bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the electron redistribution on the nonlinear saturation of Alfvén eigenmodes and the excitation of zonal flows
Authors: Biancalani A. , Bottino A. , Lauber P. , Mishchenko A. , Vannini F. 
Published: June 2020

Numerical simulations of Alfvén modes driven by energetic particles are performed with the gyrokinetic (GK) global particle-in-cell code ORB5. A reversed shear equilibrium magnetic field is adopted. A simplified configuration with circular flux surfaces and large aspect ratio is considered. The nonlinear saturation of beta-induced Alfvén eigenmodes (BAE) is investigated. The roles of the wave–particle nonlinearity of the different species, i.e. thermal ions, electrons and energetic ions are described, in particular for their role in the saturation of the BAE and the generation of zonal flows. The nonlinear redistribution of the electron population is found to be important in increasing the BAE saturation level and the zonal flow amplitude.
Scale-free architectures support representational diversity
Authors: Fields Chris , Glazebrook James F. 
Published: June 2020

Abstract
Gilead et al. propose an ontology of abstract representations based on folk-psychological conceptions of cognitive architecture. There is, however, no evidence that the experience of cognition reveals the architecture of cognition. Scale-free architectural models propose that cognition has the same computational architecture from sub-cellular to whole-organism scales. This scale-free architecture supports representations with diverse functions and levels of abstraction.
Successful simulation requires bridging levels of abstraction
Authors: Zhao Zidong , Mildner Judith N. , Tamir Diana I. 
Published: June 2020

Abstract
Although many simulations draw upon only one level of abstraction, the process for generating rich simulations requires a dynamic interplay between abstract and concrete knowledge. A complete model of simulation must account for a mind and brain that can bridge the perceptual with the conceptual, the episodic with the semantic, and the concrete with the abstract.
Simulation across representation: The interplay of schemas and simulation-based inference on different levels of abstraction
Authors: Schilling Malte , Chang Nancy , Rohlfing Katharina J. , Spranger Michael 
Published: June 2020

Abstract
Language comprehension of action verbs recruits embodied representations in the brain that are assumed to invoke a mental simulation (e.g., “grasping a peanut”). This extends to abstract concepts, as well (“grasping an idea”). We, therefore, argue that mental simulation works across levels of abstractness and involves higher-level schematic structures that subsume a generic structure of actions and events.
Is it always so? Unexpected visions
Authors: Deręgowski Jan B. , Tatler Benjamin W. 
Published: June 2020

Abstract
If we consider perceptions as arising from predictive processes, we must consider the manner in which the underlying expectations are formed and how they are applied to the sensory data. We provide examples of cases where expectations give rise to unexpected and unlikely perceptions of the world. These examples may help define bounds for the notion that perceptual hypotheses are direct derivatives of experience and are used to furnish sensible interpretations of sensory data.
Applications of Lattice Fringe Imaging
Authors: Sinclair R. 
Published: June 2020

The observation of closely-spaced lattice fringes is the common test for
assessing the resolution of a transmission electron microscope. The
capability regularly achieved by new instruments is 2.0 Å, although much
finer spaclngs are often attained without inordinate difficulty. This opens
up the possibility of examining materials at atomic plane level. In the
present article the areas of application of this technique are
outlined.
Lattice fringe imaging has evolved in a cautious manner. The main
difficulty is associated with how to relate the fringes to the positions of
the diffracting atomic planes in the specimen. As pointed out by Hirsch et
al. (1965) a simple correlation is generally not possible. In addition the
spacing and direction of the fringes may deviate from the crystal lattice
spacing and orientation when images are taken away from the exact Bragg
condition (Hirsch et al., 1965). For a dislocated crystal the situation may
be worse, with asymmetric fringe distortions on either side of a terminating
fringe, or multiple terminating fringes representing a single dislocation
(Cockayne, Parsons and Hoelke, 1971).
Introduction to Cell Membranes at Molecular Resolution
Authors: Barrnett R.J. 
Published: June 2020

