bluuebunny/crossref_metadata_2025 huggingface dataset:
IRRIGATION, SPACING AND CULTIVAR EFFECTS ON NET PHOTOSYNTHETIC RATE, DRY MATTER PARTITIONING AND PRODUCTIVITY OF RICE UNDER SYSTEM OF RICE INTENSIFICATION IN MOLLISOLS OF NORTHERN INDIA
Authors: DASS ANCHAL , CHANDRA SUBHASH
Published: April 2013

Field experiments were conducted on a Typic Hapludoll (Mollisols) soil in the Indo-Gangetic Plains of India during the 2008 and 2009 rainy seasons to (1) find out the effect of irrigation schedules and plant spacing on physiological parameters, yield and water productivity of two rice cultivars under System of Rice Intensification (SRI), and (2) compare the performance of SRI with conventional transplanting (CT). Treatments under SRI included 12 combinations of three irrigation schedules,viz.irrigation at 1, 3 and 5 day(s) after disappearance of ponded water (DADPW), two spacing intervals (20 × 20 cm and 25 × 25 cm) and two cultivars (‘Pant Dhan 4’ and ‘Hybrid 6444’). The two control treatments were the CT of each cultivar. The experiment was set in a factorial randomized complete block design replicated thrice. The net photosynthetic rate (NPR) of the topmost fully expanded leaf at tillering and that of flag-leaf at flowering stage was affected significantly by irrigation schedules. Irrigating rice crop at 1 or 3 DADPW, being at par with each other, recorded significantly higher NPR than 5 DADPW. The increase in NPR at 1 and 3 DADPW was 17.1% and 8.4% at tillering and 13.6% and 6.1% at flowering stage, respectively, compared with that at 5 DADPW (tillering: 12.78 μmol CO2m−2S−1, flowering: 16.01 μmol CO2m‑2S−1). At closer spacing (20 × 20 cm) the cultivars did not differ significantly for NPR; however, at wider spacing (25 × 25 cm), ‘Hybrid 6444’ showed significantly higher NPR than ‘Pant Dhan 4’. Between two methods, SRI recoded higher NPR. Dry matter accumulation (DMA) in leaves and grains declined with delay in irrigation from 1 to 5 DADPW. Wider spacing significantly enhanced DMA in stems and grains. ‘Hybrid 6444’ showed higher DMA in all plant parts than ‘Pant Dhan 4’. Grain yield was not affected significantly by irrigation schedules in 2008, while in 2009, irrigation at 1 and 3 DADPW resulted in 12.8% and 8.0% higher grain yield, respectively, than 5 DADPW (5.84 t ha−1). Wider spacing was superior to closer spacing. SRI improved grain yield by 16.9% and water productivity by 18.5% over CT.
Intra-operative application of confocal endomicroscopy using a rigid endoscope
Authors: Just T , Pau H W
Published: April 2013

Objective:

To introduce the application of confocal endomicroscopy during microlaryngoscopy, to enable intra-operative evaluation of human laryngeal epithelium.

Methods:

A rigid endoscope was connected to the scanner head of a Heidelberg Retina Tomograph II confocal laser scanning system via an adapter. The endoscope was gently placed on the surface of a vocal fold through a laryngoscope during microlaryngoscopy.

Results:

The application of confocal endomicroscopy using a rigid endoscope enabled technical improvements (i.e. improved image quality, automatic volume scan, and reduced tissue pressure due to the presence of a perforation plate with central hole at the end of the endoscope) which permitted greater sensitivity and improved handling. Confocal endomicroscopy provided good quality,in vivo, en-face images and enabled an assessment of laryngeal epithelium volume.

Conclusion:

This method enables the surgeon to monitor epithelial changes in pre-malignant lesions. The combination of confocal endomicroscopy together with optical coherence tomography (as a complementary technique that provides optical cross-sections) should be further explored in a formal clinicopathological study.
Altered top-down and bottom-up processing of fear conditioning in panic disorder with agoraphobia
Authors: Lueken U. , Straube B. , Reinhardt I. , Maslowski N. I. , Wittchen H.-U. , Ströhle A. , Wittmann A. , Pfleiderer B. , Konrad C. , Ewert A. , Uhlmann C. , Arolt V. , Jansen A. , Kircher T.
Published: April 2013

Background

Although several neurophysiological models have been proposed for panic disorder with agoraphobia (PD/AG), there is limited evidence from functional magnetic resonance imaging (fMRI) studies on key neural networks in PD/AG. Fear conditioning has been proposed to represent a central pathway for the development and maintenance of this disorder; however, its neural substrates remain elusive. The present study aimed to investigate the neural correlates of fear conditioning in PD/AG patients.

Method

The blood oxygen level-dependent (BOLD) response was measured using fMRI during a fear conditioning task. Indicators of differential conditioning, simple conditioning and safety signal processing were investigated in 60 PD/AG patients and 60 matched healthy controls.

Results

Differential conditioning was associated with enhanced activation of the bilateral dorsal inferior frontal gyrus (IFG) whereas simple conditioning and safety signal processing were related to increased midbrain activation in PD/AG patients versus controls. Anxiety sensitivity was associated positively with the magnitude of midbrain activation.

