surface features at high resolution. The technique involves the use of tilted illumination such that the main beam is partially obstructed by an axial objective aperture.
An Acquisition and Display System for Slow Scan Data
Authors: Woodruff David , Wiggins J. W. , Zubin J. A.
Published: June 2020

The Johns Hopkins University High Resolution Scanning Transmission Electron Microscope is serviced by a real-time dedicated digital data acquisition and display system. This system, whose block diagram is shown, is capable of accepting three eight-bit data samples from each scanning element of the microscope sweep. A major component of the system is a Digital Equipment Corp. PDP-11/20 processor and peripherals. The relevant peripherals, communicating with the machine's 12 K word, 900 nS core memory, are a disk storage unit of 1.2 M word capacity and two direct memory access interface units. Also participating, but not shown, are a hardware arithmetic unit and a magnetic tape unit. All of these are standard D. E. C. items. The storing scan converter, by Princeton Electronic Products, Inc., and its monitor are also purchased items.
A New 1000°C Double Tilt Stage for the Hitachi 650 kV Microscope
Authors: Worthington W. , Kosel T. , Sinclair R.
Published: June 2020

A new 1000°C specimen holder has been developed for the Hu-650 electron microscope and is interchangeable with other holders for the recently designed orthagonal drive tilting stage. The requirements for the high temperature device were as follows: 1. An orthogonal double-tilt stage with all original design criteria maintained(1). 2. Capability of heating standard (3mm. dia.) metallurgical specimens to 1000°C. 3. Geometry and materials should be such that stage and microscope components shall not be damaged by heat from the specimen holder. 4. The electric current to the heating element shall impart a minimum effect upon the microscope electron beam. 5. Heating and cooling rates to be as rapid as possible.
Montmorillonite Dendrites
Authors: Necip Güven  , Pease Rodney W.
Published: June 2020

Morphological features of montmorillonite aggregates in a large number of samples suggest that they may be formed by a dendritic crystal growth mechanism (i.e., tree-like growth by branching of a growth front).
Study of Au Precipitation from Solid Solution in Si
Authors: Cullis A. G.
Published: June 2020

In a previous study of impurity gettering in Si it was found that Au-containing precipitates were formed at the surfaces of wafers which had been equilibrated with Au at 1200°C and then subjected to B diffusion at 1000°C. The work reported in summary here relates to the characterization of the precipitates and to the construction of a model for their growth. This investigation involved the use of both the transmission electron microscope (TEM) and the scanning electron microscope (SEM). Full details will be reported elsewhere.
Electron Microscopy of Shock Loaded Polycrystalline Beryllium
Authors: Galbraith J. M. , Murr L. E. , Stevens A. L.
Published: June 2020

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.

This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.
An Electron Microscope Study of the Tishomingo Meteorite
Authors: Ives L. K. , Ruff A. W. , Reed R. P.
Published: June 2020

Tishomingo has an extremely coarse martensitic structure that is unique among meteorites. With a composition of 32.5 w/o Ni, 1.13 w/o Co, and 66.4 w/o Fe, its nickel concentration is among the highest found in meteorites. In a previous metallographic study, it was reported that approximately 79% of an original fcc ϒ-phase had apparently transformed to bcc α'-martensite with a macroscopic morphology that resembled man-made Fe-Ni alloys of similar composition that had been cooled to below the martensitic transformation temperature. This structure has not been observed in other meteorites although some approximation can be found in the high nickel plessite regions of more dilute nickel-iron meteorites exhibiting the commonly observed Widmanstatten structure. The main objective of this investigation was to examine the microstructure, determine the various phases and defect structures present and, in this way, obtain information on the sequence of thermal and mechanical events to which the meteorite had been exposed.
Technique for Using Internal SAED Standard on Particulate Samples
Authors: Grieger Gene R. , Teetsov Anna
Published: June 2020

For satisfactory identification of electron diffraction patterns it is necessary to know precisely the instrument constant. This constant is a complex function of lens current and sample position when using selected area electron diffraction. In previous work we have described how accuracy and reproducibility may be improved by the use of a digital voltmeter to monitor lens current. In the present paper we describe a technique designed to calibrate the instrument constant at the same specimen position and same lens current as the unknown sample which is being examined. One of the most commonly used techniques to accomplish this is the incorporation of a standard in the sample. In general this has been achieved by evaporating a standard on the sample so that the diffraction lines of the standard appear on the same photographic plate as the diffraction image of the unknown.
Enhancement of Contrast in the CEM and STEM Using Bumpy Specimens and Employing the “Dappled Field” Mode of Operation
Authors: Gandolfi L. , Reiffel J.
Published: June 2020

Calculations have been performed on the contrast obtainable, using the Scanning Transmission Electron Microscope, in the observation of thick specimens. Recent research indicates a revival of an earlier interest in the observation of thin specimens with the view of comparing the attainable contrast using both types of specimens.

Potential for biological applications of scanning transmission electron microscopy has led to a proliferation of the literature concerning specimen preparation methods and the controversy over “to stain or not to stain” in combination with the use of the dark field operating mode and the same choice of technique using bright field mode of operation has not yet been resolved.
Dynamic Scanning Electron Microscopy of Compressed Sand Grains Showing Strain Related Charging Patterns
Authors: Nixon W.C.
Published: June 2020

A special form of two lens scanning electron microscope has been optimised for scanning at television rates and used with a video tape recorder to observe a wide variety of dynamic specimen changes. The electron gun uses either thermionic tungsten or lanthanum hexaboride emitters giving low noise TV images with a beam current of 100 nA in an electron probe that can be as small as 300 A. Special stages may be used for dynamic microcircuit voltage contrast, mechanical motion such as ball bearing rotation, material testing in tension, compression and shear, and certain biological specimens such as human skin viewed directly in situ.
An Electron Microscopic Study of Kidney Cells in the Lizard Treated with Mercuric Chloride
Authors: Ooi E. C. V. , Chew E. C.
Published: June 2020

The nephrotoxicity of mercury is well established, especially in mammals and some fishes. However, no information on tissue alterations caused by mercurial compounds in reptiles is available. The present work was to study by using electron microscopy the cellular effects of mercury on kidney cells in the lizard, Gekko gekko. Twelve lizards were given single intraperitoneal injections of 12 mg/kg of mercuric chloride in saline. They were sacrificed after various intervals from 2 to 13 days. Four control animals received only saline injections.