This subject, is like observing the panorama of a mountain range,
magnificent towering peaks, but it doesn't take much duration of observation
to recognize that they are still in the process of formation. The mountains
consist of approaches, materials and methods and the rocky substance of
information has accumulated to such a degree that I find myself
concentrating on the foothills in the foreground in order to keep up with
the advance; the edifices behind form a wonderous, substantive background.
It's a short history for such an accumulation and much of it has been moved
by the members of the societies that make up this International
Federation.
My panel of speakers are here to provide what we hope is an interesting
scientific fare, based on the fact that there is a continuum of biological
organization from biochemical molecules through macromolecular assemblies
and cellular membranes to the cell itself. Indeed, this fact explains the
whole range of towering peaks that have emerged progressively during the
past 25 years.
Observation of Biological Specimens Using Dark Field STEM
Authors: Kokubo Y. , Inoue M. , Hosoi J. , Johansen B. V. 
Published: June 2020

Unstained biological specimens were observed in the dark field STEM mode
using a JEM-100CX TEMSCAN equipped with an annular type dark field detector.
It was confirmed, by comparing the micrographs obtained in the above mode
with micrographs obtained in the dark field CTEM mode, that the former were
superior in regard to observable detail.
In electron microscopy, it is a well known fact that the observation of
unstained biological specimens consisting of light elements such as carbon,
nitrogen, oxygen, etc., is extremely difficult due to the small scattering
factor involved. In general, although negative or positive staining by heavy
metallic elements is feasible for such specimens, the possibility of
structural, morphological and chemistry related (e.g., bonding) degradation,
as a result of such staining, is always present. Accordingly, freeze etching
and freeze sectioning, in spite of the complicated preparation procedure
involved, are becoming quite popular in that a specimen so treated, becomes
highly resistant to degradation resultant upon staining. A further popular
means for surmounting the above problems relating to specimen degradation,
poor contrast, etc. is the so-called “dark field method”, the salient
feature of which is that it is simple to utilize and dispenses with the
problems involved in the freeze etching and freeze sectioning techniques.
The main reason why dark field STEM is more effective than dark field CTEM
is that, in the case of former, there are no lenses below the specimen, thus
permitting thicker specimens to be observed without having to take into
consideration lens chromatic aberration caused by inelastic scattering.
Another reason Is that increased space availability allows a large angle
acceptance detector to be used, thereby enhancing the collection
efficiency1) of the elastically scattered electrons
which in turn ensures a high contrast image and low-dose specimen
observation.
Methods for Displaying Defocus and Astigmatism of High Resolution Stem
Images
Authors: Krakow William 
Published: June 2020

Focussing and stigmation of the objective lens for high resolution STEM
imaging is usually achieved by repeated reduced area scans of a given
specimen area under manual control of the instrument. This method is
particularly laborious since the scan times for images can be upwards of
several seconds which subjects a specimen to unwanted electron beam
exposure.
Methods have been proposed to optimize STEM images such as the use of
shadow images1 where a fixed beam pattern for a highly
defocussed objective lens is observed. This method again requires a high
beam dose in a given specimen area. Alternately, if a white noise object
such as a carbon film is used, granular image features without any
directionality are desired. In this case the eye must integrate over a large
number of small image features. A better alternative is the use computer
control to digitize images in real time and compute the power spectrum of an
image could be employed. This would require a dedicated high speed computer
system for a 1000 × 1000 display, but this latter method would have the
advantage that only a single scan of image is required.
Advantages of a Field Emission Gun for a Combined Analytical and High
Resolution Transmission Electron Microscope
Authors: Bentley J. 
Published: June 2020

This paper describes the various areas of analytical and high resolution
microscopy which can be greatly improved by the use of a high-brightness
field emission gun (FEG). The instrument used was a Philips EM400T equipped
with a FEG, 6585 STEM unit, EDAX EDS detector and Kevex 5100 spectrometer.
The <111> oriented W tip was supplied by the manufacturer.
The brightness β (current density per unit solid angle) normalized to
the ac-celeratiang voltage, V0 is defined by β =
4I/πd2α2jV0,
where I is the current in a probe of diameter d and divergence
αi. Results are presented in Table 1 for three
typical operating conditions. Probe currents >10−7 A
have been obtained in the TEM mode which is sufficient for work at medium
magnifications (20 to 100 K). Probe currents were measured from the screen
current/exposure time system which had been calibrated with a purpose built
Faraday cup. Probe diameters in TEM were measured from high magnification
TEM images and in STEM by imaging the STEM raster in the TEM mode. This is
possible because of the symmetric objective lens which can operate at the
same excitation in TEM and STEM. An example is shown in Fig. 1. The values
in Table 1 should be compared to conventional W hairpin sources for which β
≅ 1.
Plasmon Scattering Intensity in Small Aluminum Spheres
Authors: Batson P. E. 
Published: June 2020