Conclusions

The results suggest changes in top-down and bottom-up processes during fear conditioning in PD/AG that can be interpreted within a neural framework of defensive reactions mediating threat through distal (forebrain) versus proximal (midbrain) brain structures. Evidence is accumulating that this network plays a key role in the aetiopathogenesis of panic disorder.
Environmental influences on familial resemblance for drug abuse in first-cousin pairs: a Swedish national study
Authors: Kendler K. S. , Ohlsson H. , Sundquist K. , Sundquist J.
Published: April 2013

Background

Using three independent methods, prior studies in Swedish sibling pairs indicate that environmental factors contribute substantially to familial aggregation for drug abuse (DA). Could we replicate these results in cousin pairs?

Method

Using multiple Swedish public databases (1964–2011), we defined DA using medical, legal or pharmacy registry records and examined concordance in full cousin pairs as a function of age differences, younger–older relationships and geographical proximity while growing up.

Results

Replicating prior results in siblings, cousin pairs were significantly more similar in their history of DA if they were (i) closer versus more distant in age and (ii) grew up in high versus low geographical proximity to one another. Furthermore, controlling for background factors, having an older cousin with DA conveys a greater risk for DA than having a younger drug-abusing cousin. The greater transmission of DA from older to younger versus younger to older cousin was more prominent in pairs who grew up close to one another. In age difference and geographical proximity analyses, effects were consistently strongest in male–male cousin pairs. In analyses of older → younger versus younger → older transmission, effects were stronger in male–male and male–female than in female–female or female–male relative pairs.

Conclusions

In accord with prior results in siblings, environmental factors contribute substantially to the familial aggregation of DA in cousins and these effects are, in general, stronger in males than in females.
Cyclic pursuit in a multi-agent robotic system with double-integrator dynamics under linear interactions
Authors: Sharma Balaji R. , Ramakrishnan Subramanian , Kumar Manish
Published: April 2013

We investigate the controlled realization of a stable circular pursuit model in a multi-agent robotic system described by double-integrator dynamics with homogeneous controller gains. The dynamic convergence of the system starting from a randomly chosen, non-overlapping initial configuration to a sustained, stable pursuit configuration satisfying velocity matching and uniform inter-agent separation is demonstrated using the proposed control framework. The cyclic pursuit configuration emerges from local, linear, inter-agent interactions and is shown to be robust under stochastic perturbations of small and moderate intensities. The stability criterion discussed in this work is independent of the number of agents, permitting dynamic addition/deletion of agents without affecting overall system stability. Experimental results that validate the key theoretical results are also presented. Potential applications of the results obtained include cooperative perimeter tracking and resource distribution applications such as border patrol and wildfire monitoring.
A temporal analysis of wealth in eighteenth-century Ottoman Kastamonu
Authors: ERGENE BOĞAÇ A. , KAYGUN ATABEY , COŞGEL METIN M.
Published: April 2013

This article studies temporal variations in wealth levels and distribution in an Ottoman context during the eighteenth century. By analysing the probate estate inventories of the Muslim deceased in Kastamonu, located in north-central Anatolia, we demonstrate that real wealth levels generally declined over the course of the century. Our analysis also suggests that the economic conditions of poor men, if not women, deteriorated more so than those of the rich, fuelling growing inequality. The article explores the factors that contributed to these trends and discusses the relevance of our findings for long-term economic development patterns in the region from a comparative perspective.
Secularisation and the religious components of marriage seasonality in the Don Army Territory (Southern Russia), 1867–1916
Authors: BONNEUIL NOËL , FURSA ELENA
Published: April 2013

The quality of the statistical archives of the Don Army Territory for the period 1867–1916 offers a unique opportunity to compare the denominations present (Orthodox, Old Believers and Coreligionists, Catholics, Lutherans, Jews, Armenian-Gregorians, Lamaist Buddhists and Muslims) in a context of urbanisation, secularisation and industrialisation. The observance of religious interdicts varied between and within denominations depending on levels of urbanisation and the district considered. These contrasts reveal the segmentation of Don society, the constraints imposed by agrarian imperatives and military obligations, the differences in the economy and between town and country, and the advance of secularisation or persistence of tradition.
Parliamentary enclosure, vermin and the cultural life of English parishes, 1750–1850
Authors: CRAGOE MATTHEW , MCDONAGH BRIONY
Published: April 2013

This article explores the impact of parliamentary enclosure on the cultural life of English villages after 1750. It focuses on parish-sponsored vermin control, arguing that the popular ‘hunting’ sanctioned by parish vestries under Tudor legislation, and persisting into the early nineteenth century, created a highly participatory recreational culture which continued to exist under the radar of the game laws. Using a sample of parishes from the heavily enclosed county of Northamptonshire, the article demonstrates that this communal activity survived the reworking of the landscape by parliamentary enclosure, and that, by extension, the level of disruption to village cultural life was less than has been suggested.
The importance of ideology: the shift to factory production and its effect on women's employment opportunities in the English textile industries, 1760–1850
Authors: MINOLETTI PAUL
Published: April 2013

This article uses data from the 1833 Factory Inquiry to assess male and female occupations and earnings in factory textile production. These data are contrasted with evidence drawn from various sources on male and female employment in domestic industry. The period from 1760 to 1850 was a time of dramatic change in the nature and location of textile production, with important consequences for women's work. Whilst economic factors explain many of the changes we see, gender ideology had a powerful effect on how the labour market operated, and this was increasingly the case over this period as the organisation of work became more formalised and hierarchical.
Loss of melanoregulin (MREG) enhances cathepsin-D secretion by the retinal pigment epithelium
Authors: FROST LAURA S. , LOPES VANDA S. , STEFANO FRANK P. , BRAGIN ALVINA , WILLIAMS DAVID S. , MITCHELL CLAIRE H. , BOESZE-BATTAGLIA KATHLEEN
Published: April 2013