It has generally been assumed that a relative thickness determination in
thin samples can be made by observing the variation of the bulk plasmon
scattering intensity. This method, of course, relies on the assumption that
the plasmon scattering varies with the
thickness,1
Here Ip is the plasmon intensity,
I0 is the incident beam intensity, λ is the total
scattering mean free path, t is the sample thickness, and ɛ is the bulk
dielectric constant for the material being probed. It can be
shown1 that the unscattered beam intensity is just
, and therefore a simple
ratio of the plasmon intensity to the unscattered beam intensity would seem
to give t, provided ʵ is known. It has been shown by
Ritchie2, however, that for thin films two more
terms occur in addition to that shown in (1). He found for the scattered
intensity,
where f and g arc some functions periodic in the thickness t. The third
term here is the normal surface plasmon scattering. The second is a surface
interference term at the bulk plasmon energy and is a manifestation of a
spatial quantization of the bulk plasmon in the direction perpendicular to
the film surfaces. (2) can be evaluated at the plasmon frequency
ωp,
A Preliminary Examination of Material Segregation in a Nuclear Waste
Glass
Authors: Howitt D. G. , DeNatale J. F. , McElfresh D. K. , Geiss R.H. 
Published: June 2020

The glasses proposed for nuclear waste containment are ideally
homogeneous in their dissolution of the waste components and relatively free
from devitrified products. Incomplete dissolution will likely result in poor
durability arising from the enhanced leachinq of the undissolved waste
materials whilst devitrified products might give rise to interfacial
decohesion and the provision of additional pathways for this same
effect.
A borosilicate glass similar in composition to those put forward as
candidates for commercial nuclear waste containment was combined with a
compatible mixture of simulated waste oxides at 1100°C for five hours. The
resulting glass was annealed for eighteen hours at the maximum
crystallization temperature of the pure glass and then quenched to room
temperature prior to examination by electron microscopy.
Ferroelectric Domain Structure of
Pb(Zr.52Ti.48)03
Authors: Goo E.K. , Mishra R.K. 
Published: June 2020

Ferroelectric domains are twins that are formed when PZT undergoes a
phase transformation from a non-ferroelectric cubic phase to a ferroelectric
tetragonal phase upon cooling below ∼375°C.,1 The
tetragonal phase is spontaneously polarized in the direction of c-axis,
making each twin a ferroelectric domain.
Thin foils of polycrystalline Pb
(Zr.52Ti.48)03
were made by ion milling and observed in the Philips EM301 with a double
tilt stage.
Observations of Gas Bubbles in an Austenitic Stainless Steel Charged
with3H
Authors: Sklad P. S. 
Published: June 2020

Nitronic 40 is a high-strength austenitic stainless steel.
Investigations are in progress to explore the possibility of using this
material as a high-strength substitute for 300 series stainless steels,
especially in hydrogen environments. There is also interest in determining
the influence of helium on the mechanical properties of this material from
the viewpoint of fusion reactor systems. The alloy is nominally (in weight
percent) 21 Cr, 6 Ni, 9 Mn, and 63 Fe and is strengthened by 0.35 wt %
N.
Smooth bar tensile specimens approximately 3.5 mm in diameter with 25 mm
gage lengths were machined from high energy rate forged (HERF) stock. These
specimens were then gas phase charged with 2H at 64 MPa
pressure at 470 K or 3H at 47.5 MPa at 345 K for 1450
h. Due to the nature of the charging the 3H
distribution was nonuniform, ranging from approximately 1300 ppm at the
specimen surface to less than 5 ppm at a depth of 0.5 mm from the surface.
Following charging, the specimens were stored at ˜250 K for 5.5 years.
Approximately one-third of the tritium decayed to 3He
during this period, yielding a maximum of 900 ppm of
3He at the surface of the specimens. Tensile tests at
298 K revealed a significantly greater loss in ductility in the specimens
charged with 3H. Following tensile testing TEM
specimens of suitable size were sectioned near the fracture surface, thinned
using conventional techniques for radioactive specimens, and examined.
Electron microscopy was performed in a Philips EM 400T equipped with a field
emission gun.
Preparation of Thin Graphite Supporting Films
Authors: Crewe A. V. , Mittleman R. K. , Rosman R. L. 
Published: June 2020

One of the principal limitations of high resolution microscopy is the
nature of the substrates which are used. In particular it is important that
the substrate upon which the specimen sits not limit the resolution of the
microscope.
There are two requirements which the substrate must fulfill. First of
all it must be free of diffusible hydrocarbons and heavy atom contaminants.
Secondly it must be flat and uniform over a large area. These criteria are
met by thin crystals such qs graphite. Such crystals will, unlike amorphous
substrates, produce uniform background signals which can be sub-stracted
from the overall signal.
Early Foreign Body Reaction in the Mouse Lung to Intravenously Injected
Polymer Beads
Authors: Coleman S. E. , Hood C. I. , Schoen F. J. , Robinson M. 
Published: June 2020

The local interaction between biomaterials and host tissue is important
in a number of problems involving surgically implanted medical devices. The
foreign body reaction (FBR) is typically studied by surgical implantation,
but it is difficult to distinguish the differences between surgical trauma
and FBR, especially after short implantation times. In particular, surgical
implantation models preclude mechanistic inferences as well as qualitative
and quantitative assessment of fine differences in biocompatibility among
materials.
To develop a non-surgical model for FBR, divinyl benzene copolymer beads
(Biobeads SX-8, BioRad) were injected into the tail vein of mice, embolizing
to the lung. We observed granuloma development over periods of 5 minutes to
1 year. Each animal was injected with 10,000 Biobeads (average diameter,
0.005 cm). After intervals of 5 minutes; 3, 6, 12, 24 and 48 hours; 4 and 8
days; 6 and 16 weeks; and 1 year, the animals were sacrificed, the lungs
perfused per trachea with glutaraldehyde-paraformaldehyde fixative and
prepared for light and electron microscopy.
Can Myocardial Cellular Hyperplasia be Produced in Hearts of Adult Dogs
By Electronic Pacing?
Authors: Adomian G. E. , Osborne S. , Laks M. 
Published: June 2020

As demonstrated in the pulmonary arterial banded heart, myocardial cell
size increases concomitantly with ventricular weight. However, in some dogs
cell size did not parallel the increase in weight. This disparity may have
been due to edema and/or fibrosis. Although not considered to occur in the
adult heart, myocardial cell hyperplasia may be the important cause of the
disparity. Therefore the aim of this study was to test the hypothesis that
myocardial cell size may not always increase concomitantly with ventricular
weight.
Arterioventricular block was produced in 14 adult mongrel dogs by the
Beazell technique in which a transvenous electrode catheter is utilized to
electrocoagulate the AV node without thoracotomy (1,2).Apical right
ventricular pacing catheters were used to electronically pace the heart at
70 bpm for 4-60 months. From the paced and normal groups, matched samples
were obtained from the left ventricular base and processed in Epon 812 for
microscopy. Cell length and width were measured on 1100 cells.
Ultrastructural Studies on an Unidentified Microorganism in Urine
Authors: Sun C. N. , Morgan P. N. , Herring F. , White H. J. 
Published: June 2020

We recently studied the fine structure of unusual microorganisms in a
urine specimen. To our knowledge, previous electron microscopic
investigation of these microorganisms has never been done.
The microorganisms were found in the sediments of two separate urine
specimens obtained from a 55 year old patient. In these samples, there were
yeast cells and two types of gram negative microorganisms; a typical
rodlike, non-mobile bacterium, and a spheroid form with two projections. The
latter organisms were varying sizes and moved by a typical serpent-like
motility. The rod-like structures were approximately 0.4 - 1 μ in diameter
and up to 8 μ in length. The spheroid structures, which stained
homogeneously and were not spore-like in appearance, were approximately 6 μ
in diameter. A few intermediate or transitional forms of various sizes and
shapes were also found.
An Ultrastructural Analysis of the Lipid Bodies of Trigonella Foe
Num-Graecum
Authors: Gacek Walter F. 
Published: June 2020