Cathepsin-D (Cat-D) is a major proteolytic enzyme in phagocytic cells. In the retinal pigment epithelium (RPE), it is responsible for the daily degradation of photoreceptor outer segments (POSs) to maintain retinal homeostasis. Melanoregulin (MREG)-mediated loss of phagocytic capacity has been linked to diminished intracellular Cat-D activity. Here, we demonstrate that loss of MREG enhances the secretion of intermediate Cat-D (48 kDa), resulting in a net enhancement of extracellular Cat-D activity. These results suggest that MREG is required to maintain Cat-D homeostasis in the RPE and likely plays a protective role in retinal health. In this regard, in theMregdsu/dsumouse, we observe increased basal laminin. Loss of theMregdsuallele is not lethal and therefore leads to slow age-dependent changes in the RPE. Thus, we propose that this model will allow us to study potential dysregulatory functions of Cat-D in retinal disease.
Vibrational Spectroscopic Microscopy: Raman, Near-Infrared
and Mid-Infrared Imaging Techniques
Authors: Lewis E. Neil , Levin Ira W.
Published: April 2013

New instrumental approaches for performing vibrational Raman,
near-infrared and mid-infrared spectroscopic imaging microscopy
are described. The instruments integrate imaging quality filters
such as acousto-optic tunable filters (AOTFs), with visible
charge-coupled device (CCD) and infrared focal-plane array
detectors. These systems are used in conjunction with
infinity-corrected, refractive microscopes for operation in
the visible and near-infrared spectral regions and with
Cassegrainian reflective optics for operation in the mid-infrared
spectral interval. Chemically specific images at moderate spectral
resolution (2 nm) and high spatial resolution (1 μm) can be
collected rapidly and noninvasively. Image data are presented
containing 128 × 128 pixels, although significantly larger
format images can be collected in approximately the same time.
The instruments can be readily configured for both absorption
and reflectance spectroscopies. We present Raman emission images
of polystyrene microspheres and a lipid/amino acid mixture
and near-infrared images of onion epidermis and a hydrated
phospholipid dispersion. Images generated from mid-infrared
spectral data are presented for a KBr disk containing
nonhomogeneous domains of lipid and for 50-μm slices of
monkey cerebellum. These are the first results illustrating
the use of infrared focal-plane array detectors as chemically
specific spectroscopic imaging devices and demonstrating their
application in biomolecular areas. Extensions and future
applications of the various vibrational spectroscopic imaging
techniques are discussed.
Structures of a Stacking Fault and a Rotational Domain Boundary
in CVD α-Silicon Nitride
Authors: Zhou D.S. , Mitchell T.E.
Published: April 2013

A 1/2[0001](0001) stacking fault and a planar
60° rotational domain boundary on the (0001) plane in as-grown
CVD α-Si3N4 crystals have been
characterized by high-resolution electron microscopy and image
simulation. As reported previously, two types of coherent
boundaries have been observed in this material, namely, stacking
faults and rotational domain boundaries. The former involves
only a translational displacement, while the latter separates
two grains by a 60° rotation in addition to a translation.
Inasmuch as the difference resulting from the rotational component
can hardly be detected by high-resolution electron microscopy,
care must be taken to analyze them first by analytical electron
microscopy. In this paper, these two types of boundaries are
studied and structural models are constructed that give simulated
images in satisfactory agreement with observed images.
Design and Initial Performance of an Ultrahigh Vacuum Sample
Preparation Evaluation Analysis and Reaction (SPEAR) System
Authors: Collazo-Davila C. , Landree E. , Grozea D. , Jayaram G. , Plass R. , Stair P.C. , Marks L.D.
Published: April 2013

Results concerning the calibration and use of a new ultrahigh
vacuum (UHV) surface preparation and analysis system are reported.
This Sample Preparation Evaluation Analysis and Reaction (SPEAR)
side chamber system replaces an older surface side chamber that
was attached to a Hitachi UHV H-9000 microscope. The system
combines the ability to prepare clean surfaces using sample
heating, cooling, ion milling, or thin film growth with surface
analytical tools such as Auger electron spectroscopy (AES),
X-ray photoelectron spectroscopy (XPS), and scanning electron
microscopy (SEM), along with atomic surface structure information
available from high-resolution transmission electron microscopy
(HREM). The chemical sensitivity of the XPS and AES are
demonstrated in preliminary studies of catalytic and semiconductor
samples. In addition, the surface preparation capabilities are
also demonstrated for the Si(100) and Ge(100) surfaces, including
the ability to acquire secondary electron images during milling.
During operation, the entire system is capable of maintaining
the UHV conditions necessary for surface studies.
An Improved Mean Atomic Number Background Correction for
Quantitative Microanalysis
Authors: Donovan John J. , Tingle Tracy N.
Published: April 2013