Ultrastructural cyfochemical studies were conducted on dry seed
cotyledons of fenugreek (Trigonella foenum - graecum)to determine the
composition of the lipid storage bodies. These seeds are used as an
industrial source of steriods which are extracted with hexane. These lipids
have been analysed to be in the glycoside form (1). Lipid solvent extraction
methods were coupled to periodate oxidation methods (2) at the
ultrasctructuraI level to determine the position of components having both
lipid and saccharide characteristics.
Normally dry cotyledon storage cells fixed by conventional electron
microscopic methods show numerous large protein bodies that occupy most of
the cellular volume. Surrounding these bodies, there are numerous tightly
packed lipid bodies (Fig. 1). Plastids with plastoglobuli may also be found
in the surrounding cytoplasm (Fig. 3). Dry cotyledons which are stored in
diethyl ether at room temperature for 2 weeks and subsequently processed for
electron microscopy show a loss of the lipid bodies which surround the
protein bodies (Fig. 2). Acetone and hexane were not as efficient in lipid
removal.
Electron Microscopic Analysis of active and Repressed Chromatin within
Normal and Neoplastic Human Cells
Authors: Frenster J. H. 
Published: June 2020

Chromatin within the nuclei of animal cells consists of DNA molecules in
non-covalent association with such intra-nuclear macromolecules as histones,
acidic proteins, lipoproteins, and RNA species (1). These associated ligands
and counter-ligands direct the molecular conformation and biological
activity of DNA molecules within intact cell nuclei and within the intact
chromatin complexes that can be isolated from such cell nuclei (2).
Two major phase states of chromatin are recognized by ultrastructural,
bio-synthetic, and biophysical criteria, and these two states of chromatin
contain DNA template molecules that are either active in or repressed for
RNA synthesis (3). DNA template molecules active in RNA synthesis are found
within extended euchromatin microfibrils (Chart 1) which contain increased
amounts and kinds of acidic proteins, lipoproteins, and RNA species. Each of
these molecular species Is capable of activating for RNA synthesis the DNA
molecules within repressed heterochromatin (Chart 1). By contrast, the DNA
molecules within condensed heterochromatin are found to be repressed for RNA
synthesis (3), and such repressed heterochromatin is relatively devoid of
acidic proteins, lipoproteins, and RNA species.
Characterization of a Motile Cellular Domain Arising During the
Amoebo-Flagellate Transformation of Physarum Polycephalum
Authors: Pagh K.I. , Adelman M.R. 
Published: June 2020

Unicellular amoebae of the slime mold Physarum polycephalum undergo
marked changes in cell shape and motility during their conversion into
flagellate swimming cells (l). To understand the processes underlying motile
activities expressed during the amoebo-flagellate transformation, we have
undertaken detailed investigations of the organization, formation and
functions of subcellular structures or domains of the cell which are
hypothesized to play a role in movement.
One focus of our studies is on a structure, termed the “ridge” which
appears as a flattened extension of the periphery along the length of
transforming cells (Fig. 1). Observations of live cells using Nomarski
optics reveal two types of movement in this region:propagation of
undulations along the length of the ridge and formation and retraction of
filopodial projections from its edge. The differing activities appear to be
associated with two characteristic morphologies, illustrated in Fig.
1.
Intracellular Accumulation of Uranium and Lead in Collembolan
(Insect)
Authors: Humbert W. 
Published: June 2020

The midgut epithelium of Collembola contains cytoplasmic inclusions
known to be important intracellular sites of mineral sequestration (1). The
present study is focused on the role played by these inclusions in cases of
heavy metal poisoning. Ultrastructural and X-ray microanalytical studies
allowed us to find out different possible mechanisms involved in storage and
excretion of these metals.
Experiments have been made by rearing the Insects on diet impregnated
with the heavy metal (1 % aqueous solutions of uranyl acetate and lead
citrate). For each series 100 animals were tested. Animals alive after 2
months were fixed for electron microscopy with glutaraldehyde and osmium
tetroxyde. Semi-thin sections were analysed with an electron microprobe
analyser CAMECA MS 46 equipped with wavelength dispersive spectrometers
(W.D.S.) at 15 KV ; beam current was 40 nA. X-ray microanalysis of thin
unstained sections was performed on a “CAMEBAX” microanalyser equipped for
transmission with W.D.S. at 50 KV and with a beam current of 100 nA. The use
of R.E.T. crystal to detect uranium and lead avoids any misinterpretation
(2).