Quantitative EPMA (electron probe microanalysis) intensity
measurements require an accurate correction for the X-ray continuum
(or background) created by the Bremsstrahlung effect from the
primary electron beam. This X-ray continuum, as measured on
a wavelength-dispersive spectrometer at any particular wavelength,
is primarily a function of the mean atomic number of the material
being analyzed. One can calibrate the dependence of the continuum
on mean atomic number by measuring and curve fitting the X-ray
intensities at the analytical peak in pure elements, oxides,
and binary compound standards that do not contain any of the
analyte or any interfering elements and use that calibration
to calculate the X-ray background correction. For unknown samples,
the mean atomic number is determined from the elemental
concentrations calculated by the ZAF or φ(ρz) matrix
correction, and the fit regression coefficients are used
iteratively to calculate the actual background correction. Over
a large range of mean atomic number we find that the dependence
of the continuum intensity on mean atomic number is well described
by a second-order polynomial fit. In the case of low-energy
X-ray lines (<1 to 2 keV), this fit is significantly improved
by correcting the X-ray continuum intensities for absorption.
For major and most minor element analyses, the improved mean
atomic number background correction procedure presented in this
paper is accurate and robust for a wide variety of samples.
Empirical mean atomic number background data are presented for
a typical 10-element silicate and a 15-element sulfide analytical
set up that demonstrate the validity of the technique as well
as some potential limitations.
Dark-Field and Marginal Imaging with a Thin-Annular Detector
in STEM
Authors: Liu R.-J. , Cowley J.M.
Published: April 2013

The use of a thin annular detector in a scanning transmission
electron microscope is shown, theoretically and experimentally,
to allow several imaging modes that may be of value for the
study of thin specimens. The diffraction pattern on the detector
plane may be expanded or contracted by means of post-specimen
lenses to vary the collection angle of the thin annular detector
to form dark- or bright-field images. Dark-field images obtained
from annuli of various radii in the diffraction pattern can
selectively reveal different components of the sample, as
illustrated in the case of a sample containing platinum
crystallites, amorphous carbon, and carbon nanotubes. Amorphous
materials of different composition can be distinguished by
selecting the main maxima in their diffraction patterns. If
the central beam is enlarged so that it just fills the inner
aperture of the detector, the “marginal” imaging
mode so achieved gives an image contrast that is proportional
to the square of the differential of the projected potential
distribution. Any deflection of the incident beam spot due to
a change of the projected potential gives bright contrast in
the image.
Dark-Field X-Ray Microscopy of Immunogold-Labeled Cells
Authors: Chapman Henry N. , Fu Jenny , Jacobsen Chris , Williams Shawn
Published: April 2013

The methods of immunolabeling make visible the presence of
specific antigens, proteins, genetic sequences, or functions
of a cell. In this paper we present examples of imaging
immunolabels in a scanning transmission x-ray microscope using
the novel method of dark-field contrast. Colloidal gold, or
silver-enhanced colloidal gold, is used as a label, which strongly
scatters x-rays. This leads to a high-contrast dark-field image
of the label and reduced radiation dose to the specimen. The
x-ray images are compared with electron micrographs of the same
labeled, unsectioned, whole cell. It is verified that the
dark-field x-ray signal is primarily due to the label and the
bright-field x-ray signal, showing absorption due to carbon,
is largely unaffected by the label. The label can be well
visualized even when it is embedded in or laying behind dense
material, such as the cell nucleus. The resolution of the images
is measured to be 60 nm, without the need for computer processing.
This figure includes the x-ray microscope resolution and the
accuracy of the label positioning. The technique should be
particularly useful for the study of relatively thick (up to
10 μm), wet, or frozen hydrated specimens.
Microstructure of Polycrystalline MgO Penetrated by a Silicate
Liquid
Authors: Ramamurthy Sundar , Mallamaci Michael P. , Zimmerman Catherine M. , Carter C. Barry , Duncombe Peter R. , Shaw Thomas M.
Published: April 2013

Dense, polycrystalline MgO was infiltrated with monticellite
(CaMgSiO4) liquid to study the penetration of liquid
along the grain boundaries of MgO. Grain growth was found to
be restricted with increasing amounts of liquid. The inter-granular
regions were generally found to be comprised of a two-phase
mixture: crystalline monticellite and a glassy phase rich in
the impurities present in the starting MgO material. MgO grains
act as seeding agents for the crystallization of monticellite.
The location and composition of the glassy phase with respect
to the MgO grains emphasizes the role of intergranular liquid
during the devitrification process in “snowplowing”
impurities present in the matrix.
Secondary Ion Mass Spectrometry (SIMS) Microscopy as an Imaging
Tool for Physiological Studies II. SIMS Microscopy of Plant
Tissues
Authors: Grignon Nicole , Halpern Sylvain , Jeusset Josette , Fragu Philippe
Published: April 2013

Serious difficulties are encountered when SIMS analysis is
applied to plant cells because of the cells' basic
organization. In most plant cells, the cytoplasm is present
as a thin layer that surrounds a large central vacuole, and
is surrounded externally by a porous semi-rigid cell wall. Due
to the high internal hydrostatic pressure typical of plant cells,
large-scale solute redistribution may occur when tissues are
excised. Relatively small solute decompartmentation is sufficient
to collapse the native solute gradients between the cytoplasm
and the adjacent compartments, due to the small volume of the
former. For these reasons, most of the SIMS analyses in plant
cells have been performed on elements bound to non-diffusible
structures such as proteins, cell wall polymers, or in dry seeds.
Sample preparation remains a limiting factor when imaging the
distribution of soluble compounds. Cryotechniques have generated
considerable interest to circumvent these problems. Cryofixation
followed by cryosectioning would a priori be the best procedure,
but encouraging results indicate that cryofixation followed
by cryosubstitution is an interesting alternative.
A New Electron-Optical Mode for High Contrast Imaging and
Online Stereo Observation in TEM
Authors: Fan G.Y. , Young S.J. , Deerinck T. , Ellisman M.H.
Published: April 2013

We describe a new electron-optical configuration for transmission
electron microscopy (TEM). In this novel mode, the objective
mini-lens is strongly excited so that the back focal plane of
the objective lens is imaged onto the plane of the selected-area
aperture with a magnification of 3.2. Thus, the selected-area
aperture can function as an objective aperture either in place
of or in addition to the conventional objective aperture. This
new configuration, which has been implemented on a JEOL 4000EX
high voltage electron microscope, provides improved resolution
and contrast in images of thick biological specimens and also
facilitates the use of beam tilt for stereo image acquisition.
The Life and Achievements of Albert E. Prebus, Ph.D., D.Sc.,
Hon.
Authors: Watson John H.L.
Published: April 2013

One of the two men who first brought the electron microscope to the
North American continent in 1938 died on December 16, 1997, at his home in
Columbus, Ohio. This description of Dr. Albert Prebus' life is not so
much an obituary as it is a recognition of a quiet, modest, unassuming
scientist, whose pioneering work in electron microscopy contributed
directly to the great explosion of scientific knowledge, which has been
characteristic of the last half of the twentieth century.
Microscopy Society of America (MSA) Placement Office: Positions
Open
Authors: Watson John H.L.
Published: April 2013

This list contains brief descriptions of each of the positions known
to be open in Microscopy Society of America (MSA) Placement Office files
as of January 1, 1998. Potential employers are urged to use the Placement
Office as widely as possible to advertise their needs to MSA members.
Likewise, MSA members who are seeking employment in microscopy are urged
to register with the Office to receive data on open positions
periodically.
Net Notes
Authors: Whittaker Scott D.
Published: April 2013

Well it's time again for another edition of Net Notes. This
edition is for you biological science technicians out there. Maybe this
discussion can speed up cell and bacterial processing for SEM so you can
take longer lunches. This discussion is archived in full at the Tips &
Tricks site located at www.biotech.ufl.edu/~emcl. Good luck.
Exploring Spatial Resolution in Electron Back-Scattered Diffraction
Experiments via Monte Carlo Simulation
Authors: Ren S.X. , Kenik E.A. , Alexander K.B. , Goyal A.
Published: April 2013

A Monte Carlo model was used to simulate specimen-electron beam
interactions relevant to electron back-scattered diffraction (EBSD).
Electron trajectories were calculated for a variety of likely experimental
conditions to examine the interaction volume of the incident electrons as
well as that of the subset of incident electrons that emerge from the
specimen, i.e., back-scattered electrons (BSEs). The spatial resolution of
EBSD was investigated as functions of both materials properties, such as
atomic number, atomic weight, and density, and experimental parameters,
such as specimen thickness, tilt, and incident beam accelerating voltage.
These simulations reveal that the achievable spatial resolution in EBSD is
determined by these intrinsic and extrinsic parameters.
Lenses for Electron Microscopy and Microanalysis: Shadowgraph Method
of Determining Focal Properties and Aberration Coefficients
Authors: Rempfer Gertrude F. , Fyfield Margaret S. , Griffith O. Hayes
Published: April 2013

The performance characteristics of electron microscopes and
probe-forming instruments depend ultimately on the focal properties and
aberrations of electron lenses. A practical method of experimentally
determining the properties of electron lenses is described. The method
utilizes shadows cast by two meshes inserted separately in front of the
lens and behind the lens to study the properties of the image of a point
source. The image properties are then used to calculate the lens
properties. The paraxial values of the focal length and focal distance as
well as their spherical and chromatic aberrations are determined.
Experimental data and the analysis are presented in the form of a tutorial
that has been tested in the classroom. Discussions of the relationship
between image properties and lens properties, in particular, focal point
aberrations and focal length aberrations, and the various ways aberration
coefficients can be defined, are included to clarify concepts in optics
that are important for microscopists.
Microscopy of Spotted Fever Rickettsia Movement through Tick
Cells
Authors: Munderloh Ulrike G. , Hayes Stanley F. , Cummings Joel , Kurtti Timothy J.
Published: April 2013

Spotted fever group (SFG) rickettsiae are obligate intracellular
prokaryotes that include tick-borne pathogens of vertebrates as well as
nonpathogenic organisms living in symbiotic association with their tick
hosts. We investigated the ability of SFG rickettsiae to move between and
within host cells using tick cell culture and a SFG rickettsial isolate
from a lone star tick (Amblyomma americanum) collected in Missouri.
The isolate (MOAa), which is closely related to Rickettsia montana,
grew in cell lines from the ticks Ixodes scapularis and
Rhipicephalus appendiculatus. Transmission electron microscopy
demonstrated that immediately following entry into tick cells, rickettsiae
escaped from the host cell membrane, and intracellular rickettsiae came to
lie in direct contact with host-cell cytoplasm. There was evidence of damage
to the endoplasmic reticulum membrane which was broken down into vesicular
structures. When rickettsiae exited host cells, host membrane stretched
around them but was lost before re-entry. Use of a fluorescein-tagged
monoclonal antibody to rickettsial outer membrane protein B and
rhodamine-labeled phalloidin demonstrated association of actin tails with
rickettsiae and suggested that SFG rickettsiae utilized host cytoskeletal
components for movement. During early stages of infection, when cells
harbored only one or a few organisms, “comet tails” of F-actin
formed on one end of rickettsial cells, presumably pushing them ahead.
Actin tails were not seen during later stages of infection when tick cells
became completely filled with rickettsiae.
In Situ Electron Microscopy: Introduction
Authors: Crozier Peter A. , Sharma Renu
Published: April 2013

This issue of Microscopy and Microanalysis contains invited and
contributed papers from the 1998 Arizona State University (ASU) Workshop
on In Situ Electron Microscopy, held January 7-10 at the Embassy Suites in
Scottsdale, Arizona. This was the eighteenth in a series of Workshops
organized annually by the Facility for High Resolution Electron Microscopy
in the Center for Solid State Science at ASU. The Workshops are part of an
educational program, and are intended to foster interaction and
collaboration between researchers in electron microscopy. The workshop was
attended by over 80 participants from universities, industries, and
government laboratories around the world. Many of the contributions to the
workshop are included in this issue.
Time-Resolved High-Resolution Transmission Electron Microscopy Using
a Piezo-Driving Specimen Holder for Atomic-Scale Mechanical
Interaction
Authors: Kizuka Tokushi , Tanaka Nobuo , Deguchi Shunji , Naruse Mikio
Published: April 2013

Time-resolved high-resolution transmission electron microscopy at a
spatial resolution of 0.2 nm and a time resolution of 1/60 sec using a
piezo-driving specimen holder is reported here. Various types of atomic
processes in mechanical interaction, such as contact, bonding,
deformation, and fracture, in nanometer-sized gold crystallites and carbon
nanotubes are demonstrated.
In Situ High-Temperature Transmission Electron Microscopy
Observations of the Formation of Nanocrystalline TiC from Nanocrystalline
Anatase (TiO2)
Authors: Agrawal A. , Cizeron J. , Colvin V.L.
Published: April 2013

In this work, the high-temperature behavior of nanocrystalline
TiO2 is studied using in situ transmission electron microscopy
(TEM). These nanoparticles are made using wet chemical techniques that
generate the anatase phase of TiO2 with average grain sizes of
6 nm. X-ray diffraction studies of nanophase TiO2 indicate the
material undergoes a solid-solid phase transformation to the stable rutile
phase between 600° and 900°C. This phase transition is not
observed in the TEM samples, which remain anatase up to temperatures as
high as 1000°C. Above 1000°C, nanoparticles become mobile on the
amorphous carbon grid and by 1300°C, all anatase diffraction is lost
and larger (50 nm) single crystals of a new phase are present. This new
phase is identified as TiC both from high-resolution electron microscopy
after heat treatment and electron diffraction collected during in situ
heating experiments. Video images of the particle motion in situ show the
nanoparticles diffusing and interacting with the underlying grid material
as the reaction from TiO2 to TiC proceeds.
Oxidation and Reduction of Small Palladium Particles on Silica
Authors: Crozier Peter A. , Sharma Renu , Datye Abhaya K.
Published: April 2013

We have used the technique of in situ electron microscopy to study the
oxidation and reduction of the palladium (Pd) catalysts. In this study, we
have subjected a Pd catalyst to oxidation and reduction cycles and studied
the changes in particle structure and morphology with in situ electron
diffraction and imaging. The PdO particles can be reduced to Pd metal in
situ at temperatures as low as 200°C in an atmosphere of a few Torr of
both H2 and O2. We also found that essentially the
same reduction occurred in the vacuums of 10−6 to
10−7 Torr in two different electron microscopes. Our in
situ reduction studies show that many of the oxide particles form voids
when reduced to Pd metal. The decrease in volume that occurs during
reduction is often accommodated by a combination of particle shrinkage and
void formation. The production of voids does not seem to depend on either
the reducing atmosphere or the rate of reduction, although the voids
appear to be unstable above 500°C.
In Situ Observations of the Interaction of Liquid Lead Inclusions
with Grain Boundaries in Aluminum
Authors: Gabrisch Heike , Dahmen Ulrich , Johnson Erik
Published: April 2013

The evolution of liquid lead (Pb) inclusions at grain boundaries in
aluminum (Al) was investigated by direct in situ TEM observation in the
temperature range from 330°–643°C, In agreement with earlier
reports on quenched alloys, the characteristic contact angle of the
lens-shaped grain boundary inclusions was found to be near 120°. This
angle remained approximately constant over the entire temperature range,
ruling out the possibility of a wetting transition. Coarsening of grain
boundary inclusions was observed to proceed mainly by Ostwald ripening,
although coalescence could also be observed. Inclusions at grain
boundaries, at triple junctions, and at the intersection of grain
boundaries with the foil surfaces adopted characteristic shapes that were
shown to be equilibrium forms. At the highest temperatures, the grain
boundaries were observed to detach from the inclusions and the interaction
of a migrating grain boundary with inclusions could be observed.
In Situ Studies of the Interaction of Dislocations with Point
Defects during Annealing of Ion Implanted Si/SiGe/Si (001)
Heterostructures
Authors: Stach Eric A. , Hull Robert , Bean John C. , Jones Kevin S. , Nejim Ahmed
Published: April 2013

Strained layer heterostructures provide ideal systems with which to
study the dynamics of dislocation motion via in situ transmission electron
microscopy, as the geometry, strain state, and kinetics can be
characterized and directly controlled. We discuss how these structures are
used to study dislocation-point defect interactions, emphasizing the
experimental requirements necessary for quantification of dislocation
motion. Following ion implantation, different concentrations and types of
point defects are introduced within the SiGe epilayer depending on the
implantation species, energy, and current density. By annealing samples in
situ in the transmission electron microscope (TEM) following implantation,
we can directly observe dislocation motion and quantify the effect of
dislocation-point defect interactions on dislocation velocities. We find
that dislocation motion is impeded if the implantation dose peak lies
within the epilayer, as dislocations pin at point defect atmospheres.
Shallow BF2 implantation into the sample capping layer results
in more complicated behavior. For low current density implants,
dislocation velocities may be dramatically increased; at higher current
densities the magnitude of this increase is significantly smaller.
Implantation of different ions separately implicates fluorine as the
species responsible for the observed increases in dislocation velocities,
presumably due to an electrical effect on the rate of dislocation kink
nucleation.
In Situ Transmission Electron Microscopy Observations of
Silicidation Processes for Cobalt Thin Films Deposited on Silicon
Authors: Sidorov Maxim V. , Kardynal Beata , Smith David J.
Published: April 2013

Morphological evolution associated with silicidation of Co thin films
deposited on (100) and (111) Si substrates has been followed using
transmission electron microscopy with in situ thermal annealing from
ambient temperature up to 850°C. Noticeable structural changes
associated with the formation of CoSi2 occur at temperatures as
low as 400°C and the reaction is essentially complete at about
500°C. Prolonged heating above 500°C leads to CoSi2
grain growth and coalescence and, finally, to pinholes formation.
Silicidation of Co films on (100) and (111) Si substrates follows the same
pattern. The morphology of films annealed in situ is similar to those
annealed ex situ except that the Si/CoSi2 interface appears
to be much rougher. This behavior is associated with the specific geometry
of cross-sectional TEM specimens, where surface diffusion dominates bulk
diffusion. Very thin Co films, which have less contribution from surface
diffusion than thicker films, are ideal for studying dynamic phenomena at
Co/Si reactive interfaces.
Image Enhancement in a Reflection Optical Microscope by Suppression
of Diffusing Photons Using Polarizing Annular Objectives
Authors: Schilders S.P. , Gan X.S. , Gu Min
Published: April 2013

In this report, we describe the implementation of an angle-gating
mechanism into a reflection optical microscope for imaging through a
turbid medium. A significant improvement in image resolution and contrast
is obtained when a polarizing annular objective is used to image a
reflective test bar through various turbid media. The experimental results
confirm that the improvement is caused by the efficient suppression of
diffused photons scattered from the turbid medium when a polarized annular
objective is employed as an angular gate.
Atomic Structures of Oxygen-associated Defects in Sintered Aluminum Nitride Ceramics
Authors: Yan Yanfa , Pennycook S. J. , Terauchi M. , Tanaka M.
Published: April 2013

Convergent-beam electron diffraction and Z-contrast imaging are used to study oxygen-associated
defects, flat inversion domain boundaries, dislocations, and interfaces in sintered AlN ceramics. The structures
of these defects are directly derived from atomic-resolution Z-contrast images. The flat inversion domain
boundaries contain a single Al-O octahedral layer and have a stacking sequence of . . .bAaB-bAc-CaAc. . ,
where -cAb- indicates the single octahedral layer. The expansion at the flat inversion domain boundaries is
measured to be 0.06 (±0.02) nm. The interfaces between 2H- and polytypoid-AlN are found to be also inversion
domain boundaries but their stacking sequence differs from that of the flat inversion domain boundaries.
Method for Cross-sectional Transmission Electron Microscopy Specimen Preparation of Composite Materials Using a Dedicated Focused Ion Beam System
Authors: Yaguchi Toshie , Kamino Takeo , Ishitani Tohru , Urao Ryoichi
Published: April 2013

A new method for transmission electron microscope (TEM) specimen preparation using a focused
ion beam (FIB) system that results in a lower rate of gallium (Ga) implantation has been developed. The
method was applied to structural and analytical studies of composite materials such as silicon (Si)-devices and
magneto-optical disk. To protect the specimens against Ga ion irradiation, amorphous tungsten (W) was
deposited on the surface of the specimen prior to FIB milling. The deposition was quite effective in reducing
the Ga implantation rate, and energy-dispersive X-ray (EDX) analysis of these specimens detected 0.3Ð1.5% Ga
incorporated in the thinned area. FIB milling times for these specimens were 1.5Ð2 hr. Although the milling rate was high, all the materials were properly prepared for TEM study,
and clear crystal lattice images were observed on all specimens.
Low-magnification Quantitative X-ray Mapping of Grain-boundary Segregation in Aluminum–4 wt.% Copper by Analytical Electron Microscopy
Authors: Carpenter D.T. , Watanabe M. , Barmak K. , Williams D.B.
Published: April 2013

Abstract: Quantitative X-ray mapping in the analytical electron microscope (AEM) could improve the statistics of grain-boundary segregation measurements if high spatial resolution can be maintained at lower magnifications (<500 kX). Typically, only about 10 boundaries are analyzed because of the difficulty of conventional AEM measurements; however, a low-magnification quantitative X-ray map could contain twice this number of boundaries in a single field of view. Microscope conditions and mapping parameters have been explored for operation at ∼250 kX, under a variety of conditions to illustrate the trade-offs between various characteristics, such as analytical resolution, counting statistics, magnification, and acquisition time. From these data, it is possible to extrapolate to maps generated under different conditions and estimate their limitations with respect to these characteristics. A simple model has been developed to describe the behavior of inclined grain boundaries that can be used to estimate the detectability of segregant as a function of boundary tilt. Using quantitative X-ray maps, grain boundary Cu coverage has been measured from 55 boundaries in Al–4 wt.% Cu with minimal user effort. For fine-grained thin films, mapping is substantially more efficient than other methods of data acquisition and may be used to measure segregation at large numbers of boundaries.
Origin of Threefold Periodicity in High-Resolution Transmission Electron Microscopy Images of Thin Film Cubic SiC
Authors: Kaiser U. , Chuvilin A. , Brown P.D. , Richter W.
Published: April 2013

Abstract: High-resolution transmission electron microscopy (HRTEM) images of the [1–10] zone of cubic SiC layers grown by molecular beam epitaxy (MBE) often reveal regions of material exhibiting an unusual threefold periodicity. The same contrast was found in earlier works of Jepps and Page, who attributed this contrast in HRTEM images of polycrystalline SiC to the 9R-SiC polytype. In this report we demonstrate by HRTEM image simulations that the model of the 9R polytype and an alternative twinning model can fit qualitatively the experimental HRTEM images. However, by comparing the fast Fourier transform (FFT) patterns of the experiments and the simulations, as well as by using dark-field imaging, we show unambiguously that only the model of overlapping twinned 3C-SiC crystals fully agrees with the experiments.
Direct Evidence for Grain Boundary Potential Barrier Breakdown via In Situ Electron Holography
Authors: Johnson Kevin D. , Dravid Vinayak P.
Published: April 2013

Abstract: Static and dynamic grain boundary potential barrier effects are directly observed at high spatial resolution for a varistor of model structure and chemistry. Grain boundary mechanisms for nonlinear electrical behavior are investigated for Nb-doped SrTiO3 bicrystals by in situ high-resolution electron holography under applied current coupled with electrical measurements. For the static case, holography reveals a positive grain boundary barrier of about 0.45 V, which is indicative of positive grain boundary charge adjoined by negative space charge regions. Under high applied current, in situ holography records the breakdown of this grain boundary barrier in accord with the macroscopic varistor effect, which is reflected in bulk I-V experiments.
Transmission Electron Microscopy-A Textbook for Materials Science, by David B. Williams and C. Barry Carter
Authors: Brown Reviewed by Paul D.
Published: April 2013

When a new textbook on transmission electron microscopy is published and all of one's colleagues, established research scientists and graduate students alike, immediately go out and buy a copy–some even using their own money–then that is probably the best recommendation a book can ever get!
Variation in applicator positions during interfraction high-dose rate brachytherapy in carcinoma cervix: dosimetric evaluation
Authors: Passi Kamlesh , Aggarwal Lalit M. , Vashistha Rajesh , Singh Bikramjit , Kaur Parveen , Gupta Sureshchandra J. , Kehwar Than S.
Published: April 2013

Purpose

This study was designed to study the variations in different geometrical and dosimetric parameters.

Materials and methods

In this study, two groups comprises 21 and 28 patients, who were treated with 9·5 Gy × 2 Fx and 7·5 Gy × 3 Fx, respectively, using microselectron high-dose rate (HDR) remote control unit. All patients were analysed using orthogonal radiographs to evaluate variations in different parameters.

Results

Variations in different parameters are more in Group II patients than in Group I patients, which show that the variation in geometrical and dosimetrical parameters increases with increasing HDR number of fractions.

Conclusion

In the reporting of an outcome of multiple fractionation of HDR treatments resultant dosimetric parameters must be evaluated and must be used for clinical interpretation.
Secularism, Religion, and Political Choice in the United States
Authors: Beard T. Randolph , Ekelund Robert B. , Ford George S. , Gaskins Ben , Tollison Robert D.
Published: April 2013

The effect of religion on political behavior and attachment has been a topic of intense interest in the United States and elsewhere. Less attention has been paid to the issue of secularism. Some analysts have viewed secularism as anabsenceof religious attachment, and a number of studies have utilized indices of secularization to analyze such topics as economic development or modernization. In this article, we show that secularism, like religion, is in fact a multifaceted category, and should not be viewed as the antithesis of religiosity. Utilizing a very large sample of United States adults, we apply factor analysis to demonstrate that secularism is composed of two logically separate components, and we use these results to examine the role of secularism in political attachments. We suggest thatReligious SecularismandSocial Secularismare different motivations and have different effects on political behavior and that, politically, the marginal effects of Social Secularism are larger than Religious Secularism in all cases.
Human motion classification using a particle filter approach: multiple model particle filtering applied to the micro-Doppler spectrum
Authors: Groot Stephan , Harmanny Ronny , Driessen Hans , Yarovoy Alexander
Published: April 2013

In this article, a novel motion model-based particle filter implementation is proposed to classify human motion and to estimate key state variables, such as motion type, i.e. running or walking, and the subject's height. Micro-Doppler spectrum is used as the observable information. The system and measurement models of human movements are built using three parameters (relative torso velocity, height of the body, and gait phase). The algorithm developed has been verified on simulated and experimental data.